Phase 1b study of HS-10241 combined with almonertinib in pre-treated advanced nonsmall cell lung cancer (NSCLC) harboring EGFR mutation

e21134 Background: MET gene amplification is one of the most frequent acquired resistance mechanisms following prior EGFR-TKI monotherapy. HS-10241, an oral and highly selective MET-TKI, may contribute to overcoming common acquired MET-based resistance mechanisms. Here, we reported the preliminary safety and efficacy data of HS-10241 with almonertinib in treatment of advanced NSCLC with EGFR mutation. Methods: This Ph1b study (NCT05430386) was composed of dose escalation part (Part 1) and dose expansion part (Part 2). In Part 1, patients (pts) with EGFR-mutated advanced NSCLC upon disease progression on EGFR-TKI received HS-10241 (BID) plus almonertinib (110 mg QD), and HS-10241 was escalated at 200 mg and 300 mg using a rolling six design. Based on the available data of Part 1, an expansion cohort was opened at HS-10241 300 mg BID with almonertinib 110mg QD to enroll pts with EGFR mutation centrally confirmed and MET-amplification detected by central FISH (MET gene copy number[GCN] ≥5 and/or MET:CEP7 signal ratio ≥2). Results: As of 16 December 2022, 10 pts in part 1, 4 pts at 200 mg and 6 pts at 300 mg HS-10241, and 35 pts in part 2 were enrolled into this study. Of these pts, 13 (28.9%) pts received previous treatment with 1st or 2nd-generation but no 3rd-generation EGFR TKI, 15 (33.3%) pts received 3rd-generation EGFR-TKI only and 15 (33.3%) pts received both 1st/2nd and 3rd-generation EGFR TKIs, whether or not they received treatment with chemotherapy. Only one dose-limiting toxicity (grade 2 Nausea with grade 2 vomiting leading to discontinuation≥14 days) was reported in the cohort with HS-10241 300 mg. The MTD was not reached. Treatment-emergent adverse events (TEAEs) occurred in 41/45 (91.1%) pts. The most common TEAEs (≥ 20%) were increased AST, increased ALT, vomiting, nausea, increased blood creatine phosphokinase, thrombocytopenia, decreased appetite, and increased GGT. Among all the pts, 22 pts with EGFR mutation regardless of the MET gene status were evaluable for efficacy, 12 of which achieved partial response (response rate 54.5%; 8 confirmed PR), and 7 had stable disease (SD). Of the 13 pts who had centrally confirmed EGFR mutation and MET-amplification (6 with GCN ≥10, and 7 with GCN ≥5 but < 10), 8 had PR (response rate 61.5%; 5 confirmed PR), and 4 had SD. Among the 8 pts achieving PR, there were 4 with GCN ≥10, and 4 with GCN ≥5 but < 10.Moreover, 9 of the 13 pts received both 1st/2nd and 3rd-generation EGFR-TKI and there were 6 PRs (response rate 66.7%;3 confirmed PR) and 2 SDs. Pharmacokinetics analysis showed low risk of potential drug-drug interactions on HS-10241 combined with almonertinib. Conclusions: HS-10241 in combination with almonertinib was well tolerated, and showed encouraging antitumor activity in treatment of advanced NSCLC with EGFR mutation and MET amplification following prior EGFR-TKI, whether MET GCN ≥10 or MET GCN ≥5 but < 10. Clinical trial information: NCT05430386 .