BET inhibition reforms the immune microenvironment and alleviates T cell dysfunction in chronic lymphocytic leukemia.

Redundant tumor microenvironment (TME) immunosuppressive mechanisms and epigenetic maintenance of terminal T cell exhaustion greatly hinder functional antitumor immune responses in chronic lymphocytic leukemia (CLL). Bromodomain and extraterminal (BET) proteins regulate key pathways contributing to CLL pathogenesis and TME interactions, including T cell function and differentiation. Herein, we report that blocking BET protein function alleviates immunosuppressive networks in the CLL TME and repairs inherent CLL T cell defects. The pan-BET inhibitor OPN-51107 reduced exhaustion-associated cell signatures resulting in improved T cell proliferation and effector function in the Eµ-TCL1 splenic TME. Following BET inhibition (BET-i), TME T cells coexpressed significantly fewer inhibitory receptors (IRs) (e.g., PD-1, CD160, CD244, LAG3, VISTA). Complementary results were witnessed in primary CLL cultures, wherein OPN-51107 exerted proinflammatory effects on T cells, regardless of leukemic cell burden. BET-i additionally promotes a progenitor T cell phenotype through reduced expression of transcription factors that maintain terminal differentiation and increased expression of TCF-1, at least in part through altered chromatin accessibility. Moreover, direct T cell effects of BET-i were unmatched by common targeted therapies in CLL. This study demonstrates the immunomodulatory action of BET-i on CLL T cells and supports the inclusion of BET inhibitors in the management of CLL to alleviate terminal T cell dysfunction and potentially enhance tumoricidal T cell activity.

Novel Spirocyclic Dimer, SpiD3, Targets Chronic Lymphocytic Leukemia Survival Pathways with Potent Preclinical Effects.

Chronic lymphocytic leukemia (CLL) cell survival and growth is fueled by the induction of B-cell receptor (BCR) signaling within the tumor microenvironment (TME) driving activation of NFκB signaling and the unfolded protein response (UPR). Malignant cells have higher basal levels of UPR posing a unique therapeutic window to combat CLL cell growth using pharmacologic agents that induce accumulation of misfolded proteins. Frontline CLL therapeutics that directly target BCR signaling such as Bruton tyrosine kinase (BTK) inhibitors (e.g., ibrutinib) have enhanced patient survival. However, resistance mechanisms wherein tumor cells bypass BTK inhibition through acquired BTK mutations, and/or activation of alternative survival mechanisms have rendered ibrutinib ineffective, imposing the need for novel therapeutics. We evaluated SpiD3, a novel spirocyclic dimer, in CLL cell lines, patient-derived CLL samples, ibrutinib-resistant CLL cells, and in the Eµ-TCL1 mouse model. Our integrated multi-omics and functional analyses revealed BCR signaling, NFκB signaling, and endoplasmic reticulum stress among the top pathways modulated by SpiD3. This was accompanied by marked upregulation of the UPR and inhibition of global protein synthesis in CLL cell lines and patient-derived CLL cells. In ibrutinib-resistant CLL cells, SpiD3 retained its antileukemic effects, mirrored in reduced activation of key proliferative pathways (e.g., PRAS, ERK, MYC). Translationally, we observed reduced tumor burden in SpiD3-treated Eµ-TCL1 mice. Our findings reveal that SpiD3 exploits critical vulnerabilities in CLL cells including NFκB signaling and the UPR, culminating in profound antitumor properties independent of TME stimuli. SIGNIFICANCE: SpiD3 demonstrates cytotoxicity in CLL partially through inhibition of NFκB signaling independent of tumor-supportive stimuli. By inducing the accumulation of unfolded proteins, SpiD3 activates the UPR and hinders protein synthesis in CLL cells. Overall, SpiD3 exploits critical CLL vulnerabilities (i.e., the NFκB pathway and UPR) highlighting its use in drug-resistant CLL.

Diagnostic, Pathologic, and Therapeutic Considerations for Primary CNS Lymphoma.

Primary CNS lymphoma (PCNSL) is a rare lymphoma representing 3% of CNS malignancies. The diagnosis is complicated by the unique risks associated with brain biopsy, and the treatment is similarly complicated by the restriction of effective therapeutics able to cross the blood-brain barrier. Currently, the majority of individuals diagnosed with this disease are immunocompetent although immune deficiency related to HIV or immunosuppressive therapy remains an important risk factor. Improvements in both frontline therapy and consolidation options, including the use of hematopoietic stem-cell transplantation, have translated to improved survival. Unfortunately, patients experiencing relapsed or refractory disease often fare poorly. Here, we review key clinical, pathologic, and therapeutic aspects of PCNSL and highlight challenging clinical scenarios that may be encountered by the treating oncologist.

ALK-positive anaplastic large cell lymphoma in adults.

ALK-positive anaplastic large cell lymphoma (ALCL) represents approximately 6-7% of the mature T-cell lymphomas. This subtype contains a translocation between the ALK gene on chromosome 2 and one of several other genes that together form an oncogene. The most frequent translocation is t(2;5) which combines ALK with NPM1. This lymphoma has a median age of 34 years, is more common in males, and is in advanced stage at the time of diagnosis in most patients. ALK-positive ALCL is the most curable of the peripheral T-cell lymphomas. The CHOP regimen has been most frequently used, but results are improved with the substitution of brentuximab vedotin for vincristine (BV-CHP) and the addition of etoposide (CHOEP), with BV-CHP being favored. Salvage therapies include allogeneic or autologous bone marrow transplantation, BV, if not used as part of the primary therapy, and ALK inhibitors. The latter are very active and likely to be incorporated into the primary therapy.

The shifting roles and toxicities of cellular therapies in B-cell malignancies.

Cellular therapies provide a curative-intent option for patients with relapsedand refractory lymphomas. Current options including high dose chemotherapyfollowed by autologous or allogeneic hematopoietic stem cell transplantation or CD19 chimericantigen receptor T-cell (CART) therapy. The indication varies according to lymphoma sub-type and line oftherapy. The sequencing of these therapies and their use in second-line orlater settings to manage these diseases is undergoing significant changes, withCD19 CAR T becoming a preferred option for relapsed aggressive B-cell lymphoma.The mechanism of both therapies causes significant yet distinctlymphodepletion, infectious, and inflammatory toxicities. The resulting patternand timing of immune reconstitution helps guide risk-mitigating strategies,revaccination, and infectious prophylaxis. In this review, we discuss theindication, efficacy, toxicity and immune reconstitution of autologoushematopoietic stem cell transplantation and CAR T therapy for use in thetreatment of lymphoma.

Defining the Role of the Gut Microbiome in the Pathogenesis and Treatment of Lymphoid Malignancies.

The gut microbiome is increasingly being recognized as an important immunologic environment, with direct links to the host immune system. The scale of the gut microbiome's genomic repertoire extends the capacity of its host's genome by providing additional metabolic output, and the close communication between gut microbiota and mucosal immune cells provides a continued opportunity for immune education. The relationship between the gut microbiome and the host immune system has important implications for oncologic disease, including lymphoma, a malignancy derived from within the immune system itself. In this review, we explore past and recent discoveries describing the role that bacterial populations play in lymphomagenesis, diagnosis, and therapy. We highlight key relationships within the gut microbiome-immune-oncology axis that present exciting opportunities for directed interventions intended to shape the microbiome for therapeutic effect. We conclude with a limited summary of active clinical trials targeting the microbiome in hematologic malignancies, along with future directions on gut microbiome investigations within lymphoid malignancies.

A Novel Triple-Action Inhibitor Targeting B-Cell Receptor Signaling and BRD4 Demonstrates Preclinical Activity in Chronic Lymphocytic Leukemia.

B-cell chronic lymphocytic leukemia (CLL) results from intrinsic genetic defects and complex microenvironment stimuli that fuel CLL cell growth through an array of survival signaling pathways. Novel small-molecule agents targeting the B-cell receptor pathway and anti-apoptotic proteins alone or in combination have revolutionized the management of CLL, yet combination therapy carries significant toxicity and CLL remains incurable due to residual disease and relapse. Single-molecule inhibitors that can target multiple disease-driving factors are thus an attractive approach to combat both drug resistance and combination-therapy-related toxicities. We demonstrate that SRX3305, a novel small-molecule BTK/PI3K/BRD4 inhibitor that targets three distinctive facets of CLL biology, attenuates CLL cell proliferation and promotes apoptosis in a dose-dependent fashion. SRX3305 also inhibits the activation-induced proliferation of primary CLL cells in vitro and effectively blocks microenvironment-mediated survival signals, including stromal cell contact. Furthermore, SRX3305 blocks CLL cell migration toward CXCL-12 and CXCL-13, which are major chemokines involved in CLL cell homing and retention in microenvironment niches. Importantly, SRX3305 maintains its anti-tumor effects in ibrutinib-resistant CLL cells. Collectively, this study establishes the preclinical efficacy of SRX3305 in CLL, providing significant rationale for its development as a therapeutic agent for CLL and related disorders.

Impact of initial chemotherapy regimen on outcomes for patients with double-expressor lymphoma: A multi-center analysis.

Diffuse large B-cell lymphoma featuring overexpression of MYC and B-Cell Lymphoma 2 (double expressor lymphoma, DEL) is associated with poor outcomes. Existing evidence suggesting improved outcomes for DEL with the use of more intensive regimens than R-CHOP is restricted to younger patients and based on limited evidence from low patient numbers. We retrospectively evaluated the impact of intensive frontline regimens versus R-CHOP in a multicenter analysis across 7 academic medical centers in the United States. We collected 90 cases of DEL, 46 out of 90 patients (51%) received R-CHOP and 44/90 (49%) received an intensive regimen, which was predominantly DA-EPOCH-R. Treatment cohorts were evenly balanced for demographics and disease characteristics, though the intensive group had a higher lactate dehydrogenase (LDH, 326 vs. 230 U/L p = 0.06) and presence of B-symptoms (50% vs. 22%, p = 0.01) compared to the R-CHOP cohort. There was no difference in PFS (median 53 vs. 38 months, p = 0.49) or overall survival (67 vs. not reached months, p = 0.14) between the R-CHOP and intensive therapy cohorts, respectively. On multivariate analysis, intensive therapy was associated with a hazard ratio of 2.35 (95% CI 0.74-7.41), though this was not statistically significant. Additionally, a subgroup analysis of intermediate high-risk lymphoma defined by IPI ≥3 did not identify a difference in survival outcomes between regimens. We conclude that in our multi-center cohort there is no evidence supporting the use of intensive regimens over R-CHOP, suggesting that R-CHOP remains the standard of care for treating DEL.

Clinical effects and applications of the gut microbiome in hematologic malignancies.

The gut microbiome and its effects on host immunity have exciting implications for cancer prognosis and therapy. Examples in allogeneic hematopoietic stem cell transplantation (allo-SCT) demonstrate the role of the gut microbiome as a biomarker for clinical outcomes, and animal models demonstrate how microbiota manipulation may augment therapeutic responses. There are multiple mechanisms that gut microbiota may have in affecting distant tumor environments, including control of cytokine release, dendritic cell activation, and T-cell lymphocyte stimulation. Recently, there has been a marked interest in understanding interactions between host and microbiome in hematologic malignancies. This review summarizes the current understanding of the gut microbiome and its impact on leukemia, lymphoma, multiple myeloma, and allo-SCT and highlights several broad methods for targeting the gut microbiome in therapeutic trials.

Diagnostic challenges in an aggressive case of peripheralizing marginal zone lymphoma.

B-cell lymphomas with atypical presentation or immunophenotype pose diagnostic challenges. Conventional ancillary tests (cytogenetics, FISH) can help, but have technical limitations. New technologies such as mate-pair sequencing (MPSeq) offer a route around these technical limitations.

Decitabine induction with myeloablative conditioning and allogeneic hematopoietic stem cell transplantation in high-risk patients with myeloid malignancies is associated with a high rate of infectious complications.

Patients with high-risk myelodysplastic syndrome or acute myeloid leukemia have an increased risk of death following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Decitabine has minimal non-hematologic toxicity and proven efficacy in myeloid diseases, and post-transplant cyclophosphamide (PTCy) has reduced rates of graft-versus-host-disease (GVHD). We hypothesized that decitabine induction with allo-HSCT and PTCy would improve outcomes in a high-risk myeloid disease population. We performed a phase-II trial of decitabine at 20 mg/m2 for 10 days followed by allo-HSCT using a myeloablative regimen of fludarabine, IV busulfan and 4 Gy total body irradiation with PTCy for GVHD prophylaxis. Twenty patients underwent decitabine induction and 17 patients proceeded to transplant per protocol. Median overall survival from decitabine induction was 210 days (95 % CI 122-not reached). All patients developed grade 4 neutropenia after decitabine, eleven patients (55 %) developed grade 3-4 infections, and 5 cases were fatal. There were 5/20 (25 %) long-term survivors with a median follow-up of 3.6 years. Decitabine induction followed by myeloablative allo-HSCT in a high-risk population was associated with a high risk of infection and mortality related to enhanced immunosuppression. Further exploration of decitabine conditioning on reduced intensity platforms and improved infectious prophylaxis and screening may better mitigate toxicity (ClinicalTrials.gov (NCT01707004)).

Characterization of cancer comorbidity prior to allogeneic hematopoietic cell transplantation.

Higher comorbidity by the hematopoietic cell transplantation-comorbidity index increases rates of non-relapse mortality (NRM) and impairs survival following allogeneic hematopoietic transplantation. We explored the effects of cancer as a comorbid condition prior to allogeneic transplantation. Among 356 adult transplant recipients, 54 patients (15%) had 58 comorbid cancers. Among 33 solid cancers (9%), breast (n = 12; 20%) was most common; among 26 comorbid hematologic malignancies (i.e. separate hematologic malignancy not related to primary disease) (7%), lymphoma was most common (n = 14; 24%). In unadjusted analysis, increased risks for NRM were found for cancer comorbidity (HR 2.1, p < .001), solid tumor alone (HR 2.1, p < .001), and hematologic malignancy alone (HR 1.9, p = .03). Cancer comorbidity did not impair 2-year overall survival (HR 1.33, CI 0.92-1.94). Both hematologic and solid cancers likely contribute to elevated risks of nonrelapse mortality, unrelated to recurrence of the cancer comorbidity. Further study is indicated to validate these findings.

Incidence and predictors of respiratory viral infections by multiplex PCR in allogeneic hematopoietic cell transplant recipients 50 years and older including geriatric assessment.

Community respiratory viruses (CRV) are important agents of morbidity and mortality within the allogeneic hematopoietic stem cell transplant (HCT) population. Few proven methods to prevent CRV infections exist. No studies have specifically investigated their impact on older patients. We reviewed patients 50 years and older undergoing HCT between 2009-2013 to determine the incidence of CRV infection using multiplex PCR and risk factors for infection including geriatric assessment (GA). Thirty-two first episode CRV infections occurred in 118 patients for a 1-year cumulative incidence of 27.2% (CI: 19.4-35.6%). Hospitalization and mortality were restricted to those who developed lower respiratory tract infections (LRTI) (n = 22, 69%). CRV infection contributed to 8 deaths (36% of LRTIs) and 7 of these patients were taking steroids for GvHD at the time of infection. Health impairments by GA did not translate into increased risk for CRV infection. Steroid use at time of LRTI was associated with high mortality.