Phase I Dose-Escalation Trial of the Oral Investigational Hedgehog Signaling Pathway Inhibitor TAK-441 in Patients with Advanced Solid Tumors

Purpose: This first-in-human study assessed safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity of single and multiple doses of TAK-441, an investigational inhibitor of the Hedgehog signaling pathway. Experimental Design: Patients with advanced, solid tumors received daily oral TAK-441 (50-1,600 mg/day); daily dose was doubled in each subsequent cohort until the maximum tolerated/ feasible dose (MTD/MFD) was reached. Blood was collected to evaluate TAK-441 plasma concentrations. Skin biopsies were obtained to evaluate suppression of the Hedgehog-regulated gene Gli1. Results: Thirty-four patients were enrolled (median age 59). The most common diagnoses were colorectal cancer (26%), basal cell carcinoma (BCC, 21%), and pancreatic cancer (9%). The MFD of 1,600 mg/day (based on tablet size and strength) was considered the MTD. Dose-limiting toxicities included muscle spasms and fatigue. Grade >= 3 treatment-emergent adverse events, regardless of causality, occurred in 15 patients (44%), of which hyponatremia (n = 4) and fatigue (n = 3) were most common. Oral absorption was fairly rapid; median T-max was 2.0 to 4.0 hours after a single dose. Mean elimination half-life was 13.5 to 22.6 hours. Systemic exposure of TAK-441 based on the area under the plasma concentrationtime curve was linear across the dose range. Gli1 expression in skin biopsies was strongly inhibited at all dose levels. Best response was partial response (1 patient with BCC) and stable disease (7 patients with various solid tumors). Conclusions: TAK-441 was generally well tolerated up to MFD of 1,600 mg/day, with preliminary antitumor activity. Further study of TAK-441 may be appropriate in populations selected for tumors with ligand-dependent or independent Hedgehog signaling.