Safety, tolerability and pharmacokinetics of oral administration of GW786034 in pts with solid tumors

Abstract

3012 Background: GW786034 is a tyrosine kinase inhibitor of VEGFR-1,-2 and -3, PDGFR-α and -β, and c-kit. Plasma trough concentrations above ∼ 18 μg/mL were required for optimal anti-tumor and anti-angiogenic activity in animal models. Methods: Pts with solid tumors were enrolled in an ongoing Phase I study. Safety (including daily BP monitoring), single- and multiple-dose PK, biomarkers, and clinical activity were evaluated. Response was assessed by RECIST. Results: 43 pts were enrolled in the dose escalation phase at doses ranging from 50 mg 3 times weekly to 2000 mg daily (qd) in 11 cohorts. Mean half-life was ∼ 35 hrs. Accumulation of 1.5 - 3 fold and Cmax/Cmin of ∼ 2 were observed at steady-state. Maximal exposure with trough concentrations (C24) > 18 μg/mL were observed after doses ≥ 800 mg qd. MTD was not achieved. The most frequent drug related AEs were NCI CTC2, Gr 1 and 2: nausea (Gr 1/2 n=15, Gr 3 n=1), diarrhea (Gr 1/2 n=15), fatigue (Gr 1/2 n=12, Gr 3 n=1), HTN (Gr 1/2 n=6, Gr 3 n=6), anorexia (Gr 1/2 n=12), and vomiting (Gr 1/2 n=9, Gr 3 n=1). Hair depigmentation was observed (n=6/14) at doses of ≥ 800 mg. The greatest magnitude in BP change was observed at 800 mg and correlated with C24 of > 20 μg/mL. HTN was amenable to treatment and was reversible upon cessation of GW786034. No pts were withdrawn from study solely due to HTN. One of 3 pts treated at 2000 mg qd developed Gr 3 fatigue (DLT). Tumor shrinkage (minimal response) was observed in all 3 pts with renal cell cancer treated at ≥ 800 mg qd and in one pt with Hurthel cell tumor. Six additional pts (melanoma n=1, sarcoma n=3, lung n=1, neuroendocrine n=1) remained on study for ≥ 6 mos with SD. Conclusion: GW786034 was generally well tolerated with preliminary evidence of anti-tumor activity in cancer patients. HTN and hair depigmentation were indicative of VEGFR and c-kit modulation. Two dose cohorts (800 mg qd and 300 mg bid) are being expanded. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration GlaxoSmithKline GlaxoSmithKline GlaxoSmithKline