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WASHINGTON -- The FDA today granted accelerated approval to PD-L1 inhibitor atezolizumab (Tecentriq) for the most common form of bladder cancer.

The approval pertains to patients who have locally advanced or metastatic urothelial carcinoma that progressed during or after platinum-based chemotherapy, or within 12 months of receiving either neoadjuvant or adjuvant platinum-based chemotherapy. Urothelial carcinoma accounts for about 90% of all bladder cancer in the U.S.

Atezolizumab becomes the first PD-L1 inhibitor to receive FDA approval for any indication. The existing immune checkpoint inhibitors -- nivolumab (Opdivo) and pembrolizumab (Keytruda) -- target the PD-1 receptor, as opposed to the ligand (PD-L1).

"Products that block PD-1/PD-L1 interactions are part of an evolving story about the relationship between the body's immune system and its interaction with cancer cells," , director of the FDA Office of Hematology and Oncology Products, .

The accelerated approval, which comes with the stipulation of studies to confirm observed benefits with the drug, follows breakthrough therapy designation and priority review status previously granted by the FDA for atezolizumab. According to a statement from drug developer Genentech, atezolizumab should be available within 1 to 2 weeks.

The rapid approval was based primarily on results of the phase II open-label IMvigor 210 trial, which involved 310 patients and had a primary endpoint of objective response rate (ORR). The entire study population had an ORR of 14.8%, increasing to 26% in the subgroup of patients who had tumors with PD-L1 expression ≥5% in tumor-infiltrating lymphocytes. Among patients who had disease progression following neoadjuvant or adjuvant chemotherapy, the ORR was 22%.

Because of the suggestion that higher PD-L1 expression was associated with increased likelihood of response, the FDA also approved the Ventana SP142 assay for use in selecting patients for treatment with atezolizumab.

The most common grade 3/4 adverse events were urinary tract infection (9%); anemia (8%); fatigue (6%); dyspnea, acute kidney injury, abdominal pain, venous thromboembolism, sepsis, and pneumonia (4% each); and dehydration, intestinal obstruction, urinary obstruction, and hematuria (3% each).

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