Abstract 5226: TPX-0131: A next generation macrocyclic ALK inhibitor that overcomes ALK resistant mutations refractory to current approved ALK inhibitors

Abstract

Anaplastic lymphoma kinase (ALK) gene rearrangements occur in up to 7% of patients with non-small cell lung cancer (NSCLC) with the majority as EML4-ALK fusions. Crizotinib (first generation ALK inhibitor) was the first approved ALK inhibitor for the treatment of ALK-positive metastatic non-small cell lung cancer. However, development of resistance to crizotinib caused by secondary kinase domain mutations, bypass signaling, or morphology changes occurs. Second generation ALK inhibitors alectinib, ceritinib, and brigatinib were able to overcome the majority of ALK resistant mutations (L1196M, G1269A and F1174L) acquired with crizotinib. The solvent front mutation (SFM) G1202R is a common resistant mutation to crizotinib and the second generation ALK inhibitors. Lorlatinib, a third generation ALK inhibitor, can overcome G1202R resistance with moderate IC50 values of 40 - 60 nM in cell-based assays. Although, compound mutations such as ones with both gatekeeper and solvent front mutations (L1196M/G1202R) are refractory to lorlatinib, representing an unmet medical need. TPX-0131 is a next generation ALK inhibitor designed with a compact macrocyclic structure that can bind completely within the ATP binding boundary to overcome a variety of ALK resistant mutations, especially SFM G1202R and compound mutations L1196M/G1202R. TPX-0131 potently inhibits wildtype (WT) ALK and over 20 different ALK mutations with IC50 values <5 nM when tested in enzymatic kinase assays in the presence of 10 μM of ATP. In cell proliferation assays, TPX-0131 exhibited comparable antiproliferation activity to the most potent ALK inhibitor lorlatinib in Ba/F3 cells engineered with EML4-ALK WT. Importantly, TPX-0131 is more than 100-fold more potent against G1202R than lorlatinib in cell proliferation assays. Furthermore, TPX-0131 demonstrated antiproliferation IC50 values <2 nM in Ba/F3 cell models engineered with compound mutations including L1196M/G1202R, L1198F/G1202R, L1196M/L1198F, and C1156Y/G1202R, while lorlatinib and other ALK inhibitors are not active (IC50s >1 μM). Taken together, TPX-0131 is a next generation ALK inhibitor that can overcome a broad spectrum of acquired resistance mutations, especially the G1202R solvent front mutation and compound mutations (e.g. L1196M/G1202R). The nonclinical pharmacology profile of TPX-0131 warrants further preclinical investigation. Citation Format: J. Jean Cui, Evan Rogers, Dayong Zhai, Wei Deng, Jane Ung, Vivian Nguyen, Han Zhang, Xin Zhang, Ana Parra, Maria Barrera, Dong Lee, Brion Murray. TPX-0131: A next generation macrocyclic ALK inhibitor that overcomes ALK resistant mutations refractory to current approved ALK inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5226.

Going beneath the tip of the iceberg. Identifying and understanding EML4-ALK variants and TP53 mutations to optimize treatment of ALK fusion positive (ALK+) NSCLC

“…regardless of EML4-ALK variants[53], however there is on-going vigorous debate whether lorlatinib should be the preferred first-line treatment of advanced ALK+ NSCLC[54] Translational data from likely further analysis of the CROWN trial may eventually bear out our recommendations. Upon progression due to on-target resistance, such as the acquired ALK resistance mutations, the next optimal ALK TKI will depend on the mutations and potential clinical trials of fourth-generation ALK TKIs such as TPX-0131 and NUV-655[55][56][57]. For progression due to off-target resistance mechanisms, a combination of an HSP90 inhibitor and an ALK TKI to attack…”

A Novel Sequentially Evolved EML4-ALK Variant 3 G1202R/S1206Y Double Mutation In Cis Confers Resistance to Lorlatinib: A Brief Report and Literature Review

“…Currently, a fourthgeneration ALK TKI, TPX-0131, designed to overcome many of the aforementioned ALK double mutations, could potentially be the next treatment strategy for this patient when it is available for clinical trial. 19 Recently, in a randomized phase 3 trial (CROWN), lorlatinib compared with crizotinib achieved an impressive blinded independent review committee (BIRC)-assessed hazard ratio (HR) of 0.28 (95% confidence interval [CI]: 0.19-0.41) for PFS in all patients, HR (C) ALK G1202R residue in the less preferred conformation with minimized steric hindrance to lorlatinib. In this "pulled forward" conformation, the basic ALK G1202R will interact with the acidic ALK E1210 residue and form a ALK D1203-S1206-E1210-G1202R quaternary complex with ALK D1203 and ALK S1206.…”

Actionability of on-target ALK Resistance Mutations in Patients With Non-Small Cell Lung Cancer: Local Experience and Review of the Literature

“…This is illustrated by L1196M and G1202R, which are individually sensitive to lorlatinib and thus confer sensitivity when detected in different subclones, but demonstrate high-level of resistance when present in the same subclone. 24 Selective ALK inhibitors targeting these lorlatinibresistant compound mutations, such as NUV-655 30 , and TPX-0131 31 , are currently under development, but not yet available for use in patients. When mutations are detected in trans, they are more likely to represent multiple clones that may individually be sensitive as single mutants with the same inhibitor and may co-targeted with combination therapy.…”