A phase I trial of the proteosome inhibitor PS-341 in combination with carboplatin in platinum and taxane resistant ovarian cancer patinets
5558 Background. PS-341 (Millenium Pharmaceuticals, Inc.), a proteosome inhibitor, affects p53, NFκB, cell adhesion molecules, and sensitivity to cytotoxic agents to promote apoptosis and inhibit metastasis in cancer cells. PS-341 alone rarely causes myelosupression or renal toxicity, and therefore is an attractive agent to use in combination with cytotoxic chemotherapy. This phase I study evaluates the safety, dose-limiting toxicities (DLTs), and optimal dose of PS-341 when combined with carboplatin in ovarian cancer patients with recurrent, platinum- and taxane-resistant disease. Methods: After IRB approval, patients with recurrent ovarian cancer, platinum and taxane resistant (progression on platinum and/or taxane therapy or recurrence within 6 months of completing platinum and/or taxane therapy), measurable disease, and performance status 0–2 were eligible and enrolled after giving informed consent. As guided by toxicity and pharmacokinetic data from single-agent phase I trials, PS-341 was administered on days 1, 4, 8, and 11 by IV push every 28 days with carboplatin (AUC 5) on day 1. Four dose levels were evaluated: 0.8, 1.0, 1.3, and 1.5 mg/m2. Dose was escalated if 0 of 3 or 1 of 6 patients had a DLT. The MTD was defined as 2 or more patients out of 6 with a DLT. Results: 21 women (median age 63, range 43–83), were treated with carboplatin and PS-341 at 0.8mg/ m2 (n=6), 1.0 mg/m2 (n=3), 1.3 mg/m2 (n=6), or 1.5 mg/m2. (n=6). At each level, respectively, there were 1, 0, 1, and 3 DLT’s attributable to PS- 341; all were grade 3, consisting of fatigue (n=3), nausea/vomiting/dehydration (n=1), and anorexia/dehydration/syncope (n=1). There were no Grade 4 toxicities. Common grade 2 toxicities included fatigue (n=12), nausea (n=10), anorexia, anemia, and dyspnea (n=7 each). 18 patients evaluable for response had stable disease (SD) or progression of disease (PD): at 0.8 mg/m2, SD=2, PD=3; at 1.0 mg/m2, PD=3; at 1.3 mg/m2, SD=3, PD=3; at 1.5 mg/m2, SD=3, PD=1. Median duration of stable disease was 4 months (range 3–10). Conclusions: The recommended dose of PS-341 in combination is 1.3 mg/m2. Treatment was well-tolerated with reversible side effects and no grade 4 toxicities, and at the optimal dose, there was a 50% rate of stable disease. No significant financial relationships to disclose.