Tumor microenvironment is a complex multistep event which involves several hallmarks that transform the normal cell into cancerous cell. Designing the novel antagonistic molecule to reverse the tumor microenvironment with specific target is essential in modern biological studies. The novel 4-phenyl-2-phenoxyacetamide thiazole analogues 8a-ab were synthesized in multistep process, then screened and assessed for cytotoxic and anti-proliferative effects in vitro against multiple cancer cells of different origin such as MCF-7, A549, EAC and DLA cells which revealed that compound 8f with fluoro and methyl substitute has potential cytotoxic efficacy with an average IC50 value of ˜ 13 μM. The mechanism of cytotoxicity assessed for anti-tumor studies both in ascites and solid tumor models in-vivo inferred the regressed tumor activity. This is due to changes in the cause of tumor microenvironment with crackdown of neovascularization and evoking apoptosis process as assessed by CAM, corneal vascularization and apoptotic hallmarks in 8f treated cells. The molecular gene studies inferred involvement of HIF-1upregulation and stabilization of p53 which are interlinked in signaling as conferred by immunoblot analysis.