Hm-032, A Novel Pi3k/Mtor Dual Inhibitor, Is Active On K-Ras/Raf Mutation Tumors Through Up-Regulation Of Bim

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL PIK3CA gene amplification and mutations have been identified in many types of tumors, suggesting the deregulation of PI3K/AKT/mTOR axis plays pivotal roles in tumorigenesis and development. K-Ras/Raf mutation is recognized as one of the key drug resistant factors for tumors against TKIs. HM-032 was reported here as a potent, selective and reversible ATP-competitive PI3K/mTOR dual inhibitor with special apoptotic activity in tumor cells harboring K-Ras mutations. HM-032 showed potent kinase inhibition with IC50 of 0.0008, 0.002, 0.001, 0.002 and 0.001 µM on PI3Kα, β, δ, ≤ and mTOR, respectively. In human prostate PC3 cells, it inhibited p-AKTS473, p-S6 and p-4EPB1 with IC50s of 0.002, 0.015 and 0.056 μM. Of the 89 tumor cell lines from lung, colon, breast, ovarian, and other tumor types, it was found that tumor cells with HER2 gene amplification, or PIK3CA mutation were relatively more sensitive to HM-032. Attractively, HM-032 showed apoptotic induction activity in the tumor cells harboring Ras/Raf mutations through inhibiting p-Erk and increasing gene expression of pro-apoptotic protein Bim. This result suggested that HM-032 might bring benefits to patients carrying K-Ras/Raf mutations in the clinic. Consistent with in vitro studies, HM-032 exhibited significant tumor growth inhibition in a dose dependent manner on multiple human xenograft models, including breast tumor MDA-MB-361(PIK3CAE545K, Her2 amplification), lung tumors H460 (PIK3CAE545K, K-RasQ61H) and A549 (LKB1 del, K-RasG12S), and glioblastoma U87MG (PTEN del) after 3 weeks oral dosing. Correspondingly, decrease of p-AKT and p-S6 was observed in the tumor xenograft tissues upon treatment with HM-032. In addition, HM-032 exhibited unique in vivo PK properties characterized by low clearance and long t1/2, which supported the intermittent dosing schedule in xenograft models. Based on the pre-clinical study results, HM-032 is anticipated to be a promising agent against solid tumors including carrying Ras/Raf mutations. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1808. doi:1538-7445.AM2012-1808