Abstract

2006 Background: Prognosis of patients with relapsed/refractory (R/R) CNSL is poor with no standard of care treatment options. Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy axicabtagene ciloleucel (axi-cel) has shown efficacy in R/R systemic large B-cell lymphoma (LBCL) and could be considered for R/R CNSL. Methods: We conducted a pilot study of axi-cel in patients with R/R CNS LBCL. No bridging therapy except corticosteroids was allowed after enrollment. Ommaya reservoir was placed before infusion. Patients underwent lymphodepletion with fludarabine and cyclophosphamide followed by axi-cel dosing of 2x10 6 cells/kg intravenous infusion. The study enrolled 18 patients, of whom the first 6 patients were observed for treatment-limiting toxicities (TLTs). Primary endpoint was safety, measured by rate of TLTs and grade 3+ adverse events (AEs). Secondary endpoints included objective response rate (ORR), complete response (CR) rate, duration of response (DOR), progression-free survival (PFS) and overall survival (OS). Exploratory analyses include paired peripheral blood (PB) and CSF analyses for axi-cel pharmacokinetics, pharmacodynamics, flow cytometry, single-cell RNA-Seq. Results: We report the results of the entire cohort of 18 patients (13 PCNSL, 4 SCNSL, 1 concurrent systemic & ocular L) enrolled. Median age was 62 years (33-80), 8/18 were women. Median number of prior therapies was 3 (1-7). No TLTs were observed; 16/18 (89%) patients developed cytokine release syndrome/CRS (grade 3+, 0%); 8/18 (44%) developed immune effector cell-associated neurologic syndrome/ICANS, 5/18 (28%) grade 3+. Two patients developed Ommaya-related meningitis requiring explant with recovery. One patient had grade 3 seizures that resolved with anti-epileptic agents. The ORR was 94% (17/18); 67% CR (12/18). The median time to best response was 3 months. As of January 25, 2024, the median follow up was 24.2 months, median DOR 13.4 months and 9 patients had progressed. The median PFS was 14.3 months (95% CI: 6.3-NR) and median OS, 26.4 months (95% CI: 11.2-NR). Seven patients have died, all from disease progression. At the time of presentation, there will be a minimum follow-up of 12 months. Correlative data on all 18 patients will be presented at the meeting. Axi-cel pharmacokinetics in the first 12 CNSL patients was similar to that previously reported for DLBCL patients without CNS involvement in ZUMA-1 and ZUMA-7. Patients with CR demonstrated increased peak levels of pro-inflammatory cytokines. CSF CAR T cells exhibit Type I interferon (IFN) transcriptomic signature compared to proliferative signature in blood. Conclusions: Axi-cel was safe and well-tolerated in CNSL patients with encouraging efficacy and median PFS and durability of response of more than 1 year. There was no apparent additional risk of adverse neurologic events including ICANS from axi-cel. Clinical trial information: NCT04608487 .