Korlym® faces another potential generic from Sun Pharma

Zachary Silbersher

Another generic has filed an ANDA with the FDA for a license to distribute a generic version of Korlym®.  Teva is no longer the only company seeking to sell generic Korlym®, which therefore increases the likelihood that Corcept Therapeutics ($CORT) will face a generic competitor for its main drug at some point in the future.

Corcept filed a Hatch-Waxman complaint against Sun Pharma on July 22, 2019.  The complaint refers to a Paragraph IV certification sent by Sun Pharma on or about June 7, 2019, which prompted the suit by Corcept.  Notably, Corcept has only asserted three patents against Sun Pharma:  the ‘348 patent, the ‘214 patent and the ‘495 patent.   

There are a few things to note about Corcept’s newest lawsuit against a proposed generic for Korlym®.  For one thing, the company only asserted three patents.  When Teva first filed its ANDA in January 2018, the Orange Book listed only two patents covering Korlym®, including the ‘348 patent and the ‘495 patent.  Since then, Corcept has fast-tracked issuance of several more patents.  The Orange Book currently lists ten patents covering Korlym®.

Corcept’s original complaint against Teva asserted only the ‘348 and ‘495 patents, the two patents listed in the Orange Book at the time.  After acquiring more patents, Corcept amended its complaint against Teva to add the ‘526 patent.  More recently, in May 2019, Corcept commenced another suit against Teva that asserted three more patents: the ‘214 patent, the ‘242 patent and the ‘243 patent.  Thus, Corcept is currently asserting six patents against Teva’s proposed generic for Korlym®. 

By contrast, in its suit against Sun Pharma, Corcept has only asserted three patents.  Corcept has asserted the ‘348 and ‘495 patents as well as the ‘214 patent.   As we previously discussed, proving infringement of ‘348 or ‘495 patents will be difficult for Corcept because these inventions are not necessarily disclosed in Korlym®’s label.  For this reason, Teva has claimed that Corcept’s assertion of these patents is patent misuse.

Another quirk within Corcept’s recent filing against Sun Pharma is its choice to once again assert the ‘348 patent.  The validity of that patent has been challenged in a petition for inter partes review (IPR).  The IPR was instituted in February 2019, which is effectively a holding by the Patent Office that the ‘348 patent may likely be invalidated.   

The patent that really matters in this fight, against both Sun Pharma as well as Teva, remains the ‘214 patent.  Among those asserted against the generics, the’214 patent is the only one that is likely to be infringed given that the subject matter of the patent is even arguably covered by Korlym®’s label.  The Korlym® label includes a warning for patients taking Korlym® with strong CYP3A inhibitors, such as ketoconazole, which appears to be generally covered by the ‘214 patent.

Indeed, this is evident by the fact that Teva previously filed an IPR against the ’214 patent in May 2019.  By filing an IPR against the ‘214 patent, but not any other asserted patents, Teva may be tacitly acknowledging that it faces some risk on potentially infringing the ‘214 patent.

Overall, it is no surprise that Corcept asserted the ‘214 patent against Sun Pharma, given that that is likely its strongest patent from an infringement perspective.  It is less clear why Corcept chose to reassert the ‘348 patent, which is subject to a pending IPR.  It is also not entirely clear why Corcept did not also assert the ’242, ‘243 or ‘526 patents against Sun Pharma, despite asserting them against Teva.  There may be technical reasons, namely, that non-public information disclosed within Sun Pharma’s ANDA makes it clear these patents are not infringed.  That, or Corcept may have taken at least some of Teva’s allegations of patent misuse seriously, and chose not to double-down on them. 

Overall, another generic contender increases the likelihood of generic competition to Korlym® sometime soon.  Practically, however, Sun Pharmaceuticals appearance may be a small boon for Corcept.  Teva’s case was delayed by nearly a year while Teva pursued a motion to dismiss Corcept’s complaint.  That means, the case is not as far along as it otherwise might have been.  If there is any chance that Teva’s case is slowed down for Sun Pharma’s case to catch up—which remains to be seen—that delay could be profitable for Corcept.

Also, it bears emphasis that Corcept only has to prevail on a single patent to be technically entitled to an injunction against generics.  Right now, the ‘214 patent stands to be the best contender for that.  The patent does not expire until 2037, thus in the best case scenario, prevailing on the ‘214 patent alone could guarantee Korlym® free of generic competition for nearly infinity. 

For this reason, Teva’s pending IPR against the ‘214 patent could be a real game-changer.  The IPR is scheduled to receive an institution decision by late November 2019.  This will be a key date to watch for investors.