1. Efficacy of anti-epidermal growth factor antibody rechallenge in RAS/BRAF wild-type metastatic colorectal cancer: a multi-institutional observational study.
- Author
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Fukuda, Koshiro, Osumi, Hiroki, Yoshinami, Yuri, Ooki, Akira, Takashima, Atsuo, Wakatsuki, Takeru, Hirano, Hidekazu, Nakayama, Izuma, Ouchi, Kota, Sawada, Ryoichi, Fukuoka, Shota, Ogura, Mariko, Takahari, Daisuke, Chin, Keisho, Shoji, Hirokazu, Okita, Natsuko, Kato, Ken, Ishizuka, Naoki, Boku, Narikazu, and Yamaguchi, Kensei
- Abstract
Purpose: To investigate circulating tumor DNA (ctDNA) RAS mutant (MT) incidence before salvage-line treatment and the clinicopathological features and molecular biological factors associated with the efficacy of anti-epithelial growth factor receptor (EGFR) monoclonal antibody (mAb) rechallenge for tissue RAS/BRAF wild type (WT) metastatic colorectal cancer (mCRC). Methods: This multi-institutional retrospective observational study included 74 patients with mCRC with tissue RAS/BRAF WT refractory to first-line chemotherapy containing anti-EGFR mAb. ctDNA RAS status was assessed using the OncoBEAM™ RAS CRC Kit. We explored the clinicopathological features associated with ctDNA RAS status and the factors related to anti-EGFR mAb rechallenge efficacy in multivariate Cox proportional hazard regression. Results: The incidence of RAS MT in ctDNA was 40.5% (30/74), which was associated with primary tumor resection (P = 0.016), liver metastasis (P < 0.001), and high tumor marker levels (P < 0.001). Among the 39 patients treated with anti-EGFR mAb rechallenge, those with ctDNA RAS WT showed significantly longer progression-free survival (PFS) than those with ctDNA RAS MT (median 4.1 vs. 2.7 months, hazard ratio [HR] = 0.39, P = 0.045). Patients who responded to first-line anti-EGFR mAb showed significantly longer PFS (HR = 0.21, P = 0.0026) and overall survival (OS) (HR = 0.23, P = 0.026) than those with stable disease. Conclusions: The incidence of ctDNA RAS MT mCRC was 40.5%, which was associated with liver metastases and high tumor volumes. Anti-EGFR mAb rechallenge may be effective for patients with mCRC who responded to first-line chemotherapy containing anti-EGFR mAb. No patients with RAS MT in ctDNA responded to anti-EGFR mAb rechallenge. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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