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Imatinib is a 2-phenylamino-pyrimidine derivative protein that is a medication used to manage and treat chronic myelogenous leukemia, gastrointestinal stromal tumors, and other malignancies. It is in the tyrosine-kinase inhibitors class of drugs. This activity reviews the indications, action, and contraindications for imatinib as a valuable agent in the treatment of several oncologic indications. In addition, this activity will highlight the mechanism of action, adverse event profile, and other key factors (e.g., dosing, administration, monitoring, relevant interactions, and toxicity) pertinent for members of the healthcare team for treating patients with chronic myelogenous leukemia, gastrointestinal stromal tumors, and other related conditions. Objectives: Identify the mechanism of action of imatinib. Describe the potential adverse effects of imatinib. Review the appropriate monitoring/toxicity of imatinib, including significant drug interactions. Explain interprofessional team strategies for improving care coordination and communication to improve outcomes for patients receiving imatinib. Access free multiple choice questions on this topic.

Treatment with imatinib is associated with hematologic toxicity (anemia, neutropenia, and thrombocytopenia) Treatment with imatinib is associated with hepatotoxicity. Treatment with imatinib is associated with hypereosinophilic cardiac toxicity in patients with hypereosinophilic syndrome. Treatment with imatinib can cause fetal harm to a pregnant woman (Imatinib has demonstrated teratogenicity in rats at the 800 mg/day equivalent human maximum dose)[14] Treatment with imatinib is associated with renal toxicity. Treatment with imatinib is associated with dermatologic toxicities, including erythema multiforme and Stevens-Johnson syndrome.[18]

Imatinib is a powerful targeted therapeutic drug for several types of cancer. Despite showing a favorable risk/benefit tradeoff in several clinical trials and being FDA-approved for nearly two decades, it does require close monitoring for safety. In addition to the prescribing physician, pharmacists and nurses are responsible for educating the patient on the potential side effects of the drug. While most side effects occur in the first two years of use, many patients will be on chronic therapy for many years, so it is essential to stay vigilant in monitoring for side effects.[20] Particularly severe side effects that require careful monitoring include Stevens-Johnson syndrome, gastrointestinal perforations/hemorrhage, fluid retention, organ (cardiac, renal, and liver) failure, and hematologic toxicities. Additionally, imatinib does have several interactions with other medications that are also metabolized by CYP3A4. The pharmacist needs to monitor all medications the patient takes to ensure no interactions. This requires proper dose adjustments due to potential drug-drug interactions if concurrent medications are necessary. The clinicians, nurses, and pharmacists should regularly check liver function, renal function, and complete blood counts to monitor for organ damage or immunosuppression and adjust imatinib dosing as necessary while continually informing the ordering clinician. Nursing will notably have the optimal chance to see any issues that arise since they will have the first contact with the patient, so they must be familiar with the adverse event and interaction profile. This is where an oncology specialty nurse is invaluable. All interprofessional team members are responsible for monitoring the patient's progress and reporting any status changes to the rest of the team so corrective measures can be taken if necessary. This also includes meticulous documentation so that everyone on the healthcare team has the same patient data set from which to work. This collaborative paradigm exemplifies the type of interprofessional teamwork the healthcare team requires to administer imatinib effectively to achieve optimal patient outcomes while minimizing patient risks. [Level 5]

Nursing will notably have the optimal chance to see any issues that arise since they will have the first contact with the patient, so they must be familiar with the adverse event and interaction profile. This is where an oncology specialty nurse is invaluable. All interprofessional team members are responsible for monitoring the patient's progress and reporting any status changes to the rest of the team so corrective measures can be taken if necessary. This also includes meticulous documentation so that everyone on the healthcare team has the same patient data set from which to work. This collaborative paradigm exemplifies the type of interprofessional teamwork the healthcare team requires to administer imatinib effectively to achieve optimal patient outcomes while minimizing patient risks. [Level 5] It was one of the first targeted therapeutics to reach the market and also now is generic. Imatinib presents interesting time-series data on the costs of precision medications. At approval in 2001, a one-month supply of the 400mg daily dose cost $2200 in the US.[21] In 2010, this cost had ballooned to $5143 per month, and by 2018 it was $10620 per month.[22] A generic form of imatinib was launched in the US in 2015 at a 30% discount on the branded price (which was substantially higher than the 82% discount at which the Canadian generic was launched).[23] Because of dysfunctional market maximizing forces, ironically, the price of imatinib generics was higher than the original branded version, and pricing relief remained elusive for years. However, during 2018, generic imatinib pricing finally dropped below its original launch price, yet it still cost several thousand dollars per annum despite being generic. With expensive therapies such as imatinib, the interprofessional healthcare team, including clinicians, nurses, pharmacists, and other healthcare professionals (such as social workers or charity assistance programs), must coordinate care and advocate for coverage to maximize access to life-saving medications.