Conditionally active chimeric antigen receptors for modified t-cells

A chimeric antigen receptor for binding with a tumor specific target antigen, comprising:

• i. at least one antigen specific targeting region evolved from a parent or wild-type protein or a domain thereof and having a decrease in activity in an assay at a normal physiological condition compared to the activity of the antigen specific targeting region in an assay at an aberrant condition that deviates from the normal physiological condition;
• ii. a transmembrane domain;
• and
• iii. an intracellular signaling domain;
• wherein the tumor specific target antigen is selected from Axl and ROR2 .

A method for producing a chimeric antigen receptor comprising at least one antigen specific targeting region, a transmembrane domain and an intracellular signaling domain, said method comprising the steps of

• generating the at least one antigen specific targeting region from a parent or wild-type protein or a domain thereof that binds specifically with a tumor specific target antigen, by:
• i. evolving the DNA which encodes the parent or wild-type protein or a domain thereof using one or more evolutionary techniques to create mutant DNAs;
• ii. expressing the mutant DNAs to obtain mutant polypeptides;
• iii. subjecting the mutant polypeptides to an assay under a normal physiological condition and to an assay under an aberrant condition that deviates from the normal physiological condition;
• and
• iv. selecting the at least one antigen specific targeting region from the mutant polypeptides expressed in step (ii) which exhibits a decrease in activity in the assay at the normal physiological condition compared to the activity in the assay under the aberrant condition;
• wherein the tumor specific target antigen is selected from the group consisting of tyrosine kinase growth factor receptors that are overexpressed on a surface of a cancer cell.