Dosage of Vemurafenib

1. Patient Selection for Treatment of Melanoma

Confirm the presence of BRAF V600E mutation in melanoma tumor specimens prior to initiation of treatment with Vemurafenib.

2. Recommended Dose

The recommended dose of Vemurafenib is 960 mg (four 240 mg tablets) orally every 12 hours with or without a meal. A missed dose can be taken up to 4 hours prior to the next dose.

Treat patients with Vemurafenib until disease progression or unacceptable toxicity occurs.

Do not take an additional dose if vomiting occurs after Vemurafenib administration, but continue with the next scheduled dose. Do not crush or chew the tablets.

3. Dose Modifications

For New Primary Cutaneous Malignancies: No dose modifications are recommended.

For Other Adverse Reactions: Permanently discontinue Vemurafenib for any of the following:

• Grade 4 adverse reaction, first appearance (if clinically appropriate) or second appearance

• QTc prolongation > 500 ms and increased by > 60 ms from pre-treatment values

Withhold Vemurafenib for NCI-CTCAE (v4.0) intolerable Grade 2 or greater adverse reactions.

Upon recovery to Grade 0–1, restart Vemurafenib at a reduced dose as follows:

• 720 mg twice daily for first appearance of intolerable Grade 2 or Grade 3 adverse reactions

• 480 mg twice daily for second appearance of Grade 2 (if intolerable) or Grade 3 adverse reactions or  for first appearance of Grade 4 adverse reaction (if clinically appropriate)

Do not dose reduce to below 480 mg twice daily.

4. Dose Modification for Strong CYP3A4 Inducers

Avoid concomitant use of strong CYP3A4 inducers during treatment with Vemurafenib. If concomitant use of a strong CYP3A4 inducer is unavoidable, increase the dose of Vemurafenib by 240 mg (one tablet) as tolerated. After discontinuation of a strong CYP3A4 inducer for two weeks, resume the Vemurafenib dose that was taken prior to initiating the  strong CYP3A4 inducer.

from FDA，2020.12