Retifanlimab

Retifanlimab is a prescription medication used to treat metastatic or recurrent locally advanced Merkel cell carcinoma in adults. 

• Retifanlimab is available under the following different brand names: Zynyz, retifanlimab-dlwr.

Common side effects of Retifanlimab include:

• Fatigue
• Decreased appetite.
• Nausea
• Diarrhea
• Urinary tract infection
• Constipation
• Fever
• Back or neck pain
• Itching
• Rash
• Vomiting
• Abdominal pain
• Shortness of breath
• Cough
• Joint pain
• Blood in the urine
• Anemia
• Hair fall
• Muscle pain
• A drop in red blood cells (anemia) which may make you feel tired and weak.

Serious side effects of Retifanlimab include:

• Fatigue, 
• Musculoskeletal pain, 
• Pruritus, 
• Diarrhea, 
• Rash, 
• Pyrexia, and nausea.

Rare side effects of Retifanlimab include:

• None 

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult dosage

Injectable solution

• 500 mg/20 mL (25 mg/mL) single-dose vial

Merkel Cell Carcinoma

Adult dosage

• 500 mg intravenous every 4 weeks
• Continue until disease progression, unacceptable toxicity, or up to 24 months.

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Retifanlimab has no noted severe interactions with any other drugs.
• Retifanlimab has no noted serious interactions with any other drugs.
• Retifanlimab has no noted moderate interactions with any other drugs.
• Retifanlimab has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, health questions, or concerns.

Contraindications

• None

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Retifanlimab?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Retifanlimab?”

Cautions

• Infusion-related reactions reported; interrupt or slow infusion rate, or permanently discontinue based on severity; consider premedication with antipyretic and/or an antihistamine in patients with a history of previous systemic reactions to infusions of therapeutic proteins.
• Based on the mechanism of action, can cause fetal harm when administered to pregnant females
• Complications of allogeneic HSCT
  • Fatal and other serious complications can occur in patients who receive allogeneic hematopoietic stem cell transplantation (HSCT) before or after being treated with a PD-1/PD-L1–blocking antibody.
  • Transplant-related complications include hyperacute graft-versus-host disease (GVHD), acute GVHD, chronic GVHD, hepatic veno-occlusive disease after reduced-intensity conditioning, and steroid-requiring febrile syndrome (without an identified infectious cause)
  • Closely monitor for evidence of transplant-related complications and intervene promptly; consider benefits versus risks of treatment with a PD-1/PD-L1–blocking antibody before or after an allogeneic HSCT.
• Severe and fatal immune-mediated adverse reactions
  • Also see Dosage Modifications
  • Can occur in any organ system or tissue and at any time after starting treatment with a PD-1/PD-L1–blocking antibody.
  • While immune-mediated adverse reactions usually manifest during treatment with PD-1/PD-L1–blocking antibodies, these adverse reactions can also manifest after discontinuation of PD-1/PD-L1–blocking antibodies.
  • May affect more than 1 body system simultaneously.
• Immune-mediated toxicities reported include:
  • Pneumonitis: in patients treated with other PD-1/PD-L1–blocking antibodies, the incidence of pneumonitis is higher in patients who have received prior thoracic radiation
  • Colitis: in cases of corticosteroid-refractory colitis, consider repeating infectious workup to exclude alternative etiologies
• Hepatitis
  • Endocrinopathies (. g, adrenal insufficiency, hypophysitis, thyroiditis, hyperthyroidism, hypothyroidism, type 1 diabetes mellitus, hypoparathyroidism)
• Nephritis with renal dysfunction
• Dermatologic
• Cardiac, vascular
• Gastrointestinal
• Musculoskeletal
• Neurological
• Ocular
• Hematologic

Pregnancy and Lactation

• Based on the mechanism of action, can cause fetal harm when administered to pregnant females
• Verify pregnancy status in females of reproductive potential before initiating.
• Inhibition of the PD-1/PD-L1 pathway can lead to an increased risk of immune-mediated rejection of the developing fetus resulting in fetal death.
• Human IgG4 immunoglobulins (IgG4) are known to cross the placenta; therefore, retifanlimab has the potential to be transmitted from the mother to the developing fetus; advise the patient of the potential risk to the fetus.
• Contraception
  • Advise females of reproductive potential to use effective contraception during treatment and for 4 months after the last dose.
• Lactation
  • Data are not available regarding the presence of retifanlimab in human milk, or its effects on breastfed children or milk production.
  • Maternal IgG is known to be present in human milk; the effects of local gastrointestinal exposure and limited systemic exposure in breastfed children are unknown.
  • Because of the potential for serious adverse reactions in breastfed children, do not breastfeed during treatment and for 4 months after the last dose.