Immunotherapy for Skin Cancer: How Checkpoint Inhibitors Work and What to Expect

The Bottom Line

Immunotherapy has completely changed the landscape for people with advanced melanoma and other skin cancers. These drugs work by releasing your immune system's natural brakes so your own T cells can attack the cancer. About 40-50% of patients respond to single-agent immunotherapy, and combining two agents raises that to over 60%. For patients who respond, some have had remissions lasting years. Side effects are real and require monitoring, but most are manageable with prompt treatment.

What Is Immunotherapy for Skin Cancer?

Immunotherapy is a type of cancer treatment that works with your body's own immune system rather than directly killing cancer cells with toxic drugs. The most effective immunotherapy drugs for skin cancer are called checkpoint inhibitors—a name that refers to how they work.

Your immune system has built-in “checkpoints”—proteins on immune cells that normally act like brakes to prevent the immune system from attacking your own healthy tissue. Cancer cells exploit this system by activating these brakes, essentially hiding from your immune system. Checkpoint inhibitor drugs block those brakes, freeing your T cells (the immune cells that fight cancer) to recognize and destroy the tumor.

Melanoma responds particularly well to immunotherapy because it tends to be highly immunogenic—meaning it has many mutations that make it recognizable to the immune system once the brakes are released.

The Main Immunotherapy Drugs for Skin Cancer

PD-1 Inhibitors (the most commonly used)

PD-1 (programmed death-1) is a protein on T cells that acts as a major checkpoint brake. Two FDA-approved PD-1 inhibitors are used for melanoma:

  • Pembrolizumab (Keytruda): Given as an intravenous (IV) infusion every 3 weeks. Response rate in metastatic melanoma: 40-50% as a single agent.
  • Nivolumab (Opdivo): Given as an IV infusion every 2 weeks. Similar response rates to pembrolizumab.

CTLA-4 Inhibitor

CTLA-4 is a different checkpoint protein active earlier in the immune response. The approved drug is:

  • Ipilimumab (Yervoy): Response rate as a single agent: 20-30%. More commonly used in combination with nivolumab.

Combination Immunotherapy

Combining nivolumab and ipilimumab targets two different checkpoints at the same time. This combination achieves response rates over 60% in metastatic melanoma, with median overall survival exceeding 60 months in patients who respond (CheckMate 067 trial). However, it also comes with higher rates of side effects compared to single-agent therapy.

Who Is Immunotherapy Recommended For?

Immunotherapy is considered for:

  • Metastatic melanoma (Stage IV): Cancer that has spread to distant organs, lymph nodes, or skin. Pembrolizumab or nivolumab are standard first-line treatments for patients without BRAF mutations. Combination nivolumab plus ipilimumab is also a first-line option depending on individual factors.
  • Stage III melanoma (after surgery): If your sentinel lymph node was positive, adjuvant (preventive) immunotherapy with pembrolizumab or nivolumab is recommended to reduce recurrence risk by 25-30%.
  • BRAF-mutant melanoma: If your tumor has a BRAF V600E mutation (present in about 60% of melanomas), your oncologist will discuss whether targeted therapy (dabrafenib plus trametinib) or immunotherapy—or both in sequence—is the better first approach.

How Well Does It Work?

The response rates and survival data for checkpoint inhibitors represent one of the most dramatic advances in cancer medicine in decades:

  • Single-agent pembrolizumab or nivolumab: ~40-50% of patients respond
  • Combination nivolumab + ipilimumab: over 60% of patients respond
  • Among responding patients treated with combination therapy: median overall survival exceeds 60 months (5+ years)
  • Some patients achieve durable complete responses—meaning all visible cancer disappears—and remain in remission for years

Patients whose tumors have higher numbers of mutations (called high tumor mutational burden), or whose tumors express more PD-L1 (the protein that activates the PD-1 brake), tend to respond better. However, PD-L1 status is not reliable enough to withhold treatment from patients who test negative—some PD-L1-negative patients still respond well.

What to Expect During Treatment

Immunotherapy is given as an IV infusion in an outpatient oncology clinic. Each session typically takes 30-60 minutes. You will not feel the drug entering your body during the infusion. Afterward, most patients go home the same day.

Treatment schedules vary:

  • Pembrolizumab: every 3 weeks, or every 6 weeks at a higher dose
  • Nivolumab: every 2 or 4 weeks
  • Combination therapy: an intensive schedule during the first few months, then maintenance

Response is assessed with CT scans (and brain MRI when indicated) every 8-12 weeks to see how the tumor is responding. LDH blood levels (a marker of tumor burden) are also tracked.

Side Effects: Immune-Related Adverse Events

Because checkpoint inhibitors release the brakes on your whole immune system, they can cause inflammation in healthy organs too. These are called immune-related adverse events (irAEs). They affect 50-90% of patients to some degree and can involve virtually any organ:

  • Skin: Rash, itching (very common, often manageable with topical steroids)
  • Gut: Diarrhea or colitis (inflammation of the colon)
  • Liver: Elevated liver enzymes (hepatitis), usually caught by routine blood tests
  • Lungs: Pneumonitis (lung inflammation)—rare but serious
  • Thyroid: Hypothyroidism or hyperthyroidism (very common with combination therapy)
  • Joints: Arthritis-like pain

Most side effects are Grade 1-2 (mild to moderate) and resolve with treatment. Serious Grade 3-4 events requiring hospitalization or high-dose steroids occur in 20-30% of patients on combination therapy and about 10-15% on single-agent therapy. Your oncology team will monitor you closely and has clear protocols for managing these events.

When to See Your Doctor Urgently During Treatment

Call your oncology team right away if you develop:

  • Severe diarrhea or blood in your stool
  • Shortness of breath or a new cough
  • Significant skin rash or blistering
  • Yellow skin or eyes (jaundice)
  • Severe headache or vision changes
  • Weakness or fatigue that is significantly worse than usual

Immune-related side effects caught early are much easier to manage than those that have progressed. Always err on the side of reporting symptoms promptly.

When to See a Dermatologist or Oncologist

  • You have been diagnosed with Stage III or Stage IV melanoma
  • You want to understand your immunotherapy options before starting treatment
  • You are currently on immunotherapy and are experiencing a new rash or other symptoms
  • You have a BRAF mutation and want to understand whether targeted therapy or immunotherapy is right for you first
  • You are concerned about long-term management after completing immunotherapy

Frequently Asked Questions

Is immunotherapy the same as chemotherapy?

No, they work very differently. Chemotherapy kills rapidly dividing cells throughout the body, which is why it causes hair loss, nausea, and bone marrow suppression. Immunotherapy does not directly attack cancer cells—it activates your immune system to do the work. Side effects are different too: instead of the classic chemotherapy side effects, immunotherapy causes immune-related inflammation that can affect different organs. Many patients tolerate immunotherapy better than traditional chemotherapy.

Can I have immunotherapy if I have an autoimmune disease?

Active autoimmune disease is a relative contraindication, not an absolute one. If your immune system is already overactive (as in lupus, rheumatoid arthritis, or inflammatory bowel disease), checkpoint inhibitors could make it worse. Your oncologist will weigh the risks carefully. Some patients with autoimmune disease have been successfully treated with immunotherapy under close monitoring. This decision requires a thorough individual discussion with your care team.

What happens if immunotherapy stops working?

If your cancer progresses despite immunotherapy, several options remain. If you have a BRAF mutation, targeted therapy (BRAF + MEK inhibitors) is a powerful next option. Clinical trials investigating new combinations and approaches are another avenue. Some patients are also candidates for switching from one checkpoint inhibitor to another, or adding a second agent. Your oncologist will reassess and build a new treatment plan based on your updated tumor profile.

How long do I stay on immunotherapy?

Treatment duration varies. For adjuvant therapy (preventing recurrence after surgery), standard courses are about 1 year. For metastatic disease, treatment continues as long as you are responding and tolerating the drug. Some oncologists discontinue therapy in patients who achieve a complete response and monitor closely. Duration recommendations continue to evolve as more long-term data becomes available.

References

  1. Larkin J, Chiarion-Sileni V, Gonzalez R, et al. Combined nivolumab and ipilimumab or monotherapy in untreated melanoma. N Engl J Med. 2015;373(1):23-34.
  2. Robert C, Schachter J, Long GV, et al. Pembrolizumab versus ipilimumab in advanced melanoma (KEYNOTE-006). N Engl J Med. 2015;372(26):2521-2532.
  3. Weber JS, Mandala M, Del Vecchio M, et al. Adjuvant nivolumab versus ipilimumab in resected Stage III or IV melanoma (CheckMate 238). N Engl J Med. 2017;377(19):1824-1835.
  4. Eggermont AM, Blank CU, Mandala M, et al. Adjuvant pembrolizumab versus placebo in resected stage III melanoma (KEYNOTE-054). N Engl J Med. 2018;378(19):1789-1801.
  5. Brahmer JR, Lacchetti C, Schneider BJ, et al. Management of immune-related adverse events in patients treated with immune checkpoint inhibitor therapy. J Clin Oncol. 2018;36(17):1714-1768.
  6. Topalian SL, Hodi FS, Brahmer JR, et al. Safety, activity, and immune correlates of anti-PD-1 antibody in cancer. N Engl J Med. 2012;366(26):2443-2454.

Trusted Resources

Always consult a board-certified dermatologist or oncologist for personalized advice about immunotherapy options for your specific diagnosis.