Astellas Pharma has decided to end its legal action against regulators in the USA over generic versions of the Japanese drugmaker’s blockbuster Prograf.

The Tokyo-based firm’s North American affiliate has dismissed its lawsuit against the US Food and Drug Administration which was filed in August after the agency denied Astellas’ ‘Citizen Petition’ about generics of Prograf (tacrolimus), its immunosuppressive treatment used to help prevent rejection of a kidney or liver transplant. That appeal asked the FDA to protect transplant recipients, “a unique and vulnerable patient population, from substitute critical dose immunosuppressant drugs that have not demonstrated bioequivalence in rigorous clinical trials”.

The US District Court in Washington DC subsequently rejected Astellas’ appeal against the FDA's dismissal of the petition and Astellas said it was considering its next course of action. The lawsuit has therefore been dropped at a time when the take-up of Sandoz’ generic of tacrolimus has been quicker than expected and Astellas has reduced its full-year Prograf sales target by 8.4% to 184.30 billion yen.

Seattle Genetics deal expanded
Earlier this week, Astellas’Agensys unit expanded its collaboration with the USA’s Seattle Genetics. The latter will receive $12 million in exchange for exclusive rights to antibody-drug conjugate licenses against additional antigen targets and receive an option to co-develop another ADC.

Head of R&D at Agensys, Ava Jakobovits, said that combining the firm’s antibodies, “directed to novel cancer targets, with Seattle Genetics’ industry-leading ADC technology has already led to product candidates for different cancer indications”. They include ASG-5ME, an ADC for cancers including prostate, pancreatic and gastric, that will go into Phase I trials in 2010.

Under the terms of the amended deal, Seattle Genetics is eligible to receive up to $250 million in development and $100 million in sales milestones if all of the additional ADC programs are successful.