The U.S. Patent and Trademark Office (USPTO) revoked its patent examination guidelines that allowed broad antibody claims once an antigen was known after the Federal Circuit held in Amgen v. Sanofi (Fed. Cir. 2017) that the guidelines were inconsistent with the written description requirement of US patent law. The USPTO is preparing new examination guidelines that are likely to significantly increase the amount of data needed for allowance claims that are not limited to specific CDR sequences. We are monitoring legal developments in this technology area and welcome the opportunity to keep you updated.