Clinical impact of [18F]FDG-PET/CT in ARI0002h treatment, a CAR-T against BCMA for relapsed/refractory multiple myeloma

• <div id="vidyowebrtcscreenshare_is_installed">PFS and OS are shorter in patients with extramedullary plasmacytomas evaluated by [18F]FDG-PET/CT at infusion time.</div>

• <div id="vidyowebrtcscreenshare_is_installed">Survival is predicted by a metabolic tumor volume of 25cm3 or more at baseline and [18F]FDG-PET/CT response (Bologna Criteria) on day 100.</div>

Multiple myeloma (MM) remains incurable, with poor outcomes in heavily pre-treated patients with plasmacytomas. Chimeric antigen receptor (CAR) T-cell therapy has emerged as a promising treatment option; however, outcomes after such therapy in patients with soft-tissue plasmacytomas and other bone lesions remain poorly understood. Data regarding these parameters is scarce within the specific context of CAR T-cell treatment. This study included 63 patients with relapsed/refractory MM (RRMM), treated either in the CARTBCMA-HCB-01 clinical trial (ARI0002h; academic BCMA-targeted CAR T-cell therapy) or due to compassionate use. The aim was to evaluate the impact of soft-tissue involvement (extramedullary [EMD] and paraskeletal [PS] plasmacytomas) in response, survival and safety. Baseline [18F]FDG-PET/CT from five participating centers were reviewed centrally. Of the 63 patients, 52.4% presented plasmacytomas at the time of inclusion (21 PS, exclusively, and 12 EMD). Per responses, there were no significant differences between patients with and without plasmacytomas. A correlation was present between IMWG responses and those obtained by [18F]FDG-PET/CT at day 100 (Bologna Criteria). No differences were observed in progression-free survival (PFS) or overall survival (OS) between patients with or without plasmacytomas. However, both PFS and OS were significantly shorter in patients with EMD. Interestingly, [18F]FDG-PET/CT response assessed on day 100, in accordance with the Bologna Criteria, was predictive of survival outcomes. A metabolic tumor volume (MTV) of 25 or more at baseline [18F]FDG-PET/CT was associated with earlier disease progression and a shorter OS. These results highlight the importance of EMD evaluation by [18F]FDG-PET/CT before and after CAR T-cell infusion. NCT04309981, and EudraCT, 2019-001472-11