BioWorld International Correspondent

PARIS - Little more than two weeks after signing an exclusive licensing agreement with BioAlliance Pharma SA granting the French company European commercialization rights to pafuramidine maleate, Immtech Pharmaceuticals Inc. announced that it was suspending development of the drug after "abnormal laboratory values were found in volunteers following treatment with pafuramidine."

Immtech Pharmaceuticals, of New York, said in a statement that it had "discussed the preliminary findings with the U.S. Food and Drug Administration, and as a precautionary measure, the pafuramidine program has been placed on clinical hold. The clinical hold may be released after FDA has received satisfactory data regarding the safety of pafuramidine."

Immtech is developing an orally administered formulation of pafuramidine for the treatment of pneumocystis pneumonia (PCP) in AIDS patients and human African trypanosomiasis, also known as African sleeping sickness, and the drug is currently in Phase III clinical trials in both those indications in the U.S., where pafuramidine has been granted orphan drug designation for the treatment of PCP.

The trial that now has been suspended was an additional safety study being conducted in South Africa to "collect additional safety data regarding pafuramidine to support the indications of pneumocystis pneumonia and African sleeping sickness," Immtech explained. Following the adverse events, "the subjects are undergoing close monitoring for any changes in the status of their liver function," the company said, albeit adding: "No subject has required any treatment or hospitalization for the abnormalities."

According to Carol Olson, senior vice president of pharmaceutical development and chief medical officer of Immtech, "this evaluation will continue until patients stabilize or return to baseline status. At that time, Immtech and the independent experts in liver toxicity will prepare a summary of the available safety data and recommendations for presentation to the FDA."

Paris-based BioAlliance Pharma responded to the Immtech statement by saying that it would "decide whether or not to go ahead with the product after reviewing the available safety data and recommendations." The company's financial exposure is limited to the $3 million it paid up front on signing the agreement with Immtech, which also gave BioAlliance an option to market pafuramidine in Europe for the prevention and treatment of malaria in travelers.

Immtech stood to receive a further $13 million in milestone payments if pafuramidine obtained regulatory approval in Europe, as well as "significant" royalties on sales and additional milestones linked to the value of sales. Furthermore, if BioAlliance decided to exercise its option to commercialize pafuramidine for malaria prophylaxis, the French company would start sharing the clinical development costs of a Phase III trial, while marketing approval in malaria would trigger the payment of additional regulatory and sales-related milestones to Immtech, plus royalties on sales.

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