Modified chimeric receptors and related compositions and methods

Provided are chimeric receptors for engineering cells for adoptive therapy, including T cells, and the genetically engineered cells. In some embodiments, the chimeric receptors, such as chimeric antigen receptors (CARs) are modified in a junction region by one or more amino acid modifications such that peptide fragments of such region exhibit a lower binding affinity for a human leukocyte antigen (HLA) and/or the region exhibits reduced immunogenicity, including following administration to a subject. In some aspects, also provided are methods and compositions for engineering and producing cells expressing such chimeric receptors, compositions containing the cells, and method for their administration to subjects. In some embodiments, features of the chimeric receptors and engineered cells containing the chimeric receptors result in methods that provide for increased or improved activity, efficacy and/or persistence.