On October 3, 2017, Pfizer, Inc. (“Pfizer”) filed a petition for inter partes review (“IPR”) against U.S. Patent No. 7,846,441 (“the ʼ441 patent”), assigned to Genentech, Inc. (“Genentech”), entitled “Treatment with anti-ErbB2 antibodies.”  The ʼ441 patent is related to Genentech’s Herceptin® (trastuzumab) product.  Last November, Pfizer announced positive results in a pivotal safety and efficacy study comparing Herceptin® to Pfizer’s potential biosimilar to Herceptin®.  Pfizer has not yet announced the filing of an application for its potential biosimilar to the FDA.

As we previously reported, two other IPR petitions have been previously filed against the ʼ441 patent.  IPR2017-00731 was filed by Hospira Inc., a Pfizer subsidiary, and institution was denied on July 27, 2017.  IPR2017-01121 was filed by Celltrion, Inc. on March 21, 2017, and an institution decision has not yet been entered.  However, Pfizer moved to join the Celltrion IPR on September 7, 2017, by filing a petition challenging the same claims on the same grounds.  That proceeding is IPR2017-02063.

In its newly-filed IPR, Pfizer asserts that the combination claimed in the ʼ441 patent was disclosed in an article in the LA Times more than one year before the priority date of the ʼ441 patent.  According to Pfizer, the article “A Lottery of Life, Death – and Hope” disclosed that “HER2-overexpressing breast cancer patients were being treated with the same combination therapy” claimed in the ʼ441 patent.  Pfizer claims that the LA Times article was newly discovered and was not identified by the examiner during prosecution.

Pfizer’s petition also includes a second ground adding a reference to a combination previously advanced in IPR2017-00731.  According to Pfizer, it reasonably believed that the limitation “in the absence of an anthracycline derivative” was sufficiently disclosed in the two references combined in its prior petition based on statements made by the patent owner and the examiner during prosecution. Thus, Pfizer asserts that it “could not have anticipated” Genentech seeking a construction of that term that would require “‘avoidance’ of anthracyclines, rather than simply their ‘absence’ in a treatment regimen.”  Pfizer claims it was “this unanticipated shift that led the Board” to deny institution. Pfizer argues the new reference supplies this limitation because it excluded patients from a clinical trial if they were previously treated with anthracycline.

Herceptin® is a monoclonal antibody that interferes with human epidermal growth factor receptor (HER2)/neu.  The produce is indicated for the treatment of patients with metastatic breast cancer whose tumors overexpress the HER2 protein and who have received one or more chemotherapy regimens for their metastatic disease.

The newly-filed proceeding is IPR2018-00016. Pfizer is identified as the only real party-in-interest.

We will continue to keep you updated on future developments.