Safety and efficacy of tenalisib in combination with romidepsin in patients with relapsed/refractory T-cell lymphoma: results from a phase I/II open-label multicenter study.

Tenalisib, a selective phosphoinositide-3-kinase δ/γ, and salt-inducible-kinase-3 inhibitor has shown efficacy and was well-tolerated in patients with T-cell lymphoma (TCL). In vitro studies suggest a synergistic anti-tumor potential for the combination of tenalisib with the histone-deacetylase inhibitor, romidepsin. This multicenter, open-label, phase I/II study was designed to characterize the safety, efficacy and pharmacokinetics of oral tenalisib twice-daily and intravenous romidepsin administered on days 1, 8 and 15 in 28-day cycles in adults with relapsed/refractory TCL. Phase I/dose escalation determined the maximum tolerated dose (MTD)/optimal doses of tenalisib and romidepsin. The phase II/dose expansion assessed the safety and anti-tumor activity of the combination at MTD/optimal dose. Overall, 33 patients were enrolled. In dose escalation, no dose-limiting toxicity was identified. Hence, the recommended doses for dose expansion were tenalisib 800 mg twice daily orally, and romidepsin 14 mg/m2 intravenous. Overall treatment-emergent adverse events of any grade reported in >15% of patients were nausea, thrombocytopenia, increased aspartate aminotransferase, increased alanine aminotransferase, decreased appetite, neutropenia, vomiting, fatigue, anemia, dysgeusia, weight loss, diarrhea, and hypokalemia. Twenty-three patients (69.7%) had related grade ≥3 treatment-emergent adverse events. The overall objective response rate in evaluable patients was 63.0% (peripheral TCL: 75% and cutaneous TCL: 53.3%), with a complete response and partial response of 25.9% and 37.0% respectively. The median duration of response was 5.03 months. Co-administration of tenalisib and romidepsin did not significantly alter the pharmacokinetics of romidepsin. Overall, tenalisib and romidepsin combination demonstrated a favorable safety and efficacy profile supporting its further development for relapsed/refractory TCL (clinicaltrials gov. Identifier: NCT03770000).

Long-term Outcomes After Hematopoietic Cell Transplant in Peripheral T-Cell Lymphoma - The Oregon Health and Science University Experience.

BACKGROUND: Peripheral T-cell lymphomas (PTCL) are a group of aggressive malignancies with inferior outcomes compared to B-cell non-Hodgkin lymphoma (NHL). Both allogeneic and autologous hematopoietic cell transplantation (HCT) are commonly employed for consolidation and salvage. MATERIALS AND METHODS: We conducted a single-center review of all adult PTCL patients at OHSU who received HCT from 1991 to 2020 with responses assed by CIBMTR criteria. RESULTS: 88 patients (autoHCT = 52, alloHCT = 36) were identified from the internal registry of ∼3800 autoHCT & alloHCT recipients in that time period. Median OS after autoHCT and alloHCT were 7.0 and 2.6 years. Median PFS after autoHCT and alloHCT was 3.9 vs 1.1 years. Post-HCT median OS for ALCL, AITL, and PTCL NOS were 14.9, 3.9, and 3.4 years, respectively. Median PFS after autoHCT performed while in CR vs. not in CR was 3.4 vs 4.2 years (P = 0.86); for alloHCT in CR vs. not CR 2.4 vs 0.7 years (P = 0.28). 1-year non-relapse mortality (NRM) for autoHCT and alloHCT were 6.1% and 22.2% (P = 0.2). 10/88 patients developed secondary malignancies including 4 skin cancers, 3 new lymphomas, and 2 MDS. CONCLUSION: Our experience with HCT for PTCL shows that HCT has acceptable toxicities and relatively long disease remissions. AutoHCT was most frequently utilized as planned remission consolidation while alloHCT was most often used late during salvage. Differences in response between autoHCT and alloHCT likely reflect differences in clinical setting and underlying disease natural history and biology.

Patient-Specific Targeting of the T-Cell Receptor Variable Region as a Therapeutic Strategy in Clonal T-Cell Diseases.

PURPOSE: Targeted therapeutics are a goal of medicine. Methods for targeting T-cell lymphoma lack specificity for the malignant cell, leading to elimination of healthy cells. The T-cell receptor (TCR) is designed for antigen recognition. T-cell malignancies expand from a single clone that expresses one of 48 TCR variable beta (Vß) genes, providing a distinct therapeutic target. We hypothesized that a mAb that is exclusive to a specific Vß would eliminate the malignant clone while having minimal effects on healthy T cells. EXPERIMENTAL DESIGN: We identified a patient with large granular T-cell leukemia and sequenced his circulating T-cell population, 95% of which expressed Vß13.3. We developed a panel of anti-Vß13.3 antibodies to test for binding and elimination of the malignant T-cell clone. RESULTS: Therapeutic antibody candidates bound the malignant clone with high affinity. Antibodies killed engineered cell lines expressing the patient TCR Vß13.3 by antibody-dependent cellular cytotoxicity and TCR-mediated activation-induced cell death, and exhibited specific killing of patient malignant T cells in combination with exogenous natural killer cells. EL4 cells expressing the patient's TCR Vß13.3 were also killed by antibody administration in an in vivo murine model. CONCLUSIONS: This approach serves as an outline for development of therapeutics that can treat clonal T-cell-based malignancies and potentially other T-cell-mediated diseases. See related commentary by Varma and Diefenbach, p. 4024.

Phase 1/2 study of intratumoral G100 (TLR4 agonist) with or without pembrolizumab in follicular lymphoma.

Intratumoral injection of G100, a toll-like receptor 4 (TLR4) agonist, was shown pre-clinically to stimulate anti-tumor immune responses and tumor regression. This open-label, multicenter, phase 1/2 trial evaluated the safety, tolerability, and preliminary efficacy of intratumoral G100 injections following localized low-dose radiation in patients with follicular lymphoma (ClinicalTrials.gov #NCT02501473). The study was comprised of a G100 dose escalation (5 or 10 µg/dose, or 20 µg/dose for large tumors); a randomized component comparing G100 to G100 plus pembrolizumab; and G100 20 µg/dose expansion. Adverse events grade ≥3 were uncommon in patients treated with G100, and no unexpected toxicities were observed when combined with pembrolizumab. G100 20 µg (n = 18) resulted in an overall response rate of 33.3% and abscopal tumor regression in 72.2% of patients. This early-phase study provides a foundation for combining an intratumoral TLR4 agonist with agents to produce immune-mediated responses in follicular lymphoma with limited added toxicity.

A novel somatic PLCG2 variant associated with resistance to BTK and SYK inhibition in chronic lymphocytic leukemia.

The treatment of chronic lymphocytic leukemia (CLL) has been transformed by the use of targeted small molecules inhibiting components of the B cell receptor (BCR) signaling pathway (Haematologica, 103, 2018 and e204; Curr Hematol Malig Rep, 14, 2019, 302). Chief among these is ibrutinib, an irreversible inhibitor of Bruton tyrosine kinase (BTK), which produces deep, durable responses in CLL with good tolerability (Haematologica, 103, 2018 and e204). Though prolonged exposure to the drug can exert selective pressure on CLL cells and allow for the emergence of drug-resistant clones, primary ibrutinib treatment failure is rare (Expert Rev Hematol, 11 and 2018, 185; N Engl J Med, 370, 2014 and 2352; N Engl J Med, 373, 2015 and 25, 2425; Blood, 128, 2016 and 2199). Activating mutations in the gene PLCG2, which encodes a downstream target of BTK, appear to enable constitutive BCR signaling and have been associated with ibrutinib resistance (Int J Cancer, 146 and 2020, 85; J Clin Oncol, 35, 2017 and 1437; Blood, 126, 2015 and 61). In recent years, novel investigational agents have targeted other components of the BCR pathway. Among these is entospletinib, an orally bioavailable, selective inhibitor of splenic tyrosine kinase (SYK) (Blood, 126, 2015 and 1744), which lies upstream of the enzyme phospholipase C-gamma-2 (PLCG2). Here, we describe a patient who was found to harbor a novel somatic variant of PLCG2 and experienced a lack of treatment response to both ibrutinib and entospletinib.

Primary cutaneous Epstein-Barr virus-positive diffuse large B-cell lymphoma (DLBCL) in a patient taking fingolimod.

A 55-year-old man with relapsing-remitting multiple sclerosis on fingolimod presented to the dermatology clinic with skin lesions on the left temple and cheek. Histopathology showed a diffuse infiltrate of enlarged, atypical lymphocytes throughout the dermis with an overlying grenz zone and a subpopulation of scattered smaller lymphocytes and plasma cells. Epstein-Barr virus-encoded RNA in situ hybridization stain was positive. Based on the morphologic and immunophenotypic findings, a diagnosis of EBV-positive diffuse large B-cell lymphoma was made. This case aims to raise awareness for the dermatologist that patients on fingolimod may be at increased risk of lymphoproliferative disorders.

Cyclin-Dependent Kinase-9 Is a Therapeutic Target in MYC-Expressing Diffuse Large B-Cell Lymphoma.

Deregulation of the MYC transcription factor is a key driver in lymphomagenesis. MYC induces global changes in gene expression that contribute to cell growth, proliferation, and oncogenesis by stimulating the activity of RNA polymerases. A key feature in its ability to stimulate RNA Pol II activity is recruitment of pTEFb, an elongation factor whose catalytic core comprises CDK9/cyclin T complexes. Hence, MYC expression and function may be susceptible to CDK9 inhibition. We conducted a pre-clinical assessment of AZ5576, a selective CDK9 inhibitor, in diffuse large B-cell lymphoma (DLBCL). The in vitro and in vivo effects of AZ5576 on apoptosis, cell cycle, Mcl-1, and MYC expression were assessed by flow cytometry, immunoblotting, qPCR and RNA-Seq. We demonstrate that, in addition to depleting Mcl-1, targeting CDK9 disrupts MYC oncogenic function. Treatment with AZ5576 inhibited growth of DLBCL cell lines in vitro and in vivo, independent of cell-of-origin. CDK9 inhibition downregulated Mcl-1 and MYC mRNA transcript and protein in a dose-dependent manner. MYC-expressing cell lines demonstrated enhanced susceptibility to AZ5576. CDK9 inhibition promoted turnover of MYC protein, and decreased MYC phosphorylation at the stabilizing Ser62 residue and downregulated MYC transcriptional targets in DLBCL cells, a finding confirmed in a functional reporter assay, suggesting that CDK9 may govern MYC protein turnover, thus regulating its expression through multiple mechanisms. Our data suggest that targeting CDK9 is poised to disrupt MYC oncogenic activity in DLBCL and provide rationale for clinical development of selective CDK9 inhibitors.

Targeting CD47 in Sézary syndrome with SIRPαFc.

Sézary syndrome (SS), the leukemic variant of cutaneous T-cell lymphoma, has limited treatment options and rare occurrences of long-term remission, thus warranting research into new treatment approaches. CD47 has emerged as a promising target for multiple tumor types, but its role in SS remains unknown. Here, we show that CD47 is highly expressed on Sézary cells in the peripheral blood and skin, and the high level of CD47 expression correlates with worse overall survival (OS) in patients with SS. We also demonstrate that CD47 expression on Sézary cells is under the influence of interleukin 4 (IL-4), IL-7, and IL-13. Signal regulatory protein αFc (SIRPαFc; TTI-621), a novel CD47 decoy receptor, triggers macrophage-mediated phagocytosis of Sézary cells and, when administered in clinical trial settings, results in significant tumor load reduction. We conclude that inhibition of the CD47-SIRPα signaling pathway has therapeutic benefit for patients with SS. This trial was registered at www.clinicaltrials.gov as #NCT02663518.

Targeting ubiquitin-activating enzyme induces ER stress-mediated apoptosis in B-cell lymphoma cells.

Alterations in the ubiquitin proteasome system (UPS) leave malignant cells in heightened cellular stress, making them susceptible to proteasome inhibition. However, given the limited efficacy of proteasome inhibitors in non-Hodgkin lymphoma (NHL), novel approaches to target the UPS are needed. Here, we show that TAK-243, the first small-molecule inhibitor of the ubiquitin activating enzyme (UAE) to enter clinical development, disrupts all ubiquitin signaling and global protein ubiquitination in diffuse large B-cell lymphoma (DLBCL) cells, thereby inducing endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Activation of the ER stress response protein kinase R (PKR)-like ER kinase and phosphorylation of eukaryotic translation initiator factor 2α led to upregulation of the proapoptotic molecule C/EBP homologous protein and cell death across a panel of DLBCL cell lines independent of cell of origin. Concurrently, targeting UAE led to accumulation of Cdt1, a replication licensing factor, leading to DNA rereplication, checkpoint activation, and cell cycle arrest. MYC oncoprotein sensitized DLBCL cells to UAE inhibition; engineered expression of MYC enhanced while genetic MYC knockdown protected from TAK-243-induced apoptosis. UAE inhibition demonstrated enhanced ER stress and UPR and increased potency compared with bortezomib in DLBCL cell lines. In vivo treatment with TAK-243 restricted the growth of xenografted DLBCL tumors, accompanied by reduced cell proliferation and apoptosis. Finally, primary patient-derived DLBCL cells, including those expressing aberrant MYC, demonstrated susceptibility to UAE inhibition. In sum, targeting UAE may hold promise as a novel therapeutic approach in NHL.

Colorectal Lymphoma: A Review.

Non-Hodgkin lymphoma (NHL) that primarily involves the colon is rare and should be distinguished from the more common systemic nodal lymphoma. It has unique clinical expectations and management consideration. Different histologic subtypes of NHL involve the colon, which varies in the clinical behavior and likelihood of obtaining durable remissions with treatment. This article will review the current understanding of the different histologic subtypes of primary colorectal lymphoma and propose management algorithms.

Outcomes of DA-EPOCH-R induction plus autologous transplant consolidation for double hit lymphoma.

High-grade B cell lymphoma with MYC and BCL2 rearrangements (double hit) has a poor prognosis with standard R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). We report here a treatment algorithm of DA-EPOCH-R (dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, rituximab) followed by BEAM (carmustine, etoposide, cytarabine, melphalan) autologous transplant in 36 cases of previously untreated double hit lymphoma (DHL) from 2010 to 2015. A high risk International Prognostic Index (IPI) was present in 42% of cases. At median follow-up of 38 months, the 2-year progression free survival (PFS) and overall survival (OS) were 69% (95% CI 54-84%) and 71% (95% CI 56-86%). Eight cases were refractory to induction with 1-year OS 20%, and no factors were predictive for primary refractory disease. Of 28 responders, 17 proceeded to transplant while 11 were observed, primarily due to age and co-morbidities. By 24-week landmark analysis after diagnosis, the 2-year PFS and OS were both 94% (95% CI 83-100%) vs 79% (95% CI 52-100%) for transplant vs observation (p = .59 for both PFS and OS). There was no significant benefit to consolidative transplant in our series, and primary refractory DHL needs novel approaches.

Targeting the programmed cell death 1 pathway in Hodgkin lymphoma: the place of nivolumab.

Nivolumab is a humanized immunoglobulin gamma-4 kappa anti-programmed cell death 1 monoclonal antibody that is currently approved in the treatment of several solid tumors and recently gained accelerated approval in classical Hodgkin lymphoma (cHL) that has relapsed or progressed following autologous hematopoietic stem-cell transplantation and post-transplantation brentuximab vedotin. The purpose of this article is to review the immunophysiologic basis, clinical efficacy, and toxicity of nivolumab in the treatment of cHL. In addition, we will review ongoing clinical trials and potential future directions of checkpoint inhibition in the treatment of cHL.

Diffuse large B-cell lymphoma in adults aged 75 years and older: a single institution analysis of cause-specific survival and prognostic factors.

BACKGROUND: Very elderly patients (75 years and older) with diffuse large B-cell lymphoma (DLBCL) will be increasingly considered for cancer treatment as the population ages, but are underrepresented in clinical trials. Here we report outcomes of very elderly DLBCL patients treated in the modern era at the Oregon Health and Science University (OHSU). METHODS: We queried the OHSU Tumor Registry for DLBCL cases treated since 2002. A total of 73 patients aged 75 years or older were analyzed under Institutional Review Board approval. RESULTS: With a median follow up of 31 months, cause-specific survival was 58% and overall survival 51% at 3 years. Incorporation of an anthracycline did not influence outcomes. More than one extranodal site or poor-risk disease by Revised International Prognostic Index score were adversely prognostic, but pathologic features studied were not. CONCLUSIONS: Very elderly patients with DLBCL require prospective studies, which employ novel risk stratification and therapeutic approaches.

Cladribine plus rituximab is an effective therapy for newly diagnosed mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a non-Hodgkin lymphoma that is incurable with standard chemotherapy. There is no consensus on the best initial therapy, especially for elderly patients, who are not candidates for aggressive treatment approaches. Current National Comprehensive Cancer Network (NCCN) treatment guidelines include rituximab (R) plus cladribine for the initial treatment of MCL. However, few data are available to substantiate this recommendation. Therefore, to further define the role of R-cladribine for the initial treatment of MCL, we performed a retrospective chart review of 31 patients with MCL (median age, 67) treated with R-cladribine. The majority of responding patients also received R maintenance. The overall response rate was 87%, with 61% of patients achieving a complete remission (CR/CRu). The estimated median follow-up was 32.5 months, median PFS was 37.5 months, and median OS was 85.2 months. One of 19 (5.3%) subjects in CR/CRu relapsed (median follow-up of 23 months). CR/CRu was associated with improved survival (p < 0.0001), while a high mantle cell international prognostic index (MIPI) was associated with worse survival (p = 0.05). There was one toxic death (neutropenic pseudomonal sepsis) related to treatment. R-cladribine is an effective therapy for previously untreated MCL, and these results validate the use of R-cladribine for the initial treatment of MCL.

Gene expression and angiotropism in primary CNS lymphoma.

Primary CNS lymphoma is an aggressive form of non-Hodgkin lymphoma whose growth is restricted to the central nervous system. We used cDNA microarray analysis to compare the gene expression signature of primary CNS lymphomas with nodal large B-cell lymphomas. Here, we show that while individual cases of primary CNS lymphomas may be classified as germinal center B-cell, activated B-cell, or type 3 large B-cell lymphoma, brain lymphomas are distinguished from nodal large B-cell lymphomas by high expression of regulators of the unfolded protein response (UPR) signaling pathway, by the oncogenes c-Myc and Pim-1, and by distinct regulators of apoptosis. We demonstrate that interleukin-4 (IL-4) is expressed by tumor vasculature as well as by tumor cells in CNS lymphomas. We also identify high expression in CNS lymphomas of several IL-4-induced genes, including X-box binding protein 1 (XBP-1), a regulator of the UPR. In addition, we demonstrate expression of the activated form of STAT6, a mediator of IL-4 signaling, by tumor cells and tumor endothelia in CNS lymphomas. High expression of activated STAT6 in tumors was associated with short survival in an independent set of patients with primary CNS lymphoma who were treated with high-dose intravenous methotrexate therapy.

Adjuvant IL-15 does not enhance the efficacy of tumor cell lysate-pulsed dendritic cell vaccines for active immunotherapy of T cell lymphoma.

There has been a recent interest in using IL-15 to enhance antitumor activity in several models because of its ability to stimulate CD8+ T cell expansion, inhibit apoptosis and promote memory T cell survival and maintenance. Previously, we reported that C6VL tumor lysate-pulsed dendritic cell vaccines significantly enhanced the survival of tumor-bearing mice by stimulating a potent tumor-specific CD8+ T cell response. In this study, we determined whether IL-15 used as immunologic adjuvant would augment vaccine-primed CD8+ T cell immunity against C6VL and further improve the survival of tumor-bearing mice. We report that IL-15 given after C6VL lysate-pulsed dendritic cell vaccines stimulated local and systemic expansion of NK, NKT and CD8+ CD44hi T cells. IL-15 did not, however, augment innate or cellular responses against the tumor. T cells from mice infused with IL-15 following vaccination did not secrete increased levels of tumor-specific TNF-alpha or IFN-gamma or have enhanced C6VL-specific CTL activity compared to T cells from recipients of the vaccine alone. Lastly, IL-15 did not enhance the survival of tumor-bearing vaccinated mice. Thus, while activated- and memory-phenotype CD8+ T cells were dramatically expanded by IL-15 infusion, vaccine-primed CD8+ T cell specific for C6VL were not significantly expanded. This is the first account of using IL-15 as an adjuvant in a therapeutic model of active immunotherapy where there was not a preexisting pool of tumor-specific CD8+ T cells. Our results contrast the recent studies where IL-15 was successfully used to augment tumor-reactivity of adoptively transferred transgenic CD8+ T cells. This suggests that the adjuvant potential of IL-15 may be greatest in settings where it can augment the number and activity of preexisting tumor-specific CD8+ T cells.

Galloping ophthalmoplegia and numb chin in Burkitt lymphoma.

A 57-year-old man developed complete bilateral ophthalmoplegia over a period of 10 days, together with bilateral facial pain and numbness of the chin. He had no other clinical manifestations. Findings on brain magnetic resonance imaging and spinal fluid formula from the first lumbar puncture were normal, but cerebrospinal fluid flow cytometry disclosed a kappa restriction monoclonal B-cell population, indicating malignant lymphoma. Computed tomography of the chest, abdomen, and pelvis then revealed multiple enlarged lymph nodes. Biopsy of an inguinal node showed findings consistent with Burkitt lymphoma. Within six weeks, intravenous and intrathecal chemotherapy resolved all neurologic findings except a partial right-side sixth nerve palsy and mild chin numbness. Eighteen months after disease onset, the patient remained in remission. Meningeal spread of Burkitt lymphoma is not commonly a presenting feature in immunocompetent adults. Chin numbness, a characteristic feature caused by infiltration of the mental nerve, should facilitate earlier recognition, which may be life saving.

TCR vaccines against a murine T cell lymphoma: a primary role for antibodies of the IgG2c class in tumor protection.

Tumor-associated proteins can act as effective immunotherapeutic targets. Immunization with tumor TCR protein conjugated to the immunogenic protein keyhole limpet hemocyanin (KLH) protects mice from tumor challenge with the murine T cell lymphoma C6VL. The immune mechanisms responsible for this tumor protection are of interest for designing more effective vaccine strategies. Previous studies using depletion experiments had suggested a CD8-mediated component of protection induced by TCR-KLH vaccines. In this study we used CD8alpha knockout, micro MT, and FcgammaR knockout mice to investigate the relative roles of CD8+ T cells and Ab in protective immunity induced by TCR-KLH immunization. We found that CD8+ T cells are not required for tumor protection, although they may contribute to protection. Vaccine-induced Abs are sufficient to mediate protection against this murine T cell lymphoma through an FcR-dependent mechanism. This was confirmed with Ab transfers, which protect challenged mice. Additionally, recombinase-activating gene 1(-/-) splenocytes can mediate Ab-dependent cellular cytotoxicity against this tumor in the presence of bound anti-TCR Abs. IFN-gamma knockout mice demonstrated a requirement for IFN-gamma, probably via generation of IgG2c Abs, in vaccine-induced tumor protection. IFN-gamma knockout mice were not protected by immunization and had a severe impairment in IgG2c Ab production in response to immunization. Although mock-depleted anti-TCR Abs could transfer tumor protection, IgG2c-deficient anti-TCR Abs were unable to transfer tumor protection to wild-type mice. These results suggest that TCR-KLH vaccine-induced tumor protection in the C6VL system is primarily attributable to the induction of IgG2c Abs and humoral immunity.