The present invention relates to compositions and methods for using a minibody. Minibodies described herein comprise a secretion signal, a variable heavy chain fragment, a variable light chain fragment, a constant chain fragment, and a hinge domain between the variable light chain fragment and the constant chain fragment. One aspect includes a nucleic acid encoding a minibody. Other aspects include compositions comprising a minibody and a modified T cell comprising a nucleic acid encoding a minibody. Also included are methods and pharmaceutical compositions comprising the modified T cells for adoptive therapy and treating a condition, such as cancer.