Abstract
Fibroblast growth factor receptors (FGFRs) are a highly conserved family of transmembrane receptor tyrosine kinases with multiple roles in the regulation of key cellular processes. Specific FGFR mutations have been observed in several types of cancers, including gastric carcinoma and cholangiocarcinoma. Dose escalation data of 24 Japanese patients with solid tumors treated with Tasurgratinib (previously known as E7090), a potent, selective FGFR1-3 inhibitor, was reported in a phase I, first-in-human, single-center study. Based on the safety, pharmacokinetic, and pharmacodynamic profiles observed in this study, the recommended dose of 140 mg once daily was selected for the expansion part (Part 2), a multicenter expansion of the dose-finding study restricted to patients with tumors harboring FGFR gene alterations. Safety and preliminary efficacy were assessed in Part 2. Pharmacodynamic pharmacogenomic markers (serum phosphate, FGF23, and 1,25-(OH)(2)-vitamin D, circulating tumor DNA) and pharmacokinetic profiles were also evaluated. A total of 16 patients were enrolled in Part 2, six with cholangiocarcinoma and 10 with gastric cancer. The most common treatment-emergent adverse events were hyperphosphatemia, palmar-plantar erythrodysesthesia syndrome, and paronychia. Five partial responses (83.3%) in cholangiocarcinoma patients and one partial response (11.1%) in gastric cancer patients were observed; median progression-free survival was 8.26 months (95% confidence interval [CI] 3.84, not evaluable [NE]) and 3.25 months (95% CI 0.95, 4.86), and overall survival was 22.49 months (95% CI 6.37, NE) and 4.27 months (95% CI 2.23, 7.95), respectively, in the two groups. In conclusion, Tasurgratinib 140 mg has a tolerable safety profile with good clinical efficacy in patients with cholangiocarcinoma harboring FGFR2 gene rearrangements.