Abstract 187: ASN0007, a potent ERK1/2 inhibitor with strong antitumor activity in multiple RAS mutant models

Abstract

Abstract The extracellular-signal-regulated kinases, ERK1 and ERK2 (ERK1/2), play a critical role in the RAS/RAF/MEK signaling pathway which is quite frequently activated by mutations in upstream targets such as BRAF, RAS and receptor tyrosine kinases. Most of the resistance mechanisms to BRAF and MEK inhibitors ultimately lead to increase in phosphorylation of ERK1/2 suggesting the importance of this node in the RAS/RAF/MEK pathway even in the resistance setting. Therefore, inhibition of ERK1/2 offers a promising strategy to address both innate and acquired resistance to BRAF and MEK inhibitors in various solid tumors. In order to inhibit this critical node of the RAS/RAF/MEK pathway, we discovered and characterized ASN007, a novel compound that shows potent inhibition of ERK1/2 kinases in a biochemical assay with low single-digit IC50 values. In mechanistic cell-based assays, ASN007 inhibited the phosphorylation of ERK1/2 substrates such as pRSK1, FRA1 and Elk1 in various cell lines. As expected, the compound did not have any effect on the phosphorylation of ERK1/2. ASN007 showed strong anti-proliferative activity in both BRAF and RAS mutant cell lines. Importantly, when compared to other ERK1/2 inhibitors such as BVD-523 and GDC-0994, ASN007 showed potent antiproliferative activity in a much broader panel of KRAS, NRAS and HRAS mutant cell lines representing various histological tumor types. The compound also caused cell cycle arrest at the G0-G1 phase and induced apoptosis in both BRAF and RAS mutant cell lines. In a daily oral dosing regimen, ASN007 demonstrated strong inhibition of tumor growth in multiple BRAF and KRAS mutant xenograft models in mice and was well tolerated at efficacious doses. ASN007 has a good pharmacokinetic profile in pre-clinical species and does not exhibit significant inhibition of CYP enzymes or hERG channel. Based on its profile in preclinical studies, ASN007 is expected to show strong efficacy in BRAF and RAS mutant cancers. ASN007 is currently in preclinical development. Citation Format: Sanjeeva P. Reddy, Dhanalakshmi Sivanandhan, Raghava Reddy Kethiri, Sreekala Nair, Purushottam Dewang, Mohd Zainuddin, Krishnakumar Vaithilingam, Roger A. Smith, Sandeep Gupta, Scott K. Thompson. ASN0007, a potent ERK1/2 inhibitor with strong antitumor activity in multiple RAS mutant models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 187.