Abstract

7519 Background: CART therapy represents a breakthrough in therapy for patients (ptns) with relapsed or refractory (R/R) multiple myeloma (MM). Pts with MM who have CNS involvement are commonly excluded from clinical trials and have limited therapeutic options. We evaluated the safety and efficacy of BCMA-directed CART therapies in ptns with MM and CNS involvement. Methods: 5 US academic medical centers contributed data to this retrospective analysis. 11 ptns with MM with CNS involvement received BCMA-directed CART (7 and 4 pts received ide-cel and cilta-cel, respectively). Results: Eight (72%) ptns were male, 3 (27%) had high-risk (HR) cytogenetics, and 10 (91%) had extramedullary disease (dz). Four (36%) ptns had brain/cranial nerve dz, 1 (9%) had spine dz, and 6 (55%) had both. CNS dz was evident on MRI in 100% of ptns and on CSF in 4 ptns (36%). Five ptns (45%) had ≤60 days between CNS diagnosis and CART therapy, 3 (27%) had >300 days from CNS dz with 2 requiring CNS-directed therapy (CNS-Tx) close to CART during bridging, and 3 (27%) were diagnosed soon after CART infusion. Six (55%) ptns received CNS-Tx as part of bridging; radiotherapy (RT, 2 ptns), RT + intrathecal (IT) chemotherapy (chemo) (2 ptns), IT chemo (1 ptn), and surgery + RT (1 ptn). Five (45%) ptns didn’t receive CNS-Tx as part of bridging for the following reasons; 3 were diagnosed soon post CART and received RT post-infusion, 1 had recent chemo, and 1 was treated for CNS dz 587 days prior to CART and didn’t require CNS-Tx during bridging. Seven ptns (64%) had treated CNS dz at the time of lymphodepleting chemo. Nine (82%) ptns had grade (G) 1/2 CRS and none had G ≥3CRS. Two ptns (18%) had G1 ICANS, 1 (9%) had G3 ICANS, and none had G4 ICANS. Two ptns experienced delayed neurotoxicity post ide-cel, 1 with delayed lethargy that was treated with steroids, and the other with progressive multifocal leukoencephalopathy that was treated with steroids plus pembrolizumab. None had delayed parkinsonian side effects. With a median follow-up of 104 days post-infusion, the best responses achieved were 45% CR/sCR, 18% VGPR, 9% PR, with an overall response (ORR) of 73%. Seven ptns were evaluable for CNS responses by day 90 with a 100% CNS response rate defined by improved imaging findings or clearance of CSF involvement. CNS recurrence occurred in 1 ptn (9%) by day 172 while 5 (45%) had continued systemic response at last assessment. Conclusions: This study suggests that BCMA directed CART therapy in ptns with MM and CNS involvement is safe and feasible. Of the evaluable ptns for CNS response, 100% showed CNS response by day 90. Larger studies with longer follow up are needed to confirm these findings. [Table: see text]