The FDA has given the green light to atezolizumab (Tecentriq, Genentech) for the treatment of patients with urothelial carcinoma, the most common type of bladder cancer. Atezolizumab is the first product in its class (programmed death-1/programmed death ligand-1 [PD-1/PD-L1] inhibitors) approved to treat this type of cancer.
Atezolizumab targets the PD-1/PD-L1 pathway (proteins found in immune cells and in some cancer cells). By blocking these interactions, atezolizumab may help the body’s immune system fight cancer cells. Atezolizumab is the first FDA-approved PD-L1 inhibitor and the latest in the broader class of PD-1/PD-L1–targeted biologics approved by the FDA in the last two years.
Atezolizumab is indicated for patients with locally advanced or metastatic urothelial carcinoma whose disease has worsened during or after platinum-containing chemotherapy, or within 12 months after receiving platinum-containing chemotherapy, either before (neoadjuvant) or after (adjuvant) surgical treatment. Urothelial carcinoma is the most common type of bladder cancer. The National Cancer Institute estimates that 76,960 new cases of bladder cancer and 16,390 deaths from the disease will occur in 2016.
The safety and efficacy of atezolizumab were evaluated in a single-arm clinical trial involving 310 patients with locally advanced or metastatic urothelial carcinoma. This study determined the percentage of patients who experienced complete or partial shrinkage of their tumors (the objective response rate). The study also looked at the difference in effect based on “positive” versus “negative” expression of the PD-L1 protein on patients’ tumor-infiltrating immune cells. Fifteen percent of the participants experienced at least partial shrinkage of their tumors, an effect that lasted from 2.1 months to 13.8 months at the time of the response analysis. Among patients who were classified as “positive” for PD-L1 expression, 26% experienced a tumor response, compared with 9.5% of patients who were classified as “negative” for PD-L1 expression.
The greater treatment effect in patients who were classified as “positive” for PD-L1 expression suggests that the level of PD-L1 expression in tumor-infiltrating immune cells may help identify patients who are more likely to respond to treatment with atezolizumab. Therefore, the FDA has also approved the Ventana PD-L1 (SP142) assay (Ventana Medical Systems) to detect levels of PD-L1 protein expression on patients’ tumor-infiltrating immune cells and to help physicians determine which patients may benefit most from treatment with atezolizumab.
The most common adverse effects of treatment with atezolizumab included fatigue, decreased appetite, nausea, urinary tract infection, pyrexia, and constipation. Atezolizumab also has the potential to cause infection and serious adverse events that result from the drug’s immune-mediated effects. The latter events may involve healthy organs, including the lung, colon, and endocrine system.
Source: FDA; May 18, 2016.