What are the usage methods and precautions of Vemurafenib/Zorbovo Tablets?

Vemurafenib/zobovo(Vemurafenib) is a highly selective BRAF inhibitor, mainly used to treat patients with unresectable or metastatic melanoma with BRAF V600E mutations. The drug targets and inhibits the abnormally activated MAPK signaling pathway, thereby slowing down the proliferation and spread of cancer cells. To ensure maximum efficacy and reduce risks, it is important to properly understand its usage and precautions.

1. How to use: In terms of medication, the recommended dose of vemurafenib is 960 mg orally every 12 hours, that is, four 240 mg tablets taken each time. It is usually taken once in the morning and once in the evening, with the first dose taken in the morning and the second dose approximately 12 hours later. The medication may be swallowed with or without food and should not be crushed or chewed. Treatment should be continued until significant disease progression or intolerable adverse effects occur. If a dose is missed, it should be taken within 6 hours, otherwise the dose should be skipped to maintain stable blood concentration.

2. Precautions: During the use of vemurafenib, patients need to closely monitor a series of potential adverse reactions and drug-related risks.

1. Skin tumors are one of the more typical adverse events, including squamous cell carcinoma or keratoacanthoma. It is recommended to conduct dermatological examination before treatment and every two months during treatment, and to continue follow-up for 6 months after discontinuation of treatment to detect and treat new skin lesions early.

2. Tumor promoting effect. BRAF inhibitors may abnormally activate the MAPK pathway in BRAF wild-type cells, leading to abnormal proliferation of normal tissue cells. Therefore, the presence of BRAF V600E mutation in the tumor must be confirmed through molecular testing before treatment, otherwise it may accelerate the progression of the disease.

3. Be wary of severe allergic reactions, including systemic rash, hypotension, and drug reactions accompanied by eosinophilia syndrome. Once it occurs, the drug should be stopped immediately and symptomatic treatment should be carried out. Some patients may relapse after restarting vemurafenib, so those with allergies need to carefully assess the risk.

4. In terms of skin, serious reactions such as StevensJohnson syndrome or toxic epidermal necrolysis may also occur. If large areas of blisters or peeling occur, the drug should be discontinued immediately and seek medical attention.

5. In terms of cardiac safety, vemurafenib may cause QT interval prolongation and increase the risk of torsade de pointes. Electrocardiogram (ECG) and electrolyte (potassium, magnesium, calcium) tests are required before treatment, and rechecked after 15 days after the initial treatment, once a month for the first 3 months, and at least once every three months thereafter. If QTc persists for more than 500ms, medication should be stopped immediately.

6.The hepatotoxicity of drugs also deserves attention. Vemurafenib may cause increases in liver enzymes, alkaline phosphatase, and bilirubin, especially when combined with immune checkpoint inhibitors such asIpilimumab is more obvious when used in combination. It is recommended to monitor liver function regularly before and during treatment. If abnormalities occur, they can be managed by reducing the dose or temporarily discontinuing the drug.

7. Photosensitivity reaction is one of the common side effects of vemurafenib, manifesting as skin erythema, burning or blisters. Patients should try to avoid sun exposure and use broad-spectrum sunscreen with SPF≥30 and sun-protective clothing when going out. For those with severe photosensitivity, consider reducing the dosage or adjusting the medication regimen.

8. In terms of eye health, drugs may cause symptoms such as uveitis, blurred vision, and photophobia. If you experience eye pain or vision loss, you should see an ophthalmologist promptly. Doctors can use corticosteroid eye drops or mydriasis to control it.

9. In addition, vemurafenib has embryo-fetotoxicity and is contraindicated during pregnancy. Women of childbearing age need to take effective contraceptive measures during treatment and for at least two weeks after stopping the drug to prevent fetal malformations.

10. Some patients reported acute kidney injury during treatment, such as acute interstitial nephritis or renal tubular necrosis. It is recommended to monitor serum creatinine before starting treatment and regularly during treatment to identify renal function abnormalities early.

Reference: https://www.drugs.com/mtm/vemurafenib.html