Days after regaining the rights to its antibiotic ceftobiprole from partner Johnson & Johnson, Basilea has signed a potentially lucrative pact for its investigational late-stage antifungal with Astellas Pharma.

Under the terms of the deal, the Japanese drugmaker is making an upfront payment of 75 million Swiss francs (around $69.3 million) to get access to isavuconazole, which is in Phase III trials for the treatment of life-threatening invasive fungal infections. Basilea may also receive up to 478 million francs in development and sales milestones and will also be eligible for “significant double-digit tiered royalties”.

The Swiss drugmaker retains an option to co-promote the product in the USA, Canada, major European countries and China. It will also initially manage manufacturing of the drug.

Masafumi Nogimori, Astellas chief executive, noted that his firm already has experience in the development and marketing of the echinocandin antifungal agent Mycamine (micafungin) worldwide and “this partnership is an important step to further expand our business and to reinforce our franchise in infectious diseases."

Basilea chief executive Anthony Man said the pact “further validates the unique and highly competitive profile of isavuconazole”, which has been granted fast track designation by the US Food and Drug Administration, “and its potential as a best-in-class antifungal”. He added that “the financial contribution from this partnership allows us to further expand Basilea's commercial efforts in key markets as needed as well as advance our promising pipeline projects”.

The deal is a major boost for Basilea coming days after the European Medicines Agency’s Committee for Medicinal Products for Human Use turned down an application for the superbug drug ceftobiprole. The reliability of the results from the filing, made by J&J, was questioned and the rights have been returned to Basilea.

The Astellas deal has gone down very well with investors and at 9.50am (UK time), Basilea shares had shot up 10.4% to 77.95 francs.