P1161: therapy and outcome in relapsed and refractory peripheral t-cell lymphoma: a contemporary and nationwide population-based study in the netherlands.

Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical Background: 1st line treatment for peripheral T-cell lymphoma (PTCL) consists of polychemotherapy like cyclophosphamide, doxorubicin, vincristine and prednisone, with or without etoposide (CHO(E)P) followed by consolidation with intensive chemotherapy (BEAM) and autologous stem cell transplantation (ASCT). A significant proportion of patients are refractory to 1st line treatment or relapse (R/R). The treatment landscape of R/R PTCL varies, and the optimal treatment remains largely unknown as clinical studies are scarce. Aims: This nationwide, population-based study mapped treatment strategies and outcome among patients with R/R PTCL not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL) and anaplastic large T-cell lymphoma (ALCL). Methods: All patients with PTCL ≥18 years diagnosed between 2014-2019 were identified in the Netherlands Cancer Registry, with survival follow-up through February 1st, 2022. Response to treatment was determined by physician assessment. Overall survival (OS) was defined as the time between diagnosis and death and progression-free survival (PFS) as the time between diagnosis and first relapse or death. For R/R patients, OS2 and PFS2 were evaluated from date of relapse. Multivariable analysis of OS was performed using Cox regression. Results: A total of 821 patients were identified, including 32% PTCL-NOS, 37% AITL and 30% ALCL patients. In 1st line, 22% received CHO(E)P followed by BEAM/ASCT, 66% CHO(E)P only and 12% other. The complete remission (CR) rates according to CHO(E)P w/ or w/o ASCT or other therapy were 88%, 45% and 31% respectively (p<0.01). Progressive disease and relapse after complete remission was observed for 7% and 30% of patients respectively. Two-year PFS and OS estimates were 45% and 57%, respectively. Of the 311 R/R PTCL patients, 78% received 2nd line treatment: 44% DHAP/GDP, 20% brentuximab vedotin (BV) and 36% other. The overall response rate (ORR) was 47% of whom 35% (n=84) achieved a CR. CR rates were 40%, 43% and 23% (p=0.02) for DHAP/GDP, BV and other therapy, respectively. The 2-year PFS2 and OS2 estimates for patients treated in 2nd line were 21% and 29%, respectively. Risk of mortality was adversely effected by age per year increment (HR 1.02; 95% CI 1.01-1.03), relapse within 12 months of diagnosis (HR 1.75; 95%CI 1.27-2.40), and PTCL-NOS subtype (HR 1.74; 95%CI 1.16-2.61). Among 84 patients treated in 3rd line, the ORR was 43% of whom 25% achieved a CR. Because of cross-over between treatments in 2nd and 3rd line, survival data for DHAP/GDP and BV were analyzed separately. The 2-year PFS2 and OS2 for patients treated with DHAP/GDP were 20% and 36%. A landmark analysis at 6 months among 33 out of 107 DHAP/GDP patients consolidated with SCT showed a 2-year PFS2 and OS2 of 53% and 68%, respectively. For 77 patients treated with BV, the 2-year PFS2 and OS2 was 31% and 44%, respectively. Of these patients, 30 reached a CR with a 2-year OS of 73%. The 2-year OS2 was similar for patients who did or did not received consolidative SCT after BV(p=0.70). Summary/Conclusion: In this population-based study, most commonly applied treatment strategies were DHAP/GDP and BV for R/R PTCL patients. Among patients treated with DHAP/GDP the CR rate was 40%. Consolidation with SCT after DHAP/GDP improved PFS and OS, although this only applies for the minority of these patients. Among patients treated with BV, 43% achieved a CR with a favorable 2-year OS2.Fig 1. Treatment strategies among 821 patients with peripheral T-cell lymphoma (PTCL- NOS, AITL and ALCL) in 1st, 2nd and 3rd line treatment. Keywords: T cell lymphoma, NHL