Phase 2 study of futibatinib in patients with gastric or gastroesophageal junction cancer harboring FGFR2 amplifications.

[BACKGROUND AND AIMS] Aberrant fibroblast growth factor receptor (FGFR)-driven signaling, predominantly arising from FGFR2 amplification, plays a key role in gastric cancer pathogenesis. This open-label, phase 2 study evaluated the efficacy and safety of futibatinib, an irreversible FGFR1-4 inhibitor, in patients with gastric or gastroesophageal junction (GEJ) cancer harboring FGFR2 amplifications.

[METHODS] Patients were treated with futibatinib 20 mg orally once daily in a 28-day cycle. The primary endpoint was objective response rate (ORR) per independent central review. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety.

[RESULTS] Among 28 treated patients, the ORR per independent central review was 17.9 %, comprising five patients with a partial response (median duration of response, 3.9 months), and an additional nine patients with stable disease for a disease control rate of 50.0 %. Median PFS per independent central review and median OS were 2.9 and 5.9 months, respectively. The most common treatment-related adverse events (any grade) were hyperphosphatemia (89.3 %), decreased appetite (32.1 %), and increased aspartate aminotransferase (21.4 %). Only one (3.6 %) patient discontinued study treatment due to an adverse event. Futibatinib demonstrated modest antitumor activity with a safety profile consistent with previous reports in patients with gastric or GEJ cancer harboring FGFR2 amplifications, potentially warranting further investigation.