FDA expands Enhertu use to HR-positive HER2-low and HER2-ultralow metastatic breast cancer

Evidence stage: Later-Stage HumanRegulatory status: FDA-approved for the exact stated cancer/useGuideline status: Not addressed

The U.S. FDA approved an expanded indication for trastuzumab deruxtecan (Enhertu) dated January 27, 2025, covering HR-positive, HER2-low or HER2-ultralow unresectable or metastatic breast cancer after progression on endocrine therapy — the exact scope of the approval per FDA materials; this scope must not be broadened to other breast cancer populations. Clinical evidence: the DESTINY-Breast06 trial. Primary publication: PMID 39282896, https://pubmed.ncbi.nlm.nih.gov/39282896/, DOI https://doi.org/10.1056/NEJMoa2407086. Trial registry: https://clinicaltrials.gov/study/NCT04494425. Interstitial lung disease/pneumonitis is a known safety concern associated with this drug class and should be discussed using the primary evidence/FDA materials’ own safety context, not omitted. [Identifiers as supplied by the governing task directive, attributed to independent verification outside this environment — NOT independently re-verified live here; format-validated only.]

What This Means

A specific expanded FDA approval exists for trastuzumab deruxtecan in a defined HR-positive, HER2-low/ultralow metastatic breast cancer population after endocrine therapy, based on a significant progression-free-survival benefit in DESTINY-Breast06.

What This Doesn't Mean

This is not a general HER2-low breast cancer approval, does not apply outside the stated population or treatment-line context, and — because overall-survival data were immature at this analysis — does not yet establish a confirmed survival benefit.

Why It Matters

Extends a targeted-therapy option to a population (HER2-ultralow) not previously captured by standard HER2 testing categories — a real precision-medicine/diagnostic-category expansion.

Promise & Proof

Proof — strength of the evidence 5 / 5
  • Base score from evidence stage: Later-Stage Human.
  • FDA-approved for the exact stated cancer/use.
Promise — potential significance if later evidence holds up 3 / 5
  • Baseline — a validly-evidenced story starts here; every further point below is an explicit, checkable reason.
  • The record includes substantive editorial reasoning about why this discovery matters.
  • A distinct follow-on/confirmatory study or trial is already cited as a secondary source — the field is already building on this finding.

These two ratings are automatically computed from this story's own structured evidence fields and are shown separately on purpose — they are never combined into one score. They describe this record, not a medical recommendation: they do not establish medical certainty, do not substitute for reading the cited sources, and are recalculated whenever the underlying evidence changes.

Population / Applicability

Studied in: HR-positive, HER2-low or HER2-ultralow, unresectable or metastatic breast cancer, after progression on endocrine therapy — this exact scope must not be broadened. (Unspecified)

Scope is specifically HR-positive/HER2-low-or-ultralow/post-endocrine-therapy — not a general HER2-low or general metastatic breast cancer approval. Interstitial lung disease/pneumonitis is an important, known safety issue for this drug class and must be included, not omitted or minimized. Overall-survival data were immature at this analysis and this must not be silently dropped from any PFS-benefit framing.

Full evidence details
Study design
Randomized controlled trial
Sample size
866

Funding & Conflicts

Primary trial funding: AstraZeneca and Daiichi Sankyo (as reported via the source-verification pass; original disclosure statement itself not independently re-read — confirm exact wording against the publication during human review).

Regulatory status by jurisdiction

United States (FDA)

Status
FDA-approved for the exact stated cancer/use
Indication
HR-positive, HER2-low or HER2-ultralow unresectable/metastatic breast cancer that progressed on one or more endocrine therapies in the metastatic setting.
Biomarker requirement
HER2-low or HER2-ultralow
Decision date
2025-01-27
Source
Regulator record (opens in a new tab)

Guideline positions

Guideline

Position
Not addressed
Last verified
2026-08-11

Primary evidence supporting this story

Additional context

Why Should I Trust This?

  • Last reviewed: 2026-08-11

This panel summarizes real, checkable facts about this record's own sources and review status — it is not a trust score, and reading it is not a substitute for reading the cited sources yourself.

Discovery Timeline

Every recorded change to this record's content or publication status, in order.

  1. Status change — Status changed from "In editorial review" to "Verified".

Last reviewed

Related discoveries

FDA expands Enhertu use to HR-positive HER2-low and HER2-ultralow metastatic breast cancer

https://cancerdiscoveries.com/discoveries/fda-expands-enhertu-use-to-hr-positive-her2-low-and-her2-ultralow-metastatic-breast-cancer/

Evidence stage: Later-Stage Human

What This Means

A specific expanded FDA approval exists for trastuzumab deruxtecan in a defined HR-positive, HER2-low/ultralow metastatic breast cancer population after endocrine therapy, based on a significant progression-free-survival benefit in DESTINY-Breast06.

What This Doesn't Mean

This is not a general HER2-low breast cancer approval, does not apply outside the stated population or treatment-line context, and — because overall-survival data were immature at this analysis — does not yet establish a confirmed survival benefit.

Why It Matters

Extends a targeted-therapy option to a population (HER2-ultralow) not previously captured by standard HER2 testing categories — a real precision-medicine/diagnostic-category expansion.

Primary sources

  • FDA-approved indication expansion; DESTINY-Breast06 (NEJM) — https://doi.org/10.1056/NEJMoa2407086 (DOI 10.1056/NEJMoa2407086, PMID 39282896)

Date verified: 2026-08-11

Correction status: No correction or retraction