Serum CYFRA 21-1 as a biomarker of pemetrexed plus cisplatin treatment in nonsquamous non-small cell lung cancer.

Abstract

e18014 Background: Pemetrexed (P) is a key drug in the treatment of advanced non-squamous (N-Sq) non-small cell lung cancer (NSCLC). Although differential efficacies of P between squamous (Sq) and N-sq subtypes have been reported, it is difficult to get a clear histological diagnosis from a small biopsy sample. Therefore, a more objective, yet simple, biomarker for histology-based treatment is needed. Previously, we reported that serum Cytokeratin fragment 21-1 (CYFRA) was related to the outcome of P monotherapy. In this study, we examined whether serum CYFRA could predict the efficacy of the cisplatin-pemetrexed (CP) combination regimen as well as it did for P monotherapy. Methods: Pre-treatment serum concentrations of CYFRA, carcinoembryonic antigen (CEA), squamous cell carcinoma (SCC) antigen, and sialyl Lewis X-I antigen (SLX) were measured in 50 N-sq NSCLC patients who were enrolled in a phase II study of C (75 mg/m2 and 500 mg/m2) against N-Sq NSCLC. Eligibility criteria consisted of histologically or cytologically confirmed recurrent or metastatic N-Sq NSCLC previously untreated with chemotherapy, ECOG performance status (PS) 0-1. The primary endpoint was response rate, which was evaluated with RECIST. The planned sample size was 50 patients. We analyzed possible associations between these NSCLC marker levels and the efficacy of the CP regimen. Results: From April 2010 to June 2011, 50 N-sq NSCLC patients (male/female, 34/16; median age 60 y (28-74 y)) were enrolled in this study. Patients’ histological characteristics were: adeno/large/not otherwise specified (NOS), 39/5/6; PS: 0/1, 31/19. In these 50 patients, elevated levels of serum CYFRA, CEA, SCC and SLX were found in 25, 32, 5 and 32 patients, respectively. CYFRA was significantly associated with progression-free survival (PFS) (median PFS: 5.53 vs. 3.29 months; p < 0.05), whereas no significant associations were observed between PFS and CEA, SCC or SLX. In addition, multivariate analysis showed that higher CYFRA and PS levels were significant factors associated with a shorter PFS. (p < 0.05) Conclusions: Serum CYFRA is related to the outcome of CP treatment; our results suggest that serum CYFRA is a promising predictive marker of CP therapy.