Living dossier · Competitive landscape

HER2 in Breast cancer

Primary identifiers: 10
Sponsors tracked: 8
Evidence types: 2 of 3
Last refreshed: 2026-07-28 · monthly

MightyRayn panel synthesis

OmniRayn’s reading of this landscape — our interpretation, not a registry fact

The notable movement here is in the target definition itself. The registry shows the leading conjugate tested not only in HER2-positive disease but in HER2-low and even immunohistochemistry-zero populations — the antigen bar for treatment is being renegotiated downward, which widens the addressable population without a new molecule. Behind that, a crowded field of later entrants is running the same comparison against the earlier-generation conjugate. The literature supplies the constraint the trials do not: resistance at progression frequently involves loss of HER2 expression itself rather than payload failure, and a real-world series found that giving a TROP2 conjugate and this one in sequence produced short benefit on the second, because they deliver the same payload. Read against our TROP2 landscape, the two targets are not independent shots on goal — sequencing them wastes the second, while one group proposes combining them at low dose precisely to work around antigen loss.

Programs and primary evidence

Sponsor	Asset	Phase	Mechanism	Primary source
Daiichi Sankyo	T-DXd vs T-DM1 (DESTINY-Breast03)	3	anti-HER2 antibody-drug conjugate versus an earlier-generation conjugate	NCT03529110 — Phase 3 in HER2-positive metastatic breast cancer previously treated with trastuzumab and a taxane
Daiichi Sankyo	T-DXd (DESTINY-Breast15)	3	anti-HER2 ADC extended to HER2-low and IHC-zero disease	NCT05950945 — Phase 3b in unresectable or metastatic HER2-low or HER2 immunohistochemistry 0 breast cancer
AstraZeneca	T-DXd (DESTINY-Breast06)	3	anti-HER2 ADC in HER2-low, hormone-receptor-positive disease	NCT04494425 — Versus investigator's choice chemotherapy after progression on endocrine therapy
AstraZeneca	T-DXd +/- pertuzumab (DESTINY-Breast09)	3	anti-HER2 ADC moved into first line	NCT04784715 — Versus taxane, trastuzumab and pertuzumab in HER2-positive first-line metastatic disease
Sun Yat-Sen Memorial Hospital	Disitamab vedotin + pyrotinib	3	HER2 ADC combined with a HER2 tyrosine-kinase inhibitor	NCT06278870 — First-line versus taxane, trastuzumab and pertuzumab in HER2-positive advanced breast cancer
Chia Tai Tianqing	TQB2102	3	HER2 ADC versus an earlier-generation conjugate	NCT07008976 — Versus trastuzumab emtansine in HER2-positive advanced breast cancer
Sichuan Kelun-Biotech	A166	3	HER2 ADC versus an earlier-generation conjugate	NCT06968585 — Versus trastuzumab emtansine after prior trastuzumab and taxane therapy
Sichuan Baili Pharmaceutical	BL-M07D1	3	HER2 ADC versus an earlier-generation conjugate	NCT06316531 — Versus trastuzumab emtansine in unresectable locally advanced or metastatic HER2-positive disease
Memorial Sloan Kettering Cancer Center	paired pre/post-treatment specimen study	—	resistance via loss of HER2 expression and via ERBB2 binding-interface mutations	10.1158/2159-8290.CD-25-0647 — Among paired specimens, a large share showed major decreases in HER2 expression at progression, many with complete loss; authors propose combining with TROP2-directed ADCs to deliver a shared payload despite antigen loss
Oncopole Claudius Regaud	ADC-Low retrospective series	—	sequential administration of two ADCs sharing a payload	10.1038/s41416-024-02766-9 — Giving a TROP2 conjugate and a HER2 conjugate one after another in HER2-low disease produced short median progression-free survival on the second, with primary resistance in over half of patients

Method and limits

Programs are enumerated from primary registries (ClinicalTrials.gov, PubMed). A program appears here only if a primary record links this target to this indication as a therapeutic hypothesis — associations and risk markers are excluded by design.
Every claim above carries the identifier it rests on. We report what the record states; we do not assert efficacy, and computational findings are pending wet-lab confirmation.
Absence is not evidence of absence: unregistered, non-US and stealth-stage programs are not visible to these sources.
This page refreshes monthly (no net-new primary entity in 172 days). Mechanism classifications are our reading of the public record and may be revised.

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