Aspects of the disclosure relate to compositions of enzyme-binding polypeptides (EBPs) that modify the substrate specificity of an enzyme and a method for identifying an EBP that modifies substrate specificity of an enzyme binding at least one substrate, the method comprising: contacting the enzyme with a polypeptide library comprising a plurality of EBPs that bind different epitopes of the enzyme; identifying EBPs that bind to the enzyme to form an EBP-enzyme complex; assaying for the activity level and substrate specificity of the EBP-enzyme complex; and identifying EBPs that modify the substrate specificity of the enzyme by identifying EBPs that, when in an EBP-enzyme complex, have a different substrate specificity than un-complexed EBP; wherein the catalytic rate constant of the EBP-enzyme complex is ≥50% of the un-complexed enzyme for at least one substrate and/or wherein the EBP-enzyme complex retains binding to a substrate.

A trifunctional molecule comprising a target-specific ligand, a ligand that binds a protein associated with the TCR complex and a T cell receptor signaling domain polypeptide is provided. Engineering T cells with this novel receptor engenders antigen specific activation of numerous T cell functions, including cytokine production, degranulation and cytolysis.

The present disclosure relates to recombinant binding proteins comprising a designed ankyrin repeat domain with binding specificity for 4-1 BB (CD 137). In addition, the disclosure relates to nucleic acids encoding such binding proteins, pharmaceutical compositions comprising such binding proteins or nucleic acids, and the use of such binding proteins, nucleic acids or pharmaceutical compositions in methods for activating 4-1 BB in cells expressing 4-1 BB, e.g., tumor-localized T-lymphocytes, and for treating or diagnosing diseases, such as cancer, in a mammal, including a human.

FN3 domains that specifically bind to PD-L1, their conjugates, isolated nucleotides encoding the molecules, vectors, host cells, and methods of making and using them are useful in therapeutic and diagnostic applications.

Lipocalin muteins specific to a predetermined antigen can be transduced into a T cell to bring therapeutic benefits to patients in need. In one example, a lipocalin mutein specific to a predetermined antigen (e.g., a target differentially expressed on the surface of a tumor cell) can be transduced into a T cell membrane to serve as an antigen receptor, offering benefits over conventionally deployed antibody-derived protein moieties such as a single chain variable fragment (scFv). Benefits include a more stable structure, leading to superior target engagement, for example. Further, lipocalin muteins specific to a predetermined antigen (e.g. an immunomodulatory target such as an immune checkpoint or costimulatory molecule) can be transduced into a T cell for secretion thereby, bringing an added therapeutic benefit. Specific examples of such modified T cells and methods of making and using the same are provided herein.

Provided herein are proteins comprising a fibronectin based scaffold (FBS) domain, e.g., .sup.10Fn3 molecules, that bind specifically to a target, and wherein the FBS domain is linked at its C-terminus to a region consisting of PmXn, wherein P is proline, X is any amino acid and wherein n is 0 or an integer that is at least 1 and m is an integer that is at least 1, and wherein the PmXn moiety provides an enhanced property to the FBS domain, e.g., enhanced stability, relative to the protein that is not linked to the PmXn moiety.

Fibronectin type III (.sup.10Fn3) binding domains having novel designs that are associated with reduced immunogenicity are provided. The application describes alternative .sup.10Fn3 binding domains in which certain immunogenic regions are not modified when producing a binder in order to maintain recognition as a self antigen by the host organism. The application also describes .sup.10Fn3 binding domains in which HLA anchor regions have been destroyed thereby reducing the immunogenic contribution of the adjoining region. Also provided are .sup.10Fn3 domains having novel combinations of modified regions that can bind to a desired target with high affinity.

The present disclosure relates to recombinant binding proteins comprising a designed ankyrin repeat domain with binding specificity for fibroblast activation protein (FAP). In addition, the disclosure relates to nucleic acids encoding such binding proteins, pharmaceutical compositions comprising such binding proteins or nucleic acids, and the use of such binding proteins, nucleic acids or pharmaceutical compositions in methods for localizing or delivering a biologically active molecule in FAP-expressing tissue, such as tumor tissue, and for treating, diagnosing or imaging diseases, such as cancer, in a mammal, including a human.

The invention relates to fusion proteins comprising at least one extradomain B of fibronectin (ED-B) specific binding domain with high stability in serum and at least one APS domain essentially consisting of or consisting of up to about 80 amino acids selected from alanine, proline, serine, and optionally aspartic acid. The fusion protein further comprises at least one coupling site consisting of at least one cysteine. The invention relates to the use of the fusion proteins or of compositions comprising the fusion proteins for medical applications, such as diagnosis or treatment of cancer or cardiovascular diseases.

Presented herein, in certain embodiments, are bi-specific binding agents comprising an antibody portion that binds specifically to syndecan-1 and a Fynomer portion that binds specifically to a Fibroblast Growth Factor Receptor 3 (FGFR3), compositions thereof and uses thereof for treating a neoplasm.