STAR-01: A randomized phase III clinical trial comparing PD-1 combined with apatinib and SOX，PD-1 combined with SOX, versus SOX alone in patients with advanced gastric adenocarcinoma.

e16070 Background: Gastric adenocarcinoma is one of the most common malignant tumors. With the recent research, it has been found that positive conversion therapy can benefit the survival of Advanced Gastric Cancer(AGC). Although more and more studies are exploring treatment options for AGC, the survival prognosis of advanced gastric cancer was still poor. Methods: The research attempted to compare the R0 resection rate, pathological complete response rate (pCR rate), disease response rate (ORR), overall survival (OS), 3-year disease free survival(DFS) and safety of three conversion therapies: PD-1 combined with apatinib and SOX(Group A), PD-1 combined with SOX(Group B), and SOX alone(Group C) in patients AGC. Our study enrolled 102 advanced patients, 96 of whom completed the study. Patients in all 3 groups received 4 cycles of conversion therapy and were evaluated for surgery based on the results of imaging evaluation. 4 cycles of conventional chemotherapy were performed after surgery. The study Registration Number was ChiCTR2000028845. Results: Of the 96 patients treated with the study approach, 11 had an radio-graphic Complete Remission(4 in Group A, 6 in B, and 1 in C). The Objective Response Rate(ORR) of the 4-drug(84.4%) and 3-drug(69.7%) combination groups were significantly better than that of the SOX alone group(45.2%). P(ABC) = 0.004, P(A-B) = 0.160, P(A-C) = 0.001, P(B-C) = 0.047. The results of Disease Control Rate was identical to ORR: Group A(87.5%) and Group B(87.9%) were significantly better than Group C(64.5%). P(ABC) = 0.029, P(A-B) = 1.000, P(A-C) = 0.032, P(B-C) = 0.027.After 4cycles of conversion therapy, 69 patients(24 in A, 25 in B, and 20 in C) underwent surgical treatment and 48 patients of them achieved R0 resection(18 in A, 16 in B, and 14 in C).It was disappointing that R0 resection rates were not statistically different among the three groups,P(ABC) = 0.704, P(A-B) = 0.404, P(A-C) = 0.711, P(B-C) = 0.671).There were 9 patients(2 in A, 6 in B, and 1 in C) got Pathologic Complete Response,P(ABC) = 0.124,P(A-B) = 0.273, P(A-C) = 1.000, P(B-C) = 0.182.The overall survival of the 3groups was respectively 24.63 , 26.36 and 16.06 months. Disease-free survival was 20.06 , 23.17 and 11.78 months. The survival of the 3-drug and 4-drug groups is significantly better than that of the SOX group, but the 4-drug group has no survival advantage than the 3-drug group.The adverse events between the 3 groups were not statistically significant, so the safety of the 3-drug combination and the 4-drug combination was assured. Conclusions: In conversion therapy for advanced gastric cancer, the combination of PD-1+SOX could improve ORR, pCR, R0 resection rate and survival expectation of patients compared with SOX alone. However, whether apatinib is introduced or not can not improve the ORR rate and survival of patients. Clinical trial information: ChiCTR2000028845 .