On May 18, 2016, the FDA granted accelerated approval to atezolizumab (Tecentriq; Genentech) for the treatment of patients with locally advanced or metastatic urothelial carcinoma who have disease progression during or after platinum-containing chemotherapy, or for those who have had disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.
Atezolizumab received a breakthrough therapy designation in May 2014 for the treatment of metastatic bladder cancer that expresses PD ligand 1 (PD-L1) and was granted a priority review by the FDA for the treatment of locally advanced or metastatic urothelial carcinoma.
The accelerated approval of atezolizumab was based on the results of the IMvigor 210 study, an open-label, multicenter, single-arm, phase 2 clinical trial of 310 patients with locally advanced or metastatic urothelial carcinoma who received 1200 mg of atezolizumab intravenously. The study’s primary end point was objective response rate, and the secondary end point was the duration of response.
Atezolizumab conferred at least partial shrinkage of tumor in 9.4% of patients. The objective response rate in the study was 14.8%, and the median duration of response ranged from 2.1 months to 13.8 months. The objective response rate was 9.5% in patients with PD-L1 expression of <5% and 26% in patients with PD-L1 expression ≥5%, suggesting that the level of PD-L1 expression may help to identify the patients who are more likely to respond to therapy with atezolizumab.
On the same day, the FDA approved the Ventana PD-L1 assay, which is designed to detect PD-L1 levels in the tumor and help clinicians identify patients who would most benefit from treatment with atezolizumab.
The most common (≥20%) adverse events (all grades) associated with atezolizumab included fatigue (52%), decreased appetite (26%), nausea (25%), urinary tract infection (22%), pyrexia (21%), and constipation (21%). The most common (≥2%) grade 3 or 4 adverse events included urinary tract infection (9%), fatigue (6%), abdominal pain (4%), and dyspnea (4%).
Atezolizumab is being evaluated in the confirmatory phase 3 IMvigor 211 study, and is expected to become available for use in June.