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trastuzumab

Sold as Herceptin. Class: HER2 (Human Epidermal Growth Factor Receptor 2) inhibitors. First FDA approval 09/25/1998: 28 years on the US market.

This grade answers one narrow question: how strong is the public evidence and safety record behind this drug, and how clean is its money trail and court record? It is not a verdict on whether the drug is right for you.

C

Score breakdown (73/100)

Safety ×35%
D
Evidence ×25%
A
Regulatory ×15%
A
Money & lawsuits ×15%
D
Options ×10%
C

Safety: 57

Evidence: 90

Regulatory history: 95

Money & lawsuits: 60

Options: 70

FDA boxed warning

WARNING: INTERSTITIAL LUNG DISEASE and EMBRYO-FETAL TOXICITY Interstitial Lung Disease (ILD) and pneumonitis, including severe, life-threatening, and fatal cases, have been reported with ENHERTU. Monitor for and promptly investigate signs and symptoms including cough, dyspnea, fever, and other new or worsening respiratory symptoms. Permanently discontinue ENHERTU in all patients with Grade 2 or higher ILD/pneumonitis. Advise patients of the risk and the need to immediately report symptoms [see Dosage and Administration (2.3) , Warnings and Precautions (5.1) ] . Embryo-Fetal Toxicity: Exposure to ENHERTU during pregnancy can cause embryo-fetal harm. Advise patients of these risks and the need for effective contraception [see Warnings and Precautions (5.4) , Use in Specific Populations (8.1 , 8.3) ] . WARNING: INTERSTITIAL LUNG DISEASE and EMBRYO-FETAL TOXICITY See full prescribing information for complete boxed warning. Interstitial lung disease (ILD) and pneumonitis, including severe, life threatening, and fatal cases, have been reported with ENHERTU. Monitor for and promptly investigate signs and symptoms including cough, dyspnea, fever, and other new or worsening respiratory symp...

Independent reviews and post-approval warnings

FDA Drug Safety Communications

Warnings the FDA chose to announce publicly after approval, as opposed to quiet label edits. Class-wide items name the drug's class, not this drug specifically.

WHO Essential Medicine

Listed on the WHO Model List of Essential Medicines: a global expert panel judged it among the medicines a health system should always have, on evidence of value, not marketing.

What the FDA label says

Approved uses

is a HER2-directed antibody and topoisomerase inhibitor conjugate indicated for: HER2-Positive Early Breast Cancer as neoadjuvant treatment of adult patients with HER2-positive (IHC 3+ or ISH+) Stage II or III breast cancer, as determined by an FDA-authorized test followed by a taxane, trastuzumab, and pertuzumab (THP). ( 1.1 ) as adjuvant treatment of adult patients with HER2-positive (IHC 3+ or ISH+) breast cancer who have residual invasive disease following neoadjuvant trastuzumab (with or without pertuzumab) and taxane-based treatment. ( 1.1 ) HER2-Positive Metastatic Breast Cancer in combination with pertuzumab as first-line treatment of adult patients with unresectable or metastatic HER2-positive (IHC 3+ or ISH+) breast cancer, as determined by an FDA-authorized test. ( 1.2 ) as monotherapy for the treatment of adult patients with unresectable or metastatic HER2-positive (IHC 3+ or ISH+) breast cancer who have received a prior anti-HER2-based regimen either in the metastatic setting, or, in the neoadjuvant or adjuvant setting and have developed disease recurrence during or within six months of completing therapy. ( 1.2 ) HER2-Low and HER2-Ultralow Metastatic Breast Cancer as ...

Contraindications

None . None. ( 4 )

Warnings and precautions

Neutropenia: Monitor complete blood counts prior to initiation of ENHERTU and prior to each dose, and as clinically indicated. Manage through treatment interruption or dose reduction. ( 2.3 , 5.2 ) Left Ventricular Dysfunction (LVD): Assess left ventricular ejection fraction (LVEF) prior to initiation of ENHERTU and at regular intervals during treatment as clinically indicated. Manage through treatment interruption or discontinuation. Permanently discontinue ENHERTU in patients with symptomatic congestive heart failure (CHF). ( 2.3 , 5.3 ) 5.1 Interstitial Lung Disease/Pneumonitis Severe, life-threatening, or fatal interstitial lung disease (ILD), including pneumonitis, can occur in patients treated with ENHERTU [see Adverse Reactions (6.1) ] . A higher incidence of Grade 1 and 2 ILD/pneumonitis has been observed in patients with moderate renal impairment. Advise patients to immediately report cough, dyspnea, fever, and/or any new or worsening respiratory symptoms. Monitor patients for signs and symptoms of ILD. Promptly investigate evidence of ILD. Evaluate patients with suspected ILD by radiographic imaging. Consider consultation with a pulmonologist. For asymptomatic (Grade 1) I...

Adverse reactions (label)

The following clinically significant adverse reactions are described elsewhere in the labeling: Interstitial Lung Disease/Pneumonitis [see Warnings and Precautions (5.1) ] Neutropenia [see Warnings and Precautions (5.2) ] Left Ventricular Dysfunction [see Warnings and Precautions (5.3) ] The most common adverse reactions (≥20%), including laboratory abnormalities, in patients with: HER2-Positive, HER2-Low, and HER2-Ultralow Breast Cancer, HER2-Mutant NSCLC, and HER2-Positive (including IHC 3+) Solid Tumors are decreased white blood cell count, nausea, decreased hemoglobin, decreased neutrophil count, decreased lymphocyte count, fatigue, decreased platelet count, increased aspartate aminotransferase, increased alanine aminotransferase, increased blood alkaline phosphatase, vomiting, alopecia, constipation, decreased blood potassium, decreased appetite, diarrhea, and musculoskeletal pain. ( 6.1 ) HER2-Positive Early Breast Cancer are decreased hemoglobin, increased alanine aminotransferase, increased aspartate aminotransferase, decreased white blood cell count, nausea, peripheral neuropathy, diarrhea, decreased neutrophil count, alopecia, fatigue, decreased lymphocyte count, rash, mu...

Recent major label changes

Indications and Usage ( 1.1 ) 05/2026 Indications and Usage ( 1.2 ) 12/2025 Dosage and Administration ( 2.1 , 2.2 , 2.3 ) 05/2026 Dosage and Administration ( 2.1 , 2.2 , 2.3 ) 12/2025 Warnings and Precautions ( 5.1 , 5.2 , 5.3 ) 05/2026 Warnings and Precautions ( 5.1 , 5.2 , 5.3 ) 12/2025

Source: FDA SPL label for Enhertu (Daiichi Sankyo Inc.), effective 20260515. Full label on DailyMed.

Side-effect reports sent to the FDA

These are counts of reports people filed, not rates of harm. Anyone can file one, and nobody checks whether the drug was the cause. Millions of doses are taken for every report sent, so the useful part is how this drug compares with the average across all drugs.

59,860reports that mention this drug
59,805of those blame this drug, not another one the person was taking
84%of reports describe a serious outcome, such as a hospital stay (average for all drugs: 57%)
11.4%of reports include a death, from any cause (average for all drugs: 9.1%)

Problems reported most often

Diarrhoea · 5,927Alopecia · 4,941Off Label Use · 4,475Nausea · 4,253Fatigue · 4,115Myelosuppression · 3,674Death · 2,964Disease Progression · 2,799Vomiting · 2,689Dyspnoea · 2,339Asthenia · 2,191Pyrexia · 2,143Neuropathy Peripheral · 2,012Neutropenia · 1,882Pain · 1,872

Reports per year

20192020202120222023202420252026
5,1175,5355,2984,9375,5757,9855,1242,354

Source: the FDA's Adverse Event Reporting System (FAERS). Reports are voluntary and unverified. Drugs that are prescribed a lot, in the news, or in lawsuits attract more reports, so the percentages are compared with the whole database to correct for that partly, not fully.

Recalls and regulatory record

0recall actions on file
0 / 0brand / generic applications
0label changes since 2021
NoREMS program

Evidence base

492randomized trials (PubMed)
164systematic reviews
1,746registered trials
59%of completed trials posted results
12%terminated or withdrawn
50%industry-funded

Independent Cochrane reviews

Counts measure how much evidence exists and how transparent it is, not how big the benefit is. For that, ask your prescriber: if 100 people like me took this, how many would get better because of it, and how many would be harmed? (Doctors call these the "number needed to treat" and "number needed to harm.") It differs by condition and is the number drug ads leave out. Sources: PubMed, ClinicalTrials.gov.

Money and lawsuits

In 2024, drug companies reported $5,875 in payments to US physicians and hospitals tied to this drug across 77 transactions (Herceptin $5,875).

Pending federal multidistrict litigation

Not named in any federal pharmaceutical settlement of $100M or more on record.

Sources: CMS Open Payments (Sunshine Act); Judicial Panel on Multidistrict Litigation pending docket list; DOJ settlements as tabulated on Wikipedia with links to the primary record. State-court and individual suits are not included.

Who takes it and what it costs

122Medicare Part D patients (2024)
919prescriptions filled
$5,107average cost per fill
$5Mtotal Medicare spend

Same-class alternatives

ado-trastuzumab emtansinemargetuximabtrastuzumab deruxtecanzanidatamab

Same ATC pharmacological class, graded ones first, best grade at the top. Being in the same class does not make them interchangeable for your condition; it makes them worth asking about.

Questions to ask your prescriber

  1. In 2013 the FDA issued a safety communication about this drug (FDA warns about potential medication errors resulting from confusion regarding nonproprietary name for breast ). Does that risk apply to me?
  2. This drug carries a boxed warning. Which specific risk does it cover, and does it apply to me?
  3. The most-reported problems in FDA's adverse event data are diarrhoea, alopecia, nausea. How would we recognize and handle those?
  4. Off-label use is among the most-reported items for this drug. Is my use on-label, and if not, what evidence supports it?
  5. Why this one over ado-trastuzumab emtansine, margetuximab, pertuzumab? What would make you pick one of those instead?
  6. There is no generic. Is there an older generic in the same class that works as well for my situation?
  7. This drug is in active federal litigation. What is the claim, and does it affect my risk?
  8. What result are we expecting, by when, and what is the plan if it does not happen?
  9. If 100 people like me took this drug, how many would actually get better because of it, and how many would be harmed by it? (Doctors call these the number needed to treat and the number needed to harm.)