Treatment of Richter's Transformation with Novel Therapies.

PURPOSE OF REVIEW: This review presents recently published clinical trial data and ongoing investigations regarding the treatment of Richter's transformation (RT). RECENT FINDINGS: Recently, numerous approaches have been investigated for the treatment of RT including: traditional chemoimmunotherapy regimens combined with targeted agents such as BTKi and BCL2i; immunotherapy combined with targeted agents; non-covalent BTKis; bispecific T cell engagers; and CART therapy. In addition, various novel targeted agents are currently being studied for the treatment of RT in phase 1 and 2 clinical trials. Standard of care treatment with chemoimmunotherapy for RT has limited efficacy in achieving durable remissions. Here, we review recent data on the use of combination treatments and targeted agents in RT. Although some progress has been made in the investigation to optimize treatment of RT, further study is needed to evaluate long term outcomes of recently published trials and test efficacy of upcoming novel agents.

A validated composite comorbidity index predicts outcomes of CAR T-cell therapy in patients with diffuse large B-cell lymphoma.

Chimeric antigen receptor T-cell therapy (CART) has extended survival of patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL). However, limited durability of response and prevalent toxicities remain problematic. Identifying patients who are at high risk of disease progression, toxicity, and death would inform treatment decisions. Although the cumulative illness rating scale (CIRS) has been shown to correlate with survival in B-cell malignancies, no prognostic score has been independently validated in CART recipients. We retrospectively identified 577 patients with relapsed/refractory DLBCL indicated for CART at 9 academic centers to form a learning cohort (LC). Random survival forest modeling of overall survival (OS) and progression-free survival (PFS) was performed to determine the most influential CIRS organ systems and severity grades. The presence of a severe comorbidity (CIRS score ≥ 3) in the respiratory, upper gastrointestinal, hepatic, or renal system, herein termed "Severe4," had the greatest impact on post-CART survival. Controlling for other prognostic factors (number of prior therapies, Eastern Cooperative Oncology Group performance status, BCL6 translocation, and molecular subtype), Severe4 was strongly associated with shorter PFS and OS in the LC and in an independent single-center validation cohort (VC). Severe4 was also a significant predictor of grade ≥3 cytokine release syndrome in the LC, while maintaining this trend in the VC. Thus, our results indicate that adverse outcomes for patients with DLBCL meant to receive CART can be predicted using a simplified CIRS-derived comorbidity index.

Assessment of Salvage Regimens Post-Chimeric Antigen Receptor T Cell Therapy for Patients with Diffuse Large B Cell Lymphoma.

Anti-CD19 chimeric antigen receptor T cell therapy (CAR19) represents a critical treatment modality for patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). However, the majority of patients subsequently experience disease progression following CAR19, and data are limited on assessing the best salvage regimen for these patients. This study aimed to evaluate outcomes in R/R DLBCL patients with progressive disease post-CAR19 and to assess variables that predict response to salvage therapy. We performed a retrospective analysis of all patients with DLBCL who received CAR19 at our institution between January 2018 and February 2021, collecting data on demographic characteristics, disease characteristics, best response to CAR19, date of relapse or progression, and first salvage therapy and response to salvage. We analyzed patients according to whether they responded to CAR19 (responders) or did not (nonresponders). Salvage regimens were classified into 6 groups for analysis. Primary endpoints included overall survival (OS) and progression-free survival (PFS), calculated using the Kaplan-Meier method. Cox models were fit to evaluate the effect of prognostic factors. Among the 120 patients who received CAR19 during the analysis period were 69 responders who achieved a complete or partial response to CAR19 and 51 nonresponders, including 44 with stable or progressive disease and 7 who died before assessment. Thirty responders relapsed and 26 received salvage therapy, and 24 nonresponders received salvage therapy. The primary salvage regimens included lenalidomide-based regimens (n = 17; 34%), BTKi (n = 10; 20%), checkpoint inhibitor-based (n = 7; 14%), chemo-immunotherapy (n = 5; 10%), allogeneic hematopoietic stem cell transplantation (n = 5; 10%), and others (n = 6; 12%). There was no significant difference in OS based on salvage regimen (P = .4545). Responders who received salvage therapy had significantly longer OS than nonresponders (median OS not reached versus 10.9 months; P = .0187), and response to CAR19 and elevated lactate dehydrogenase level at time of salvage treatment were the only two statistically significant prognostic factors after accounting for other variables. Responders to CAR19 had significantly better outcomes with salvage therapy compared with nonresponders to CAR19. There was no significant difference in outcomes based on salvage regimen. Future research is needed to assess the best salvage regimen post-CAR19 failure.

Cellular Therapy Advances in Chronic Lymphocytic Leukemia and Richter's Syndrome.

Over the past 10 years, there have been great treatment advances for chronic lymphocytic leukemia (CLL) with the development of small molecule inhibitors. However, there remains an area of unmet need for patients who progress on novel therapies. The development of cellular therapies in CLL has been hindered by CLL induced immunosuppression. Fortunately, recent progress in various methods in immunomodulation may help overcome this limitation in CLL. These advances have spurred ongoing interest in the development of cellular therapies for CLL, including chimeric antigen receptor (CAR) T cell therapies, bi-specific antibodies, and use of natural killer cells. These novel treatment modalities may hold promise for patients with refractory, and potentially transformed disease. Here, we discuss the development of CAR-T cell therapy in CLL and the impact of combining CAR-T and small molecule inhibitors on treatment outcomes, the evolving role of bi-specific antibodies and natural killer cells, and comment on the use of cellular therapies for Richter's syndrome.

Redeployment of Myc and E2f1-3 drives Rb-deficient cell cycles.

Robust mechanisms to control cell proliferation have evolved to maintain the integrity of organ architecture. Here, we investigated how two critical proliferative pathways, Myc and E2f, are integrated to control cell cycles in normal and Rb-deficient cells using a murine intestinal model. We show that Myc and E2f1-3 have little impact on normal G1-S transitions. Instead, they synergistically control an S-G2 transcriptional program required for normal cell divisions and maintaining crypt-villus integrity. Surprisingly, Rb deficiency results in the Myc-dependent accumulation of E2f3 protein and chromatin repositioning of both Myc and E2f3, leading to the 'super activation' of a G1-S transcriptional program, ectopic S phase entry and rampant cell proliferation. These findings reveal that Rb-deficient cells hijack and redeploy Myc and E2f3 from an S-G2 program essential for normal cell cycles to a G1-S program that re-engages ectopic cell cycles, exposing an unanticipated addiction of Rb-null cells on Myc.