cobimetinib hemifumarate at a glance
Medicine class
MEK1 and MEK2 inhibitor
Licensed role
Used with vemurafenib for unresectable or metastatic BRAF V600 mutation-positive melanoma in adults
Administration
Swallow the film-coated tablets whole with water, with or without food
Important avoidance
Avoid grapefruit juice because it can increase cobimetinib exposure
What is cobimetinib hemifumarate used for?
UK-licensed use:
With vemurafenib for adults with unresectable or metastatic melanoma confirmed by a validated test to carry a BRAF V600 mutation.
How does cobimetinib hemifumarate work?
Cobimetinib inhibits MEK1 and MEK2, reducing MAPK pathway signalling that promotes cell division. Vemurafenib targets mutated BRAF earlier in the same pathway.
cobimetinib hemifumarate preparations and strengths
Tablet
Route: Oral
Strengths: 20 mg
How to take cobimetinib hemifumarate
Follow the treatment plan supplied by the oncology team.
Swallow tablets whole with water.
They may be taken with or without food.
Avoid grapefruit juice.
Do not drive or operate machinery if sight changes, dizziness, tiredness or other effects make this unsafe.
cobimetinib hemifumarate side effects
Common or expected effects
- Diarrhoea, nausea or vomiting
- Rash, dry or itchy skin and increased sensitivity to sunlight
- Fever or chills
- Blurred vision or serous retinopathy
- High blood pressure, anaemia or bleeding
- Raised liver enzymes or creatine phosphokinase
- Sore mouth
- Peripheral swelling
Get urgent medical advice
- Severe or unusual bleeding
- New or worsening visual disturbance
- Reduced heart pumping function, with breathlessness, palpitations or leg swelling
- Muscle breakdown, suggested by severe muscle symptoms or dark urine
- Severe diarrhoea and dehydration
- Pneumonitis causing new or worsening breathing difficulty
- Significant liver injury, which may cause yellow skin or eyes
cobimetinib hemifumarate in pregnancy
Cobimetinib should generally be avoided during pregnancy because animal studies found embryo loss and fetal malformations, and human data are lacking. Discuss pregnancy or pregnancy plans promptly with the specialist team. Women who could become pregnant should use two effective contraceptive methods during treatment and for at least three months afterwards.
cobimetinib hemifumarate while breastfeeding
It is unknown whether cobimetinib enters human milk, and risk to a breastfed child cannot be excluded. Specialists should weigh stopping breastfeeding against stopping treatment.
cobimetinib hemifumarate interactions
A full medicines and supplements review is needed before and during treatment.
Strong CYP3A inhibitors, including clarithromycin, itraconazole, voriconazole, posaconazole, ritonavir and cobicistat
Can substantially increase cobimetinib exposure and should generally be avoided.
Moderate CYP3A inhibitors, including erythromycin, fluconazole, diltiazem, verapamil and amiodarone
May increase exposure, requiring caution and closer toxicity monitoring.
CYP3A inducers, including rifampicin, carbamazepine, phenytoin and St John’s wort
May reduce exposure and compromise effectiveness, so concurrent use should be avoided.
Common questions about cobimetinib hemifumarate
Answers are fully visible for fast scanning and source review.
Why is cobimetinib hemifumarate combined with vemurafenib?
They inhibit different points in the BRAF–MEK–ERK growth pathway in BRAF V600 mutation-positive melanoma.
Why is a BRAF test needed?
Its licensed melanoma use is restricted to tumours with a confirmed BRAF V600 mutation.
Can it be taken with food?
Yes. Swallow the tablets whole with water, with or without food.
Can I drink grapefruit juice?
No. Grapefruit juice can increase cobimetinib exposure and the likelihood of adverse effects.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.