# Trastuzumab emtansine

Source: https://onco.cc/drugs/trastuzumab-emtansine/  
OnCo record `trastuzumab-emtansine` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Trastuzumab emtansine (Kadcyla, T-DM1) was the first ADC for a solid tumour (2013). It is still standard after surgery for HER2+ breast cancer patients whose tumour did not fully respond to pre-surgery treatment.

## Summary

Approved 2013 for pretreated HER2+ metastatic breast cancer (EMILIA) and 2019 for residual disease after neoadjuvant therapy (KATHERINE: invasive DFS HR 0.50, with OS benefit). Non-cleavable linker means no bystander effect, which explains its inferiority to T-DXd in DESTINY-Breast03 and its failure in HER2-low disease. Being displaced post-neoadjuvantly by T-DXd (DESTINY-Breast05).

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-04
- Brand: Kadcyla
- Code: T-DM1
- Modality: ADC
- Mechanism: Trastuzumab with lysine-conjugated DM1; released as Lys-MCC-DM1 after lysosomal degradation, cell-impermeable.
- Payload: DM1 (maytansinoid, tubulin inhibitor), DAR ~3.5
- Linker: SMCC, non-cleavable
- Approvals: US 2013: HER2+ metastatic breast cancer after trastuzumab and taxane; US 2019: Adjuvant HER2+ breast cancer with residual disease after neoadjuvant therapy
- Dosing: IV infusion; 3.6 mg/kg every 3 weeks; 14 cycles in the adjuvant setting
- Toxicity (grade 3+): Thrombocytopenia 6%

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Trastuzumab_emtansine
- FDA label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Trastuzumab%20emtansine

## Connected records

- biomarkers: [HER2 IHC 3+ (HER2-positive by immunohistochemistry)](https://onco.cc/biomarkers/her2-ihc-3-plus/), [HER2 ISH amplified (ERBB2 gene amplification)](https://onco.cc/biomarkers/her2-ish-amplified/)
- cancers: [Early HER2-positive breast cancer](https://onco.cc/cancers/her2-positive-early-breast-cancer/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HER2-positive breast cancer with brain metastases](https://onco.cc/cancers/her2-positive-breast-brain-metastases/), [Inflammatory breast cancer](https://onco.cc/cancers/inflammatory-breast-cancer/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/)
- targets: [HER2](https://onco.cc/targets/her2/)
- companies: [NSABP Foundation](https://onco.cc/companies/nsabp-foundation/), [Roche / Genentech](https://onco.cc/companies/roche-genentech/)
- terms: [DM1](https://onco.cc/terms/dm1/), [SMCC (thioether, non-cleavable)](https://onco.cc/terms/smcc/), [Tubulin inhibitor payloads](https://onco.cc/terms/tubulin-inhibitor-payloads/)
- trials: [A Phase III, Active-Controlled Study of SHR-A1811 Versus Trastuzumab Emtansine (T-DM1) in HER2-Positive Primary Breast Cancer Participants With Residual Invasive Disease Following Neoadjuvant Therapy](https://onco.cc/trials/nct06126640/), [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](https://onco.cc/trials/nct00781612/), [A Study Comparing BL-M07D1 With T-DM1 in Patients With Unresectable Locally Advanced or Metastatic HER2-positive Breast Cancer](https://onco.cc/trials/nct06316531/), [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](https://onco.cc/trials/nct04873362/), [A Study Evaluating the Efficacy and Safety of Biomarker-Driven Therapies in Patients With Persistent or Recurrent Rare Epithelial Ovarian Tumors](https://onco.cc/trials/nct04931342/), [A Study of BL-M07D1 Versus T-DM1 in the Adjuvant Treatment of HER2-positive Breast Cancer With Residual Invasive Cancer After Neoadjuvant Therapy](https://onco.cc/trials/nct06830889/), [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](https://onco.cc/trials/nct05081609/), [ATEMPT](https://onco.cc/trials/atempt/), [Beamion BCGC-1: A Study to Find a Suitable Dose of Zongertinib Used Alone and in Combination With Other Treatments to Test Whether it Helps People Wit](https://onco.cc/trials/nct06324357/), [CUPISCO](https://onco.cc/trials/cupisco/), [DESTINY-Breast03](https://onco.cc/trials/destiny-breast03/), [DESTINY-Breast05](https://onco.cc/trials/destiny-breast05/), [DP303c Versus Trastuzumab Emtansine in in Patients With HER2-positive Advanced Breast Cancer](https://onco.cc/trials/nct06313086/), [GATSBY](https://onco.cc/trials/gatsby/), [HER2CLIMB-02](https://onco.cc/trials/her2climb-02/), [HERACLES](https://onco.cc/trials/heracles/), [I-SPY 2](https://onco.cc/trials/i-spy-2/), [KATHERINE](https://onco.cc/trials/katherine/), [KRISTINE](https://onco.cc/trials/kristine/), [NCI-MATCH (EAY131)](https://onco.cc/trials/nci-match/), [Protein-Matched ADC or PDC Umbrella Trial in Advanced Pancreatic and Breast Cancer](https://onco.cc/trials/nct07825753/), [Tumor-agnostic Precision Immuno-oncology and Somatic Targeting Rational for You (TAPISTRY) Platform Study](https://onco.cc/trials/nct04589845/)
- ideas: [Sequencing HER2 ADCs by payload after T-DXd](https://onco.cc/ideas/idea-her2-adc-sequencing-payload/)
- roadmaps: [ADC roadmap: from Mylotarg to bispecific and dual-payload ADCs](https://onco.cc/roadmaps/adc-generations/)
- people: [Charles E. Geyer Jr.](https://onco.cc/people/charles-geyer/), [Eleftherios P. Mamounas](https://onco.cc/people/eleftherios-mamounas/), [Gunter von Minckwitz](https://onco.cc/people/gunter-von-minckwitz/), [Ian E. Krop](https://onco.cc/people/ian-krop/), [Javier Cortés](https://onco.cc/people/javier-cortes/), [Sara A. Hurvitz](https://onco.cc/people/sara-hurvitz/), [Sung-Bae Kim](https://onco.cc/people/kim-sung-bae/)
- key papers: [DESTINY-Breast03: trastuzumab deruxtecan beats T-DM1 as second-line treatment of HER2-positive metastatic breast cancer](https://onco.cc/key-papers/paper-destiny-breast03-nejm-2022/), [KATHERINE: switching to T-DM1 when HER2-positive breast cancer survives pre-surgery treatment](https://onco.cc/key-papers/paper-katherine-nejm-2019/)
- institutions: [Duke Cancer Institute](https://onco.cc/institutions/duke-cancer-institute/)
- pathways: [Breast cancer (KEGG map)](https://onco.cc/pathways/breast-cancer-signalling/), [Mitosis & the spindle assembly checkpoint](https://onco.cc/pathways/mitotic-spindle-checkpoint/)

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