U.S. Pat. No. 6,331,415, commonly referred to as “Cabilly II,” has been called one of the most-litigated patents of all time, having been challenged multiple times in both the district court and at the U.S. Patent and Trademark Office (“PTO”). On May 10, 2017, the last challenge standing against it was laid to rest, when petitioner Merck settled with the patent owners, City of Hope National Medical Center and Genentech (hereafter, collectively “Genentech”).

Cabilly II traces its history back to work done at City of Hope by inventor Shmuel Cabilly in the early 1980’s. A continuation of U.S. Pat. No. 4,816,567 (“Cabilly I”), Cabilly II was filed in 1988 and claims a priority date of April 8, 1983. However, due to a seven year interference proceeding, Cabilly II did not issue until 2001, delaying the start of its pre-GATT 17-year patent term. Cabilly II concerns antibody technology, specifically claiming a method of producing immunoglobulin molecules, or antibodies, using recombinant techniques. This technology, licensed to more than 70 biotech companies, has been instrumental in the creation of some of the first FDA-approved monoclonal antibodies (or “mAbs”), including the first two mAbs approved to treat cancer in the United States – rituximab and trastuzumab (marketed by Genentech under the trademarks Rituxan® and Herceptin®, respectively).

In addition to being at the heart of the 2007 landmark Supreme Court case that eased restrictions on licensees bringing declaratory judgment actions (MedImmune, Inc. v. Genentech, Inc.), Cabilly II has been the subject of several district court litigations (all of which have been dismissed or terminated), and has also survived two third party reexaminations at the PTO. Additionally, even after Cabilly II’s claims were upheld in the reexamination proceedings in 2009, it faced six separate IPR proceedings, brought by four different petitioners – Merck, Mylan, Genzyme, and co-petitioners Sanofi-Aventis and Regeneron (collectively referred to here as “Sanofi”).

Sanofi, the first to file an IPR against the Cabilly II patent, challenged the patent on both obviousness and anticipation grounds in July 2015 (IPR2015-01624). A few months later, Genzyme filed two petitions. Both Genzyme petitions challenged Cabilly II on obviousness and anticipation grounds, but one asserted the same prior art as Sanofi (IPR2016-00460), while the other relied on different prior art (IPR2016-00383). The PTO subsequently instituted Sanofi’s IPR in February 2016 solely on obviousness grounds, rejecting Sanofi’s anticipation arguments. After institution, following a motion for joinder, Genzyme’s parallel petition was consolidated with Sanofi’s in June 2016. However, the PTO denied institution of Genzyme’s second petition, finding the new prior art combinations unpersuasive. A few months later, all parties jointly requested termination of the consolidated IPR, notifying the PTO that they had entered into a settlement agreement that would end their disputes before the PTO and in their parallel district court litigations.

Meanwhile, Mylan filed a petition challenging Cabilly II in March 2016 (IPR2016-00710) on the same grounds that were instituted in Sanofi’s IPR, concurrently filing a motion for joinder. Both Sanofi and Genentech opposed the joinder, and by the time the PTO issued its institution decision ruling on the motion, Sanofi’s IPR had already been terminated. Mylan’s IPR was then instituted in September 2016.

Finally, Merck entered the fray, first filing a petition challenging Cabilly II on a different set of obviousness grounds (IPR2016-01373). Then, after Mylan’s IPR was instituted, Merck filed a second petition (IPR2017-00047) relying on the same grounds that resulted in institution for Sanofi, Genzyme, and Mylan, and requested joinder to Mylan’s IPR. The PTO denied institution of Merck’s first petition, finding that the art had already been considered by the PTO during Cabilly II’s reexamination. However, the PTO instituted the second petition and joined it with Mylan’s.

Three months later, and just a few days before the Petitioners’ reply brief was due, Mylan and Genentech entered into a settlement agreement. Mylan requested that it be removed from the IPR, leaving Merck as the sole remaining challenger. Although Merck filed its reply brief and proceeded with the case, a settlement agreement was ultimately negotiated and reported to the PTO on May 4, 2017. In addition to settling the IPR, Genentech and Merck’s agreement also settled their pending litigation of U.S. Pat. No. 7,923,221, a continuation patent of Cabilly II.

Thus, after many years of litigation and numerous settlements, the saga of Cabilly II has ended, just a little over a year and a half until its expiration in December, 2018.