Zynyz (retifanlimab-dlwr)
An approved treatment for Merkel Cell Carcinoma.
The same compound appears under different names depending on the context. Here is how to identify Retifanlimab-dlwr wherever you encounter it, plus the key facts at a glance.
- Generic name
- Retifanlimab-dlwr
- Brand name
- Zynyz
- Development codes
- INCMGA00012, MGA012
- Drug class
- PD-1 blocking antibody (immune checkpoint inhibitor)
- Manufacturer
- Incyte
- How it's taken
- For Merkel cell carcinoma, 500 mg is given by a healthcare provider as an IV infusion over 30 minutes every 4 weeks, for up to 24 months or until the cancer grows or side effects become unacceptable.
An immunotherapy given as a 30-minute IV infusion every 4 weeks for adults with Merkel cell carcinoma that has spread to distant sites (metastatic) or has come back and grown in the same area (recurrent locally advanced). The FDA first approved it for this use on March 22, 2023 under accelerated approval and converted it to full approval on December 17, 2025. In its main trial, tumors shrank substantially or disappeared in 55% of patients who had not had prior drug treatment for advanced disease.
Where Retifanlimab-dlwr fits
Zynyz joins avelumab (Bavencio) and pembrolizumab (Keytruda), whose labels also include advanced Merkel cell carcinoma. Its approval rested on a single-arm trial with no comparison group, so its label offers no head-to-head data against them.
How Retifanlimab-dlwr works
PD-1 is a checkpoint, an off switch on T cells, the immune cells that find and kill abnormal cells. Some tumors carry proteins called PD-L1 and PD-L2 that bind PD-1 and switch those T cells off. Retifanlimab binds PD-1 and blocks it from connecting to PD-L1 and PD-L2, so the T cells stay active against the cancer. Because the same brake also keeps the immune system from attacking healthy tissue, releasing it can cause inflammation in normal organs, which is the source of the drug's main side effects[1].
Mechanism: Humanized monoclonal antibody that blocks the PD-1 receptor on T cells, releasing a brake on the immune system so it can attack cancer cells
Side effects and safety
- Immune-mediated side effects. Inflammation of the lungs, bowel, liver, kidneys, skin or hormone glands (thyroid, adrenal, pituitary, pancreas) can be severe or fatal. Report new cough, shortness of breath, diarrhea, yellow skin or eyes, rash, severe tiredness or other new symptoms right away. Treatment may be held or stopped and steroids given.
- Infusion-related reactions. Severe reactions occurred in 0.8% of 606 patients. The infusion can be slowed, interrupted or stopped.
- Stem cell transplant complications. Serious or fatal complications, including graft-versus-host disease, can occur in people who have a donor (allogeneic) stem cell transplant before or after a PD-1 or PD-L1 blocker.
- Harm to an unborn baby. A pregnancy test comes first. Use effective birth control during treatment and for 4 months after the last dose, and do not breastfeed during treatment and for 4 months after.
- Liver enzymes, creatinine (kidney function) and thyroid function at baseline and periodically during treatment
- Watch for high blood sugar or other signs of diabetes
- Pregnancy status before starting in women who can become pregnant
Zynyz has no boxed warning and no contraindications. Its main warning covers immune-mediated side effects, where the released immune system attacks healthy organs; these can be severe or fatal and can appear during treatment or after it ends. Among 452 patients who received Zynyz alone in trials, these included hypothyroidism (underactive thyroid, 10%), immune-related skin reactions (10%), hyperthyroidism (overactive thyroid, 6%), hepatitis (3.5%), pneumonitis (lung inflammation, 3.1%, including 1 death), colitis (2.7%) and nephritis (kidney inflammation, 2%). Other warnings cover infusion reactions, complications of a donor stem cell transplant before or after treatment, and harm to an unborn baby. In the Merkel cell trial of 107 patients, the most common side effects were musculoskeletal pain (37%), fatigue (33%), itching (22%), diarrhea (19%), rash (17%), fever (12%), nausea (12%) and constipation (11%). Serious side effects occurred in 26%, and 21% stopped Zynyz because of side effects. That trial had no placebo group, so these rates cannot be compared against placebo[1].
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Retifanlimab-dlwr
For Merkel cell carcinoma, 500 mg is given by a healthcare provider as an IV infusion over 30 minutes every 4 weeks, for up to 24 months or until the cancer grows or side effects become unacceptable. The dose is never lowered for side effects; instead, infusions are held or stopped, and steroids may be given for immune-mediated reactions[1].
Availability and cost
Only available as the brand-name product.
Help paying for Zynyz
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
IncyteCARES Savings Program: eligible patients with commercial prescription coverage may pay as little as $15 for Zynyz. Annual benefit maximum applies. Covers the medication cost only, not the cost of giving the infusion. Not valid with Medicare, Medicaid, TRICARE or state programs, or for uninsured or cash-paying patients.
For: private insurance · source - Free medicine program
IncyteCARES Patient Assistance Program: Zynyz free of charge for eligible patients who meet household income criteria and are uninsured, have Medicare Part B, Part D or Medicare Advantage, or have other insurance that has been exhausted or denied coverage for Zynyz. Proof of household income is required.
For: no insurance, underinsured, Medicare · source - Insurance and case manager help
IncyteCARES reviews insurance coverage, checks eligibility for savings or financial assistance and connects patients with other support. Monday to Friday, 8 AM to 8 PM ET.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: The page does not state the dollar amount of the copay program's annual maximum or the household income limits for the Patient Assistance Program. Call IncyteCARES at 1-855-452-5234 for details.
No charity fund for this condition is open right now. Funds reopen when they receive new donations; the foundations let you sign up to be told when one opens.
Access and eligibility
Approved for adults with metastatic or recurrent locally advanced Merkel cell carcinoma. Safety and effectiveness in children have not been established. The main trial required no prior systemic treatment for advanced disease and excluded people with active autoimmune disease or conditions needing immune suppression; people with HIV could join if the virus was undetectable, CD4 count was at least 300 and they were on treatment.
Source: IncyteCARES for Zynyz
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
The Merkel cell approval rested on POD1UM-201 (NCT03599713), an open-label, single-arm trial of 101 adults with metastatic or recurrent locally advanced Merkel cell carcinoma who had not had prior systemic treatment for advanced disease. Tumors shrank substantially or disappeared (objective response) in 55%, including 18% with a complete response, meaning no cancer could be seen on scans. Among responders, 69% were still responding at 12 months or longer and 46% at 24 months or longer. The median age was 71, and Merkel cell polyomavirus was found in 76% of tested tumors. Because there was no comparison group, the trial does not show how Zynyz compares with other treatments[1].
Development history
Incyte licensed global rights to retifanlimab from MacroGenics in 2017, and it was studied under the codes MGA012 and INCMGA00012[6][7]. The FDA granted accelerated approval for metastatic or recurrent locally advanced Merkel cell carcinoma on March 22, 2023, based on tumor response rate and how long responses lasted[2][6], and converted it to full (traditional) approval on December 17, 2025 after reviewing the final POD1UM-201 results[3]. Zynyz also has later uses in squamous cell carcinoma of the anal canal: on May 15, 2025 the FDA approved it with carboplatin and paclitaxel as first treatment for inoperable recurrent or metastatic disease, and alone after platinum chemotherapy[4]. A 375 mg every-3-weeks schedule was added for the anal cancer uses on March 30, 2026[5].
Explore Merkel Cell Carcinoma trials
Common questions about Retifanlimab-dlwr
▸What is Retifanlimab-dlwr (Zynyz)?
An immunotherapy given as a 30-minute IV infusion every 4 weeks for adults with Merkel cell carcinoma that has spread to distant sites (metastatic) or has come back and grown in the same area (recurrent locally advanced). The FDA first approved it for this use on March 22, 2023 under accelerated approval and converted it to full approval on December 17, 2025. In its main trial, tumors shrank substantially or disappeared in 55% of patients who had not had prior drug treatment for advanced disease.
▸How does Retifanlimab-dlwr work?
PD-1 is a checkpoint, an off switch on T cells, the immune cells that find and kill abnormal cells. Some tumors carry proteins called PD-L1 and PD-L2 that bind PD-1 and switch those T cells off. Retifanlimab binds PD-1 and blocks it from connecting to PD-L1 and PD-L2, so the T cells stay active against the cancer. Because the same brake also keeps the immune system from attacking healthy tissue, releasing it can cause inflammation in normal organs, which is the source of the drug's main side effects[1].
▸What are the side effects of Retifanlimab-dlwr?
Zynyz has no boxed warning and no contraindications. Its main warning covers immune-mediated side effects, where the released immune system attacks healthy organs; these can be severe or fatal and can appear during treatment or after it ends. Among 452 patients who received Zynyz alone in trials, these included hypothyroidism (underactive thyroid, 10%), immune-related skin reactions (10%), hyperthyroidism (overactive thyroid, 6%), hepatitis (3.5%), pneumonitis (lung inflammation, 3.1%, including 1 death), colitis (2.7%) and nephritis (kidney inflammation, 2%). Other warnings cover infusion reactions, complications of a donor stem cell transplant before or after treatment, and harm to an unborn baby. In the Merkel cell trial of 107 patients, the most common side effects were musculoskeletal pain (37%), fatigue (33%), itching (22%), diarrhea (19%), rash (17%), fever (12%), nausea (12%) and constipation (11%). Serious side effects occurred in 26%, and 21% stopped Zynyz because of side effects. That trial had no placebo group, so these rates cannot be compared against placebo[1].
▸How is Retifanlimab-dlwr taken?
For Merkel cell carcinoma, 500 mg is given by a healthcare provider as an IV infusion over 30 minutes every 4 weeks, for up to 24 months or until the cancer grows or side effects become unacceptable. The dose is never lowered for side effects; instead, infusions are held or stopped, and steroids may be given for immune-mediated reactions[1].
▸Is Retifanlimab-dlwr FDA approved?
Yes, Retifanlimab-dlwr (Zynyz) is FDA approved (2023) for the treatment of Merkel Cell Carcinoma.
▸Is Zynyz fully approved for Merkel cell carcinoma?
Yes. The FDA granted accelerated approval on March 22, 2023, based on how many tumors shrank and how long the responses lasted. On December 17, 2025, after reviewing final results from the POD1UM-201 trial, the FDA converted it to full (traditional) approval for adults with metastatic or recurrent locally advanced Merkel cell carcinoma.
▸How often is Zynyz given for Merkel cell carcinoma?
For Merkel cell carcinoma, 500 mg is given as a 30-minute IV infusion every 4 weeks, for up to 24 months or until the cancer grows or side effects become unacceptable. The 375 mg every-3-weeks schedule in the label applies only to anal cancer.
▸How well does Zynyz work for Merkel cell carcinoma?
In the POD1UM-201 trial of 101 adults who had no prior drug treatment for advanced disease, tumors shrank substantially or disappeared in 55%, and 18% had a complete response. Among responders, 69% were still responding at 12 months or longer and 46% at 24 months or longer. The trial had no comparison group.
▸What are the side effects of Zynyz?
In the Merkel cell trial, the most common were musculoskeletal pain (37%), fatigue (33%), itching (22%), diarrhea (19%), rash (17%), fever, nausea and constipation. Like other PD-1 blockers, Zynyz can cause the immune system to attack healthy organs such as the thyroid, lungs, bowel, liver or kidneys, so new symptoms should be reported right away.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2026-05. ZYNYZ (retifanlimab-dlwr) injection, for intravenous use: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=109648d0-d30a-42fc-8273-39cb1540a751
- U.S. Food and Drug Administration · 2023-03-22. BLA 761334 corrected approval letter (accelerated approval, effective March 22, 2023). https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2023/761334Orig1s000correctedltr.pdf
- U.S. Food and Drug Administration · 2025-12-17. BLA 761334/S-005 supplement approval (conversion to traditional approval). https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2025/761334Orig1s005ltr.pdf
- U.S. Food and Drug Administration · 2025-05-15. BLA 761334/S-004 supplement approval (squamous cell carcinoma of the anal canal). https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2025/761334Orig1s004ltr.pdf
- U.S. Food and Drug Administration · 2026-03-30. BLA 761334/S-008 supplement approval (375 mg every 3 weeks). https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2026/761334Orig1s008ltr.pdf
- Incyte · 2023-03-22. Incyte Announces FDA Approval of Zynyz (retifanlimab-dlwr) for the Treatment of Metastatic or Recurrent Locally Advanced Merkel Cell Carcinoma (MCC). https://investor.incyte.com/news-releases/news-release-details/incyte-announces-fda-approval-zynyztm-retifanlimab-dlwr
- ClinicalTrials.gov. A Study of INCMGA00012 in Metastatic Merkel Cell Carcinoma (POD1UM-201). https://clinicaltrials.gov/study/NCT03599713
- Incyte. Savings, Financial Assistance, and Support Options for ZYNYZ. https://www.incytecares.com/oncology-hematology-zynyz/financial-assistance
- U.S. National Library of Medicine, DailyMed. BAVENCIO (avelumab) injection: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5cd725a1-2fa4-408a-a651-57a7b84b2118
- U.S. National Library of Medicine, DailyMed. KEYTRUDA (pembrolizumab) injection: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9333c79b-d487-4538-a9f0-71b91a02b287