Larotrectinib (Vitrakvi®) is a form of targeted therapy known as a “tissue agnostic” drug, which means it can be used to treat different types of cancer, as long as they all have the same biomarker. This drug can be used in both adults and children with solid tumor cancers that test positive for certain neurotrophic receptor tyrosine kinase (NTRK) genes, have also metastasized (spread to other parts of the body) or if surgery to treat the cancer is probable to cause serious problems, and have gotten worse during other types of treatment or there are no other available treatment options.1
Tissue agnostic drugs are an exciting new breakthrough in cancer treatment because scientists are looking at the biology of the cancer, instead of merely the type of cancer, allowing for more specialized and targeted treatments. Development of these types of therapies could potentially translate into more effective treatment, resulting in better quality of life.
How does larotrectinib work?
Larotrectinib inhibits tropomyosin receptor kinases, which are encoded by genes like NTRK1, NTRK2, and NTRK3.2 When there are mutations in these genes, these can facilitate oncogenic changes, leading to the development of cancer.2 Larotrectinib shows anti-tumor activity in cells in which these mutated genes occur.
What are the possible side effects of larotrectinib?
As with any medication, when taking larotrectinib, adverse effects may occur. Possible side effects of larotrectinib include fatigue, peripheral swelling, fever, nausea and vomiting, diarrhea, abdominal pain, dizziness, headache, cough, weight gain, muscle pain or weakness, and joint pain.2 Laboratory counts may be affected as well, especially liver enzymes.
Possible neurological side effects may include confusion, difficulty concentrating, issues with sleeping, memory impairment, and mood changes.2
This is not an exhaustive list of all potential side effects of larotrectinib. Talk to your healthcare provider or pharmacist for further information.
Things to know about larotrectinib
If you are pregnant, plan to become pregnant, or are breastfeeding or plan to breastfeed, talk with your doctor. Larotrectinib can cause harm to a developing fetus and should not be taken by women who are pregnant. While taking larotrectinib, males with female partners who can become pregnant, and females who can become pregnant, should both use contraceptives during treatment and for a period of time after completing treatment (patients should discuss appropriate birth control methods, and how long they need to use them, with their doctor). Females should not breastfeed during larotrectinib treatment and for a period of time following the final dose (patients should discuss breastfeeding considerations with their doctor).2
Because of the changes in laboratory tests (especially liver enzyme levels), individuals taking this medication should get ALT and AST levels checked every two weeks in the first month of taking larotrectinib, and then monthly and as needed after that.3
This drug may interact with other medications. Tell your doctor about any other medication, drug, vitamin, over-the-counter drugs, or supplement that you take, as well as any other health conditions. While taking larotrectinib, do not take St. John’s wort, eat grapefruit, or drink grapefruit juice, as these may cause unsafe changes in the levels of larotrectinib in your body.2
Larotrectinib may impair fertility in female individuals, so talk with your doctor if you have any concerns about this.2
Receiving larotrectinib
This drug can be taken by capsule or by oral solution and can be used interchangeably. Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their Vitrakvi regimen.
If adverse reactions occur, depending on the severity of the adverse reaction, your doctor may make changes to your prescribed dosage. It’s not recommended that larotrectinib be taken with strong CYP3A4 inhibitors, but if this is unavoidable, dosage modifications for coadministration may be made by your doctor.2 Your doctor will talk with you further about what modifications and dosing schedules will be like, and it is important that you tell your doctor about all other medications (prescription and over-the-counter) that you take, and that you follow your doctor’s instructions regarding your medication regimen.
For more information, read the full prescribing information of larotrectinib.
