1. MBD4 deficiency is predictive of response to immune checkpoint inhibitors in metastatic uveal melanoma patients: A retrospective study
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Mathilde Saint-Ghislain, Lionnel Geoffrois, Lauris Gastaud, Thierry Lesimple, Sylvie Negrier, Nicolas Penel, Jean Emmanuel Kurtz, Yannick Le Corre, Caroline Dutriaux, Sophie Gardrat, Raymond Barnhill, Alexandre Matet, Nathalie Cassoux, Toulsie Ramtohul, Vincent Servois, Pascale Mariani, Sophie Piperno-Neumann, and Manuel Rodrigues
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Cancer Research ,Oncology - Abstract
e21601 Background: MBD4 encodes a glycosylase implicated in repair of lesions induced by DNA deamination and its inactivation in tumors is associated with a hypermutated phenotype. Uveal melanoma (UM) is a rare but aggressive form of melanoma carrying an extremely low mutation burden. Although metastatic UM (mUM) are usually resistant to immune checkpoint inhibitors (ICI), the first reported MBD4-mutated (MBD4m) patient responded to ICI, suggesting that MBD4 mutation may predict response to ICI. Since then, other MBD4-inactivated UMs, acute myeloid leukemias, colorectal adenocarcinomas, gliomas and spiradenocarcinoma cases have been reported. Methods: Retrospective cohort of mUM patients treated with ICI. MBD4 was sequenced in a subset of these patients. Results: Three hundred mUM patients were analyzed. Median follow-up was 17.3 months. Ten objective responses and 20 stable disease for > 12 months were observed, corresponding to an objective response rate of 3.3% and a clinical benefit (CB; i.e. responder patients and stable disease) rate of 10%. Median progression-free survivals (PFS) in patients without and with CB were 3.1 and 16.3 months, respectively (p < 0.0001). Of the 134 tumors sequenced for MBD4, five (3.7%) were mutated. MBD4 inactivation was associated with higher mutation burden (179 to 643 variants versus a median of 16 in MBD4 wild-type), better objective response rate as 60% of MBD4m versus 4% of MBD4-wild type patients responded (Fisher’s exact p-test = 0.0009). Median PFS was 4.0 months in MBD4-wild type and 22.3 months in MBD4m patients (HR = 0.22; p = 0.01). Median overall survival was 16.6 months in MBD4-wild type and unreached in MBD4m patients (HR = 0.11; p = 0.004). Conclusions: In mUM patients, MBD4 mutation is highly predictive for response to ICI, PFS and overall survival benefit. MBD4 could be a tissue-agnostic biomarker and should be sequenced in mUM and other tumor types where MBD4 mutations are reported.
- Published
- 2022
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