Article Text
Abstract
Introduction/Background The efficacy and safety evidence of dostarlimab monotherapy in patients with MisMatch Repair deficient/MicroSatellite Instability-High (dMMR/MSI-H) endometrial cancer (EC) who progressed during or after a platinum-containing regimen, comes from the analysis of 143 patients who were enrolled in a phase I clinical trial (GARNET). Therefore, assessing dostarlimab in a real-world scenario is highly relevant.
Methodology GEICO 120/DORA is a multicentre, retrospective, observational study, in dMMR/MSI-H recurrent or advanced patients with EC treated in a real-world setting within the Spanish dostarlimab Expanded Access Program (EAP), conducted between January 2021 and February 2023. Included patients progressed to prior platinum-containing regimen and received at least 1 cycle of dostarlimab. The primary endpoint was overall response rate (ORR) per RECIST v1.1 and duration of response (DOR). Safety and tolerability of dostarlimab were key secondary endpoints.
Results Between March and September 2023, 129 patients were registered by 57 GEICO hospitals, 128 met inclusion criteria and 125 were evaluable for radiological response. Patients’ characteristics are described in Table 1. The median duration of dostarlimab administration was 8.8 months (IQR, 13.2) and 74 patients (57.4%) remained on therapy upon analysis. The median follow-up was 11.6 months. The best responses to dostarlimab were: 27 (21.1%) complete responses, 40 (31.3%) partial responses, 33 (25.8%) stabilizations, and 25 (19.5%) progressions, with a median time to response of 2.9 months (95% CI, 2.6–3.3). DOR at 6 and 12 months was 96.3 and 87.1%, while 66.4% and 42.2% patients were progression-free at 6 and 12 months, respectively. Only 4.7% of patients discontinued treatment due to toxicity. Asthenia (16.3%) and hypothyroidism (10.1%) were the most frequent dostarlimab-related adverse events.
Conclusion Dostarlimab monotherapy in dMMR/MSI-H EC in a real-world setting is associated to similar efficacy outcomes to those observed in GARNET trial. To our knowledge this is the largest series evaluating dostarlimab monotherapy after GARNET trial.
Disclosures Attached