Pre-clinical evaluation of NEOS-223, an (S)-valine-thiazole derived peptidomimetic N-heterocycle, as an anticancer agent and P-glycoprotein inhibitor

ABSTRACT

The ability to control the proliferation and cell death by inhibiting specific target kinase offers the opportunity to apply targeted therapies in the treatment of cancer. It has been found that (S)-valine-thiazole-derived compounds such as NEOS-223 are effective inhibitors of one or more of these kinases. NEOS 223 was developed, synthesized, and tested in the NCI 60 human tumor cell-screening panel demonstrating inhibition of colon (-53%), melanoma (-41%), and breast cancers (-9%). Microsomal clearance was determined in mouse, rat, dog, and human, and analyzed by LC-MS/MS by percent of parent material. IC50 values for CYP inhibition of >10 μM were calculated for 1A2, 2C19, and 3A4 with IC50 values of 4.86, 4.31, and 7.84 μM for 2C9 and 2D6. Microsomal clearance was high in all species with clearance rates ranging from 69-136 mL/min/kg. Plasma protein binding was determined by Rapid Equilibrium Dialysis in mice, rats, dogs, and humans. High plasma protein binding (>70%) was observed across all species. Based on the NCI results several cell lines were assayed in an MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) to determine cell viability in the presence of NEOS-223 resulting in <20% viability in colon, breast, melanoma, pancreatic and prostate human cancer cell lines at a 10 uM concentration. Maximum tolerated dose studies were conducted by both intraperitoneal and oral administration in mice. NEOS-223 delivered up to 80 mg/kg was well tolerated. Minimal or no toxicity was observed in acute and repeat dose animal studies. Pharmacokinetics of oral administration demonstrated adequate systemic exposure at therapeutic levels in mice, rats, and dogs. Preliminary in vivo mouse xenograft studies were performed on colon (COLO 205, HT-29 red FLUC), breast (MDA-Sumathi Chittamuru;Timothy M. Murphy;Sara A. Little;Andrew A. Taylor;Roseanne Wexler;Laxman Desai MB-468), melanoma (M-14), pancreatic (PANC-1), and prostate (PC3) human cancer cells with significant tumor inhibition observed compared to positive control agent groups with twice daily dosing of NEOS-223. In addition, a five-day pilot oral toxicity study in rats with dose range-finding studies and a 28-day repeat dose toxicity study performed in both rats and dogs provided favorable results. NEOS-223 has demonstrated active in vitro activity along with a favorable safety profile. in vivo efficacy resulted in inhibition of growth of multiple cell line. As a novel effective structure possibly targeting multiple kinases and transporters in one hybrid molecule, NEOS-223 may be a preferred monotherapy or combined therapy for multiple cancers. If upon further development, this drug is effective in humans, it would advance clinical practice and could improve current therapy significantly.