Experimental Drug Shows Rapid Tumor Shrinkage in Advanced Bladder Cancer

Bladder Cancer

A mid-stage treatment is showing significant promise in treating bladder cancer. An experimental drug developed by Astellas Pharma and Seattle Genetics rapidly shrank tumors in most patients, the companies announced this morning.

Tokyo-based Astellas and Washington-based Seattle Genetics said that the EV-201 trial assessing enfortumab vedotin demonstrated a 44% objective response rate in patients. Complete responses were observed in 12% of patients, the companies said, with the median duration of tumor response at 7.6 months. The treatment was open to patients diagnosed with locally advanced or metastatic urothelial cancer who had received previous treatment with a platinum-containing chemotherapy and a PD-1/L1 checkpoint inhibitor. Most responses occurred within the first cycle of treatment, and were observed across all pre-specified patient subgroups irrespective of lines of therapy, response to prior PD-1/L1 inhibitor, or presence of liver metastases, the companies said. Median overall survival (OS) was 11.7 months and the median progression-free survival was 5.8 months.

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The two companies said the responses were similar in the subgroups of patients analyzed, including those who had the worst prognosis, such as patients who had three or more previous lines of therapy, patients with liver metastases, and those who had not responded to a PD-1/L1 inhibitor. Astellas and Seattle Genetics noted that about 80% of people with this kind of cancer does not respond to treatment with checkpoint inhibitors and are desperately in need of additional treatment options.

The experimental drug, enfortumab vedotin is an investigational antibody-drug conjugate (ADC) that targets Nectin-4, a protein that is highly expressed in urothelial cancers. Enfortumab vedotin previously earned Breakthrough Therapy designation for patients with locally advanced or metastatic urothelial cancer whose disease has progressed during or following checkpoint inhibitor therapy. Based on the results of the EV-201 study, the two companies plan to submit a Biologics License Application for enfortumab vedotin to the U.S. Food and Drug Administration later this year to provide a new treatment option for these patients.

“Even with the recent introduction of new therapies, there remains a need for continued innovation in the treatment of urothelial cancer, and if approved, we hope to bring this potential treatment to physicians and patients as quickly as possible," Andrew Krivoshik, head of Oncology Therapeutic Area Head at Astellas said in a statement.

Seattle Genetics Chief Medical Officer Roger Dansey was also excited about the results. He said the companies are encouraged that enfortumab vedotin is the first novel therapy to demonstrate substantial clinical activity in the patients with this difficult-to-treat condition.

The data was presented at the American Society of Clinical Oncology as part of a late-breaking oral presentation.

A Phase III confirmatory study, EV-301, is ongoing and will be used to support global registrations. Additionally, another trial, EV-103, is being conducted to evaluate enfortumab vedotin in earlier lines of treatment for patients with locally advanced or metastatic urothelial cancer, including in combination with pembrolizumab and/or platinum chemotherapy in newly diagnosed patients as well as patients who progressed from earlier-stage disease.

There were no significant safety issues. Treatment-related adverse events that occurred in 40% or more of patients were fatigue, alopecia, rash, decreased appetite, taste distortion and peripheral neuropathy.

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