How to Cite: Al-Ammiri, H. H., Mohammed, M. M., Hameedi, A. D., & Alkhalidi, N. M. (2022). Validity of novel techniques (modified tissue ELISA and IHC) in correlation and comparison for detection of patients with gastric cancer using cut off values of check point inhibitor (PD-1 & PD-L1). International Journal of Health Sciences, 6(S4), 5737–5744. https://doi.org/10.53730/ijhs.v6nS4.9975 International Journal of Health Sciences ISSN 2550-6978 E-ISSN 2550-696X © 2022. Manuscript submitted: 27 March 2022, Manuscript revised: 18 May 2022, Accepted for publication: 9 June 2022 5737 Validity of novel techniques (modified tissue ELISA and IHC) in correlation and comparison for detection of patients with gastric cancer using cut off values of check point inhibitor (PD-1 & PD-L1) Hind H. Al-Ammiri BVM&S, MSC, Immunology, Microbiology department, collage of Vet. Medicine, Baghdad University Corresponding author email: Dr.hindhamid@gmail.com Mohammed M. Mohammed MBChB, MSc, FICMs/Path, Microbiology department, collage of Medicine, Baghdad University Ameer D. Hameedi MBChB, FICMS/ Path, Microbiology department, collage of Vet. Medicine, Baghdad University Nawal M. Alkhalidi MBChM CABm, FiCMS GE and H, Microbiology department, collage of Medicine, Baghdad University Abstract---Background: One of the most common malignancies involving the gastrointestinal tract is gastric cancer. It is categorized as an aggressive disease with poor treatment outcome, as most patients remain undetected until later stages, a multifactorial disease involving both genetic and environmental factors in etiology; a wide variance in the occurrence of gastric cancer in various geographical regions (Abdi-Rad et al., 2006, Abuderman, 2019). Checkpoint inhibitor therapy is revolutionizing the oncology disease management process. despite the fact that gastric cancer is a common malignancy with a poor prognosis, relatively little attention has been drawn and attracted to the treatment and diagnosis of this disease by checkpoint inhibitor therapy (Kang YK, 2017). Objectives: The aims of this study To compare between (a modified ELISA method) and immunohistochemistry (IHC) for those immunological markers PD-1,