Survival benefit of adjuvant chemotherapy based on molecular residual disease detection in resected colorectal liver metastases: subgroup analysis from CIRCULATE-Japan GALAXY.

BACKGROUND: The prognostic role of circulating tumor DNA (ctDNA)-based molecular residual disease (MRD) detection and its utility for postsurgical risk stratification has been reported in colorectal cancer. In this study, we explored the use of ctDNA-based MRD detection in patients with colorectal liver metastases (CLM), for whom the survival benefit of adjuvant chemotherapy (ACT) after surgical resection remains unclear. METHODS: Patients with CLM without extrahepatic disease from the GALAXY study (UMIN000039205) were included. The disease-free survival (DFS) benefit of ACT was evaluated in MRD-positive and -negative groups after adjusting for age, gender, number, and size of liver metastases, RAS status, and previous history of oxaliplatin for primary cancer. ctDNA was detected using a personalized, tumor-informed 16-plex polymerase chain reaction-next-generation sequencing (mPCR-NGS) assay. ctDNA-based MRD status was evaluated 2-10 weeks after curative surgery, before the start of ACT. RESULTS: Among 6061 patients registered in GALAXY, 190 surgically resected CLM patients without any preoperative chemotherapy were included with a median follow-up of 24 months (1-48 months). ctDNA positivity in the MRD window was 32.1% (61/190). ACT was administered to 25.1% (48/190) of patients. In the MRD-positive group, 24-month DFS was higher for patients treated with ACT [33.3% versus not reached, adjusted hazard ratio (HR): 0.07, P < 0.0001]; whereas no benefit of ACT was seen in the MRD-negative group (24-month DFS: 72.3% versus 62.2%, adjusted HR: 0.68, P = 0.371). Multivariate analysis showed that the size of liver metastases (HR: 3.94, P = 0.031) was prognostic of DFS in the MRD-positive group. In the MRD-negative group, however, none of the clinicopathological factors were prognostic of DFS. CONCLUSIONS: Our data suggest that ACT may offer notable clinical benefits in MRD-positive patients with CLM. MRD status-based risk stratification could be potentially incorporated in future clinical trials for CLM.

Comprehensive clinical and molecular characterization of claudin 18.2 expression in advanced gastric or gastroesophageal junction cancer.

BACKGROUND: We conducted comprehensive clinical and molecular characterization of claudin 18.2 expression (CLDN18.2) in advanced gastric or gastroesophageal junction cancer (GC/GEJC). PATIENTS AND METHODS: Patients with advanced GC/GEJC who received systemic chemotherapy from October 2015 to December 2019 with available tumor specimens were analyzed. We evaluated clinicopathological features of CLDN18.2 expression with four molecular subtypes: mismatch repair deficient, Epstein-Barr virus-positive, human epidermal growth factor receptor 2-positive, and others. In addition, programmed death-ligand 1 (PD-L1) combined positive score (CPS), genomic alterations, and the expression of immune cell markers were assessed. Clinical outcomes of standard first- or second-line chemotherapy and subsequent anti-programmed cell death protein 1 (anti-PD-1) therapy were also investigated according to CLDN18.2 expression. RESULTS: Among 408 patients, CLDN18.2-positive (moderate-to-strong expression in ≥75%) was identified in 98 patients (24.0%) with almost equal distribution in the four molecular subtypes or CPS subgroups. CLDN18.2-positive was associated with Borrmann type 4, KRAS amplification, low CD16, and high CD68 expression. Overall survival with first-line chemotherapy was not significantly different between CLDN18.2-positive and -negative groups [median 18.4 versus 20.1 months; hazard ratio 1.26 (95% confidence interval 0.89-1.78); P = 0.191] regardless of stratification by PD-L1 CPS ≥5. Progression-free survival and objective response rates of first- and second-line chemotherapy, and anti-PD-1 therapy also showed no significant differences according to CLDN18.2 status. CONCLUSIONS: CLDN18.2 expression in advanced GC/GEJC was associated with some clinical and molecular features but had no impact on treatment outcomes with chemotherapy or checkpoint inhibition. CLDN18.2-positive also had no impact on overall survival. This information could be useful to interpret the results from currently ongoing clinical trials of CLDN18.2-targeted therapies for advanced GC/GEJC and to consider a treatment strategy for CLDN18.2-positive GC/GEJC.