Heterogeneous expression of drug target proteins within tumor sites is a major mechanism of resistance to anticancer therapies. We describe a strategy to selectively inhibit, within tumor sites, the function of a critical intracellular protein, the sarcoplasmic/endoplasmic reticulum calcium adenosine triphosphatase (SERCA) pump, whose proper function is required by all cell types for viability. To achieve targeted inhibition, we took advantage of the unique expression of the carboxypeptidase prostate-specific membrane antigen (PSMA) by tumor endothelial cells within the microenvironment of solid tumors. We generated a prodrug, G202, consisting of a PSMA-specific peptide coupled to an analog of the potent SERCA pump inhibitor thapsigargin. G202 produced substantial tumor regression against a panel of human cancer xenografts in vivo at doses that were minimally toxic to the host. On the basis of these data, a phase 1 dose-escalation clinical trial has been initiated with G202 in patients with advanced cancer.
Written by:
Denmeade SR, Mhaka AM, Rosen DM, Brennen WN, Dalrymple S, Dach I, Olesen C, Gurel B, Demarzo AM, Wilding G, Carducci MA, Dionne CA, Møller JV, Nissen P, Christensen SB, Isaacs JT Are you the author?
The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
Reference: Sci Transl Med. 2012 Jun 27;4(140):140ra86
doi: 10.1126/scitranslmed.3003886
PubMed Abstract
PMID: 22745436
