Description: IMPACT has discovered two series of novel PARP inhibitors with more than 60 novel compounds that are many folds more potent than AZD2281 (olaparib) in multiple in vitro assays. We have selected IMP4297 as a clinical candidate for development based on excellent pharmacological and safety profiles. IMP4297 is not only much more potent but also more selective than AZD2281 against cells with BRCA mutation vs normal cells. In efficacy studies IMP4297 was 20-fold more potent than AZD2281 in a BRCA1 deficient MDA-MB-436 human breast cancer xenograft mouse model, as well as in a PDX (patient-derived xenograft) mouse model with BRCA1 mutated human triple negative breast cancer. Importantly, IMP4297 caused tumor regression with little body weight change (<5%), and was much more efficacious than AZD2281, consistent with the high in vitro selectivity of IMP4297. In comparison with AZD2281, IMP4297 is not only much more potent, but much more efficacious, with a large therapeutic window in vivo. IMP4297 has the potential to be developed as a “best-in-class” PARP inhibitor for the treatment of cancers with BRCA mutations, including breast, ovarian and prostate cancers. An IND application for IMP4297 has been submitted in China and accepted for review by CFDA.
IP: Five patent applications have been filed for these novel PARP inhibitors, and three patents in China and three patents in the US have been granted.
Future Plan: We plan to initiate IMP4297 phase Ia clinical studies to determine MTD in Australia in 2016, followed by phase Ib studies in Australia/China to obtain preliminary efficacy data in patients with BRCA mutations. Based on phase I results, we plan to conduct Phase II/Phase III studies in breast, ovarian, or prostate cancer patients with BRCA mutations.