The present disclosure provides compositions for treating solid tumors, including modified immune cells that specifically target tumor-associated antigens for immunotherapies, wherein expression or activity of T cell immunoreceptor with Ig and ITIM o domains (TIGIT) and/or CD 112R in the modified immune cells is inhibited to improve antitumor functionality of the cells. Alternatively, CD226 is overexpressed in such modified immune cells. Also provided are methods for treating solid tumors, such as tumors formed o by common epithelial cancers.