Abstract 7624: DNA checkpoint gene mutation as a biomarker of immune checkpoint inhibitor in advanced biliary tract cancer

• Published in: Cancer research (Chicago, Ill.) Vol. 84; no. 6_Supplement; p. 7624
• Main Authors: Shin, Ji Eun, Kim, Seung Tae, Choi, Dae-Ho, Lee, Junho, Hyeon, Jiyeon
• Format: Journal Article
• Language: English
• Published: 22-03-2024
• ISSN: 1538-7445; 1538-7445
• DOI: 10.1158/1538-7445.AM2024-7624

Introduction: The DNA checkpoint (DNACHK) pathway is engaged in signaling the need for cell cycle arrest. The G1 and S phase checkpoint allows for repair of damaged DNA, preventing damaged DNA from being copied. The G2 and M phase checkpoint prevents transmission of mutated DNA to the next generation. This pathway, along with mismatch repair (MMR), homologous recombination (HR), and base excision repair (BER), is being actively researched to assess its role in cancer immunotherapy.
Methods: Sixty-two patients participated in this study. These patients were treated with immune checkpoint inhibitors (ICIs) for advanced biliary tract cancers (BTCs) from Mar. 2020 to Aug. 2022 at Samsung Medical Center. DNACHK mutations were defined as genomic alterations such as SNVs, MNVs, and short insertion and deletions in seven genes These genes include checkpoint kinase 1 (CHEK1), checkpoint kinase 2 (CHEK2), BRCA1, DNA repair associated (BRCA1), the serine/threonine kinase ATM, the serine/threonine kinase ATR, and mediator of DNA damage checkpoint 1 (MDC1). We analyzed the effect of DNACHK mutations on the efficacy of ICIs in advanced BTCs.
Results: Patient median age at diagnosis was 68.0 years. Ten patients (16.1%) had gall bladder (GB) cancer; the remaining patients (n = 52, 83.9%) were diagnosed with cholangiocarcinoma. Among the 62 patients with advanced BTCs treated with ICIs, 37 (59.7%) were categorized into the DNACHK wild-type (WT) group and 25 (40.3%) into the DNACHK mutated (MT) group. The most observed DNA checkpoint mutations were ATM mutations (n=14). MDC1 mutations were found in seven patients, ATR mutations in three, BRCA1 mutations in four, and CHEK2 mutations in three. Patients in the DNACHK MT group had better disease control rates than patients in the DNACHK WT group (60.0% vs. 48.6%, p=0.53). Median overall survival (OS) was 8.1 months (95% CI, 5.1, 22.8) in the MT group and 5.6 months (95% CI, 3.1, 11.0) in the WT group (p=0.33).
Conclusions: The results of this study suggest that the DNACHK pathway may be a valuable source of biomarkers for ICI and worthy of further study.
Citation Format: Ji Eun Shin, Seung Tae Kim, Dae-Ho Choi, Junho Lee, Jiyeon Hyeon. DNA checkpoint gene mutation as a biomarker of immune checkpoint inhibitor in advanced biliary tract cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7624.