A phase I pharmacokinetic study of HMN-214, a novel oral stilbene derivative with polo-like kinase-1-interacting properties, in patients with advanced solid tumors

Purpose: HMN-214 is an oral prodrug of HMN-176, a stilbene derivative that interferes with the subcellular spatial location of polo-like kinase-1, a serine/threonine kinase that regulates critical mitotic events. We conducted a dose escalation study of HMN-214 in patients with advanced cancer to assess the safety profile and pharmacokinetics of HMN-214 and to establish the maximum tolerated dose. Experimental Design: Thirty-three patients were enrolled onto four dosing cohorts of HMN-214 from 3 to 9.9 mg/m²/d using a continuous 21-day dosing schedule every 28 days, with pharmacokinetic sampling during cycle 1. Results: A severe myalgia/bone pain syndrome and hyperglycemia were dose-limiting toxicities at 9.9 mg/m²/d. A dose reduction and separate enrollment by pretreatment status (lightly versus heavily pretreated) was undertaken, with one dose-limiting toxicity (grade 3 bone pain) at 8 mg/m²/d. The maximum tolerated dose was defined as 8 mg/m ²/d for both treatment cohorts. Dose-proportional increases were observed in AUC but not C_max. There was no accumulation of HMN-176, the metabolite of HMN-214, with repeated dosing. Seven of 29 patients had stable disease as best tumor response, including 6-month stable disease in a heavily pretreated breast cancer patient. A transient decline in carcinoembryonic antigen in a patient with colorectal cancer was noted. Conclusions: The maximum tolerated dose and recommended phase II dose of HMN-214 when administered on this schedule was 8 mg/m²/d regardless of pretreatment status. Further development of HMN-214 will focus on patient populations for which high expression of polo-like kinase-1 is seen (i.e., prostate and pancreatic cancer patients).