Alectinib-d8 is primarily used in research and development as an isotopic-labeled internal standard in mass spectrometry-based analytical methods. It aids in the quantification and detection of alectinib, a drug used to treat non-small cell lung cancer, by ensuring accuracy and precision in pharmacokinetic and metabolic studies. Its deuterated form minimizes interference in analytical assays, providing reliable data for drug monitoring and therapeutic efficacy assessments. This application is crucial for advancing clinical research and optimizing patient treatment strategies.