Tebentafusp side effects: what 581 FDA adverse event reports show

Tebentafusp · Kimmtrak · 12 reaction terms · 361 drug–reaction co-reports · data 2026-09-14

Drug class

Bispecific gp100 Peptide-HLA-directed CD3 T Cell Engager

FDA label (Established Pharmacologic Class)

Brand names

Kimmtrak

openFDA label

Who reports

581 reports · 75% serious · 102 with death outcome · 51% female

openFDA FAERS counts, all years, deduplication not applied

Used for

KIMMTRAK is indicated for the treatment of HLA-A02:01-positive adult patients with unresectable or metastatic uveal melanoma. KIMMTRAK is a bispecific gp100 peptide-HLA-directed CD3 T cell engager indicated for the treatment of HLA-A02:01-positive adult patients with unresectable or metastatic uveal melanoma ( 1 , 2.1 ).

FDA label, Indications and Usage

What it is

Tebentafusp-tebn is a bispecific gp100 peptide-HLA-directed T cell receptor CD3 T cell engager. Tebentafusp-tebn has an approximate molecular weight of 77 kDa. Tebentafusp-tebn is produced by recombinant DNA technology in Escherichia coli cells.

FDA label, Description section

Boxed warning

CYTOKINE RELEASE SYNDROME Cytokine Release Syndrome (CRS), which may be serious or life-threatening, occurred in patients receiving KIMMTRAK. Monitor for at least 16 hours following first three infusions and then as clinically indicated [(see Dosage and Administration (2.2) , see Warnings and Precautions (5.1) ] .

FDA 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 10 strongest signals

Labeled — boxed warning 2Reporting / coding artifact 2Not in label — unassessed 6

What the badges mean

Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
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. 2 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
Cytokine release syndrome	115	219.1 185.9–258.3ROR 273.0 · χ² 24,626 / p <1e-300	210.2 EB05 179.9 · IC025 +6.5 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 147.7 · 94% clinician	no trial data cached
Tachypnoea	11	29.3 16.3–52.7ROR 29.9 · χ² 273 / p 1e-61	28.0 EB05 16.5 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious PRR 20.9	no trial data cached
Disease progression	72	22.0 17.8–27.4ROR 25.0 · χ² 1,433 / p <1e-300	21.9 EB05 18.0 · IC025 +3.9 3/3 methods agree	Reporting / coding artifact	serious PRR 13.8 · 96% clinician	no trial data cached
Malignant neoplasm progression	60	21.3 16.7–27.0ROR 23.6 · χ² 1,144 / p 5e-251	21.1 EB05 17.0 · IC025 +3.8 3/3 methods agree	Reporting / coding artifact	serious PRR 16.6	no trial data cached
Hair colour changes	7	20.1 9.6–42.0ROR 20.3 · χ² 109 / p 1e-25	17.7 EB05 7.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious n=4	no trial data cached
Chills	57	17.5 13.7–22.4ROR 19.3 · χ² 876 / p 7e-193	17.4 EB05 13.9 · IC025 +3.5 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 17.8 · ♀ 31% (drug 51%)	no trial data cached
Metastases to liver	8	16.5 8.3–32.8ROR 16.7 · χ² 101 / p 4e-24	14.3 EB05 6.3 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 12.7	no trial data cached
Neoplasm progression	14	14.4 8.6–24.2ROR 14.7 · χ² 162 / p 3e-37	13.3 EB05 7.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 15.2	no trial data cached
Metastases to central nervous system	5	14.1 5.9–33.7ROR 14.2 · χ² 48 / p 2e-12	9.7 EB05 3.5 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 10.9	no trial data cached
Metastases to bone	5	11.0 4.6–26.4ROR 11.1 · χ² 36 / p 9e-10	7.1 EB05 2.9 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 8.5	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
Cytokine release syndrome	115	219.1 185.9–258.3ROR 273.0 · χ² 24,626 / p <1e-300	210.2 EB05 179.9 · IC025 +6.5 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 147.7 · 94% clinician	no trial data cached
Disease progression	72	22.0 17.8–27.4ROR 25.0 · χ² 1,433 / p <1e-300	21.9 EB05 18.0 · IC025 +3.9 3/3 methods agree	Reporting / coding artifact	serious PRR 13.8 · 96% clinician	no trial data cached
Malignant neoplasm progression	60	21.3 16.7–27.0ROR 23.6 · χ² 1,144 / p 5e-251	21.1 EB05 17.0 · IC025 +3.8 3/3 methods agree	Reporting / coding artifact	serious PRR 16.6	no trial data cached
Chills	57	17.5 13.7–22.4ROR 19.3 · χ² 876 / p 7e-193	17.4 EB05 13.9 · IC025 +3.5 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 17.8 · ♀ 31% (drug 51%)	no trial data cached
Neoplasm progression	14	14.4 8.6–24.2ROR 14.7 · χ² 162 / p 3e-37	13.3 EB05 7.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 15.2	no trial data cached
Tachypnoea	11	29.3 16.3–52.7ROR 29.9 · χ² 273 / p 1e-61	28.0 EB05 16.5 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious PRR 20.9	no trial data cached
Metastases to liver	8	16.5 8.3–32.8ROR 16.7 · χ² 101 / p 4e-24	14.3 EB05 6.3 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 12.7	no trial data cached
Hair colour changes	7	20.1 9.6–42.0ROR 20.3 · χ² 109 / p 1e-25	17.7 EB05 7.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious n=4	no trial data cached
Metastases to bone	5	11.0 4.6–26.4ROR 11.1 · χ² 36 / p 9e-10	7.1 EB05 2.9 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 8.5	no trial data cached
Metastases to central nervous system	5	14.1 5.9–33.7ROR 14.2 · χ² 48 / p 2e-12	9.7 EB05 3.5 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 10.9	no trial data cached
Acute myeloid leukaemia	4	9.3 3.5–24.6ROR 9.3 · χ² 22 / p 1e-6	5.4 EB05 2.2 · IC025 +0.5 3/3 methods agree	Not in label — unassessed	serious PRR 7.1	no trial data cached
Product preparation error	3	5.2 1.7–16.2ROR 5.3 · χ² 6 / p 0.005	3.3 EB05 1.3 · IC025 -0.4 PRR-only: not supported by EBGM or IC	Reporting / coding artifact	–	no trial data cached

Unlabeled candidate signals

Every screened signal with n ≥ 20 was either labeled, an indication term, or an artifact pattern — no unlabeled candidate stood out in the top signals.

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 Tebentafusp?

In FDA FAERS, the most frequently co-reported reaction terms for Tebentafusp are cytokine release syndrome, chills, neoplasm progression, tachypnoea, metastases to liver, hair colour changes. 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 Tebentafusp have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: CYTOKINE RELEASE SYNDROME Cytokine Release Syndrome (CRS), which may be serious or life-threatening, occurred in patients receiving KIMMTRAK. Monitor for at least 16 hours following first three infusions and then as clinically indicated [(see Dosage and Administration (2.2) , see Warnings and Precautions (5.1) ] .

Do FAERS signals prove that Tebentafusp 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 24a49f57-d2fc-4ffe-9eb1-fe0460c6b067, effective 20260820; matched on openfda.generic_name.exact:"TEBENTAFUSP")
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, 12 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.