Immunotherapy for Skin Cancer: What Checkpoint Inhibitors Do and What to Expect

What Is Immunotherapy for Skin Cancer?

Your immune system is designed to find and destroy abnormal cells, including cancer cells. But cancer is clever—it learns to hide from immune attack by sending chemical signals that tell your immune cells to stand down. Checkpoint inhibitors are drugs that block those “stand down” signals, freeing your immune cells to recognize and kill the cancer.

These drugs have changed what is possible for patients with advanced melanoma. Before checkpoint inhibitors, the average survival for metastatic melanoma was less than a year. Now, some patients achieve complete remission that lasts for years—even after stopping treatment.

How the Immune System Gets Turned Off (and How We Turn It Back On)

Think of the immune system like a car with both a gas pedal and a brake. When cancer is present, it essentially applies the brakes on the immune cells that would otherwise attack it. It does this through two main systems:

• PD-1/PD-L1 checkpoint: Cancer cells produce a protein called PD-L1 that binds to a “brake receptor” (PD-1) on your immune cells, telling them to stop attacking. Pembrolizumab (Keytruda) and nivolumab (Opdivo) block this interaction, releasing the brake within tumors.
• CTLA-4 checkpoint: CTLA-4 is a brake receptor that slows down immune cells before they even reach the tumor. Ipilimumab (Yervoy) blocks this earlier brake, helping your immune cells get activated and travel to the tumor in the first place.

Using both types of drugs together—combination therapy—works on both brakes simultaneously. This produces higher response rates but also more side effects.

Which Drugs Are Used and How Are They Given?

All checkpoint inhibitors are given by intravenous (IV) infusion at a cancer center or infusion clinic. Typical schedules are:

• Pembrolizumab (Keytruda): 200 mg every 3 weeks, or 400 mg every 6 weeks
• Nivolumab (Opdivo): 240 mg every 2 weeks, or 480 mg every 4 weeks
• Ipilimumab (Yervoy): 3 mg/kg every 3 weeks for 4 doses (then less frequently)
• Combination (nivolumab + ipilimumab): Nivolumab 1 mg/kg + ipilimumab 3 mg/kg, given together every 3 weeks for 4 doses, then nivolumab alone

Infusions typically take 30–90 minutes. You will usually be monitored for a short period afterward before going home.

How Well Does Immunotherapy Work?

For Metastatic Melanoma

• PD-1 inhibitor alone (pembrolizumab or nivolumab): Response rates of 30–40%. Complete remission in 5–10% of patients. Median overall survival of 15–18 months.
• Combination (nivolumab + ipilimumab): Response rates of 50–60%. Complete remission in 10–15%. Median overall survival of 25–37 months. However, side effects are significantly more common.
• Ipilimumab alone: Lower response rates (10–15%) and now rarely used as the primary option given better alternatives.

For Early-Stage Melanoma (Adjuvant Therapy)

If you had surgery for Stage III melanoma (meaning the cancer reached your lymph nodes), you may be offered immunotherapy afterward to reduce the risk of the cancer coming back. Both nivolumab and pembrolizumab have been shown to improve recurrence-free survival. Adjuvant nivolumab is given for 12 months; adjuvant ipilimumab is given for up to 3 years.

For Other Skin Cancers

Immunotherapy is also approved for advanced squamous cell carcinoma (cemiplimab and pembrolizumab) and Merkel cell carcinoma (avelumab and pembrolizumab). Research is ongoing for other skin cancers.

Side Effects: Immune-Related Adverse Events (irAEs)

Because checkpoint inhibitors boost your immune system broadly, they can sometimes cause it to attack healthy tissues. These are called immune-related adverse events (irAEs). They are different from traditional chemotherapy side effects and can affect almost any organ.

Common Side Effects

• Skin reactions (20–30% of patients): Rash, itching, and a patchy loss of pigment (vitiligo, which is usually benign and may actually signal a good response to treatment)
• Fatigue: Very common, especially in the first few weeks of treatment
• Diarrhea and colitis (20–30%): Loose stools are common; severe colitis (bloody diarrhea with cramping) requires stopping the drug and starting steroids
• Thyroid problems (10–20%): Both overactive and underactive thyroid can develop. This is usually manageable with thyroid medication and does not necessarily require stopping immunotherapy

Less Common but Serious Side Effects

• Pneumonitis (lung inflammation): Shortness of breath or new cough should be reported immediately
• Hepatitis (liver inflammation): Detected by routine blood tests; usually treated with steroids
• Adrenal insufficiency or hypophysitis (pituitary problems): Can cause severe fatigue, low blood pressure, or hormonal disturbances—requires immediate evaluation

With combination therapy (nivolumab + ipilimumab), severe side effects occur in about 55–60% of patients, compared to about 25% with a single drug. This is the main trade-off to discuss with your doctor when choosing between single-agent and combination treatment.

Managing Side Effects

Most irAEs respond well to treatment with corticosteroids (such as prednisone). Mild reactions may only need monitoring or topical treatments. Severe reactions typically require pausing or stopping immunotherapy and starting steroids at 1–2 mg/kg daily, tapered over several weeks. Most side effects fully resolve with appropriate management, though some (like thyroid disease) may be permanent.

Report any new symptoms to your oncology team promptly—early intervention prevents most serious complications.

Will Immunotherapy Work for You? Predictors of Response

Researchers have identified factors that predict who is more likely to respond:

• PD-L1 expression: Tumors that test positive for PD-L1 show higher response rates (40–50%) compared with PD-L1-negative tumors (20–30%), but about 30–40% of PD-L1-negative patients still respond—so a negative result does not mean the drug will not work
• Tumor mutational burden (TMB): Tumors with many genetic mutations are often more recognizable to immune cells. High-TMB tumors have response rates of 50–60%
• BRAF mutation status: If your tumor has a BRAF mutation, your doctor may also consider targeted therapy (BRAF/MEK inhibitors) as an alternative or sequential treatment

When to See a Dermatologist or Oncologist

• You have been diagnosed with Stage III or Stage IV melanoma and have not yet discussed immunotherapy options
• You develop a new rash, skin blistering, or significant pigment changes during immunotherapy
• Any new symptom that develops during treatment, including shortness of breath, diarrhea, eye redness, or joint pain—these could be irAEs needing prompt attention
• You are uncertain whether you are a candidate for immunotherapy based on your stage or tumor type

Frequently Asked Questions

How long will I need to take immunotherapy?

For metastatic melanoma, treatment continues until the cancer stops responding, you experience unacceptable side effects, or you achieve a complete remission and you and your doctor agree to stop. Some patients remain in remission long after stopping treatment. For adjuvant therapy after surgery, the treatment period is fixed: 12 months for nivolumab, up to 3 years for ipilimumab.

Is combination immunotherapy always better than a single drug?

Combination therapy produces higher response rates and better long-term survival for metastatic melanoma, but it also causes significantly more side effects. Whether the extra benefit outweighs the additional risk depends on your overall health, how rapidly your disease is progressing, and your personal preferences. Your oncologist will walk you through the trade-offs for your specific situation.

Can immunotherapy be used if I have an autoimmune disease?

Active, serious autoimmune conditions (like severe rheumatoid arthritis, lupus, or inflammatory bowel disease) increase the risk of severe irAEs. However, many patients with autoimmune conditions can still receive immunotherapy with careful monitoring and pre-treatment precautions. Discuss your full medical history with your oncologist before starting treatment.

What if I develop a rash during immunotherapy?

Mild rashes are common and do not always require stopping the drug. Report any rash to your care team immediately so it can be graded. Mild rashes may be treated with topical steroids. Severe blistering rashes (like Stevens-Johnson syndrome, though rare) require immediate discontinuation of therapy and urgent care. Do not try to self-treat a rash that develops during immunotherapy—always get it evaluated first.

References

Trusted Resources

• American Academy of Dermatology: Melanoma Treatment
• Skin Cancer Foundation: Melanoma Treatments
• National Cancer Institute: Checkpoint Inhibitors
• Mayo Clinic: Immunotherapy

Always consult a board-certified dermatologist or oncologist for personalized treatment recommendations. This article is for educational purposes and does not replace individualized medical advice.