The efficacy of neoantigen-reactive T cells (NRT) therapy in solid tumors, encompassing aspects such as infiltration, recognition, cytotoxicity, and enduring persistence, is notably influenced by the immunological microenvironment. This study endeavors to investigate whether the co-administration of pemetrexed and cisplatin augments the therapeutic efficacy of NRT therapy in lung cancer. Neoantigens were predicted using a comprehensive analysis of mutation data from Lewis lung carcinoma cells and mouse tail tissues. The immunogenicity of NRT cells was assessed through flow cytometry and IFN-γ ELISpot assays. A mouse model of NSCLC was used to investigate the anti-tumor effects of NRT combined with chemotherapy. The combination of NRT cells and chemotherapy significantly inhibited tumor growth in a mouse model, increased CD3+/CD137+ T cells to promote IFN-γ secretion from NRT cells, and up-regulated the levels of inflammatory cytokine proteins including IFN-γ, TNF, IL-6 and IL-10. Immunofluorescence analysis confirmed increased T-cell infiltration in tumor tissues without adverse effects on vital organs. In addition, transcriptome analyses indicated that the tumor microenvironment was altered to favor M1-like macrophages with an increased M1/M2 ratio, creating a pro-inflammatory environment. The integration of NRT with frontline chemotherapy for lung cancer could yield profoundly ideal therapeutic outcomes.