Efficacy of lobaplatin plus S-1 and the predictive value of circulating tumor cell in patients with advanced gastric cancer

Abstract

Objective: To investigate the efficacy and safety of lobaplatin (LBP) plus S-1 for advanced gastric cancer (AGC) and determine the potential role of circulating tumor cells (CTC) for predicting the therapeutic response and prognosis. Methods: From January 2014 to February 2015, 64 consecutive patients with AGC received lobaplatin plus S-1 chemotherapy in Liaocheng People's Hospital. The clinical features, clinical response, adverse effects, prognosis and CTC pre- and post-treatment were retrospectively analyzed. The correlation between CTC and patients' disease control rate (DCR), objective response rate (ORR), progression free survival (PFS) as well as overall survival (OS) were investigated. Results: All 64 patients completed 2 cycles of chemotherapy.The number of patients who achieved complete regression, partial regression, stable and progression were 0, 24 (37.5%), 18 (28.1%) and 22 (34.4%), respectively. ORR was 37.5% and DCR was 65.6%. The median PFS was 10.8 months(95%CI 7.1-12.0) and the median OS was 16.1 months(95%CI 12.4-18.8). The ORR and PFS were not significantly different between patients with baseline CTC≥2 and CTC<2 (25.0% vs 53.6%, P=0.150; 6.2 months vs 7.5 months, P=0.780), while the DCR and OS were significantly different (45.9% vs 90.0%, P=0.008; 10.5 months vs 17.2 months, P<0.001). After 2 cycles of chemotherapy, the ORR and DCR in patients with CTC≥2 were 16.7% and 45.9%, respectively, which were significantly lower than those observed in patients with CTC<2 (50.0% and 90.0%, respectively). The former also had shorter median PFS and OS (6.6 months vs 8.9 months, 8.4 months vs 15.0 months, respectively). Patients with persistently CTC<2 or those exhibiting an conversion to CTC<2 following chemotherapy had an improved PFS and OS, while patients with persistently CTC≥2 or those exhibiting an conversion to CTC≥2 following therapy had shorter PFS and OS.The most frequent adverse effects were grade 1 or 2 gastrointestinal discomfort and myelosuppression. No patients discontinued chemotherapy because of adverse events. Conclusions: Lobaplatin plus S-1 had manageable safety profile and promising antitumor activity in patients with AGC. CTC could be used as a biomarker in evaluating therapeutic response and predicting their prognosis.