- Seattle Genetics and Astellas Pharma on Thursday said their experimental bladder cancer treatment enfortumab vedotin helped to shrink tumors in a Phase 2 bladder cancer study.
- Topline results from the first cohort of the trial showed the drug led to a 44% response rate among patients with locally advanced or metastatic urothelial cancer who were previously treated with chemotherapy and a checkpoint inhibitor. Duration of response was similar to what was observed in a Phase 1 trial.
- The companies plan to use the data to file for Food and Drug Administration approval later this year. Results of the study will be presented at an upcoming medical meeting.
The treatment's performance in the study beat expectations of investors on Wall Street, who were generally estimating a response rate of 30% or higher, SVB Leerink analyst Andrew Berens wrote in a note to clients.
The data "should impress even the skeptics," wrote RBC Capital Markets analyst Kennen MacKay. The 44% response rate surpasses the rates observed in studies of checkpoint inhibitor therapies in an earlier phase of treatment, he said.
Company executives focused on the continued need for treatment options despite approval of several checkpoint inhibitors in the tumor type.
"Despite recent approvals of multiple checkpoint inhibitors for previously treated locally advanced or metastatic urothelial cancer, there remains a high unmet need for effective treatments upon progression after initial chemotherapy and immunotherapy," said Roger Dansey, chief medical officer at Seattle Genetics, in the company’s statement.
In recent years, checkpoint inhibitors by Merck & Co., Bristol-Myers Squibb, Roche, Pfizer and AstraZeneca have all been approved to treat bladder cancer.
Seattle Genetics and Astellas already have a Phase 3 trial underway to serve as a confirmatory study. Based on earlier Phase 1 results, the FDA gave the drug a Breakthrough Therapy designation, allowing for a speedier review process.
Enfortumab vedotin targets a molecule known as Nectin-4, which is present on many solid tumors including bladder. An antibody-drug conjugate, the therapy attaches a toxic, chemical payload to a monoclonal antibody designed to seek out cancer cells expressing Nectin-4.
The companies are also studying whether Enfortumab vedotin can be used as an earlier treatment for patients with locally advanced or metastatic forms of urothelial cancer, the most common type of bladder cancer. About 549,000 people around the world were diagnosed with bladder cancer last year, and about 200,000 died, the companies said.
Analysts said they will look next for details on the duration of the tumor response and the drug's safety profile. According to the companies, the most common adverse events observed were fatigue, alopecia, decreased appetite, rash and peripheral neuropathy.