Cancer therapy is largely dependent on general treatment guidelines, and patients undergoing chemotherapy often experience treatment failure with standard drugs. The development of individualized drug therapy through pharmacogenomics has the potential to enhance chemotherapy regimen selection and improve patient outcomes. Antineoplastic agents such as cetuximab and trastuzumab are effective in treating cancers possessing specific genetic biomarker characteristics. Patients need to undergo genetic testing before these agents are administered to ensure appropriate use. Cetuximab has been shown to improve outcomes in metastatic colorectal cancers and head and neck squamous cell carcinomas positive for EGFR. Trastuzumab has shown benefit in human epidermal growth factor receptor 2 (HER2) overexpressing cancers affecting the breast tissue and gastrointestinal tract. High costs associated with the development of targeted drugs and a lack of clinical studies exploring the effects genetic variations can have on drug therapy limit implementation of pharmacogenomics into routine practice. As drug therapy experts, pharmacists need to be aware of advances in the field of pharmacogenomics and facilitate the use of this new class of personalized drugs.