Drug Detail:Gleevec (Imatinib)
Drug Class: BCR-ABL tyrosine kinase inhibitors
1. How it works
- Gleevec is a brand (trade) name for imatinib which may be used to treat chronic myeloid leukemia (CML), Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL), and some other conditions.
- Gleevec works by specifically inhibiting the enzyme BCR-ABL tyrosine kinase, which is an abnormal enzyme involved in the development of blood cancers like CML, ALL, certain skin cancers, and some types of tumors of the stomach or intestine. Gleevec stops the proliferation of cancer cells and induces cell death in BCR-ABL-positive cell lines as well as fresh leukemic cells in Philadelphia chromosome-positive CML. It also inhibits receptor tyrosine kinases for PDGF (platelet-derived growth factor), SCF (stem cell factor), and the KIT protein.
- Gleevec belongs to the class of medicines known as BCR-ABL tyrosine kinase inhibitors (TKIs).
2. Upsides
- May be used for the treatment of newly diagnosed Philadelphia-positive CML (Ph+ CML) in adults and children in the chronic phase.
- Can be used to treat Ph+CML in blast crisis, accelerated phase, or chronic phase after failure of interferon-alpha treatment.
- Consider for adults with relapsed or refractory Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) or children with newly diagnosed Ph+ ALL in combination with chemotherapy.
- Can be used to treat myelodysplastic/myeloproliferative diseases (MDS/MPD) associated with platelet-derived growth factor receptor (PDGFR) gene re-arrangements in adults.
- Consider for adults with aggressive systemic mastocytosis without the D816V c-Kit mutation or with c-Kit mutational status unknown.
- May also be used to treat other conditions, such as Hypereosinophilic syndrome (HES), certain types of chronic eosinophilic leukemia (CEL), dermatofibrosarcoma protuberans (DFSP), and Kit+ gastrointestinal stromal tumors (GIST).
- May be available for other conditions as part of a clinical trial.
- Gleevec is a targeted treatment and is not chemotherapy. It may also be called a cancer growth inhibitor.
- Works by switching off (inhibiting) the tyrosine kinase made by the BCR-ABL1 gene in leukemia cells, which slows or stops the bone marrow from making abnormal white blood cells. It also allows the leukemia cells to mature and die.
- Was the first medicine approved by the FDA in 2001 to specifically block the BCR-ABL tyrosine kinase protein, a target for certain forms of leukemia. A blood test can detect the presence of the BCR-ABL gene or other genes or mutations that may be fueling cancer growth.
- Available as 100mg and 400mg tablets.
3. Downsides
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Fluid retention (superficial edema), nausea or vomiting, muscle cramps, muscle or joint pain, diarrhea or constipation, rash, fatigue, headache, abdominal pain or dyspepsia, nasopharyngitis, hemorrhage, cough, dizziness, fever, weight gain, insomnia, loss of appetite, hair loss, and depression are the most common side effects reported. Weigh and monitor patients regularly for signs of fluid retention and investigate rapid weight gain carefully.
- Gleevec may increase the risk of infection, such as upper respiratory tract infections or the flu because it can reduce the number of white blood cells in your blood (called neutropenia). Regular blood cell counts are required.
- May increase the risk of bleeding and bruising because it can reduce the number of platelets in the blood. Monitor for any unexplained bruising or bleeding and consider a platelet transfusion if necessary. Serious bleeding has also been reported. Gastrointestinal tumor sites may have been the source of GI hemorrhages.
- Can also cause anemia (low number of red blood cells) and a blood transfusion may be needed.
- Can cause a rash, itching, and increase sun sensitivity.
- Gleevec can cause drowsiness, eye pain, dry or watery eyes, or blurred vision which may affect a person's ability to drive or operate machinery. A bitter or metallic taste in the mouth may also occur.
- Can cause a decline in renal function. Evaluate renal function before initiating Gleevec and monitor throughout treatment. People at higher risk include those with preexisting impairment, diabetes, high blood pressure, and heart failure. Reduce the dosage by 50% in those with moderate renal impairment (maximum dosage 400mg in moderate renal impairment and 100mg with severe renal impairment).
- Liver toxicity may occur.
- In large clinical trials, elevations in serum aminotransferase levels during dasatinib therapy occurred in up to 50% of patients but were usually mild and self-limited. Elevations above 5 times the upper limit of normal (ULN) occurred in 1% to 9% of patients and generally responded to dose adjustment or temporary discontinuation and restarting at a lower dose, which is recommended if liver test results are markedly elevated (ALT or AST persistently greater than 5 times ULN or bilirubin more than 3 times ULN). While episodes of marked serum aminotransferase elevations with symptoms have been reported, there have been no published reports of clinically apparent liver injury with jaundice attributed to dasatinib therapy.
- Withhold Gleevec if elevations in bilirubin more than 3 times the upper limit of normal (ULN) or transaminases more than 5 times the ULN occur. May be restarted at a lower dosage once bilirubin falls to less than 1.5 times ULN or transaminases fall to less than 2.5 times ULN.
- May also cause growth retardation in children and adolescents and growth should be monitored.
- Tumor lysis syndrome has been reported in people receiving Gleevec. Those at higher risk include people with tumors that have a high proliferative rate or high tumor burden before treatment. Correct dehydration and treat high uric acid levels prior to Gleevec initiation.
- May affect the heart and cause heart failure or left ventricular dysfunction, and other adverse effects including numbness or tingling in the hands or feet.
- Requires ongoing blood monitoring every 2 to 3 months. Gleevec treatment may be associated with anemia, neutropenia, and thrombocytopenia.
- May cause hepatitis B reactivation. Ensure a person's vaccination status is up to date before administering Gleevec. Do not administer any live vaccines during treatment.
- Gleevec may harm a developing fetus and should not be given to pregnant women. Females of reproductive potential should use effective contraception during treatment with Gleevec and for at least 14 days after the last dose. Breastfeeding is not advised.
Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects
4. Tips
- Take Gleevec with food and a large glass of water. Talk to your doctor if you develop dyspepsia or abdominal pain after taking Gleevec. Do not stop taking Gleevec without talking to your doctor.
- Do not take Gleevec with grapefruit or grapefruit juice or products because this may increase the side effects of Gleevec.
- Swallow Gleevec tablets whole with a glass of water. They should not be chewed, opened, or crushed. Take them at the same time every day. If you find it hard to swallow the tablets or capsules, tell your doctor, nurse, or pharmacist.
- If you miss a dose of Gleevec, take it as soon as you remember. If a full day has gone by, let your doctor or nurse know. If you vomit just after taking the capsules or tablets, contact the hospital. Do not take a double dose unless your doctor tells you to.
- During treatment, you will regularly see a hematologist (a doctor who treats blood cancers) or a cancer doctor, a specialist nurse, or a specialist pharmacist, and have your blood monitored regularly. Keep these appointments.
- Gleevec can increase your risk of developing an infection that may become serious. Contact the hospital straight away on the 24-hour contact number you have been given if your temperature goes over 37.5°C (99.5°F), you suddenly feel unwell, even with a normal temperature, you have symptoms of an infection (fever, pain, difficulty breathing, feeling shivery and shaking, a sore throat, a cough, diarrhea, needing to pee a lot or pain while peeing), or your temperature goes below 36°C (96.8°F).
- Gleevec can make you bruise or bleed more easily. Talk to your doctor if you have any unexplained bruising or bleeding including nosebleeds, bleeding gums, heavy periods, blood in your urine (pee) or stools (poo), or tiny red or purple spots on the skin that may look like a rash.
- Gleevec can also make you anemic. Symptoms include pale skin, lack of energy, feeling breathless, and feeling dizzy, and light-headed. Tell your doctor or nurse if you have these symptoms.
- If Gleevec makes you feel sick or vomit, your doctor can prescribe anti-sickness (anti-emetic) drugs to prevent or reduce sickness and vomiting.
- If you develop diarrhea while taking Gleevec, try to drink at least 2 liters (3½ pints) of fluids each day; avoid alcohol, caffeine, milk products, high-fat foods, and high-fiber foods; and talk to your doctor about medications to help reduce it.
- Tell your doctor if you develop any other side effects of concern, including rapid weight gain. This may indicate fluid build-up. If you have a severe rash or any blistering or peeling contact your doctor immediately.
- Your skin may be more sensitive to the sun while taking Gleevec. Apply sunscreen with an SPF of at least 30 when you are in the sun. Cover up with clothing and a hat.
- If you lose your appetite try to eat smaller meals more often. Talk to a dietician if you find it difficult to eat enough. They can give you advice on getting more calories and protein in your diet and possibly supplement drinks to try or you can buy these from your drugstore.
- Gleevec can cause drowsiness and eye pain, dry or watery eyes, or blurred vision which may affect your ability to drive or operate machinery.
- If you develop a bitter or metallic taste in your mouth, try sucking sugar-free sweets or try different foods to find out what tastes best to you. Taste changes usually get better after treatment finishes.
- Talk to your doctor or pharmacist before taking any other medicines with Gleevec including vitamins, herbal drugs, or complementary therapies.
- All your vaccinations should be up to date before starting Gleevec. While taking Gleevec you will not be allowed to have any live vaccines. Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. If you have had Hepatitis B (a liver infection) in the past, this treatment can make it active again.
- Tell your doctor if you are pregnant, intending to become pregnant, or breastfeeding because Gleevec may not be suitable for you.
5. Response and effectiveness
- In patients with newly diagnosed CML, the estimated rate of progression-free survival at 84 months was 81.2% in the Gleevec arm and 60.6% in the interferon-alpha (IFN) plus cytarabine (Ara-C) arm. With 7 years follow up there were 93 (16.8%) progression events in the Gleevec arm compared to 165 (29.8%) events in the IFN+Ara-C arm of which 130 occurred during first-line treatment with IFN-Ara-C.
- The estimated rate of patients free of progression to accelerated phase (AP) or blast crisis (BC) at 84 months was 92.5% in the Gleevec arm and 85.1% in the IFN arm.
- See the product information for a full list of clinical trials associated with Gleevec.
- Continue treatment for as long as there is no evidence of progressive disease or unacceptable toxicity.
- If one TKI does not work or stops working, consider switching to a different one.
6. Interactions
Medicines that interact with Gleevec may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with Gleevec. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Gleevec interacts with over 630 drugs. Most of these interactions are considered major or moderate. Common medications that may interact with Gleevec include:
- acetaminophen
- aminolevulinic acid
- antiandrogens, such as apalutamide and enzalutamide
- antipsychotics, such as clozapine
- azathioprine
- benzodiazepines, such as alprazolam, oxazepam, or temazepam
- black cohosh, brewer's yeast, or ginseng
- cannabis
- chemotherapy agents such as mitotane
- cisapride
- colchicine
- corticosteroids, such as dexamethasone
- CYP450 2D6 substrates such as amitriptyline, codeine, dextromethorphan, tramadol, venlafaxine
- CYP450 3A4 inducers, such as carbamazepine, fosphenytoin, phenobarbital, phenytoin, and rifampin (may reduce the effectiveness of Gleevec)
- CYP450 3A4 inhibitors, such as clarithromycin, erythromycin, diltiazem, itraconazole, ketoconazole, ritonavir, verapamil, goldenseal, and grapefruit (may increase plasma concentrations of Gleevec)
- CYP450 3A4 substrates such as triazolam, nifedipine, statins, warfarin, etc (may increase blood concentrations of these agents)
- etanercept
- fentanyl, hydrocodone, or oxycodone
- fingolimod
- grapefruit juice
- griseofulvin
- high cholesterol treatments such as simvastatin
- infliximab
- ketoconazole
- live vaccines and some other vaccines, such as BCG, cholera, Covid-19 vaccines, measles, hepatitis b vaccines, yellow fever, or live influenza vaccines (Gleevec reduces the immune response to vaccination. Administer live or live-attenuated vaccines at least 4 weeks before Gleevec initiation, and non-live vaccines at least 2 weeks before)
- NSAIDs such as diclofenac or ibuprofen
- rifampin or rifabutin
- SSRIs such as fluoxetine, paroxetine, or sertraline
- St. John's Wort
- targeted treatments such as brigatinib and dabrafenib
- TNF inhibitors such as adalimumab
- warfarin
- zolpidem.
Note that this list is not all-inclusive and includes only common medications that may interact with Gleevec. You should refer to the prescribing information for Gleevec for a complete list of interactions.