P1183: central nervous system involvement at diagnosis and at relapse in patients with peripheral t-cell lymphoma: a retrospective analysis of the “rete ematologica veneta” (t-rev project).

Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical Background: Peripheral T-cell lymphoma (PTCL), is a heterogeneous and rare entity (5-10% of all lymphomas). Central nervous system (CNS) involvement at diagnosis and at relapse in patients with PTCL ranged from 2-9%, with a well-known dismal prognosis. There are no clear recommendations for CNS prophylaxis in PTCL, with the exception of some entity. We retrospectively collected clinicopathologic and treatment data from 205 PTCL patients, diagnosed between 2000 and 2022, who underwent induction chemotherapy in six Italian centers. Aims: To characterize the rate and survival outcome of CNS involvement in newly diagnosed PTCL. Methods: Routine staging investigations and response was evaluated using the 2014 Lugano criteria. The diagnosis of PTCL was histologically confirmed and categorized according to the classification at the time of diagnosis. Patients with primary cutaneous T-cell lymphoma, T-cell lymphoblastic leukemia/lymphoma, T-cell prolymphocytic leukemia, adult T-cell leukemia/lymphoma and extranodal NK/T-cell lymphoma were excluded from this study. Only 6 patients received CNS prophylaxis, 3 with intrathecal therapy and 3 with high-dose methotrexate. Results: Baseline characteristics are shown in Figure 1. The median age of the entire population was 72 years (range 28-90), with a predominance of PTCL, not otherwise specified. With a median follow up of 24 months, 10 patients out of 205 had CNS disease: four patients (1.5%) had CNS involvement at initial diagnosis (1 ALCL-ALK+ and 3 ALCL-ALK-) and 6 patients (2.5%) experienced a CNS relapse (3 PTCL-NOS, 2 AITL, 1 EATL). At the end of first line treatment, ORR was 65% (with 55% CR and 10% PR) in patients without CNS involvement at diagnosis, and only one CR (25%) in patients with CNS involvement at diagnosis. Median overall survival (OS) of the entire population was 38 months; primary refractory and early relapsed were 69 (35%) and 33 (17%) patients, with a median OS of 8 and 21 months, respectively. Median OS for patients with CNS relapse were 8 months, and median OS for cases with CNS involvement at diagnosis were 13 months. As previously reported, patients relapsing to CNS were all in stage IV, had an elevated LDH, with extranodal involvement ≥ 1 site. CNS relapse had inferior survival, and it usually manifests as a terminal events in patients with refractory disease Summary/Conclusion: In this small multicenter retrospective analysys, we confirmed that patients with PTCL, developing a CNS relapse, had a higher burden of disease at baseline with a very poor prognosis. PTCL is a group of disease generally considered at low risk of CNS involvement at diagnosis and relapse; prophylaxis should be stratified according to histologic subtypes and risk factors. Further studies are needed to prevent and treat this condition, aiming to define a more individualized therapeutic approaches.Keywords: Peripheral T-cell lymphoma