Elranatamab-Bcmm side effects: what 1,037 FDA adverse event reports show

Elranatamab-Bcmm · Elrexfio · 17 reaction terms · 475 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Brand names

Elrexfio

openFDA label

Who reports

1,037 reports · 85% serious · 244 with death outcome · 52% female

openFDA FAERS counts, all years, deduplication not applied

Used for

ELREXFIO is indicated for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody. This indication is approved under accelerated approval based on response rate and durability of response .

FDA label, Indications and Usage

What it is

Elranatamab-bcmm is a bispecific B-cell maturation antigen (BCMA)-directed CD3 T-cell engager. It is a bispecific, humanized immunoglobulin 2-alanine (IgG2Δa) kappa antibody derived from two monoclonal antibodies (mAbs), an anti-BCMA mAb and an anti-CD3 mAb.

FDA label, Description section

Boxed warning

CYTOKINE RELEASE SYNDROME and NEUROLOGIC TOXICITY including IMMUNE EFFECTOR CELL-ASSOCIATED NEUROTOXICITY SYNDROME • Cytokine Release Syndrome (CRS), including life-threatening or fatal reactions, can occur in patients receiving ELREXFIO. Initiate treatment with ELREXFIO step-up dosing schedule to reduce the risk of CRS.

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 13 strongest signals

Labeled — boxed warning 2Labeled adverse reaction 3Labeled (related wording) 2Likely indication confounding 1Reporting / coding artifact 1Lab value / disease marker 1Not in label — unassessed 3

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.
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.
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. 4 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	184	197.2 172.8–225.0ROR 239.5 · χ² 35,400 / p <1e-300	191.4 EB05 169.3 · IC025 +6.8 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 132.3 · 95% clinician	no trial data cached
Cytomegalovirus infection	25	30.4 20.7–44.8ROR 31.2 · χ² 682 / p 1e-150	29.8 EB05 21.2 · IC025 +3.6 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 20.9 · 100% clinician	no trial data cached
Cytopenia	16	27.1 16.7–44.1ROR 27.5 · χ² 376 / p 4e-84	26.3 EB05 17.1 · IC025 +3.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 19.0	no trial data cached
Plasma cell myeloma	40	20.7 15.3–28.1ROR 21.5 · χ² 731 / p 2e-161	20.5 EB05 15.7 · IC025 +3.5 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 15.1 · 90% clinician	no trial data cached
Uveitis	11	16.5 9.2–29.7ROR 16.6 · χ² 145 / p 1e-33	15.2 EB05 8.0 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 11.9	no trial data cached
Malignant neoplasm progression	80	15.9 12.9–19.6ROR 17.1 · χ² 1,106 / p 8e-243	15.8 EB05 13.1 · IC025 +3.5 3/3 methods agree	Reporting / coding artifact	serious PRR 11.0 · 90% clinician	no trial data cached
Neoplasm progression	25	14.4 9.8–21.2ROR 14.7 · χ² 299 / p 3e-67	14.0 EB05 9.6 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 8.1	no trial data cached
Neurotoxicity	11	12.8 7.1–23.1ROR 12.9 · χ² 108 / p 1e-25	11.1 EB05 5.8 · IC025 +2.1 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 8.8	no trial data cached
Injection site rash	12	8.0 4.6–14.0ROR 8.1 · χ² 67 / p 2e-16	6.5 EB05 3.8 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious n=8	no trial data cached
Full blood count decreased	7	7.0 3.4–14.7ROR 7.1 · χ² 30 / p 2e-8	5.1 EB05 2.6 · IC025 +1.0 3/3 methods agree	Lab value / disease marker	serious PRR 5.9	no trial data cached
Skin exfoliation	27	6.6 4.5–9.5ROR 6.7 · χ² 122 / p 9e-29	6.0 EB05 4.3 · IC025 +1.9 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 4.9 · ♀ 72% (drug 52%)	no trial data cached
Myelosuppression	8	4.8 2.4–9.5ROR 4.8 · χ² 20 / p 4e-6	3.8 EB05 2.1 · IC025 +0.7 3/3 methods agree	Not in label — unassessed	serious PRR 3.2	no trial data cached
Injection site erythema (redness where injected)	15	2.5 1.5–4.1ROR 2.5 · χ² 12 / p 3e-4	2.3 EB05 1.5 · IC025 +0.4	Labeled (related wording) related wording	serious PRR 8.8	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	184	197.2 172.8–225.0ROR 239.5 · χ² 35,400 / p <1e-300	191.4 EB05 169.3 · IC025 +6.8 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 132.3 · 95% clinician	no trial data cached
Malignant neoplasm progression	80	15.9 12.9–19.6ROR 17.1 · χ² 1,106 / p 8e-243	15.8 EB05 13.1 · IC025 +3.5 3/3 methods agree	Reporting / coding artifact	serious PRR 11.0 · 90% clinician	no trial data cached
Plasma cell myeloma	40	20.7 15.3–28.1ROR 21.5 · χ² 731 / p 2e-161	20.5 EB05 15.7 · IC025 +3.5 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 15.1 · 90% clinician	no trial data cached
Skin exfoliation	27	6.6 4.5–9.5ROR 6.7 · χ² 122 / p 9e-29	6.0 EB05 4.3 · IC025 +1.9 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 4.9 · ♀ 72% (drug 52%)	no trial data cached
Neoplasm progression	25	14.4 9.8–21.2ROR 14.7 · χ² 299 / p 3e-67	14.0 EB05 9.6 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 8.1	no trial data cached
Cytomegalovirus infection	25	30.4 20.7–44.8ROR 31.2 · χ² 682 / p 1e-150	29.8 EB05 21.2 · IC025 +3.6 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 20.9 · 100% clinician	no trial data cached
Cytopenia	16	27.1 16.7–44.1ROR 27.5 · χ² 376 / p 4e-84	26.3 EB05 17.1 · IC025 +3.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 19.0	no trial data cached
Injection site erythema (redness where injected)	15	2.5 1.5–4.1ROR 2.5 · χ² 12 / p 3e-4	2.3 EB05 1.5 · IC025 +0.4	Labeled (related wording) related wording	serious PRR 8.8	no trial data cached
Injection site rash	12	8.0 4.6–14.0ROR 8.1 · χ² 67 / p 2e-16	6.5 EB05 3.8 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious n=8	no trial data cached
Neurotoxicity	11	12.8 7.1–23.1ROR 12.9 · χ² 108 / p 1e-25	11.1 EB05 5.8 · IC025 +2.1 3/3 methods agree	Labeled — boxed warning exact term	serious PRR 8.8	no trial data cached
Uveitis	11	16.5 9.2–29.7ROR 16.6 · χ² 145 / p 1e-33	15.2 EB05 8.0 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 11.9	no trial data cached
Myelosuppression	8	4.8 2.4–9.5ROR 4.8 · χ² 20 / p 4e-6	3.8 EB05 2.1 · IC025 +0.7 3/3 methods agree	Not in label — unassessed	serious PRR 3.2	no trial data cached
Full blood count decreased	7	7.0 3.4–14.7ROR 7.1 · χ² 30 / p 2e-8	5.1 EB05 2.6 · IC025 +1.0 3/3 methods agree	Lab value / disease marker	serious PRR 5.9	no trial data cached
Injection site irritation	4	6.4 2.4–17.0ROR 6.4 · χ² 13 / p 1e-4	4.1 EB05 1.8 · IC025 +0.2	Labeled (related wording) related wording	serious n=1	no trial data cached
Hepatic cytolysis	4	6.6 2.5–17.6ROR 6.6 · χ² 14 / p 1e-4	4.2 EB05 1.8 · IC025 +0.3	Not in label — unassessed	serious PRR 4.5	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.

Neoplasm progression — n=25, PRR 14.4

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 Elranatamab-Bcmm?

In FDA FAERS, the most frequently co-reported reaction terms for Elranatamab-Bcmm are cytokine release syndrome, plasma cell myeloma, skin exfoliation, neoplasm progression, cytomegalovirus infection, cytopenia. 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 Elranatamab-Bcmm have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: CYTOKINE RELEASE SYNDROME and NEUROLOGIC TOXICITY including IMMUNE EFFECTOR CELL-ASSOCIATED NEUROTOXICITY SYNDROME • Cytokine Release Syndrome (CRS), including life-threatening or fatal reactions, can occur in patients receiving ELREXFIO. Initiate treatment with ELREXFIO step-up dosing schedule to reduce the risk of CRS.

Do FAERS signals prove that Elranatamab-Bcmm 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 aa044060-5b4b-4692-bf0f-9a50e140b10e, effective 20260514; matched on openfda.generic_name.exact:"ELRANATAMAB-BCMM")
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, 17 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.