PC-046 is a potent tubulin-binding agent, which was originally identified for development based on selective activity in deleted in pancreas cancer locus 4 (DPC4 SMAD4) deficient tumors. PC-046 has growth inhibitory activity in a variety of tumor types in vitro, and efficacy in SCID mice was shown in human tumor xenografts of MV-4-11 acute myeloid leukemia, MM.1S multiple myeloma, and DU-145 prostate cancer. Pharmacokinetic studies demonstrated relatively high oral bioavailability (71 %) with distribution to both plasma and bone marrow. No myelosuppression was seen in non-tumor bearing SCID mice given a single dose just under the acute lethal dose. The COMPARE algorithm in the NCI-60cell line panel demonstrated that PC-046 closely correlated to other known tubulin destabilizing agents (correlation coefficients ≈0.7 for vincristine and vinblastine). Mechanism of action studies showed cell cycle arrest in metaphase and inhibition of tubulin polymerization. Overall, these studi......
RKS262 is a specific cyclin CDK inhibitor. RKS262 was identified by structural optimization of Nifurtimox which is currently undergoing phase II clinical trials to treat high-risk neuroblastoma. In a NCI(60) cell-line assay RKS262 exhibited significant cytotoxicity in ovarian cancer cells and a variety of other cell lines exceeding effects of commercial drugs such as cisplatin, 5-FU, cyclophosphamide or sapacitabine. Various leukemia cell-lines were most sensitive (GI(50): ~ 10 nM) while several non-small cell lung cancer cell lines and few cell lines from other tissues were relatively resistant (GI(50) > 1 µM) to RKS262 treatment.