Melanoma Brain Metastases and Immunotherapy — What Actually Reaches the Brain

Fewer people than expect to be, and almost nobody on the day the scan is reported. Immunotherapy is considered once the brain is stable: deposits that are small or causing no symptoms, no dangerous swelling, and no need for a high steroid dose. A large deposit, a bleed, or seizures must be dealt with first.

The steroid dose is the single item that decides most of these conversations. Immunotherapy works by releasing the brakes on immune cells. Steroids suppress those same cells. A patient on a high ongoing dose is being given a treatment and its opposite at once. This is rarely a permanent exclusion. It is usually a sequencing problem, and it is solved by treating the deposit locally so the steroid can be tapered.

Size, number and position decide whether local treatment is needed first. A deposit pressing on something important, one that has bled, or one causing fits needs radiation or, occasionally, an operation before anything systemic starts. A neurosurgical opinion is coordinated where a lesion may need removing.

Fitness and immune history apply here exactly as they do for any checkpoint inhibitor. Active autoimmune disease, a transplanted organ, or ongoing immune-suppressing treatment are barriers. So is frailty with poor organ reserve, because the question is not only whether you would respond, but whether a serious immune reaction could be survived if one happened.

Then there is subtype, and this is where Indian patients are most often misled. Most published melanoma data describes sun-exposure-driven melanoma. In India, melanoma much more often starts on the sole of the foot, on the palm, under a nail, or on an internal lining such as the mouth or nose. Guideline bodies report lower response for those subtypes. The toxicity does not fall with them.

Nothing on this page decides eligibility. That rests on the brain MRI, the biopsy report, the current steroid dose, previous treatment and overall fitness, read together by a medical oncologist, a radiation oncologist and a tumour board.

Yes, in a proportion of carefully selected patients. The old assumption that the blood-brain barrier keeps immune treatment out has not held up. NCCN and ESMO guidance summaries, as of August 2026, report measurable shrinkage of brain deposits in roughly half of selected patients given two checkpoint drugs together, and in roughly one in five to one in four given a single drug.

The reason the barrier argument failed is worth understanding, because it is still repeated. Immunotherapy does not have to reach the deposit itself. It acts on immune cells, releasing the brakes that hold them back. It is the immune cell, not the medicine, that then travels into brain tissue and does the work. Once activated, those cells cross where an untargeted drug molecule would not.

Two pathways are involved when both drugs are used. One acts on the PD-1 pathway, which restrains immune cells at the point where they meet the tumour. The other acts on the CTLA-4 pathway, earlier, where immune cells are first switched on in the lymph nodes. Releasing both is reported to produce more activity inside the skull than releasing one, and also considerably more toxicity.

Read the figures with their fence around them. They describe trial populations of patients whose brain deposits were small, causing no symptoms, not previously treated, and who were not taking steroids. They are objective-response figures, meaning measurable shrinkage on a scan. They are not survival figures, and they are not a prediction for one person.

Where it does work, the response can be long. Oncologists deliberately use the phrase durable response and stop there, because the same long follow-up that documents responses lasting years also documents late relapses. That is the honest version of the good news, and it is still genuinely good news: two decades ago there was very little to offer here at all.

One practical point that surprises families. The brain and the rest of the body do not always move together. A deposit in the brain can grow while disease elsewhere is shrinking, or the reverse. That is why the brain is scanned on its own schedule with its own MRI, and not assumed to be following the body scan. See Immunotherapy for Melanoma for how the treatment is used across the rest of the disease.

Usually yes, because the two do different jobs. Stereotactic radiosurgery acts on one or a few named deposits within days, which is what controls pressure and symptoms. Immunotherapy acts over weeks to months, across the whole body, including deposits nobody has scanned yet. Most plans use both rather than choosing between them.

Read the table down the first column. Each option answers a different question, and the plan is built from which questions actually need answering in this case.

Whole-brain radiotherapy is used far more selectively than it once was. It treats deposits that cannot yet be seen, which is a real advantage, but the effect on memory and concentration is well documented, and radiosurgery has taken over wherever the number of deposits allows it. Ask directly which of the two is being proposed and why.

There is an unsettled question about giving radiosurgery and immunotherapy close together. Some evidence suggests the combination may work better than either alone, because radiation exposes tumour material the immune system can then recognise. The same closeness is also associated with more swelling and more radiation change on later scans. The evidence is not settled, so the timing is a judgement made case by case.

Radiation planning is done with a radiation oncologist as part of the same tumour-board discussion, and stereotactic radiosurgery is delivered at a unit equipped for the technique. Immunotherapy itself is given as day care at CION centres.

Anything new in the head, and anything new in the bowel, chest, eyes or skin. Two separate things can go wrong on this treatment: the brain deposits themselves, and an immune reaction elsewhere. Both move faster than families expect. Call the treating team or the CION helpline on 1800 202 8726 the same day.

Tell every doctor you see, for any reason, that you are on immunotherapy. An immune reaction in the bowel, the lungs or the heart is easily mistaken for an infection by a clinician who does not know, and the treatment for the two is not the same. A brain symptom is easily put down to stress or tiredness for the same reason.

• How immunotherapy is used across melanoma generally, not only when the brain is involved — Immunotherapy for Melanoma covers stages, eligibility and what a course looks like.
• Not every skin cancer behaves like melanoma. If the diagnosis on the report is squamous or basal cell rather than melanoma, Immunotherapy for Squamous and Basal Cell Skin Cancers is the page that applies.
• For a sense of how differently immunotherapy performs in less common cancers, Immunotherapy for Thyroid and Salivary Gland Cancers sets out where its role is still being defined rather than established.
• And for the other side of that contrast — a cancer where immunotherapy is not the main answer at all — see Immunotherapy for Testicular Cancer.
• For how immunotherapy is delivered, monitored and paid for across our centres, see Immunotherapy at CION Cancer Clinics.

Unsure how any of this applies to a specific scan report? Book a free consultation and a medical oncologist will go through the MRI and the biopsy report with you.