Described herein are methods and compositions useful for inducing maturation of a cardiomyocyte to a mature (e.g., adult) phenotype, such that the function and morphology of the mature cardiomyocyte matches or more closely mimics that of the adult heart. The methods and compositions use Let-7 miRNAs and modified forms thereof. Such methods and compositions permit the study and treatment of adult-onset cardiac diseases, disorders or injuries with mature cardiomyocytes that mimic the heart function of an adult. Methods of using cardiomyocytes matured in this manner for drug identification and drug cardiotoxicity testing are also provided.

The present invention provides compositions and methods for treating cancer in a human. The invention includes relates to administering a genetically modified T cell to express a CAR wherein the CAR comprises an antigen binding domain, a transmembrane domain, a costimulatory signaling region, and a CD3 zeta signaling domain.

Provided methods of obtaining a plurality of T cell receptors specifically recognizing a target tumor antigen peptide from an individual that has clinically benefitted from an immunotherapy, such as Multiple Antigen Specific Cell Therapy. Also provided tumor-specific TCRs, engineered immune cells expressing the TCRs and methods of treating a disease using the engineered immune cells.