Higher-order connections between stereotyped subsets: implications for improved patient classification in CLL.

Chronic lymphocytic leukemia (CLL) is characterized by the existence of subsets of patients with (quasi)identical, stereotyped B-cell receptor (BcR) immunoglobulins. Patients in certain major stereotyped subsets often display remarkably consistent clinicobiological profiles, suggesting that the study of BcR immunoglobulin stereotypy in CLL has important implications for understanding disease pathophysiology and refining clinical decision-making. Nevertheless, several issues remain open, especially pertaining to the actual frequency of BcR immunoglobulin stereotypy and major subsets, as well as the existence of higher-order connections between individual subsets. To address these issues, we investigated clonotypic IGHV-IGHD-IGHJ gene rearrangements in a series of 29 856 patients with CLL, by far the largest series worldwide. We report that the stereotyped fraction of CLL peaks at 41% of the entire cohort and that all 19 previously identified major subsets retained their relative size and ranking, while 10 new ones emerged; overall, major stereotyped subsets had a cumulative frequency of 13.5%. Higher-level relationships were evident between subsets, particularly for major stereotyped subsets with unmutated IGHV genes (U-CLL), for which close relations with other subsets, termed "satellites," were identified. Satellite subsets accounted for 3% of the entire cohort. These results confirm our previous notion that major subsets can be robustly identified and are consistent in relative size, hence representing distinct disease variants amenable to compartmentalized research with the potential of overcoming the pronounced heterogeneity of CLL. Furthermore, the existence of satellite subsets reveals a novel aspect of repertoire restriction with implications for refined molecular classification of CLL.

Lenalidomide-bendamustine-rituximab in patients older than 65 years with untreated mantle cell lymphoma.

For elderly patients with mantle cell lymphoma (MCL), there is no defined standard therapy. In this multicenter, open-label phase 1/2 trial, we evaluated the addition of lenalidomide (LEN) to rituximab-bendamustine (R-B) as first-line treatment for elderly patients with MCL. Patients >65 years with untreated MCL, stages II-IV were eligible for inclusion. Primary end points were maximally tolerable dose (MTD) of LEN and progression-free survival (PFS). Patients received 6 cycles every four weeks of L-B-R (L D1-14, B 90 mg/m2 IV, days 1-2 and R 375 mg/m2 IV, day 1) followed by single LEN (days 1-21, every four weeks, cycles 7-13). Fifty-one patients (median age 71 years) were enrolled from 2009 to 2013. In phase 1, the MTD of LEN was defined as 10 mg in cycles 2 through 6, and omitted in cycle 1. After 6 cycles, the complete remission rate (CRR) was 64%, and 36% were MRD negative. At a median follow-up time of 31 months, median PFS was 42 months and 3-year overall survival was 73%. Infection was the most common nonhematologic grade 3 to 5 event and occurred in 21 (42%) patients. Opportunistic infections occurred in 3 patients: 2 Pneumocystis carinii pneumonia and 1 cytomegalovirus retinitis. Second primary malignancies (SPM) were observed in 8 patients (16%). LEN could safely be combined with R-B when added from the second cycle in patients with MCL, and was associated with a high rate of CR and molecular remission. However, we observed a high degree of severe infections and an unexpected high number of SPMs, which may limit its use. This trial is registered at www.Clinicaltrials.gov as #NCT00963534.

Molecular Monitoring after Autologous Stem Cell Transplantation and Preemptive Rituximab Treatment of Molecular Relapse; Results from the Nordic Mantle Cell Lymphoma Studies (MCL2 and MCL3) with Median Follow-Up of 8.5 Years.

The main objectives of the present study were to monitor minimal residual disease (MRD) in the bone marrow of patients with mantle cell lymphoma (MCL) to predict clinical relapse and guide preemptive treatment with rituximab. Among the patients enrolled in 2 prospective trials by the Nordic Lymphoma Group, 183 who had completed autologous stem cell transplantation (ASCT) and in whom an MRD marker had been obtained were included in our analysis. Fresh samples of bone marrow were analyzed for MRD by a combined standard nested and quantitative real-time PCR assay for Bcl-1/immunoglobulin heavy chain gene (IgH) and clonal IgH rearrangements. Significantly shorter progression-free survival (PFS) and overall survival (OS) was demonstrated for patients who were MRD positive pre-ASCT (54 patients) or in the first analysis post-ASCT (23 patients). The median PFS was only 20 months in those who were MRD-positive in the first sample post-ASCT, compared with 142 months in the MRD-negative group (P < .0001). OS was 75% at 10 years and median not reached in the MRD-negative group, compared with only 35 months in the MRD-positive group (P < .0001). Of the 86 patients (47%) who remained in continuous molecular remission, 73% were still in clinical remission after 10 years. For all patients, the median time from ASCT to first molecular relapse was 55 months, with a continuous occurrence of late molecular relapses. Fifty-eight patients who experienced MRD relapse received rituximab as preemptive treatment on 1 or more occasions, and in this group, the median time from first molecular relapse to clinical relapse was 55 months. In most cases, rituximab converted patients to MRD negativity (87%), but many patients became MRD-positive again later during follow-up (69%). By multivariate analysis, high-risk Mantle Cell Lymphoma International Prognostic Index score and positive MRD status pre-ASCT predicted early molecular relapse. In conclusion, preemptive rituximab treatment converts patients to MRD negativity and likely postpones clinical relapse. Molecular monitoring offers an opportunity to select some patients for therapeutic intervention and to avoid unnecessary treatment in others. MRD-positive patients in the first analysis post-ASCT have a dismal prognosis and thus are in need of novel strategies.

Not all IGHV3-21 chronic lymphocytic leukemias are equal: prognostic considerations.

An unresolved issue in chronic lymphocytic leukemia (CLL) is whether IGHV3-21 gene usage, in general, or the expression of stereotyped B-cell receptor immunoglobulin defining subset #2 (IGHV3-21/IGLV3-21), in particular, determines outcome for IGHV3-21-utilizing cases. We reappraised this issue in 8593 CLL patients of whom 437 (5%) used the IGHV3-21 gene with 254/437 (58%) classified as subset #2. Within subset #2, immunoglobulin heavy variable (IGHV)-mutated cases predominated, whereas non-subset #2/IGHV3-21 was enriched for IGHV-unmutated cases (P = .002). Subset #2 exhibited significantly shorter time-to-first-treatment (TTFT) compared with non-subset #2/IGHV3-21 (22 vs 60 months, P = .001). No such difference was observed between non-subset #2/IGHV3-21 vs the remaining CLL with similar IGHV mutational status. In conclusion, IGHV3-21 CLL should not be axiomatically considered a homogeneous entity with adverse prognosis, given that only subset #2 emerges as uniformly aggressive, contrasting non-subset #2/IGVH3-21 patients whose prognosis depends on IGHV mutational status as the remaining CLL.

Nordic MCL3 study: 90Y-ibritumomab-tiuxetan added to BEAM/C in non-CR patients before transplant in mantle cell lymphoma.

The main objective of the MCL3 study was to improve outcome for patients not in complete remission (CR) before transplant by adding (90)Y-ibritumomab-tiuxetan (Zevalin) to the high-dose regimen. One hundred sixty untreated, stage II-IV mantle cell lymphoma patients <66 years received rituximab (R)-maxi-CHOP (cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone) alternating with R-high-dose cytarabine (6 cycles total), followed by high-dose BEAM/C (bis-chloroethylnitrosourea, etoposide, cytarabine, and melphalan or cyclophosphamide) and autologous stem cell transplantation from 2005 to 2009. Zevalin (0.4 mCi/kg) was given to responders not in CR before transplant. Overall response rate pretransplant was 97%. The outcome did not differ from that of the historic control: the MCL2 trial with similar treatment except for Zevalin. Overall survival (OS), event-free survival (EFS), and progression-free survival (PFS) at 4 years were 78%, 62%, and 71%, respectively. For responding non-CR patients who received Zevalin, duration of response was shorter than for the CR group. Inferior PFS, EFS, and OS were predicted by positron emission tomography (PET) positivity pretransplant and detectable minimal residual disease (MRD) after transplant. In conclusion, positive PET and MRD were strong predictors of outcome. Intensification with Zevalin may be too late to improve the outcome of patients not in CR before transplant. This trial was registered at www.clinicaltrials.gov as #NCT00514475.

Different spectra of recurrent gene mutations in subsets of chronic lymphocytic leukemia harboring stereotyped B-cell receptors.

We report on markedly different frequencies of genetic lesions within subsets of chronic lymphocytic leukemia patients carrying mutated or unmutated stereotyped B-cell receptor immunoglobulins in the largest cohort (n=565) studied for this purpose. By combining data on recurrent gene mutations (BIRC3, MYD88, NOTCH1, SF3B1 and TP53) and cytogenetic aberrations, we reveal a subset-biased acquisition of gene mutations. More specifically, the frequency of NOTCH1 mutations was found to be enriched in subsets expressing unmutated immunoglobulin genes, i.e. #1, #6, #8 and #59 (22-34%), often in association with trisomy 12, and was significantly different (P<0.001) to the frequency observed in subset #2 (4%, aggressive disease, variable somatic hypermutation status) and subset #4 (1%, indolent disease, mutated immunoglobulin genes). Interestingly, subsets harboring a high frequency of NOTCH1 mutations were found to carry few (if any) SF3B1 mutations. This starkly contrasts with subsets #2 and #3 where, despite their immunogenetic differences, SF3B1 mutations occurred in 45% and 46% of cases, respectively. In addition, mutations within TP53, whilst enriched in subset #1 (16%), were rare in subsets #2 and #8 (both 2%), despite all being clinically aggressive. All subsets were negative for MYD88 mutations, whereas BIRC3 mutations were infrequent. Collectively, this striking bias and skewed distribution of mutations and cytogenetic aberrations within specific chronic lymphocytic leukemia subsets implies that the mechanisms underlying clinical aggressiveness are not uniform, but rather support the existence of distinct genetic pathways of clonal evolution governed by a particular stereotyped B-cell receptor selecting a certain molecular lesion(s).

Stereotyped B-cell receptors in one-third of chronic lymphocytic leukemia: a molecular classification with implications for targeted therapies.

Mounting evidence indicates that grouping of chronic lymphocytic leukemia (CLL) into distinct subsets with stereotyped BCRs is functionally and prognostically relevant. However, several issues need revisiting, including the criteria for identification of BCR stereotypy and its actual frequency as well as the identification of "CLL-biased" features in BCR Ig stereotypes. To this end, we examined 7596 Ig VH (IGHV-IGHD-IGHJ) sequences from 7424 CLL patients, 3 times the size of the largest published series, with an updated version of our purpose-built clustering algorithm. We document that CLL may be subdivided into 2 distinct categories: one with stereotyped and the other with nonstereotyped BCRs, at an approximate ratio of 1:2, and provide evidence suggesting a different ontogeny for these 2 categories. We also show that subset-defining sequence patterns in CLL differ from those underlying BCR stereotypy in other B-cell malignancies. Notably, 19 major subsets contained from 20 to 213 sequences each, collectively accounting for 943 sequences or one-eighth of the cohort. Hence, this compartmentalized examination of VH sequences may pave the way toward a molecular classification of CLL with implications for targeted therapeutic interventions, applicable to a significant number of patients assigned to the same subset.

Silenced B-cell receptor response to autoantigen in a poor-prognostic subset of chronic lymphocytic leukemia.

Chronic lymphocytic leukemia B cells express auto/xeno antigen-reactive antibodies that bind to self-epitopes and resemble natural IgM antibodies in their repertoire. One of the antigenic structures recognized is oxidation-induced malonedialdehyde that is present on low-density lipoprotein, apoptotic blebs, and on certain microbes. The poor-prognostic stereotyped subset #1 (Clan I IGHV genes-IGKV1(D)-39) express IgM B-cell receptors that bind oxidized low-density lipoprotein. In this study, we have used for the first time this authentic cognate antigen for analysis of downstream B-cell receptor-signal transduction events, since it is more faithful to B-cell physiology than anti-IgM. Multivalent oxidized low-density lipoprotein showed specific binding to subset #1 IgM/IgD B-cell receptors, whereas native low-density lipoprotein did not. The antigen binding induced prompt receptor clustering followed by internalization. However, the receptor-signal transduction was silenced, revealing no Ca(2+) mobilization or cell-cycle entry, while phosphorylated extracellular-regulated kinase 1/2 basal levels were high and could not be elevated further by oxidized low-density lipoprotein. Interestingly, B-cell receptor responsiveness was recovered after 48-h culture in the absence of antigen in half of the cases. Toll-like receptor 9-ligand was found to breach the B-cell receptor-signaling incompetence in 5 of 12 cases pointing to intra-subset heterogeneity. Altogether, this study supports B-cell receptor unresponsiveness to cognate self-antigen on its own in poor-prognostic subset #1 chronic lymphocytic leukemia, indicating that these cells proliferate by other mechanisms that may override B-cell receptor silencing brought about in a context of self-tolerance/anergy. These novel findings have implications for the understanding of chronic lymphocytic leukemia pathobiology and therapy.

MRD-driven treatment with venetoclax-R2 in mantle cell lymphoma: the Nordic Lymphoma Group MCL7 VALERIA trial.

ABSTRACT: Despite improvements in treatment of mantle cell lymphoma (MCL), most patients eventually relapse. In this multicenter phase 1b/2 trial, we evaluated safety and efficacy of minimal residual disease (MRD)-driven venetoclax, lenalidomide, and rituximab (venetoclax-R2) in relapsed/refractory (R/R) MCL and explored the feasibility of stopping treatment in molecular remission. The primary end point was overall response rate (ORR) at 6 months. After dose escalation, the recommended phase 2 dose was lenalidomide 20 mg daily, days 1 to 21; venetoclax 600 mg daily after ramp-up; and rituximab 375 mg/m2 weekly for 4 weeks, then every 8 weeks. MRD monitoring by RQ-PCR was performed every 3 months. When MRD-negativity in the blood was reached, treatment was continued for another 3 months; if MRD-negativity was then confirmed, treatment was stopped. In total, 59 patients were enrolled, with a median age of 73 years. At 6 months, the ORR was 63% (29 complete remission [CR], 8 partial remission [PR]), and 40% (4 CR, 2 PR) for patients previously failing a Bruton tyrosine kinase (BTK) inhibitor. Median progression-free survival (PFS) was 21 months, with median overall survival of 31 months. TP53 mutation was associated with inferior PFS (P < .01). Overall, 28 patients (48%) discontinued treatment in molecular remission, and 25 remain MRD negative after a median of 17.4 months. Hematological toxicity was frequent, with 52 of 59 (88%) patients with G3-4 neutropenia and 21 of 59 (36%) patients with G3-4 thrombocytopenia. To conclude, MRD-driven venetoclax-R2 is feasible and tolerable and shows efficacy in R/R MCL, also after BTK inhibitor failure. This trial was registered at www.ClinicalTrials.gov as #NCT03505944.

Is there a role for antigen selection in mantle cell lymphoma? Immunogenetic support from a series of 807 cases.

We examined 807 productive IGHV-IGHD-IGHJ gene rearrangements from mantle cell lymphoma (MCL) cases, by far the largest series to date. The IGHV gene repertoire was remarkably biased, with IGHV3-21, IGHV4-34, IGHV1-8, and IGHV3-23 accounting for 46.3% of the cohort. Eighty-four of 807 (10.4%) cases, mainly using the IGHV3-21 and IGHV4-34 genes, were found to bear stereotyped heavy complementarity-determining region 3 (VH CDR3) sequences and were placed in 38 clusters. Notably, the MCL stereotypes were distinct from those reported for chronic lymphocytic leukemia. Based on somatic hypermutation (SHM) status, 238/807 sequences (29.5%) carried IGHV genes with 100% germ line identity; the remainder (569/807; 70.5%) exhibited different SHM impact, ranging from minimal (in most cases) to pronounced. Shared replacement mutations across the IGHV gene were identified for certain subgroups, especially those using IGHV3-21, IGHV1-8, and IGHV3-23. Comparison with other entities, in particular CLL, revealed that several of these mutations were "MCL-biased." In conclusion, MCL is characterized by a highly restricted immunoglobulin gene repertoire with stereotyped VH CDR3s and very precise SHM targeting, strongly implying a role for antigen-driven selection of the clonogenic progenitors. Hence, an antigen-driven origin of MCL could be envisaged, at least for subsets of cases.

Anti-PD-L1/PD-L2 therapeutic vaccination in untreated chronic lymphocytic leukemia patients with unmutated IgHV.

Chronic lymphocytic leukemia (CLL) patients with unmutated immunoglobulin heavy chain (IgHV) are at risk of early disease progression compared to patients with mutated IgHV. As a preventive strategy, we treated 19 previously untreated CLL patients with unmutated IgHV in a phase 1/2 trial (clinicaltrials.gov, NCT03939234) exploring the efficacy and toxicity of a therapeutic cancer vaccine containing peptides derived from programmed death ligand 1 (PD-L1) and ligand 2 (PD-L2), hoping to restore immunological control of the disease. According to the International Workshop on Chronic lymphocytic Leukemia (iwCLL) response criteria, no patients obtained a response; however, during follow-up, one patient had complete normalization of the peripheral lymphocyte count and remained in biochemical remission after a follow-up time of 15 months. At the end of treatment, one patient had progressed, and 17 patients had stable disease. During follow-up with a median time of 23.5 months since inclusion, seven patients had progressed, and eight patients had stable disease. The median time to first treatment (TTFT) from diagnosis was 90.3 months with a median follow-up time of 50.1 months. This apparent favorable outcome in TTFT needs to be investigated in a randomized setting, as our population may have been biased. More than 80% of patients obtained vaccine-specific immune responses, confirming the immunogenicity of the vaccine. The vaccine was generally well tolerated with only grade I-II adverse events. Although there were some signs of clinical effects, the vaccine seems to be insufficient as monotherapy in CLL, possibly due to a high tumor burden. The efficacy of the vaccine should preferably be tested in combination with novel targeted therapies or as a consolidating treatment.

Detailed Long-Term Follow-Up of Patients Who Relapsed After the Nordic Mantle Cell Lymphoma Trials: MCL2 and MCL3.

Mantle cell lymphoma (MCL) is an incurable disease with a highly variable clinical course. The prognosis after relapse is generally poor, and no standard of care exists. We investigated the postrelapse outcomes of 149 patients who were initially treated in the Nordic Lymphoma Group trials, MCL2 or MCL3, both representing intensive cytarabine-containing frontline regimens including autologous stem cell transplant. Patients with progression of disease before 24 months (POD24, n = 51, 34%) displayed a median overall survival of 6.6 months compared with 46 months for patients with later POD (n = 98, 66%; P < 0.001). MCL international prognostic index, cell proliferation marker, blastoid morphology, and TP53 mutations showed independent prognostic value irrespective of POD24, and in a combined, exploratory risk score, patients with 0, 1, 2-3, or 4-5 high-risk markers, respectively, displayed a 5-year overall survival of 62%, 39%, 31%, and 0%. By a comparison of median progression-free survival of the different salvage therapies in the relapse setting, bendamustine-rituximab was superior to all other combination chemotherapy regimens; however, it was also associated with longer responses to last line of therapy. Collectively, we confirm the prognostic impact of POD24 and highlight the relevance of other biomarkers, and we emphasize the importance of novel therapies for patients with high-risk features at first POD.

An immunogenic first-in-human immune modulatory vaccine with PD-L1 and PD-L2 peptides is feasible and shows early signs of efficacy in follicular lymphoma.

Cells in the tumor microenvironment of Follicular lymphoma (FL) express checkpoint molecules such as programmed death ligands 1 and 2 (PD-L1 and PD-L2) and are suppressing anti-tumor immune activity. Stimulation of peripheral blood mononuclear cells (PBMC) with PD-L1 (IO103) or PD-L2 (IO120) peptides can activate specific T cells inducing anti-regulatory functions including cytotoxicity against PD-L1/PD-L2-expressing cells. In this study, we vaccinated eight FL patients with PD-L1 and PD-L2 peptides following treatment with standard chemotherapy. Patients experienced grade 1-2 injection site reaction (5/8) and mild flu-like symptoms (6/8). One patient experienced neutropenia and thrombocytopenia during pseudo-progression. Enzyme-linked immunospot detected vaccine-specific immune responses in PBMC from all patients, predominately toward PD-L1. The circulating immune composition was stable during treatment; however, we observed a reduction regulatory T cells, however, not significant. One patient achieved a complete remission during vaccination and two patients had pseudo-progression followed by long-term disease regression. Further examination of these early signs of clinical efficacy of the dual-epitope vaccine in a larger study is warranted.

The Number of Signaling Pathways Altered by Driver Mutations in Chronic Lymphocytic Leukemia Impacts Disease Outcome.

PURPOSE: Investigation of signaling pathways altered by recurrent gene mutations and their clinical impact in a consecutive cohort of patients with newly diagnosed chronic lymphocytic leukemia (CLL). The heterogeneous clinical course and genetic complexity of CLL warrant improved molecular prognostication. However, the prognostic value of recurrent mutations at the time of diagnosis remains unclear. EXPERIMENTAL DESIGN: We sequenced samples from 314 consecutive, newly diagnosed patients with CLL to investigate the clinical impact of 56 recurrently mutated genes assessed by next-generation sequencing. RESULTS: Mutations were identified in 70% of patients with enrichment among IGHV unmutated cases. With 6.5 years of follow-up, 15 mutated genes investigated at the time of diagnosis demonstrated significant impact on time to first treatment (TTFT). Carrying driver mutations was associated with shorter TTFT and poor overall survival. For outcome from CLL diagnosis, the number of signaling pathways altered by driver mutations stratified patients better than the number of driver mutations. Moreover, we demonstrated gradual impact on TTFT with increasing number of altered pathways independent of CLL-IPI risk. Thus, a 25-gene, pathway-based biomarker assessing recurrent mutations refines prognostication in CLL, in particular for CLL-IPI low- and intermediate-risk patients. External validation emphasized that a broad gene panel including low burden mutations was key for the biomarker based on altered pathways. CONCLUSIONS: We propose to include the number of pathways altered by driver mutations as a biomarker together with CLL-IPI in prospective studies of CLL from time of diagnosis for incorporation into clinical care and personalized follow-up and treatment.

Ibrutinib, lenalidomide, and rituximab in relapsed or refractory mantle cell lymphoma (PHILEMON): a multicentre, open-label, single-arm, phase 2 trial.

BACKGROUND: Regimens based on ibrutinib alone and lenalidomide and rituximab in combination show high activity in patients with relapsed or refractory mantle cell lymphoma. We hypothesised that the combination of all three drugs would improve efficacy compared with previously published data on either regimen alone. METHODS: In this multicentre, open-label, single-arm, phase 2 trial, we enrolled patients aged 18 years or older with relapsed or refractory mantle cell lymphoma who had previously been treated with at least one rituximab-containing regimen, an Eastern Cooperative Oncology Group performance status score of 0-3, and at least one site of measurable disease, and who met criteria for several laboratory-assessed parameters. Treatment was divided into an induction phase of 12 cycles of 28 days with all three drugs and a maintenance phase with ibrutinib and rituximab only (cycle duration 56 days), given until disease progression or unacceptable toxicity. In the induction phase, patients received intravenous (375 mg/m2) or subcutaneous (1400 mg) rituximab once a week during cycle 1 and then once every 8 weeks. Oral ibrutinib (560 mg once a day) was given to patients every day in the cycle, whereas oral lenalidomide (15 mg once a day) was given on days 1-21. The primary endpoint was overall response assessed in the intention-to-treat population according to Lugano criteria. Safety analysis included all patients who received the treatment, irrespective of eligibility or duration of treatment. The trial is ongoing, but is no longer accruing patients, and is registered with ClinicalTrials.gov, number NCT02460276. FINDINGS: Between April 30, 2015, and June 1, 2016, we enrolled 50 patients with relapsed or refractory mantle cell lymphoma at ten centres in Sweden, Finland, Norway, and Denmark. At a median follow-up of 17·8 months (IQR 14·7-20·9), 38 (76%, 95% CI 63-86) patients had an overall response, including 28 (56%, 42-69) patients who had a complete response and ten (20%, 11-33) who had a partial response. The most common grade 3-4 adverse events were neutropenia (in 19 [38%] of 50 patients), infections (in 11 [22%] patients), and cutaneous toxicity (in seven [14%] patients). There were three treatment-related deaths during the study, two due to sepsis and one due to embolic stroke. INTERPRETATION: Our results provide preliminary evidence that the triplet combination of ibrutinib, lenalidomide, and rituximab is an active regimen in patients with relapsed or refractory mantle cell lymphoma, and should be evaluated in a prospective randomised controlled trial. FUNDING: Janssen and Celgene.

Chronic Lymphocytic Leukemia with Mutated IGHV4-34 Receptors: Shared and Distinct Immunogenetic Features and Clinical Outcomes.

Purpose: We sought to investigate whether B cell receptor immunoglobulin (BcR IG) stereotypy is associated with particular clinicobiological features among chronic lymphocytic leukemia (CLL) patients expressing mutated BcR IG (M-CLL) encoded by the IGHV4-34 gene, and also ascertain whether these associations could refine prognostication.Experimental Design: In a series of 19,907 CLL cases with available immunogenetic information, we identified 339 IGHV4-34-expressing cases assigned to one of the four largest stereotyped M-CLL subsets, namely subsets #4, #16, #29 and #201, and investigated in detail their clinicobiological characteristics and disease outcomes.Results: We identified shared and subset-specific patterns of somatic hypermutation (SHM) among patients assigned to these subsets. The greatest similarity was observed between subsets #4 and #16, both including IgG-switched cases (IgG-CLL). In contrast, the least similarity was detected between subsets #16 and #201, the latter concerning IgM/D-expressing CLL. Significant differences between subsets also involved disease stage at diagnosis and the presence of specific genomic aberrations. IgG subsets #4 and #16 emerged as particularly indolent with a significantly (P < 0.05) longer time-to-first-treatment (TTFT; median TTFT: not yet reached) compared with the IgM/D subsets #29 and #201 (median TTFT: 11 and 12 years, respectively).Conclusions: Our findings support the notion that BcR IG stereotypy further refines prognostication in CLL, superseding the immunogenetic distinction based solely on SHM load. In addition, the observed distinct genetic aberration landscapes and clinical heterogeneity suggest that not all M-CLL cases are equal, prompting further research into the underlying biological background with the ultimate aim of tailored patient management. Clin Cancer Res; 23(17); 5292-301. ©2017 AACR.

Clinical effect of stereotyped B-cell receptor immunoglobulins in chronic lymphocytic leukaemia: a retrospective multicentre study.

BACKGROUND: About 30% of cases of chronic lymphocytic leukaemia (CLL) carry quasi-identical B-cell receptor immunoglobulins and can be assigned to distinct stereotyped subsets. Although preliminary evidence suggests that B-cell receptor immunoglobulin stereotypy is relevant from a clinical viewpoint, this aspect has never been explored in a systematic manner or in a cohort of adequate size that would enable clinical conclusions to be drawn. METHODS: For this retrospective, multicentre study, we analysed 8593 patients with CLL for whom immunogenetic data were available. These patients were followed up in 15 academic institutions throughout Europe (in Czech Republic, Denmark, France, Greece, Italy, Netherlands, Sweden, and the UK) and the USA, and data were collected between June 1, 2012, and June 7, 2013. We retrospectively assessed the clinical implications of CLL B-cell receptor immunoglobulin stereotypy, with a particular focus on 14 major stereotyped subsets comprising cases expressing unmutated (U-CLL) or mutated (M-CLL) immunoglobulin heavy chain variable genes. The primary outcome of our analysis was time to first treatment, defined as the time between diagnosis and date of first treatment. FINDINGS: 2878 patients were assigned to a stereotyped subset, of which 1122 patients belonged to one of 14 major subsets. Stereotyped subsets showed significant differences in terms of age, sex, disease burden at diagnosis, CD38 expression, and cytogenetic aberrations of prognostic significance. Patients within a specific subset generally followed the same clinical course, whereas patients in different stereotyped subsets-despite having the same immunoglobulin heavy variable gene and displaying similar immunoglobulin mutational status-showed substantially different times to first treatment. By integrating B-cell receptor immunoglobulin stereotypy (for subsets 1, 2, and 4) into the well established Döhner cytogenetic prognostic model, we showed these, which collectively account for around 7% of all cases of CLL and represent both U-CLL and M-CLL, constituted separate clinical entities, ranging from very indolent (subset 4) to aggressive disease (subsets 1 and 2). INTERPRETATION: The molecular classification of chronic lymphocytic leukaemia based on B-cell receptor immunoglobulin stereotypy improves the Döhner hierarchical model and refines prognostication beyond immunoglobulin mutational status, with potential implications for clinical decision making, especially within prospective clinical trials. FUNDING: European Union; General Secretariat for Research and Technology of Greece; AIRC; Italian Ministry of Health; AIRC Regional Project with Fondazione CARIPARO and CARIVERONA; Regione Veneto on Chronic Lymphocytic Leukemia; Nordic Cancer Union; Swedish Cancer Society; Swedish Research Council; and National Cancer Institute (NIH).