A Phase Ib/II Study of Pemigatinib in Combination with Paclitaxel in Patients with Gastric Cancer with FGFs/FGFRs Alterations

Purpose: Pemigatinib is a selective inhibitor of fibroblast growth factor receptors (FGFR) 1-3 with demonstrated activity in tumors harboring FGFR2 fusions or amplifications. This phase Ib/II trial assessed the efficacy and safety of pemigatinib in combination with paclitaxel in patients with recurrent or advanced gastric cancer exhibiting FGFs/FGFRs alterations. Materials and Methods: Patients with gastric cancer harboring FGFs/FGFRs aberrations who experienced progression following first-line therapy were enrolled. The phase Ib component established the recommended phase II dose (RP2D); the phase II component evaluated clinical efficacy. Results: Twelve patients were enrolled. The RP2D was determined as pemigatinib 13.5 mg/day (days 1-21) plus paclitaxel 80 mg/m² (days 1, 8, 15) every 4 weeks. Median progression-free and overall survival were 4.4 and 10.5 months, respectively. Patients with FGFR2 amplification (n=6) exhibited prolonged progression-free survival (6.5 vs. 3.5 months, p=0.049), while overall survival did not differ significantly. The objective response and disease control rates were 33.3% and 91.7%, respectively. The most frequent treatment-related adverse events were neutropenia (83.3%, grade ≥3: 58.3%) and hyperphosphatemia (83.3%, grade ≥3: 33.3%). Conclusion: Pemigatinib plus paclitaxel demonstrated antitumor activity with an acceptable safety profile in FGFR2-amplified gastric cancer. Further investigation is warranted to elucidate resistance mechanisms and validate these findings in larger cohorts.