The Patent Trial and Appeal Board (“the Board”) has decided not to institute inter partes review (“IPR”) on two patents owned by Biogen and Genentech. Pfizer, Inc. (“Pfizer”) filed two petitions asserting that the patents, U.S. Patent Nos. 8,206,711 (“the ’711 patent”) and 7,682,612 (“the ’612 patent”), were invalid as obvious in view of prior art. Both of these patents relate to Rituxan® (rituximab) and its use in the treatment of chronic lymphocytic leukemia (“CLL”).

Last month, the Board denied Pfizer’s IPR petition for the ’711 patent, finding that all of the claims were not obvious over the cited prior art. Pfizer, Inc. v. Biogen, Inc., IPR2017-02127 (PTAB Apr. 19, 2018) (Paper 10). The Board held that the cited prior art failed “to provide guidance concerning clinical endpoints, treatment parameters, or other information relating to how one would treat CLL with rituximab, or why one would reasonably expect such treatment to be successful.” Id.at 23.

This past week, the Board denied Pfizer’s other petition for the ’612 patent, again finding that the claims were not obvious over the prior art. Pfizer, Inc. v. Biogen, Inc., IPR2017-02126 (PTAB Apr. 30, 2018) (Paper 10). Pfizer argued that the prior art “would have provided an ordinarily skilled artisan with a reasonable expectation of success for methods of using rituximab to treat CLL patients at the claimed doses.” Id.at 11. However, the Board disagreed that the prior art demonstrated that “an ordinarily skilled artisan would have had a reasonable expectation of success in using any dosage of rituximab to treat CLL.” Id. at 10. Rather, the prior art suggested “a rationale for exploring the possibility of treating CLL with rituximab,” but such suggestion amounted “to no more than an invitation to experiment.” Id. at 10.

This is not the first challenge to these two Rituxan® patents. Celltrion, Inc. previously filed three IPR petitions challenging both patents, all of which were denied by the Board. See Celltrion, Inc. v. Biogen, Inc., IPR2017- 01227 (PTAB Oct. 23, 2017) (Paper 10); Celltrion, Inc. v. Biogen, Inc., IPR2017-01230 (PTAB Oct. 12, 2017) (Paper 12); Celltrion, Inc. v. Biogen, Inc., IPR2017-01229 (PTAB Oct. 23, 2017) (Paper 10).