Background: Patients with advanced/recurrent endometrial cancer have a poor prognosis and limited treatment options. Biomarkers such as tumor protein 53 ( TP53 ) in endometrial cancer can integrate novel strategies for improved and individualized treatment that could impact patient outcomes. In an exploratory analysis of the phase III ENGOT-EN5/GOG-3055/SIENDO study of selinexor maintenance monotherapy 80 mg in advanced/recurrent endometrial cancer, a pre-specified subgroup of patients with TP53 wild type (wt) endometrial cancer showed preliminary activity at long-term follow-up with a generally manageable safety profile (median progression-free survival 27.4 months vs 5.2 months placebo, HR=0.41)., Primary Objective: To evaluate the efficacy of selinexor compared with placebo as maintenance therapy in patients with advanced or recurrent TP53 wt endometrial cancer., Study Hypothesis: Selinexor administered at 60 mg weekly as maintenance therapy will show manageable safety and maintain efficacy in patients with TP53 wt advanced/recurrent endometrial cancer after systemic therapy versus placebo., Trial Design: This is a prospective, multicenter, double-blind, placebo-controlled, randomized phase III study designed to evaluate the efficacy and safety of selinexor as a maintenance therapy in patients with advanced or recurrent TP53 wt endometrial cancer., Major Inclusion/exclusion Criteria: Eligible patients must have histologically confirmed endometrial cancer, TP53 wt confirmed by next-generation sequencing, completed at least 12 weeks of platinum-based therapy with or without immunotherapy, with confirmed partial response or complete response, and primary Stage IV disease or at first relapse., Primary Endpoint: The primary endpoint is investigator-assessed progression-free survival per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 in the intent-to-treat population., Sample Size: A total of 220 patients will be enrolled., Estimated Dates for Completing Accrual and Presenting Results: Accrual is expected to be completed in 2024 with presentation of results in 2025., Trial Registration: NCT05611931., Competing Interests: Competing interests: IV reports consulting for Agenus, Akesobio, AstraZeneca, Bristol Myers Squibb, Deciphera Pharmaceuticals, Eisai, Elevar Therapeutics, F. Hoffmann-La Roche, Genmab, GSK, Immunogen, Jazzpharma, Karyopharm, Mersana, MSD, Novocure, Novartis, Oncoinvent, OncXerna, Sanofi, Regeneron, Seagen, Sotio, Verastem Oncology, Zentalis. APF has received grants/research support from AstraZeneca, Pharmamar, GSK (paid to the institution); participation in a company-sponsored speaker’s bureau for AstraZeneca, MSD, Eisai, GSK, Clovis, Pharmamar, Pharma&; and honoraria or consultation fees from GSK, Clovis, AstraZeneca, Pharmamar, Roche, MSD, Ability Pharma. BJM has received honorarium and consulting fees from Acrivon, Adaptimmune, Agenus, Akeso Bio, Amgen, Bayer, Elevar, EMD Merck, Genmab/Seagen, GOG Foundation, Gradalis, Heng Rui, ImmunoGen, Karyopharm, Iovance, Laekna Health Care, Mersana, Myriad, Novartis, Novocure, OncoC4, Panavance, Pieris, Pfizer, Puma, Regeneron, Sorrento, US Oncology Research, VBL, Verastem, Zentalis; and speaker/consultant fees from AstraZeneca, Clovis, Easai, Merck, Roche/Genentech, TESARO/GSK. TH reports scientific advisory board participation: Aadi, AZ, Caris, Clovis, Corcept, Epsilogen, Eisai, Genentech, GSK, J&J, Merck, Seagen. GV reports grants or contracts from advisory boards of AZ, MSD, Clovis, GSK Pharmamar, Eisai. Consulting fees, honoraria, and support for attending meetings from advisory boards of AZ, MSD, Clovis, GSK, Pharmamar, Eisai. DC has nothing to disclose. NC reports fees for advisory board membership for AstraZeneca, Clovis Oncology, Eisai, GSK, Immunogen, Mersana, MSD/Merck, Nuvation Bio, Oncxerna, Pieris, Roche, Novocure; fees as an invited speaker for AstraZeneca, Clovis Oncology, GSK, MSD/Merck, Eisai; institutional research grants from AstraZeneca, Roche, GSK; non-remunerated activities as member of the ESMO Guidelines Steering Committee and chair of the Scientific Committee of ACTO (Alleanza contro il tumore Ovarico). BP reports grants, advisory board, and consultant fees; institutional PI for industry sponsored trials from Tesaro/GSK, AstraZeneca, Merck, Genetech/Roche, Celsion, Karyopharm, Mersana, Takeda Pharmaceuticals, Toray, Imab, Sutro, SeaGen, Clovis Oncology. Compensated advisory boards include Tesaro/GSK, AstraZeneca, Lily, Mersana, Onconova, Merck, Clovis Oncology, Eisai, Toray, Sutro, Deciphera, Imab, SeaGen, GOG Foundation. JS reports research funding: Institution: AZ, Clovis Oncology, Merck, Bayer, PharmaMar, Pfizer, Tesaro, MSD Oncology, Roche. Consulting/advisory boards: AZ, Clovis Oncology, PharmaMar, Merck, Pfizer, Tesaro, MSD Oncology, Lilly, Novocure, J&J, Roche, Ingress Health, Riemser, Sobi, GSK, Novartis; honoraria: AZ, Eisai, Clovis Oncology, Olympus Medical Systems, J&J, PharmaMar, Pfizer, Teva, Tesaro, MSD Oncology, GSK, Bayer. Travel, accommodation, expenses: AZ, Clovis Oncology, PharmaMar, Roche Pharma AG, Tesaro, MSD Oncology, Olympus. JK has nothing to disclose. JB reports participation on advisory boards for AstraZeneca, Clovis, Mersana, OncoC4, Immingen. Speaker's bureau for AstraZeneca, Merck. CP reports honoraria from Novartis, Astra Zeneca, Genesis, MSD Oncology, Servier, WinMedica; has received fees for consulting or advisory role from Amgen, Astellas, BioPharma, Roche Hellas, Astra Zeneca; and research funding from Roche Hellas, WinMedica, Servier. TvG has received grants/research supports (all paid to institution) from Amgen, AstraZeneca, Roche; advisory board (all paid to institution): AstraZeneca, BioNTech, Eisai, GSK, ImmunoGen, Incyte, Karyopharm, MSD, OncXerna, Seagen, Tubulis, Zentalis; participation in a company sponsored speaker’s bureau (all paid to institution): GSK, ImmunoGen, MSD. DR has received fees for advisory boards from Mersana, GlaxoSmithKline, AstraZeneca, ProfoundBio, Eisai, Immunogen. Grants/research supports paid to institution from GlaxoSmithKline, Lilly, Celsion, Mersana, Hookipa, Syros, AstraZeneca, Shattuck Labs, ProfoundBio, CanariaBio, Immunogen, Karyopharm. MMC has nothing to disclose. YA has received grants/research supports from AstraZeneca; honoraria or consultation fees from AstraZeneca; MSD, Eisai, GSK. Consulting or advisory role with AstraZeneca, Eisai, MSD, GSK, Pfizer. MRM has received grants/research supports from AstraZeneca (institution); Boehringer Ingelheim (institution); Pfizer (institution); Tesaro (institution); honoraria or consultation fees from honoraria: Advaxis, AstraZeneca, Cerulean Pharma, Clovis Oncology, Novocure, Pfizer, Roche, Tesaro; consulting or advisory role: AstraZeneca, BioCad, Cerulean Pharma, Clovis Oncology, Genmab, Karyopharm Therapeutics, Novocure, Pfizer, Tesaro; stock shareholder: Karyopharm Therapeutics, SeraCare; and leadership: Karyopharm Therapeutics. KL is an employee of Karyopharm Therapeutics. PK is an employee of Karyopharm Therapeutics. BS reports consulting or advisory roles for Genentech, Eisai, AstraZeneca, Karyopharm Therapeutics, Incyte, Clovis Oncology, Myriad Genetic Laboratories Inc., GlaxoSmithKline LLC, AbbVie Inc., Seagen Inc., Novocure Inc., Novartis, Immunogen, Agenus, Merck Sharp & Dohme, GOG Foundation. RLC has received grant/research support from AstraZeneca/MedImmune (institution), Clovis Oncology (institution), Merck (institution), Roche/Genentech (an immediate family member), Immunogen (institution), Mirati Therapeutics (institution), Amgen (institution), Pfizer (institution), Lilly (institution), Regeneron (institution); honoraria or consulting fees from Clovis Oncology, Genentech/Roche, AstraZeneca/MedImmune, Genmab, OncoMed, Immunogen, AbbVie, Agenus, Novocure, Merck, OncXerna Therapeutics, Alkermes, Gradalis, GlaxoSmithKline, Eisai, GOG Foundation, Karyopharm Therapeutics; stock shareholder from McKesson; and is employed by US Oncology. Leadership: Onxeo. Travel, accommodation, expenses: Merck, AstraZeneca/MedImmune, Array BioPharma, Clovis Oncology, Roche/Genentech, Research to Practice, GOG Foundation, Clovis Oncology, Sotio, Vaniam Group., (© IGCS and ESGO 2024. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.)