Background: Patients with EGFR-mutated non-small-cell lung cancer (NSCLC) and MET amplification as a mechanism of resistance to first-line osimertinib have few treatment options. Here, we report the primary analysis of the phase 2 INSIGHT 2 study evaluating tepotinib, a highly selective MET inhibitor, combined with osimertinib in this population., Methods: This open-label, phase 2 study was conducted at 179 academic centres and community clinics in 17 countries. Eligible patients were aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0 or 1 and advanced or metastatic EGFR-mutated NSCLC of any histology, with MET amplification by tissue biopsy fluorescence in-situ hybridisation (FISH; MET gene copy number of ≥5 or MET-to-CEP7 ratio of ≥2) or liquid biopsy next-generation sequencing (MET plasma gene copy number of ≥2·3), following progression on first-line osimertinib. Patients received oral tepotinib 500 mg plus oral osimertinib 80 mg once daily. The primary endpoint was independently assessed objective response in patients with MET amplification by central FISH treated with tepotinib plus osimertinib with at least 9 months of follow-up. Safety was analysed in patients who received at least one study drug dose. This study is registered with ClinicalTrials.gov, NCT03940703 (enrolment complete)., Findings: Between Feb 13, 2020, and Nov 4, 2022, 128 patients (74 [58%] female, 54 [42%] male) were enrolled and initiated tepotinib plus osimertinib. The primary activity analysis population included 98 patients with MET amplification confirmed by central FISH, previous first-line osimertinib and at least 9 months of follow-up (median 12·7 months [IQR 9·9-20·3]). The confirmed objective response rate was 50·0% (95% CI 39·7-60·3; 49 of 98 patients). The most common treatment-related grade 3 or worse adverse events were peripheral oedema (six [5%] of 128 patients), decreased appetite (five [4%]), prolonged electrocardiogram QT interval (five [4%]), and pneumonitis (four [3%]). Serious treatment-related adverse events were reported in 16 (13%) patients. Deaths of four (3%) patients were assessed as potentially related to either trial drug by the investigator due to pneumonitis (two [2%] patients), decreased platelet count (one [1%]), respiratory failure (one [1%]), and dyspnoea (one [1%]); one death was attributed to both pneumonitis and dyspnoea., Interpretation: Tepotinib plus osimertinib showed promising activity and acceptable safety in patients with EGFR-mutated NSCLC and MET amplification as a mechanism of resistance to first-line osimertinib, suggesting a potential chemotherapy-sparing oral targeted therapy option that should be further investigated., Funding: Merck (CrossRef Funder ID: 10.13039/100009945)., Competing Interests: Declaration of interests Y-LW reports receiving institute grants from AstraZeneca, Bristol Myers Squibb, and Pfizer; consulting fees from AstraZeneca, Boehringer Ingelheim, Merck, and Roche; and speaker fees from AstraZeneca, Eli Lilly, Hengrui, Pfizer, Roche, and Sanofi. VG reports receiving personal fees for advisory board membership from AstraZeneca, Daiichi Sankyo, Eisai, Eli Lilly, Exact Sciences, Gilead, MSD, Novartis, Pfizer, and Olema Oncology; speaker fees from Amgen, AstraZeneca, Eli Lilly, Exact Sciences, Gilead, GSK, and Novartis; fees for expert testimony for Eli Lilly; and travel support from Gilead, AstraZeneca, and PharmaMar. PJV reports receiving personal fees for advisory board membership from Amgen, AstraZeneca, BeiGene, Ipsen, MSD, Novartis, Pfizer, and Roche. MWi reports receiving personal advisory board fees, consulting fees, speaker fees, and institute grants from AstraZeneca. CKL reports receiving research grants from AstraZeneca and Boehringer Ingelheim; honoraria for lectures from AstraZeneca, Boehringer Ingelheim, Janssen, MSD, Novartis, Pfizer, Roche, and Zuellig Pharma; travel support from AstraZeneca, Boehringer Ingelheim, Merck, MSD, Novartis, Pfizer, and Roche; and personal fees for advisory board membership from AstraZeneca, Janssen, MSD, Novartis, Pfizer, and Roche. JM reports receiving advisory board fees from Roche, Bristol Myers Squibb, AstraZeneca, Pfizer, Novartis, Merck, Daiichi Sankyo, and MSD, and research funding to his institution from Roche, AstraZeneca, and Pierre Fabre. LMT reports receiving advisory board fees from AstraZeneca, Janssen, Merck, Novartis, Pfizer, and Roche; personal honoraria fees from AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Janssen, Merck, Novartis, Pfizer, and Roche; and travel support from AstraZeneca, Merck, Novartis, Pfizer, and Roche. HH reports receiving honoraria fees from AstraZeneca, Ono Pharmaceutical, Bristol Myers Squibb, Eli Lilly, Boehringer Ingelheim, Sysmex Corporation, 3H Medi Solution, Chugai Pharmaceutical, Pfizer, Novartis, Merck Biopharma Co, Tokyo, Japan, an affiliate of Merck, Amgen, Daiichi Sankyo/UCB Japan, Takeda, and MSD; research funding from IQVIA, Syneos Health Clinical, EPS Corporation, Nippon Kayaku, Takeda, MSD, Amgen, Taiho Pharmaceutical, Bristol Myers Squibb, Janssen, CMIC, Pfizer R&D, LabCorp, Kobayashi Pharmaceutical, Pfizer, Eisai, EP-CRSU, Shionogi & Co, Otsuka Pharmaceutical, GSK, Sanofi, Chugai Pharmaceutical, Boehringer Ingelheim, SRL Medisearch, PRA Health Sciences, Astellas Pharma, Ascent Development Services, and Bayer; and financial support for the present manuscript from Guardant Health. PLC reports receiving advisory board fees from AstraZeneca, Merck, and Pfizer, and honoraria fees from AstraZeneca. JR reports receiving personal honoraria from Bristol Myers Squibb, speaker fees (to their institution) from Merck, and advisory board fees (to their institution) from Merck. GF reports receiving personal fees for speaker engagements with AstraZeneca, Bristol Myers Squibb, and MSD, and travel support from Roche. TK reports receiving honoraria from Amgen, AstraZeneca, BeiGene, Boehringer Ingelheim, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, GlaxoSmithKline, Janssen, Merck, MSD, Novartis, Ono Pharmaceutical, Pfizer, Taiho, and Takeda; receiving research funding for their institution from AbbVie, Amgen, AstraZeneca, BeiGene, BluePrint, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, Haihe Biopharma, Merck, MSD, Novartis, Pfizer, Regeneron, Takeda, and TurningPoint; receiving advisory board fees from AstraZeneca, BeiGene, Daiichi Sankyo, Janssen, Merck, MSD, Novartis, and Pfizer; and their spouse as an employee of Eli Lilly. EN reports receiving research funding from Roche, Pfizer, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, and Bristol Myers Squibb; consulting fees from Roche, Bristol Myers Squibb, MSD, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, Sanofi, Pfizer, Eli Lilly, Amgen, Janssen, Daiichi Sankyo, Boehringer Ingelheim, AstraZeneca, Takeda, Sanofi, Janssen, Pierre Fabre, Qiagen, and Bayer; personal honoraria for lectures from Roche, Bristol Myers Squibb, MSD, Sanofi, Pfizer, Eli Lilly, Amgen, Janssen, Boehringer Ingelheim, AstraZeneca, Takeda, Sanofi, Janssen, Qiagen, Mirati, and Bayer; travel support from Takeda, MSD, AstraZeneca, and Roche; and fees for participation in data safety meetings from Apollomics. HSH reports receiving research grants for their institution from AstraZeneca, Merck, Janssen, Novartis, and Boehringer Ingelheim; honoraria and fees for lectures and advisory board meetings from AstraZeneca, MSD, Novartis, Pfizer, Roche, and Janssen; and travel support from AstraZeneca, Boehringer Ingelheim, MSD, Novartis, Pfizer, and Roche. EFS reports receiving advisory or consultancy fees to their institution from Eli Lilly, AstraZeneca, MSD, Boehringer Ingelheim, Bristol Myers Squibb, Takeda, and Daiichi Sankyo; personal speaker fees from Boehringer Ingelheim; and advisory board fees from Merck and Daiichi Sankyo. MWe reports holding a consulting or advisory role for Bristol Myers Squibb, Novartis, Eli Lilly, Boehringer Ingelheim, ISA Pharmaceuticals, Amgen, Immatics, Bayer, and ImCheck therapeutics; honoraria fees from Eli Lilly, Boehringer Ingelheim, SYNLAB, Janssen, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, GWT, Amgen, and Novartis; travel support from Pfizer, Bristol Myers Squibb, AstraZeneca, Amgen, GEMoaB, Sanofi/Aventis, Immatics, and EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck; and research funding to his institution from Roche. DT reports receiving consulting fees for their institution from Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, DKSH, GSK, Merck, Novartis, Roche, Pfizer, and Takeda; research funding from ACM Biolabs, Amgen, AstraZeneca, Bayer, and Pfizer; and speaker fees for their institution from Amgen, Bayer, Merck, Pfizer, Novartis, Boehringer Ingelheim, Roche, and Takeda. MM reports receiving research funding from Boehringer Ingelheim and Eli Lilly; personal honoraria fees from Boehringer Ingelheim, Daiichi Sankyo, AstraZeneca, Pfizer, Eli Lilly, Chugai Pharmaceutical, MSD, Ono Pharmaceutical, and Taiho Pharmaceutical; and other clinical trial support from Chugai Pharmaceutical, AstraZeneca, Ono Pharmaceutical, Pfizer, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, Kissei, Taiho, and Novartis. AO’B, SA, BMP, CS, DJ, RS, BE-L, and NK report being employees of Merck. KB reports being an employee of Merck at the time of the study and manuscript preparation. KG reports being an employee of EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck. XL reports receiving consulting fees from EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, AstraZeneca, Spectrum Pharmaceuticals, Novartis, Eli Lilly, Boehringer Ingelheim, Hengrui Therapeutics, Janssen Oncology, Daiichi Sankyo, Blueprint Medicines, Sensei Biotherapeutics, AbbVie, Arrivent, and Regeneron; travel support from Spectrum Pharmaceuticals and EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, and research funding to their institution from Eli Lilly, Boehringer Ingelheim, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, and Regeneron. TMK reports receiving grants for their institution from AstraZeneca; consulting fees from AstraZeneca, Janssen, Regeneron, Samsung Bioepis, Takeda, and Yuhan; honoraria for lectures from AstraZeneca, IMBDx, Janssen, Takeda, and Yuhan; advisory board fees from AstraZeneca, Janssen, Regeneron, and Takeda; and clinical trial funding to their institution from AbbVie, Amgen, AstraZeneca/Medimmune, Bayer, Black Diamond Therapeutics, Blueprint Medicines, Boryung, Bristol Myers Squibb, Celgene, Dizal, EMD Serono Research & Development Institute, Billerica, MA, USA, an affiliate of Merck, Roche/Genentech, Hanmi, Genmab, Janssen, Novartis, RAPT Therapeutics, Regeneron, Sanofi, Takeda, and Yuhan. All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)