Salvage Therapy With Polatuzumab Vedotin, Bendamustine, and Rituximab Prior to Allogeneic Hematopoietic Transplantation in Patients With Aggressive Lymphomas Relapsing After Therapy With Chimeric Antigen Receptor T-Cells-Report on Two Cases

Meta-analysis of response rates to first-line salvage treatment after CAR-T therapy failure in large B-cell lymphoma patients

INTRODUCTION

The prognosis for large B-cell lymphoma (LBCL) patients who did not respond or relapsed after chimeric antigen receptor (CAR)-T therapy remains dismal, with no established consensus on the most effective salvage regimen.

METHODS

We conducted a random-effects meta-analysis of complete response (CR) and overall response rates (ORR) to first-line treatments for CAR-T-relapsed/refractory LBCL. We followed the predefined protocol available at PROSPERO (CRD42023473854).

RESULTS

We identified 41 studies evaluating the following interventions: non-CD19 CAR-T, CD19 CAR-T, bispecific antibodies (BiTEs), lenalidomide- and polatuzumab-based regimens, radiotherapy, immune checkpoint inhibitors (ICI), Bruton's Tyrosine Kinase inhibitors (BTKi). Non-CD19 CAR-T cells yielded the best CR (56%, CI: 40-71%), significantly higher than other interventions except CD19 CAR-T (CR = 30%, CI: 7-58%). BiTEs, radiotherapy, lenalidomide- and polatuzumab-based regimens (CR: 28%, 26%, 19%, 24% respectively) did not differ significantly from each other. ICI and BTKi showed the lowest CR rates (12%, CI: 5-20% and 8%, CI: 0-23%, respectively), and were also significantly inferior to BiTEs. ORR was the highest for non-CD19 CAR-T (ORR = 80%, CI: 66-92%), whereas all other regimens yielded values below 50%.

CONCLUSIONS

Non-CD19 CAR-T cells were associated with higher response rates and should be considered if patients are eligible. Given the heterogeneity of the estimates, the results should be interpreted cautiously.

REGISTRATION

PROSPERO CRD42023473854.

A multicenter retrospective study of polatuzumab vedotin in patients with large B-cell lymphoma after CAR T-cell therapy

Polatuzumab vedotin (PV) is an antibody-drug conjugate targeting CD79b that is approved for patients with relapsed/refractory large B-cell lymphoma (LBCL). Patients who relapse after chimeric antigen receptor (CAR) T-cell therapy were not included in the registration study, and reports of PV use after CAR T cells are limited. This multicenter retrospective analysis included patients with LBCL who relapsed or progressed after CAR T-cell therapy and subsequently received PV with or without rituximab and bendamustine between July 2019 and May 2021. Response to treatment and progression were assessed based on the 2014 Lugano criteria. Fifty-seven patients were included in the study: 18 (32%) patients were primary refractory to CAR T-cell therapy, and 34 (60%) patients received PV-based therapy immediately after CAR T-cell therapy. PV was combined with rituximab in 54 (95%) patients and administered with bendamustine in 35 (61%) patients. A response was achieved in 25 (44%) patients, including complete remission in 8 (14%). No significant association between baseline characteristics and response was observed. After a median follow-up of 47 weeks (95% confidence interval [CI], 40-54), 46 (81%) patients had disease progression or died, and the median progression-free survival was 10 weeks (95% CI, 5-15). On a multivariate analysis, bone marrow involvement (hazard ratio, 5.2; 95% CI, 1.8-15; P = .003) and elevated lactate dehydrogenase levels (hazard ratio, 5.0; 95% CI, 1.4-16; P = .01) were associated with shorter progression-free survival. Studies aimed at better characterizing the intrinsic mechanism of resistance and identifying optimal consolidation strategies for these patients are warranted.