UPDATED JANUARY 2015
1. GENERAL INFORMATION
According to World Health Organization (WHO) classification, published in 2008, chronic lymphocytic leukaemia (CLL) is defined as a lymphoproliferative disorder, composed by monomorphic round B lymphocytes involving peripheral blood (PB), bone marrow (BM) and lymphoid organs (Swerdlow 2008). Chronic lymphocytic leukaemia lymphocytes are clonal CD19-positive B cells characterised by a peculiar immunophenotypic profile, coexpressing CD5 and CD23, along with low density of CD20 (CD20 dim). To fulfil the leukaemia diagnosis, the B-lymphocyte count should reach at least 5×109/L and the lymphocytosis should persist at a second evaluation performed after at least 3 months. The less frequent non-leukaemic cases, where lymph node involvement is prevalent, in absence of cytopoenias due to BM infiltration and with less than 5×109/LB lymphocytes in the PB, are classified as small-lymphocytic lymphomas (SLL) (Swerdlow 2008; Hallek 2008; Shanafelt 2010). This condition represents a different clinical manifestation of the same disease and follows the same management guidelines as CLL. Cases with less than 5×109/LB lymphocytes, with the typical CLL-like immunophenotypic profile and no other signs or symptoms of lymphoproliferative disorders, should be classified as CLL-like monoclonal B cell lymphocytosis (CLL-like MBL), a recently defined entity (see 3.4 «Monoclonal B cell lymphocytosis») (Shanafelt 2010).
1.2 Incidence and Prevalence
Chronic lymphocytic leukaemia represents the most common leukaemia among adults in Western Countries. Incidence rate is similar in Europe and US and ranges between 4 to 6 cases per 100,000 person per year. In US about 15,720 new cases of CLL, and more than 12,000 in EU, are expected in 2014. The incidence increases by age, with more than 70% of patients being older than 65 years at diagnosis. Though the median age at diagnosis is 72 years, in the last decades CLL is more often diagnosed also in younger individuals, with almost 15% of patients of 55 years old or younger. There is a gender predisposition, as men are more frequently affected by CLL than women (male:female ratio of 1.5-2:1) (Howlader 2013).
1.3 Risk factors
Several of the epidemiological studies aimed at identifying risk factors for CLL/SLL occurrence, but no acquired causative factors leading to CLL development have been identified so far. A genetic predisposition to disease development has been ascertained and it is supported by several lines of evidence. First of all, the strongest and most consistent risk factor for CLL/SLL occurrence is represented by a family history of haematological malignancies (CLL and/or non-Hodgkin lymphomas, NHL). Relatives of CLL patients have a 2-to-8-fold increase in the risk of developing CLL and a 2-fold increase of NHL, compared to the general population (Slager 2013; Slager 2014; Goldin 2009). Up to 10% of CLL cases reported two or more individuals affected by CLL in the same family, defining the condition of “familial” CLL, that share the same clinical and biological profile of sporadic cases. The disease is rarer in the Eastern world (China, Korea, and Japan) and this lower incidence is maintained in migrants and their progeny (Boggs 1987; Pan 2002). Finally, linkage studies and, more recently, genome wide association studies identified more than 20 susceptibility loci, where many candidate genes, involved in B-cell biology and apoptotic pathway, are located (Di Bernardo 2008; Crowther-Swanepoel 2010a; Berndt 2013; Crowther-Swanepoel 2010b).
Different studies suggested a link between CLL diagnosis and occupational and lifestyle factors, with people living or working on a farm being at higher risk of CLL development, while sun exposure having a protective role (Slager 2014). An association between hepatitis C (HCV) infection and CLL development has also been noted, though not being CLL-specific, as HCV infection is associated with a wide variety of lymphoproliferative disorders (Marcucci 2011).
It has been recently demonstrated that the management of CLL patients by disease-specific well trained haematologists results in longer time to first treatment and a significant improvement in progression-free and overall survival (Shanafelt 2012). Chronic lymphocytic leukaemia patients referred to qualified haematology/oncology centres are more likely to perform prognostic testing, to receive updated treatment and be enrolled in clinical trials. These issues are particularly relevant for high-risk patients (see 1.3 «Risk factors») whose adverse prognosis could be improved only through the access to novel experimental agents.
2. PATHOLOGY AND BIOLOGY
Peripheral blood smears in CLL cases show a high number of small lymphocytes with scanty cytoplasm and clumped chromatin. The presence of smudge cells or Gumprecht nuclear shadows (i.e., ruptured CLL cells) is a frequent finding, related to the characteristic fragility of the cell membrane, and was considered a hallmark of this disease (Matutes 2000). Prolymphocytes (larger cells with prominent central nucleolus) can be admixed to small lymphocytes in variable proportions, but usually represent less than 55% of the cells. An increased (between 10% and 55%) percentage of prolymphocytes is frequently associated with a more aggressive clinical course (Swerdlow 2008).
Chronic lymphocytic leukaemia diagnosis does not require lymph node biopsy nor bone marrow aspirate/biopsy, since a typical immunophenotype performed on the peripheral blood is sufficient for a conclusive diagnosis. If lymph node biopsy is performed for clinical reasons (SLL cases, differential diagnosis), nodal involvement by CLL/SLL shows a pseudofollicular pattern where regularly-spaced pale areas (called “proliferation centres”), composed by larger cells, are divided by a background of smaller and darker cells (Ponzoni 2011). Bone marrow infiltration may be interstitial, nodular and/or diffuse, and in most cases the lymphoid infiltrate represents >30% of the cellularity (Hallek 2008).
Peripheral blood immunophenotype is required to confirm CLL diagnosis in any case of unknown lymphocytosis. First of all, flow cytometry should be used to assess the clonality of B-cell expansion, showing the evidence of light chain restriction (i.e., either kappa or lambda typically at low levels of expression). Chronic lymphocytic leukaemia cells express B-cell markers, like CD19, along with low levels of CD20, and are positive for CD5 and CD23. The use of these markers is needed for the differential diagnosis with others B-cell lymphoproliferative disorders, in particular to exclude the diagnosis of mantle cell lymphoma, that is positive for CD5 but negative for CD23. Chronic lymphocytic leukaemia cells are usually negative for FMC7 and express low levels of surface immunoglobulins (in most cases IgM and/or IgD, rarely IgG or IgA) (Table 1).
Table 1. Immunophenotype in CLL and other lymphoproliferative disorders.
|CLL: chronic lymphocytic leukaemia; MCL: mantle cell lymphoma; SMZL: splenic marginal zone lymphoma; B-PLL: B-cell prolymphocytic leukaemia|
2.3 Genomic aberrations
At variance with other lymphoproliferative disorders (e.g., follicular lymphoma or mantle cell lymphoma), in most of which a distinctive genomic hallmark is found, there is no CLL-specific genomic aberration. Traditional cytogenetic evaluation through chromosome banding was not useful in detecting genomic aberrations in CLL cases due to the low mitotic rate. The application of fluorescence in situ hybridization (FISH) technique demonstrated that genomic aberrations can be identified in more than 80% of CLL cases; in most cases they involve loss or gain of genetic materials while translocations are rare (Dohner 2000). The four most frequent genomic alterations are independent prognostic factors at multivariate analysis and include:
1. deletion of the long arm of chromosome 13 (del13q14): it is found in 50% of CLL cases and it is usually associated with favourable prognosis. Two non-coding microRNA genes, miR-15a and miR16-1, are located in this region and have been demonstrated to play a tumour suppressor function through BCL2 regulation (Cimmino 2005);
2. trisomy 12 (+12): detected in 10-20% of cases, often as unique alteration, in the original hierarchical prognostic model by Dohner et al. (Dohner 2000) was classified as an intermediate prognosis marker. This alteration remains ill-defined, though potential candidate genes upregulated through a gene dosage effect have been identified and include P27, CDK4, HIP1R, MYF6 and MDM2 (Winkler 2005). Recent next generation sequencing studies have demonstrated an association with NOTCH1 mutation (see 2.5 «Next generation sequencing») (Del Giudice 2012; Balatti 2012; Lopez 2012);
3. deletion of the long arm of chromosome 11 (del11q22-q23): found in 5-20% of CLL patients, it is highly variable in size and it is associated with dismal prognosis. The ataxia-teleangectasia (ATM) gene, a known tumour suppressor gene, is located in this region and is affected by the deletion (Stankovic 1999). Larger deletions include also other potentially relevant genes like BIRC3, recently identified as genetic abnormality in refractory CLL cases (Rossi 2012a);
4. deletion of the short arm of chromosome 17 (del17p13): this alteration is usually detected in less than 10% of CLL cases at diagnosis but its prevalence increases up to 30% in refractory cases and over the disease course (Gaidano 2012). This deletion involves the tumour suppressor gene TP53. Patients bearing del17p belong to the highest risk category and usually follow a dismal clinical course.
2.4 Genomic changes
Chronic lymphocytic leukaemia cells express on their surface the B-cell receptor (BCR), where a key component is represented by surface immunoglobulins (IG). Surface IG expression is crucial for survival and functioning of normal B cells and of many B-cell lymphoproliferative disorders.
The analysis of IG gene rearrangements in CLL showed that about 50% of cases bear unmutated IG genes almost identical to the germ-line sequence (i.e., the percentage of identity of the heavy chain locus, IGHV, to the corresponding germ-line gene is >98%), while 50% of cases showed the presence of somatic mutations (identity <98%) (Fais 1998). This finding has relevant pathogenetic implications, as the process of somatic hypermutation takes place after antigen encounter in the lymph node microenviroment and suggested that the antigenic trigger could represent a tumour driver in CLL cases. In addition, the IGHV mutational status (mutated vs. unmutated) carries an independent prognostic relevance, with unmutated cases following a more aggressive clinical course (Hamblin 1999; Damle 1999). Further efforts in the immunogenetic area have also supported a plausible role for antigen recognition in CLL pathogenesis, demonstrating that unrelated CLL cases worldwide may express highly homologous BCRs (called “stereotyped”), where CDR3 (complementarity-determining region-3) sequences, usually extremely variable, are characterised by shared amino acid motifs. Cases expressing stereotyped BCRs collectively account for 30% of all CLL and some major subsets carry also an independent prognostic significance (Agathangelidis 2012; Vardi 2014; Stamatopoulos 2007).
2.5 Next generation sequencing
The recent application of massively sequencing technologies started unravelling the high genetic and epigenetic heterogeneity in CLL. Whole-exome sequencing (WES) demonstrated the genetic variability of the disease, but also revealed novel common gene mutations, potentially involved in natural history of the disease (Puente 2011; Wang 2011; Quesada 2011; Rossi 2012b). The most frequent somatic mutations were found to be involved in critical cellular pathways including: DNA damage and cell cycle control (TP53, ATM, BIRC3) (Rossi 2012a), mRNA processing (SF3B1) (Rossi 2011), NOTCH signalling (NOTCH1) (Rossi 2012c; Villamor 2013a), and inflammatory pathways (MYD88) (Gruber 2014; Villamor 2013b). Some lesions are mutually exclusive while others co-segregate, suggesting distinct evolutionary pathways on one side, and synergistic effects on the other side (Baliakas 2014). Four alterations showed a prognostic role in larger cohorts and have been proposed to be incorporated in prognostic nomograms:
- NOTCH1: recurrently mutated in 10-15% of CLL patients, the gene encodes for a class I transmembrane protein acting as ligand-activated transcription factor involved in cell differentiation, proliferation and apoptosis. More than 90% of NOTCH1 mutations are located in exon 34 causing disruption of the PEST domain and are frequently associated with trisomy 12, unmutated IGHV gene, aggressive clinical course and increased risk of transformation to diffuse large B-cell lymphoma (so called Richter’s transformation) (Rossi 2012c; Del Poeta 2013; Rossi 2012d; Mansouri 2013).
- SF3B1: the mutation is found in 5-7% of cases at diagnosis, but its frequency increases in progressive cases and at relapse (up to 20%) (Wang 2011; Rossi 2011). SF3B1 is a component of the spliceosome and the mutations usually involve the C-terminal HEAT-repeat domain and impair the protein binding. SF3B1 mutations are associated with dismal clinical course and fludarabine-refractoriness.
- BIRC3: it is involved in apoptosis inhibition and NFκB (nuclear factor κB) regulation. The mutations generate stop codons eliminating the C terminal ring domain. BIRC3 mutations are more frequent in fludarabine-refractory CLL patients and are mutually exclusive with TP53 mutations.
- TP53: TP53 mutations are related to short survival and chemorefractoriness in CLL patients; 80-90% of cases bearing del17p have a TP53 mutation in the remaining allele, causing a complete functional inactivation of p53 pathway. These mutations are more frequent in unmutated IGHV gene cases and independently predict a worse clinical outcome (Zenz 2008; Zenz 2009; Zenz 2010a). The prevalence of TP53 mutations are low at diagnosis, but increase over disease course.
Genome studies also revealed a wide intraclonal heterogeneity, with different CLL subpopulations being present in variable proportion in the same patient over time (Landau 2013; Schuh 2012). In general the number of genomic alterations tends to increase over disease course and it is strongly influenced by treatments, frequently conditioning clonal evolution. Mutated subclones, already detectable in minor proportion at diagnosis or before starting therapy, become more prevalent in the leukaemic populations at relapse, likely conditioning a more aggressive course of the disease (Gruber 2014; Rossi 2014).
3.1 IWCLL 2008 diagnostic criteria
According to the International Workshop on Chronic Lymphocytic Leukaemia (IWCLL) 2008 (Hallek 2008), updating the National Cancer Institute-Working Group (NCI-WG) 1996 guidelines (Cheson 1996), CLL diagnosis requires the following criteria:
1. the presence of at least 5×109 B lymphocytes/L in the peripheral blood;
2. a peculiar immunophenotypic profile as detected by flow cytometry, showing:
- a. clonal light chain restriction (either kappa or lambda);
- b. CD5 expression;
- c. CD23 expression;
- d. low levels of CD20, CD79b and surface immunoglobulin expression.
Small lymphocytic lymphoma diagnosis requires less than 5×109 B lymphocytes/L in the peripheral blood and the presence of lymphoadenopathies and/or splenomegaly and, whenever possible, should be confirmed by histopathology evaluation.
The presence of less than 5×109 B lymphocytes/L in the peripheral blood, in the absence of lymphoadenopathies or hepatosplenomegaly or disease-related cytopoenias or B symptoms, defines the condition known as monoclonal B-cell lymphocytosis.
In the absence of cytopoenias, bone marrow evaluation is no longer required for CLL/SLL diagnosis, while it is part of the pretreatment staging evaluation and it is required to confirm complete remission at the end of treatment.
3.2 Clinical presentation
Most patients are asymptomatic at diagnosis and the disease is detected due to increased lymphocyte count at blood evaluations performed for unrelated reasons. In some cases the clinical presentation is characterised by palpable lymphoadenopathies and/or splenomegaly that warrant further investigations.
B symptoms (fever of unknown origin higher than 100.5°F or 38.0°C for ≥2 weeks without other evidence of infection; unintentional weight loss of 10% or more within the previous 6 months; or night sweats for more than 1 month without evidence of infection) are rarely present. Advanced stage patients can show fatigue and intolerance to physical exercise due to anaemia, secondary to bone marrow infiltration, while the presence of bleeding manifestations due to low platelet count is very rare.
Chronic lymphocytic leukaemia per se confers a higher vulnerability to infections, explained by immune defects in humoral and cell-mediated immunity. Abnormalities in T-cell subsets and neutrophil-monocyte functions, along with hypogammaglobulinemia, are frequently detected. The latter is virtually found in all patients at some point of the disease course and is more pronounced in advanced stages (Morrison 2010). Disease-associated reduced immune function does not improve after effective treatment and it is actually worsened by the majority of available immunochemotherapeutic regimens. Bacterial infections involving upper and lower respiratory tract and urinary tract are the most frequent manifestations, though an increased risk of viral reactivation (e.g., herpes zoster infection) has been also reported. Advanced disease is frequently characterised by worsening infectious complications, also due to previous treatments and representing the main cause of death.
Chronic lymphocytic leukaemia is associated with autoimmune manifestations, in most cases directed against hematopoietic cells. Autoimmune haemolytic anaemia (AIHA) is the most frequent (10-25%) autoimmune manifestation, followed by immune thrombocytopoenia (ITP, 1-5%). Pure red cell aplasia (PRCA) and autoimmune neutropoenia are very rare disease-related manifestations (<1% and 0.2% of cases, respectively) (Hodgson 2011). It should be noted that autoantibodies against red blood cells or platelet membrane antigens are synthesised by non-malignant B cell clones and have been related to a profound immune system dysregulation due to CLL (Zent 2010; Strati 2011). Paraneoplastic pemphigus, acquired angioedema, and cold agglutinin disease are rare non-haematologic autoimmune complications of CLL (Dearden 2008).
At variance with other leukaemias (in particular, acute myeloid leukaemia), the high absolute lymphocyte count (i.e., hyperleukocytosis, frequently detected in CLL patients) does not cause signs or symptoms of leukostasis and does not require therapeutic intervention.
3.3 Differential diagnosis
The presence of a high lymphocyte count prompts for 2 main differential diagnosis:
- reactive conditions: viral infections, usually characterised by the transiency of this phenomenon, in some cases (e.g., EBV, CMV infections) diagnosed by serological evaluation;
- other lymphoproliferative disorders.
The latter category include lymphomas in leukaemic phase, e.g., mantle cell lymphoma (MCL), splenic marginal zone lymphoma (SMZL), follicular lymphoma (FL) and other leukaemias (such as hairy cell leukaemia – HCL, and B-cell prolymphocytic leukaemia – PLL). This distinction is based on several laboratory evaluations, including – but not limited to – morphology, flow cytometry and FISH analysis (Table 2).
Table 2. Differential diagnosis for CLL.
|Pleomorphic PB infiltration, predominantly represented by medium size lymphocytes with more abundant cytoplasm||Presence of villous lymphocytes in some cases (peripheral blood smear)||>55% prolymphocytes (peripheral blood smear)|
|Usually CD5+, but CD23 negative||Rarely CD5 and CD23 positive (never in the bone marrow)||Usually CD5 positive, CD23 negative, FMC7 bright|
|Cyclin D1 positive||Usually characterised by splenomegaly||Usually characterised by prominent splenomegaly|
3.4 Monoclonal B cell lymphocytosis
This recently defined condition is diagnosed based on the absence of disease related signs or symptoms, no palpable lymphoadenopathies nor hepatosplenomegaly and the presence of a CLL-like clonal B-cell population with less than 5×109 B lymphocytes/L. In the case of lower lymphocytes concentrations (<0.5×109/L), a laboratory abnormality – not an overt disease – should be considered; on the contrary, cases with higher B lymphocyte count (>0.5×109/L) carry a risk of progression into CLL requiring treatment of 1-2% per year (Shanafelt 2009b; Rossi 2009; Molica 2011; Scarfò 2012; Dagklis 2009; Fazi 2011). For this reason, international guidelines and expert panels recommend that subjects with MBL should be followed up lifelong with complete blood cell count and clinical evaluation every 6-12 months (Shanafelt 2010).
4.1 Clinical staging
Two staging systems are currently applied in CLL patients to define disease burden and treatment indication: Rai (Rai 1975) and Binet (Binet 1981) staging system. These two time-honoured systems have many advantages as they are easy to define, being based only on complete blood cell count (CBC) and physical examination, and they have been shown to be powerful prognostic indicators.
1. Rai staging system: the original classification proposed in 1975 differentiates 5 groups based on progressively shorter overall survival (Table 3).
Table 3. Rai staging system.
|0||only lymphocytosis in the peripheral blood and bone marrow infiltration||>150 months|
|I||presence of lymphoadenopathies||101 months|
|II||presence of hepatosplenomegaly||71 months|
|III||presence of anaemia (defined as Hb19 months|
|IV||presence of thrombocytopenia (Plt 3)||19 months|
The system has been later revised and risk categories has been adapted as shown in Table 4.
Table 4. Revision of Rai staging system.
|Low risk||only lymphocytosis in the peripheral blood and bone marrow infiltration (same as stage 0)|
|Intermediate risk||presence of lymphoadenopathies|
|High risk||presence of anaemia (same as stage III) and or thrombocytopoenia (same as stage IV)|
2. Binet staging system: it defines 3 different risk category based on the number of lymphoid sites involved at physical exam (cervical, axillary and inguinal nodes, hepatomegaly, splenomegaly) and the CBC values (Table 5).
Table 5. Binet staging system.
|A||no anaemia (Hb>10 g/dl) or thrombocytopoenia (Plt >100 000/mm3) and up to 2 lymphoid sites involved|
|B||no anaemia (Hb>10 g/dl) or thrombocytopoenia (Plt >100 000/mm3) and more than 2 lymphoid sites involved|
|C||presence of anaemia (Hb 3) regardless the number of lymphoid sites involved|
5.1 Natural history
The clinical course of CLL patients is extremely heterogeneous and the rough data of a median overall survival of 10 years is not able to capture the clinical variety of the disease, as survival ranges from few months to decades. On the one hand, about one third of patients never require treatment, are regularly followed up over time, and die “with” CLL rather than “because of” the disease. On the other hand, about the same proportion has to be treated at, or shortly after, diagnosis due to anaemia, thrombocytopoenia and/or bulky lymphoadenopathies and/or splenomegaly and has a reduced life expectancy (around 2-3 years). Finally, roughly one third of patients develop disease-related signs and symptoms and require treatment at variable time-length from the diagnosis.
Available treatments can often induce disease remission, but they are not able to reach the cure and CLL still remains an incurable disease in virtually all cases. According to published data, derived from alkylating-based chemotherapeutic approaches, there is no benefit in early treatment, and recent biological studies support this notion giving us some hints that early chemotherapy could actually be detrimental and be involved in the selection of resistant clones occurring at disease relapse.
Nowadays there are no prognostic factors able to discriminate CLL patients who will eventually progress at diagnosis. For this reason, long-term follow up is advised once a CLL diagnosis is established. Prognostication in CLL is an active research field and many studies tried to define not only prognostic markers able to predict the clinical course at diagnosis, but also predictive markers able to predict response to treatment thus potentially influencing treatment choices.
5.2 Traditional prognostic factors
Traditional prognostic factors include clinical parameters, laboratory data and biological factors that have been demonstrated to be differentially present in low and high-risk disease (Furman 2010; Chiorazzi 2012).
Among traditional clinical prognostic factors, Rai and Binet staging systems and lymphocyte doubling time (LDT, i.e., the time required for doubling the absolute lymphocyte count) are the most widely applied and are also reported as indication for treatment. Early stages, according to Rai and or Binet classifications, have longer overall survival, while a LDT less than 6 or, in some series, 12 months is frequently associated with disease progression (Molica 1990). Several clinical and laboratory factors have been claimed in the past as relevant prognostic factors, but many of them (e.g., pattern of bone marrow infiltration, β2 microglobulin, serum timidin-kinase, soluble CD23) are related to the disease burden and can be confounding at diagnosis.
5.3 Novel prognostic factors
In the last 15 years biological markers have been identified allowing a risk stratification of CLL patients at diagnosis and they currently are in widespread use in clinical practice. It should be emphasised that, among them, only the presence of del17p by FISH and TP53 mutations, assessed at disease progression, influence clinical management of CLL patients (Stilgenbauer 2010).
Biological prognostic factors include:
1. FISH analysis: the four most frequently detected alterations bear also a prognostic value (Dohner 2000):
a. Del13q14: this aberration carries a favourable prognostic value as CLL patients bearing this abnormality show a better prognosis than those with normal (i.e., without FISH detected abnormalities) karyotype;
b. Trisomy 12: it is associated with a less favourable clinical course and with a somewhat shorter survival than patients with normal FISH panel;
c. Del11q22-23: patients carrying this abnormality often show bulky lymphoadenopathies and aggressive clinical course, with reduced overall survival;
d. Del17p13: as mentioned, this alteration involves the tumour suppressor gene TP53, and in more than 80% of cases is associated with TP53 mutation on the remaining allele. This aberration is associated with a dire clinical outcome, being linked to fludarabine-refractoriness, treatment resistance and early disease relapse (Zenz 2010b).
2. IGHV gene mutations: several studies clearly demonstrated an association between unmutated IGHV genes and poor clinical outcome. This prognostic value was reported for the first time 15 years ago; at that time the technique applied for IGHV gene sequencing was considered expensive, cumbersome and time-consuming, and different surrogate markers, more easily determined by flow-cytometry analysis (e.g., CD38 (Damle 1999), CD49d (Gattei 2008) and ZAP70 (Crespo 2003)), have been proposed, but none of them have replaced the relevance of the IGHV mutational status.
3. TP53 mutation: though the mutation of TP53 is frequently combined with del17p, about 5% of untreated CLL patients with progressive disease requiring treatment bear a TP53 mutation without a del17p. Recent guidelines strongly suggest to integrate TP53 mutation analysis in the diagnostic work-up of CLL patients before starting treatment together with del17p assessed by FISH (Pospisilova 2012).
CD38 (a cell surface protein involved in the interaction with the microenvironment), CD49d (the integrin alpha 4 subunit of VLA-4 receptor), and ZAP70 (an intracellular kinase) have been proposed as independent prognostic markers, based on several prospective clinical trials and retrospective data collection studies demonstrating that a higher level of CD38 (more than 7, 20 or 30% in different series) (Ghia 2003; Malavasi 2011), of CD49d (more than 30%) (Dal Bo 2014) and of ZAP70 (more than 20%) (Rassenti 2004) were associated with worse prognosis. Technical issues impaired the standardisation of ZAP70 (an intranuclear marker) detected by flow cytometry; this marker is not any longer included in the work up evaluation.
Novel gene mutations that appear to be relevant in the relapsed/refractory disease setting have been detected by next generation sequencing along with the above-cited TP53 mutations, and include:
1. NOTCH1: its mutations showed a negative impact in overall survival in several cohorts and were associated with an increased risk of Richter’s transformation (Fabbri 2011). CLL patients with NOTCH1 mutations did not benefit from the addition of rituximab to fludarabine and cyclophosphamide combination (see 6 «Treatment») (Stilgenbauer 2014), while a longer progression-free survival was demonstrated when treated with alemtuzumab (Schnaiter 2013);
2. SF3B1: its mutation showed a negative effect on overall survival (Rossi 2011);
3. BIRC3: its mutations are associated with a very dismal prognosis, similar to that of TP53 mutated patients (Rossi 2012a).
It should be noted that for patients requiring treatment response to therapy is per se the most powerful prognostic indicator for survival. Patients obtaining a complete response to treatment usually fare better than those with a partial response. As more effective treatment options are now available, recent clinical trials have demonstrated that reaching so-called minimal residual disease (MRD) negativity predicts longer progression-free and overall survival (Ghia 2012) (see 6.8 «Significance of minimal residual disease (MRD)»).
6.1 Treatment guidelines
The main issues in the management of CLL patients are related to the timing (when?) and with the choice (how?) of treatment (Ghia 2014).
International guidelines clearly specify that treatment indication is based on the presence of active disease (Table 6).
Table 6. Treatment indications.
|Early stage disease (Rai 0, Binet A)||Monitoring without receiving therapy until disease progression|
|Intermediate stage (Rai I and II, Binet B)||Monitoring until signs or symptoms of active disease|
|Advanced stage (Rai III and IV, Binet C)||Treatment required|
The following signs and/or symptoms define active disease (Hallek 2008):
- Progressive bone marrow failure, demonstrated by occurrence or worsening of anaemia and/or thrombocytopoenia due to bone marrow infiltration;
- Bulky disease, demonstrated by massive (>10 cm) or rapidly progressive lymphoadenopathies and/or massive (>6 cm bellow left costal margin) or rapidly progressive splenomegaly;
- Uncontrolled autoimmune cytopoenias, defined as autoimmune anaemia and/or thrombocytopoenia not responsive to steroid treatment;
- Rapid LDT, defined by being <6 months or by an >50% increase in ≤2 months;
- Presence of B symptoms, including unintentional weight loss ≥10% in the last 6 months, fever >38.0°C for ≥2 weeks without infections, drenching night sweats for >1 month, extreme fatigue (ECOG performance status 2 or worse).
Guideline interpretation should be carefully done and some caveats should be highlighted:
- in patients with <30×109 lymphocytes/L, the LDT should not be used as single parameter to define disease progression requiring treatment;
- the absolute lymphocyte count (ALC) has no value in defining treatment indication as CLL patients can reach markedly elevated ALC without experiencing signs or symptoms of leukostasis;
- the presence of hypogammaglobulinemia and/or of a monoclonal component and/or frequent infection complications is not relevant in defining treatment indication.
6.2 Response criteria
Standardised response criteria include the following categories (Hallek 2008):
- complete response (CR): complete disappearance of disease at clinical level (including bone marrow evaluation);
- partial response (PR): reduction of 50% or more in the disease burden, with CLL being still detectable at clinical evaluation;
- stable disease (SD): patients who did not achieve at least a PR and did not fulfil PD definition (i.e., disease burden showed less than 50% increase or reduction);
- progressive disease (PD): increase of 50% or more in the disease burden.
Clinically beneficial responses include CR and PR, while SD and PD should be considered treatment failures.
Table 7 reports the extended IWCLL 2008 criteria for defining the quality of responses.
Table 7. IWCLL 2008 Response criteria.
|Lymphoadenopathies||None >1.5 cm||Decrease ≥50%||Increase ≥50%|
|Hepatosplenomegaly||None||Decrease ≥50%||Increase ≥50%|
|ALC||<4,000/μl||Decrease ≥50%||Increase ≥50%|
|Bone marrow||Normocellular, 30% lymphocytes, no
Hypocellular marrow defines Cri
|50% reduction in marrow infiltrate, or B-lymphoid nodules|
|Platelet count||>100,000/μl||>100,000/μl or increase ≥50% over baseline||Decrease of ≥50% from baseline
secondary to CLL
|Haemoglobin||>11 g/dl||>11 g/dL or increase; ≥50% over baseline||Decrease of ≥50% from baseline
secondary to CLL
|Neutrophils||>1,500/μl||>1,500/μl or >50% improvement over baseline|
|CR: complete response; PR: partial response; PD: progressive disease; CR: complete response with incomplete bone marrow recovery.|
6.3 Treatment options
The treatment choice requires a careful evaluation of different factors including:
1. patient fitness status based on multidimensional geriatric assessment (i.e., the comorbidity burden and the performance status, along with the functional and mental status and the need for caregiver);
2. the genetic profile (i.e., the presence vs. absence of TP53 alterations, detected by FISH and/or by mutation analysis);
3. the disease status (first-line treatment vs. ≥2 line of treatment; relapse vs. refractoriness to last treatment) (Ghia 2014).
6.4 First-line treatment
a. Fit or go-go patients: CLL patients are defined as “fit” or “go-go” by a normal renal function (creatinine clearance >70 ml/min) and no or few comorbidities (usually rated on a comorbidity index of rating scale – CIRS – score of 6 or less). These subjects, if experiencing progressive disease, are candidates to receive a chemoimmunotherapy combination with fludarabine, cyclophosphamide and rituximab (FCR), currently considered the standard of care. After preliminary results derived from phase II studies in US (Keating 2005), thanks to a European phase III study (CLL8) (Hallek 2010) chaired by the German CLL Study Group (GCLLSG), this treatment has been demonstrated to reach high response rate (overall response rate 90%, with complete response 40%) and to confer a significant advantage in terms of progression-free and overall survival in comparison to the standard regimen FC (fludarabine and cyclophosphamide), becoming the new standard of care. Updated results based on longer follow up have shown that a relevant proportion of patients remain without detectable disease 10 years after the end of treatment. This impressive result comes at a price, as the randomised study described a higher incidence of grade 3-4 neutropoenia (though apparently not associated with an increase in the infection risk) (Hallek 2010), and follow up studies described a more frequent occurrence of bacterial and viral infections for 2 years after treatment completion (Tam 2008). In addition, there are some concerns on the potential toxicity of this combination for bone marrow precursors and, though most clinical trials did not show an increase in the risk of therapy related myelodysplasia and/or acute myeloid leukaemia, the occurrence of late onset cytopoenias (mainly neutropoenia) is not rarely reported (Strati 2013b). It is now actively debated if the standard treatment scheme, including 6 courses, can be safely reduced to 3 or 4 cycles based on the minimal residual disease (MRD) evaluation aiming at reducing toxicity without compromising efficacy (Strati 2014). Preliminary results from a retrospective analysis recently suggested that three FCR courses can be effective if achieving MRD status and prompted randomised MRD-guided prospective clinical trials. It is worth noting that most patients enrolled in the CLL8 phase III trial were younger than 70 years, and the tolerance in fit patients older than 70 years was quite poor, requiring early treatment stop and/or dose reduction due to adverse events in many cases. Alternative treatment options for first-line treatment in this category include the use of bendamustine+rituximab (BR) (Fischer 2012). This combination has been recently compared with FCR in a randomised GCLLSG trial (CLL10) and showed a better tolerance for BR, but a lower rate of complete response and an overall shorter progression-free survival in comparison to FCR though apparently non confirmed among individuals >65 years of age (Eichhorst 2013).
b. Unfit or slow go: “Unfit” or “slow go” patients are characterised by a relevant comorbidity burden (CIRS score >6) and/or impaired renal function (creatinine clearance <70 ml/min). This category includes the vast majority of CLL patients, considering the median age at diagnosis and the fact that patients might need treatment even years after the diagnosis. In Europe, these patients were usually treated with the alkylating agent chlorambucil in monotherapy. This strategy has several advantages, including oral administration, low cost and good tolerability. Nevertheless, this drug is associated with a low rate of response (with anecdotal or no CRs) and a short PFS and seems to increase the long-term risk of therapy-related myelodysplasia and/or acute myeloid leukaemia. Further attempts were pursued to improve disease control replacing chlorambucil with purine analogues, in particular fludarabine; but, though an increase in response rate and complete response rate have been demonstrated, elderly patients treated with fludarabine fare worse than those treated with chlorambucil in terms of overall survival (Eichhorst 2009). These findings led to phase III studies testing the combination of chlorambucil with anti-CD20 antibodies; this strategy has been able to significantly improve response rate and progression-free survival, maintaining a favourable side-effect profile (Goede 2014). The main toxicity associated with anti-CD20 administration was due to infusion-related reactions, mainly grade 1 and 2, and more frequent with the first or second infusion, and an increase in grade 3 and 4 neutropoenia without increasing the infection risk. The depth of response was greatly improved and the combinations of both chlorambucil+obinutuzumab and chlorambucil+ofatumumab were able to reach minimal residual disease negative remissions in almost 20% and more than 10% of cases, respectively (Goede 2014; Hillmen 2013). Based on these results, both anti-CD20 antibodies have been recently approved for first-line treatment of CLL patients in combination with chlorambucil. Considering that the process of ageing is extremely heterogeneous and that nowadays many elderly patients maintain a very good performance status, more intensive treatment combinations have been tested in this population. Among them, the most widely applied are FCR-Lite (Foon 2009), a regimen where the doses of fludarabine and cyclophosphamide have been reduced to improve tolerability, the combination of pentostatine, cyclophosphamide and rituximab (PCR) (Kay 2007; Shanafelt 2007), and the use of bendamustine monotherapy or in combination with rituximab (Fischer 2012; Knauf 2009). Though preliminary results are promising, these combinations still need to be validated in randomised, prospective clinical trials in this category of patients.
c. High-risk: this category is mainly represented by CLL patients bearing del17p and/or TP53 mutations (Stilgenbauer 2010). It should be noted that the presence of these aberrations per se does not represent an indication for treatment, as a proportion of patients with these aberrations (mainly associated with mutated IGHV genes) follow an indolent clinical course (Best 2009). If these alterations are detected in patients with progressive disease requiring treatment, they are associated with a dismal prognosis and there are no standard treatments able to overcome this adverse clinical course. For this reason, it is strongly recommended that patients carrying these abnormalities are enrolled in clinical trials with novel agents, acting independently from the TP53 pathway. For these patients, allogeneic stem cell transplantation should be considered early during disease course, as most of the effective treatments are able to obtain short-lasting responses (mainly PR) at best. Different debulking strategies are currently applied in order to reduce disease burden. In some cases FCR is administered, as a significant proportion of these patients respond, though only partially, but relapse early. Patients can also benefit from alemtuzumab-based combinations, though the response duration is still short. The combination of alemtuzumab and high-dose steroids was found to be very effective in this population with an ORR up to 90% and a CR rate up to 65% (Pettitt 2006; Pettitt 2012). More intensive combinations based on the addition of cyclophosphamide and/or fludarabine to alemtuzumab have been demonstrated to be associated with unacceptably high infection rate and treatment-related mortality (Lepretre 2012). The addition of alemtuzumab or mitoxanthrone to FCR did not lead to a significant improvement in ORR, while causing more frequent bone marrow toxicities and infectious complications (Parikh 2011; Bosch 2009).
More recently, novel kinase inhibitors have been approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) in first-line for patients with 17p deletion (if chemotherapy is contraindicated) and they are going to turn around the CLL treatment algorithm in this category of patients in the near future. The approved agents include:
- Ibrutinib: this oral compound (420 mg once daily) irreversibly inhibits BTK (Bruton-tirosine kinase), a key component downstream to the B-cell Receptor (BCR) pathway. BTK activity is required for calcium release, activation of the NFκB and NFAT pathways. Ibrutinib irreversible bond to BTK at the C481 residue causes kinase function inactivation and it is able to induce modest CLL cell apoptosis and block of proliferation and B-cell receptor signalling in vitro. In CLL patients, the compound is administered at 420 mg once-daily dose. Main side effects include diarrhoea, bleeding manifestations and CYP3A4 interactions contraindicating the concurrent administration of strong inhibitors or inducers of cytochrome p450 (O’Brien 2014; Byrd 2013; Byrd 2014). It has also been approved for the use in relapsed/refractory CLL patients (see 6.5 «Treatment for relapsed and refractory CLL»).
- Idelalisib: it is an orally administered PI3Kδ inhibitor (150 mg twice daily). PI3Kδ is the isoform preferentially expressed in normal and leukaemic B lymphocytes where it is involved in proliferation and survival. Activation of PI3K requires LYN-dependent phosphorylation of CD19, a B cell-specific cell surface molecule. After BCR triggering, the cytoplasmic domain of CD19 is phosphorylated by LYN, leading to PI3K binding and then production of the lipid phosphatidylinositol-3,4,5-triphosphate (PIP3). PIP3 activates several BCR signalling components, in particular the serine/threonine protein kinase AKT. Idelalisib has been approved in combination with rituximab also for relapsed/refractory CLL beside in first line treatment of patients carrying deletion 17p (Furman 2014). Transaminase elevation, drug-related pneumonitis and colitis (including early and late-onset diarrhoea) were reported as principal side effects. In most cases these adverse events were reversible after drug interruption and/or corticosteroids treatment and they usually did not occur again restarting the drug at the same or at lower dose after complete recovery (Brown 2014; Flinn 2014).
6.5 Treatment for relapsed and refractory CLL
There is no standard treatment for relapsing patients and the regimen choice is mainly based on response duration to first-line treatment, patient fitness and side effects experienced with previous therapy. Patients with refractory disease and/or unfavourable genetic abnormalities should be always considered for enrolment in clinical trials including or not stem cell transplantation.
In everyday practice, patients treated with first-line immunochemotherapy combinations, experiencing a response duration of more than 24-36 months, should receive the same combinations (Ghia 2014). Attention should be paid to cumulative bone marrow toxicity in patients receiving FCR as first-line treatment as few data are available.
Patients relapsing within 24-36 months after the end of treatment and refractory patients (defined as those with stable or progressive disease after treatment or relapsing within 6 months after completing a fludarabine-based combination) represent a clinical challenge and should always be considered for enrolment in clinical trials. Of course, they should not be retreated with the first-line regimen and evaluation of response should be carefully performed in order to early interrupt ineffective treatment and avoid meaningless toxicities. The most frequently applied options till recently included:
- alemtuzumab-based combinations: the combination of fludarabine and alemtuzumab has been tested in phase II clinical trials where it was able to reach more than 80% of responses and 30% CRs (Elter 2011; Elter 2005; Kennedy 2002);
- high-dose steroids associated with anti-CD20 monoclonal antibody: the combination of methylprednisolone (1 g/mq for 3 to 5 days) in association with dose-dense rituximab (rituximab 375 mg/mq days 1,8,15) every 4 weeks showed valuable response rate also in the relapsed/refractory setting and in particular in patients bearing TP53 abnormalities (Castro 2008).
The novel kinase inhibitors ibrutinib and idelalisib (plus rituximab) have also been approved in the relapsed/refractory setting (Byrd 2014; Furman 2014). They are rapidly effective in lymph node shrinkage and this reduction is frequently associated with the occurrence of so-called redistribution lymphocytosis, that it is thought to be related to a compartment shift of CLL cells.
- Ibrutinib: it showed impressive overall response rate in the relapsed/refractory setting also in patients with high-risk disease (up to 88% PFS and 90% OS at 6 months).
- Idelalisib: it showed great efficacy when combined with rituximab, in particular in patients bearing del17p and/or TP53 mutations (Furman 2014).
- Ofatumumab, a second-generation anti-CD20 monoclonal antibody, has been approved for patients with CLL refractory to both purine analog and alemtuzumab (so-called double-refractory CLL) (Wierda 2010). This drug, targeting a different epitope of CD20, demonstrated a slower dissociation rate (making it more effective against cells characterized by low levels of CD20 expression, like CLL cells) and it is more potent at inducing complement-dependent cytotoxicity in comparison to rituximab. It was able to obtain more than 50% of responses in double-refractory patients, being generally well tolerated, but the median duration of response was less than 6 months.
6.6 Experimental agents
Beside the recently approved agents, in the last other novel exciting treatment approaches started being tested in the CLL field, raising further hope that we are getting closer to a chemo-free strategy for CLL patients aiming at cure.
In advanced clinical development, other kinase inhibitors are:
- IPI-145: this is an orally available inhibitor of PI3Kγ and δ isoforms (Flinn 2013), demonstrating up to 50% ORR in phase I studies and now tested in phase II and III clinical trials (Cancer Discov 2014);
- second- and third-generation BTK inhibitors: including CC-292, ONO-4059, ACP-196;
- CDK inhibitors: the first-generation compound, flavopiridol, and its next-in line drug, dinaciclib, showed promising response rates in patients with relapsed disease associated with an increase in the risk of tumour lysis syndrome occurrence, but their clinical development for CLL was recently stopped.
Promising novel drugs acting with different pathogenesis-related mechanisms are:
- ABT-199: this is a third-generation BCL2 inhibitor, designed to overcome the limitations of previous BCL2 family inhibitors. It is orally available, shows a selective BCL2 inhibition profile without interfering with BCLXL and therefore not causing relevant thrombocytopoenia. Phase I and II clinical trials were amended after detecting a high risk of tumour lysis syndrome (rarely seen in CLL), introducing a lead-in dose followed by a dose-escalation phase that showed impressive ORR and CR response rate including achievement of MRD negativity status in monotherapy in relapsed/refractory patients (Seymour 2013);
- Lenalidomide: this oral compound, commercially available for the treatment of multiple myeloma and lymphomas, was successfully administered also in CLL patients (Badoux 2011; Kater 2014; Strati 2013). The mechanism of action is not clearly understood, but it is thought to be based on its immunomodulatory effects. Main side effects include: neutropoenia, a CLL-specific tumour flare reaction (characterised by the painful enlargement of nodal sites involved by the disease) and increased thrombotic risk requiring prophylactic therapy.
6.7 Allogeneic stem cell transplantation
Autologous stem cell transplantation is no longer considered suitable for the treatment of CLL patients, being associated with relevant toxicities without significant advantages in terms of progression-free and overall survival when compared to immunochemotherapy regimens (i.e., FCR). The advent of novel kinase inhibitors, next-generation monoclonal antibodies and immunomodulatory agents is changing the treatment paradigm for CLL patients. As information on long-term safety and efficacy of these novel agents is still lacking, recently updated EBMT recommendations reported that allogeneic stem cell transplantation should be strongly considered in fit patients showing refractory disease and/or bearing TP53 aberrations (Dreger 2014). Patients with high-risk CLL should be offered the chance to receive novel agents and, when the maximum response is reached, two main options should be considered:
1. to consolidate the result performing an allogeneic stem cell transplantation;
2. to continue treatment with novel agents until progression and delay the transplant procedure at the next-treatment line.
The transplant procedure should be carefully discussed with the patients, considering that early transplantation in high-risk CLL is supported by the coexistence of relapsed/refractory CLL and unfavourable genetic abnormalities (del17, TP53 mutation, del11q), a younger age and the absence of relevant comorbidities, and the availability of a well-matched donor. Several studies using reduced-intensity conditioning (RIC) allo-SCT have demonstrated event-free-survival (EFS) and overall survival (OS) rates of 35-45% and 50-60% at 5 years (Böttcher 2011; Schetelig 2008). Five-year survival for patients with sensitive and non-bulky disease is between 54% and 79%, and up to 50% of patients can reach MRD negativity after transplant. The disease control after allo-SCT is not influenced by the IGHV gene status or TP53 dysfunction or purine analogue-refractoriness. Current RIC approaches are less toxic and recent studies have demonstrated a reduced early mortality (<5%), but the overall non-relapse mortality is still high (up to 15-30%) in the CLL setting particularly related to acute and chronic graft versus host disease (GVHD). Chronic GVHD represents a relevant concern as it is affecting the quality of life in at least 25% of surviving patients.
6.8 Significance of minimal residual disease (MRD)
As more effective treatment strategies are becoming available, the disease eradication becomes an achievable goal. International guidelines define minimal residual disease negativity as the presence of less than 1 CLL cell among 100.000 leukocytes (10-4) detected through quantitative PCR or multi-colour flow cytometry analysis. Several studies demonstrated that MRD negativity is a powerful predictor of progression-free and overall survival, the latter in particular when using FCR (Böttcher 2012) or alemtuzumab (Lin 2010), and it may become a desirable goal for the treatment strategy in young fit CLL patients. Nowadays, MRD evaluation is not recommended in routine clinical practice but it is included in most recent ongoing clinical trials with a twofold aim:
1. to validate a surrogate marker for progression-free and overall survival;
2. to define a reliable parameter able to guide treatment decisions (further treatment vs. early stop vs. maintenance) to avoid overtreatment on the one side and to delay clinically evident relapse on the other side.
7. LATE SEQUELAE
7.1 Infection risk
Patients affected by CLL are at increased risk of developing infectious complications and the risk is increased if they receive treatment for the disease. Increased infectious risk is related to immune defects inherent to CLL as well as to therapy-related immunosuppression (Morrison 2010). The spectrum of infections changes according to the chosen regimen, e.g., purine analogues, monoclonal antibodies (alemtuzumab and rituximab), alkylating agents or combinations of these drugs. Bacterial infections are the most common, but fungal and herpesvirus infections are also frequent with the use of these agents. An increased risk for bacterial infections and herpetic reactivation has been demonstrated for up to 2 years after intensive immunochemotherapy combinations like FCR. Though patients with hypogammaglobulinemia and frequent, relevant infectious episodes benefit from prophylactic intravenous immunoglobulin support, this treatment does not seem to be cost-effective in patients without clinically relevant infections. Monoclonal antibodies (in particular rituximab and alemtuzumab) administration is very rarely complicated by a usually fatal neurologic syndrome called progressive multifocal leucoencefalopathy, that is a viral disease caused by JC virus reactivation and characterised by a progressive inflammation of the white matter (Isidoro 2014). The use of vaccination strategies, including vaccines for pneumococcus, influenza, haemophilus, tetanus, typhoid and diphtheria, has been evaluated in CLL patients. As immunization responses may be suboptimal due to impaired antibody production as well as defects in antigen presentation it has been proposed that responses may be stronger and more persistent with protein and conjugated vaccines than with polysaccharide vaccines. As available information is scanty, consensus recommendations on this matter are still lacking.
7.2 Second cancers
Patients affected by CLL have a higher risk of developing other cancers in comparison to age- and gender-matched controls. An increased incidence of second cancers has been reported, though the relative contribution of chemoimmunotherapy regimens remains still unknown. As the distribution of second cancers in CLL is similar to what is found in solid organ or autologous stem cell transplant recipients (with particularly increased incidence of malignant melanoma, soft-tissue sarcomas and lung cancer), a role for the immunologic defects associated with the disease has been hypothesized. Epidemiological studies found a relative risk of second cancers of 2.2, with skin, prostate, breast, melanoma, lymphoma, gastrointestinal and lung cancers being the most frequent. Second cancers were more common in older people and in male. In addition to an increased risk of occurrence, CLL diagnosis seems also to confer an unfavourable prognosis in patients with second cancers. Inferior overall survival and cancer-specific survival has been demonstrated for breast, colon rectum, kidney, prostate or lung cancer in patients with pre-existing CLL. In addition to CLL-related risk, chemotherapy and/or immunochemotherapy combinations for CLL treatment have been implicated in additional risk. While purine-analogue single-agent did not seem to be associated with higher risk of developing second cancers (beside the risk related to CLL), recently it has been demonstrated that the risk of second cancers is 2.38 times higher in comparison to the general population in CLL patients treated with fludarabine, cyclophosphamide and rituximab, the current standard first-line treatment for fit patients (Benjamini 2014). Among CLL patients who developed a second cancer after FCR treatment a higher than expected rate of therapy-related acute myeloid leukaemia/myelodysplastic syndrome (t-AML/MDS) and of Richter transformation was detected (5.1% and 9%, respectively). These patients experienced a short median overall survival. The features of t-AML/MDS in CLL patients treated with FCR are consistent with t-AML/MDS related to other alkylating agents (i.e. more frequent presentation as MDS than as AML, recurrent unbalanced loss of chromosome 5 and/or 7 or complex karyotype), but showed a shorter latency (median 35 months, in comparison to historical controls treated with alkylating agents where the latency is 5-7 years), becoming even shorter (23 months) in patients with prolonged myelosuppression after FCR, where t-AML/MDS can directly emerge without complete recovery of blood cell count (Zhou 2012).
There are no clear indications about the frequency and the evaluation required for the follow-up of asymptomatic CLL patients. Patients who are candidates to a “wait and watch” approach should be applied with regular clinical and laboratory follow-up. Based on to the recently updated IWCLL2008 guidelines (Hallek 2008), neither bone marrow biopsies nor CT scans are recommended at diagnosis or during follow up, unless the disease is becoming symptomatic or progressive (Ghia 2014). After diagnosis, CLL patients are followed up at regular intervals, being shorter at the beginning, to exclude a rapid increase in the disease burden. Follow up is based on clinical evaluation and lab tests (complete blood cell count, kidney and liver function), while annual abdominal ultrasound is optional.
According to international guidelines additional tests (including CT scans and bone marrow evaluation) should be performed at disease progression.
PET/CT scan is not useful in defining the disease status in CLL patients but could be applied in subjects with suspected Richter transformation, aiming at defining the optima nodal site for biopsy.
Agathangelidis A, Darzentas N, Hadzidimitriou A, Brochet , Murray F, Yan XJ et al. Stereotyped B-cell receptors in one-third of chronic lymphocytic leukemia: a molecular classification with implications for targeted therapies. Blood 2012; 119(19): 4467-75. [Medline]
Badoux XC1, Keating MJ, Wen S, Lee BN, Sivina M, Reuben J et al. Lenalidomide as initial therapy of elderly patients with chronic lymphocytic leukemia. Blood 2011; 118(13): 3489-98. [Medline]
Balatti V, Bottoni A, Palamarchuk A, Alder H, Rassenti LZ, Kipps TJ et al. NOTCH1 mutations in CLL associated with trisomy 12. Blood 2012; 119(2): 329-31. [Medline]
Baliakas P, Hadzidimitriou A, Sutton LA, Rossi D, Minga E, Villamor N et al. Recurrent mutations refine prognosis in chronic lymphocytic leukemia. Leukemia 2014. [Epub ahead of print] [Medline]
Benjamini O, Jain P, Trinh L, Qiao W, Strom SS, Lerner Set al. Second cancers in patients with chronic lymphocytic leukemia who received frontline fludarabine, cyclophosphamide and rituximab therapy: distribution and clinical outcomes. Leuk Lymphoma 2014; 1-8. [Epub ahead of print] [Medline]
Berndt SI, Skibola CF, Joseph V, Camp NJ, Nieters A, Wang Z et al. Genome-wide association study identifies multiple risk loci for chronic lymphocytic leukemia. Nat Genet 2013; 45(8): 868-76. [Medline]
Best OG, Gardiner AC, Davis ZA, Tracy I, Ibbotson RE, Majid A et al. A subset of Binet stage A CLL patients with TP53 abnormalities and mutated IGHV genes have stable disease. Leukemia 2009; 23(1): 212-4. [Medline]
Binet JL, Auquier A, Dighiero G, Chastang C, Piguet H, Goasguen J et al. A new prognostic classification of chronic lymphocytic leukemia derived from a multivariate survival analysis. Cancer 1981; 48: 198-206. [Medline]
Boggs DR, Chen SC, Zhang ZN, Zhang A. Chronic lymphocytic leukemia in China. Am J Hematol 1987; 25(3): 349-54. [Medline]
Bosch F, Abrisqueta P, Villamor N, Terol MJ, González-Barca E, Ferra C et al. Rituximab, fludarabine, cyclophosphamide, and mitoxantrone: a new, highly active chemoimmunotherapy regimen for chronic lymphocytic leukemia. J Clin Oncol 2009; 27(27): 4578-84. [Medline]
Böttcher S, Ritgen M, Dreger P. Allogeneic stem cell transplantation for chronic lymphocytic leukemia: lessons to be learned from minimal residual disease studies. Blood Rev 2011; 25(2): 91-6. [Medline]
Böttcher S, Ritgen M, Fischer K, Stilgenbauer S, Busch RM, Fingerle-Rowson G et al. Minimal residual disease quantification is an independent predictor of progression-free and overall survival in chronic lymphocytic leukemia: a multivariate analysis from the randomized GCLLSG CLL8 trial. J Clin Oncol 2012; 30(9): 980-8. [Medline]
Brown JR, Byrd JC, Coutre SE, Benson DM, Flinn IW, Wagner-Johnston ND et al. Idelalisib, an inhibitor of phosphatidylinositol 3-kinase p110delta, for relapsed/refractory chronic lymphocytic leukemia. Blood 2014; 123(22): 3390-7. [Medline]
Byrd JC, Brown JR, O’Brien S, Barrientos JC, Kay NE, Reddy NM et al. Ibrutinib versus ofatumumab in previously treated chronic lymphoid leukemia. N Engl J Med 2014; 371(3): 213-23. [Medline]
Castro JE, Sandoval-Sus JD, Bole J, Rassenti L, Kipps TJ. Rituximab in combination with high-dose methylprednisolone for the treatment of fludarabine refractory high-risk chronic lymphocytic leukemia. Leukemia 2008; 22(11): 2048-53. [Medline]
Cheson BD, Bennett JM, Grever M, Kay N, Keating MJ, O’Brien S et al. National Cancer Institute-sponsored Working Group guidelines for chronic lymphocytic leukemia: revised guidelines for diagnosis and treatment. Blood 1996; 87(12): 4990-7. [Medline]
Chiorazzi N. Implications of new prognostic markers in chronic lymphocytic leukemia. Hematology Am Soc Hematol Educ Program 2012; 2012: 76-87. [Medline]
Cimmino A, Calin GA, Fabbri M, Iorio MV, Ferracin M, Shimizu M et al. miR-15 and miR-16 induce apoptosis by targeting BCL2. Proc Natl Acad Sci U S A 2005; 102(39): 13944-9. [Medline]
Crespo M, Bosch F, Villamor N, Bellosillo B, Colomer D, Rozman M et al. ZAP-70 expression as a surrogate for immunoglobulin-variable-region mutations in chronic lymphocytic leukemia. N Engl J Med 2003; 348(18): 1764-75. [Medline]
Crowther-Swanepoel D, Broderick P, Di Bernardo MC, Dobbins SE, Torres M, Mansouri M et al. Common variants at 2q37.3, 8q24.21, 15q21.3 and 16q24.1 influence chronic lymphocytic leukemia risk. Nat Genet 2010a; 42(2): 132-6. [Medline]
Crowther-Swanepoel D, Houlston RS. Genetic variation and risk of chronic lymphocytic leukaemia. Semin Cancer Biol 2010b; 20(6): 363-9. [Medline]
Dagklis A, Fazi C, Sala C, Cantarelli V, Scielzo C, Massacane R et al. The immunoglobulin gene repertoire of low-count chronic lymphocytic leukemia (CLL)-like monoclonal B lymphocytosis is different from CLL: diagnostic implications for clinical monitoring. Blood 2009; 114(1): 26-32. [Medline]
Dal Bo M, Tissino E, Benedetti D, Caldana C, Bomben R, Del Poeta G et al. Microenvironmental interactions in chronic lymphocytic leukemia: the master role of CD49d. Semin Hematol 2014; 51(3): 168-76. [Medline]
Damle RN, Wasil T, Fais F, Ghiotto F, Valetto A, Allen SL et al. Ig V gene mutation status and CD38 expression as novel prognostic indicators in chronic lymphocytic leukemia. Blood 1999; 94(6): 1840-7. [Medline]
Dearden C. Disease-specific complications of chronic lymphocytic leukemia. Hematology Am Soc Hematol Educ Program 2008: 450-6. [Medline]
Del Giudice I, Rossi D, Chiaretti S, Marinelli M, Tavolaro S, Gabrielli S et al. NOTCH1 mutations in +12 chronic lymphocytic leukemia (CLL) confer an unfavorable prognosis, induce a distinctive transcriptional profiling and refine the intermediate prognosis of +12 CLL. Haematologica 2012; 97(3): 437-41. [Medline]
Del Poeta G, Dal Bo, M, Del Principe MI, Pozzo E, Rossi FM, Zucchetto A et al. Clinical significance of c.7544-7545 delCT NOTCH1 mutation in chronic lymphocytic leukaemia. Br J Haematol 2013; 160(3): 415-8. [Medline]
Di Bernardo MC, Crowther-Swanepoel D, Broderick P, Webb E, Sellick G, Wild R et al. A genome-wide association study identifies six susceptibility loci for chronic lymphocytic leukemia. Nat Genet 2008; 40(10): 1204-10. [Medline]
Dohner H, Stilgenbauer S, Benner A, Leupolt E, Krober A, Bullinger L et al. Genomic aberrations and survival in chronic lymphocytic leukemia. N Engl J Med 2000; 343(26): 1910-6. [Medline]
Dreger P, Schetelig J, Andersen N, Corradini P, van Gelder M, Gribben J et al. Managing highrisk CLL during transition to a new treatment era: stem cell transplantation or novel agents? Blood 2014; 124(26): 3841-9. [Medline]
Eichhorst BF, Busch R, Stilgenbauer S, Stauch M, Bergmann MA, Ritgen M et al. First-line therapy with fludarabine compared with chlorambucil does not result in a major benefit for elderly patients with advanced chronic lymphocytic leukemia. Blood 2009; 114(16): 3382-91. [Medline]
Eichhorst B, Fink AM, Busch R, Lange E, Koppler H, Kiehl M et al. Chemoimmunotherapy with Fludarabine (F), Cyclophosphamide (C), and Rituximab (R) (FCR) versus Bendamustine and Rituximab (BR) in previously untreated and physically fit patients (pts) with advanced chronic lymphocytic leukemia (CLL): results of a planned interim analysis of the CLL10 Trial, an international, randomized study of the german CLL Study Group (GCLLSG). Blood 2013; 122(21) Suppl: abstract 526. [Abstract]
Elter T, Borchmann P, Schulz H, Reiser M, Trelle S, Schnell R et al. Fludarabine in combination with alemtuzumab is effective and feasible in patients with relapsed or refractory B-cell chronic lymphocytic leukemia: results of a phase II trial. J Clin Oncol 2005; 23(28): 7024-31. [Medline]
Elter T, Gercheva-Kyuchukova L, Pylylpenko H, Robak T, Jaksic B, Rekhtman G et al. Fludarabine plus alemtuzumab versus fludarabine alone in patients with previously treated chronic lymphocytic leukaemia: a randomised phase 3 trial. Lancet Oncol 2011; 12(13): 1204-13. [Medline]
Fabbri G, Rasi S, Rossi D, Trifonov V, Khiabanian H, Ma J et al. Analysis of the chronic lymphocytic leukemia coding genome: role of NOTCH1 mutational activation. J Exp Med 2011; 208(7): 1389-401. [Medline]
Fais F, Ghiotto F, Hashimoto S, Sellars B, Valetto A, Allen SL et al. Chronic lymphocytic leukemia B cells express restricted sets of mutated and unmutated antigen receptors. J Clin Invest 1998; 102(8): 1515-25. [Medline]
Fazi C, Scarfò L, Pecciarini L, Cottini F, Dagklis A, Janus A et al. General population low-count CLL-like MBL persists over time without clinical progression, although carrying the same cytogenetic abnormalities of CLL. Blood 2011; 118(25): 6618-25. [Medline]
Fischer K, Cramer P, Busch R, Böttcher S, Bahlo J, Schubert J et al. Bendamustine in combination with rituximab for previously untreated patients with chronic lymphocytic leukemia: a multicenter phase II trial of the German Chronic Lymphocytic Leukemia Study Group. J Clin Oncol 2012; 30(26): 3209-16. [Medline]
Flinn I, Patel M, Kahl BS et al. Preliminary Safety and Efficacy Of IPI-145, a Potent Inhibitor Of Phosphoinositide-3-Kinase-δ,γ, In Patients With Chronic Lymphocytic Leukemia. Blood 2013; 122(21) Suppl: abstract 677.
Flinn IW, Kahl BS, Leonard JP, Furman RR, Brown JR, Byrd JC et al. Idelalisib, a selective inhibitor of phosphatidylinositol 3-kinase-delta, as therapy for previously treated indolent non-Hodgkin lymphoma. Blood 2014; 123(22): 3406-13. [Medline]
Foon KA, Boyiadzis M, Land SR, Marks S, Raptis A, Pietragallo L et al. Chemoimmunotherapy with low-dose fludarabine and cyclophosphamide and high dose rituximab in previously untreated patients with chronic lymphocytic leukemia. J Clin Oncol 2009; 27(4): 498-503. [Medline]
Furman RR. Prognostic markers and stratification of chronic lymphocytic leukemia. Hematology Am Soc Hematol Educ Program 2010; 2010: 77-81. [Medline]
Furman RR, Sharman JP, Coutre SE, Cheson BD, Pagel JM, Hillmen P et al. Idelalisib and rituximab in relapsed chronic lymphocytic leukemia. N Engl J Med 2014; 370(11): 997-1007. [Medline]
Gaidano G, Foa R, Dalla-Favera R. Molecular pathogenesis of chronic lymphocytic leukemia. J Clin Invest 2012; 122(10): 3432-8. [Medline]
Gattei V, Bulian P, Del Principe MI, Zucchetto A, Maurillo L, Buccisano F et al. Relevance of CD49d protein expression as overall survival and progressive disease prognosticator in chronic lymphocytic leukemia. Blood 2008; 111(2): 865-73. [Medline]
Ghia P, Guida G, Stella S, Gottardi D, Geuna M, Strola G et al. The pattern of CD38 expression defines a distinct subset of chronic lymphocytic leukemia (CLL) patients at risk of disease progression. Blood 2003; 101(4): 1262-9. [Medline]
Ghia P. A look into the future: can minimal residual disease guide therapy and predict prognosis in chronic lymphocytic leukemia? Hematology Am Soc Hematol Educ Program 2012; 2012: 97-104. [Medline]
Ghia P, Hallek M. Management of chronic lymphocytic leukemia. Haematologica 2014; 99(6): 965-72. [Medline]
Goede V, Fischer K, Busch R, Engelke A, Eichhorst B, Wendtner CM et al. Obinutuzumab plus chlorambucil in patients with CLL and coexisting conditions. N Engl J Med 2014; 370(12): 1101-10. [Medline]
Goldin LR, Bjorkholm M, Kristinsson SY, Turesson I, Landgren O. Elevated risk of chronic lymphocytic leukemia and other indolent non-Hodgkin’s lymphomas among relatives of patients with chronic lymphocytic leukemia. Haematologica 2009; 94(5): 647-53. [Medline]
Gruber M, Wu CJ. Evolving understanding of the CLL genome. Semin Hematol 2014; 51(3): 177-87. [Medline]
Hallek M, Cheson BD, Catovsky D, Caligaris-Cappio F, Dighiero G, Döhner H et al. Guidelines for the diagnosis and treatment of chronic lymphocytic leukemia: a report from the International Workshop on Chronic Lymphocytic Leukemia updating the National Cancer Institute-Working Group 1996 guidelines. Blood 2008; 111(12): 5446-56. [Medline]
Hallek M, Fischer K, Fingerle-Rowson G, Fink AM, Busch R, Mayer J et al. Addition of rituximab to fludarabine and cyclophosphamide in patients with chronic lymphocytic leukaemia: a randomised, open-label, phase 3 trial. Lancet 2010; 376(9747): 1164-74. [Medline]
Hamblin TJ, Davis Z, Gardiner A, Oscier DG, Stevenson FK. Unmutated Ig V(H) genes are associated with a more aggressive form of chronic lymphocytic leukemia. Blood 1999; 94(6): 1848-54. [Medline]
Hillmen P, Robak T, Janssens A, et al. Ofatumumab + Chlorambucil Versus Chlorambucil Alone In Patients With Untreated Chronic Lymphocytic Leukemia (CLL): Results Of The Phase III Study Complement 1 (OMB110911). Blood 2013; 122(21) Suppl: abstract 528.
Hodgson K, Ferrer G, Pereira A, Moreno C, Montserrat E. Autoimmune cytopenia in chronic lymphocytic leukaemia: diagnosis and treatment. Br J Haematol 2011; 154(1): 14-22. [Medline]
Howlader N, Noone AM, Krapcho M, Garshell J, Miller D, Altekruse SF et al. SEER Cancer Statistics Review (CSR), 1975-2011. [seer.cancer.gov/csr/1975_2011/] National Cancer Institute, Bethesda, MD, based on November 2013 SEER data submission, posted to the SEER web site, April 2014.
IPI-145 shows promise in CLL patients. Cancer Discov 2014; 4(2): 136. [Medline]
Isidoro L, Pires P, Rito L, Cordeiro G. Progressive multifocal leukoencephalopathy in a patient with chronic lymphocytic leukaemia treated with alemtuzumab. BMJ Case Rep 2014; 2014. pii: bcr2013201781. [Medline]
Kater AP, Tonino SH, Egle A, Ramsay AG. How does lenalidomide target the chronic lymphocytic leukemia microenvironment? Blood 2014; 124(14): 2184-9. [Medline]
Kay NE, Geyer SM, Call TG, Shanafelt TD, Zent CS, Jelinek DF et al. Combination chemoimmunotherapy with pentostatin, cyclophosphamide, and rituximab shows significant clinical activity with low accompanying toxicity in previously untreated B chronic lymphocytic leukemia. Blood 2007; 109(2): 405-11. [Medline]
Keating MJ, O’Brien S, Albitar M, Lerner S, Plunkett W, Giles F et al. Early results of a chemoimmunotherapy regimen of fludarabine, cyclophosphamide, and rituximab as initial therapy for chronic lymphocytic leukemia. J Clin Oncol 2005; 23(18): 4079-88. [Medline]
Kennedy B, Rawstron A, Carter C, Ryan M, Speed K, Lucas G et al. Campath-1H and fludarabine in combination are highly active in refractory chronic lymphocytic leukemia. Blood 2002; 99(6): 2245-7. [Medline]
Knauf WU, Lissichkov T, Aldaoud A, Liberati A, Loscertales J, Herbrecht R et al. Phase III randomized study of bendamustine compared with chlorambucil in previously untreated patients with chronic lymphocytic leukemia. J Clin Oncol 2009; 27(26): 4378-84. [Medline]
Landau DA, Carter SL, Stojanov P, McKenna A, Stevenson K, Lawrence MS et al. Evolution and impact of subclonal mutations in chronic lymphocytic leukemia. Cell 2013; 152(4): 714-26. [Medline]
Lepretre S, Aurran T, Mahé B, Cazin B, Tournilhac O, Maisonneuve H et al. Excess mortality after treatment with fludarabine and cyclophosphamide in combination with alemtuzumab in previously untreated patients with chronic lymphocytic leukemia in a randomized phase 3 trial. Blood 2012; 119(22): 5104-10. [Medline]
Lin TS, Donohue KA, Byrd JC, Lucas MS, Hoke EE, Bengtson EM et al. Consolidation therapy with subcutaneous alemtuzumab after fludarabine and rituximab induction therapy for previously untreated chronic lymphocytic leukemia: final analysis of CALGB 10101. J Clin Oncol 2010; 28(29): 4500-6. [Medline]
Lopez C, Delgado J, Costa D, Conde L, Ghita G, Villamor N et al. Different distribution of NOTCH1 mutations in chronic lymphocytic leukemia with isolated trisomy 12 or associated with other chromosomal alterations. Genes Chromosomes Cancer 2012; 51(9): 881-9. [Medline]
Malavasi F, Deaglio S, Damle R, Cutrona G, Ferrarini M, Chiorazzi N. CD38 and chronic lymphocytic leukemia: a decade later. Blood 2011; 118(13): 3470-8. [Medline]
Mansouri L, Cahill N, Gunnarsson R, Smedby KE, Tjönnfjord E, Hjalgrim H et al. NOTCH1 and SF3B1 mutations can be added to the hierarchical prognostic classification in chronic lymphocytic leukemia. Leukemia 2013; 27(2): 512-4. [Medline]
Marcucci F, Mele A. Hepatitis viruses and non-Hodgkin lymphoma: epidemiology, mechanisms of tumorigenesis, and therapeutic opportunities. Blood 2011; 117(6): 1792-8. [Medline]
Matutes E, Polliack A. Morphological and immunophenotypic features of chronic lymphocytic leukemia. Rev Clin Exp Hematol 2000; 4(1): 22-47. [Medline]
Molica S, Reverter JC, Alberti A, Montserrat E. Timing of diagnosis and lymphocyte accumulation patterns in chronic lymphocytic leukemia: analysis of their clinical significance. Eur J Haematol 1990; 44(5): 277-81. [Medline]
Molica S, Mauro FR, Giannarelli D, Lauria F, Cortelezzi A, Brugiatelli M et al. Differentiating chronic lymphocytic leukemia from monoclonal B-lymphocytosis according to clinical outcome: on behalf of the GIMEMA chronic lymphoproliferative diseases working group. Haematologica 2011; 96(2): 277-83. [Medline]
Morrison VA. Infectious complications of chronic lymphocytic leukaemia: pathogenesis, spectrum of infection, preventive approaches. Best Pract Res Clin Haematol 2010; 23(1): 145-53. [Medline]
Byrd JC, O’Brien S, James DF. Ibrutinib in relapsed chronic lymphocytic leukemia. N Engl J Med 2013; 369(13): 1278-9. [Medline]
O’Brien S, Furman RR, Coutre SE, Sharman JP, Burger JA, Blum KA et al. Ibrutinib as initial therapy for elderly patients with chronic lymphocytic leukaemia or small lymphocytic lymphoma: an open-label, multicentre, phase 1b/2 trial. Lancet Oncol 2014; 15(1): 48-58. [Medline]
Pan JW, Cook LS, Schwartz SM, Weis NS. Incidence of leukemia in Asian migrants to the United States and their descendants. Cancer Causes Control 2002; 13(9): 791-5. [Medline]
Parikh SA, Keating MJ, O’Brien S, Wang X, Ferrajoli A, Faderl S et al. Frontline chemoimmunotherapy with fludarabine, cyclophosphamide, alemtuzumab, and rituximab for high-risk chronic lymphocytic leukemia. Blood 2011; 118(8): 2062-8. [Medline]
Pettitt AR, Matutes E, Oscier D. Alemtuzumab in combination with high-dose methylprednisolone is a logical, feasible and highly active therapeutic regimen in chronic lymphocytic leukaemia patients with p53 defects. Leukemia 2006; 20(8): 1441-5. [Medline]
Pettitt AR, Jackson R, Carruthers S, Dodd J, Dodd S, Oates M et al. Alemtuzumab in combination with methylprednisolone is a highly effective induction regimen for patients with chronic lymphocytic leukemia and deletion of TP53: final results of the national cancer research institute CLL206 trial. J Clin Oncol 2012; 30(14): 1647-55. [Medline]
Ponzoni M, Doglioni C, Caligaris-Cappio F. Chronic lymphocytic leukemia: the pathologist’s view of lymph node microenvironment. Semin Diagn Pathol 2011; 28: 161-6. [Medline]
Pospisilova S, Gonzalez D, Malcikova J, Trbusek M, Rossi D, Kater AP et al. ERIC recommendations on TP53 mutation analysis in chronic lymphocytic leukemia. Leukemia 2012; 26(7): 1458-61. [Medline]
Puente XS, Pinyol M, Quesada V, Conde L, Ordóñez GR, Villamor N et al. Whole-genome sequencing identifies recurrent mutations in chronic lymphocytic leukaemia. Nature 2011; 475(7354): 101-5. [Medline]
Quesada V, Conde L, Villamor N, Ordóñez GR, Jares P, Bassaganyas L et al. Exome sequencing identifies recurrent mutations of the splicing factor SF3B1 gene in chronic lymphocytic leukemia. Nat Genet 2011; 44(1): 47-52. [Medline]
Rai KR, Sawitsky A, Cronkite EP, Chanana AD, Levy RN, Pasternack BS. Clinical staging of chronic lymphocytic leukemia. Blood 1975; 46(2): 219-34. [Medline]
Rassenti LZ, Huynh L, Toy TL, Chen L, Keating MJ, Gribben JG et al. ZAP-70 compared with immunoglobulin heavy-chain gene mutation status as a predictor of disease progression in chronic lymphocytic leukemia. N Engl J Med 2004; 351(9): 893-901. [Medline]
Rossi D, Sozzi E, Puma A, De Paoli L, Rasi S, Spina V et al. The prognosis of clinical monoclonal B cell lymphocytosis differs from prognosis of Rai 0 chronic lymphocytic leukaemia and is recapitulated by biological risk factors. Br J Haematol 2009; 146(1): 64-75. [Medline]
Rossi D, Bruscaggin A, Spina V, Rasi S, Khiabanian H, Messina M et al. Mutations of the SF3B1 splicing factor in chronic lymphocytic leukemia: association with progression and fludarabine-refractoriness. Blood 2011; 118(26): 6904-8. [Medline]
Rossi D, Fangazio M, Rasi S, Vaisitti T, Monti S, Cresta S et al. Disruption of BIRC3 associates with fludarabine chemorefractoriness in TP53 wild-type chronic lymphocytic leukemia. Blood 2012a; 119(12): 2854-62. [Medline]
Rossi D, Fangazio M, Gaidano G. The spectrum of genetic defects in chronic lymphocytic leukemia. Mediterr J Hematol Infect Dis 2012b; 4(1): e2012076. [Medline]
Rossi D, Rasi S, Fabbri G, Spina V, Fangazio M, Forconi F et al. Mutations of NOTCH1 are an independent predictor of survival in chronic lymphocytic leukemia. Blood 2012c; 119(2): 521-9. [Medline]
Rossi D, Rasi S, Spina V, Fangazio M, Monti S, Greco M et al. Different impact of NOTCH1 and SF3B1 mutations on the risk of chronic lymphocytic leukemia transformation to Richter syndrome. Br J Haematol 2012d; 158(3): 426-9. [Medline]
Rossi D, Khiabanian H, Spina V, Ciardullo C, Bruscaggin A, Famà R et al. Clinical impact of small TP53 mutated subclones in chronic lymphocytic leukemia. Blood 2014; 123(14): 2139-47. [Medline]
Scarfò L, Zibellini S, Tedeschi A, Maura F, Neri A, Bertazzoni P et al. Impact of B-cell count and imaging screening in cMBL: any need to revise the current guidelines? Leukemia 2012; 26(7): 1703-7. [Medline]
Schetelig J, van Biezen A, Brand R, Caballero D, Martino R, Itala M et al. Allogeneic hematopoietic stem-cell transplantation for chronic lymphocytic leukemia with 17p deletion: a retrospective European Group for Blood and Marrow Transplantation analysis. J Clin Oncol 2008; 26(31): 5094-100. [Medline]
Schnaiter A1, Paschka P, Rossi M, Zenz T, Bühler A, Winkler D et al. NOTCH1, SF3B1, and TP53 mutations in fludarabine-refractory CLL patients treated with alemtuzumab: results from the CLL2H trial of the GCLLSG. Blood 2013; 122(7): 1266-70. [Medline]
Schuh A1, Becq J, Humphray S, Alexa A, Burns A, Clifford Ret al. Monitoring chronic lymphocytic leukemia progression by whole genome sequencing reveals heterogeneous clonal evolution patterns. Blood 2012; 120(20): 4191-6. [Medline]
Seymour JF, Davids MS, Pagel JM, Kahl BS, Wierda WG, Miller TP et al. Bcl-2 Inhibitor ABT-199 (GDC-0199) Monotherapy shows anti-tumor activity including complete remissions in high-risk relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). Blood 2013; 122(21) Suppl: abstract 872.
Shanafelt TD, Lin T, Geyer SM, Zent CS, Leung N, Kabat B et al. Pentostatin, cyclophosphamide, and rituximab regimen in older patients with chronic lymphocytic leukemia. Cancer 2007; 109: 2291-8. [Medline]
Shanafelt TD1, Kay NE, Rabe KG, Call TG, Zent CS, Maddocks Ket al. Brief report: natural history of individuals with clinically recognized monoclonal B-cell lymphocytosis compared with patients with Rai 0 chronic lymphocytic leukemia. J Clin Oncol 2009b; 27(24): 3959-63. [Medline]
Shanafelt TD, Ghia P, Lanasa MC, Landgren O, Rawstron AC. Monoclonal B-cell lymphocytosis (MBL): biology, natural history and clinical management. Leukemia 2010; 24(3): 512-20. [Medline]
Shanafelt TD, Kay NE, Rabe KG, Inwards DJ, Zent CS, Leis JF et al. Hematologist/oncologist disease-specific expertise and survival: lessons from chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Cancer 2012; 118(7): 1827-37. [Medline]
Slager SL, Caporaso NE, de Sanjose S, Goldin LR. Genetic susceptibility to chronic lymphocytic leukemia. Semin Hematol 2013; 50(4): 296-302. [Medline]
Slager SL, Benavente Y, Blair A, Vermeulen R, Cerhan JR, Costantini AS et al. Medical history, lifestyle, family history, and occupational risk factors for chronic lymphocytic leukemia/small lymphocytic lymphoma: the InterLymph Non-Hodgkin Lymphoma Subtypes Project. J Natl Cancer Inst Monogr 2014; 2014(48): 41-51. [Medline]
Stamatopoulos K, Belessi C, Moreno C, Boudjograh M, Guida G, Smilevska T et al. Over 20% of patients with chronic lymphocytic leukemia carry stereotyped receptors: Pathogenetic implications and clinical correlations. Blood 2007; 109(1): 259-70. [Medline]
Stankovic T, Weber P, Stewart G, Bedenham T, Murray J, Byrd PJ et al. Inactivation of ataxia telangiectasia mutated gene in B-cell chronic lymphocytic leukaemia. Lancet 1999; 353(9146): 26-9. [Medline]
Stilgenbauer S, Zenz T. Understanding and managing ultra high-risk chronic lymphocytic leukemia. Hematology Am Soc Hematol Educ Program 2010; 2010: 481-8. [Medline]
Stilgenbauer S, Schnaiter A, Paschka P, Zenz T, Rossi M, Döhner K et al. Gene mutations and treatment outcome in chronic lymphocytic leukemia: results from the CLL8 trial. Blood 2014; 123(21): 3247-54. [Medline]
Strati P, Caligaris-Cappio F. A matter of debate in chronic lymphocytic leukemia: is the occurrence of autoimmune disorders an indicator of chronic lymphocytic leukemia therapy? Curr Opin Oncol 2011; 23(5): 455-60. [Medline]
Strati P, Keating MJ, Wierda WG, Badoux XC, Calin S, Reuben JM et al. Lenalidomide induces long-lasting responses in elderly patients with chronic lymphocytic leukemia. Blood 2013; 122(5): 734-7. [Medline]
Strati P, Wierda W, Burger J, Ferrajoli A, Tam C, Lerner S et al. Myelosuppression after frontline fludarabine, cyclophosphamide, and rituximab in patients with chronic lymphocytic leukemia: analysis of persistent and new-onset cytopenia. Cancer 2013b; 119(21): 3805-11. [Medline]
Strati P, Keating MJ, O’Brien SM, Burger J, Ferrajoli A, Jain N et al. Eradication of bone marrow minimal residual disease may prompt early treatment discontinuation in CLL. Blood 2014; 123(24): 3727-32. [Medline]
Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H et al. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Lyon, IARC Press, 2008.
Tam CS1, O’Brien S, Wierda W, Kantarjian H, Wen S, Do KA et al. Long-term results of the fludarabine, cyclophosphamide, and rituximab regimen as initial therapy of chronic lymphocytic leukemia. Blood 2008; 112(4): 975-80. [Medline]
Vardi A, Agathangelidis A, Sutton LA, Ghia P, Rosenquist R, Stamatopoulos K. Immunogenetic studies of chronic lymphocytic leukemia: revelations and speculations about ontogeny and clinical evolution. Cancer research 2014; 74(16): 4211-6. [Medline]
Villamor N, Conde L, Martinez-Trillos A, Cazorla M, Navarro A, Beà S et al. NOTCH1 mutations identify a genetic subgroup of chronic lymphocytic leukemia patients with high risk of transformation and poor outcome. Leukemia 2013a; 27(5): 1100-6. [Medline]
Villamor N, Lopez-Guillermo A, Lopez-Otin C, Campo E. Next-generation sequencing in chronic lymphocytic leukemia. Semin Hematol 2013b; 50(4): 286-95. [Medline]
Wang L, Lawrence MS, Wan Y, Stojanov P, Sougnez C, Stevenson K et al. SF3B1 and other novel cancer genes in chronic lymphocytic leukemia. N Engl J Med 2011; 365(26): 2497-506. [Medline]
Wierda WG, Kipps TJ, Mayer J, Stilgenbauer S, Williams CD, Hellmann A et al. Ofatumumab as single-agent CD20 immunotherapy in fludarabine-refractory chronic lymphocytic leukemia. J Clin Oncol 2010; 28(10): 1749-55. [Medline]
Winkler D, Schneider C, Krober A, Pasqualucci L, Lichter P, Döhner H et al. Protein expression analysis of chromosome 12 candidate genes in chronic lymphocytic leukemia (CLL). Leukemia 2005; 19(7): 1211-5. [Medline]
Zenz T, Kröber A, Scherer K, Häbe S, Bühler A, Benner A et al. Monoallelic TP53 inactivation is associated with poor prognosis in chronic lymphocytic leukemia: results from a detailed genetic characterization with long-term follow-up. Blood 2008; 112(8): 3322-9. [Medline]
Zenz T, Häbe S, Denzel T, Mohr J, Winkler D, Bühler A et al. Detailed analysis of p53 pathway defects in fludarabine-refractory chronic lymphocytic leukemia (CLL): dissecting the contribution of 17p deletion, TP53 mutation, p53-p21 dysfunction, and miR34a in a prospective clinical trial. Blood 2009; 114(13): 2589-97. [Medline]
Zenz T, Vollmer D, Trbusek M, Smardova J, Benner A, Soussi T et al. TP53 mutation profile in chronic lymphocytic leukemia: evidence for a disease specific profile from a comprehensive analysis of 268 mutations. Leukemia 2010a; 24(12): 2072-9. [Medline]
Zenz T, Eichhorst B, Busch R, Denzel T, Häbe S, Winkler D et al. TP53 mutation and survival in chronic lymphocytic leukemia. J Clin Oncol 2010b; 28(29): 4473-9. [Medline]
Zent CS, Kay NE. Autoimmune complications in chronic lymphocytic leukaemia (CLL). Best Pract Res Clin Haematol 2010; 23(1): 47-59. [Medline]
Zhou Y, Tang G, Medeiros LJ, McDonnell TJ, Keating MJ, Wierda WG et al. Therapy-related myeloid neoplasms following fludarabine, cyclophosphamide, and rituximab (FCR) treatment in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma. Mod Pathol 2012; 25(2): 237-45. [Medline]
Dr. Andrés Ferreri (Associate Editor)
Department of Onco-Haematology, Division of Experimental Oncology, IRCCS San Raffaele Hospital (Milan, Italy)
Dr. Paolo Ghia (Author)
Department of Onco-Haematology, Division of Experimental Oncology, IRCCS San Raffaele Hospital, Milan (Italy) and University Vita-Salute San Raffaele, Milan, Italy
Dr. Lydia Scarfò (Author)
Department of Onco-Haematology, Division of Experimental Oncology, IRCCS San Raffaele Hospital, Milan (Italy) and University Vita-Salute San Raffaele, Milan, Italy