An investigation of extended-interval dosing of atezolizumab in Japanese patients with advanced solid tumors: safety and pharmacokinetics of a dose of 1680 mg every 4 weeks.

In Japan, atezolizumab is indicated for several cancers at a dose of 1200 mg every 3 weeks or 840 mg every 2 weeks. This open-label study (jRCT2031220151) aimed to assess an atezolizumab monotherapy dose of 1680 mg every 4 weeks (Q4W) in Japanese patients ≥ 18 years of age with advanced or recurrent solid tumors that were not responsive to standard treatment. The primary endpoints were tolerability, safety, and pharmacokinetics (PK). Secondary endpoints included overall response rate and progression-free survival. Overall, 21 patients were enrolled in the study. The median age for males (42.9%) and females (57.1%) was 61 years, and the median (range) treatment duration was 29.0 (1-224) days. During the dose-limiting toxicity (DLT) evaluation period, 3 out of 6 (50.0%) patients experienced at least 1 adverse event, although no DLTs or deaths were experienced. The PK profile of atezolizumab 1680 mg Q4W monotherapy in cycle 1 after 30 min of administration had an arithmetic mean maximum concentration (standard deviation [SD]) of 699 (146) µl/mL and a mean minimum concentration (SD) 133 (46.0) µl/mL, The mean (SD) area under the curve was 7180 (1340) days‧µg/mL. These data show that atezolizumab 1680 mg Q4W monotherapy was well tolerated in Japanese patients with no new safety concerns, suggesting that this less frequent dosing regimen could have the potential to offer greater flexibility and convenience for patients and caregivers.