Overall Survival Following First and Second Relapse of DLBCL Treated with Therapies Including Autologous Transplant and CAR-T Cells: Results from the Lion Prospective Observational Registry

Background: Diffuse large B cell lymphoma (DLBCL) is the most common subtype of aggressive non-Hodgkin lymphoma (NHL) and is curable with first-line conventional chemotherapy, but a significant fraction of patients relapse or do not respond to initial therapy. There are a variety of treatments available for relapsed/refractory (RR) disease, including platinum-based salvage chemotherapy often used historically both with or without autologous stem cell transplant, and chimeric antigen receptor T-cell (CAR-T) therapy emerging more recently as a second-line option. We report survival data following 2 ^nd and 3 ^rd line therapy for RR DLBCL in a large contemporary prospective cohort.

Methods: We selected patients (pts) from the Lymphoma Innovations ORIEN Network (LION) with diffuse large B-cell lymphoma, not otherwise specified and high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (“double-hit” lymphoma) who had previously received R-CHOP chemotherapy. All patients had signed written consent. Clinical data were abstracted from medical records using standardized protocol. Overall survival was estimated using Kaplan-Meier and defined as time from start of 2 ^nd (OS2) or 3 ^rd (OS3) line treatment until death, censoring patients alive at last follow-up. Comparisons of OS were performed using the log-rank test.

Results: A total of 328 patients with RR DLBCL who received 2 ^nd line treatment were included, 177 of whom went on to receive 3 ^rd line therapy. Baseline characteristics included male sex in 205 pts (65%), stage III/IV disease in 244 pts (81%), and extranodal involvement in 183 pts (63%). Second line treatments included platinum-based salvage chemotherapy both with (99 pts) and without (88 pts) autologous stem cell transplant, rituximab plus gemcitabine and oxaliplatin (30 pts, grouped distinctly from platinum-based salvage chemotherapy), CAR-T therapy (43 pts), polatuzumab vedotin (17 pts), and other classes of treatment (51 pts). Median OS2 for 2 ^nd line platinum-based salvage chemotherapy with autologous transplant was 110.4 months compared with 50.4 months for platinum-based salvage chemotherapy without transplant. OS2 for platinum-based salvage chemotherapy with autologous transplant was 96.5% (95% CI 90-99) at 12 months, 90.7% (95% CI 81-96) at 24 months, and 79.3% (95% CI 67-88) at 60 months compared with 77.1% (95% CI 66-85) at 12 months, 65.5% (95% CI 52-76) at 24 months, and 38.1% (95% CI 21-55) for platinum-based salvage without transplant. OS2 for rituximab plus gemcitabine and oxaliplatin was 81.7% (95% CI 58-93) at 12 months, still 81.7% (95% CI 58-93) at 24 months, and 70.1% (95% CI 37-88) at 60 months. OS2 for CAR-T cell therapy was 75% (95% CI 50-89) at 12 months and 62.5% (95% CI 36-80) at 24 months, it could not be calculated at 60 months. OS2 for polatuzumab vedotin was 73.5% (95% CI 36-91) at 12 months and could not be calculated at 24 or 60 months. OS3 for platinum-based salvage chemotherapy with autologous transplant was 100% at 12 months and 83.3% (95% CI 27-98) at 24 months compared with 70.7% (95% CI 34-90) at both 12 and 24 months for platinum-based salvage without transplant. OS3 for rituximab plus gemcitabine and oxaliplatin was 75% (95% CI 13-96) at 12 months and 50% (95% CI 6-85). OS3 for CAR-T therapy was 86.3% (95% CI 75-93) at 12 months, 65.8% (95% CI 50-78) and 46.3% (95% CI 22-68) at 60 months. OS3 for polatuzumab vedotin was 53.4% (95% CI 24-76) at 12 months and 40.1% (95% CI 12-67) at 24 months.

Conclusions: We observed a statistically significant difference by log-rank in OS2 in patients receiving platinum-based salvage chemotherapy followed by autologous stem cell transplant compared to other therapies in a contemporary cohort of pts with RR DLBCL. This difference is likely driven in part by transplant being a surrogate marker for efficacy of salvage chemotherapy. OS3 was also highest at 12, 24, and 60 months in patients receiving platinum-based salvage chemotherapy followed by transplant. Other therapies including CAR-T cells, polatuzumab vedotin, and rituximab plus gemcitabine and oxaliplatin did not demonstrate significantly different rates of overall survival in the 2 ^nd or 3 ^rd line setting.