It has been an especially exciting time for our Genitourinary (GU) Oncology Program. Our team’s bladder (urothelial) cancer research recently made its way into two prestigious medical journals, with both studies highlighting erdafitinib – an oral inhibitor of fibroblast growth factor receptor (FGFR) – as an encouraging therapeutic option for the disease.
FGFR gene alterations are common in urothelial carcinoma and may be associated with low sensitivity to immunotherapy.
In a phase II study of 99 adults with locally advanced or metastatic urothelial carcinoma harboring FGFR gene alterations, Dr. Scott Tagawa and colleagues found erdafitinib to demonstrate impressive tumor control and tolerability. Forty percent of patients responded to the drug, and among the 22 patients who had previously received immunotherapy without success, the response rate jumped to 59 percent.
“While not yet confirmed by randomized trial results, the fact that these patients with the unique molecular tumor selection were responsive to erdafitinib and resistant to prior lines of standard therapy makes this a pivotal study,” said Dr. Tagawa. “It’s wonderful to now have this option available for our patients early while awaiting results of the confirmatory randomized trial. It highlights the importance of genomic tumor testing.”
The research group’s findings were published in the New England Journal of Medicine and led to accelerated approval of erdafitinib as the first targeted drug for urothelial carcinoma from the United States Food and Drug Administration (FDA).
In addition to the use of next-generation sequencing of tumors to more precisely select those most likely to respond, the standard erdafitinib regimen also utilizes individualized dosing. Erdafitinib, partly depending on the dose used, is shown to induce increased phosphorus levels in the blood. As blood phosphorus levels are related to targeting of the key pathway (FGFR), the dose of erdafitinib is increased if phosphorus levels do not significantly increase in the absence of any significant side effect. In a retrospective analysis presented at the 2019 European Society of Medical Oncology (ESMO) annual meeting, erdafitinib-treated patients with increased blood phosphorus levels had improved outcomes.
Under the leadership of Dr. Bishoy Faltas, an in-depth analysis of the nuanced molecular characteristics of upper-tract urothelial carcinoma (UTUC) – an aggressive cancer occurring in the lining of the ureter and kidney – supports that erdafitinib has potential to improve the effectiveness of immunotherapy in this patient population.
Whole-exome and RNA sequencing of UTUC patient tumors yielded a number of insights into the biology of the disease – chiefly that it has low immune cells (T cells) and high expression of FGFR3. The research team found that inhibiting FGFR3 with erdafitinib increased the activity of BST2, a gene associated with immune system activation. Thus, combining FGFR3 inhibitors such as erdafitinib with a class of immunotherapy drugs called PD-1/PD-L1 inhibitors can serve as a viable treatment strategy for UTUC in the future.
“By inhibiting FGFR3, we are able to stimulate genes that are associated with activation of the anti-tumor immune response,” said Dr. Faltas. “In the future, we could potentially use this strategy to reverse the T-cell depletion in these tumors.”
Findings from Dr. Faltas et al. were published in Nature Communications.
Erdafitinib is under further investigation and development in an ongoing clinical trial at Weill Cornell Medicine and NewYork-Presbyterian.
We are proud to draw upon our longstanding expertise in the bladder cancer field to lead advancements in the understanding and care of this disease, and we hope that sharing our findings will prompt additional discoveries.
What's New in GU? 