Pre-transplant Purging and Post-transplant MRD-guided Maintenance Therapy With Elranatamab in Patients With High-risk Multiple Myeloma

Primary Objectives * To determine the overall proportion of high-risk MM participants achieving sustained MRD-negative CR status after the completion of the treatment plan including in-vivo purging with elranatamab, auto-HCT, and post-transplant maintenance therapy. Sustained MRD-negativity is defined as MRD-negative status in two assessments, at least 1-year apart, without any MRD-positive status in between. * To determine the proportion of patients with clonal plasma cell negative autograft collection in participants with high-risk MM. Secondary Objectives * To assess the impact of elranatamab on hematopoietic progenitor cell mobilization and collection yield. * To determine the safety and tolerability of elranatamab plus lenalidomide maintenance therapy after auto-HCT. * To detect the MRD-negative rate before auto-HCT with in-vivo purging using elranatamab. * To detect the MRD-negative rate after auto-HCT. * To determine overall response rates as defined by the International Myeloma Working Group (IMWG). * To determine the PFS and OS with elranatamab plus lenalidomide maintenance therapy after auto-HCT in participants with high-risk NDMM. * To determine the PFS and OS in participants with high-risk NDMM who discontinue maintenance therapy after achieving CR plus sustained MRD-negative status. * To determine the PFS and OS with elranatamab plus lena