Antisoma and its worldwide licensee Novartis have bowed to poor Phase III data and decided to ditch further development of the tumor-vascular disrupting agent ASA404 (vadimezan). The Attract-2 study in patients with advanced non-small-cell lung cancer (NSCLC) was stopped early on the recommendation of the independent data monitoring committee, which said interim data showed that combining the drug with chemotherapy was unlikely to prolong overall survival. The trial was evaluating ASA404 as second-line therapy.
The disappointing Attract-2 data has come as no surprise, Antisoma admits. In March the partners confirmed that the Phase III Attract-I trial had failed to show any benefits of combining ASA404 with carboplatin and paclitaxel as first-line treatment for advanced-stage NSCLC of squamous or nonsquamous histology.
As a result of discontinuing ASA404 development Novartis will incur an intangible asset impairment charge of $120 million in the fourth quarter of 2010. The firm had negotiated worldwide development rights to ASA404 from Antisoma back in 2007.
Antisoma will now have to pin its near-term hopes on the DNA intercalator AS413, which is currently in Phase III development for the treatment of secondary acute myeloid leukemia (AML). The pivotal Accede study is comparing therapy using AS1413 plus cytarabine, with standard induction chemotherapy of daunorubicin plus cytarabine. Enrollment of over 420 patients was completed in September 2010, and data is due to be reported during the first half of 2011. Antisoma says if this data is positive it plans to file for marketing authorization.
AS1413 is a topoisomerase II inhibitor, but the firm says that in contrast with classical TopoII inhibitors, AS1413 evades PgP and related transporters responsible for multidrug resistance. Earlier this week Antisoma received a grant of $244,000 under the U.S. Government’s Qualifying Therapeutic Discovery Project, to support the ongoing development of AS1413.
Antisoma’s clinical aptamer candidate, AS1411, is currently in Phase II evaluation in combination wtih high-dose cytarabine as a treatment for relapsed and refractory AML.