NCMP-18. NEUROTOXICITY AS A POTENTIAL SURROGATE MARKER FOR THERAPEUTIC RESPONSE WITH COMMERCIAL ANTI-CD19 CAR T-CELL THERAPY

Neurotoxicity is a common occurrence and a major form of morbidity in adult patients with relapsed or refractory (R/R) diffuse large B cell lymphoma (DLBCL) patients treated with anti-CD19 directed chimeric antigen receptor (CAR) T-cell therapy. Variables related to the incidence and severity of neurotoxicity have been relatively well delineated, but the association between neurotoxicity and the efficacy of CAR T-cell therapy has not been well studied. We performed a retrospective analysis of the outcomes of DLBCL patients who developed neurotoxicity following anti-CD19 CAR T-cell treatment. The analysis included 26 patients with R/R DLBCL who received commercial anti-CD19 CAR T-cell therapy. All patients received a lymphodepleting chemotherapy regimen consisting of fludarabine and cyclophosphamide. Twenty-five patients received axicabtagene ciloleucel, and 1 received tisagenlecleucel. The overall incidence of neurotoxicity was 88%; 31% developed severe neurotoxicity (Grade III-IV by CTCAE). Higher neurotoxicity was associated with better PFS by both CTCAE (CR 2.4 ± 1.1 vs. PD 1.4 ± 1.3, p = 0.051) and CARTOX-10 (CR 3.78 ± 4.6 vs. PD 7.7 ± 3.8, p = 0.044) grading systems. Higher neurotoxicity continued to show a trend at 6, 9, and 12 months by the CTCAE grading system (CR 2.4 ± 1.0 vs. PD 1.7 ± 1.3, p = 0.085), and no patients had disease recurrence after 6 months. In this limited cohort, neurotoxicity severity was paradoxically positively correlated with progression-free survival with commercial CAR T-cell therapy and may therefore indicate an effective therapeutic response.