Gavreto is an oral medication that must be taken exactly as prescribed by a healthcare provider.
- Dosage: The recommended dosage for adults is typically 400 mg orally once daily. For pediatric patients 12 years and older with thyroid cancer, the dosage is also 400 mg once daily.
- Administration:
- Gavreto capsules should be swallowed whole with a glass of water.
- It must be taken on an empty stomach. This means no food intake for at least 2 hours before and at least 1 hour after taking Gavreto.
- Do not open, chew, or crush the capsules.
- Missed Dose: If a dose is missed, it can be taken as soon as possible on the same day, unless the next scheduled dose is due within 12 hours. In that case, the missed dose should be skipped, and the regular daily schedule should be resumed the next day.
- Vomiting: If vomiting occurs after taking a dose, do not take an additional dose. Continue with the next scheduled dose.
- Duration of Treatment: Treatment with Gavreto is typically continued until disease progression or until unacceptable toxicity occurs.
- Dose Modifications: The healthcare provider may adjust the dose of Gavreto (interrupt, reduce, or discontinue) based on the patient’s tolerance to side effects or in response to drug interactions.
Strict adherence to the prescribed dosage and administration instructions is crucial for the effectiveness and safety of Gavreto treatment.
Gavreto’s mechanism of action centers on its role as a highly selective tyrosine kinase inhibitor (TKI). The RET gene encodes for a receptor tyrosine kinase, a type of protein that plays a crucial role in cell signaling, growth, and differentiation. In certain cancers, genetic alterations (fusions or mutations) lead to abnormal, constitutively active RET proteins. These abnormal RET proteins continuously signal, driving uncontrolled cell proliferation and tumor growth.
Pralsetinib, the active ingredient in Gavreto, works by:
- Selectively Inhibiting RET: It binds to and inhibits the kinase activity of both wild-type RET and various RET fusions and mutations (including common resistance mutations). By blocking this aberrant signaling pathway, Gavreto effectively halts the uncontrolled growth and survival of cancer cells that rely on these RET alterations.
- Targeted Therapy: This highly selective inhibition means that Gavreto primarily targets the cancer cells with the specific RET alterations, potentially sparing healthy cells and leading to a more favorable side effect profile compared to less selective treatments.
The precise targeting of the RET pathway helps to shrink tumors and control disease progression in p
While Gavreto is a targeted therapy, it can still cause a range of side effects, some of which can be serious or life-threatening. Patients receiving Gavreto require close monitoring for these adverse reactions.
- Common Side Effects (≥25%):
- Musculoskeletal pain (muscle and joint pain)
- Constipation
- Diarrhea
- Fatigue (tiredness)
- Edema (swelling of face, arms, legs, hands, and feet)
- Hypertension (high blood pressure)
- Pyrexia (fever)
- Cough
- Common Abnormal Blood Test Results: Decreased white blood cell counts (lymphocytes, neutrophils), decreased red blood cell counts (hemoglobin), decreased platelet counts, decreased phosphate, sodium, and calcium levels, increased liver enzymes (AST, ALT), and increased alkaline phosphatase.
- Serious Side Effects (requires immediate medical attention):
- Interstitial Lung Disease (ILD)/Pneumonitis: Severe, life-threatening inflammation of the lungs, which can be fatal. Symptoms include new or worsening shortness of breath, cough, and fever.
- Hypertension: High blood pressure is common and can be severe. Blood pressure needs to be monitored regularly.
- Hepatotoxicity (Liver Problems): Serious liver problems, including liver damage, can occur. Liver function tests (AST, ALT) should be monitored. Symptoms include yellowing of skin/eyes (jaundice), dark urine, nausea, vomiting, or pain in the upper right stomach area.
- Hemorrhagic Events (Bleeding Problems): Serious, including fatal, bleeding can occur. Symptoms include vomiting blood, blood in urine/stools, coughing up blood, unusual bruising, or heavy menstrual bleeding.
- Tumor Lysis Syndrome (TLS): Caused by the rapid breakdown of cancer cells, leading to electrolyte imbalances. Symptoms include nausea, vomiting, weakness, swelling, shortness of breath, muscle cramps, and seizures.
- Risk of Impaired Wound Healing: Can occur in patients receiving drugs that inhibit the VEGF signaling pathway.
Patients should report any new or worsening symptoms to their healthcare provider immediately.
Gavreto carries several important warnings and precautions due to the potential for serious adverse reactions. Close monitoring by a healthcare provider is essential during treatment.
- Interstitial Lung Disease/Pneumonitis: Severe, life-threatening, and fatal cases have been reported. Patients should be monitored for new or worsening respiratory symptoms. Gavreto may need to be withheld, dose-reduced, or permanently discontinued.
- Hypertension: High blood pressure is common and can be severe. Blood pressure should be optimized before starting Gavreto and monitored regularly (after 1 week, then monthly, or as clinically indicated). Antihypertensive therapy may be initiated or adjusted.
- Hepatotoxicity: Serious liver problems can occur. Liver function tests (AST, ALT) should be monitored before and during treatment (every 2 weeks for the first 3 months, then monthly). Dose adjustments or discontinuation may be necessary.
- Hemorrhagic Events: Serious, including fatal, bleeding events have been reported. Patients should be monitored for signs and symptoms of bleeding.
- Tumor Lysis Syndrome (TLS): Cases have been reported, particularly in patients with medullary thyroid carcinoma. Patients should be monitored for signs and symptoms of TLS, especially those with high tumor burden.
- Risk of Impaired Wound Healing: Gavreto can impair wound healing. Temporary interruption of Gavreto may be advised before planned surgical procedures.
- Embryo-Fetal Toxicity: Based on animal studies and its mechanism of action, Gavreto can cause fetal harm. Females of reproductive potential should use effective non-hormonal contraception during treatment and for 2 weeks after the last dose. Males with female partners of reproductive potential should use effective contraception during treatment and for 1 week after the last dose.
- QT Prolongation: Gavreto can cause QT interval prolongation. Patients should be monitored for QT prolongation, especially those with pre-existing cardiac conditions or on medications known to prolong the QT interval.
Gavreto (pralsetinib) can interact with a significant number of other medications, primarily due to its metabolism by certain liver enzymes and its effect on drug transporters. These interactions can alter the levels of Gavreto in the body or affect the levels of co-administered drugs.
- CYP3A Inhibitors: Concomitant use with strong or moderate CYP3A inhibitors (e.g., ketoconazole, clarithromycin, grapefruit juice) can increase Gavreto exposure, potentially leading to increased side effects. Dose adjustments for Gavreto may be necessary.
- CYP3A Inducers: Co-administration with strong or moderate CYP3A inducers (e.g., rifampin, carbamazepine, St. John’s wort) can decrease Gavreto exposure, potentially reducing its efficacy. Dose adjustments for Gavreto may be necessary.
- P-glycoprotein (P-gp) Inhibitors: Gavreto is a substrate of P-gp. Co-administration with P-gp inhibitors can increase Gavreto exposure.
- Acid-Reducing Agents: Medications that reduce gastric acidity (e.g., proton pump inhibitors, H2-receptor antagonists, antacids) may affect the solubility and absorption of Gavreto, potentially reducing its effectiveness. Gavreto should be taken on an empty stomach.
- Substrates of CYP2C8, CYP2C9, CYP3A, and P-gp: Gavreto can influence the metabolism or transport of other drugs that are substrates of these enzymes or transporters, potentially altering their concentrations. Careful monitoring and dose adjustments of these co-administered drugs may be required.
Patients should inform their healthcare provider about all prescription, over-the-counter medications, vitamins, and herbal supplements they are taking to manage potential drug interactions effectively.
The dosage of Gavreto (pralsetinib) is precisely defined and must be administered under the supervision of a healthcare professional experienced in the use of anticancer therapies.
- Recommended Starting Dose: The standard recommended starting dose for adult patients with metastatic RET fusion-positive NSCLC, and for adult and pediatric patients 12 years and older with advanced or metastatic RET-mutant MTC or RET fusion-positive thyroid cancer, is 400 mg orally once daily.
- Administration: Gavreto capsules should be swallowed whole with water on an empty stomach. Patients should not eat for at least 2 hours before and at least 1 hour after taking Gavreto.
- Duration of Treatment: Treatment should continue until disease progression or until unacceptable toxicity.
- Dose Modifications: The healthcare provider may implement dose interruptions, reductions, or permanent discontinuation based on the occurrence and severity of adverse reactions.
- First Dose Reduction: Typically to 300 mg once daily.
- Second Dose Reduction: Typically to 200 mg once daily.
- Third Dose Reduction: Typically to 100 mg once daily.
- Permanent discontinuation is recommended if a patient cannot tolerate 100 mg once daily.
- Special Populations: Dose adjustments may be necessary for patients with hepatic impairment or when co-administered with strong CYP3A inhibitors or inducers.
Regular monitoring of blood counts, liver function, blood pressure, and electrolytes is essential throughout treatment.
Gavreto (pralsetinib) is a prescription-only medication. It is a specialized oncology drug and is not available over-the-counter.
Key aspects of its prescription status:
- Specialist Prescription: Gavreto must be prescribed by a healthcare professional experienced in the use of anticancer therapies and in the management of patients with the specific RET-altered cancers for which it is indicated.
- Diagnostic Testing: Before initiating treatment with Gavreto, patients must undergo an FDA-approved diagnostic test to confirm the presence of the specific RET gene fusion (for NSCLC and thyroid cancer) or RET gene mutation (for MTC). This ensures that the therapy is targeted appropriately.
- Close Monitoring: Due to the potential for serious side effects and the complex nature of cancer treatment, patients receiving Gavreto require close medical supervision and regular monitoring of various blood parameters, blood pressure, and symptoms.
- Risk Evaluation and Mitigation Strategy (REMS): In some regions, Gavreto may be subject to a REMS program to ensure that the benefits of the drug outweigh its risks. This might involve specific requirements for prescribers, pharmacies, and patients.
Patients should never attempt to obtain or use Gavreto without a valid prescription and ongoing medical supervision.
