LAUSR

The inevitable development of clinical drug resistance presents a common challenge for targeted cancer therapy. In non-small cell lung cancer (NSCLC) patients with ALK and ROS1 rearrangements, the emergence of mutations in the targeted oncogenes was identified as one of the mechanisms that confer drug resistance. In particular, a group of mutations known as solvent front mutations, such as ALKG1202R and ROS1G2032R, render common resistance to ALK and ROS1 inhibitors. Similar solvent front mutations, such as TRKAG595R and TRKCG623R, have also been identified in cancer patients with rearrangement of NTRK family genes who developed resistance to TRK-targeted therapies. TPX-0005, a compact three-dimensional macrocyclic molecule, was designed to completely locate at the adenine binding site of ATP in order to efficiently target the active kinase conformation and systematically circumvent the steric interference from various clinical resistant mutations, especially the solvent front mutations. TPX-0005 is an orally available and potent ATP-competitive inhibitor against ALK, ROS1, TRKA, TRKB and TRKC recombinant kinases and their corresponding clinical resistant mutants. TPX-0005 demonstrated potent anti-proliferative activity in the range of sub-nanomolar to low nanomolar in a number of human cancer cell lines and engineered stable cell lines expressing the targeted oncogenes or their solvent front mutants, accompanied by inhibition of target phosphorylation and concomitant inactivation of downstream effectors such as ERK, AKT and STAT3. In patient derived xenograft tumor models, TPX-0005 treatment resulted in significant regression of tumors harboring the oncogenic ALK, ROS1 and TRKC fusions. Moreover, in a series of mouse xenograft tumor models, TPX-0005 exhibited marked anti-tumor activity not only in tumors harboring the wildtype oncogenic targets but also in tumors harboring the oncogenes with the solvent front mutations via inhibition of the target phosphorylation. Taken together, these pre-clinical studies have demonstrated the potent activities of TPX-0005 against not only wild type oncogenic ALK, ROS1, TRK fusions but also their corresponding solvent front mutations, which will bring in a new therapy for cancer patients resistant to currently available ALK, ROS1, and TRK inhibitors in clinic. Citation Format: Wei Deng, John Huang, Dayong Zhai, Evan Rogers, Jean Cui. Overcoming acquired drug resistance by TPX-0005, an ALK, ROS1 and pan-TRK inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3168. doi:10.1158/1538-7445.AM2017-3168