Introduction: Durvalumab improves survival when used as consolidation therapy after chemoradiation (CRT) in patients with stage III NSCLC. The optimal consolidation therapy for patients with EGFR-mutant (EGFRmut) stage III NSCLC remains unknown., Methods: In this multi-institutional, international retrospective analysis across 24 institutions, we evaluated outcomes in patients with stage III EGFRmut NSCLC treated with concurrent CRT followed by consolidation therapy with osimertinib, durvalumab, or observation between 2015 and 2022. Kaplan-Meier method was used to estimate real-world progression-free survival (rwPFS, primary end point) and overall survival (secondary end point). Treatment-related adverse events (trAEs) during consolidation treatment were defined using Common Terminology Criteria for Adverse Events version 5.0. Multivariable Cox regression analysis was used., Results: Of 136 patients with stage III EGFRmut NSCLC treated with definitive concurrent CRT, 56 received consolidation durvalumab, 33 received consolidation osimertinib, and 47 was on observation alone. Baseline characteristics were similar across the three cohorts. With a median follow-up of 46 months for the entire cohort, the median duration of treatment was not reached (NR) for osimertinib (interquartile range: NR-NR) and was 5.5 (interquartile range: 2.4-10.8) months with durvalumab. After adjusting for nodal status, stage III A/B/C, and age, patients treated with consolidation osimertinib had significantly longer 24-month rwPFS compared to those treated with durvalumab or in the observation cohorts (osimertinib: 86%, durvalumab: 30%, observation: 27%, p < 0.001 for both comparisons). There was no difference in rwPFS between the durvalumab and the observation cohorts. No significant difference in overall survival across the three cohorts was detected, likely due to the limited follow-up. Any-grade trAE occurred in 52% (2 [6.1%] grade ≥3) and 48% (10 [18%] grade ≥3) of patients treated with osimertinib and durvalumab, respectively. Of 45 patients who progressed on consolidation durvalumab, 37 (82%) subsequently received EGFR tyrosine kinase inhibitors. Of these, 14 (38%) patients developed trAEs including five patients with pneumonitis (14%; 2 [5.4%] grade ≥3) and five patients with diarrhea (14%; 1 [2.7%] grade ≥3)., Conclusions: This study suggests that among patients with stage III unresectable NSCLC with a sensitizing EGFR mutation, consolidation osimertinib was associated with a significantly longer rwPFS compared to durvalumab or observation. No unanticipated safety signals were observed with consolidation osimertinib., Competing Interests: Disclosure Dr. Nassar receives honoraria from OncLive, TEMPUS, and Korean Society for Medical Oncology and consulting fees from Guidepoint Global. Dr. Kim is on the advisory board for Amgen. Dr. Shepherd reports having stock and other ownership interests from Eli Lilly and AstraZeneca; receiving honoraria from AstraZeneca, Merck Serono, Takeda, and Daiichi Sankyo; having consulting/advisory role at AstraZeneca and Merck Serono; and receiving research funding from Eli Lilly (inst), Pfizer (inst), Bristol-Myers Squibb (inst), AstraZeneca/MedImmune (inst), and Roche Canada (inst). Dr. Gray reports receiving grants from AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, Genentech, G1 Therapeutics, Ludwig Institute of Cancer Research, Merck & Co., Inc., Novartis, and Pfizer; receiving consulting fees from AbbVie, AstraZeneca, Blueprint Medicines, EMD Serono, Gilead Sciences, Inc., Janssen Scientific Affairs, LLC, Jazz Pharmaceuticals, Loxo Oncology Inc., Merck & Co., Inc., Novartis, OncoCyte Biotechnology, Spectrum ODAC, Takeda Pharmaceuticals, and Triptych Health Partners; and having leadership role as SWOG Lung Committee Chair, IASLC Board of Director member, and ASCO Education Committee Ex-Chair. Dr. Dilling reports receiving consulting fees from AstraZeneca and support for travel from NCCN. Dr. Neal reports receiving grants from Genentech/Roche, Merck, Novartis, Boehringer Ingelheim, Exelixis, Nektar Therapeutics, Takeda Pharmaceuticals, Adaptimmune, GlaxoSmithKline, Janssen, AbbVie, and Novocure; receiving consulting fees from AstraZeneca, Genentech/Roche, Exelixis, Takeda Pharmaceuticals, Eli Lilly and Company, Amgen, Iovance Biotherapeutics, Blueprint Pharmaceuticals, Regeneron Pharmaceuticals, Natera, Sanofi/Regeneron, D2G Oncology, Surface Oncology, Turning Point Therapeutics, Mirati Therapeutics, Gilead Sciences, AbbVie, Summit Therapeutics, Novartis, Novocure, Janssen Oncology, and AnHeart Therapeutics; and receiving honorarium from CME Matters, Clinical Care Options CME, Research to Practice CME, Medscape CME, Biomedical Learning Institute CME, MLI Peerview CME, Prime Oncology CME, Projects in Knowledge CME, Rockpointe CME, MJH Life Sciences CME, Medical Educator Consortium, and HMP Education. Dr. Wakelee reports receiving grants from Arrys Therapeutics Research, AstraZeneca/Medimmune, Bristol-Myers Squibb, Genentech/Roche, Merck, Helsinn, Seagen, and Xcovery; and serving on the advisory board of Mirati (compensated)—ended November 2022, IOBiotech (compensated)—October 2023, Merck (NOT compensated), and Genentech/Roche/Bristol-Myers Squibb/AstraZeneca (NOT compensated). Dr. S.H. Lin reports receiving grants from STCube Pharmaceuticals, Beyond Spring, and Nektar Therapeutics; consulting fees from XRAD Therapeutics; serving on the advisory board of AstraZeneca; having stock/stock options from Apple, Google, Amazon, Tesla, Meta, Rivian, and CreatvMicrotech; and having other support from SEEK Diagnostics (co-founder). Dr. Patil reports receiving grants from Gilead Research Scholars and LUNGevity Foundation Award; consulting fees from AstraZeneca, Boehringer Ingelheim, Bicara, Daiichi, Janssen, Jazz Pharmaceuticals, Mirati Therapeutics, Pfizer, Sanofi, Regeneron, Roche/Genentech, Takeda, Gilead Research Scholars, and LUNGevity Foundation Award; and honorarium from Janssen. Dr. Bar reports receiving grants from Merck Sharp & Dohme, AstraZeneca, Roche, Bristol-Myers Squibb, Takeda, AbbVie, Bayer, Boehringer Ingelheim, and Pfizer; receiving consulting fees from AstraZeneca, Merck Sharp & Dohme, Boehringer Ingelheim, Roche, Bristol-Myers Squibb, Takeda, AbbVie, Pfizer, Bayer, and VBL; and having leadership role from Lung Ambition Consortium, Israel Lung Cancer Group, and IASLC committee. Dr. Marron receives grants from Regeneron, Bristol-Myers Squibb, Merck, Boehringer Ingelheim, NCI, and Cancer Research Institute; and serving on the advisory board of AbbVie, Celldex, and Rockefeller University. Dr. Yu receives grants/contracts from AstraZeneca, Pfizer, Daiichi Cullinan Oncology, Janssen, Novartis, Blueprint med, Black Diamond, and Systimmune and consulting fees from AstraZeneca, Daiichi, Taiho, Takeda, Janssen, Amgen, AbbVie, Novocure, and Ipsen. Dr. Owen receives grants/contracts from Bristol-Myers Squibb, Merck, Palobiofarma, Genentech, Onc.AI, and Pfizer; and travel support from Amgen, AstraZeneca, and Genentech. Rocha receives grants/contracts from SEOM, ESMO Fellowship, and AECC; and travel support from Merck Sharp & Dohme, AstraZeneca, and Bristol-Myers Squibb. Dr. Arriola receives grants/contracts from AstraZeneca and Bristol-Myers Squibb; honorarium from Eli Lilly, AstraZeneca, Roche, Takeda, Merck Sharp & Dohme, Pfizer, Janssen, and Bristol-Myers Squibb; and travel support from AstraZeneca, Roche, and Pfizer. Dr. Cheng receives grants/contracts from AstraZeneca and Genentech; and serving on the advisory board of Janssen, G1 Therapeutics, and AstraZeneca. Dr. Parikh receives consulting fees from Jazz Pharmaceuticals, Guardant Health, and AstraZeneca; and honorarium from MJH Life Sciences. Dr. Harris receives grants/contract from NIH P30CA062203, the UC Irvine Comprehensive Cancer Center using UCI Anti-Cancer Challenge Grant, and ACS Seed Grant 129801-IRG-16-187-13-IRG; and serving on the advisory board of UC Irvine as DSMB member. Dr. Nagasaka receives consulting fees from Caris Life Sciences; honorarium/speaker fees from AstraZeneca, Daiichi, Novartis, EMD Serono self, Pfizer, Eli Lilly, Genentech, Regeneron, Takeda, Janssen, Blueprint, and Mirati; travel support from AnHeart Therapeutics; and stock/stock options from Mbrace Therapeutics. Dr. Valazquez receives grants/contracts from ASCO, American Association for Cancer Research (AACR), LUNGevity, NIA P30AG015272, NCI 5U54CA242646-03 Conquer Cancer and Niarchos Foundation, UCSF Clinical Practice Group, and AAMC; consulting fees from AstraZeneca, Merus, Novocure, and Cadence Communications & Research; and having stock/stock options from Corbus Pharmaceuticals. Dr. J.J. Lin receives grants/contracts from Hengrui Therapeutics, Turning Point Therapeutics, Neon Therapeutics, Relay Therapeutics, Bayer, Elevation Oncology, Roche, Linnaeus Therapeutics, Nuvalent, and Novartis; consulting fees from Genentech, C4 Therapeutics, Blueprint Medicines, Nuvalent, Bayer, Elevation Oncology, Novartis, Mirati Therapeutics, AnHeart Therapeutics, Takeda, CLaiM Therapeutics, Regeneron, Pfizer, Turning Point Therapeutics, Daiichi Sankyo, AstraZeneca, and Merus. Dr. Piotrowska receives grants/contracts from Novartis, Takeda, Spectrum, AstraZeneca, Tesaro/GlaxoSmithKline, Cullinan Oncology, Daiichi Sankyo, AbbVie, Janssen, and Blueprint; consulting fees from Taiho, Janssen, Takeda, AstraZeneca, Cullinan Oncology, C4 Therapeutics, Jazz Pharmaceuticals, and Blueprint; and honorarium from Daiichi Sankyo, Janssen, and Eli Lilly (honoraria for nonpromotional educational events). Dr. Reuss receives grants/contracts from Genentech/Roche, Verastem, Nuvalent, and LUNGevity Foundation; consulting fees from Genentech/Roche, Sanofi/Genzyme, Personalis, Guardant, AstraZeneca, Bristol-Myers Squibb, Arcus, AbbVie, Daiichi Sankyo, Catalym, Seagen, and Gilead; and honorarium from AstraZeneca and Merck. Dr. Baena Espinar receives consulting fees from AstraZeneca, Roche, and Merck Sharp & Dohme; honorarium from AstraZeneca, Roche, and Merck Sharp & Dohme; payment for expert testimony from Roche; and travel support from Roche and Janssen. Leal receives research funding to institution from Pfizer, Advaxis, and Bayer, outside the submitted work. Dr. Mak receives grants/contracts from ViewRay; consulting fees from AstraZeneca, Novartis, and Sio Capital Management; and other support from Founder of HealthAI. Dr. Naqash receives grants/contracts from SWOG Hope Foundation and FDA Broad Agency Contract; serving on the advisory board of JCO Precision Oncology; receiving travel support from SITC/American Association for Cancer Research (AACR)/Conquer Cancer Foundation/BinayTara Foundation and Foundation Med/Caris Life Sciences, and Jazz Pharmaceuticals; and funding to institution for trials from Loxo@Lilly, Surface Oncology, ADC Therapeutics, IGM Biosciences, EMD Serono, Aravive, Nikang Therapeutics, Inspirna, Exelexis, Revolution Medicine, Jacobio, Pionyr, Jazz Pharmaceuticals, NGM Biopharmaceuticals, Immunophotonics, and Selexine. Dr. Goldberg receives grants/contracts from AstraZeneca, Boehringer Ingelheim, and Mirati; and serving on the advisory board of AstraZeneca, Bristol-Myers Squibb, Amgen, Sanofi, Genzyme, Daiichi Sankyo, Regeneron, Takeda, Janssen, Summit, and Merck. The remaining authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)