Natalie Galanina

Heightened BTK-dependent cell proliferation in unmutated chronic lymphocytic leukemia confers increased sensitivity to ibrutinib

In chronic lymphocytic leukemia (CLL), patients with unmutated immunoglobulin heavy chain variable region gene (UM-CLL) have worse outcomes than mutated CLL (M-CLL) following chemotherapy or chemoimmunotherapy. However, in the era of BCR-targeted therapies, the adverse prognostic impact of unmutated IGHV seems to be diminishing, and there are clinical datasets showing unexpected improved responses in UM-CLL. We investigated the biological differences of BTK activity between these subgroups and further compared the impact of ibrutinib on molecular and cellular behaviors. Immunoblotting analysis revealed that phosphorylated active BTK is significantly higher in UM-CLL. Moreover, UM-CLL, compared to M-CLL, displayed a much higher proliferative capacity that was correlated with higher phospho-BTK and greater sensitivity to ibrutinib. In addition, BTK depletion with siRNA led to a more prominent reduction in the proliferation of UM-CLL, suggesting that elevated BTK activity is responsible for increased cell proliferation. Further, cell signaling activity by multiple measurements was consistently higher in UM-CLL accompanied by a higher sensitivity to ibrutinib. These studies link UM-CLL to elevated BCR signaling, heightened BTK-dependent cell proliferation and increased sensitivity to ibrutinib. The prognostic significance of IGHV mutation should be reevaluated in the era of new therapies targeting BCR signaling.

Identification of a structurally novel BTK mutation that drives ibrutinib resistance in CLL

Ibrutinib (ibr), a first-in-class Bruton tyrosine kinase (BTK) inhibitor, has demonstrated high response rates in both relapsed/refractory and treatment naïve chronic lymphocytic leukemia (CLL). However, about 25% of patients discontinue ibrutinib therapy at a median follow-up of 20 months and many patients discontinue the treatment due to leukemia progression or Richter transformation. Mutations affecting the C481 residue of BTK disrupt ibrutinib binding and have been characterized by us and others as the most common mechanism of ibrutinib resistance. Thus far, all described BTK mutations are located in its kinase domain and mutations outside this domain have never been described. Herein, we report a patient whose CLL progressed, was salvaged with ibrutinib and then relapsed. Serial analysis of samples throughout patients clinical course identified a structurally novel mutation (BTKT316A) in the SH2 domain, but not kinase domain, of Bruton tyrosine kinase which was associated with disease relapse. Functionally, cells carrying BTKT316A show resistance to ibrutinib at both cellular and molecular levels to a similar extent as BTKC481S. Our study lends further insight into the diverse mechanisms of ibrutinib resistance that has important implications for the development of next-generation BTK inhibitors as well as mutation detection in relapsed patients.

Clonal evolution underlying leukemia progression and Richter transformation in patients with ibrutinib-relapsed CLL

Ibrutinib has generated remarkable responses in patients with chronic lymphocytic leukemia (CLL), including those with an unfavorable cytogenetic profile. However, patients develop resistance, with poor outcomes and no established treatment options. Mutations in BTK and PLCG2 have emerged as main mechanisms of drug resistance, but not all patients carry these mutations. Further understanding of mechanisms of resistance is urgently needed and will support rational development of new therapeutic strategies. To that end, we characterized the genomic profiles of serial samples from 9 patients with ibrutinib-relapsed disease, including 6 who had Richter transformation. Mutations, indels, copy-number aberrations, and loss of heterozygosity were assessed using next-generation sequencing and single-nucleotide polymorphism array. We found that 18p deletion (del(18p)), together with del(17p)/TP53 mutations, was present in 5 of 9 patients before ibrutinib therapy. In addition to BTKC481 , we identified BTKT316A , a structurally novel mutation located in the SH2 domain of BTK. Minor BTK clones with low allele frequencies were captured in addition to major BTK clones. Although TP53 loss predisposes patients for relapse, clone size of TP53 loss may diminish during disease progression while mutant BTK clone expands. In patients who had Richter transformation, we found that the transformed cells were clonal descendants of circulating leukemia cells but continued to undergo evolution and drifts. Surprisingly, transformed lymphoma cells in tissue may acquire a different BTK mutation from that in the CLL leukemia cells. Collectively, these results provide insights into clonal evolution underlying ibrutinib relapse and prompt further investigation on genomic abnormalities that have clinical application potential.

Emerging role of checkpoint blockade therapy in lymphoma

Following the successful application of immune checkpoint blockade therapy (CBT) in refractory solid tumors, it has recently gained momentum as a promising modality in the treatment of relapsed lymphoma. This significant therapeutic advance stems from decades of research that elucidated the role of immune regulation pathways and the mechanisms by which tumors can engage these critical pathways to escape immune detection. To date, two main pathways, the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD-1), have emerged as key targets of CBT demonstrating unprecedented activity particularly in heavily pretreated relapsed/refractory Hodgkin lymphoma and some forms of non-Hodgkin disease. Herein we provide a brief discussion of checkpoint blockade in the context of lymphoma biology with a specific focus on novel checkpoint inhibitors and their therapeutic activity. We discuss current clinical trials and the landscape of CBT to underscore both the remarkable progress and foreseeable limitations of this novel treatment strategy. In particular, we build upon state-of-the-art knowledge and clinical insights gained from the early trials to review potential approaches to how CBT may be integrated with other treatment modalities, including chemoimmunotherapy to improve patient outcomes in the future. Finally, as the role of CBT evolves to potentially become a cornerstone of therapy in refractory/relapsed lymphoma, we briefly emphasize the importance of predictive biomarkers in an effort to select appropriate patients who are most likely to derive benefit from CBT.

Analysis of racial variations in disease characteristics, treatment patterns, and outcomes of patients with chronic lymphocytic leukemia.

The impact of race on outcomes of patients with chronic lymphocytic leukemia (CLL), the most common leukemia in the west, is not well studied. We aimed to understand racial variations in clinical and disease characteristics, treatment patterns, and outcomes in patients with CLL. We utilized the Mayo Clinic CLL database to perform an analysis of these characteristics and natural history of non‐white (NW) compared to white (W) CLL patients. Differences by race in median overall survival (OS) and time‐to‐first‐treatment (TTFT) were investigated. Of the 4215 CLL patients, 4114 (97.6%) were W and 101 (2.4%) were NW. NW patients were younger (median age at diagnosis 59.4 vs. 63.4; P = 0.003) and more likely to have an elevated LDH (28.0% vs. 16.2%; P = 0.02). No differences in prognostic parameters were noted. No major differences were observed in treatment selection. OS and TTFT were similar between both groups. In the largest analysis of NW‐CLL patients in North America, and contrary to historical retrospective reports, W and NW patients appear to have comparable outcomes when treated similarly. These findings suggest previously noted outcome differences may be due to disparities in access to care and management rather than differences in disease biology. Am. J. Hematol. 91:677–680, 2016.

The evolving role of lenalidomide in non-Hodgkin lymphoma

Abstract Recent advances in the treatment of patients with non-Hodgkin lymphoma have driven a paradigm shift from standard chemotherapy to an ever-expanding choice of targeted agents and combinations. As an orally bioavailable immunomodulator with antineoplastic, immunologic, and antiproliferative activity in B-cell lymphoma, lenalidomide has emerged as one such option. Lenalidomide demonstrates clinically significant activity with a favorable safety profile as a single agent, as well as in combination therapy. Herein, we review accumulated clinical data on lenalidomide, with particular reference to patients with first-line and relapsed/refractory mantle cell lymphoma, indolent lymphoma, and diffuse large B-cell lymphoma.

Ofatumumab monotherapy in relapsed/refractory diffuse large B-cell non-Hodgkin lymphoma

Despite recent advances, management of relapsed and/or refractory diffuse large B-cell lymphoma (DLBCL) remains a clinical challenge. While hematopoietic stem cell transplantation (HSCT) provides the minority of relapsed patients in the rituximab-era with cure, patients who are transplantation-ineligible and those who relapse after transplantation have few palliative therapeutic choices and represent an unmet medical need.[1] Ofatumumab is a fully humanized monoclonal IgG1k antibody that targets a distinct CD20 epitope.[2] Specifically, by binding to the cell membrane, ofatumumab induces a potent complement-dependent cytotoxicity leading to enhanced cell killing and apoptosis. In preclinical studies, ofatumumab induced apoptosis in rituximab-resistant non-Hodgkin lymphoma (NHL) cell lines.[3] Also, Coiffier et al. administered ofatumumab weekly over 8 weeks in relapsed/ refractory (R/R) DLBCL, reporting an overall response rate (ORR) of 13% in transplant-ineligible patients and 9% in patients who relapsed after transplantation.[4] Ofatumumab was well tolerated with toxicities mostly limited to infusion-related reactions and immunosuppression. Given the favorable side effect profile and a previously established activity of ofatumumab in R/R DLBCL patients, we hypothesized that extended treatment with ofatumumab in transplantation-ineligible patients may lead to improved responses and to an extended clinical benefit. We conducted a phase II study for patients with R/R DLBCL. Eligible patients received ofatumumab 1000 mg weekly for 8 weeks. Patients achieving stable disease or better continued on a maintenance phase of ofatumumab given at 1000 mg every 2 weeks until progression or unacceptable toxicity. All patients had measurable disease and adequate organ function. Patients with central nervous system involvement or known HIV positivity were excluded. One cycle was equivalent to 4 weeks of therapy and response assessment was performed every 8 weeks.[5] The efficacy analysis was done based on a stage II Simon design. Initially, 9 patients were to be enrolled. If 2 out of 9 (20%) patients responded, the study was to continue until a total of 29 patients were treated. This would have allowed an 80% power to confirm an ORR of 20% with an alpha of 0.05. However, due to slow accrual, the study was closed early after 11 patients were enrolled. Between April 2010 and February 2013, 11 patients were enrolled prior to study closure (Table 1). Last DLBCL treatment for all patients was given less than 2 months from enrollment. Median age was 67 years (range 41–89) and all patients had advanced stage disease. All patients were heavily pretreated with a median of 4 prior therapies (range 1–7). Ten patients had disease that was rituximab-containing regimens-refractory and 9 received at least two prior rituximab-based therapies. Four (36%) of the patients previously received a stem cell transplant (2 had an autologous transplant, 1 had an allogeneic, and 1 both). Cell of origin data and whether patients had Germinal or non-Germinal center type DLBCL were not available. None of the patients had transformed disease. All 11 patients completed induction therapy with 8 weekly doses of ofatumumab and were evaluable for response. At the completion of induction, 2 patients achieved a partial response and 2 patients had stable disease, while 7 progressed for an ORR of 18% and a clinical benefit rate of 36%. Five patients went on to receive ofatumumab maintenance for a median duration of 4 cycles (range 1–18). One patient with PD received maintenance ofatumumab inadvertently. Subsequent therapies for progressing patients included bendamustine and rituximab in 2 patients, single agent bendamustine in 1, and investigational therapies in 4 patients. At a median follow-up of 38 months (range 14–48), median PFS was 2 months (range 1–11) and median OS was 7 months (range 1–40). While emerging data on treating DLBCL suggest that cell of origin have an impact on treatment selection,[6] the small number of enrolled patients and lack of this information in our cohort precluded such analysis. Ofatumumab was well tolerated with 3 patients (27%) developing grade

Frequency, risk factors, and outcomes of central nervous system relapse in lymphoma patients treated with dose-adjusted EPOCH plus rituximab

Central nervous system (CNS) relapse in non‐Hodgkin lymphoma (NHL) is a rare but serious complication that carries a poor prognosis. The use of infusional etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (EPOCH‐R) for frontline treatment of diffuse large B cell lymphoma (DLBCL) is increasing, though little is known about incidence of and risk factors for CNS relapse with this regimen

Successful implementation of genomically based treatment of chemotherapy refractory peripheral T-cell lymphoma (PTCL)

ABSTRACT Background: The treatment of peripheral T-cell lymphoma (PTCL) after failure of standard therapy represents a significant clinical challenge as the best approach has not been defined. The outcomes of patients with peripheral T-cell lymphoma (PTCL) after relapse, in the absence of hematopoietic stem-cell transplantation, are poor with median overall survival is less than six months. Thus, relapsed/refractory PTCL presents an area of unmet medical need. Case presentation: Herein, we report an 84-year old woman with stage IV PTCL with extensive involvement of the bowel and abdominal pain. She was treated with cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy which was complicated by prolonged pancytopenia, without response. Disease progression was manifested by small bowel obstruction, for which she received palliative radiation therapy, further complicated by cardiac arrhythmia and sepsis. In the meantime, clinical-grade next generation sequencing of a lymph node (406 gene panel) showed six genomic alterations: NRAS Q61R, PTEN Q17*, CREBBP R768*, EP300 R1529*, SETD2 loss exons 19–21, along with an intermediate tumor mutational burden. Tissue PD-L1 staining was low positive by immunohistochemistry. The patient was discussed in Molecular Tumor Board with consensus opinion favoring a combination of the MEK inhibitor trametinib (for the NRAS alteration) and the checkpoint inhibitor nivolumab for the elevated mutational burden and PD-L1 positivity. Her abdominal pain resolved and she achieved a complete remission ongoing at 5+ months. Side effects at five months included only low-grade rash and peripheral edema. Conclusions: Our observations suggest that matching patients with hematologic malignancies with customized combinations based on genomic sequencing warrants further study as a way to achieve and/or deepen responses, including in patients who are elderly and/or have refractory disease and significant disease-related complications.

University of Chicago phase II consortium trial of selumetinib (MEKi) demonstrates low tolerability and efficacy in relapsed DLBCL

John W. Semple Keenan Research Centre for Biomedical Science of St. Michaels Hospital; Departments of Medicine and Pathology, University of Rochester School of Medicine, Rochester, NY, USA; Canadian Blood Services; Departments of Physiology and Anesthesia, University of Toronto; Department of Anesthesia and Pain Medicine, Hospital for Sick Children; Department of Pharmacology, University of Toronto; Department of Medicine, University of Toronto; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada and Division of Haematology and Transfusion Medicine, Lund University, Lund, Sweden E-mail: john_w.semple@med.lu.se