Roles of PI3Kγ and PI3Kδ in mantle cell lymphoma proliferation and migration contributing to efficacy of the PI3Kγ/δ inhibitor duvelisib.

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma that is incurable with existing therapies, and therefore presents a significant unmet clinical need. The ability of this disease to overcome therapy, including those that target the B cell receptor pathway which has a pathogenic role in MCL, highlights the need to develop new treatment strategies. Herein, we demonstrate that a distinguishing feature of lymph node resident MCL cells is the expression of phosphatidylinositol 3-kinase γ (PI3Kγ), a PI3K isoform that is not highly expressed in other B cells or B-cell malignancies. By exploring the role of PI3K in MCL using different PI3K isoform inhibitors, we provide evidence that duvelisib, a dual PI3Kδ/γ inhibitor, has a greater effect than PI3Kδ- and PI3Kγ-selective inhibitors in blocking the proliferation of primary MCL cells and MCL cell lines, and in inhibiting tumour growth in a mouse xenograft model. In addition, we demonstrated that PI3Kδ/γ signalling is critical for migration of primary MCL cells and cell lines. Our data indicates that aberrant expression of PI3Kγ is a critical feature of MCL pathogenesis. Thus, we suggest that the dual PI3Kδ/γ duvelisib would be effective for the treatment of mantle cell lymphoma.

Whole-genome sequencing of chronic lymphocytic leukemia identifies subgroups with distinct biological and clinical features.

The value of genome-wide over targeted driver analyses for predicting clinical outcomes of cancer patients is debated. Here, we report the whole-genome sequencing of 485 chronic lymphocytic leukemia patients enrolled in clinical trials as part of the United Kingdom's 100,000 Genomes Project. We identify an extended catalog of recurrent coding and noncoding genetic mutations that represents a source for future studies and provide the most complete high-resolution map of structural variants, copy number changes and global genome features including telomere length, mutational signatures and genomic complexity. We demonstrate the relationship of these features with clinical outcome and show that integration of 186 distinct recurrent genomic alterations defines five genomic subgroups that associate with response to therapy, refining conventional outcome prediction. While requiring independent validation, our findings highlight the potential of whole-genome sequencing to inform future risk stratification in chronic lymphocytic leukemia.

COVID-19 outcomes in haematopoietic cell transplant recipients: A systematic review and meta-analysis.

Up-to-date information on coronavirus disease 2019 (COVID-19) outcomes and risk factors in haematopoietic cell transplantation (HCT) recipients is required to inform on decisions about cancer treatment and COVID-19 mitigation strategies. We performed a meta-analysis to address this knowledge gap. All studies with at least five patients who reported COVID-19-related deaths in HCT recipients were included. The primary outcome was COVID-19-related death. Secondary outcomes were COVID-19-related mechanical ventilation (MV) and intensive care unit (ITU) admission. The cumulative COVID-19-related death rate among HCT recipients was 21% (95% confidence interval [CI] 18%-24%), while MV and ITU admission rates were 14% (95% CI 11%-17%) and 18% (95% CI 14%-22%), respectively. Subgroup analysis showed higher death rates in patients who developed COVID-19 within 12 months of HCT (risk ratio [RR] 1.82, 95% CI 1.09-3.03), within 6 months of receiving immunosuppressant drugs (RR 2.11, 95% CI 1.38-3.20) or in the context of active graft-versus-host disease (RR 2.38, 95% CI 1.10-5.16). Our findings support the idea that HCT should remain an integral part of cancer treatment during the COVID-19 pandemic but also highlight the need to prioritise preventative measures in those patients who are at increased risk of adverse COVID-19 outcomes.

Patient and health practitioner views and experiences of a cancer trial before and during COVID-19: qualitative study.

BACKGROUND: Understanding patient and health practitioner perspectives on clinical trials can inform opportunities to enhance trial conduct and design, and therefore patient experience. Patients with haematological cancers have faced additional risk and uncertainty during the pandemic but it is unclear how they and practitioners have experienced cancer trials during this period. In the context of a haemato-oncology trial (PETReA), we compared patient and practitioner views and experiences of PETReA before and during COVID-19. METHODS: Qualitative study embedded within PETReA. Semi-structured interviews (N=41) with patients and practitioners from 16 NHS sites before (n=17) and during the first wave of COVID-19 (n=24). Analysis drew on the framework approach. RESULTS: Practitioners acknowledged the need for the trial to continue during the pandemic but their treatment preferences altered, becoming more pronounced for patients who had a favourable response to induction treatment, while staying unchanged for patients with a less favourable response. Practitioners commented that COVID-19 meant the evidence base for the trial arms was lacking or mixed, but that it likely increased the risks of maintenance treatment for patients with a favourable response to induction treatment. While only one participant interviewed withdrew from PETReA during the pandemic, others said they would consider withdrawing if information that they were at increased risk of severe illness from COVID-19 became available. During COVID-19, patients described less frequent contact with the trial team, which left some feeling less clear about their trial pathway. However, several described having in-depth, collaborative discussions with practitioners about the risks and benefits of randomisation in the context of COVID-19. Patients valued these discussions and were reassured by the emphasis practitioners placed on patients being free to withdraw if circumstances changed, and this helped patients feel comfortable about continuing in PETReA. CONCLUSIONS: The findings point to ways trial communication can support patients to feel comfortable about continuing in a trial during uncertain times, including adopting a more in-depth, collaborative exploration of the risks and benefits of trial arms with patients and emphasising voluntariness. The results are relevant to trialists recruiting patients who are clinically extremely vulnerable or are at increased risk of poor COVID-19 outcomes despite being vaccinated.

Is it time for PET-guided therapy in follicular lymphoma?

18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) is now established as the gold-standard imaging modality for both staging and response assessment in follicular lymphoma (FL). In this Perspective, we propose where PET can, and cannot, guide clinicians in their therapeutic approach. PET at diagnosis and pretreatment is important for staging, with greater sensitivity compared with standard CT, and consequent improved outcomes in truly limited-stage FL. Small data sets suggesting that a high baseline standardized uptake value (SUVmax) identifies de novo histologic transformation (HT) have not been corroborated by data from GALLIUM, the largest prospective study to examine modern therapies for FL. Nonetheless, the role of baseline quantitative PET measures requires further clarification. The median survival of patients with newly diagnosed FL is now potentially >20 years. Treatment of symptomatic FL aims to achieve remission and optimize quality of life for as long as possible, with many patients achieving a "functional cure" at the cost of unwanted treatment effects. Several studies have identified end-of-induction (EOI) PET after initial chemoimmunotherapy in patients with a high tumor burden as strongly predictive of both progression-free and overall survival, and EOI PET is being evaluated as a platform for response-adapted treatment. Unmet needs remain: improving the inferior survival for patients remaining PET positive and quantifying the progression-free survival and time to next treatment advantage, and additional toxicity of anti-CD20 maintenance in patients who achieve complete metabolic remission. In the absence of an overall survival advantage for frontline antibody maintenance, the question of using PET to guide the therapeutic approach is more important than ever in the context of the COVID-19 pandemic.

Kinobead Profiling Reveals Reprogramming of BCR Signaling in Response to Therapy within Primary CLL Cells.

PURPOSE: B-cell receptor (BCR) signaling is critical for the pathogenesis of chronic lymphocytic leukemia (CLL), promoting both malignant cell survival and disease progression. Although vital, understanding of the wider signaling network associated with malignant BCR stimulation is poor. This is relevant with respect to potential changes in response to therapy, particularly involving kinase inhibitors. In the current study, we describe a novel high-resolution approach to investigate BCR signaling in primary CLL cells and track the influence of therapy on signaling response. EXPERIMENTAL DESIGN: A kinobead/mass spectrometry-based protocol was used to study BCR signaling in primary CLL cells. Longitudinal analysis of samples donated by clinical trial patients was used to investigate the impact of chemoimmunotherapy and ibrutinib on signaling following surface IgM engagement. Complementary Nanostring and immunoblotting analysis was used to verify our findings. RESULTS: Our protocol isolated a unique, patient-specific signature of over 30 kinases from BCR-stimulated CLL cells. This signature was associated with 13 distinct Kyoto Encyclopedia of Genes and Genomes pathways and showed significant change in cells from treatment-naïve patients compared with those from patients who had previously undergone therapy. This change was validated by longitudinal analysis of clinical trials samples where BCR-induced kinome responses in CLL cells altered between baseline and disease progression in patients failing chemoimmunotherapy and between baseline and treatment in patients taking ibrutinib. CONCLUSIONS: These data comprise the first comprehensive proteomic investigation of the BCR signaling response within CLL cells and reveal unique evidence that these cells undergo adaptive reprogramming of this signaling in response to therapy.

Assessing technical and biological variation in SWATH-MS-based proteomic analysis of chronic lymphocytic leukaemia cells.

Chronic lymphocytic leukaemia (CLL) exhibits variable clinical course and response to therapy, but the molecular basis of this variability remains incompletely understood. Data independent acquisition (DIA)-MS technologies, such as SWATH (Sequential Windowed Acquisition of all THeoretical fragments), provide an opportunity to study the pathophysiology of CLL at the proteome level. Here, a CLL-specific spectral library (7736 proteins) is described alongside an analysis of sample replication and data handling requirements for quantitative SWATH-MS analysis of clinical samples. The analysis was performed on 6 CLL samples, incorporating biological (IGHV mutational status), sample preparation and MS technical replicates. Quantitative information was obtained for 5169 proteins across 54 SWATH-MS acquisitions: the sources of variation and different computational approaches for batch correction were assessed. Functional enrichment analysis of proteins associated with IGHV mutational status showed significant overlap with previous studies based on gene expression profiling. Finally, an approach to perform statistical power analysis in proteomics studies was implemented. This study provides a valuable resource for researchers working on the proteomics of CLL. It also establishes a sound framework for the design of sufficiently powered clinical proteomics studies. Indeed, this study shows that it is possible to derive biologically plausible hypotheses from a relatively small dataset.

Development of a cell-line model to mimic the pro-survival effect of nurse-like cells in chronic lymphocytic leukemia.

The interaction between Chronic lymphocytic leukemia (CLL) cells and monocyte-derived nurse-like cells (NLCs) is fundamentally important to CLL biology. However, studies of how CLL cells and NLCs interact have been hampered by the need for freshly obtained CLL blood samples, coupled with wide variation in the number of monocytes present in the blood of individual patients. Here, we report the development and validation of a cell-line model of NLCs which overcomes these difficulties. Co-culture of primary CLL cells with THP-1 cells induced to differentiate into macrophages by phorbol 12-myristate 13-acetate (PMA) significantly reduced both spontaneous and fludarabine-induced cell death of leukemic cells. Furthermore, compared with their M1-polarized counterparts, M2-polarized macrophages derived from PMA-differentiated THP-1 cells conferred to CLL cells greater protection from spontaneous and fludarabine-induced apoptosis. Since NLCs resemble M2 tumor-associated macrophages, this cell-line model could be useful for investigating the mechanisms through which NLCs protect CLL cells from spontaneous and drug-induced apoptosis.

Clinical significance of DNA methylation in chronic lymphocytic leukemia patients: results from 3 UK clinical trials.

Chronic lymphocytic leukemia patients with mutated immunoglobulin heavy-chain genes (IGHV-M), particularly those lacking poor-risk genomic lesions, often respond well to chemoimmunotherapy (CIT). DNA methylation profiling can subdivide early-stage patients into naive B-cell-like CLL (n-CLL), memory B-cell-like CLL (m-CLL), and intermediate CLL (i-CLL), with differing times to first treatment and overall survival. However, whether DNA methylation can identify patients destined to respond favorably to CIT has not been ascertained. We classified treatment-naive patients (n = 605) from 3 UK chemo and CIT clinical trials into the 3 epigenetic subgroups, using pyrosequencing and microarray analysis, and performed expansive survival analysis. The n-CLL, i-CLL, and m-CLL signatures were found in 80% (n = 245/305), 17% (53/305), and 2% (7/305) of IGHV-unmutated (IGHV-U) cases, respectively, and in 9%, (19/216), 50% (108/216), and 41% (89/216) of IGHV-M cases, respectively. Multivariate Cox proportional analysis identified m-CLL as an independent prognostic factor for overall survival (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.24-0.87; P = .018) in CLL4, and for progression-free survival (HR, 0.25; 95% CI, 0.10-0.57; P = .002) in ARCTIC and ADMIRE patients. The analysis of epigenetic subgroups in patients entered into 3 first-line UK CLL trials identifies m-CLL as an independent marker of prolonged survival and may aid in the identification of patients destined to demonstrate prolonged survival after CIT.

Final Results of a Randomized, Phase III Study of Rituximab With or Without Idelalisib Followed by Open-Label Idelalisib in Patients With Relapsed Chronic Lymphocytic Leukemia.

PURPOSE: A randomized, double-blind, phase III study of idelalisib (IDELA) plus rituximab versus placebo plus rituximab in patients with relapsed chronic lymphocytic leukemia (CLL) was terminated early because of superior efficacy of the IDELA-plus-rituximab (IDELA/R) arm. Patients in either arm could then enroll in an extension study to receive IDELA monotherapy. Here, we report the long-term efficacy and safety data for IDELA-treated patients across the primary and extension studies. PATIENTS AND METHODS: Patients were randomly assigned to receive rituximab in combination with either IDELA 150 mg twice daily (IDELA/R; n = 110) or placebo (placebo/R; n = 110). Key end points were progression-free survival (PFS), overall response rate (ORR), overall survival (OS), and safety. RESULTS: The long-term efficacy and safety of treatment with IDELA was assessed in 110 patients who received at least one dose of IDELA in the primary study, 75 of whom enrolled in the extension study. The IDELA/R-to-IDELA group had a median PFS of 20.3 months (95% CI, 17.3 to 26.3 months) after a median follow-up time of 18 months (range, 0.3 to 67.6 months). The ORR was 85.5% (94 of 110 patients; n = 1 complete response). The median OS was 40.6 months (95% CI, 28.5 to 57.3 months) and 34.6 months (95% CI, 16.0 months to not reached) for patients randomly assigned to the IDELA/R and placebo/R groups, respectively. Prolonged exposure to IDELA increased the incidence of all-grade, grade 2, and grade 3 or greater diarrhea (46.4%, 17.3%, and 16.4%, respectively), all-grade and grade 3 or greater colitis (10.9% and 8.2%, respectively) and all-grade and grade 3 or greater pneumonitis (10.0% and 6.4%, respectively) but did not increase the incidence of elevated hepatic aminotransferases. CONCLUSION: IDELA improved PFS and OS compared with rituximab alone in patients with relapsed CLL. Long-term IDELA was effective and had an expected safety profile. No new IDELA-related adverse events were identified with longer exposure.

DYNAMO: A Phase II Study of Duvelisib (IPI-145) in Patients With Refractory Indolent Non-Hodgkin Lymphoma.

PURPOSE: Indolent non-Hodgkin lymphoma (iNHL) remains largely incurable and often requires multiple lines of treatment after becoming refractory to standard therapies. Duvelisib was approved by the Food and Drug Administration for relapsed or refractory (RR) chronic lymphocytic leukemia or small lymphocytic lymphoma (SLL) and RR follicular lymphoma (FL) after two or more prior systemic therapies. On the basis of the activity of duvelisib, a first-in-class oral dual inhibitor of phosphoinositide 3-kinase-δ,-γ, in RR iNHL in a phase I study, the safety and efficacy of duvelisib monotherapy was evaluated in iNHL refractory to rituximab and either chemotherapy or radioimmunotherapy. PATIENTS AND METHODS: Eligible patients had measurable iNHL (FL, SLL, or marginal zone B-cell lymphoma) double refractory to rituximab (monotherapy or in combination) and to either chemotherapy or radioimmunotherapy. All were treated with duvelisib 25 mg orally twice daily in 28-day cycles until progression, unacceptable toxicity, or death. The primary end point was overall response rate (ORR) using the revised International Working Group criteria for malignant lymphoma. RESULTS: This open-label, global phase II trial enrolled 129 patients (median age, 65 years; median of three prior lines of therapy) with an ORR of 47.3% (SLL, 67.9%; FL, 42.2%; MZL, 38.9%). The estimated median duration of response was 10 months, and the estimated median progression-free survival was 9.5 months. The most frequent any-grade treatment-emergent adverse events (TEAEs) were diarrhea (48.8%), nausea (29.5%), neutropenia (28.7%), fatigue (27.9%), and cough (27.1%). Among the 88.4% of patients with at least one grade 3 or greater TEAE, the most common TEAEs were neutropenia (24.8%), diarrhea (14.7%), anemia (14.7%), and thrombocytopenia (11.6%). CONCLUSION: In the DYNAMO study, oral duvelisib monotherapy demonstrated clinically meaningful activity and a manageable safety profile in heavily pretreated, double-refractory iNHL, consistent with previous observations. Duvelisib may provide a new oral treatment option for this patient population of which many are elderly and in need of additional therapies.

Delineating the distinct role of AKT in mediating cell survival and proliferation induced by CD154 and IL-4/IL-21 in chronic lymphocytic leukemia.

The functional significance of AKT in chronic lymphocytic leukemia (CLL) remains unclear. Given the importance of non-malignant T cells in regulating clonal expansion in CLL, we investigated the role of AKT in T cell-mediated cytoprotection and proliferation using an established co-culture system in which primary CLL cells were incubated on a monolayer of transfected mouse fibroblasts expressing human CD40L (CD154). Stimulation of CLL cells via CD40 induced activation of AKT, which was closely associated with downregulation of its negative regulator PTEN, and protected CLL cells from killing by bendamustine. This cytoprotective effect of CD40 stimulation was prevented by a selective inhibitor of AKT. Stimulation of CLL cells with CD154 + IL-4 or IL-21 induced proliferation detected as reduced fluorescence of cells pre-stained with CFSE. AKT inhibition produced a significant, consistent reduction in proliferation induced by CD154 + IL-4 and a reduction in proliferation induced by CD154 + IL-21 in most but not all cases. In contrast, AKT inhibition had no effect on the proliferation of normal B cells induced by CD154 + IL-4 or IL-21. These findings indicate that AKT contributes in a significant way to T-cell mediated survival and proliferation signalling in CLL and support the clinical evaluation of AKT inhibitors in this disease.

Lck is a relevant target in chronic lymphocytic leukaemia cells whose expression variance is unrelated to disease outcome.

Pathogenesis of chronic lymphocytic leukaemia (CLL) is contingent upon antigen receptor (BCR) expressed by malignant cells of this disease. Studies on somatic hypermutation of the antigen binding region, receptor expression levels and signal capacity have all linked BCR on CLL cells to disease prognosis. Our previous work showed that the src-family kinase Lck is a targetable mediator of BCR signalling in CLL cells, and that variance in Lck expression associated with ability of BCR to induce signal upon engagement. This latter finding makes Lck similar to ZAP70, another T-cell kinase whose aberrant expression in CLL cells also associates with BCR signalling capacity, but also different because ZAP70 is not easily pharmacologically targetable. Here we describe a robust method of measuring Lck expression in CLL cells using flow cytometry. However, unlike ZAP70 whose expression in CLL cells predicts prognosis, we find Lck expression and disease outcome in CLL are unrelated despite observations that its inhibition produces effects that biologically resemble the egress phenotype taken on by CLL cells treated with idelalisib. Taken together, our findings provide insight into the pathobiology of CLL to suggest a more complex relationship between expression of molecules within the BCR signalling pathway and disease outcome.

Genome-wide association analysis of chronic lymphocytic leukaemia, Hodgkin lymphoma and multiple myeloma identifies pleiotropic risk loci.

B-cell malignancies (BCM) originate from the same cell of origin, but at different maturation stages and have distinct clinical phenotypes. Although genetic risk variants for individual BCMs have been identified, an agnostic, genome-wide search for shared genetic susceptibility has not been performed. We explored genome-wide association studies of chronic lymphocytic leukaemia (CLL, N = 1,842), Hodgkin lymphoma (HL, N = 1,465) and multiple myeloma (MM, N = 3,790). We identified a novel pleiotropic risk locus at 3q22.2 (NCK1, rs11715604, P = 1.60 × 10-9) with opposing effects between CLL (P = 1.97 × 10-8) and HL (P = 3.31 × 10-3). Eight established non-HLA risk loci showed pleiotropic associations. Within the HLA region, Ser37 + Phe37 in HLA-DRB1 (P = 1.84 × 10-12) was associated with increased CLL and HL risk (P = 4.68 × 10-12), and reduced MM risk (P = 1.12 × 10-2), and Gly70 in HLA-DQB1 (P = 3.15 × 10-10) showed opposing effects between CLL (P = 3.52 × 10-3) and HL (P = 3.41 × 10-9). By integrating eQTL, Hi-C and ChIP-seq data, we show that the pleiotropic risk loci are enriched for B-cell regulatory elements, as well as an over-representation of binding of key B-cell transcription factors. These data identify shared biological pathways influencing the development of CLL, HL and MM. The identification of these risk loci furthers our understanding of the aetiological basis of BCMs.