Amgen Inc. filed a lawsuit against the U.S. Food and Drug Administration alleging that the regulator unlawfully denied pediatric exclusivity to one of its treatments.
Sensipar is meant to treat secondary hyperparathyroidism, which can lead to bone fractures and deformities. The drug is already approved for adults and was prescribed off label to the pediatric population, prompting the FDA to ask the company to investigate it in that population.
The U.S. FDA is required to grant six months of additional market exclusivity and patent protection to drugs for which pediatric studies have been requested.
However, the regulator denied exclusivity after the company failed to enroll the required number of patients in the study.
Amgen argued in the suit, filed with the U.S. District Court for the District of Columbia, that it was unable to find enough candidates due to lower patient population and that its study data be considered "fair" given the circumstances.
The plaintiff further said the studies are not required to demonstrate that the drugs are safe or effective in children to warrant pediatric exclusivity.
The company is seeking to have the regulator's decision overturned.
Sensipar generated $1.58 billion in global sales during 2016, and a pediatric exclusivity would help Amgen fend off generic competition.
A key patent covering Sensipar is due to expire in March 2018.
Amgen won a court ruling against Teva Pharmaceutical Industries Ltd. in 2011, blocking its attempt to launch a generic version of Sensipar. The company has filed separate lawsuits against 13 companies, including Mylan NV and Aurobindo Pharma Ltd., for infringing on a Sensipar patent.