A phase 1 study of the heat shock protein 90 inhibitor retaspimycin hydrochloride (IPI-504) in patients with gastrointestinal stromal tumors or soft tissue sarcomas
Mené sur 37 patients atteints d'une tumeur stromale gastro-intestinale et 17 patients atteints d'une autre forme de sarcome des tissus mous métastatique et/ou non résécable, cet essai de phase I évalue la toxicité et la dose maximale tolérée d'un composé appelé IPI-504, un inhibiteur de la protéine de choc thermique Hsp90
Purpose: Heat shock protein 90 (Hsp90) is required for the proper folding, function, and stability of various client proteins, two of which (KIT and PDGFRα) are critical in the pathogenesis and progression of gastrointestinal stromal tumors (GIST). This phase 1 study investigated the safety and maximum tolerated dose (MTD) of retaspimycin hydrochloride (IPI-504), a novel potent and selective Hsp90 inhibitor, in patients with metastatic and/or unresectable GIST or other soft-tissue sarcomas (STS). Experimental Design: IPI-504 was administered intravenously at doses ranging from 90 to 500 mg/m2 twice weekly for 2 weeks on/1 week off. Safety, pharmacokinetic, and pharmacodynamic profiles were determined. Response was assessed by Response Evaluation Criteria for Solid Tumors (RECIST) 1.0 and optionally via 18-fluorodeoxyglucose positron emission tomography (18-FDG-PET)imaging. Results: Fifty-four patients received IPI-504; 37 with GIST and 17 with other STS. The MTD was 400 mg/m2 twice weekly for 2 weeks on/1 week off. Common related adverse events were fatigue (59%), headache (44%), and nausea (43%). Exposure to IPI-504, 17-AAG, and 17-AG increased with IPI-504 dose. Stable disease (SD) was observed in 70% (26/37) of patients with GIST and 59% (10/17) of patients with STS. There was one confirmed partial response (PR) in a patient with GIST and one PR in a patient with liposarcoma. Metabolic partial responses occurred in 11/29 (38%) of GIST patients. Conclusions: In this study of advanced GIST or other STS, IPI-504 was generally well-tolerated with some evidence of anti-tumor activity, serving as a clinical proof-of-concept that HSP90 inhibition remains a promising strategy.