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Dostarlimab+chemotherapy for the treatment of primary advanced or recurrent endometrial cancer: The placebo-controlled randomised phase III RUBY trial

ESMO Virtual Plenary

Session date: 27-28 March 2023

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VP2-2023: Dostarlimab+chemotherapy for the treatment of primary advanced or recurrent (A/R) endometrial cancer (EC): A placebo (PBO)-controlled randomised phase III trial (ENGOT-EN6-NSGO/GOG-3031/RUBY)

Published: March 27, 2023
DOI: https://doi.org/10.1016/j.annonc.2023.02.008
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M.R. Mirza, D. Chase, B.M. Slomovitz, ... R.L. Coleman, M.A. Powell
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Carboplatin-paclitaxel (CP) is standard of care (SOC) for first-line treatment of primary A/R EC; median OS is <3 yrs. Use of anti–PD-1s with chemo has improved outcomes in multiple tumour types. RUBY (NCT03981796) evaluated the efficacy and safety of the anti–PD-1 dostarlimab (D)+CP in A/R EC compared with CP alone.


RUBY is a phase III, global, randomised, double-blind, multicentre, PBO-controlled study. Pts with primary advanced stage III or IV or first recurrent EC were randomised 1:1 to receive dostarlimab 500 mg, or PBO, plus carboplatin AUC 5 and paclitaxel 175 mg/m2 Q3W (6 cycles), followed by dostarlimab 1000 mg, or PBO, monotherapy Q6W for up to 3 yrs. Primary endpoints were PFS by investigator assessment per RECIST v1.1 and OS. Graphical method was used for hypothesis testing of PFS in the dMMR/MSI-H population, then the overall population, and OS in the overall population. A prespecified exploratory analysis of PFS in MMR proficient (MMRp)/MS stable (MSS) pts was also performed. Safety was assessed.


Of 494 pts randomised (245 D+CP; 249 PBO+CP), 23.9% had dMMR/MSI-H tumours (53 D+CP; 65 PBO+CP), 47.8% had recurrent disease; 18.6% and 33.6% had primary stage III and IV disease, respectively. PFS and OS results are presented in the table. Discontinuation of dostarlimab or PBO due to a TEAE occurred in 17.4% pts receiving D+CP and 9.3% pts receiving PBO+CP. The safety profile of D+CP was generally consistent with the safety profile of each drug.


D+CP showed statistically significant and clinically meaningful PFS benefits in the dMMR/MSI-H and overall populations vs CP alone. A clinically relevant benefit in PFS was also observed in the MMRp/MSS population. An early trend toward improved OS was observed in all populations. The combination of dostarlimab+CP represents a new SOC for pts with newly diagnosed primary A/R EC.

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Simultaneous publication in the New England Journal of Medicine

Mansoor R. Mirza, Dana M. Chase, Brian M. Slomovitz, et al. Dostarlimab for Primary Advanced or Recurrent Endometrial CancerN Engl J Med 2023; 23 March 2023. doi: 10.1056/NEJMoa2302312

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