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The first targeted antibody for a solid tumour (1998), which turned HER2-positive breast cancer from the worst subtype into one of the most treatable.
Trastuzumab is a humanised IgG1 antibody that binds domain IV of HER2, blocking receptor signalling and recruiting immune cells through ADCC. It was the first targeted antibody for a solid tumour, approved for HER2-positive metastatic breast cancer in 1998, as adjuvant therapy in 2006 (HERA, NSABP B-31/N9831, about a 37% reduction in death) and for HER2-positive gastric cancer in 2010. Dual blockade with pertuzumab (CLEOPATRA, APHINITY) and the subcutaneous Phesgo built on it, and it is the antibody backbone of the conjugates T-DM1 and T-DXd. Adjuvant treatment lasts 1 year, and cardiomyopathy requires LVEF monitoring. Biosimilars since 2017 have cut cost worldwide, and whether shorter adjuvant courses are safe for lower-risk patients remains debated. For a newcomer: the drug that turned the worst breast cancer subtype into one of the most treatable.
Backbone ribbon from PDB 1N8Z. RCSB PDB 1N8Z. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
Humanised IgG1 binding HER2 ECD4; signal inhibition and ADCC. Connects to HER2.
1.Antibody binds domain IV of HER2
Source: www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications. Doses are for orientation; the current label governs.
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies. HCPCS J9355 for Herceptin; each biosimilar has its own Q-code. Under the Inflation Reduction Act, Part B coinsurance on a biosimilar is calculated on the reference product's price, so biosimilars usually cost the patient less.
Most commercial plans and PBM medical-benefit programmes now require a preferred trastuzumab biosimilar (e.g. Kanjinti, Ogivri, Trazimera) before the originator; prior authorisation confirms HER2 status.
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B) · FDA: Biosimilars. Not medical or financial advice; verify with your plan.
Sources: NICE TA34 · SMC advice: trastuzumab. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
The template for oncology biosimilar competition: five US entrants within a year.
HER2+ metastatic breast cancer: first targeted antibody for a solid tumour source
Adjuvant HER2+ early breast cancer (HERA, NSABP B-31/N9831) source
HER2+ metastatic gastric cancer (ToGA) source
First trastuzumab biosimilar (Ogivri) source
Subcutaneous trastuzumab-hyaluronidase (Herceptin Hylecta) source
Phesgo (pertuzumab, trastuzumab, hyaluronidase) subcutaneous source
FDA approves palbociclib with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of HR-positive, HER2-positive metastatic breast cancer source
| Region | Year | Indication |
|---|---|---|
| US | 1998 | HER2+ metastatic breast cancer |
| US | 2006 | Adjuvant HER2+ breast cancer |
| US | 2010 | HER2+ gastric cancer |
| Adverse event |
|---|
| Cardiomyopathy / LVEF decline |
| Infusion reactions |
| Fever |
| Nausea |
| Diarrhoea |
| Pulmonary toxicity (rare) |
Adjuvant trials: ~2-4% symptomatic heart failure with anthracyclines. Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
Read for the class this product belongs to (her2 antibodies) unless the answer names the product. Population figures from the cohorts named, not a prediction for one person. Blank where no source gives a recovery figure.
| Country | Reimbursement | List price | Assistance |
|---|---|---|---|
| United Statesgeneric | Medicare Part B; five biosimilars available since 2019, roughly 15-35% below reference price | not disclosed | genentech-access.com |
| United Kingdom | NICE: standard of care; biosimilars widely used | not disclosed | - |
List prices are manufacturer or Medicare figures where publicly disclosed; net prices after rebates are usually lower. Reimbursement changes; check the payer.
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HER2 immunohistochemistry is now worth doing in advanced gynaecological and other cancers, since trastuzumab deruxtecan is approved for HER2 3+ solid tumours after prior therapy.
One person, one tumour, one report, and it is not evidence that anyone should treat themselves. What it does contribute is unusually well documented: serial imaging through the course, a baseline biopsy and an excised specimen scored by the same pathology department, antibody titres, and a named protocol with doses. The design choices are the interesting part. Two different viruses in sequence to stay ahead of the antiviral antibody response, frequent dosing to keep infectious virus concentrated in the tumour, and the neoadjuvant setting rather than the late metastatic setting in which oncolytic viruses are normally tested. The result also cannot be attributed to the viruses alone: the tumour was surgically removed and a year of trastuzumab followed, and the phenotype change to HER2 3+ is itself a plausible reason the disease behaved differently this time.
Trastuzumab deruxtecan 5.4 mg/kg is the approved regimen for HER2-mutant lung cancer after platinum chemotherapy, and the trial is a rare example of dose optimisation improving safety without losing efficacy.
Pembrolizumab with trastuzumab and chemotherapy is the first-line standard for HER2-positive gastric cancer with a PD-L1 combined positive score of 1 or more.
The first United States approval of a HER2-directed regimen in colorectal cancer, and the basis for MOUNTAINEER-03, which is testing the combination with chemotherapy in the first line.
HER2 mutations, present in about 3 percent of lung adenocarcinomas, became actionable; trastuzumab deruxtecan received the first approval for a HER2-mutant lung cancer, at the lower 5.4 mg/kg dose validated in DESTINY-Lung02.
Trastuzumab deruxtecan is an option for active HER2-positive brain metastases, complementing tucatinib-based therapy, and challenges the assumption that antibody-drug conjugates cannot reach the brain.
It is the proof that plasma genotyping can enrol patients for a targeted colorectal trial, which matters most for a 2 to 3% alteration where archival tissue is often exhausted or out of date.
Query for this drug: (TITLE:"Trastuzumab" OR ABSTRACT:"Trastuzumab" OR TITLE:"Herceptin" OR ABSTRACT:"Herceptin" OR TITLE:"and biosimilars" OR ABSTRACT:"and biosimilars" OR TITLE:"Phesgo with pertuzumab" OR ABSTRACT:"Phesgo with pertuzumab" OR TITLE:"Trastuzumab and Hyaluronidase-oysk" OR ABSTRACT:"Trastuzumab and Hyaluronidase-oysk" OR TITLE:"Herceptin Hylecta" OR ABSTRACT:"Herceptin Hylecta") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Trastuzumab, not a curated reading list.
Shares A Safety and Efficacy Extension Study of Pertuzumab in Patients With Solid Tumors Previously Enrolled in a Hoffmann-La Roche-Sponsored Pertuzumab Clinical Trial, Optimization of Dynamic Neoadjuvant Therapy Strategies for HER2-Positive Breast Cancer Based on HER2-PET/CT Molecular Imaging, APHINITY: adjuvant pertuzumab added to trastuzumab and chemotherapy in early HER2-positive breast cancer, Early FDG-PET response → chemotherapy omission (HER2+).
Shares DESTINY-Lung01: trastuzumab deruxtecan in HER2-mutant non-small-cell lung cancer, DESTINY-Lung02: two doses of trastuzumab deruxtecan in HER2-mutant metastatic non-small-cell lung cancer, DESTINY-Gastric01: trastuzumab deruxtecan in previously treated HER2-positive gastric cancer, Study of AZD9574 as Monotherapy and in Combination With Anti-cancer Agents in Participants With Advanced Solid Malignancies.
Shares Tucatinib + trastuzumab + capecitabine for brain metastases, HER2CLIMB brain metastases analysis: intracranial efficacy and survival with tucatinib, HER2CLIMB: tucatinib with trastuzumab and capecitabine for HER2-positive metastatic breast cancer, including brain metastases, A Study of Tucatinib and Trastuzumab in People With Rectal Cancer.
Shares A Safety Extension Study of Trastuzumab Emtansine in Participants Previously Treated With Trastuzumab Emtansine Alone or in Combination With Other Anti-Cancer Therapy in One of the Parent Studies, A Study Evaluating the Efficacy and Safety of Adjuvant Atezolizumab or Placebo and Trastuzumab Emtansine for Participants With HER2-Positive Breast Cancer at High Risk of Recurrence Following Preoperative Therapy, ATEMPT, A Study to Investigate Safety and Tolerability of TransCon IL-2 β/γ Alone or in Combination With Pembrolizumab and/or TransCon TLR7/8 Agonist or Other.
Shares Epitope, HER2 sequence in gastric cancer: zanidatamab/trastuzumab + chemo ± PD-1 → T-DXd, A Phase 2 Neoadjuvant Study of Zanidatamab in Combination With Chemotherapy in Participants With HER2-positive Breast Cancer, A Study Comparing the Efficacy and Safety of Zanidatamab to Trastuzumab, Each in Combination With Physician's Choice Chemotherapy, for the Treatment o.
Shares A Study of DB-1310 in Advanced/Metastatic Solid Tumors, A Study of HRS-4508 in Combination With Other Anti-tumor Therapy for Solid Tumor, RC48 Combined With Chemotherapy in HER2-Positive Advanced Breast Cancer Patients With Prior TOP1i-ADC Failure, Safety and Efficacy of HCB101 in Combination With Multiple Agents in Patients With Advanced Solid Tumors.
Shares Radiation Therapy With or Without Trastuzumab in Treating Women With Ductal Carcinoma In Situ Who Have Undergone Lumpectomy, Chemotherapy With or Without Trastuzumab After Surgery in Treating Women With Invasive Breast Cancer, Make the biosimilar the default at the pharmacy for trastuzumab, bevacizumab and rituximab, Docetaxel, Carboplatin, Trastuzumab, and Pertuzumab With or Without Estrogen Deprivation in Treating Patients With Hormone Receptor-Positive, HER2-Positive Operable or Locally Advanced Breast Cancer.
Shares A Study of Tucatinib and Trastuzumab in People With Rectal Cancer, A Study of Tucatinib (MK-7119) in Combination With Trastuzumab and Capecitabine in Participants With Previously Treated Locally Advanced Unresectable or Metastatic Human Epidermal Growth Factor Receptor 2 Positive (HER2+) Breast Carcinoma (MK-7119-001), HER2CLIMB-05, Tucatinib+Trastuzumab+Eribulin in HER2+ MBC.