You are using an outdated browser. We suggest you update your browser for a better experience. Click here for update.
Close this notification.
Skip to main content Skip to search

COVID-19: Get the latest updates or take a self-assessment.

Screen for hepatitis B virus in all cancer patients starting systemic treatment. Find out more about hepatitis B virus screening and management.

Drug Formulary information is intended for use by healthcare professionals. It is not intended to be medical advice. Some of the information, including information about funding for cancer drugs, does not apply to all patients. Cancer treatment plans are unique to each patient. If you are a patient, please speak with your healthcare team to understand how this information applies to you.


( SEM ip LI mab )
New Drug Funding Program
  • Cemiplimab - Metastatic or Locally Advanced Cutaneous Squamous Cell Carcinoma
Other Name(s): Libtayo™
Appearance: clear to slightly opalescent, colourless to pale yellow solution mixed into larger bags of fluids
A - Drug Name



B - Mechanism of Action and Pharmacokinetics

Cemiplimab is a recombinant human immunoglobulin G4 (IgG4) monoclonal antibody that binds to the PD-1 receptor on T-cells, blocking interaction with PD-L1 and PD-L2 and countering PD-1 mediated immune response inhibition.


Cemiplimab exhibits linear and dose proportional pharmacokinetics in the dose range of 1 mg/kg to 10 mg/kg.


Cemiplimab clearance is approximately 39% at steady state.


19 days

C - Indications and Status
Health Canada Conditional Approvals
(pending the result of studies to verify the drug’s clinical benefit. Patients should be advised of the nature of the marketing authorization granted.)

For treatment of adult patients with metastatic or locally advanced cutaneous squamous cell carcinoma (CSCC) who are not candidates for curative surgery or curative radiation.


Marketing authorization with conditions is based on tumour response rate and durability of response; improvement in overall survival (OS) or progression free survival (PFS) has not yet been established.

D - Adverse Effects

Emetogenic Potential:  


Extravasation Potential:   None

The following adverse effects include those reported in ≥ 5 patients from the pivotal phase II study in metastatic CSCC. It also includes severe or life-threatening adverse effects from other sources or post-marketing.

Cardiovascular Myocarditis (<1%) E  D
Dermatological Rash, pruritus (15%) (including SJS, TEN; may be severe) E
Gastrointestinal Anorexia, weight loss (14%) E
Constipation (15%) E
Diarrhea (27%) (including colitis; may be severe) E
Mucositis (may be severe) E
Nausea, vomiting (17%) E
General Fatigue (24%) E
Hematological Immune thrombocytopenic purpura (rare) E  D
Myelosuppression (9%) (including anemia; 2% severe) E
Hepatobiliary ↑ LFTs (9%) (including hepatitis; may be severe) E  D
Hypersensitivity Infusion related reaction (3%) I
Immune Immune-mediated reactions - solid organ transplant rejection (rare) D  L
Other - Sjogren's syndrome (rare) E  D
Metabolic / Endocrine Adrenal insufficiency (<1%) E  D
Diabetes mellitus (<1%) (new onset) E  D
Hyperthyroidism (2%) (< 1% severe) E  D
Hypophysitis (<1%) E  D
Hypothyroidism (9%) E  D
Nervous System Headache (14%) E
Meningitis (<1%) E
Myasthenia (rare) E  D
Myositis (rare) E  D
Neurotoxicity (<1%) E  D
Renal Nephritis (<1%) E  D
Respiratory Cough (14%) E
Pneumonitis (9%) (3% severe) E  D
Vascular Vasculitis (rare) E

* "Incidence" may refer to an absolute value or the higher value from a reported range.
"Rare" may refer to events with < 1% incidence, reported in post-marketing, phase 1 studies,
isolated data or anecdotal reports.

** I = immediate (onset in hours to days)     E = early (days to weeks)
D = delayed (weeks to months)      L = late (months to years)

The most common side effects for cemiplimab include diarrhea, fatigue, nausea, vomiting, constipation, rash, pruritus, anorexia, weight loss, cough, and headache.

Refer to CCO's Immune Checkpoint Inhibitor Toxicity Management Guideline for detailed descriptions of Immune-related toxicities and their management.

Immune-related pneumonitis, including fatal cases, has been reported. Evaluate patients with suspected pneumonitis with radiographic imaging and manage with treatment modifications and corticosteroid. The median time to onset was 2 months and the median duration of pneumonitis was 25 days.

Immune-related diarrhea or colitis has been observed. The median time to onset was 4 months and the median duration was 23 days.

Severe or fatal cases of immune-related hepatitis have been observed in patients treated with cemiplimab. Two percent of patients experienced > Grade 3 immune-related hepatitis. The median time to onset was 1 month and the median duration of hepatitis was 15 days.

Immune-related endocrinopathies, including thyroid disorders, hypophysitis, adrenal insufficiency and type 1 diabetes mellitus, have occurred. Thyroid disorders can occur at any time during the treatment. For hypothyroidism, the median time to onset and duration were 4 months and 5 months, respectively. For hyperthyroidism, the median time to onset and duration were 2 months and 1 month, respectively. The median time to onset and duration for adrenal insufficiency were 11 months and 3 months, respectively. Type 1 diabetes mellitus, including diabetic ketoacidosis, has been observed with a median time to onset of  2 months.

Severe or fatal immune-related skin adverse reactions, including rash, erythema multiforme, pemphigoid, and Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) have been observed. The median time to onset was 1 month and the median duration was 2 months.

Immune-related nephritis has been rarely reported with a median time to onset of 2 months and a median duration of nephritis of 18 days.

Immune-related nervous system disorders occurred rarely, including paraneoplastic encephalomyelitis, Guillain-Barre syndrome, encephalitis, chronic inflammatory demyelinating polyradiculoneuropathy and central nervous system inflammation.

Cases of immune-related adverse reactions have been reported in patients with prior treatment with idelalisib.

Cases of solid organ transplant rejection have been reported during postmarketing surveillance. Cemiplimab may increase the risk of organ rejection; consider the benefit versus the risk of treatment.

Infusion-related reactions occurred in 9% of patients, including 1 patient with Grade 3 infusion-related reaction. 

E - Dosing

Refer to protocol by which patient is being treated. 

Screen for hepatitis B virus in all cancer patients starting systemic treatment. Refer to the hepatitis B virus screening and management guideline.

Premedication (prophylaxis for infusion reactions):

  • Routine pre-medication is not recommended. No premedication was given for the first dose of cemiplimab during clinical trials.
  • May consider premedication in patients who experienced a grade 1-2 infusion reaction (Migden et al). Refer to Management of Infusion-related Reactions table.


Intravenous: 350 mg Every 3 weeks


(in patients with a low body weight at the discretion of the treating healthcare professional)

Intravenous: 3 mg/kg Every 2 weeks

Dosage with Toxicity:

Dose reductions are not recommended for cemiplimab. Doses may be delayed or discontinued based on toxicity.

Healthcare professionals should also consult the most recent cemiplimab product monograph for additional information.


Summary of Principles of Management of Immune-related Adverse Effects (irAEs):

  • Immune-related adverse effects (irAEs) are different in their presentation, onset and duration compared to conventional chemotherapy. Patient and provider education is essential.
  • Initial irAEs presentation can occur months after completion of treatment and affect multiple organs.
  • Dose escalation or reduction is not recommended.
  • If no other cause can be identified (such as infection), any new symptom should be considered immune-related and prompt treatment initiated.
  • Organ-specific system-based toxicity management is recommended.

Refer to CCO's Immune Checkpoint Inhibitor Toxicity Management Guideline for detailed descriptions of Immune-related toxicities and their management.



Management of Infusion-related Reactions:

Grade Management Re-challenge*
  • Stop or slow the infusion rate (e.g. 50%)

  • Manage the symptoms

Consider premedication (at least 30 min prior to infusion) with:

  • Diphenhydramine 50mg (or equivalent) and/or acetaminophen 325 mg to 1000 mg


  • Stop or slow the infusion rate (e.g. 50%)

  • Manage the symptoms

Consider premedication (at least 30 min prior to infusion) with:

  • Diphenhydramine 50mg (or equivalent) and/or acetaminophen 325 mg to 1000 mg

  • Corticosteroids (e.g. hydrocortisone 25 mg or equivalent) as necessary

3 or 4

  • Stop treatment

  • Aggressively manage symptoms

Permanently discontinue (do not re-challenge)

*Based on Migden et al.

Dosage with Hepatic Impairment:

No formal studies in patients with hepatic impairment have been conducted. Mild hepatic impairment had no effect on cemiplimab exposure based on limited data (n=5) of a population pharmacokinetic analysis. 

Cemiplimab has not been studied in patients with moderate or severe hepatic impairment.

Refer to CCO's Immune Checkpoint Inhibitor Toxicity Management Guideline for management of immune-related hepatic toxicities.



Dosage with Renal Impairment:

No formal studies in patients with renal impairment have been conducted.

Refer to CCO's Immune Checkpoint Inhibitor Toxicity Management Guideline for management of immune-related renal toxicities.

Creatinine Clearance (mL/min) Cemiplimab Starting Dose
> 30 No dose adjustment.
< 30 Limited data.

Dosage in the elderly:

No adjustment required for patients ≥ 75 years. Of the 163 patients in clinical trials, patients > 75 years of age experienced more Grade ≥ 3 treatment-related adverse reactions (18%) compared to patients < 75 years of age (9%). No overall differences in efficacy were observed between patients ≥ 75 years of age and < 75 years of age. 


Safety and efficacy in children have not been established.

F - Administration Guidelines

  • Undiluted solution should be clear to slightly opalescent, colourless to pale yellow; discard if cloudy, discoloured or contains extraneous particulate matter other than trace amounts of translucent-to-white particles.
  • Dilute in 0.9% Normal Saline or 5% Dextrose to a final concentration between 1 to 20mg/mL. Mix by gentle inversion; do not shake. 
  • Infuse over 30 minutes using a sterile, 0.2 to 5 micron in-line or add-on filter.
  • Do not co-administer with other drugs through the same infusion line.
  • Store vials at 2-8 °C; do not freeze. Protect from light.

G - Special Precautions

  • Patients who have a hypersensitivity to this drug or any of its components

Other Warnings/Precautions:

  • Cemiplimab may cause serious immune-related reactions affecting multiple organ systems. Use with caution and monitor closely in patients with pre-existing conditions such as colitis, hepatic or renal impairment, respiratory or endocrine disorders, such as hypo or hyperthyroidism or diabetes mellitus.
  • Patients experiencing fatigue should exercise caution when driving or operating machinery.

Other Drug Properties:

  • Carcinogenicity: Unknown

Pregnancy and Lactation:
  • Genotoxicity: Unknown
  • Teratogenicity: Unknown

    Cemiplimab is not recommended for use in pregnancy. Adequate contraception should be used by both sexes during treatment, and for at least 4 months after the last dose.

    Animal reproduction studies have not been conducted.

  • Excretion into breast milk: Unknown

    Breastfeeding is not recommended during treatment and for at least 4 months after the last dose.

  • Fertility effects: Unknown

    No clinical data on fertility are available; no effects on fertility or in the male and female reproductive organs were observed in animal studies.

H - Interactions

No drug interaction studies have been conducted.

Use of systemic corticosteroids or immunosuppressants should be avoided prior to starting cemiplimab due to the potential interference with efficacy. They can be used after initiating cemiplimab to treat immune-mediated reactions .

Acetaminophen may affect the response to immune checkpoint inhibitors. Further clinical studies are needed to determine the exact mechanism and the appropriate clinical management (Bessede et al, 2022).

I - Recommended Clinical Monitoring

Treating physicians may decide to monitor more or less frequently for individual patients but should always consider recommendations from the product monograph.

Refer to the hepatitis B virus screening and management guideline for monitoring during and after treatment.

Recommended Clinical Monitoring

Monitor Type Monitor Frequency


Baseline and as clinically indicated

Liver function tests

Baseline, before each dose and as clinically indicated; frequent with severe toxicity

Renal function tests

Baseline, before each dose and as clinically indicated; frequent with severe toxicity

Blood glucose

Baseline, before each dose and as clinically indicated; frequent with severe toxicity

Thyroid function tests

Baseline, before each dose and as clinically indicated

Clinical toxicity assessment for infusion-related reactions, immune-related reactions, including diarrhea, endocrine, skin, neurologic, cardiac, respiratory, ocular and vascular toxicities

At each visit

Grade toxicity using the current NCI-CTCAE (Common Terminology Criteria for Adverse Events) version

J - Supplementary Public Funding

New Drug Funding Program (NDFP Website )

  • Cemiplimab - Metastatic or Locally Advanced Cutaneous Squamous Cell Carcinoma

K - References

Bessede A, Marabelle A, Guegan JP, et al. Impact of acetaminophen on the efficacy of immunotherapy in cancer patients. Ann Oncol 2022;33(9):909-15.

Migden MR, Khushalani K, Chang ALS, et al. Cemiplimab in locally advanced cutaneous squamous cell carcinoma: results from an open-label, phase 2, single-arm trial. Lancet Oncol. 2020 Feb;21(2):294-305.

Migden MR, Rischin D, Schmults CD, et al. PD-1 blockade with cemiplimab in advanced cutneous squamous-cell carcinoma. N Engl J Med 2018;379:341-51.

National Comprehensive Cancer Network. Clinical Practice Guidelines in Oncology: Antiemesis: Version 2.2020, 2020.

Prescribing information: Libtayo (cemiplimab). Regeneron Pharmaceuticals, Inc. June 2020.

Product information: Libtayo (cemiplimab). Regeneron Ireland DAC. May 20, 2020.

Product monograph: Libtayo (cemiplimab). Sanofi-Aventis Canada Inc. August 26, 2020.

February 2023 Updated Interactions section

L - Disclaimer

Refer to the New Drug Funding Program or Ontario Public Drug Programs websites for the most up-to-date public funding information.

The information set out in the drug monographs, regimen monographs, appendices and symptom management information (for health professionals) contained in the Drug Formulary (the "Formulary") is intended for healthcare providers and is to be used for informational purposes only. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects of a particular drug, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for a given condition. The information in the Formulary is not intended to constitute or be a substitute for medical advice and should not be relied upon in any such regard. All uses of the Formulary are subject to clinical judgment and actual prescribing patterns may not follow the information provided in the Formulary.

The format and content of the drug monographs, regimen monographs, appendices and symptom management information contained in the Formulary will change as they are reviewed and revised on a periodic basis. The date of last revision will be visible on each page of the monograph and regimen. Since standards of usage are constantly evolving, it is advised that the Formulary not be used as the sole source of information. It is strongly recommended that original references or product monograph be consulted prior to using a chemotherapy regimen for the first time.

Some Formulary documents, such as the medication information sheets, regimen information sheets and symptom management information (for patients), are intended for patients. Patients should always consult with their healthcare provider if they have questions regarding any information set out in the Formulary documents.

While care has been taken in the preparation of the information contained in the Formulary, such information is provided on an “as-is” basis, without any representation, warranty, or condition, whether express, or implied, statutory or otherwise, as to the information’s quality, accuracy, currency, completeness, or reliability.

CCO and the Formulary’s content providers shall have no liability, whether direct, indirect, consequential, contingent, special, or incidental, related to or arising from the information in the Formulary or its use thereof, whether based on breach of contract or tort (including negligence), and even if advised of the possibility thereof. Anyone using the information in the Formulary does so at his or her own risk, and by using such information, agrees to indemnify CCO and its content providers from any and all liability, loss, damages, costs and expenses (including legal fees and expenses) arising from such person’s use of the information in the Formulary.