Over the last two weeks, Pfizer, Inc. (“Pfizer”) has filed petitions for inter partes review (“IPR”) of three additional patents related to Biogen and Genentech’s Rituxan® (rituximab) at the Patent Trial and Appeal Board (“PTAB”).  The proceedings are: IPR2017-01166, filed on April 21, 2017, regarding U.S. Patent No. 8,329,172 (“the ’172 patent”); IPR2017-1167, filed on April 27, 2017, regarding U.S. Patent No. 8,557,244 (“the ’244 patent”); and IPR 2017-1168, filed on April 28, 2017, regarding U.S. Patent No. 8,821,873 (“the ’873 patent”). Biogen is identified as the Patent Owner and Pfizer, Inc. is the sole real party-in-interest identified for Petitioner in all three petitions.

Rituximab is an anti-CD20 monoclonal antibody approved for the treatment of non-Hodgkin’s lymphoma, chronic lyphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangitis, and microscopic polyangitis.  Pfizer announced in January 2017 that its proposed biosimilar rituximab (PF 05280586) is in Phase 3 development.

The sole claim of the ’172 patent is directed to a method of treating low-grade B-cell non-Hodgkin’s lymphoma (“NHL”) by administering a well-known chemotherapy regimen of cyclophosphamide, vincristine, and prednisone (“CVP”), followed by rituximab maintenance therapy administered in four weekly doses of 375 mg/m² every six months for two years.  The ’244 patent has two claims.  Claim 1 of the ’244 patent is directed to a method of treating a patient with diffuse large cell lymphoma (a subset of NHL) by administering a combination of an unlabeled chimeric anti-CD20 antibody and chemotherapy, the chemotherapy consisting of cyclophosphamide, hydroxydaunorubicin/doxorubicin, vincristine, and prednisone/prednisolone (“CHOP”).  The treatment claimed in the ’244 patent is specific to a patient who is greater than 60 years old, has bulky disease, and has a tumor greater than 10 cm in diameter. Claim 2 of the ’244 patent further limits the chimeric anti-CD20 antibody to rituximab.  The ’873 patent has five claims that are generally directed to methods of treating a patient with diffuse large cell lymphoma by administering a combination of an anti-CD20 antibody and CHOP chemotherapy, whereby the antibody is administered to the patient in combination with a stem cell transplantation regimen. The treatment claimed in the ’873 patent is also specific to a patient who is greater than 60 years old, and claim 3 of the ’873 specifically limits the anti-CD20 antibody to rituximab.

Earlier this year, Pfizer filed a petition with the PTAB for IPR of U.S. Patent No. 7,820,161 (“the ’161 patent”), which is also related to Biogen and Genentech’s Rituxan® (rituximab), as we reported in this post.  Prior to the filing of that petition, in February 2017, the PTAB instituted an IPR for certain claims of the ’161 patent on a petition filed by Celltrion (as we reported here), and Pfizer has requested that its petition be joined with that proceeding.  Celltrion currently has petitions pending for review of three other patents related to rituximab as reported here, and the PTAB denied Celltrion’s petition related to U.S. Patent No. 7,976,838 as reported here.  Boehringer Ingelheim and Celltrion had previously filed petitions at the PTAB for patents related to this same product that were voluntarily dismissed in 2015.

A complete list of IPRs related to rituximab and other proposed biosimilars can be found in RFEM’s IPR Dashboard.  We will continue to provide updates as these cases progress.