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Division of Hematology Oncology
Department of Medicine
University of California, Los Angeles
Santa Monica, California
Julia LaBarbera, MSN, RN, AGACNP-BC: consultant/advisor/speaker: Bio-Theradiagnostics, Cancer Network/MJH Life Sciences.
Approval of adjuvant abemaciclib in combination with endocrine therapy for hormone receptor (HR)‒positive/human epidermal receptor 2 (HER2)‒negative breast cancer based on the monarchE clinical trial has changed the paradigm of treatment options for early breast cancer (EBC), particularly for individuals who have positive lymph nodes and are at high risk for recurrence. Oral targeted therapies such as abemaciclib come with their own unique adverse events (AEs), which are important to educate patients about and for healthcare professionals (HCPs) to promptly identify and manage, especially in the EBC setting. Successful management of AEs related to oral targeted therapies enables HCPs to balance quality of life, maximize drug efficacy, and ensure optimal patient outcomes. The development of CCO’s Interactive Decision Support Tool is valuable in helping HCPs to determine the most appropriate course of action for symptom management with abemaciclib.
Common AEs Related to Targeted Therapy With Abemaciclib
Diarrhea is very common with abemaciclib, occurring in 84% of monarchE clinical trial participants, with a median time to onset of 8 days. Usually, cases are low grade and manageable. It is extremely important to discuss diarrhea with patients when initiating treatment. Counsel patients to promptly start antidiarrheals with any watery stools or more than 3 bowel movements above their baseline. Encourage increased oral hydration (ideally 1-2 liters of fluid daily) and try bland/low-fiber foods until diarrhea improves. Atropine may be indicated when loperamide alone is insufficient at controlling symptoms. Dose interruptions and reductions may be required for severe cases of diarrhea. Monitor electrolytes, including magnesium and phosphorus, every 2 weeks for the first 2 cycles and monthly thereafter, or as clinically indicated.
Cytopenias, particularly neutropenia, can occur with any of the CDK4/6 inhibitors, but they often are less severe with abemaciclib. Monitor blood counts every 2 weeks when initiating therapy and monthly thereafter, or as clinically indicated. Educate patients regarding the risks associated with neutropenia, and advise them to report signs or symptoms of fever or infection during therapy. Dose interruptions may be indicated during patient illness, and dose reductions may be required based on the severity of hematologic toxicity.
A small but significant risk of interstitial lung disease is associated with abemaciclib. It is extremely important to educate patients regarding this risk and encourage them to promptly report any new cough, shortness of breath, activity intolerance, or fever. Monitor for clinical signs of interstitial lung disease at follow-up visits, and do not delay imaging for new cough, wheezing, hypoxia, or any other suspicious exam findings. Dose interruptions and treatment with corticosteroids can be considered based on patient scenario.
Venous thromboembolic events are associated with abemaciclib, but incidence is low. Monitor for signs and symptoms of thrombus or pulmonary embolism, and counsel patients to report these as soon as possible. Rash also may occur. Management depends on the severity and extent of symptoms but may include oral antihistamines, topical or oral corticosteroids, and treatment interruption or dose reductions. Hepatoxicity also may be seen with abemaciclib. Follow liver function tests at least monthly or as clinically indicated. Interrupt therapy or modify the dose depending on severity of lab abnormality.
A downloadable patient resource is available here to assist you in educating your patients about adjuvant abemaciclib.
An Interactive Decision Support Tool for AE Management
CCO’s Interactive Decision Support Tool for managing AEs with oral targeted therapies for HR-positive/HER2-negative breast cancer is a valuable resource for educating HCPs and optimizing AE management. The tool was developed in collaboration with top breast cancer experts and can be used in both the adjuvant and metastatic settings. The user answers a series of questions regarding patient characteristics, whether oral targeted therapy has been initiated and which one, whether an invasive procedure is anticipated, or whether the patient is experiencing an AE. If an AE is present, the type and severity also are indicated by the user. Based on the information entered, the user receives expert-based recommendations for the specific patient scenario. This can be particularly helpful when determining whether treatment interruptions or dose reductions may be indicated. It is extremely easy to use, is completed in a matter of minutes, and can reduce delays in patient care.
As the data regarding adjuvant abemaciclib continue to emerge, it is important to remember that late or long-term effects from targeted therapy in the adjuvant setting are yet unknown. There may be long-term effects on gastrointestinal, pulmonary, or cardiac function that are not yet elucidated, and patients need to be comfortable with this. HCPs need to counsel patients of childbearing potential regarding possible embryo-fetal toxicity and the importance of contraception before, during, and for at least 3 months after treatment. HCPs also need to be mindful of the financial toxicity that novel adjuvant treatments may carry and work with our pharmacy team and other available resources to screen patients for co-pay assistance or grant support, where applicable.
Overall, most AEs related to adjuvant oral targeted therapy for HR-positive/HER2-negative EBC are low grade and manageable. It is important to remember that a patient may be more willing to tolerate an AE in the adjuvant setting, where prevention of recurrence is central to long-term outcomes and prognosis. HCPs must balance aggressive management of AEs with quality of life to optimize patient response. As HCPs, we need to screen patients routinely for presence and severity of AEs, as patients may be less willing to disclose such events due to fear of stopping therapy. We should remind patients that many adjunct treatments exist for symptom management and that dose reductions or modifications are important components in enhancing adherence to therapy without reducing efficacy.
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