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Updated: Dec 17, 2025
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Published on: May 2, 2025
A phase I study of toripalimab, an anti-PD-1 antibody, in patients with refractory malignant solid tumors
Xiao-Li Wei1, Chao Ren1, Feng-Hua Wang1
1Department of Medical Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P. R. China.
Background:
Several programmed cell death ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) antibodies have been approved for cancer treatment worldwide. Their pharmacokinetic and pharmacodynamic characteristics have been reported mainly in western countries, but related data in Chinese patients are limited. This study was conducted to investigate the safety, efficacy, pharmacokinetics, and pharmacodynamics of an anti-PD-1 antibody, toripalimab, in Chinese patients.
Methods:
A single-center phase I study was conducted in Sun Yat-sen University Cancer Center. Eligible patients were adults with histologically confirmed, treatment-refractory, advanced, solitary malignant tumors. Toripalimab was intravenously infused every 2 weeks in dose-escalating cohorts at 0.3 mg/kg, 1 mg/kg, 3 mg/kg, 10 mg/kg, and 240 mg. The study followed standard 3 + 3 design.
Results:
Between 15th March 2016 and 27th September 2016, 25 patients were enrolled, of whom 3 (12.0%), 7 (28.0%), 6 (24.0%), 6 (24.0%), 3 (12.0%) received 0.3 mg/kg, 1 mg/kg, 3 mg/kg, 10 mg/kg, and 240 mg toripalimab, respectively. After a median follow-up time of 5.0 months (range: 1.5-19.8 months), we observed that the commonest treatment-related adverse events (TRAEs) were fatigue (64.0%) and rash (24.0%). No grade 3 or higher TRAEs were observed. No dose-limiting toxicity, treatment-related serious adverse events (SAEs), or treatment-related death occurred. Objective response rate was 12.5%. The half-life of toripalimab was 150-222 h after a single dose infusion. Most patients, including those from the 0.3 mg/kg group, maintained complete PD-1 receptor occupancy (> 80%) on activated T cells since receiving the first dose of toripalimab.
Conclusions:
Toripalimab is a promising anti-PD-1 antibody, which was well tolerated and demonstrated anti-tumor activity in treatment-refractory advanced solitary malignant tumors. Further exploration in various tumors and combination therapies is warranted.
Insights
Toripalimab, an anti-programmed cell death protein 1 (PD-1) antibody, showed good tolerability and anti-tumor effects in Chinese patients with advanced cancers. Further studies are recommended for this promising cancer immunotherapy.
Area of Science:
- Immunotherapy
- Oncology
- Pharmacology
Background:
- Approved PD-L1/PD-1 antibodies exist for cancer treatment globally.
- Limited pharmacokinetic and pharmacodynamic data available for Chinese populations.
- Need for data on anti-PD-1 antibody toripalimab in Chinese patients.
Purpose of the Study:
- Investigate safety and efficacy of toripalimab in Chinese patients.
- Evaluate pharmacokinetics and pharmacodynamics of toripalimab.
- Assess toripalimab in treatment-refractory advanced solitary malignant tumors.
Main Methods:
- Phase I, single-center study with dose escalation (0.3-240 mg).
- Intravenous infusion of toripalimab every 2 weeks.
- Standard 3+3 design in adult patients with advanced, refractory tumors.
Main Results:
- 25 patients enrolled across dose cohorts.
- Common treatment-related adverse events: fatigue (64.0%) and rash (24.0%).
- No Grade 3+ TRAEs, SAEs, or deaths; Objective Response Rate: 12.5%; half-life: 150-222 h; sustained PD-1 occupancy (>80%).
Conclusions:
- Toripalimab is well-tolerated and shows anti-tumor activity.
- Promising candidate for treatment-refractory advanced cancers.
- Warrants further investigation in diverse tumors and combination therapies.
