Voreloxin (SNS-595) Produces 48% Disease Stabilization in Treatment Resistant Ovarian Cancer Patients

Voreloxin (at a 48 mg/m² dosage) demonstrates single agent activity in advanced platinum-resistant ovarian cancer patients (24 patients with stable disease (SD) ≥90 days, 1 patent with complete response (CR), 5 patients with partial response (PR)) as evidenced by a 48% overall disease control rate (i.e., SD + PR + CR). The results are impressive because the disease control response population includes patients with primary and secondary platinum drug resistance who have failed prior treatment with pegylated liposomal doxorubicin (Doxil®, Caelyx®, Myocet®), gemcitabine (Gemzar®), topotecan (Hycamtin®), etoposide (Eposin®, Etopophos®, Vepesid®), bevacizumab (Avastin®), and/or other various experimental agents.

The H*O*P*E*™ weblog reported the early interim success of Voreloxin (formerly known as SNS-595) in Phase II clinical trial testing on March 15, 2008. Based upon an abstract presentation that will be made by Sunesis Pharmaceuticals today at the 2008 American Society of Clinical Oncology (ASCO) Annual Meeting, the success of Voreloxin continues, despite the fact that many of the ovarian cancer patients participating in the trial experienced significant drug/treatment resistance prior to enrollment.

Specifically, Voreloxin (at a 48 mg/m² dosage) demonstrates single agent activity in advanced platinum-resistant ovarian cancer patients (24 patients with stable disease (SD) ≥90 days, 1 patent with complete response (CR), 5 patients with partial response (PR)) as evidenced by a 48% overall disease control rate (i.e., SD + PR + CR). The results are impressive because the disease control response population includes patients with primary and secondary platinum drug resistance who have failed prior treatment with pegylated liposomal doxorubicin (Doxil®, Caelyx®, Myocet®), gemcitabine (Gemzar®), topotecan (Hycamtin®), etoposide (Eposin®, Etopophos®, Vepesid®), bevacizumab (Avastin®), and/or other various experimental agents. Approximately 79% of the patient population that experienced disease control with Voreloxin at a 48mg/m² dosage received between two to four prior lines of treatment. In addition, one patient who experienced a partial response to Voreloxin at the 48 mg/m² dosage had a tumor histology identified as clear cell ovarian cancer — an aggressive form of ovarian cancer that is generally resistant to traditional therapies. It appears that there are 11 clear cell ovarian cancer patients participating in the Voreloxin Phase II trial (i.e., 7 patients in the 48 mg/m² dosage arm, and 4 patients in the 60 mg/m² dosage arm); however, there are no specific results reported for these patients (other than the one partial responder) in the 2008 ASCO Annual Meeting abstract presentation data.

Due to the earlier success of Voreloxin prior to March 15th, the trial investigators enrolled 21 new patients into the Phase II trial for purposes of testing Voreloxin at a 60 mg/m² dosage. Because these newer patients only received two cycles of Voreloxin at the higher dosage to date, they were not evaluated officially for purposes of the 2008 ASCO Annual Meeting abstract presentation data. The grade 3/4 adverse effects of Voreloxin at both dosages are reported as relatively low, therefore, trial investigators incorporated a 75 mg/m² dosage escalation into the current Phase II trial. The investigators do not indicate how many patients (currently enrolled or newly recruited) will participate in the 75 mg/m² dosage arm. Currently, a total of 86 ovarian cancer patients are enrolled in the Voreloxin Phase II trial (65 patients in the 48 mg/m² dosage arm; 21 patients in the 60 mg/m² dosage arm).

[Sources: “A Phase 2 Trial of Voreloxin (Formerly SNS-595) in Women with Platinum-Resistant Epithelial Ovarian Cancer,” 2008 American Society of Clinical Oncology Annual Meeting Presentation, May 31, 2008 (Adobe Reader PDF Document). See also, “A phase II trial of SNS-595 in women with platinum resistant epithelial ovarian cancer,” W. P. McGuire et. al., J Clin Oncol 26: 2008 (May 20 suppl; abstr 5582) (2008 ASCO Annual Mtg. Abstract); “A Phase 2 Open-Label, Multicenter Study of SNS-595 Injection in Patients With Platinum-Resistant Ovarian Cancer, National Cancer Institute ID# NCT00408603 (sets forth original Voreloxin (SNS-595) Phase II clinical trial protocol).

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