Phase 2 Study Evaluating Rapcabtagene Autoleucel in Participants With Diffuse Cutaneous Systemic Sclerosis

This is a phase 2, multi-part, five-year, randomized, open-label, assessor-blinded, multicenter study to evaluate the efficacy and safety of rapcabtagene autoleucel versus rituximab in participants with severe refractory diffuse cutaneous systemic sclerosis (dcSSc). This study comprises two cohorts: * A Lead-in Cohort enrolling participants to receive rapcabtagene autoleucel. * A Randomized Cohort enrolling participants to receive rapcabtagene autoleucel or rituximab. Participants in the rituximab arm whose disease is not fully controlled may receive rapcabtagene autoleucel treatment once the participant is confirmed to be eligible per protocol. After end of study, participants who received rapcabtagene autoleucel infusion will enter a long-term follow-up (LTFU) period after rapcabtagene autoleucel infusion. This LTFU will be described in a separate study protocol.