Minimal Residual Disease Guided Maintenance Therapy With Belantamab Mafodotin and Lenalidomide After Autologous Hematopoietic Cell Transplantation in Patients With Newly Diagnosed Multiple Myeloma

To increase the conversion rate from MRD-positive to MRD-negative CR in patients with newly diagnosed multiple myeloma (NDMM) receiving post-transplant maintenance therapy with belantamab mafodotin plus lenalidomide.

Inclusion Criteria: * Patients with newly diagnosed multiple myeloma status post 1st auto-HCT (day 60 - 180 post-transplant). * Disease status (MRD positive or negative), partial response, or better. * Age \> 18-year and 75-year. Non-English speaking patients are eligible. * Karnofsky performance status 70 (Appendix A.). * Adequate organ function (Please see Table 2. below). Participant agrees to not donate blood while taking lenalidomide and for 28 days after stopping lenalidomide. * Patient agrees to enroll in the lenalidomide REMS program. * Woman of child-bearing potential (WOCPB) must abstain from hetersosexual sexual contact or agrees to use a contraceptive method that is highly effective (with a failure rate of \1 year. * Patients who have been amenorrhoeic for \