Prolymphocytic Leukaemia: an Update on Biology and Treatment

PURPOSE OF REVIEW

This review summarises the recent advances in knowledge regarding the biology and treatment of prolymphocytic leukaemias.

RECENT FINDINGS

Both B-PLL and T-PLL are genetically complex, and the molecular landscape of these diseases has been well characterised recently. Diagnostic criteria for T-PLL have been refined with the publication of the first international consensus criteria, whereas the diagnosis of B-PLL has been thrown into question by the most recent WHO classification. Treatment advances in B-PLL have relied heavily on the advances seen in CLL that have then been extrapolated to B-PLL with just a few case reports to support the use of these targeted inhibitors. Despite increased knowledge of the biology of T-PLL and some elegant pre-clinical models to identify potential treatments, unfortunately, no improvements have been made in the treatment of T-PLL. Unmet need is a term oft used for many diseases, but this is particularly true for patients with prolymphocytic leukaemias. Ongoing improvements in our understanding of these diseases will hopefully lead to improved therapies in the future.

Many People With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma Benefit From Ibrutinib Treatment Up To 8 Years: A Plain Language Summary

WHAT IS THIS SUMMARY ABOUT?

This is a plain language summary of a publication describing long-term results from the RESONATE-2 study with up to 8 years of follow-up. The original paper was published in Blood Advances in June 2022.

WHAT WERE THE RESULTS?

Researchers looked at 269 adults with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) who had not received any treatment for their CLL/SLL. Study participants were randomly divided into two groups: 136 participants received treatment with a drug called ibrutinib, and 133 participants received treatment with a drug called chlorambucil. Participants in the study were treated and followed for up to 8 years, with results showing that more participants who took ibrutinib (59%) were alive without worsening of their disease at 7 years after starting treatment than participants who took chlorambucil (9%). Almost half of the participants (42%) were able to stay on ibrutinib treatment for up to 8 years.

WHAT DO THE RESULTS OF THE STUDY MEAN?

In people with CLL or SLL, more participants who were taking ibrutinib were alive without worsening of their disease after 7 years compared with participants who took chlorambucil. Clinical Trial Registration: NCT01722487 (ClinicalTrials.gov) Clinical Trial Registration: NCT01724346 (ClinicalTrials.gov).

Consensus opinion from an international group of experts on measurable residual disease in hairy cell leukemia

A significant body of literature has been generated related to the detection of measurable residual disease (MRD) at the time of achieving complete remission (CR) in patients with hairy cell leukemia (HCL). However, due to the indolent nature of the disease as well as reports suggesting long-term survival in patients treated with a single course of a nucleoside analog albeit without evidence of cure, the merits of detection of MRD and attempts to eradicate it have been debated. Studies utilizing novel strategies in the relapse setting have demonstrated the utility of achieving CR with undetectable MRD (uMRD) in prolonging the duration of remission. Several assays including immunohistochemical analysis of bone marrow specimens, multi-parameter flow cytometry and molecular assays to detect the mutant BRAF V600E gene or the consensus primer for the immunoglobulin heavy chain gene (IGH) rearrangement have been utilized with few comparative studies. Here we provide a consensus report on the available data, the potential merits of MRD assessment in the front-line and relapse settings and recommendations on future role of MRD assessment in HCL.

Development of a distributed international patient data registry for hairy cell leukemia

Hairy cell leukemia (HCL) is a rare lymphoproliferative disorder, comprising only 2% of all leukemias. The Hairy Cell Leukemia Foundation (HCLF) has developed a patient data registry to enable investigators to better study the clinical features, treatment outcomes, and complications of patients with HCL. This system utilizes a centralized registry architecture. Patients are enrolled at HCL Centers of Excellence (COE) or via a web-based portal. All data are de-identified, which reduces regulatory burden and increases opportunities for data access and re-use. To date, 579 patients have been enrolled in the registry. Efforts are underway to engage additional COE's to expand access to patients across the globe. This international PDR will enable researchers to study outcomes in HCL in ways not previously possible due to the rarity of the disease and will serve as a platform for future prospective research.

Patient-driven research: Initial results from a prospective health-related quality of life study performed at the request of patients living with hairy cell leukemia

A diagnosis of leukemia can have a profound effect on patients' health-related quality of life (HRQoL), however this has not been measured prospectively in patients with hairy cell leukemia (HCL). At the request of patients living with HCL who had identified this gap in knowledge about the disease, we conducted a longitudinal study of HRQoL among patients enrolled in the HCL Patient Data Registry (PDR). From September 1, 2018 to September 1, 2020, 165 patients were enrolled in the study and completed the baseline survey. The Functional Assessment of Cancer Therapy - Leukemia (FACT-Leu) was used to measure patients' HRQoL. Results show that newly diagnosed HCL patients reported the lowest HRQoL, followed by patients in relapse and those on "watch and wait." Factors associated with higher (better) FACT-Leu total scores in the multivariable analysis included older age, higher social support, and greater physical activity. These same factors were associated with lower levels of fatigue. In rare diseases where it is difficult to perform large prospective studies, patient/researcher collaborations are critical for the identification of studies that are of importance to patients and their families in order to maximize the benefits of the research and improve the lives of patients living with HCL.

Mature T-Cell leukemias: Challenges in Diagnosis

T-cell clones can frequently be identified in peripheral blood. It can be difficult to appreciate whether these are benign and transient or whether they signify a clonal disorder. We review factors that aid in understanding the relevance of T-cell clones. Conversely, obvious pathological T-cell clones can be detected in blood, but there is uncertainty in how to categorize this clonal T cell population, thus, we adopt a multidisciplinary review of the clinical features, diagnostic material and radiology before making the diagnosis. In this review we shall discuss some of these challenges faced when diagnosing mature T-cell leukemias.

Chronic lymphocytic leukaemia and Richter's transformation: multimodal review and new imaging paradigms

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in adults. It is a malignancy of CD5 B-cells characterised by small, mature-appearing lymphocytes accumulating in the blood, bone marrow, and lymphoid tissues. Richer transformation (RT) is an important adverse complication. Detection of RT is critical to allow initiation of appropriate therapy. CLL staging and response evaluation is complicated and nuanced. From our extensive tertiary centre experience of several hundred CLL cases over the last decade, we detail key computed tomography (CT) and positron-emission tomography (PET) imaging features of the natural history of CLL. The authors present an original imaging-based patient-management paradigm for the investigation of potential RT, which will inform global practice. Potential applications of whole-body diffusion weighted imaging, novel PET radiotracers, minimal residual disease, and ct-DNA are addressed.

Moxetumomab pasudotox in heavily pre-treated patients with relapsed/refractory hairy cell leukemia (HCL): long-term follow-up from the pivotal trial

Background

Moxetumomab pasudotox is a recombinant CD22-targeting immunotoxin. Here, we present the long-term follow-up analysis of the pivotal, multicenter, open-label trial (NCT01829711) of moxetumomab pasudotox in patients with relapsed/refractory (R/R) hairy cell leukemia (HCL).

Methods

Eligible patients had received ≥ 2 prior systemic therapies, including ≥ 2 purine nucleoside analogs (PNAs), or ≥ 1 PNA followed by rituximab or a BRAF inhibitor. Patients received 40 µg/kg moxetumomab pasudotox intravenously on Days 1, 3, and 5 of each 28-day cycle for up to six cycles. Disease response and minimal residual disease (MRD) status were determined by blinded independent central review. The primary endpoint was durable complete response (CR), defined as achieving CR with hematologic remission (HR, blood counts for CR) lasting > 180 days.

Results

Eighty adult patients were treated with moxetumomab pasudotox and 63% completed six cycles. Patients had received a median of three lines of prior systemic therapy; 49% were PNA-refractory, and 38% were unfit for PNA retreatment. At a median follow-up of 24.6 months, the durable CR rate (CR with HR > 180 days) was 36% (29 patients; 95% confidence interval: 26–48%); CR with HR ≥ 360 days was 33%, and overall CR was 41%. Twenty-seven complete responders (82%) were MRD-negative (34% of all patients). CR lasting ≥ 60 months was 61%, and the median progression-free survival without the loss of HR was 71.7 months. Hemolytic uremic and capillary leak syndromes were each reported in ≤ 10% of patients, and ≤ 5% had grade 3–4 events; these events were generally reversible. No treatment-related deaths were reported.

Conclusions

Moxetumomab pasudotox resulted in a high rate of durable responses and MRD negativity in heavily pre-treated patients with HCL, with a manageable safety profile. Thus, it represents a new and viable treatment option for patients with R/R HCL, who currently lack adequate therapy.

Trial registration

ClinicalTrials.gov identifier: NCT01829711; first submitted: April 9, 2013. https://clinicaltrials.gov/ct2/show/NCT01829711

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13045-020-01004-y.

Hairy Cell Leukaemia: From Hairy Beginnings to a BRAF New World

For a disease initially described in 1958 as a leukaemic reticulo-endotheliosis associated with poor outcomes, we have come a long way in our understanding of Hairy cell leukaemia. The vast majority of patients diagnosed with this rare, often diagnostically challenging, leukaemia can now expect a lifespan that is similar to the general population. This article covers some of the highlights from the last 6 decades that have led to our current understanding of this fascinating leukaemia - from elucidation of its B-cell origin to discovery of the almost universal occurrence of the BRAF V600E mutation; from the initial successes reported with splenectomy to the more recent development of targeted therapies such as Vemurafenib and Moxetumomab Pasudotox. It also pays tribute to some of the outstanding research in this field focusing particularly on the significant contributions made by the clinical and scientific community in the UK.

Hairy Cell Leukaemia

PURPOSE OF REVIEW

To summarise diagnostic clinical/laboratory findings and highlight differences between classical hairy cell leukaemia (HCLc) and hairy cell leukaemia variant (HCLv). Discussion of prognosis and current treatment indications including novel therapies, linked to understanding of the underlying molecular pathogenesis.

RECENT FINDINGS

Improved understanding of the underlying pathogenesis of HCLc, particularly the causative mutation BRAF V600E, leading to constitutive activation of the MEK/ERK signalling pathway and increased cell proliferation. HCLc is caused by BRAF V600E mutation in most cases. Purine nucleoside analogue (PNA) therapy is the mainstay of treatment, with the addition of rituximab, improving response and minimal residual disease (MRD) clearance. Despite excellent responses to PNAs, many patients will eventually relapse, requiring further therapy. Rarely, patients are refractory to PNA therapy. In relapsed/refractory patients, novel targeted therapies include BRAF inhibitors (BRAFi), anti-CD22 immunoconjugate moxetumomab and Bruton tyrosine kinase inhibitors (BTKi). HCLv has a worse prognosis with median overall survival (OS), only 7-9 years, despite the combination of PNA/rituximab improving front-line response. Moxetumomab or ibrutinib may be a viable treatment but lacks substantial evidence.

Consensus criteria for diagnosis, staging, and treatment response assessment of T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare, mature T-cell neoplasm with a heterogeneous clinical course. With the advent of novel treatment options that will potentially change the management of patients with T-PLL, it has become necessary to produce consensus guidelines for the design and conduct of clinical trials. The T-PLL International Study group (TPLL-ISG) set out to define standardized criteria for diagnosis, treatment indication, and evaluation of response. These criteria will facilitate comparison of results from clinical trials in T-PLL, and will thus support clinical decision making, as well as the approval of new therapeutics by healthcare authorities.

B and T cell prolymphocytic leukaemia

Prolymphocytic leukaemias B-PLL and T-PLL are rare disorders, typically with an aggressive clinical course and poor prognosis. Combining morphology, immunophenotyping, cytogenetic and molecular diagnostics reliably separates B-PLL and T-PLL from one another and other disorders. In T-PLL discovery of frequent mutations in the JAK-STAT pathway have increased understanding of disease pathogenesis. Alemtuzumab (anti-CD52) produces excellent response rates but long-term remissions are only achieved in a minority following consolidation with allogeneic stem cell transplant. Molecular abnormalities in B-PLL are less understood. Disruption of TP53 is a key finding, conveying chemotherapy resistance requiring novel therapies such as B-cell receptor inhibitors (BCRi). Both conditions require improved pathobiological knowledge to identify new treatment targets and guide therapy with novel pathway inhibitors.

Genetic correlation between multiple myeloma and chronic lymphocytic leukaemia provides evidence for shared aetiology

The clustering of different types of B-cell malignancies in families raises the possibility of shared aetiology. To examine this, we performed cross-trait linkage disequilibrium (LD)-score regression of multiple myeloma (MM) and chronic lymphocytic leukaemia (CLL) genome-wide association study (GWAS) data sets, totalling 11,734 cases and 29,468 controls. A significant genetic correlation between these two B-cell malignancies was shown (Rg = 0.4, P = 0.0046). Furthermore, four of the 45 known CLL risk loci were shown to associate with MM risk and five of the 23 known MM risk loci associate with CLL risk. By integrating eQTL, Hi-C and ChIP-seq data, we show that these pleiotropic risk loci are enriched for B-cell regulatory elements and implicate B-cell developmental genes. These data identify shared biological pathways influencing the development of CLL and, MM and further our understanding of the aetiological basis of these B-cell malignancies.

Outcomes following front-line chemotherapy in peripheral T-cell lymphoma: 10-year experience at The Royal Marsden and The Christie Hospital

We evaluated the outcomes for patients with peripheral T-cell lymphoma (PTCL) undergoing front-line chemotherapy at our institutions between 2002 and 2012. One hundred and fifty-six patients were eligible, comprising PTCL not otherwise specified (NOS) (n = 50, 32.0%), angioimmunoblastic T-cell lymphoma (AITL) (n = 44, 28.2%), anaplastic large-cell lymphoma (ALCL) ALK negative (n = 23, 14.7%), ALCL ALK positive (n = 16, 10.3%), and other (n = 23, 14.7%). Most patients received CHOP (66.0%) and 13.0% received an autologous hematopoietic progenitor cell transplant (HPCT). With a median follow-up of 63.4 months, 5-year overall survival (OS) and progression-free survival (PFS) was 38.8% and 19.8% respectively. Independent risk factors for inferior OS were age >60 years, International Prognostic Index (IPI) ≥ 2 and lack of complete response to induction. When responding patients were compared by receipt of an autologous HPCT versus not, HPCT was associated with improved PFS (p = .001) and OS (p = .046) and remained significant for PFS in multivariate analysis suggesting a possible therapeutic benefit.

Haemophagocytic lymphohistiocytosis as a consequence of untreated B-cell chronic lymphocytic leukaemia

Haemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening syndrome characterised by defective cytotoxic function and hypercytokinaemia leading to macrophage expansion and haemophagocytosis. Patients often present with unexplained fevers, hepatosplenomegaly and pancytopenia, with elevation in serum ferritin and triglyceride. Acquired forms are triggered by infection, malignancy or rheumatological disorders. HLH in the setting of chronic lymphocytic leukaemia is rarely reported, however, and is usually associated with infection or as a consequence of chemotherapy. We present a case of HLH in a 64-year-old Caucasian woman with the only identified trigger being her hitherto untreated CLL.

Genome-wide association analysis implicates dysregulation of immunity genes in chronic lymphocytic leukaemia

Several chronic lymphocytic leukaemia (CLL) susceptibility loci have been reported; however, much of the heritable risk remains unidentified. Here we perform a meta-analysis of six genome-wide association studies, imputed using a merged reference panel of 1,000 Genomes and UK10K data, totalling 6,200 cases and 17,598 controls after replication. We identify nine risk loci at 1p36.11 (rs34676223, P=5.04 × 10-13), 1q42.13 (rs41271473, P=1.06 × 10-10), 4q24 (rs71597109, P=1.37 × 10-10), 4q35.1 (rs57214277, P=3.69 × 10-8), 6p21.31 (rs3800461, P=1.97 × 10-8), 11q23.2 (rs61904987, P=2.64 × 10-11), 18q21.1 (rs1036935, P=3.27 × 10-8), 19p13.3 (rs7254272, P=4.67 × 10-8) and 22q13.33 (rs140522, P=2.70 × 10-9). These new and established risk loci map to areas of active chromatin and show an over-representation of transcription factor binding for the key determinants of B-cell development and immune response.

Consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia

Hairy cell leukemia is an uncommon hematologic malignancy characterized by pancytopenia and marked susceptibility to infection. Tremendous progress in the management of patients with this disease has resulted in high response rates and improved survival, yet relapse and an appropriate approach to re-treatment present continuing areas for research. The disease and its effective treatment are associated with immunosuppression. Because more patients are being treated with alternative programs, comparison of results will require general agreement on definitions of response, relapse, and methods of determining minimal residual disease. The development of internationally accepted, reproducible criteria is of paramount importance in evaluating and comparing clinical trials to provide optimal care. Despite the success achieved in managing these patients, continued participation in available clinical trials in the first-line and particularly in the relapse setting is highly recommended. The Hairy Cell Leukemia Foundation convened an international conference to provide common definitions and structure to guide current management. There is substantial opportunity for continued research in this disease. In addition to the importance of optimizing the prevention and management of the serious risk of infection, organized evaluations of minimal residual disease and treatment at relapse offer ample opportunities for clinical research. Finally, a scholarly evaluation of quality of life in the increasing number of survivors of this now manageable chronic illness merits further study. The development of consensus guidelines for this disease offers a framework for continued enhancement of the outcome for patients.

Genetics and Prognostication in Splenic Marginal Zone Lymphoma: Revelations from Deep Sequencing

PURPOSE

Mounting evidence supports the clinical significance of gene mutations and immunogenetic features in common mature B-cell malignancies.

EXPERIMENTAL DESIGN

We undertook a detailed characterization of the genetic background of splenic marginal zone lymphoma (SMZL), using targeted resequencing and explored potential clinical implications in a multinational cohort of 175 patients with SMZL.

RESULTS

We identified recurrent mutations in TP53 (16%), KLF2 (12%), NOTCH2 (10%), TNFAIP3 (7%), MLL2 (11%), MYD88 (7%), and ARID1A (6%), all genes known to be targeted by somatic mutation in SMZL. KLF2 mutations were early, clonal events, enriched in patients with del(7q) and IGHV1-2*04 B-cell receptor immunoglobulins, and were associated with a short median time to first treatment (0.12 vs. 1.11 years; P = 0.01). In multivariate analysis, mutations in NOTCH2 [HR, 2.12; 95% confidence interval (CI), 1.02-4.4; P = 0.044] and 100% germline IGHV gene identity (HR, 2.19; 95% CI, 1.05-4.55; P = 0.036) were independent markers of short time to first treatment, whereas TP53 mutations were an independent marker of short overall survival (HR, 2.36; 95 % CI, 1.08-5.2; P = 0.03).

CONCLUSIONS

We identify key associations between gene mutations and clinical outcome, demonstrating for the first time that NOTCH2 and TP53 gene mutations are independent markers of reduced treatment-free and overall survival, respectively.

Rituximab-induced Takotsubo syndrome: more cardiotoxic than it appears?

Rituximab is used for treatment of multiple haematological cancers. Caution for use is advised in patients with significant cardiorespiratory disease due to known cases of exacerbations of angina and arrhythmias. However, its cardiotoxicity profile is not as well recognised as other monoclonal antibodies such as transtuzumab. We report a case of a 66-year-old man who developed Takotsubo's cardiomyopathy (TC) after an elective infusion of rituximab. This case is exceptional in that rituximab has not been linked to TC, and the vast majority of chemotherapy-linked and immunotherapy-linked TC reactions have occurred during initial infusions. We also discuss the different mechanisms which link TC to immunotherapy and chemotherapy, and propose that there may be a potential for risk-stratifying recipients of this frequently used immunotherapy prior to administering treatment.

Rituximab, Gemcitabine, Cisplatin and Methylprednisolone (R-GEM-P) is an effective regimen in relapsed diffuse large B-cell lymphoma

BACKGROUND

Patients with relapsed diffuse large B-cell lymphoma (DLBCL) have a poor prognosis. Gemcitabine, methylprednisolone, cisplatin +/- rituximab (GEM-P+/-R) is a salvage regimen with limited overlap in toxicity with first-line therapy and short duration of inpatient delivery.

METHODS

We assessed the efficacy and safety of GEM-P+/-R in a retrospective single-centre analysis including patients meeting criteria of ≥ 18 yr of age, histologically proven DLBCL, treated between 2001 and 2011 in second-line with gemcitabine 1000 mg/m(2) day 1, 8 and 15, methylprednisolone 1000 mg day 1-5, cisplatin 100 mg/m(2) day 15 (replaced with carboplatin AUC5 if contraindication/toxicity) +/- rituximab 375 mg/m(2) day 1 and 15, every 28 d.

RESULTS

Forty-five patients aged 25-74 received a median of three cycles of GEM-P+/-R; 64% received rituximab. In 44 evaluable patients receiving GEM-P+/-R, overall response rate (ORR) was 48%; in 28 evaluable patients treated with rituximab + GEM-P (R-GEM-P), ORR was 61%. With median follow-up of 50.5 months (95% CI: 28.3-72.7), 3-yr overall survival (OS) from start of GEM-P+/-R was 31.4% (95% CI: 16.5-46.3); in patients treated with R-GEM-P, 3-yr OS was 49.1% (95% CI: 28.7-69.5). Predominant grade ≥ 3 toxicities were haematological; thrombocytopenia 69%, neutropenia 60% and febrile neutropenia 7%.

CONCLUSION

R-GEM-P is a deliverable regimen with useful activity in second-line treatment of DLBCL. Our data suggest that rituximab should be given concurrently.

Management of prolymphocytic leukemia

B-cell (B-PLL) and T-cell (T-PLL) prolymphocytic leukemias are rare, poor-prognosis lymphoid neoplasms with similar presentation characterized by symptomatic splenomegaly and lymphocytosis. They can be distinguished from each other and from other T- and B-cell leukemias by careful evaluation of morphology, immunophenotyping, and molecular genetics. The clinical behavior is typically aggressive, although a subset of patients may have an indolent phase of variable length. First-line therapy for T-PLL is with intravenous alemtuzumab and for B-PLL is with combination purine analog-based chemo-immunotherapy. New B-cell receptor inhibitors, such as ibrutinib and idelalisib, may have a role in the management of B-PLL, especially for the patients harboring abnormalities of TP53. Allogenic stem cell transplantation should still be considered for eligible patients and may be the only current therapy capable of delivering a cure. In the past few years, many of the molecular mechanisms underlying disease pathogenesis and progression have been revealed and are likely to lead to the development of novel targeted approaches.

Therapeutic options in relapsed or refractory peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) represents a relatively rare group of heterogeneous non-Hodgkin lymphomas with a very poor prognosis. Current therapies, based on historical regimens for aggressive B-cell lymphomas, have resulted in insufficient patient outcomes. The majority of patients relapse rapidly, and current 5-year overall survival rates are only 10-30%. It is evident that new approaches to treat patients with PTCL are required. In recent years, prospective studies in PTCL have been initiated, mainly in patients with relapsed/refractory disease. In some of these, selected histologic subtypes have been evaluated in detail. As a consequence, numerous new therapies have been developed and shown activity in PTCL, including: agents targeting the immune system (e.g. brentuximab vedotin, alemtuzumab, lenalidomide); histone deacetylase inhibitors (romidepsin, belinostat); antifolates (pralatrexate); fusion proteins (denileukin diftitox); nucleoside analogs (pentostatin, gemcitabine); and other agents (e.g. alisertib, plitidepsin, bendamustine, bortezomib). A variety of interesting novel combinations is also emerging. It is hoped that these innovative approaches, coupled with a greater understanding of the clinicopathologic features, pathogenesis, molecular biology, and natural history of PTCL will advance the field and improve outcomes in this challenging group of diseases. This review summarizes the currently available clinical evidence on the various approaches to treating relapsed/refractory PTCL, including the role of stem cell transplantation, with an emphasis on potential new drug therapies.

Ibrutinib versus ofatumumab in previously treated chronic lymphoid leukemia

BACKGROUND

In patients with chronic lymphoid leukemia (CLL) or small lymphocytic lymphoma (SLL), a short duration of response to therapy or adverse cytogenetic abnormalities are associated with a poor outcome. We evaluated the efficacy of ibrutinib, a covalent inhibitor of Bruton's tyrosine kinase, in patients at risk for a poor outcome.

METHODS

In this multicenter, open-label, phase 3 study, we randomly assigned 391 patients with relapsed or refractory CLL or SLL to receive daily ibrutinib or the anti-CD20 antibody ofatumumab. The primary end point was the duration of progression-free survival, with the duration of overall survival and the overall response rate as secondary end points.

RESULTS

At a median follow-up of 9.4 months, ibrutinib significantly improved progression-free survival; the median duration was not reached in the ibrutinib group (with a rate of progression-free survival of 88% at 6 months), as compared with a median of 8.1 months in the ofatumumab group (hazard ratio for progression or death in the ibrutinib group, 0.22; P<0.001). Ibrutinib also significantly improved overall survival (hazard ratio for death, 0.43; P=0.005). At 12 months, the overall survival rate was 90% in the ibrutinib group and 81% in the ofatumumab group. The overall response rate was significantly higher in the ibrutinib group than in the ofatumumab group (42.6% vs. 4.1%, P<0.001). An additional 20% of ibrutinib-treated patients had a partial response with lymphocytosis. Similar effects were observed regardless of whether patients had a chromosome 17p13.1 deletion or resistance to purine analogues. The most frequent nonhematologic adverse events were diarrhea, fatigue, pyrexia, and nausea in the ibrutinib group and fatigue, infusion-related reactions, and cough in the ofatumumab group.

CONCLUSIONS

Ibrutinib, as compared with ofatumumab, significantly improved progression-free survival, overall survival, and response rate among patients with previously treated CLL or SLL. (Funded by Pharmacyclics and Janssen; RESONATE ClinicalTrials.gov number, NCT01578707.).

GEM-P chemotherapy is active in the treatment of relapsed Hodgkin lymphoma

Hodgkin lymphoma (HL) is a relatively chemosensitive malignancy. However, for those who relapse, high-dose chemotherapy with autologous stem cell transplant is the treatment of choice which relies on adequate disease control with salvage chemotherapy. Regimens commonly used often require inpatient administration and can be difficult to deliver due to toxicity. Gemcitabine and cisplatin have activity in HL, non-overlapping toxicity with first-line chemotherapeutics, and may be delivered in an outpatient setting. In this retrospective single-centre analysis, patients with relapsed or refractory HL treated with gemcitabine 1,000 mg/m(2) day (D)1, D8 and D15; methylprednisolone 1,000 mg D1-5; and cisplatin 100 mg/m(2) D15, every 28 days (GEM-P) were included. Demographic, survival, response and toxicity data were recorded. Forty-one eligible patients were identified: median age 27. One hundred and twenty-two cycles of GEM-P were administered in total (median 3 cycles; range 1-6). Twenty of 41 (48 %) patients received GEM-P as second-line treatment and 11/41 (27 %) as third-line therapy. Overall response rate (ORR) to GEM-P in the entire cohort was 80 % (complete response (CR) 37 %, partial response 44 %) with 14/15 CR confirmed as a metabolic CR on PET and ORR of 85 % in the 20 second-line patients. The most common grade 3/4 toxicities were haematological: neutropenia 54 % and thrombocytopenia 51 %. Median follow-up from the start of GEM-P was 4.5 years. Following GEM-P, 5-year progression-free survival was 46 % (95 % confidence interval (CI), 30-62 %) and 5-year overall survival was 59 % (95 % CI, 43-74 %). Fourteen of 41 patients proceeded directly to autologous transplant. GEM-P is a salvage chemotherapy with relatively high response rates, leading to successful transplantation in appropriate patients, in the treatment of relapsed or refractory HL.

A genome-wide association study identifies multiple susceptibility loci for chronic lymphocytic leukemia

Genome-wide association studies (GWAS) of chronic lymphocytic leukemia (CLL) have shown that common genetic variation contributes to the heritable risk of CLL. To identify additional CLL susceptibility loci, we conducted a GWAS and performed a meta-analysis with a published GWAS totaling 1,739 individuals with CLL (cases) and 5,199 controls with validation in an additional 1,144 cases and 3,151 controls. A combined analysis identified new susceptibility loci mapping to 3q26.2 (rs10936599, P = 1.74 × 10(-9)), 4q26 (rs6858698, P = 3.07 × 10(-9)), 6q25.2 (IPCEF1, rs2236256, P = 1.50 × 10(-10)) and 7q31.33 (POT1, rs17246404, P = 3.40 × 10(-8)). Additionally, we identified a promising association at 5p15.33 (CLPTM1L, rs31490, P = 1.72 × 10(-7)) and validated recently reported putative associations at 5p15.33 (TERT, rs10069690, P = 1.12 × 10(-10)) and 8q22.3 (rs2511714, P = 2.90 × 10(-9)). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to CLL.

Functional analysis of the ATM-p53-p21 pathway in the LRF CLL4 trial: blockade at the level of p21 is associated with short response duration

PURPOSE

This study sought to establish whether functional analysis of the ATM-p53-p21 pathway adds to the information provided by currently available prognostic factors in patients with chronic lymphocytic leukemia (CLL) requiring frontline chemotherapy.

EXPERIMENTAL DESIGN

Cryopreserved blood mononuclear cells from 278 patients entering the LRF CLL4 trial comparing chlorambucil, fludarabine, and fludarabine plus cyclophosphamide were analyzed for ATM-p53-p21 pathway defects using an ex vivo functional assay that uses ionizing radiation to activate ATM and flow cytometry to measure upregulation of p53 and p21 proteins. Clinical endpoints were compared between groups of patients defined by their pathway status.

RESULTS

ATM-p53-p21 pathway defects of four different types (A, B, C, and D) were identified in 194 of 278 (70%) samples. The type A defect (high constitutive p53 expression combined with impaired p21 upregulation) and the type C defect (impaired p21 upregulation despite an intact p53 response) were each associated with short progression-free survival. The type A defect was associated with chemoresistance, whereas the type C defect was associated with early relapse. As expected, the type A defect was strongly associated with TP53 deletion/mutation. In contrast, the type C defect was not associated with any of the other prognostic factors examined, including TP53/ATM deletion, TP53 mutation, and IGHV mutational status. Detection of the type C defect added to the prognostic information provided by TP53/ATM deletion, TP53 mutation, and IGHV status.

CONCLUSION

Our findings implicate blockade of the ATM-p53-p21 pathway at the level of p21 as a hitherto unrecognized determinant of early disease recurrence following successful cytoreduction.