Apatinib in Combination with S-1 as First-Line Treatment in Patients with Advanced Metastatic Gastric Cancer: Results from an Open, Exploratory, Single-Arm, Phase II Trial.

LESSONS LEARNED Apatinib combined with S-1 was not superior to other chemotherapy regimens as first-line therapy for advanced gastric cancer. There was a tendency for patients with lymph node metastasis to have prolonged mPFS and mOS, compared with patients with liver metastasis. BACKGROUND The best choice of first-line chemotherapy regimen for patients with metastatic gastric cancer is still debated. We combined apatinib and S-1 as a new first-line therapy to treat advanced gastric cancer. The efficacy and safety of the combination were assessed, with the goal of determining the most appropriate subgroup of patients who could benefit from this new regimen. METHODS This study was an open, exploratory single-arm, phase II trial. Enrolled patients received apatinib plus S-1 treatment (apatinib, 500 mg, qd, d1-21 ; S-1, 40 mg/m2 , bid, d1-14 ). The primary endpoints were progression-free survival (PFS) and safety of this new regimen. Next-generation sequencing was used to explore potential biomarkers. RESULTS A total of 30 patients were enrolled. The mPFS was 4.21 months (95% CI, 2.29-6.13 months). The mOS was 7.49 months (95% CI, 4.81-10.17 months). Patients with lymph node metastasis had prolonged mPFS and mOS when compared with those with liver metastasis (mPFS: 4.21 vs 1.84 months; mOS: 8.21 vs 6.31 months, p=0.08). The most common grade 3 to 4 adverse events were abdominal pain, dizziness, and diarrhea. Gene mutation profiles between the two subgroups were significantly different. CONCLUSION Apatinib combined with S-1 was not superior to other chemotherapy regimens as first-line therapy for advanced gastric cancer. Toxicity was consistent with known profiles when given as monotherapy. There was a tendency toward prolonged mPFS and mOS in patients with lymph node metastasis compared with patients with liver metastasis, which could support the need to design a future clinical trial with a better defined patient population.