A phase I study of JS001, a humanized IgG4 mAb against programmed death-1 (PD-1) in patients with advanced solid tumors.

Abstract

3067 Background: JS001 blocks the interaction between PD-1 and its ligands and eradicates established tumor in human PD-1 Knock-in mouse model. Methods: A Phase I open-label study is designed to evaluate the safety and tolerability of JS001 in advanced solid tumor pts who are refractory to standard therapy. The study has a 3+3 dose escalation design with planned cohorts at 1, 3, and 10 mg/kg followed by a dose expansion. (Clinical Trial ID: NCT02836795). Results: As of January 27, 2017, pts enrollment has been completed with 36 pts from 3 indications (22 Melanoma; 9 Urothelial Carcinoma; 5 Renal Cell Carcinoma). The majority of melanomas are acral and mucosal origin. No DLT was observed and no MTD was reached in the study. The most common treatment-related AEs were grade 1/2, including hyper- or hypo-thyroidism (42%), rash (39%), fever (28%), leukopenia (22%), elevation of liver enzymes (19%), anorexia (17%), and fatigue (14%). Treatment–related grade 3 AEs include proteinuria (n = 1), and lipase increase (n = 2). The emergence of AEs is not dose related. JS001 PK shows dose-dependent exposure with the elimination half-life of 6 to 12 days. Among 32 evaluable pts, 1 pt have complete response (melanoma), 6 pts have partial response (3 melanoma, 2 RCC and 1 UC), and 10 pts achieve stable disease, for an ORR of 22% and a DCR of 53%. 6 out of 7 CR/PR pts still have ongoing response. Two groups of pts benefited most from JS001 treatment, pts with high tumor-infiltrating lymphocytes (TIL) (50% ORR) and pts with > 1% PD-L1 expression in tumor biopsy (46% ORR). Conclusions: JS001 exhibited a favorable safety profile in human. Treatment related AEs are in line with those from approved drugs in the same class. JS001 has demonstrated promising anti-tumor activity, especially in previously under-evaluated acral (20% ORR, 53% DCR) and mucosal (25% ORR, 50% DCR) melanomas. Clinical trial information: NCT02836795.