COMBI-d: What the Melanoma Trial Found

One pathway, two brakes

Roughly half of melanomas carry a mutation in a gene called BRAF. The commonest versions are named V600E and V600K. The mutated protein sits in a chain of signals inside the cell — the MAPK pathway — and jams it in the "grow" position.

Drugs that block BRAF shrink these melanomas fast. The trouble is that they stop working. Cancer cells reactivate the same pathway a step further along, at a protein called MEK.

COMBI-d tested the obvious response: block both steps at once, and see whether the benefit lasts longer.

Trial at a glance

Field	Detail
Trial	COMBI-d
Registry number	NCT01584648
Phase	3
Design	Randomized, double-blind, placebo-controlled
Participants	423
Population	Previously untreated, unresectable stage IIIC or stage IV melanoma with BRAF V600E or V600K
Comparison	Dabrafenib 150 mg twice daily plus trametinib 2 mg once daily, vs dabrafenib plus placebo
Main measure	Progression-free survival

Those were the amounts the trial compared. On treatment, the pairing is adjusted person by person, so use your own prescription.

What the trial found

Median progression-free survival — the time before the cancer grew again — was 9.3 months with the two drugs and 8.8 months with dabrafenib alone.

That gap is half a month, and taken on its own it looks trivial. The hazard ratio tells a different story: 0.75, with a 95% confidence interval of 0.57 to 0.99 and p=0.03. A hazard ratio compares risk across the whole follow-up rather than at one point. It says that at any given moment, the risk of the cancer growing or the person dying was about a quarter lower with the combination. The medians happened to sit close together on a pair of curves that separate later.

Tumors shrank in 67% of the combination group against 51% on dabrafenib alone, with p=0.002.

An early look at survival favored the combination too: 93% of the combination group were alive at six months against 85%, with a hazard ratio for death of 0.63 and p=0.02. That did not cross the trial's prespecified stopping threshold of two-sided p=0.00028, so it was not treated as settled at that point.

The side effect nobody predicted

Adding a second drug usually adds toxicity. Here the overall rates were similar, and one problem actually fell: cutaneous squamous cell carcinoma, a second skin cancer that BRAF inhibitors provoke, occurred in 2% of the combination group against 9% on dabrafenib alone. Blocking MEK appears to prevent the pathway reactivation that causes those growths.

One side effect went sharply the other way. Fever, called pyrexia, occurred in 51% of the combination group against 28%, and was severe in 6% against 2%. It is common enough that teams plan for it from the first dose.

When to get checked

Melanoma is one of the few cancers you can see. The checklist most clinics use is ABCDE — a mole or spot worth showing a doctor if it is:

• Asymmetrical, so one half does not match the other.
• Border irregular, notched, or blurred.
• Color uneven, or containing more than one shade of brown, black, red, white, or blue.
• Diameter larger than about 6 mm, roughly the width of a pencil eraser — though smaller melanomas exist.
• Evolving: changing in size, shape, color, or feel over weeks to months.

Add three more that get missed: a spot that itches, bleeds, or crusts without being knocked; a dark streak appearing under a fingernail or toenail; and any mole that simply looks different from all your others.

Melanoma also occurs on skin that never sees the sun, and on the palms, soles, and nail beds, particularly in people with darker skin. Our overview of melanoma covers the types.

Where this fits now

American Cancer Society projections, published on the SEER site, give about 112,000 new melanomas of the skin in the United States in 2026 and about 8,510 deaths. About 77% are found while still confined to the original site, and five-year relative survival for that group matches the general population. It is 76.0% once the melanoma has reached nearby lymph nodes and 34.0% once it has spread to distant sites. Across all stages it is 94.7%. Those survival figures come from people diagnosed between 2016 and 2022.

Those numbers describe a large mixed group diagnosed years ago and cannot be applied to any individual. They also sit oddly against the trial above, because COMBI-d enrolled only people with advanced disease — the small minority represented by that last figure.

What this story cannot tell you

• The absolute difference in median progression-free survival at this first report was about two weeks. The case for the combination rests on the hazard ratio across the whole curve, not on the medians.
• The survival signal was an interim look that did not meet the trial's own statistical bar. Later reports with longer follow-up did go on to show a survival benefit.
• The control arm was dabrafenib alone, which is not used by itself today. The trial cannot tell you how this combination compares with immunotherapy, which is now a central option in advanced melanoma.
• Everybody enrolled had a BRAF V600E or V600K mutation. None of this applies to melanoma without one.
• Participants met specific entry criteria and were well enough to take part, so results may not carry to everyone with advanced melanoma.

Questions worth asking

• Has my melanoma been tested for BRAF, and what did it show?
• How would targeted therapy and immunotherapy compare for my situation?
• What is the plan if I get a fever on treatment, and when should I call?

Our pages on targeted therapy and how a trial compares with standard treatment give the background.

Sources

• N Engl J Med 2014: Combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma (COMBI-d), PMID 25265492 — record retrieved via NCBI eutils
• ClinicalTrials.gov API v2 record for NCT01584648
• NCI PDQ: Melanoma Treatment (Health Professional Version)
• NCI SEER Cancer Stat Facts: Melanoma of the Skin

How this article was prepared

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.

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