Targeted therapy with erdafitinib, a tyrosine kinase inhibitor of the fibroblast growth factor receptor (FGFR) gene, achieved a 40% objective tumor response rate in patients with locally advanced and metastatic urothelial cancers with FGFR3 gene mutations, according to the findings of a phase 2 trial published July 25 in the New England Journal of Medicine.

Trial results led to FDA approval of erdafitinib (Balversa, Janssen Pharmaceutical) in April, making the drug the first targeted therapy approved for treating locally advanced or metastatic urothelial cancers with mutations in the FGFR2 or FGFR3 genes.

The trial enrolled 99 patients, of whom 43% received at least 2 previous courses of treatment and 79% had visceral metastases. In addition, 53% of patients had a creatinine clearance of less than 60 mL per minute. Patients received a median of 5 cycles of erdafitinib.

The rate of confirmed response to the drug was 40%, including 3% with a complete response and 37% with a partial response, principal investigator Arlene Siefker-Radtke, MD, of The University of Texas MD Anderson Cancer Center in Houston, and colleagues reported.

Twenty-two patients had received previous immunotherapy, and in this group the confirmed response rate was 59%.

The median duration of progression-free and overall survival was 5.5 months and 13.8 months, respectively.

“We were gratified to see a 40% response rate in patients treated on this trial,” Dr Siefker-Radtke, Professor of Genitourinary Medical Oncology, said in an MD Anderson press release. “Not only did it work well in patients with lymph node metastases, but also in patients with high volume and very aggressive disease.”

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She added: With the recent approval of erdafitinib for the treatment of patients with FGFR3-mutant urothelial cancers, we now have an additional agent to add to our armamentarium.”

Results showed that 46% of patients experienced grade 3 or higher treatment-related adverse events (AEs), which were managed with dose adjustments. In addition, 13% of patients discontinued treatment because of AEs. No treatment-related deaths occurred, according to the investigators.

The study was funded by Janssen Research and Development. Dr Siefker-Radtke serves on the scientific advisory committee for Janssen.

A phase 3 trial is underway comparing erdafitinib with chemotherapy or the immune checkpoint inhibitor pembrolizumab in patients with metastatic urothelial cancer and FGFR3 mutations.

Reference

Loriot Y, Necchi A, Park SH, et al. Erdafitinib in locally advanced or metastatic urothelial carcinoma. N Engl J Med. 2019;381:338-348. doi: 10.1056/NEJMoa1817323