Where Merkel cell carcinoma treatment is heading

Merkel cell carcinoma is a rare, aggressive skin cancer, about 3,000 cases a year in the US, usually in older adults or people with weak immune systems. Immunotherapy transformed treatment once it spreads. The open question is whether giving it earlier, after or before surgery, prevents relapse.

• 64studies open or running
• 4phase 3 trials
• 274papers published this year
• 40NIH-funded projects

1. Now

   Nov 2026

   Immunotherapy first for advanced diseaseHappened 54.5% tumors shrank

   Pembrolizumab, avelumab and retifanlimab each shrink about half of advanced tumors, often for years.

   54.5%: had their tumors shrink with retifanlimab.

   • POD1UM-201
   • KEYNOTE-017
   • JAVELIN Merkel 200

   One immunotherapy is enough at firstHappened 28% vs 47% serious side effects

   Adding ipilimumab did not improve results and doubled serious side effects.

   28% vs 47%: had serious side effects, nivolumab alone vs with ipilimumab.

   • CheckMate 358

2. 6 months

   by May 2027

   Immunotherapy after surgery: first big answerLikely

   A 280-person NCI trial of pembrolizumab after surgery and radiation is fully enrolled and due December 2026.

   • STAMP trial

   Avelumab after surgery, EuropePossible

   A 122-person placebo-controlled trial of avelumab after treatment for stage I-III disease is due November 2026.

   • ADMEC-O trial

3. 12 months

   by Nov 2027

   Help when immunotherapy stops workingPossible

   A placebo-controlled trial tests IFx-Hu2.0, an injected immune booster, before pembrolizumab in resistant disease. Due March 2027.

   • IFx-Hu2.0 trial

4. 3 years

   by late 2029

   Immunotherapy after surgery becomes standardPossible

   If the trials are positive, immunotherapy after surgery would be offered to people at high risk of relapse.

   • STAMP trial
   • ADAM trial

   Immunotherapy before surgeryLong shot

   A German trial of 135 people gives cemiplimab before surgery. It finishes in 2029.

   • Cemiplimab before surgery

5. 5 years

   by late 2031

   Treatment for transplant recipientsLong shot

   Trials adapt immunotherapy for people on anti-rejection drugs, who get Merkel cell carcinoma more often.

   • Kidney transplant trial
   • RP1 trial

   Shorter immunotherapy coursesPossible

   A French trial tests spacing out immunotherapy doses after a good response, across several cancers including this one.

   • MOIO trial

The research paths

Borrowed from other cancers

Open to join now

• Resistant to immunotherapy

  IFx-Hu2.0 then pembrolizumab

  Phase 3 · 18 sites

  Locations and eligibility →

• Resectable disease, Germany

  Cemiplimab before surgery

  Phase 2 · 12 sites

  Locations and eligibility →

• Transplant recipients

  Immunotherapy for kidney transplant recipients

  Phase 2 · 26 sites

  Locations and eligibility →

• Advanced solid tumors

  AZD6750 with rilvegostomig

  Phase 2 · 13 sites

  Locations and eligibility →

See every recruiting Merkel cell carcinoma trial →

When the trials finish

Completion dates the trials registered. Results usually follow 3 to 12 months later.

Knowledge on the way

Not treatments yet: detection, causes and how care is delivered. Mostly NIH-funded.

• AreaQuestionFunded throughNews likely
• Biology How the immune system controls Merkel cell carcinoma, and immune therapy for itUniversity of Washington · NIH Funded through Jul 2030 News likely 2028–2030
• Biology Shared switches behind neuroendocrine cancersDana-Farber · NIH Funded through Mar 2030 News likely 2028–2030

What just happened

Standard treatment today

• LocalizedSurgery with clear margins and a sentinel lymph node biopsy, often followed by radiation.
• Spread to lymph nodesSurgery and/or radiation; immunotherapy after surgery is being tested.
• Spread furtherImmunotherapy (avelumab, pembrolizumab or retifanlimab) first; chemotherapy if it fails.

See Merkel cell carcinoma trials recruiting now →