Abstract 297P
Background
Immune checkpoint inhibitors (ICIs) are known to improve oncological outcomes in patients (pts) with mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI) solid tumours. ICI have obtained approval in 2022 as first-line treatment in combination with chemotherapy for advanced biliary tract cancer (BTCs) but MSI/dMMR BTCs are a rare subtype whose response to ICI is poorly describe. This multicentre study aims to describe clinical characteristics and the therapeutic strategy in current practice in pts with MSI/dMMR BTC.
Methods
We retrospectively included and collected data from all consecutive pts with MSI/dMMR BTC treated in 11 French centers. We reported outcomes (overall survival (OS) and progression free survival (PFS), according to RECIST V1.1) and tolerance particularly regarding ICI administration.
Results
Overall, 34 pts with MSI/dMMR BTC were included between 2015 and 2022. At diagnosis, 32% had a locally advanced stage and 29% were metastatic. More than 50% of pts had liver metastases.Twenty-eight (82%) patients received ICIs, including 5 in 1st line combined with chemotherapy, 2 in 1st line as monotherapy and 21 in subsequent line as monotherapy. Pts receiving ICI had a median OS from the initial diagnosis of 28.2 mts (CI95: 16.9-54.4) vs 15.6 mts (CI95: 5.8-18.1) for those who did not receive any ICI ; 60.7% of pts were still alive 2 years after ICI and 42.8% after 3 years. When ICI was used in 1st line, OS was 28.2 mts (CI95: 15.8 - 54.4) and PFS was 22.4 mts (CI95: 15.0 - 61.3). When ICI was used in ≥ 2 line, OS was 28.8 mts (CI95:17.8 - 48.3) and PFS was 5 mts (CI95: 0.0 - 10.7). OS from the start of ICI whatever the line was 14.2 mts (CI95: 6.8 - 29.1) and PFS was 10.8 mts (CI95: 5.8 - 20.5). Two pts had grade 3-4 irAE and 8 developed all grades irAE. Two pts were rechallenged with ICI after progression.
Conclusions
This is the first large real-world cohort which reports efficacy and tolerance of ICIs in pts MSI/dMMR BTC.
Legal entity responsible for the study
AGEO.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.