medwireNews: US researchers have found limited use of erdafitinib, the first targeted therapy approved for urothelial cancer, in routine care.
They highlight that use of the pan-FGFR inhibitor was low even though real-world survival outcomes were comparable with those from clinical trials, and suggest “drug toxicity, drug cost limiting access, paucity of data on optimal treatment sequencing, and inadequate FGFR testing” as possible reasons.
Vivek Nimgaonkar and colleagues from the University of Pennsylvania in Philadelphia drew on the Flatiron Health database to identify 761 advanced urothelial cancer patients who progressed after first-line platinum-based chemotherapy and initiated another treatment between April 1, 2019 and September 1, 2021.
Just under half (45.1%) of the patients underwent FGFR testing; 20.7% of the 343 tested patients had a susceptible FGFR3 alteration or FGFR2/3 fusion, and 42.3% of the 71 with such an alteration initiated treatment with erdafitinib.
Following the April 2019 approval by the US FDA of erdafitinib in the second or later line, the number of patients who underwent FGFR testing rose from around 25 at the start of quarter 2 of 2019 to just over 60 at the start of quarter 1 2020 and around 75 at the start of quarter 2 of 2021.
But “erdafitinib initiation remained low among patients with FGFR alterations,” with the peak of uptake being at the start of quarter 1 in 2020 when around 10 patients received erdafitinib, report the investigators in a research letter to JAMA Oncology.
They also compared monthly uptake rates of erdafitinib with those of atezolizumab in the 6 months following the approval of each drug (April 2019 and May 2016, respectively), and found that erdafitinib uptake was significantly lower.
Among all comers, the overall uptake rate of erdafitinib was 0.8%, while it was 3.9% for those expected to harbor FGFR alterations. The uptake rate for atezolizumab was a significantly higher 16.8%.
Kaplan–Meier analysis gave an estimated overall survival time of 8.97 months in the Flatiron database population; this did not differ significantly from the 10.50 months estimated for the participants of the BLC2001 trial.
Nimgaonkar and co-researchers conclude that “[f]urther study is required to identify barriers to biomarker testing and erdafitinib use and to explore the potential for blood-based testing to augment identification of susceptible FGFR alterations and improve turnaround times, as seen for other tumors.”
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