Will Corcept Therapeutics’s new patent for Korlym® help against Teva’s generic?
Zachary Silbersher
On April 17, 2018, a new patent issued to Corcept Therapeutics ($CORT) that covers Korlym®. The patent is U.S. Patent No. 9,943,526 pursuant to U.S. Patent Application No. 15/133,791. The ‘526 patent has already been added to the Orange Book. Korlym® was already protected by two patents listed in the Orange Book, and Corcept recently commenced a Hatch-Waxman litigation against Teva asserting these two patents. How effective is the new ‘526 patent at keeping Teva ($TEVA) at bay?
The ‘526 patent is directed to a method of treating Cushing’s syndrome, which involves administering seven daily doses of mifepristone for seven days, testing plasma mifepristone levels, and then adjusting the mifepristone doses depending on the results of the tested plasma mifepristone levels. In short, as discussed in our earlier post, this is another diagnostic patent. Indeed, it is very similar to one of the patents already listed in the Orange Book for Korlym®, namely, U.S. Patent No. 8,921,348, even though the ‘526 patent does not claim priority to the ‘348 patent. Even if Corcept can come forward with a tractable infringement argument, for the same reasons discussed in our earlier post, the ‘526 patent is subject to being invalidate for being directed to ineligible subject matter.
Our earlier post indicated that the ‘348 patent may not be infringed by Teva’s generic because the Korlym® label prescribes daily administration, whereas the ‘348 patent requires “seven or more daily doses of mifepristone . . . .” (That same language appears in the ‘526 patent, and thus potentially yields the same non-infringement argument for Teva for the ‘526 patent as well.) That language (“seven or more daily doses”) suggests that the patent requires administering seven doses in one day. That, in turn, suggests Teva’s generic will not infringe the patent because the label for Korlym® indicates once-daily administration, rather than seven times a day.
Yet, Corcept will likely argue that the patent should be construed to require seven total daily doses, which are administered over the course of seven days. There is arguably support for this construction in the patent’s specification. For instance, the Phase III trial described in Example III of the ‘348 patent indicates the drug was administered once-daily for seven days. Further, both the ‘348 and ’526 patents state: “Generally, treatment is initiated with six daily doses, with the blood levels tested on the day of the seventh daily dose in order to determine whether the dose used is providing a mifepristone blood level of at least . . . . .” Together, this evidence is not dispositive because Corcept will essentially have to argue that the phrase, “seven or more daily doses” has the same meaning as "one or more daily doses" or even just “daily doses” Yet, it is likely that Corcept will not be required to show that Teva’s generic must be administered seven times in one day to infringe the ‘348 patent. The same likely holds for the recently-issued ‘526 patent.
That opens up the question whether Teva has any other strong non-infringement arguments? The label for Korlym® does provide that initial mifepristone doses of 300 mg can be titrated up in 300 mg increments. (See Sec. 2.1). That is similar to what the ‘348 and ‘526 patents are presumably directed to. Yet, the label states, “[d]ecisions about dose increases should be based on a clinical assessment of tolerability and degree of improvement in Cushing’s syndrome manifestations.” The label does not specifically instruct testing plasma or serum levels of the patients, which is required by the ‘348 and ‘526 patents. Thus, this issue may form the focus of Corcept’s litigation against Teva.
Our earlier post discussed in detail three additional pending patent applications (the ‘465, ‘359 and ‘368,) which if successfully allowed, will present veritable obstacles to Teva’s generic. Corcept has other pending patent applications, in addition to those discussed in our earlier post. For instance, U.S. Patent Application No. 15/796,443 is currently pending. The patent claims priority to one of Korlym®’s patents already listed in the Orange Book, namely, U.S. Patent No. 9,829,495. The ‘443 patent application has yet to receive a Notice of Allowance. Given that the ‘443 patent application is subject to similar subject matter as the ‘495 patent, it is likely to face similar obstacles discussed in our earlier post to barring Teva’s generic competition. Similarly, U.S. Patent Application No. 15/627,414 is also currently pending, and has also yet to receive a Notice of Allowance. Corcept also has another patent that is scheduled to issue on May 1, 2018. This will be U.S. Patent No. 9,956,216 pursuant to U.S. Patent Application No. 15/621,013. It is part of a family of patents directed to heteroaryl ketone fused azadecalin compounds and methods of using the compounds as glucocorticoid receptor modulators, including for the treatment of Cushings syndrome. Parent patents for the ‘216 patent, including U.S. Patent 9,273,047, which issued in March 2016, have not been listed in the Orange Book for Korlym®.
Overall, even though Corcept’s recently listed ‘526 patent adds arguably minimal more weight to its arsenal, Corcept’s pending patent applications (the ‘465, ‘359 and ‘368 applications) should, when allowed, make it well-positioned against Teva’s generic.