Retifanlimab

Retifanlimab is a prescription medication indicated for the treatment of:

• Squamous cell carcinoma of the Anal canal (SCAC):
  • as a single-agent therapy for the treatment of locally recurrent or metastatic SCAC in adults with disease progression on or intolerance to platinum-based chemotherapy
  • in combination with carboplatin and paclitaxel for first-line treatment for inoperable, locally recurrent or metastatic SCAC
• Metastatic or recurrent locally advanced Merkel cell carcinoma (MCC)

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

Common side effects of Retifanlimab include:

• tiredness
• numbness, pain, tingling or burning in the hands or feet
• nausea
• hair loss
• diarrhea
• muscle and bone pain
• constipation
• bleeding
• rash
• vomiting
• decreased appetite
• itching
• abdominal pain
• infection
• rectal or genital-area pain
• nausea
• shortness of breath
• fever
• low thyroid levels
• headache
• decreased weight

Serious side effects of Retifanlimab include:

• lung problems may cause symptoms like cough, shortness of breath, and chest pain
• intestinal problems may cause symptoms like diarrhea (loose stools) or more frequent bowel movements than usual, stools that are black, tarry, sticky, or have blood or mucus and severe abdominal pain or tenderness
• liver problems may cause symptoms like yellowing of the skin or the whites of the eyes, dark urine, severe nausea or vomiting, bleeding or bruising more easily than normal, pain on the right side of the abdomen
• hormone gland problems may cause symptoms like unusual headaches, eye problems, sensitivity to light, rapid heartbeat, increased sweating, extreme tiredness, weight gain or weight loss, feeling more hungry or thirsty than usual, urinating more often than usual, hair loss, feeling cold, constipation, voice getting deeper, dizziness or fainting, changes in mood or behavior, such as decreased sex drive, irritability or forgetfulness
• kidney problems may cause symptoms like reduced urine output, swelling of the ankles, blood in the urine, loss of appetite
• skin problems may cause symptoms like rash, itching, skin blistering or peeling, painful sores or ulcers in your mouth or nose, throat, or genital area, fever or flu-like symptoms, swollen lymph nodes
• symptoms of infusion reactions may include chills or shaking, dizziness, itching or rash, feeling like passing out, flushing, fever, shortness of breath or wheezing, and back pain
• risk of rejection of a transplanted organ or tissue
• complications, including graft-versus-host disease, in people who have received a bone marrow transplant

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

Anal cancer

Adult dosage

• Single-agent therapy
  • 500 mg IV every 4 weeks until disease progression, unacceptable toxicity, or up to 24 months
• Combination therapy
  • 500 mg IV on Day 1 repeated every 28 days for 6 cycles, plus
  • Carboplatin (AUC, 5) IV on Day 1 repeated every 28 days for 6 cycles, and
  • Paclitaxel 80 mg/m2 IV on Days 1, 8, and 15 repeated every 28 days for 6 cycles
  • After 6 cycles of combination therapy, continue single-agent retifanlimab 500 mg IV every 4 weeks until disease progression, unacceptable toxicity, or up to 12 months

Merkel Cell Carcinoma

Adult dosage

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

Tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Visit the RxList Drug Interaction Checker for any drug interactions. 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

• Immune-mediated adverse reactions
  • Severe and fatal immune-mediated reactions reported
  • May occur in any organ system or tissue and at any time after starting therapy, including after discontinuation
  • For suspected reactions, initiate appropriate workup to exclude alternative etiologies (e.g., infection)
  • Institute medical management promptly; consult specialists as appropriate
  • Hold or permanently discontinue based on severity
  • Administer systemic corticosteroids (eg, 1-2 mg/kg/day prednisone or equivalent) until improvement to Grade 1 or less, then taper corticosteroids over at least 1 month
  • Other systemic immunosuppressants may be required if reactions are not controlled with corticosteroids
• Immune-mediated pneumonitis
  • Incidence of pneumonitis is higher following prior thoracic radiation
• Immune-mediated colitis
  • Cytomegalovirus (CMV) infection/reactivation reported with corticosteroid-refractory immune-mediated colitis
  • For corticosteroid-refractory colitis, consider repeating the infectious workup to exclude alternative etiologies
• Immune-mediated hepatitis
  • Evaluate liver enzymes before initiating and periodically during therapy
• Immune-mediated endocrinopathies
  • Immune-mediated adrenal insufficiency, hypophysitis, thyroiditis, hyperthyroidism, hypothyroidism, and type 1 diabetes mellitus (may present with diabetic ketoacidosis) reported
  • Hypophysitis can cause hypopituitarism
  • Initiate symptomatic treatment (eg, hormone replacement, insulin) as clinically indicated
  • Evaluate thyroid function before initiation and periodically during therapy
  • Monitor for hyperglycemia and other signs of diabetes
• Immune-mediated nephritis
  • May occur with renal dysfunction
  • Evaluate renal function before initiation and periodically during therapy
  • Immune-mediated dermatologic reactions
  • Can cause rash or dermatitis
  • Bullous and exfoliative dermatitis may occur (eg, Stevens-Johnson syndrome [SJS], drug rash with eosinophilia and systemic symptoms [DRESS], and toxic epidermal necrolysis [TEN])
  • Treat mild to moderate nonexfoliative rashes with topical emollients and/or topical corticosteroids
  • Hold or permanently discontinue depending on severity

Infusion-related reactions

• Severe infusion-related reactions reported
  • Monitor for signs and symptomsInterrupt, reduce infusion rate, or permanently discontinue based on severity
  • Consider premedication with antipyretic and/or antihistamine for patients who have had previous systemic reactions to infusions of therapeutic proteins
  • 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 blocking antibody
  • Transplant-related complications include hyperacute graft-versus-host-disease (GVHD), acute GVHD, chronic GVHD, hepatic veno-occlusive disease (VOD) after reduced-intensity conditioning, and steroid-requiring febrile syndrome (without an identified infectious cause)
  • These complications may occur despite intervening therapy between PD-1 blockade and allogeneic HSCT
  • Follow patients closely for evidence of transplant-related complications and intervene promptly
  • Consider the benefits versus risks of treatment with a PD-1 blocking antibody prior to or after an allogeneic HSCT
• Embryo-fetal toxicity
  • Fetal harm may occur if used during pregnancy
  • Advise pregnant patients of the potential risk to the fetus
  • Effective contraception is recommended during and after therapy in females of reproductive potential