Phase 1/1b open-label, dose-escalation study of fruquintinib in patients with advanced solid tumors in the United States

This open-label, phase 1/1b study was conducted to evaluate the safety, tolerability, and pharmacokinetics (PK) of fruquintinib in United States (U.S.) patients to confirm the recommended phase 2 dose (RP2D) established in China. Patients with advanced solid tumors who had progressed on approved systemic therapy, were enrolled into 2 successive dose escalation cohorts, fruquintinib 3 mg (n = 7) or 5 mg (n = 7), orally, once daily (QD), 3 weeks on and 1 week off (3/1) with a 3 + 3 design followed by a dose expansion cohort at the RP2D 5 mg dose (n = 6). PK samples were collected on Days 1, 14, and 21 (Cycle 1). One of 6 dose-limiting toxicity (DLT)-evaluable patients in the 3 mg cohort had a DLT of grade 4 hypertension; there were no DLTs in the 5 mg cohort. The RP2D was confirmed to be 5 mg QD 3/1. All 20 patients experienced a treatment-emergent adverse event; grade ≥ 3 in 5 (71.4%; 3 mg dose) and 12 (92.3%; 5 mg dose) patients. Two patients had a confirmed partial response. After single and multiple doses, median peak plasma concentrations occurred at 2 h post-dose. Steady-state was achieved after 14 days of QD dosing with systemic exposure four-fold higher than that after a single dose. Fruquintinib was well tolerated, and the safety and PK profile at the 5 mg RP2D in U.S. patients with advanced solid tumors was consistent with dose-finding studies in China. Preliminary anticancer activity was observed. This study is registered at Clinicaltrials.gov NCT03251378. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10637-023-01395-y.