Deuterated AZ5104 is primarily used in research settings as a metabolically stable analog of AZ5104, which is an EGFR inhibitor. The deuterium substitution enhances the compound’s metabolic stability through the kinetic isotope effect, allowing for improved pharmacokinetic properties. This makes it especially valuable in tracer studies and in vivo experiments where longer half-life and reduced degradation are critical. It is commonly employed in oncology research to study resistance mechanisms in non-small cell lung cancer (NSCLC), particularly against T790M and C797S mutations in EGFR. Due to its enhanced stability, it supports more accurate tracking of drug distribution, metabolism, and target engagement in preclinical models. Its application also extends to mass spectrometry-based quantification, where deuterated compounds serve as internal standards to improve analytical precision.