USPTO published patent application US20260090529A1 for transgenic non-human animals producing modified heavy chain-only antibodies. The application claims animals genetically modified to produce HCAbs where the native amino acid at position one of FR4 is substituted with a different residue capable of disrupting a surface-exposed hydrophobic patch. The application (No. 19393163) was filed November 18, 2025, and published April 2, 2026, covering CPC classifications spanning A01K (transgenic animals) and C07K (peptides/proteins including antibody frameworks C07K 2317/21 through C07K 2317/569).

This patent application does not impose compliance obligations on regulated entities. Biotechnology and pharmaceutical companies developing antibody therapeutics should monitor this application to assess potential licensing implications or freedom-to-operate considerations for similar HCAb engineering approaches. Researchers and developers working with heavy chain-only antibody platforms should review the specific FR4 modifications claimed to understand the scope of protected modifications.