Patient Medication Information: uses, side effects, how to take - Zynyz
What is Zynyz used for?
Zynyz is a prescription medicine used to treat:
Squamous cell carcinoma of the anal canal
- adults with squamous cell carcinoma of the anal canal. It is given when the cancer has spread or returned after initial treatment and cannot be treated with surgery. When used to treat this type of cancer, Zynyz is given in combination with chemotherapy medicines carboplatin and paclitaxel.
Merkel cell carcinoma
- adults with Merkel cell carcinoma, a rare type of skin cancer. It is given when the cancer has spread or returned and cannot be treated with surgery or radiation. When used to treat this type of cancer, Zynyz is given alone.
How does Zynyz work?
Zynyz works by helping your immune system fight your cancer.
What are the ingredients in Zynyz?
Medicinal ingredients: retifanlimab
Non-medicinal ingredients: Glacial acetic acid, polysorbate 80, sodium acetate, sucrose, and water for injection.
Zynyz comes in the following dosage forms:
Zynyz comes in a 20 mL glass vial containing 500 mg of retifanlimab.
Do not use Zynyz if:
- You are allergic to retifanlimab or any of the other ingredients in this medicine. Talk to your health care professional if you are not sure.
To help avoid side effects and ensure proper use, talk to your healthcare professional before you take Zynyz. Talk about any health conditions or problems you may have, including if you have:
- an autoimmune disease (a condition where the body’s immune system attacks its own cells)
- lung or breathing problems
- liver problems
- kidney problems
- diabetes
- have or have had myasthenia gravis or myasthenic syndrome (conditions affecting muscle strength)
- have or have had myocarditis (inflammation of the heart muscle)
- have or have had myositis (inflammation of the muscles)
- solid organ transplant or a bone marrow (stem cell) transplant that used donor stem cells (allogeneic hematopoietic stem cell transplantation)
- any other medical conditions
Other warnings you should know about:
Pregnancy:
- You must not be given Zynyz if you are pregnant unless your doctor specifically recommends it.
- Zynyz can cause harmful effects or death to your unborn baby.
- If you are pregnant, think you may be pregnant, or are planning to have a baby, ask your doctor for advice before you are given this medicine.
- Women who could become pregnant must use effective contraception during treatment and for at least 4 months after the last Zynyz dose.
Breastfeeding:
- Do not breastfeed during treatment and for at least 4 months after your last dose of Zynyz.
- It is not known if Zynyz passes into breast milk. A risk to the breastfeeding newborns/infants cannot be excluded.
- Ask your doctor for advice if you are breastfeeding.
Children and adolescents:
- Zynyz should not be used in children and adolescents below 18 years of age.
Driving and using machines
- Zynyz may have an influence on the ability to drive and use machines. If you feel tired, do not drive or use machines until you feel better.
Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements, or alternative medicines.
- This applies in particular to medicines that suppress your immune system, such as corticosteroids, which may disrupt the effect of Zynyz. Once you are treated with Zynyz, your doctor may prescribe corticosteroids to reduce side effects that you may have during treatment. This will not impact the effect of the medicine.
How to take Zynyz:
- Zynyz will be given to you in a hospital or clinic, supervised by a doctor experienced in cancer treatment.
- Your doctor will give you Zynyz as a drip into a vein (intravenous infusion) which will last about 30 minutes.
Usual dose:
- The recommended dose of Zynyz is 500 mg every 4 weeks.
- Your doctor will decide how many treatments you need.
Overdose:
If you think you, or a person you are caring for, have taken too much Zynyz, contact a healthcare professional, hospital emergency department, or regional poison control centre immediately, even if there are no symptoms.
Missed Dose:
- It is very important that you do not miss a dose of this medicine.
- Contact your doctor or hospital immediately to reschedule your appointment.
What are possible side effects from using Zynyz?
These are not all the possible side effects you may have when taking Zynyz. If you experience any side effects not listed here, tell your healthcare professional.
These side effects may happen at any time during treatment, or even after your treatment has ended. You may get more than one side effect at the same time, involving any organs and tissues. Sometimes the side effect(s) could be severe or life-threatening and rarely, fatal. If you experience any symptoms that are severe enough to interfere with daily activities, notify your healthcare professional immediately or proceed to the emergency department.
The following side effects have been reported in a clinical trial of patients with squamous cell carcinoma of the anal canal treated with Zynyz in combination with chemotherapy:
Very common (may affect more than 1 in 10 people):
- diarrhea
- inflammation of the mouth or mouth sores (stomatitis)
- inflammation of the nerves causing tingling, numbness, weakness or burning pain of the arms or legs (peripheral neuropathy)
- muscle and bone pain (musculoskeletal pain)
- bleeding
- rash
itching of the skin (pruritus)
- underactive thyroid gland (hypothyroidism)
- a low number of red blood cells in your blood (anemia)
- low white blood cell count (leukopenia)
- low level of platelets in your blood (thrombocytopenia)
- vomiting
- fatigue
- fever
Common (may affect up to 1 in 10 people):
- decreased secretion of hormones produced by the adrenal glands (adrenal insufficiency and secondary adrenocortical insufficiency)
- overactive thyroid gland (hyperthyroidism)
- inflammation of the pituitary gland in the base of the brain (hypophysitis)
- decreased blood levels of sodium (hyponatraemia)
- inflammation of the liver (hepatitis)
- increased blood level of liver enzymes, including aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltransferase
- infusion-related reactions that can cause symptoms such as chills, shaking or fever, itching or rash, flushing or swollen face, being short of breath or wheezing, feeling dizzy or nausea
- blurry vision
Uncommon (may affect up to 1 in 100 people):
- thyroid gland inflammation (thyroiditis)
- inflammation of the bile ducts (cholangitis)
The following side effects have been reported in clinical trials of patients with Merkel cell carcinoma treated with Zynyz alone:
Very common (may affect more than 1 in 10 people):
- diarrhea
- nausea
- constipation
- rash
itching of the skin (pruritus)
- joint pain (arthralgia)
- tiredness (fatigue)
- fever (pyrexia)
- muscle and bone pain (musculoskeletal pain)
- cough
Common (may affect up to 1 in 10 people):
- decrease in the number of red blood cells (anemia)
- thyroid gland problems (hypothyroidism, hyperthyroidism, autoimmune thyroiditis)
- decreased secretion of hormones produced by the adrenal glands (adrenal insufficiency)
- decreased appetite
- abnormal sensation such as tingling or numbness of the hands or feet (paraesthesia)
- increased blood level of liver enzymes, including alanine aminotransferase and aspartate aminotransferase
- increased blood levels of creatinine
- increased blood levels of thyroid stimulating hormone
infusion-related reactions that can cause
- symptoms such as chills, shaking or fever, itching or rash, flushing or swollen face, being short of breath or wheezing, feeling dizzy or nausea.
- inflammation of the liver (hepatitis)
- inflammation of the lungs (pneumonitis)
- build up of fluid in the body or extremities causing swelling (edema)
- urinary tract infection
- high blood pressure (hypertension)
- abdominal pain
- dry mouth
- trouble sleeping (insomnia)
- redness of the skin (erythema)
- shortness of breath (dyspnea)
- vomiting
- headache
- muscle pain (myalgia)
- dry skin
inflammation of the mouth or mouth sores
- (stomatitis)
- lung infection (pneumonia)
- inflammation of the nerves causing tingling, numbness, weakness or burning pain of the arms or legs (peripheral neuropathy)
Uncommon (may affect up to 1 in 100 people):
- inflammation of the pancreas (pancreatitis)
- diabetic ketoacidosis that can cause symptoms such as difficulty thinking clearly, sleepiness, stomach pain, fast and deep breathing, breath that smells sweet or fruity, sweet or metallic taste in the mouth or a different odor to urine or sweat
- inflammation of the eyes (uveitis)
- inflammation of the tissue between the muscle and skin which may cause skin swelling (eosinophilic fasciitis)
- joint inflammation (polyarthritis)
- damage to the nerves and nerve coverings (demyelinating polyneuropathy)
- inflammation of the kidneys (tubulointerstitial nephritis)
Serious Side Effects and What to Do About Them
| Serious Side Effects and What to Do About Them | |||
|---|---|---|---|
| Symptom / Effect | Talk to Your Healthcare Professional | ||
| Symptom / Effect | Talk to Your Healthcare Professional | ||
| Only if Severe | In All Cases | ||
| Only if Severe | In All Cases | ||
| COMMON (may affect up to 1 in 10 people) | |||
| Lung inflammation (pneumonitis): breathing difficulties, chest pain, or new or worsening cough | x | ||
| Bowel inflammation (colitis): frequent diarrhea often with blood and/or mucus, more bowel movements than usual, stools that are bloody, black or tarry and severe abdominal pain or tenderness. | x | ||
| Sudden kidney damage (acute kidney injury): decreased volume of urine, foamy urine, passing blood or traces of blood in the urine that may change its color, swollen ankles, or loss of appetite. | x | ||
| Infusion-related reaction: chills, shaking or fever, itching or rash, flushing or swollen face, being short of breath or wheezing, feeling dizzy or feel like passing out and back or neck pain, nausea, vomiting, or abdominal pain. | x | ||
| Inflammation of the pituitary gland in the base of the brain (hypophysitis): headache, nausea, vomiting, increased thirst, vision changes | x | ||
| UNCOMMON (may affect up to 1 in 100 people) | |||
| Liver inflammation (hepatitis): persistent nausea or vomiting, loss of appetite, pain on the right side of your stomach, eye and/or skin yellowing, drowsiness, dark-colored urine, bleeding, or bruising more easily than normal. | x | ||
| Acid in the blood produced from diabetes (diabetic ketoacidosis) | x | ||
| Pinched nerve caused by damage to the root of the nerve(s) in the spine (radiculopathy) | x | ||
| Inflammation of the pancreas (pancreatitis) | x | ||
| Inflammation of the heart muscle (myocarditis): chest pain, shortness of breath, fatigue, rapid swelling in the legs, ankles or feet | x | ||
| Inflammation of the muscles (myositis): gradual muscle weakness in the hips, thighs, shoulders, and neck, muscle pain/tenderness, fatigue | x | ||
| Conditions affection muscle strength (myasthenia gravis/myasthenic syndrome): drooping eyelids, double vision, difficulty speaking, swallowing, or chewing | x | ||
If you have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.
Reporting Side Effects
You can report any suspected side effects associated with the use of health products to Health Canada by:
- Visiting the Web page on Adverse Reaction Reporting (https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada.html) for information on how to report online, by mail or by fax; or
- Calling toll-free at 1-866-234-2345.
NOTE: Contact your health professional if you need information about how to manage your side effects. The Canada Vigilance Program does not provide medical advice.
Storage:
It is unlikely that you will be asked to store Zynyz yourself. It will be stored in the hospital or clinic where it is given to you.
Store in a refrigerator (2°C-8°C). Do not freeze. Store in the original package in order to protect from light. Keep out of reach and sight of children.
If you want more information about Zynyz:
- Talk to your healthcare professional
- Find the full product monograph that is prepared for healthcare professionals and includes this Patient Medication Information by visiting the Health Canada website: https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html, the manufacturer’s website: www.incytebiosciences.ca, or by calling 1 833-309-2759.
Date of Authorization: 2026-05-28