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Novel Peptide-drug Conjugate Melflufen Efficiently Eradicates Bortezomib-resistant Multiple Myeloma Cells Including Tumor-initiating Myeloma Progenitor Cells

Konstantin Byrgazov, Andrej Besse, Marianne Kraus, Ana Slipicevic, Fredrik Lehmann, Christoph Driessen & Lenka Besse

abstract Introduction of the proteasome inhibitor bortezomib has dramatically improved clinical outcomes in multiple myeloma. However, most patients become refractory to bortezomib-based therapies. On the molecular level, development of resistance to bortezomib in myeloma cells is accompanied by complex metabolic changes resulting in increased protein folding capacity, and less dependency on the proteasome. In this study, we show that aminopeptidase B, encoded by the gene, is upregulated in bortezomib-resistant myeloma cell lines, and in a murine in vivo model. Moreover, increased expression is associated with shorter survival in multiple myeloma patients previously treated with bortezomib-containing regimens. Additionally, expression is increased in plasma cell precursors, a B-lymphoid compartment previously associated with myeloma stem cells. We hypothesized that increased aminopeptidase B expression in aggressive myeloma clones may be used therapeutically toward elimination of the cells via the use of a novel peptide-drug conjugate, melphalan flufenamide (melflufen). Melflufen, a substrate of aminopeptidase B, efficiently eliminates bortezomib-resistant myeloma cells in vitro and in vivo, and completely suppresses clonogenic myeloma growth in vitro at subphysiological concentrations. Thus, melflufen represents a novel treatment option that is able to eradicate drug-resistant myeloma clones characterized by elevated aminopeptidase B expression.
   
citation Byrgazov K, Besse A, Kraus M, Slipicevic A, Lehmann F, Driessen C, Besse L. Novel Peptide-drug Conjugate Melflufen Efficiently Eradicates Bortezomib-resistant Multiple Myeloma Cells Including Tumor-initiating Myeloma Progenitor Cells. Hemasphere 2021; 5:e602.
   
type journal paper/review (English)
date of publishing 12-06-2021
journal title Hemasphere (5/7)
ISSN electronic 2572-9241
pages e602
PubMed 34136753
DOI 10.1097/HS9.0000000000000602