Sunesis Pharmaceuticals, Inc. has announced a presentation of updated interim results from an ongoing Phase 2 clinical trial demonstrating that the Company's lead product candidate, voreloxin, shows promising efficacy and safety as a single agent in patients with platinum-resistant ovarian cancer.
Ovarian cancer remains an unmet medical need with high recurrence rates, and the majority of patients ultimately become resistant to platinum-based therapies. These data show encouraging durable anti-tumor activity in the 48 mg/m2 cohort, as measured by partial and complete responses, and preliminary progression-free survival (PFS). Voreloxin has been generally well tolerated at dose levels of 48 mg/m2 and 60 mg/m2.
"Voreloxin continues to demonstrate promising clinical activity in a vastly underserved patient population," said William McGuire, M.D., Medical Director of the Harry and Jeanette Weinberg Cancer Institute at Franklin Square and principal investigator for the Phase 2 clinical trial. "I am encouraged by the preliminary data from the 48 mg/m2 cohort. When compared to other commercially available drugs that are used in the platinum-resistant setting, voreloxin has a similar response rate and a reasonable toxicity profile."
"The preliminary data from the 60 mg/m2 cohort suggests activity similar to that of the 48 mg/m2 cohort. This is expected since the weekly dose intensity is approximately the same. We are encouraged by the pace of enrollment in the 75 mg/m2 cohort and anticipate initial response and safety data from this cohort in the spring of next year," said Dr. Mary Bolton, Vice President, Clinical Development at Sunesis.
The ongoing Phase 2 trial is an open-label, multi-center study of voreloxin as a single agent in recurrent ovarian cancer patients who have platinum-resistant disease, defined as progression within six months of completing platinum-based chemotherapy or progression while on platinum-based therapy. To date, over 120 patients have enrolled in the trial, with enrollment completed in the 48 mg/m2 cohort dosed every three weeks and the 60 mg/m2 cohort dosed every four weeks. In the 48 mg/m2 cohort, of the 65 women evaluable for best response using GOG-RECIST criteria, two patients had a complete response, five patients had partial responses and 46 patients achieved stable disease. Thirty patients (46%) achieved disease control, defined as stable disease for 90 days or more or a complete or partial response. The preliminary median PFS was 82 days, or 11.7 weeks, at the 48 mg/m2 dose. Six patients remain on study in this dose cohort.
In the 60 mg/m2 cohort, the Company reported early efficacy data for 32 of the 35 patients treated at this dose who were evaluable for best response using GOG-RECIST criteria. Of these 32 patients, preliminary data show one patient had a complete response, two patients had partial responses and 20 patients achieved stable disease. The data at the 60 mg/m2 dose are not yet mature enough to calculate disease control or PFS. Thirteen patients remain on study in this dose cohort.
Voreloxin has been generally well tolerated in the platinum-resistant ovarian cancer population in both cohorts, with a total incidence of febrile neutropenia below 10%. This safety profile supported increasing the dose intensity by more than 25% to 75 mg/m2 dosed every four weeks. The Company has enrolled 22 of 30 patients in the 75 mg/m2 cohort and is on track to complete enrollment by the end of 2008. Additional clinical data from all three cohorts are expected in the first half of 2009.
All patients enrolled in the trial have previously failed treatment with platinum-containing regimens in less than 6 months, and approximately one-third of the patients across the dosing cohorts have also failed prior treatment with doxorubicin HCl liposome injection (Doxil(R)). Both platinum-resistant and Doxil-failure patients in this trial have responded to voreloxin therapy.
These data were discussed in a poster session on October 25, 2008, entitled "A Phase 2 Trial of Voreloxin (SNS-595) in Women with Platinum-Resistant Ovarian Cancer" Abstract 1607 at the 12th Biennial Meeting of the International Gynecologic Cancer Society (IGCS) in Bangkok, Thailand.