The FDA on Monday awarded accelerated approval to AstraZeneca's PD-L1 inhibitor Imfinzi (durvalumab) for the treatment of certain patients with locally advanced or metastatic urothelial carcinoma. Specifically, the therapy is indicated for patients who experience disease progression during or after platinum-containing chemotherapy, or whose disease progressed within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy. The agency also approved Roche's Ventana PD-L1 assay as a complementary diagnostic for assessing PD-L1 protein levels in urothelial carcinoma tissue.
AstraZeneca CEO Pascal Soriot remarked "this first approval for Imfinzi is an important milestone in our return to growth and brings us another step closer to our goal of redefining the way cancer is treated." The company said the average list price for Imfinzi, which is administered intravenously every two weeks, is approximately $15 000 a month, but varies according to the patient's weight.
Approval of the drug was backed by data from Study 1108 , a Phase I/II single-arm trial of 182 patients with locally advanced or metastatic urothelial carcinoma whose disease progressed after prior platinum-containing chemotherapy. Results demonstrated that Imfinzi had an objective response rate of 17 percent in all evaluable patients, regardless of PD-L1 status, and 26.3 percent in those with PD-L1 high-expressing tumours, as determined by the Ventana PD-L1 test. AstraZeneca noted that approximately 14.3 percent of all evaluable patients achieved partial response and 2.7 percent achieved complete response. Further, the company said that among the total 31 responding patients, 14 patients had ongoing responses of at least six months, while five patients had ongoing responses of 12 months or longer.
Imfinzi was previously granted priority review  and breakthrough therapy  status by the FDA for urothelial carcinoma in patients who exhibited disease progression during or after at least one standard platinum-containing regimen. The drug is also being investigated as monotherapy and in combination with AstraZeneca's CTLA-4 monoclonal antibody tremelimumab in the Phase III DANUBE study as a potential first-line treatment for patients with metastatic urothelial carcinoma.
Last November, the FDA permitted  AstraZeneca to resume enrolment in clinical studies examining Imfinzi, alone and in combination with tremelimumab or other therapies, for the treatment of head and neck squamous cell carcinoma. The agency had previously placed a partial clinical hold on the studies in response to bleeding events.