On September 30, Taiho Oncology published a press release stating that its targeted therapy Lytgobi (futibatinib) was approved by the US Food and Drug Administration (FDA) for use in adult patients with previously treated, unresectable, locally advanced, or metastatic intrahepatic cholangiocarcinoma (iCCA) harbouring fibroblast growth factor receptor 2 (FGFR2) gene fusions or other rearrangements. Accelerated approval was granted based on positive results from the pivotal Phase II FOENIX-CCA2 trial in which Lytgobi monotherapy was studied in patients with iCCA and FGFR2 gene rearrangements including fusions.
In the global FOENIX-CCA2 trial, 103 patients with previously treated, unresectable, locally advanced, or metastatic iCCA harbouring FGFR2 gene rearrangements including fusions were orally administered 20mg of Lytgobi once daily until disease progression or unacceptable toxicity. The study met its primary endpoint with an objective response rate (ORR) of 42%, as measured by an independent central review according to RECIST v1.1. The median duration of response (DOR) was 9.7 months, with 72% of responses lasting at least 6 months. The most common (≥20%) adverse reactions included diarrhoea, fatigue, dry mouth, and vomiting.
Bile duct cancer, or cholangiocarcinoma, is an aggressive cancer that can occur both inside the liver (intrahepatic) and outside the liver (extrahepatic). Approximately 8,000 people in the US are diagnosed with it each year and the estimated number of cases is expected to be higher than the reported number as the diagnosis of this cancer can be misattributed to other tumours. About 20% of all cases are intrahepatic, with the five-year survival rate being 9%, and 10–16% of these iCCA patients have FGFR2 gene rearrangements. The inhibition of FGFR inhibits various downstream pathways necessary for tumour growth. There are currently two alternative FGFR inhibitors that have been approved for use in this subpopulation in the US, Incyte’s Pemazyre (pemigatinib) and QED Therapeutics’s Truseltiq (infigratinib phosphate). However, Taiho believes that Lytgobi’s mechanism of action (MOA) will set its drug apart from its competitors. While Pemazyre and Truseltiq are reversible ATP-competitive inhibitors, Lytgobi covalently and irreversibly binds to FGFR, thus inhibiting FGFR-related signaling pathways for a longer period. However, safety issues remain a concern in this drug class, with warnings of eye toxicity, hyperphosphatemia, and embryo-fetal toxicity being listed as a risk with the use of Lytgobi.
GlobalData does not expect Lytgobi to become the best-selling drug in this indication. According to GlobalData’s consensus analyst forecasts, Lytgobi’s sales in this indication in the US are expected to reach $50 million by 2028, compared to Pemazyre’s sales of $108 million, which gained a first-to-market advantage in 2020, and its sales are not expected to be eroded by generic drugs due to patent expiry in 2035. According to GlobalData’s PharmOnline International (POLI) database, the manufacturer prices of Pemazyre and Truseltiq are $17,510 and $22,575, respectively, in the US. Taiho has not yet announced any pricing information about Lytgobi, but a price closer to that of second-to-market Truseltiq can be expected, with a premium applied due to Lytgobi’s novel MOA in this subpopulation. Nonetheless, this approval comes as positive news to cholangiocarcinoma patients who have few therapeutic options, but continued approval may depend on verifying the clinical benefit to patients in a confirmatory trial.