Cemiplimab-Rwlc side effects: what 2,008 FDA adverse event reports show

Cemiplimab-Rwlc · Libtayo · 41 reaction terms · 755 drug–reaction co-reports · data 2026-09-14

Drug class

Programmed death receptor-1 (pd-1) blocking antibody

FDA label, Indications wording

Brand names

Libtayo

openFDA label

Who reports

2,008 reports · 82% serious · 418 with death outcome · 41% female

openFDA FAERS counts, all years, deduplication not applied

Used for

LIBTAYO is a programmed death receptor-1 (PD-1) blocking antibody indicated: Cutaneous Squamous Cell Carcinoma (CSCC) for the treatment of adult patients with metastatic cutaneous squamous cell carcinoma (mCSCC) or locally advanced CSCC (laCSCC) who are not candidates for curative surgery or curative radiation.

FDA label, Indications and Usage

What it is

Cemiplimab-rwlc is a human programmed death receptor-1 (PD-1) blocking antibody. Cemiplimab-rwlc is a recombinant human IgG4 monoclonal antibody that binds to PD-1 and blocks its interaction with PD-L1 and PD-L2.

FDA label, Description section

Boxed warning

None in the current label

How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation. Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)? That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.

Causality screen of the 25 strongest signals

Labeled adverse reaction 12Labeled (related wording) 3Likely indication confounding 2Reporting / coding artifact 1Not in label — unassessed 7

What the badges mean

Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.

Strongest disproportionality signals

Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 16 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Myocarditis	49	45.4 34.4–59.9ROR 46.5 · χ² 2,074 / p <1e-300	44.5 EB05 35.0 · IC025 +4.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 31.0 · 94% clinician	no trial data cached
Adrenal insufficiency	24	21.0 14.1–31.2ROR 21.2 · χ² 436 / p 4e-97	20.6 EB05 14.5 · IC025 +3.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 14.8	no trial data cached
Hepatic cytolysis	23	19.7 13.1–29.6ROR 19.9 · χ² 389 / p 7e-87	19.3 EB05 13.4 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 13.7 · ♀ 19% (drug 41%) · 96% clinician	no trial data cached
Squamous cell carcinoma	16	17.8 10.9–28.9ROR 17.9 · χ² 236 / p 1e-53	17.1 EB05 10.7 · IC025 +2.7 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 12.8	no trial data cached
Cholestasis (bile flow blockage)	26	14.2 9.7–20.9ROR 14.4 · χ² 307 / p 6e-69	13.8 EB05 9.6 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 10.0 · ♀ 14% (drug 41%) · 96% clinician	no trial data cached
Pneumonitis	35	13.5 9.7–18.8ROR 13.8 · χ² 394 / p 6e-88	13.2 EB05 9.7 · IC025 +3.0 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 9.6	no trial data cached
Disease progression	152	13.5 11.6–15.7ROR 14.5 · χ² 1,751 / p <1e-300	13.4 EB05 11.7 · IC025 +3.4 3/3 methods agree	Reporting / coding artifact	serious PRR 9.3 · 91% clinician	no trial data cached
Hypothyroidism	36	11.8 8.5–16.3ROR 12.0 · χ² 346 / p 2e-77	11.4 EB05 8.4 · IC025 +2.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.8 · ♀ 62% (drug 41%) · 94% clinician	no trial data cached
Metastases to lung	12	10.9 6.2–19.1ROR 10.9 · χ² 98 / p 2e-23	9.1 EB05 5.1 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 7.6	no trial data cached
Hyperthyroidism	15	10.8 6.5–17.9ROR 10.9 · χ² 124 / p 4e-29	9.5 EB05 5.7 · IC025 +2.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.1	no trial data cached
Interstitial lung disease	46	10.0 7.5–13.2ROR 10.2 · χ² 362 / p 5e-81	9.5 EB05 7.3 · IC025 +2.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 7.0 · ♀ 64% (drug 41%) · 98% clinician	no trial data cached
Basal cell carcinoma	13	8.7 5.1–15.0ROR 8.7 · χ² 81 / p 1e-19	7.2 EB05 4.3 · IC025 +1.8 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 6.2	no trial data cached
Hypercalcaemia	10	8.5 4.6–15.7ROR 8.5 · χ² 59 / p 1e-14	6.6 EB05 3.7 · IC025 +1.6 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.1	no trial data cached
Colitis	30	8.3 5.8–11.9ROR 8.4 · χ² 186 / p 1e-42	7.6 EB05 5.5 · IC025 +2.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.6	no trial data cached
Ischaemic stroke	14	8.2 4.9–13.8ROR 8.2 · χ² 81 / p 1e-19	6.8 EB05 4.2 · IC025 +1.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.7	no trial data cached
Hepatitis (liver inflammation)	20	8.2 5.3–12.6ROR 8.2 · χ² 119 / p 6e-28	7.2 EB05 4.8 · IC025 +2.0 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.8 · 90% clinician	no trial data cached
Toxic epidermal necrolysis (severe skin peeling reaction)	11	7.6 4.2–13.7ROR 7.7 · χ² 57 / p 2e-14	6.1 EB05 3.5 · IC025 +1.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.3	no trial data cached
Hepatocellular injury	10	7.3 4.0–13.6ROR 7.4 · χ² 49 / p 2e-12	5.8 EB05 3.3 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 5.1	no trial data cached
Rash maculo-papular	14	6.6 3.9–11.1ROR 6.6 · χ² 61 / p 3e-15	5.5 EB05 3.5 · IC025 +1.6 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 3.6	no trial data cached
Hepatotoxicity (liver damage)	14	6.6 3.9–11.1ROR 6.6 · χ² 61 / p 3e-15	5.5 EB05 3.5 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 4.7	no trial data cached
Skin lesion	17	6.5 4.1–10.5ROR 6.6 · χ² 74 / p 4e-18	5.6 EB05 3.7 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 4.5	no trial data cached
Transaminases increased	12	5.6 3.2–9.9ROR 5.7 · χ² 41 / p 6e-11	4.7 EB05 2.9 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.2	no trial data cached
Stevens-johnson syndrome (severe blistering skin reaction)	11	5.2 2.9–9.3ROR 5.2 · χ² 33 / p 5e-9	4.3 EB05 2.6 · IC025 +1.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 3.6	no trial data cached
Infusion related reaction (reaction during infusion)	31	4.9 3.5–7.0ROR 5.0 · χ² 93 / p 3e-22	4.6 EB05 3.4 · IC025 +1.6 3/3 methods agree	Labeled (related wording) related wording	serious PRR 2.5 · 90% clinician	no trial data cached
Neoplasm progression	16	4.8 2.9–7.8ROR 4.8 · χ² 44 / p 2e-11	4.2 EB05 2.8 · IC025 +1.3 3/3 methods agree	Labeled (related wording) related wording	serious PRR 4.0	no trial data cached

Trial evidence (ClinicalTrials.gov)

Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).

Most frequently reported reactions

By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Disease progression	152	13.5 11.6–15.7ROR 14.5 · χ² 1,751 / p <1e-300	13.4 EB05 11.7 · IC025 +3.4 3/3 methods agree	Reporting / coding artifact	serious PRR 9.3 · 91% clinician	no trial data cached
Myocarditis	49	45.4 34.4–59.9ROR 46.5 · χ² 2,074 / p <1e-300	44.5 EB05 35.0 · IC025 +4.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 31.0 · 94% clinician	no trial data cached
Interstitial lung disease	46	10.0 7.5–13.2ROR 10.2 · χ² 362 / p 5e-81	9.5 EB05 7.3 · IC025 +2.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 7.0 · ♀ 64% (drug 41%) · 98% clinician	no trial data cached
Hypothyroidism	36	11.8 8.5–16.3ROR 12.0 · χ² 346 / p 2e-77	11.4 EB05 8.4 · IC025 +2.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.8 · ♀ 62% (drug 41%) · 94% clinician	no trial data cached
Pneumonitis	35	13.5 9.7–18.8ROR 13.8 · χ² 394 / p 6e-88	13.2 EB05 9.7 · IC025 +3.0 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 9.6	no trial data cached
Infusion related reaction (reaction during infusion)	31	4.9 3.5–7.0ROR 5.0 · χ² 93 / p 3e-22	4.6 EB05 3.4 · IC025 +1.6 3/3 methods agree	Labeled (related wording) related wording	serious PRR 2.5 · 90% clinician	no trial data cached
Colitis	30	8.3 5.8–11.9ROR 8.4 · χ² 186 / p 1e-42	7.6 EB05 5.5 · IC025 +2.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.6	no trial data cached
Cholestasis (bile flow blockage)	26	14.2 9.7–20.9ROR 14.4 · χ² 307 / p 6e-69	13.8 EB05 9.6 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 10.0 · ♀ 14% (drug 41%) · 96% clinician	no trial data cached
Adrenal insufficiency	24	21.0 14.1–31.2ROR 21.2 · χ² 436 / p 4e-97	20.6 EB05 14.5 · IC025 +3.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 14.8	no trial data cached
Hepatic cytolysis	23	19.7 13.1–29.6ROR 19.9 · χ² 389 / p 7e-87	19.3 EB05 13.4 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 13.7 · ♀ 19% (drug 41%) · 96% clinician	no trial data cached
Hepatitis (liver inflammation)	20	8.2 5.3–12.6ROR 8.2 · χ² 119 / p 6e-28	7.2 EB05 4.8 · IC025 +2.0 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 5.8 · 90% clinician	no trial data cached
Skin lesion	17	6.5 4.1–10.5ROR 6.6 · χ² 74 / p 4e-18	5.6 EB05 3.7 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 4.5	no trial data cached
Neoplasm progression	16	4.8 2.9–7.8ROR 4.8 · χ² 44 / p 2e-11	4.2 EB05 2.8 · IC025 +1.3 3/3 methods agree	Labeled (related wording) related wording	serious PRR 4.0	no trial data cached
Squamous cell carcinoma	16	17.8 10.9–28.9ROR 17.9 · χ² 236 / p 1e-53	17.1 EB05 10.7 · IC025 +2.7 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 12.8	no trial data cached
Hyperthyroidism	15	10.8 6.5–17.9ROR 10.9 · χ² 124 / p 4e-29	9.5 EB05 5.7 · IC025 +2.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.1	no trial data cached

Unlabeled candidate signals

These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.

Hepatic cytolysis — n=23, PRR 19.7
Cholestasis — n=26, PRR 14.2

Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.

Common questions

What are the most reported side effects of Cemiplimab-Rwlc?

In FDA FAERS, the most frequently co-reported reaction terms for Cemiplimab-Rwlc are myocarditis, interstitial lung disease, hypothyroidism, pneumonitis, infusion related reaction, colitis. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.

Does Cemiplimab-Rwlc have an FDA boxed warning?

No. The FDA label retrieved for Cemiplimab-Rwlc has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Cemiplimab-Rwlc causes these side effects?

No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.

Sources & methods

FDA label via openFDA (set ID 4347ae1f-d397-4f18-8b70-03897e1c054a, effective 20260831; matched on openfda.generic_name.exact:"CEMIPLIMAB-RWLC")
Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA count= aggregation, field patient.drug.openfda.generic_name.exact, 41 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction
Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
Seriousness and sex counts from openFDA count=serious, patient.patientsex, seriousnessdeath

Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.