BioWorld International Correspondent

LONDON - Protherics plc bought out the rights to the dioxin-poisoning treatment Digitalis Antidot, or Digidot, from F. Hoffmann-La Roche Ltd., as a route to building an exclusive European franchise around DigiFab, its own treatment for dioxin overdose.

DigiFab currently is available on a named-patient basis in Europe, with London-based Protherics expecting approval in the first quarter. The company said it will replace Digidot, approved in France, Germany and Switzerland, with DigiFab.

The amount Protherics paid, in cash, to acquire the rights was not disclosed, but the company said it now is working with Roche to ensure a smooth transition between the products.

Digidot and DigiFab are interchangeable, but Protherics CEO Andrew Heath said that with sales of €2 million to €3 million (US$3.9 million) annually in the three European countries in which it is registered, Digidot is too small a market for Roche to maintain its interest.

Eugene Tierney, business director at Roche, said the Basel, Switzerland-based company has been looking for someone to take over its digitalis intoxication business to ensure a treatment remains on the market.

Also identical in effect to Digidot and DigiFab is GlaxoSmithKline plc's product Digibind. Protherics has succeeded in taking an 80 percent share of the U.S. market for digoxin antidotes against Digibind by pricing it 20 percent less. Heath said Protherics also would like to buy out Glaxo's Digibind rights.

DigiFab, consisting of polyclonal ovine antibody fragments, is approved by the FDA, and has been submitted to UK regulators. Protherics plans to apply for marketing approval elsewhere in Europe, following UK approval. It will be marketed by Protherics in Germany and the Nordic countries, and by licensee Beacon Pharmaceuticals elsewhere in Europe.

Digoxin is used to treat heart failure, but has a very low therapeutic index, leading to an estimated 7,500 cases of digoxin poisoning in the U.S. each year.

Protherics is in need of positive developments, having reported setbacks to its two main development-stage products earlier in November.

On Nov. 3, the company announced that, following consultation with the FDA and the European regulator EMEA, its partner AstraZeneca plc would have to conduct an additional Phase IIb study of CytoFab, for the treatment of septic shock.

At the time that AstraZeneca and Protherics concluded the licensing deal for CytoFab in December, the partners said that a single global Phase III, due to start in 2007, would be sufficient to file for approval. The new 480-patient Phase IIb study will start in the second half of 2007, and take 21 months to complete, significantly delaying the start of Phase III.

Announcing the delay, Heath said the companies planned to discuss how it would affect the timing of the £171 million (US$331.1 million) in milestone payments that Protherics is due to receive.

The announcement pushed Protherics' shares down 13 percent to 70 pence. The market had scarcely digested that news when Protherics reported Nov. 7 that it had withdrawn the U.S. biologics license application for Voraxaze, a treatment for accidental overdoses of the chemotherapeutic methotrexate, after the FDA requested more manufacturing data.

Protherics said it expected to resubmit in 2007, but that the delay would push the U.S. launch back from the second half of 2007 to the second half of 2008. The shares fell to 65 pence on the news.

The company's stock (LSE:PTI) rose half a pence Monday to close at 70.5 pence.