This is a phase 1/2, open label, single-center study designed to assess the safety and preliminary clinical activity of different belantamab mafodotin doses in combination with daratumumab, pomalidomide, and dexamethasone (DPd) in patients with Relapsed/ Refractory Multiple Myeloma (RRMM) previously treated with one line of therapy who are lenalidomide refractory.

This will be a 2-Part study. Part 1 will evaluate the safety of belantamab mafodotin in combination with DPd in 2 cohorts and determine the Recommended Phase 2 Dose (RP2D). In the dose expansion phase (Part 2) an expansion cohort will be treated with the RP2D. The expansion cohort will randomize participants (1:1) in two groups to evaluate two alternate dose modification guidelines for corneal AEs. Part 2 will further evaluate the safety and assess the preliminary clinical activity of the belantamab mafodotin RP2D in combination with DPd.

Overall, approximately 48 participants will be enrolled in the study. Participant follow-up will continue up to 3 years after the last participant is randomized. The estimated accrual period will be 12 months corresponding to an approximate total study duration of 4 years.