Last month, the PTAB issued decisions on two petitions, IPR2017-02063 and IPR2018-00016, filed by Pfizer against one of Genentech’s Herceptin® (trastuzumab) patents, U.S. Patent No. 7,846,441 (“the ‘441 patent”). The ‘441 patent has claims directed to methods of treating a malignant progressing tumor or cancer characterized by overexpression of ERBB2 receptor. IPR2017-02063 and IPR2018-00016 were the second and third petitions, respectively, filed by Pfizer challenging the ‘441 patent (as we reported here, the first petition, IPR2017-00731, was instituted on October 26, 2017). The board granted institution of the second petition because it is substantively identical to IPR2017-01121 filed by Celltrion, which was instituted on October 4, 2017. The board also granted Pfizer’s Motion for Joinder seeking to join the proceeding to IPR2017-01121. The board denied institution of the third petition because, unlike the second petition, there was no existing, instituted review, and Pfizer knew or should have known of the prior art raised in the third petition at the time the first two petitions were filed. Furthermore, at the time of filing of the third petition, Pfizer had already received Genentech’s preliminary response and the institution decision on the first petition.