alkylation, and EMD, anti-angiogenic, cytotoxicity, efficacy studies, melflufen, melphalan flufenamide, Multiple Myeloma, Oncology, Orphan Drug, peptidase targeting, peptide conjugated alkylator, peptide-drug conjugate, phase 1, Phase 2, Phase 3, Plasma Cell Myeloma, Relapsed & Relapsed-Refractory Multiple Myeloma, RRMM