Abstract 399P
Background
Endometrial cancers have the highest prevalence of MSI-H/MMR deficient variants. Our study evaluates the efficacy and safety of immunotherapy in metastatic dMMR endometrial cancer.
Methods
Our study aims to analyze the response rate and survival outcome in patients with metastatic endometrial cancer receiving immunotherapy at a tertiary-center. This is a retrospective analysis of patients with metastatic dMMR endometrial cancer who received immunotherapy from Jan 2020-Jan 2024. Testing of MMR was done by IHC on tumor tissue.
Results
58 patients were identified, 44(75%) were MMR-proficient and 14(24%) MMR-deficient. Among the 14, 11 received treatment with immunotherapy. 9 were endometroid variant, 1-high grade endometrial sarcoma and 1 had poorly differentiated carcinoma. MLH1 and PMS2 loss seen in 6 patients and 5 had MSH2 and MSH6 loss. Immunotherapy agents used were pembrolizumab and nivolumab. 10 received chemotherapy+immunotherapy (8 as first line and 2 as second line), one received immunotherapy as single agent first line treatment. Objective response-rate was 81%. 4(36%) had complete response, 5(45%) partial response and 2(18%) had disease progression. At a median follow-up of 20 months, median progression free survival (mPFS) was 31 months and median overall survival (mOS) was not reached. PFS rates at 12 and 24months were 64% and 50% respectively. 24months OS rate was 78%. Adverse events mainly were hypothyroidism, fatigue and skin rash with no grade 3/4 adverse events.
Conclusions
Our patients with dMMR endometrial cancers showed remarkable efficacy and long-term outcomes. It is mandatory to check for MMR in endometrial cancer patients to identify these subgroups who do very well.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.