Abstract: Provided are methods and compositions for identifying binding polypeptides (e.g., antibodies or antigen binding fragments thereof) that specifically binds to a cell-surface antigen. The methods of the invention generally comprise contacting a variegated nucleic acid-display library of binding polypeptides with a cell-surface antigen displayed on the exterior surface of a cell; and isolating from the library at least one library member that specifically binds to the cell-surface antigen on the exterior surface of the cell. Also provided are novel nucleic acid display libraries (e.g., DNA display libraries) useful in the methods of the invention.

Abstract: Provided are ROR1 binding molecules, including anti-ROR1 antibodies, including antibody fragments such as variable heavy chain (VH) regions, single-chain fragments, and chimeric receptors including the antibodies, such as chimeric antigen receptors (CARs). In some embodiments, the antibodies specifically bind to ROR1. Among the antibodies are human antibodies, including those that compete for binding to ROR1 with reference antibodies, such as a non-human reference antibody. Also provided are genetically engineered cells expressing the chimeric receptors, and uses of the binding molecules and cells adoptive cell therapy.

Abstract: Provided are CD19 binding molecules, including anti-CD19 antibodies, including antibody fragments such as single-chain fragments, and chimeric receptors including the antibodies, such as chimeric antigen receptors (CARs). Among the antibodies are human antibodies, including those that compete for binding to CD19 with reference antibodies, such as murine antibodies. In some embodiments, the antibodies display similar functional properties to the reference antibodies, such as comparable binding affinities and/or competitive inhibition properties. Also provided are genetically engineered cells expressing the chimeric receptors, and uses of the binding molecules and cells adoptive cell therapy.

Abstract: The invention provides methods and compositions for identifying binding polypeptides (e.g., antibodies or antigen binding fragments thereof) that specifically binds to a cell-surface antigen. The methods of the invention generally comprise contacting a variegated nucleic acid-display library of binding polypeptides with a cell-surface antigen displayed on the exterior surface of a cell; and isolating from the library at least one library member that specifically binds to the cell-surface antigen on the exterior surface of the cell.