Dacomitinib, known by its brand name Vizimpro, represents a specialized type of cancer treatment. It belongs to a class of medications referred to as targeted therapies. This medication is designed to interact with specific molecular pathways involved in cancer growth, distinguishing it from broader chemotherapy approaches.
Medical Uses of Dacomitinib
Dacomitinib is specifically approved for the first-line treatment of metastatic non-small cell lung cancer (NSCLC). The term “metastatic” indicates that cancer cells have traveled through the bloodstream or lymphatic system to form new tumors elsewhere in the body.
The medication is not suitable for all NSCLC patients, but rather for those whose tumors possess particular genetic alterations. These specific changes involve epidermal growth factor receptor (EGFR) mutations, namely exon 19 deletions or exon 21 L858R substitution mutations. Before starting dacomitinib, patients undergo testing to confirm the presence of these precise EGFR mutations in their tumor cells.
Mechanism of Action
Dacomitinib functions by targeting the epidermal growth factor receptor (EGFR), a protein that typically signals cells to grow and divide. In certain cancers, mutations within the EGFR gene cause the protein to be constantly active, much like a switch that is stuck in the “on” position. This uncontrolled signaling leads to the rapid and unregulated proliferation of cancer cells.
Dacomitinib is classified as a kinase inhibitor, specifically designed to block the signals emanating from this faulty EGFR protein. It achieves this by forming a strong, permanent bond with specific cysteine residues within the EGFR’s catalytic domain, making it an irreversible inhibitor. This irreversible binding is akin to a key that breaks off in a lock, preventing any further signals from passing through the receptor. By permanently deactivating the mutated EGFR, dacomitinib helps to impede the growth and spread of cancer cells that rely on this pathway.
Administration and Dosage
Dacomitinib is administered as an oral tablet, typically taken once daily. The standard starting dose is 45 mg, swallowed whole with a glass of water. Patients can take this medication with or without food, but it should be taken at the same time each day for consistent drug levels.
If a dose of dacomitinib is missed, it should be skipped, and the patient should simply take the next scheduled dose at the regular time. If a patient vomits after taking a dose, do not take an additional dose; instead, continue with the regular dosing schedule. A healthcare provider may adjust the dose to 30 mg or even 15 mg daily if a patient experiences difficulties tolerating the medication.
Common and Serious Side Effects
Patients taking dacomitinib may experience both common and serious side effects. Common side effects, reported in more than 20% of patients, include diarrhea, skin rash, mouth sores (stomatitis), nail changes (such as paronychia or onycholysis), dry skin, decreased appetite, hair loss (alopecia), conjunctivitis (a condition affecting the eyes), and a decrease in body weight.
Serious side effects necessitate immediate medical attention. Interstitial lung disease (ILD) can occur, manifesting as new or worsening cough, fever, or trouble breathing. Severe skin reactions, which can include blistering, peeling, red lesions, or severe acne, may also develop and sometimes present with fever or chills. Liver problems, indicated by elevated liver enzymes (transaminases), have been reported, and patients may require temporary interruption or dose reduction of the medication if these issues become severe.
Important Patient Considerations
Before initiating dacomitinib treatment, patients should inform their healthcare provider about any pre-existing medical conditions, particularly those affecting the lungs or liver, as these organs can be impacted by the medication. Women who are pregnant, planning to become pregnant, or breastfeeding should discuss these circumstances with their doctor, as dacomitinib has the potential to harm an unborn baby or breastfed infant. Effective birth control methods should be used during treatment and for at least 17 days following the last dose, and breastfeeding should be avoided for the same duration.
Certain medications can interact with dacomitinib. For instance, proton pump inhibitors (PPIs), which reduce stomach acid, should be avoided as they may decrease dacomitinib’s absorption and effectiveness. If acid suppression is needed, alternative medications like H2-receptor antagonists can be considered, but dacomitinib should be taken at least 6 hours before or 10 hours after these agents.