Abstract 4796: Ropotrectinib is a novel polypharmacology kinase inhibitor against WT and mutant ROS1, TRK and ALK
Authors: Deng Wei , Zhai Dayong , Huang John , Rogers Evan , Whitten Jeffrey , Lim John , Li Yishan , Cui Jean 
Published: August 2018

Tyrosine kinase inhibitors (TKI) have achieved great success for cancer patients with aberrant target genes such as ROS1, NTRKs and ALK. However, the inevitable emergence of drug resistance limits their long-term clinical benefits. Ropotrectinib (TPX-0005), a brain-tumor penetrable ROS1/TRK/ALK kinase inhibitor, was designed not only to target abnormal activity of ROS1, TRK and ALK but also to overcome drug resistance caused by previous ROS1, NTRK and ALK inhibitors. The unique structure design of roporectinib granted it the unique ability to overcome acquired solvent front mutations in the targeted kinase domain caused by other TKIs. Moreover, ropotrectinib displays inhibitory activity for SRC/FAK/JAK2, rendering its potential to overcome drug resistance caused by “by-passing” mechanisms such as EMT.

Ropotrectinib is a superb ROS1 inhibitor. The ALK/ROS1/MET inhibitor crizotinib has been approved by FDA to treat NSCLC patients harboring a rearranged ROS1 fusion gene. Acquired secondary mutations in ROS1 kinase domain is a common drug resistance mechanism in 50-60% patients progressed on crizotinib treatment, with solvent front mutations most frequently observed. Compared to other ROS1 inhibitors, such as lorlatinib, ceritinib, brigatinib and entrectinib, ropotrectinb demonstrated most potent activity against WT and mutant ROS1, especially solvent front mutations such as G2032R in cellular assays and potently inhibited xenograft tumors.

Ropotrectinib is the most potent TRK inhibitors in clinic, with IC50s &lt; 1nM in cellular assays. Preclinic in vitro and in vivo studies further demonstrated that ropotrectinib overcomes clinical resistance mutations which occur in patients progressed on TRK inhibitors, such as entrectinib and larotrectinib. In a phosphorylation assay using engineered NIH3T3 cells expressing a TRKAG595R fusion gene, ropotrectinib (IC50 &lt; 0.1nM) exhibited activities at least ten folds more potent than the recently reported activity of LOXO-195 (IC50 = 7nM), a second generation of TRK inhibitor in clinic.

Ropotrectinib is also a ALK inhibitor with CNS activity, inhibiting growth and viability of ALK+ cells, inducing tumor regression in a ALK+ PDX tumor model and significantly improving overall survival of mice bearing CNS ALK+ H2228 tumors. In particular, compared to previous generations of ALK inhibitors (e.g. crizontinib, ceritinib, alectinib, and brigatinib), it exhibited superb activity in those acquired mutations, especially the G1202R solvent front mutation and double mutations containing L1198F. Roporectinib dose-dependently down-regulated EGFR, CD44 and vimentin expression levels via SRC/FAK inhibition, suggesting a potential to prevent EMT.

In summary, ropotrectinib exerts unique pharmacological properties for clinical applications in patients harboring aberrant ROS1/TRK/ALK. A Phase 1/2 clinical trial of TPX-0005 is actively pursued (NCT03093116).

Citation Format: Wei Deng, Dayong Zhai, John Huang, Evan Rogers, Jeffrey Whitten, John Lim, Yishan Li, Jean Cui. Ropotrectinib is a novel polypharmacology kinase inhibitor against WT and mutant ROS1, TRK and ALK [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4796.