Proteolytically cleavable chimeric polypeptides and methods of use thereof

A host cell comprising:

• a) a nucleic acid encoding a chimeric polypeptide comprising, from N-terminal to C-terminal and in covalent linkage:
• i) an extracellular domain comprising a specific binding member that specifically binds to a target molecule present on the surface of a target cell;
• ii) a proteolytically cleavable Notch receptor polypeptide comprising Lin12 Notch repeats, a heterodimerization (HD) domain, a transmembrane domain and one or more proteolytic cleavage sites;
• and
• iii) an intracellular domain comprising a transcriptional activator;
• b) a nucleic acid encoding a chimeric bispecific binding member, an anti-Fc chimeric antigen receptor (CAR), an innate-immune response inducer, or an immune suppression factor operably linked to a transcriptional control element responsive to the transcriptional activator, wherein binding of the specific binding member to the target molecule induces cleavage of the Notch receptor polypeptide at the one or more proteolytic cleavage sites, thereby releasing the intracellular domain, activating the transcriptional control element and causing the chimeric bispecific binding member, the anti-Fc CAR, the innate-immune response inducer, or the immune suppression factor to be expressed,
• wherein the chimeric bispecific binding member comprises a binding domain specific for a cancer antigen and a binding domain specific for CD3 or Natural Killer Group 2D (NKG2D) receptor.

A host cell comprising:

• a) a nucleic acid encoding a chimeric polypeptide comprising, from N-terminal to C-terminal and in covalent linkage:
• i) an extracellular domain comprising a specific binding member that specifically binds to a target molecule present on the surface of a target cell;
• ii) a proteolytically cleavable Notch receptor polypeptide comprising Lin12 Notch repeats, a heterodimerization (HD) domain, a transmembrane domain and one or more proteolytic cleavage sites;
• and
• iii) an intracellular domain comprising a transcriptional activator;
• b) a nucleic acid encoding a chimeric bispecific binding member, an anti-Fc chimeric antigen receptor (CAR), an innate-immune response inducer, or an immune suppression factor operably linked to a transcriptional control element responsive to the transcriptional activator, wherein binding of the specific binding member to the target molecule induces cleavage of the Notch receptor polypeptide at the one or more proteolytic cleavage sites, thereby releasing the intracellular domain, activating the transcriptional control element and causing the chimeric bispecific binding member, the anti-Fc CAR, the innate-immune response inducer, or the immune suppression factor to be expressed,
• wherein the host cell further comprises a nucleic acid encoding an antibody specific for a cancer antigen present on the surface of a cancer cell and comprising an Fc region that is bound by the anti-Fc CAR.

A host cell comprising:

• a) a nucleic acid encoding a chimeric polypeptide comprising, from N-terminal to C-terminal and in covalent linkage:
• i) an extracellular domain comprising a specific binding member that specifically binds to a target molecule present on the surface of a target cell;
• ii) a proteolytically cleavable Notch receptor polypeptide comprising Lin12 Notch repeats, a heterodimerization (HD) domain, a transmembrane domain and one or more proteolytic cleavage sites;
• and
• iii) an intracellular domain comprising a transcriptional activator;
• b) a nucleic acid encoding a chimeric bispecific binding member, an anti-Fc chimeric antigen receptor (CAR), an innate-immune response inducer, or an immune suppression factor operably linked to a transcriptional control element responsive to the transcriptional activator, wherein binding of the specific binding member to the target molecule induces cleavage of the Notch receptor polypeptide at the one or more proteolytic cleavage sites, thereby releasing the intracellular domain, activating the transcriptional control element and causing the chimeric bispecific binding member, the anti-Fc CAR, the innate-immune response inducer, or the immune suppression factor to be expressed,
• wherein the innate-immune response inducer is a bacterial protein or fragment thereof, a viral protein or fragment thereof, a fungal protein or fragment thereof, or a protein or fragment thereof expressed by a mammalian parasite.