Tislelizumab plus chemotherapy vs placebo plus chemotherapy as first-line treatment of advanced gastric or gastroesophageal junction adenocarcinoma: patient-reported outcomes in the Asian subgroup of the RATIONALE-305 study

OBJECTIVE: This study examined the patient-reported outcomes (PROs) in the Asian subgroup of patients from the RATIONALE-305 (NCT03777657) trial. METHODS: Adults with previously untreated, unresectable, or metastatic GC/GEJC were randomized (1:1) to receive either tislelizumab 200 mg or placebo IV once every 3 weeks, in combination with investigator-choice chemotherapy. PROs were evaluated using the EORTC QLQ-C30 and QLQ-STO22 questionnaires. Least-squares mean score changes from baseline to key clinical Cycles 4 and 6 were assessed using a mixed model for repeated measures. Time-to-deterioration (TTD) was also examined. RESULTS: This analysis included 748 Asian patients (376 in the tislelizumab arm; 372 in the placebo arm). At Cycle 4, both arms experienced clinically meaningful improvements in pain, with tislelizumab demonstrating significantly greater improvement than placebo. At Cycle 6, only the tislelizumab arm continued to show clinically meaningful improvement in pain. The mean treatment difference was significant for GHS/QoL, with the tislelizumab arm showing significantly greater improvement compared to the placebo arm. TTD analysis further showed that patients receiving tislelizumab had a lower risk of deterioration in QLQ-C30 physical functioning, QLQ-STO22 index score, and upper gastrointestinal symptoms. CONCLUSION: Asian patients receiving tislelizumab with chemotherapy reported better PRO outcomes compared to those receiving placebo with chemotherapy, particularly in GHS/QoL and pain/discomfort. Patients in the tislelizumab arm also experienced a lower risk of deterioration in overall gastric cancer symptoms, upper gastrointestinal symptoms, and physical functioning. These results, consistent with findings from the overall intention-to-treat population, support tislelizumab with chemotherapy as a first-line treatment for GC/GEJC.