Vonjo is a medicine called a kinase inhibitor that is used to treat certain types of a blood disorder called myelofibrosis. Myelofibrosis is a type of blood cancer that causes scarring (fibrosis) in your bone marrow, which affects how your body makes blood cells. When your bone marrow has trouble making blood cells, other organs such as your spleen, liver, or lungs may begin to take over this function. This can cause these organs to become enlarged, especially the spleen (splenomegaly). This can create pressure on the organs near your spleen, leading to symptoms such as feeling full quickly while eating, discomfort in your abdomen, and pain under your left rib cage. Vonjo helps shrink an enlarged spleen and may relieve symptoms related to the condition.
How Does Vonjo Work for Myelofibrosis?
Vonjo works by targeting certain proteins in the body called kinases. These kinases cause the blood cells to grow out of control. Vonjo blocks proteins on blood cells called Janus-associated kinase 2 (JAK2) and FMS-like tyrosine kinase 3 (FLT3). These proteins help cells grow and divide. By blocking these proteins, Vonjo helps shut off signals that cause abnormal blood cell growth and helps decrease symptoms of myelofibrosis.
What Kinds of Myelofibrosis Does Vonjo Treat?
Vonjo treats intermediate or high-risk myelofibrosis in people with a platelet count below 50 x 109/L.
How Will I Get Vonjo?
Vonjo is taken as a capsule that you swallow. It is usually taken by mouth twice a day. You should take your dose around the same time every day. If you miss a dose, skip the dose and take the next dose when it is due and return to the normal schedule. You should not take two doses at one time to make up for a missed dose. You should not open, break, or chew capsules.
Your dose of Vonjo may need to be lowered if you are taking certain medications. You should tell your health care provider about all of the medications or supplements you are taking.
You may need a lower dose of Vonjo if you have certain side effects. Your health care provider will decide what dose of Vonjo is right for you.
How Was Vonjo Studied for Myelofibrosis?
Vonjo was studied in people with intermediate or high-risk myelofibrosis who had splenomegaly and 100 x 109/L platelets or less. People in this study got either Vonjo once a day, Vonjo twice a day, or best available therapy (BAT). This study looked at what percentage of people had a spleen volume reduction (SVR) of at least 35%. SVR measures a decrease in the size of the spleen. There were 311 people in this study and they were evenly split amongst the groups. The average age was 68 (range 32 to 91) and 55% of people were male. Eighty six percent of people were White, and the percentages of other races were not provided.
In people who had a platelet count of 50 x 109/L or less, 29% of people in the Vonjo twice daily group had a SVR of at least 35%, versus only 3% in the BAT group. The median reduction in spleen volume for these people was 27.3% in the Vonjo twice daily group compared to 0.9% in the BAT group. This means that significantly more people in the Vonjo twice daily group had SVR than the people in the BAT group.
What Are the Possible Side Effects of Vonjo, and How Can I Prevent or Manage Them?
Vonjo may cause severe side effects such as bleeding problems, blood clots, and heart problems. Contact your health care provider right away if you have symptoms of bleeding such as dark urine or tarry stool, coughing or vomiting up blood, or confusion, dizziness, or severe headache, or symptoms of heart problems or blood clots such as fast heartbeat, pain in your chest, feeling short of breath, or pain or swelling in your legs. You should also tell your health care provider if you plan to have surgery or an invasive procedure.
Vonjo can cause low blood counts, including low platelets (thrombocytopenia) and low red blood cells (anemia). Thrombocytopenia can cause you to bruise or bleed easier than normal. Things you can do to prevent this include using an electric shaver instead of a razor, using a soft bristled toothbrush to brush your teeth, and avoiding contact sports. Anemia can make you feel more tired than usual and have shortness of breath. Eating foods rich in iron such as spinach and red meat may help boost your energy. Contact your health care provider if you have these symptoms so your blood counts can be monitored.
Severe infections can happen while taking Vonjo. You can help reduce your risk of developing an infection by washing your hands often and staying away from people with infections, colds, or the flu. If you are at high risk for getting an infection, your health care provider may prescribe a medicine to help prevent infections. You should contact your health care provider right away if you develop a fever or any other signs of an infection such as a sore throat or cough.
Vonjo may cause gastrointestinal (GI) side effects such as nausea and diarrhea. Your health care provider may give you certain medicines to prevent these side effects from happening as well as medicines to treat them. Eating bland food and smaller meals throughout the day can help with symptoms of nausea. If you have diarrhea, your health care provider may recommend that you start taking diarrhea medicine and drink more fluids to avoid losing too much of your body's water (dehydration).
If you have certain side effects while you take Vonjo, your health care provider may need to change your dose or how often you get your dose, temporarily pause, or even stop your medicine altogether. This will depend on how severe the side effect is that you have and what type of treatment it requires.
What Medicine Interactions Can Happen With Vonjo?
Several medicines can affect the blood levels of Vonjo. This may increase the risk of side effects or decrease the effect of Vonjo. Tell your doctor if you are taking the antibiotic clarithromycin, any medicines for HIV, or any medicines for a fungal infection.
Vonjo may also affect how well hormonal contraceptives (birth control) work during your treatment with Vonjo and for 30 days after you stop taking it. Talk to your doctor about other methods of birth control that may work for you.
If you are taking another kinase inhibitor when you start Vonjo, you will have to slowly stop taking it (taper). Your health care provider can help you stop taking your kinase inhibitor.
This is not a complete list of medicines that may interact with Vonjo. Tell your pharmacist or health care provider about all the prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, or other supplements you take or have recently taken. This will help them determine if there are any interactions with Vonjo or if you need a dosage adjustment.
How Do I Know If Vonjo Is Working?
Vonjo should start working in a few days, but it may take several weeks to see an improvement. Your health care provider will regularly check how well Vonjo is working for your cancer through looking at results of tests such as blood tests, CT scans, or MRI scans.
How Can I Get Vonjo?
Vonjo requires a prescription from a health care provider. Vonjo is available through specialty pharmacies or distributors only. There is a copay savings program available from the drugmaker that may cost you as little as $25 for your monthly copay for your Vonjo prescription. Whether you are eligible depends on your insurance coverage. You can find out more by visiting www.vonjo.com/vonjo-patient-assistance-and-support-programs or by calling 888-284-3678.
