Immune checkpoint inhibitors (ICIs) have substantially advanced the treatment of patients with malignant melanoma. However, improving therapeutic efficacy requires identifying drug combinations that elicit durable responses without inducing intolerable toxicity. Within that context, selinexor emerges as a possible combination option that has been shown in preclinical studies to enhance the efficacy of ICI therapy. Methods: In this phase 1b study, we investigated selinexor in combination with pembrolizumab in 25 patients with advanced non-uveal melanoma. Patients received selinexor at a dosage of 60 mg taken orally twice weekly, and pembrolizumab intravenously at a dosage of 200 mg every 3 weeks. Results: Despite the high incidence of adverse events (96%), most treatment-related toxicities were manageable with supportive care and dose reductions. The most common adverse events of any grade were nausea ( n = 20; 80%), decreased white blood cell count ( n = 15; 60%), vomiting ( n = 14; 56%), anemia ( n = 12; 48%), fatigue ( n = 12; 48%), and decreased platelet count ( n = 12; 48%). The 10 patients with treatment-naïve evaluable disease had an objective response rate (ORR) of 70% ( n = 7, including three patients with complete response), which was significantly higher than that of the 14 patients with prior anti-programmed cell death protein 1 (anti-PD-1) therapy, whose ORR was 7% ( n = 1; p = 0.002). Stable disease was observed in two patients (20%) with treatment-naïve disease and seven patients (50%) with prior anti-PD-1 therapy. Conclusion: Selinexor combined with pembrolizumab showed promising antitumor activity in patients with treatment-naïve metastatic melanoma. The toxicity profile of the combination was consistent with that reported for individual agents, with no additional safety concerns., Competing Interests: Conflicts of Interest: Justin Moyers reports being on the advisory board for Replimmune. Sarina Piha-Paul reports institutional clinical trial research support/grant funding from AbbVie, Inc., ABM Therapeutics, Inc., Acepodia, Inc, Alkermes, Aminex Therapeutics, BioMarin Pharmaceutical, Inc, Boehringer Ingelheim, Bristol Myers Squib (BMS), Cerulean Pharma, Inc., Chugai Pharmaceutical Co., Ltd, Curis, Inc., Cyclacel Pharmaceuticals, Daiichi Sankyo, Eli Lilly, ENB Therapeutics, Epigenetix Inc., Five Prime Therapeutics, F-Star Beta Limited, F-Star Therapeutics, Gene Quantum, Genmab A/S, Gilead Sciences, Inc., GlaxoSmithKline, Helix BioPharma Corp., Hengrui Pharmaceuticals, Co., Ltd., HiberCell, Inc., Immunomedics, Inc., Incyte Corp., Jacobio Pharmaceuticals Co., Ltd., Jiangsu Simcere Pharmaceutical Co., Ltd., Loxo Oncology, Inc., Lytix Biopharma AS, Medimmune, LLC., Medivation, Inc., Merck Sharp and Dohme Corp., Nectin Therapeutics, Ltd., Novartis Pharmaceuticals, Nurix, Pieris Pharmaceuticals, Inc., Pfizer, Phanes Therapeutics, Principia Biopharma, Inc., Puma Biotechnology, Inc., Purinomia Biotech, Inc., Rapt Therapeutics, Inc., Replimune, Roche/Blueprint, Seattle Genetics, Silverback Therapeutics, Shasqi, Inc., Synlogic Therapeutics, Taiho Oncology, Tesaro, Inc., Theradex Oncology, Toragen Therapeutics, Inc., TransThera Bio, Xencor, Inc, and ZielBio, Inc.; National Cancer Institute/National Institutes of Health (P30CA016672 – Core Grant, CCSG Shared Resources); and consulting for CRC Oncology. David S. Hong reports institutional research grant funding from AbbVie, Adaptimmune, Adlai-Nortye, Amgen, Astelles, Astra-Zeneca, Bayer, Biomea, BMS, Daiichi-Sankyo, Deciphera, Eisai, Eli Lilly, Endeavor, Erasca, F. Hoffmann-LaRoche, Fate Therapeutics, Genentech, Genmab, Immunogenesis, Incyte Inc, Infinity, Kyowa Kirin, Merck, Mirati, Navier, NCI-CTEP, Novartis, Numab, Pfizer, Pyramid Bio, Quanta, Revolution Medicine, SeaGen, STCube, Takeda, TCR2, Turning Point Therapeutics, and VM Oncology; travel-related support from AACR, ASCO, CLCC, Bayer, Genmab, Northwestern, SITC, Telperian, UNC; consulting, speaker, or advisory roles for 280Bio-YingLing Pharma, Abbvie, Acuta, Adaptimmune, Alkermes, Alpha Insights, Amgen, Affini-T, Astellas, Aumbiosciences, Axiom, Baxter, Bayer, BeiGene USA, Boxer Capital, BridgeBio, CARSgen, CLCC, COG, COR2ed, Cowen, Ecor1, EDDC, Erasca, Exelixis, Fate Therapeutics, F.Hoffmann-La Roche, Genentech, Gennao Bio, Gilead, GLG, Group H, Guidepoint, HCW Precision Oncology, Immunogenesis, Incyte Inc, Inhibrix Inc, InduPro, Innovent, Janssen, Jounce Therapeutics Inc, Lan-Bio, Liberium, MedaCorp, Medscape, Novartis, Northwestern, Numab, Oncologia Brasil, ORI Capital, Pfizer, Pharma Intelligence, POET Congress, Prime Oncology, Projects in Knowledge, Quanta, RAIN, Ridgeline, Revolution Medicine, Sanofi and Genzyme Inc, SeaGen, Stanford, STCube, Takeda, Tavistock, Trieza Therapeutics, T-Knife, Turning Point Therapeutics, UNC, WebMD, Ziopharm; and other ownership interests in CrossBridge Bio (Advisor), Molecular Match (Advisor), OncoResponse (Founder, Advisor), Telperian (Founder, Advisor). Funda Meric-Bernstam reports consulting for AbbVie, Aduro BioTech Inc., Alkermes, AstraZeneca, Daiichi Sankyo Co. Ltd., Calibr (a division of Scripps Research), DebioPharm, Ecor1 Capital, eFFECTOR Therapeutics, F. Hoffman-La Roche Ltd., GT Apeiron, Genentech Inc., Harbinger Health, IBM Watson, Incyte, Infinity Pharmaceuticals, Jackson Laboratory, Kolon Life Science, LegoChem Bio, Lengo Therapeutics, Menarini Group, OrigiMed, PACT Pharma, Parexel International, Pfizer Inc., Protai Bio Ltd, Samsung Bioepis, Seattle Genetics Inc., Tallac Therapeutics, Tyra Biosciences, Xencor, Zymeworks; advisory Committee membership for Black Diamond, Biovica, Eisai, FogPharma, Immunomedics, Inflection Biosciences, Karyopharm Therapeutics, Loxo Oncology, Mersana Therapeutics, OnCusp Therapeutics, Puma Biotechnology Inc., Seattle Genetics, Sanofi, Silverback Therapeutics, Spectrum Pharmaceuticals, Theratechnologies, and Zentalis; institutional research funding from Aileron Therapeutics, Inc., AstraZeneca, Bayer Healthcare Pharmaceutical, Calithera Biosciences Inc., Curis Inc., CytomX Therapeutics Inc., Daiichi Sankyo Co. Ltd., Debiopharm International, eFFECTOR Therapeutics, Genentech Inc., Guardant Health Inc., Klus Pharma, Takeda Pharmaceutical, Novartis, Puma Biotechnology Inc., Taiho Pharmaceutical Co.; honoraria from Dava Oncology; and travel-related support from European Organisation for Research and Treatment of Cancer (EORTC), European Society for Medical Oncology (ESMO), Cholangiocarcinoma Foundation, and Dava Oncology. Sapna P. Patel reports institutional clinical trial support from BMS, Foghorn Therapeutics, Ideaya, InxMed, LyvgenBiopharma, Novartis, Provectus Biopharmaceuticals, Seagen, SyntrixBio, and TriSalusLifeSciences; consulting, advisory board, steering committee, and/or data safety monitoring board for BMS, CardinalHealth, CastleBiosciences, Delcath, Ideaya, Immatics, Immunocore, IOBiotech, MSD, Novartis, OncoSec, Pfizer, Replimune, Scancell, and TriSalus Life Sciences; and honoraria from BMS, MSD, and Novartis. Isabella G. Oliva reports institutional research funding from Merck, BMS, and Pfizer; and advisory board for BMS, Novartis, and Pfizer; and consulting or speaker role for Pfizer, Novartis, Biodexa, and Everclear. The remaining authors have no conflicts of interest.