Sunesis Pharmaceuticals, Inc. announced that the US Patent and Trademark Office (USPTO) issued US Patent No. 7,989,468 claiming methods of use for the company's lead drug candidate, vosaroxin, at clinically relevant dose ranges and schedules, for the treatment of leukaemia. The '468 patent, which is based on an application filed on March 14, 2005, is subject to a patent term adjustment under title 35, section 154 (b) of US Code, extending its coverage through 2026. Corresponding patent applications are pending in major markets throughout the world including Europe, Japan, Australia and Canada. Sunesis is currently enrolling a phase III, multinational, randomized, double-blind, placebo-controlled, pivotal clinical trial of vosaroxin in combination with cytarabine in first relapsed or refractory Acute Myeloid Leukaemia (AML), the Valor trial.

“The '468 patent adds another important facet to our global intellectual property estate for vosaroxin, providing significant coverage for uses of vosaroxin in the treatment of leukaemia including the dose and schedule under evaluation in the pivotal, phase III Valor trial,” said Dan Swisher, chief executive officer of Sunesis. “Sunesis continues to pursue an intellectual property strategy that we believe will provide additional exclusive coverage in the vosaroxin patent estate. To supplement our granted patents, we have filed patent applications in territories around the world with claims covering additional vosaroxin formulations, combination uses, dosing, manufacturing processes and composition of matter claims, which may provide patent terms to 2030 when granted.”

Valor is a phase III, randomized, double-blind, placebo-controlled, pivotal trial in patients with first relapsed or refractory AML. The trial is expected to enroll 450 evaluable patients at approximately 100 leading sites in the US, Canada, Europe, Australia and New Zealand. The Valor trial is currently open for enrollment and patients will be randomized one to one to receive either vosaroxin on days one and four in combination with cytarabine daily for five days, or placebo in combination with cytarabine. Additionally, the Valor trial employs an innovative, adaptive trial design that allows for a one-time sample size adjustment by the DSMB at the interim analysis to maintain adequate power across a broad range of clinically meaningful and statistically significant survival outcomes. The trial's primary endpoint is overall survival.

Vosaroxin is a first-in-class anticancer quinolone derivative, or AQD, a class of compounds that has not been used previously for the treatment of cancer. Vosaroxin both intercalates DNA and inhibits topoisomerase II, resulting in replication-dependent, site-selective DNA damage, G2 arrest and apoptosis.

AML is a rapidly progressing cancer of the blood characterized by the uncontrolled proliferation of immature blast cells in the bone marrow. The American Cancer Society estimated that 12,330 cases of AML were diagnosed and approximately 9,000 deaths from AML occurred in the US in 2010. Additionally, it is estimated that prevalence of AML is approximately 25,000 in the US AML is generally a disease of older adults, and the median age of a patient diagnosed with AML is about 67 years. AML patients with relapsed or refractory disease and newly diagnosed AML patients over 60 years of age with poor prognostic risk factors typically die within one year, resulting in an acute need for new treatment options for these patients.

Sunesis is a biopharmaceutical company focused on the development and commercialization of new oncology therapeutics for the treatment of solid and haematologic cancers.