ASA404 failed as first-line treatment, and interim data on its potential as a second-line therapy is due later this year.

Antisoma’s share price plunged 70% on the news that lead anticancer drug, ASA404, flopped in its first Phase III trial due to lack of efficacy. The ATTRACT-1 trial, carried out by Novartis, Antisoma’s global licensee for ASA404, was evaluating the small molecule tumor vascular disrupting agent as a first-line therapy in patients with non-small-cell lung cancer (NSCLC).

An interim analysis of data from ATTRACT-1 concluded that continuing the study would be futile, as ASA404 showed “little or no prospect of demonstrating a survival benefit,” the company admits.

Antisoma outlicensed global ASA404 rights to Novartis in 2007. The U.K.-based company has already earned at least $100 million from the potentially $890 million deal: $75 million up front payment and another $25 million when ASA404 started in its first Phase III lung cancer trial. Novartis’ share price wobbled a bit on the announcement of the ATTRACT-1 trial failure, with a drop just shy of 1%.

Novartis is carrying out a second Phase III trial, ATTRACT-2, evaluating ASA404 as a second-line treatment in NSCLC patients. This trial is scheduled for completion in 2011, with an interim analysis due this year.

Back in February 2009, Antisoma said that Novartis had decided that the next indication for ASA404 development would be the treatment of Her2-negative metastatic breast cancer. Antisoma had previously suggested that the breast cancer program would include a Phase Ib/II trial starting this year.

Antisoma has also carried out Phase II trials with ASA404 in combination with standard chemotherapy in prostate and ovarian cancers. The Phase II ovarian cancer trial also crashed in 2007, and further development of ASA404 for this indication was subsequently dropped.

“We are disappointed by the outcome of the ATTRACT-1 study, especially given the very encouraging Phase II data reported in the same setting,” remarks Antisoma CEO, Glyn Edwards. “We are now focused on delivering Phase III results for our other late-stage product AS1413.”

AS1413 is a DNA intercalator currently in Phase III development against secondary acute myeloid leukaemia (AML). The Antisoma pipeline also includes the nucleolin-binding aptamer AS1411. In February the firm started a Phase IIb trial with the candidate in patients with AML.

Antisoma’s other clinical-stage candidate, AS1409, is a fusion protein combining IL-12 with the tumor-targeting antibody BC1. A Phase I trial with AS1409 in patients with malignant melanoma and renal cell carcinoma has been completed.

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