A phase II study of modified docetaxel, cisplatin, and S-1 (mDCS) chemotherapy for unresectable advanced gastric cancer

Triplet therapy using docetaxel, cisplatin, and S-1 (DCS) against unresectable gastric cancer as previously reported by us showed high clinical efficacy, with a 87.1% total response rate; however, it also showed a high incidence of grade 3/4 toxicity. With the aim of reducing toxicities, we conducted a phase II study of modified DCS (mDCS), using a reduced dose of docetaxel, and evaluated the clinical efficacy and adverse events of this regimen. Patients with unresectable gastric cancer received chemotherapy with S-1 (40 mg/m(2) b.i.d) on days 1-14, and docetaxel (50 mg/m(2)) plus cisplatin (60 mg/m(2)) on day 8 every 3 weeks. The primary endpoint was the response rate (RR). Overall (OS) and progression-free survival (PFS), and toxicities were also evaluated. Forty-nine patients were enrolled from November 2011 to April 2014, and 43 were eligible. The overall RR was 79.1%, including two cases of a complete response (4.7%), and 32 cases of a partial response (74.4%). Nine cases had stable disease (20.9%) but none showed progressive disease. Of the 43 cases, 15 cases (34.9%) underwent curative conversion surgery. The median PFS was 350 days (95% CI 240-416 days) and median OS was 722 days (95% CI 411 days-not reached). Grade 3/4 neutropenia developed in 79.1%, and febrile neutropenia in 34.9%, of patients. Non-hematological grade 3/4 adverse events were anorexia (25.6%), nausea (4.7%), and diarrhea (9.3%). Modified DCS therapy showed high clinical efficacy sufficient enough to attempt conversion therapy against unresectable gastric cancer. Modified DCS showed fewer toxicities, but careful management of these is still essential.