In IPR2015-01537, Momenta petitioned for IPR of claims 1-15 of U.S. Patent No. 8,476,239 owned by Bristol-Myers Squibb (BMS) on grounds of obviousness over three references: Cohen, Shire, and Carpenter.  Petitioner also relied on expert testimony.  The claims recite formulations containing CTLA4Ig, which is a stabilized form of a negative regulator (checkpoint inhibitor) of the immune system useful in treating autoimmune disease and rheumatoid arthritis, for example.  The Patent Owner opposed institution by attacking the Petitioner’s position as failing to provide a reason to combine the cited references and as relying on impermissible hindsight in arriving at a formulation that satisfied all features recited in the claims (i.e., tonicity, pH, excipient concentration, excipient:therapeutic mass ratio, volume, and stability).