Japan's Astellas Pharma has to fight antitrust claims related to its transplant drug Prograf. The drugmaker failed to persuade a U.S. judge to dismiss consumer allegations it petitioned the FDA about generic versions of Prograf simply to extend its market exclusivity, rather than out of concern for public health, Courthouse News Service reports.

The consumer lawsuits, consolidated in a Massachusetts federal court, claim Astellas filed a "sham" petition to stop generic Prograf, then proceeded to collect almost $1 billion in exclusive sales while the FDA considered its complaint. Astellas asked U.S. District Judge Rya Zobel to dismiss the cases, citing First Amendment protection for its petition, but Zobel didn't buy it.

"When petitioning conduct is a mere sham to cover what is actually nothing more than an attempt to interfere directly with the business relationship of a competitor, such conduct is not immune," Zobel wrote in denying Astellas' motion (as quoted by CNS). The antitrust allegations were "more than sufficient to withstand a motion to dismiss," she found.

Astellas faces similar claims in a class action filed by insurers in Massachusetts court.