title: In vitro and in vivo antitumor activity of a novel alkylating agent, melphalan-flufenamide, against multiple myeloma cells.
abstract: OBJECTIVE
  The alkylating agent melphalan prolongs survival in patients with multiple myeloma; however, it is associated with toxicities and development of drug-resistance. Here, we evaluated the efficacy of melphalan-flufenamide (mel-flufen), a novel dipeptide prodrug of melphalan in multiple myeloma.
  
  
  METHODS
  Multiple myeloma cell lines, primary patient cells, and the human multiple myeloma xenograft animal model were used to study the antitumor activity of mel-flufen.
  
  
  RESULTS
  Low doses of mel-flufen trigger more rapid and higher intracellular concentrations of melphalan in multiple myeloma cells than are achievable by free melphalan. Cytotoxicity analysis showed significantly lower IC50 of mel-flufen than melphalan in multiple myeloma cells. Importantly, mel-flufen induces apoptosis even in melphalan- and bortezomib-resistant multiple myeloma cells. Mechanistic studies show that siRNA knockdown of aminopeptidase N, a key enzyme mediating intracellular conversion of mel-flufen to melphalan, attenuates anti-multiple myeloma activity of mel-flufen. Furthermore, mel-flufen-induced apoptosis was associated with: (i) activation of caspases and PARP cleavage; (ii) reactive oxygen species generation; (iii) mitochondrial dysfunction and release of cytochrome c; and (iv) induction of DNA damage. Moreover, mel-flufen inhibits multiple myeloma cell migration and tumor-associated angiogenesis. Human multiple myeloma xenograft studies showed a more potent inhibition of tumor growth in mice treated with mel-flufen than mice receiving equimolar doses of melphalan. Finally, combining mel-flufen with lenalidomide, bortezomib, or dexamethasone triggers synergistic anti-multiple myeloma activity.
  
  
  CONCLUSIONS
  Our preclinical study supports clinical evaluation of mel-flufen to enhance therapeutic potential of melphalan, overcome drug-resistance, and improve multiple myeloma patient outcome.
authors.affiliation: The LeBow Institute for Myeloma Therapeutics and Jerome Lipper Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02215, USA. Dharminder_Chauhan@dfci.harvard.edu
authors.forename: Dharminder
authors.initials: D
authors.lastname: Chauhan
authors.forename: Arghya
authors.initials: A
authors.lastname: Ray
authors.forename: Kristina
authors.initials: K
authors.lastname: Viktorsson
authors.forename: Jack
authors.initials: J
authors.lastname: Spira
authors.forename: Claudia
authors.initials: C
authors.lastname: Paba-Prada
authors.forename: Nikhil
authors.initials: N
authors.lastname: Munshi
authors.forename: Paul
authors.initials: P
authors.lastname: Richardson
authors.forename: Rolf
authors.initials: R
authors.lastname: Lewensohn
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Anderson
mesh_terms: D020533:Angiogenesis Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004195:Disease Models, Animal; D004357:Drug Synergism; D005260:Female; D006801:Humans; D008558:Melphalan / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D051379:Mice; D009101:Multiple Myeloma / Q000188:drug therapy / Q000401:mortality / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D010649:Phenylalanine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D018906:Antineoplastic Agents, Alkylating; C585069:melflufen; D010649:Phenylalanine; D008558:Melphalan