Background: Although checkpoint inhibitor immunotherapy and adoptive T-cell therapy revolutionized cancer treatments, such approaches suffer either from lack of target specificity for checkpoint inhibitors or inability to target intracellular tumor-related antigens from CAR-T therapy. Here, we report the development of novel Tavo Immune Modulator (TIM) biologics molecules which can specifically recognize tumor antigen-specific T cells through an engineered pMHC complex with peptides derived from intracellular tumor-related antigens. These molecules can selectively activate such T cells through engineered T cell co-stimulatory modulators for enhanced tumor cell killing. Methods: NY-ESO-1 and MAGE-A10 TIM molecules were constructed as fusions of HLA-A*02:01 MHC complexed with either NY-ESO-1 (157-165) or MAGE-A10 (254-262) epitope peptides at the N-termini and various T cell costimulatory modulators at the C-termini of IgG heavy and light chains. TIM molecules were expressed in Expi293 cells and purified by Protein A affinity chromatography. Specific binding of TIM with cancer specific T cells was evaluated by immunostaining. The activation and proliferation of tumor specific CD8+ T cells were confirmed in T cell activation and recall assays. Results: Both NY-ESO-1 and MAGE-A10 specific TIM molecules were generated which recognized corresponding tumor specific T cells. NY-ESO-1 TIM engineered with IL2 could activate NY-ESO-1 specific CD8+ T cell exclusively. Engineering additional T cell costimulatory factors along with IL2 on NY-ESO-1 TIM molecule could further boost T cell proliferation and activation in T cell recall assays. Besides NY-ESO-1, combinations of T cell costimulatory factors with MAGE-A10 TIM molecules enhanced specific T cell activation. Additional in vitro and in vivo studies are ongoing to demonstrate efficacy of such novel TIM molecules in eliminating different types of NY-ESO-1 and MAGE-A10 which are over-expressed on tumor cells. Conclusions: This study demonstrates the utility of NY-ESO-1 and MAGE-A10 TIM molecules in the selective recognition and activation of tumor antigen-specific T cells. Such novel biologics molecules may provide target specificity in tumor treatment, and potential targeting of intracellular tumor-related antigens presented as peptides in MHC complexes on cell surfaces. Selective activation of tumor-specific T cells may provide a unique method for the treatment of various solid tumors and warrants further investigation.