Phase I study of the antiprogrammed cell death‐1 Ab spartalizumab (PDR001) in Japanese patients with advanced malignancies

Spartalizumab is a humanized IgG4/κ mAb directed against human programmed cell death‐1 (PD‐1). In this phase I study, we investigated safety, pharmacokinetics, preliminary antitumor activity, and toxicity of spartalizumab in patients with advanced malignancies. Patients (n = 18) with a range of tumor types received spartalizumab i.v. at doses of 1, 3, and 10 mg/kg every 2 weeks until disease progression, unacceptable toxicity, or discontinuation at the discretion of the investigator or patient. Most patients (61%) had received five or more prior lines of therapy. No dose‐limiting toxicities were reported and, hence, the maximum tolerated dose was 10 mg/kg or more. Pharmacokinetics in Japanese patients aligned with those reported in a global dose‐escalation study. The safety profile was consistent with other approved anti‐PD‐1 mAbs; the most common drug‐related adverse events were maculopapular rash (22%), followed by malaise and increased blood alkaline phosphatase (11% each). Partial responses were reported in two patients (11%), one with transitional cell carcinoma and the other with hepatocellular carcinoma. In conclusion, this study confirmed the safety of spartalizumab given at a dose of up to 10 mg/kg every 2 weeks in Japanese patients with cancers.