Tazemetostat side effects: what 1,592 FDA adverse event reports show

Tazemetostat · Tazverik · 23 reaction terms · 971 drug–reaction co-reports · data 2026-09-14

Drug class

Methyltransferase inhibitor

FDA label, Indications wording

Brand names

Tazverik

openFDA label

Who reports

1,592 reports · 44% serious · 209 with death outcome · 46% female

openFDA FAERS counts, all years, deduplication not applied

Used for

TAZVERIK is a methyltransferase inhibitor indicated for the treatment of: Adults and pediatric patients aged 16 years and older with metastatic or locally advanced epithelioid sarcoma not eligible for complete resection. ( 1.1 ) Adult patients with rel.

FDA label, Indications and Usage

What it is

Tazemetostat is a methyltransferase inhibitor. Tazemetostat hydrobromide has the following chemical name: [1,1'-Biphenyl]-3-carboxamide, N -[(1,2-dihydro-4,6-dimethyl-2-oxo-3-pyridinyl)methyl]-5-[ethyl(tetrahydro-2 H -pyran-4-yl)amino]-4-methyl-4'-(4-morpholinylmethyl)-, hydrobromide (1:1).

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 16 strongest signals

Labeled adverse reaction 3Labeled (related wording) 2Reporting / coding artifact 4Lab value / disease marker 4Not in label — unassessed 3

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.
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.
Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
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. 7 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
Taste disorder	52	34.1 26.1–44.6ROR 35.2 · χ² 1,637 / p <1e-300	33.7 EB05 26.7 · IC025 +4.2 3/3 methods agree	Not in label — unassessed	serious PRR 26.0 · ♀ 67% (drug 46%)	no trial data cached
Disease progression	305	34.0 30.8–37.6ROR 41.8 · χ² 9,773 / p <1e-300	33.9 EB05 30.8 · IC025 +4.8 3/3 methods agree	Reporting / coding artifact	serious PRR 22.7	no trial data cached
Full blood count abnormal	10	12.5 6.7–23.1ROR 12.5 · χ² 94 / p 1e-22	10.4 EB05 5.3 · IC025 +1.9 3/3 methods agree	Lab value / disease marker	serious PRR 13.1	no trial data cached
Myelodysplastic syndrome	13	11.8 6.9–20.3ROR 11.9 · χ² 118 / p 9e-28	10.3 EB05 5.8 · IC025 +2.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 15.7	no trial data cached
Blood lactate dehydrogenase increased	12	9.9 5.6–17.4ROR 9.9 · χ² 87 / p 5e-21	8.1 EB05 4.6 · IC025 +1.9 3/3 methods agree	Lab value / disease marker	serious PRR 12.7	no trial data cached
Product dose omission issue	212	9.8 8.6–11.1ROR 11.1 · χ² 1,683 / p <1e-300	9.7 EB05 8.6 · IC025 +3.0 3/3 methods agree	Reporting / coding artifact	serious PRR 14.7 · 76% consumer	no trial data cached
Lymphadenopathy	21	7.8 5.1–11.9ROR 7.9 · χ² 118 / p 1e-27	6.9 EB05 4.7 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	no trial data cached
Red blood cell count decreased	16	7.3 4.5–11.9ROR 7.4 · χ² 81 / p 9e-20	6.2 EB05 4.0 · IC025 +1.8 3/3 methods agree	Lab value / disease marker	serious PRR 8.0	no trial data cached
Platelet count decreased	53	6.5 5.0–8.5ROR 6.7 · χ² 244 / p 3e-55	6.2 EB05 4.9 · IC025 +2.2 3/3 methods agree	Labeled (related wording) related wording	serious PRR 6.3	no trial data cached
Oral pain	11	6.4 3.6–11.6ROR 6.5 · χ² 45 / p 9e-12	5.2 EB05 3.1 · IC025 +1.4 3/3 methods agree	Labeled (related wording) related wording	serious PRR 9.9	no trial data cached
Bone pain	26	5.8 4.0–8.5ROR 5.9 · χ² 99 / p 1e-23	5.3 EB05 3.8 · IC025 +1.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.1 · 88% consumer	no trial data cached
Covid-19	72	5.3 4.3–6.7ROR 5.5 · χ² 252 / p 5e-57	5.2 EB05 4.2 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 6.7	no trial data cached
Neutrophil count decreased	16	5.2 3.2–8.4ROR 5.2 · χ² 50 / p 8e-13	4.6 EB05 3.0 · IC025 +1.4 3/3 methods agree	Lab value / disease marker	serious PRR 5.5	no trial data cached
Intentional dose omission	10	4.8 2.6–8.9ROR 4.8 · χ² 26 / p 1e-7	4.0 EB05 2.4 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	serious PRR 2.6	no trial data cached
Alopecia (hair loss)	69	4.6 3.7–5.8ROR 4.8 · χ² 193 / p 4e-44	4.5 EB05 3.7 · IC025 +1.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 3.0 · 74% consumer	no trial data cached
Malignant neoplasm progression	34	4.4 3.1–6.1ROR 4.5 · χ² 86 / p 1e-20	4.2 EB05 3.1 · IC025 +1.5 3/3 methods agree	Reporting / coding artifact	serious PRR 5.9	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	305	34.0 30.8–37.6ROR 41.8 · χ² 9,773 / p <1e-300	33.9 EB05 30.8 · IC025 +4.8 3/3 methods agree	Reporting / coding artifact	serious PRR 22.7	no trial data cached
Product dose omission issue	212	9.8 8.6–11.1ROR 11.1 · χ² 1,683 / p <1e-300	9.7 EB05 8.6 · IC025 +3.0 3/3 methods agree	Reporting / coding artifact	serious PRR 14.7 · 76% consumer	no trial data cached
Covid-19	72	5.3 4.3–6.7ROR 5.5 · χ² 252 / p 5e-57	5.2 EB05 4.2 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 6.7	no trial data cached
Alopecia (hair loss)	69	4.6 3.7–5.8ROR 4.8 · χ² 193 / p 4e-44	4.5 EB05 3.7 · IC025 +1.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 3.0 · 74% consumer	no trial data cached
Platelet count decreased	53	6.5 5.0–8.5ROR 6.7 · χ² 244 / p 3e-55	6.2 EB05 4.9 · IC025 +2.2 3/3 methods agree	Labeled (related wording) related wording	serious PRR 6.3	no trial data cached
Taste disorder	52	34.1 26.1–44.6ROR 35.2 · χ² 1,637 / p <1e-300	33.7 EB05 26.7 · IC025 +4.2 3/3 methods agree	Not in label — unassessed	serious PRR 26.0 · ♀ 67% (drug 46%)	no trial data cached
Malignant neoplasm progression	34	4.4 3.1–6.1ROR 4.5 · χ² 86 / p 1e-20	4.2 EB05 3.1 · IC025 +1.5 3/3 methods agree	Reporting / coding artifact	serious PRR 5.9	no trial data cached
Bone pain	26	5.8 4.0–8.5ROR 5.9 · χ² 99 / p 1e-23	5.3 EB05 3.8 · IC025 +1.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.1 · 88% consumer	no trial data cached
Lymphadenopathy	21	7.8 5.1–11.9ROR 7.9 · χ² 118 / p 1e-27	6.9 EB05 4.7 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	no trial data cached
Neutrophil count decreased	16	5.2 3.2–8.4ROR 5.2 · χ² 50 / p 8e-13	4.6 EB05 3.0 · IC025 +1.4 3/3 methods agree	Lab value / disease marker	serious PRR 5.5	no trial data cached
Red blood cell count decreased	16	7.3 4.5–11.9ROR 7.4 · χ² 81 / p 9e-20	6.2 EB05 4.0 · IC025 +1.8 3/3 methods agree	Lab value / disease marker	serious PRR 8.0	no trial data cached
Myelodysplastic syndrome	13	11.8 6.9–20.3ROR 11.9 · χ² 118 / p 9e-28	10.3 EB05 5.8 · IC025 +2.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 15.7	no trial data cached
Blood lactate dehydrogenase increased	12	9.9 5.6–17.4ROR 9.9 · χ² 87 / p 5e-21	8.1 EB05 4.6 · IC025 +1.9 3/3 methods agree	Lab value / disease marker	serious PRR 12.7	no trial data cached
Oral pain	11	6.4 3.6–11.6ROR 6.5 · χ² 45 / p 9e-12	5.2 EB05 3.1 · IC025 +1.4 3/3 methods agree	Labeled (related wording) related wording	serious PRR 9.9	no trial data cached
Intentional dose omission	10	4.8 2.6–8.9ROR 4.8 · χ² 26 / p 1e-7	4.0 EB05 2.4 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	serious PRR 2.6	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.

Taste disorder — n=52, PRR 34.1
Lymphadenopathy — n=21, PRR 7.8
Covid-19 — n=72, PRR 5.3

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 Tazemetostat?

In FDA FAERS, the most frequently co-reported reaction terms for Tazemetostat are covid-19, alopecia, platelet count decreased, taste disorder, bone pain, lymphadenopathy. 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 Tazemetostat have an FDA boxed warning?

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

Do FAERS signals prove that Tazemetostat 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 7db07b5f-4e22-467c-9c0a-f830b08dbb1d, effective 20260429; matched on openfda.generic_name.exact:"TAZEMETOSTAT")
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, 23 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.