ROS1 G2032R

The FDA-approved tyrosine kinase inhibitors (TKIs) crizotinib and entrectinib have demonstrated efficacy in treating ROS1 fusion-positive NSCLC. These findings underscore the potential of repotrectinib to address unmet needs in ROS1-rearranged NSCLC, offering durable responses and improved intracranial activity. Future research should prioritize developing next-generation, selective ROS1 inhibitors to reduce Trk-mediated toxicities and improve treatment tolerance.

In this study we knock-in for the first time in a ROS1 + patient-derived cell line, three different known resistance-causing mutations using CRISPR/Cas9 in the endogenous translocated ROS1 alleles. Pharmacological assays performed in 2D and 3D cell culture revealed that spheroids are more sensitive to TKIs than cells cultured as a monolayer. This direct comparison between two culture systems could be done thanks to the implementation of normalized growth rates (NGR) to uniformly quantify drug response between 2D and 3D cell culture. Overall, this study presents the added value of using spheroids and positions lorlatinib and repotrectinib as the most effective TKIs against the studied ROS1 resistance point mutations.

This study provided a comprehensive portrait of TKI-resistance mechanisms in ROS1+ NSCLC patients. Using in silico simulations of TKI activity, novel secondary mutations that may confer TKI resistance were identified and may support clinical therapeutic decision-making.

These findings confirm crizotinib's sustained clinical efficacy and safety in a real-world context, which was characterized by a higher elderly population and higher rates of brain/CNS metastases. The study highlights the clinical relevance of liquid biopsy for detecting resistance mechanisms, suggesting its value in personalized treatment strategies.

Repotrectinib had durable clinical activity in patients with ROS1 fusion-positive NSCLC, regardless of whether they had previously received a ROS1 TKI. Adverse events were mainly of low grade and compatible with long-term administration. (Funded by Turning Point Therapeutics, a wholly owned subsidiary of Bristol Myers Squibb; TRIDENT-1 ClinicalTrials.gov number, NCT03093116.).

Despite ROS1 fusion positive (ROS1+) NSCLC accounting approximately 1-2% of NSCLC, there is a dizzying list of ROS1 tyrosine kinase inhibitor (TKIs) being developed in addition to two approved ROS1 TKIs, crizotinib and entrectinib...Additionally, the less known central β-sheet 6 (Cβ6) mutation ROS1 L2086F confer resistances to next-generation ROS1 TKIs (taletrectinib, lorlatinib, potentially NVL-520) that can be overcome by cabozantinib as documented in published patient reports and may potentially by certain L-shaped Type I ROS1 TKIs including gilteritinib which is approved as a FLT3 inhibitor for AML. Future clinical trials should investigate cabozantinib and gilteritinib to repurpose them as ROS1 TKIs that can target Cβ6 mutation.

In line with its activity, we documented the presence of the drug at potentially active concentrations in the cerebrospinal fluid. Nevertheless, the short-lived response reported by our patient highlights the importance for novel ROS1-tyrosine kinase inhibitors (TKIs) to be specifically developed to be able to penetrate the blood-brain barrier.

No treatment-related AE (TRAE) led to discontinuation or death; 24% of pts had a TRAE leading to dose reduction. Conclusions In this ongoing global pivotal phase 2 study, taletrectinib demonstrated robust and consistent clinical activity with TRUST-I, including high response rates and a tolerable safety profile in both TKI-naive and TKI-pretreated pts with ROS1+ NSCLC.

With 14 months' minimum follow-up in TRIDENT-1, repotrectinib continued to demonstrate durable efficacy in patients with ROS1+ NSCLC, including intracranial activity, in both TKI-naïve and 1 prior TKI and no chemo cohorts. Safety in patients treated at RP2D was manageable, consistent with previous reports in all treated patients.

Osimertinib-resistant YU-1097 harboring EGFR resistance mutation (E19del/T790M/C797S) revealed sensitivity to BLU-945 (IC50, 108nM), a novel fourth-generation EGFR-TKI. A similar inhibition of cell viability was observed with repotrectinib (IC50, 21nM), a next-generation ROS1-TKI and lorlatinib (IC50, 9nM) in YU-1078 harboring CD74-ROS1, whereas more robust tumor regression was seen with repotrectinib in YU1078-derived xenograft model. Amivantamab, a EGFR-MET bispecific antibody, showed a robust activity in YU-1163 and YUO-036 in vitro and in vivo. PDC/PDO models can be utilized for evaluating activity of novel agents and will accelerate novel drug development in NSCLC.

Results G2032R line showed in 2D the strongest resistance towards crizotinib, entrectinib and ceritinib, having all a weak activity (IC50 s around 1,1 μM), opposed to repotrectinib (93,25 nM) and lorlatinib (317,17 nM). These results were confirmed by western blot. Our approach allows the generation of patient-derived mutant cell lines and screened for TKI sensitivity guided by the in silico modelling of ROS1 variants.