Neoadjuvant and adjuvant pembrolizumab plus chemotherapy in locally advanced gastric or gastro-oesophageal cancer (KEYNOTE-585): an interim analysis of the multicentre, double-blind, randomised phase 3 study.

Background: The benefit of combination neoadjuvant and adjuvant chemotherapy and immune checkpoint inhibition in patients with locally advanced, resectable gastric or gastro-oesophageal adenocarcinoma is unknown. We assess the antitumor activity of neoadjuvant and adjuvant pembrolizumab plus chemotherapy in patients with locally advanced resectable gastric or gastro-oesophageal adenocarcinoma.
Methods: The KEYNOTE-585 study is a multicentre, randomised, placebo-controlled, double-blind, phase 3 study done at 143 medical centres in 24 countries. Eligible patients were aged 18 years or older with untreated, locally advanced, resectable gastric or gastro-oesophageal adenocarcinoma, and an Eastern Cooperative Oncology Group performance status 0-1. Patients were randomly assigned (1:1) by an interactive voice response system and integrated web response system to neoadjuvant pembrolizumab 200 mg intravenously or placebo (saline) plus cisplatin-based doublet chemotherapy (main cohort) every 3 weeks for 3 cycles, followed by surgery, adjuvant pembrolizumab or placebo plus chemotherapy for 3 cycles, then adjuvant pembrolizumab or placebo for 11 cycles. A small cohort was also randomly assigned (1:1) to pembrolizumab or placebo plus fluorouracil, docetaxel, and oxaliplatin (FLOT)-based chemotherapy (FLOT cohort) every 2 weeks for four cycles, followed by surgery, adjuvant pembrolizumab, or placebo plus FLOT for four cycles, then adjuvant pembrolizumab or placebo for 11 cycles. Patients were stratified by geographic region, tumour stage, and chemotherapy backbone. Primary endpoints were pathological complete response (reviewed centrally), event-free survival (reviewed by the investigator), and overall survival in the intention-to-treat population, and safety assessed in all patients who received at least one dose of study treatment. The study is registered at ClinicalTrials.gov, NCT03221426, and is closed to accrual.
Findings: Between Oct 9, 2017, and Jan 25, 2021, of 1254 patients screened, 804 were randomly assigned to the main cohort, of whom 402 were assigned to the pembrolizumab plus cisplatin-based chemotherapy group and 402 to the placebo plus cisplatin-based chemotherapy group, and 203 to the FLOT cohort, of whom 100 were assigned to the pembrolizumab plus FLOT group and 103 to placebo plus FLOT group. In the main cohort of 804 participants, 575 (72%) were male and 229 (28%) were female. In the main cohort, after median follow-up of 47·7 months (IQR 38·0-54·8), pembrolizumab was superior to placebo for pathological complete response (52 [12·9%; 95% CI 9·8-16·6] of 402 vs eight [2·0%; 0·9-3·9] of 402; difference 10·9%, 95% CI 7·5 to 14·8; p<0·00001). Median event-free survival was longer with pembrolizumab versus placebo (44·4 months, 95% CI 33·0 to not reached vs 25·3 months, 20·6 to 33·9; hazard ratio [HR] 0·81, 95% CI 0·67 to 0·99; p=0·0198) but did not meet the threshold for statistical significance (p=0·0178). Median overall survival was 60·7 months (95% CI 51·5 to not reached) in the pembrolizumab group versus 58·0 months (41·5 to not reached) in the placebo group (HR 0·90, 95% CI 0·73 to 1·12; p=0·174). Grade 3 or worse adverse events of any cause occurred in 312 (78%) of 399 patients in the pembrolizumab group and 297 (74%) of 400 patients in the placebo group; the most common were nausea (240 [60%] vs 247 [62%]), anaemia (168 [42%] vs 158 [40%]), and decreased appetite (163 [41%] vs 172 [43%]). Treatment-related serious adverse events were reported in 102 (26%) and 97 (24%) patients. Treatment-related adverse events that led to death occurred in four (1%) patients in the pembrolizumab group (interstitial ischaemia, pneumonia, decreased appetite, and acute kidney injury [n=1 each]) and two (<1%) patients in the placebo group (neutropenic sepsis and neutropenic colitis [n=1 each]).
Interpretation: Although neoadjuvant and adjuvant pembrolizumab versus placebo improved the pathological complete response, it did not translate to significant improvement in event-free survival in patients with untreated, locally advanced resectable gastric or gastro-oesophageal cancer.
Funding: Merck Sharp & Dohme.
Competing Interests: Declaration of interests KS reports research funding to their institution from Astellas Pharma, Ono Pharmaceutical, Daiichi Sankyo, Taiho Pharmaceutical, Chugai Pharma, Merck Sharp & Dohme, Amgen, and Eisai, consulting fees from Eli Lilly, Bristol-Myers Squibb, Takeda Pharmaceutical, Novartis, Abbive, Daiichi Sankyo, Taiho Pharmaceutical, GlaxoSmithKline, Amgen, Boehringer Ingelheim, Merck Sharp & Dohme, Astellas, Guardant Health Japan, and Janssen, and honoraria from Bristol-Myers Squibb, Takeda Pharmaceuticals, and Janssen; SYR reports research funding to their institution from Amgen, Astellas, Daiichi Sankyo, Eisai, Merck, Roche, Zymework, Indivumed, Merck Sharp & Dohme, Ono Pharmaceutical, Bristol-Myers Squibb, and AstraZeneca, consultancy fees from Amgen, Astellas, Daiichi Sankyo, Eisai, LG Biochem, Indivumed, Merck Sharp & Dohme, Ono Pharmaceutical, Bristol-Myers Squibb, and AstraZeneca, and fees for speaker bureau from Eli Lilly, Eisai, Daiichi Sankyo, Merck Sharp & Dohme, Ono Pharmaceutical, and Bristol-Myers Squibb; LSW, PY, JX, SA, MO, HYab, Y-KP, TO, and NK report research funding to their institution from Merck Sharp & Dohme; S-EA-B reports research funding to their institution from Celgene, Eli Lilly, Sanofi, German Cancer Aid, German Research Foundation, German Federal Ministry of Education and Research, Roche, Vifor Pharma, Eurozyto, Immutep, Ipsen, Bristol-Myers Squibb, Merck Sharp & Dohme, and AstraZeneca, fees for speakers' bureau participation from Eli Lilly, AIO, Bristol-Myers Squibb, and MCI Group, fees for consulting or advisory role for Bristol-Myers Squibb, Merck Sharp & Dohme, AstraZeneca, Daiichi Sankyo, and Eli Lilly Germany, and stock ownership in Institut fir Klinische Grebsforschung and Immutep; TY reports honoraria from Merck Sharp & Dohme, Ono Pharmaceutical, Bristol-Myers Squibb, Daiichi-Sankyo, AstraZeneca, TREUMO, Otsuka, Covidien, Johnson & Johnson, Olympus, and Intuitive; HYas reports research funding to their institution from Merck Sharp & Dohme, and honoraria from Chugai Pharma; MDB reports research funding to their institution from Merck Sharp & Dohme, honoraria from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Eli Lilly, and Servier, reimbursement for travel from Daiichi, and participation on an advisory board for Novartis; SL reports research funding to their institution from Amgen, Astellas, AstraZeneca, Bayer, Bristol-Myers Squibb, Daichii Sankyo, Hutchinson, Incyte, Merck Serono, Mirati, Merck Sharp & Dohme, Pfizer, Roche, and Servier, consulting fees from Amgen, AstraZeneca, Bristol-Myers Squibb, Daichii Sankyo, Incyte, Eli Lilly, Merck Serono, Merck Sharp & Dohme, Servier, and Astellas, and honoraria from Amgen, Bristol-Myers Squibb, Incyte, GlaxoSmithKline, Eli Lilly, Merck Serono, Merck Sharp & Dohme, Pierre-Fabre, Roche, Servier; JT reports consulting fees from Array Biopharma, AstraZeneca, Bayer, Boehringer Ingelheim, Cardiff Oncology, Chugai, Daiichi Sankyo, F Hoffman-La Roche, Genentech, HalioDX SAS, Hutchison MediPharma International, Ikena Oncology, Inspira, IQVIA, Eli Lilly, Menarini, Merck Serono, Merus, Merck Sharp & Dohme, Mirati, Neophore, Novartis, Ona Therapeutics, Orion Biotechnology, Peptomyc, Pfizer, Pierre Fabre, Samsung Bioepis, Sanofi, Scandion Oncology, Scorpion Therapeutics, Seattle Genetics, Servier Sotio Biotech, Taiho, Tessa Therapeutics, TheraMyc, and Tolremo Therapeutics, honoraria from HMP, Medscape Education, MJH Life Sciences, PeerView Institute for Medical Education, and Physicians Education Resource, and stock options in Oniria Therapeutics; EVC reports research funding to their institution from Amgen, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Merck Sharp & Dohme, Merck KGaA, Novartis, Roche, and Servier, and fees for advisory board consulting for Abbvie, ALX, Amgen, Array, Astellas, AstraZeneca, Bayer, Beigene, Boehringer Ingelheim, Bristol Myers-Squibb, Daiichi, GlaxoSmithKline, Incyte, Ipsen, Eli Lilly, Merck Sharp & Dohme, Merck KGaA, Mirati, Novartis, Nordic, Pierre Fabre, Pfizer, Roche, Seattle Genetics, Servier, Takeda, Terumo, Taiho, and Zymeworks; YYJ reports research funding to their institution from Merck Sharp & Dohme, the National Cancer Institute, the US Department of Defense, Cycle of Survival, Fred's Team, Rgenix, Bayer, Roche, Bristol-Myers Squibb, and Eli Lilly, fees for advisory board participation from Rgenix, Merck Serono, Bristol-Myers Squibb, Eli Lilly, Pfizer, Bayer, Imugene, Merck Sharp & Dohme, Daiichi Sankyo, Zymeworks, SeaGen, Basilea Pharmaceutical, Astra Zeneca, and equity in Rgenix; XF, C-SS, and PB are employees of and own stock options in Merck Sharp & Dohme; D-YO reports research funding to their institution from AstraZeneca, Novartis, Array, Eli Lilly, Servier, Beigene, Merck Sharp & Dohme, and Handok; and Y-JB reports research funding to their institution from Merck Sharp & Dohme and fees for consulting from Astellas, Amgen, Samyang Biopharm, Hanmi, and Daewoong.
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