Selpercatinib, also known as Retevmo or LOXO-292, is a targeted therapy used to treat patients with advanced forms of non-small cell lung cancer (NSCLC) and medullary thyroid cancer (MTC) that have specific genetic alterations called RET fusions or mutations. While the drug has shown significant efficacy in clinical trials, it is important to be aware of its potential side effects and take appropriate precautions. This article provides an overview of the most common adverse reactions associated with Selpercatinib and offers guidance on managing these side effects.

Common Adverse Reactions of Selpercatinib

Selpercatinib can cause a variety of side effects, some of which are more common than others. Understanding these side effects can help patients and healthcare providers manage them effectively. The most frequent adverse reactions, occurring in at least 25% of patients, include:

Edema

Edema, or swelling, is a common side effect of Selpercatinib. It typically affects the lower extremities and can be managed by reducing salt intake, increasing physical activity, and using compression garments. If edema becomes severe, patients should consult their healthcare provider for further evaluation and treatment options.

Diarrhea

Diarrhea is another frequent side effect. Patients should stay hydrated and follow a bland diet if diarrhea occurs. Over-the-counter anti-diarrheal medications may also be helpful, but patients should always consult their doctor before taking any new medication.

Fatigue

Fatigue is a common symptom that can significantly impact quality of life. Patients should prioritize rest and maintain a balanced diet rich in fruits, vegetables, and lean proteins. Engaging in light physical activity, such as walking, can also help combat fatigue. If fatigue persists, patients should discuss this with their healthcare provider.

Oral Dryness

Oral dryness, or xerostomia, can be uncomfortable and affect eating and speaking. Patients can alleviate symptoms by drinking plenty of water, using sugar-free gum or lozenges, and applying moisturizing mouth gels. In severe cases, a healthcare provider may prescribe saliva substitutes or other treatments.

The most common grade 3 or 4 laboratory abnormalities (occurring in at least 5% of patients) include lymphopenia, increased alanine aminotransferase (ALT), increased aspartate aminotransferase (AST), hyponatremia, and hypocalcemia. These abnormalities should be monitored regularly to prevent serious complications.

Precautions and Management Strategies

While Selpercatinib offers significant benefits for patients with RET fusion-positive cancers, it is crucial to be aware of the potential risks and take appropriate precautions. The following sections outline key considerations and management strategies for common adverse reactions and specific conditions.

Liver Toxicity

Liver toxicity is a serious concern when using Selpercatinib. Before starting treatment, patients should have baseline liver function tests, including ALT and AST levels. Monitoring should continue every two weeks for the first three months and then monthly thereafter. If liver toxicity is detected, the dose of Selpercatinib may need to be reduced or discontinued temporarily.

Interstitial Lung Disease/Pneumonia

Interstitial lung disease (ILD) or pneumonia can occur in patients receiving Selpercatinib. Patients should be monitored for signs of respiratory symptoms, such as shortness of breath, cough, and fever. If these symptoms appear, treatment should be paused and further investigation conducted. Depending on the severity, the dose may be reduced or the medication permanently discontinued.

Hypertension

Hypertension is a common side effect of Selpercatinib. Patients with uncontrolled hypertension should not start treatment until their blood pressure is optimized. Blood pressure should be monitored weekly for the first month and then at least monthly thereafter. If hypertension becomes severe, the dose of Selpercatinib may need to be adjusted or treatment discontinued.

QT Interval Prolongation

QT interval prolongation is a potentially serious cardiac side effect. Patients at risk, such as those with congenital long QT syndrome or electrolyte imbalances, should have regular ECGs and electrolyte monitoring. If QT interval prolongation is detected, the dose of Selpercatinib may need to be reduced or the medication permanently discontinued.

In addition to monitoring and managing these specific adverse reactions, patients should also be aware of the general precautions and lifestyle adjustments that can help minimize side effects. Regular exercise, a healthy diet, and adequate hydration are essential for maintaining overall well-being during treatment. Patients should also avoid smoking and limit alcohol consumption to reduce the risk of complications.

Embryo-Fetal Toxicity

Selpercatinib can cause harm to the developing fetus. Women of reproductive age should use effective contraception during treatment and for one week after the last dose. Pregnant women should be informed of the potential risks to the fetus. Breastfeeding should be avoided during treatment and for one week after the last dose.

Special Populations

Certain patient groups may require special consideration when using Selpercatinib. For example, pediatric patients under 12 years of age have not been adequately studied, and caution is advised. Patients with renal or hepatic impairment may need dose adjustments based on their specific condition. Elderly patients should be monitored closely for adverse reactions and may benefit from more frequent check-ups.

Drug Interactions

Selpercatinib can interact with other medications, particularly proton pump inhibitors (PPIs), H2 receptor antagonists, and local antacids. These drugs can reduce the effectiveness of Selpercatinib and should be avoided or taken with food if necessary. Patients should inform their healthcare provider about all medications they are taking to avoid potential interactions.

By being aware of these potential side effects and taking appropriate precautions, patients can maximize the benefits of Selpercatinib while minimizing the risks. Regular communication with healthcare providers and adherence to recommended monitoring schedules are essential for a safe and effective treatment experience.