Phase 1 study of ombrabulin in combination with docetaxel and cisplatin in Japanese patients with advanced solid tumors.

Background: The combination use of the vascular disrupting agent ombrabulin with chemotherapeutic agents was previously shown to be highly synergistic in preclinical models.

Methods: In this dose-escalation study of ombrabulin (15.5-35 mg/m2) in combination with docetaxel (60 or 75 mg/m2) and cisplatin (75 mg/m2), agents were administered 24 h apart every 3 weeks to Japanese patients with advanced solid tumors. The study was designed and conducted in a 3 + 3 manner. Safety, tumor response and pharmacokinetics were evaluated.

Results: Eleven patients with non small cell lung cancer as the primary tumor were treated. Two patients out of five had dose limiting toxicities (DLTs) in Cycle 1 at the starting doses of ombrabulin 15.5 mg/m2, docetaxel 60 mg/m2 and cisplatin 75 mg/m2. Thus, dose escalation was terminated. The first dose level was re-evaluated in six patients who received prophylactic granulocyte-colony stimulating factor (G-CSF). However, because of the occurrence of DLTs in Cycle 1 in two patients out of six, the study was led to the premature termination without pursued upper dose level. Partial response was observed in four patients out of 11. Pharmacokinetic parameters of ombrabulin and cisplatin were not altered in this combination treatment, while docetaxel clearance decreased by ~40% compared to that observed with docetaxel monotherapy at the same dose (60 mg/m2).

Conclusion: A combination regimen of ombrabulin with cisplatin and docetaxel was not feasible for Japanese patients owing to the occurrence of hematological and non-hematological DLTs at the initial dose level.

Clinical Trial Registration Id: ClinicalTrials.gov number, NCT01095302.