Toripalimab Combined With Nab-Paclitaxel/Docetaxel As Second-Line Treatment In Patients With Advanced Gastric Cancer: Preliminary Results From A Single-Arm, Open-Label Phase Ii Trial

Paclitaxel is the standard second-line treatments for advanced gastric cancer (GC). However, the patient's prognosis is poor. Toripalimab, a humanized IgG4 mAb against Programmed Death-1 (PD-1), has shown significant clinical efficacy in various cancers. Herein, we explored to evaluate the efficacy and safety of toripalimab combined with paclitaxel as second-line treatment in GC patients (pts). This was an ongoing single-armed, single-centred phase II trial. Pts with advanced gastric adenocarcinoma who had failed to prior first-line fluorouracil chemotherapy or the end of adjuvant chemotherapy with fluorouracil less than 6 months were recruited in this study. Eligible subjects were given nab-paclitaxel (125mg/m2, iv, d1 and d8, q3w) / Docetaxel (60-75mg/m2, iv, d1, q3w) plus toripalimab (240 mg, iv, d1, q3w) for 4-8 cycles or until disease progression or unacceptable toxicity. Tumor assessment was performed every 6 weeks by investigator according to RECIST version 1.1. The primary endpoint were objective response rate (ORR) and disease control rate (DCR). The secondary endpoints included progression free survival (PFS), safety and one-year overall survival rate. From Aug 24, 2020 to Apr 15, 2021, 15pts had been recruited. Male: 46.6%; median age: 53y; 7 pts received docetaxel and 8 pts received nab-paclitaxel, 7 pts were available for efficacy evaluation. In best overall response assessment, confirmed partial response (PR) was observed in 1/7 pts, stable disease (SD) was observed in 4/7 pts. ORR was 14.2% (95% CI: 2.6∼51.3), and DCR was 71.4% (95% CI: 35.9∼91.8). The median PFS of the 7 pts was not yet available. The most common treatment-related adverse events (TRAEs) were myelosuppression, gastrointestinal reaction, fatigue, constipation, rash and hepatotoxicity. TRAEs were mostly grade 1-2, the common grade 3-4 TRAEs were myelosuppression (26.7%). Toripalimab in combination with paclitaxel as second-line therapy for advanced GC showed tolerant toxicity and preliminary clinical efficacy. The conclusion should be validated in more pts consecutively.