Breast cancer (invasive) · T-DXd monotherapy (HER2+ metastatic 2L+, also HER2-low metastatic)

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

Knowledge-base record for audit. Provisional clinical content: this is not a prescription. An oncologist must verify original sources, applicability and review status. Full rules and constraints are in the YAML.

Source YAML: complete record

Track	standard
Linked regimen	`REG-TDXD-METASTATIC`

ID	`IND-BREAST-HER2-POS-MET-2L-TDXD`
Type	Indication
Status	reviewed 2026-04-27 \| pending_clinical_signoff
Diseases	`DIS-BREAST`
Sources	`SRC-DESTINY-BREAST03-CORTES-2022` `SRC-ESMO-BREAST-METASTATIC-2024` `SRC-HER2CLIMB-MURTHY-2019` `SRC-NCCN-BREAST-2025`

Notes

ESCAT IA. T-DXd preferred 2L per DESTINY-Breast03 (median PFS 28.8 vs 6.8 mo vs T-DM1, HR 0.33). ILD risk (~10.5% any grade) requires baseline CT chest + active monitoring; immediate hold + corticosteroids if pneumonitis suspect. UA-availability is major access barrier (registered, reimbursement under negotiation). Routed to via ALGO-BREAST-HER2-POS-2L unless brain metastases present (then HER2CLIMB tucatinib triplet preferred).

Used By

Algorithms

ALGO-BREAST-1L - ALGO-BREAST-1L
ALGO-BREAST-HER2-POS-2L - ALGO-BREAST-HER2-POS-2L

Handbook Chapters

HB-BREAST-HER2-POS-MET-1L - HER2+ metastatic breast cancer: first-line reasoning

Handbook Questions

HQ-BREAST-HER2-POS-1L-002 - HQ-BREAST-HER2-POS-1L-002