MSH2 and adjuvant cisplatin-based chemotherapy in non-small cell lung cancer

Abstract

CRA7502 Background: Adjuvant cisplatin-based chemotherapy improves survival among patients with non-small cell lung cancer. The human MutS homolog 2 (MSH2) protein is required to repair cisplatin-DNA lesions. Methods: We used immunohistochemistry to determine MSH2 expression in specimens from patients who had been enrolled in the International Adjuvant Lung Trial. The long-term (median follow-up 7.5 years) overall survival benefit was evaluated in a Cox model adjusted on clinical and pathological variables. Results: Among 673 evaluable tumors, 257 (38%) were MSH2 positive and 416 (62%) were MSH2 negative. The long-term survival benefit of chemotherapy was likely different according to MSH2 expression (test for interaction, P=0.06): chemotherapy compared with observation prolonged survival in the MSH2 negative group (adjusted hazard ratio for death, 0.76; 95%CI, 0.59 to 0.97; P=0.03), but not in the MSH2 positive group (adjusted hazard ratio for death, 1.12; 95%CI, 0.81 to 1.55; P=0.48). In the control arm, the adjusted hazard ratio for death associated with MSH2 positivity compared to MSH2 negativity was 0.66 (95%CI, 0.49 to 0.90; P=0.01). Among 658 patients with available excision repair cross-complementing group 1 (ERCC1) data, the benefit of chemotherapy decreased with the number of positive markers among MSH2 and ERCC1 (P=0.01). Chemotherapy compared with observation prolonged survival in the combined MSH2 negative/ERCC1 negative subgroup (adjusted hazard ratio for death, 0.65; 95%CI, 0.47 to 0.91; P=0.01). Conclusions: MSH2 appears to predict a long-term benefit from adjuvant cisplatin-based chemotherapy in patients with non-small cell lung cancer and may be combined with ERCC1. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration GlaxoSmithKline Eli Lilly