West Cancer Center

BREAST: METASTATIC: ER+: HER2-low or ultralow: POST Endocrine therapy: HERTHENA-Breast02

A Phase 1b/2, Multicenter, Open-label, Dose Regimen Determination and Dose Expansion Trial to Evaluate the Safety, Tolerability, Anti-tumor Activity, and an Optimal Dose Regimen of Patritumab Deruxtecan (HER3-DXd) With Trastuzumab Deruxtecan (T-DXd) in Participants With Hormone Receptor Positive, HER2-low or HER2-ultralow, Unresectable or Metastatic Breast Cancer (HERTHENA-Breast02)

Title

Daiichi U31402-287 Breast HER2low

Study Title

Site Link

NCT07701941

Malignancy

Breast cancer, IBC

Stage

Stage 4

Disease Setting

Metastatic/Palliative

Line Of Therapy

Post endocrine therapy, before systemic therapy

Investigational Agent

Patritumab deruxtecan

Drug Class

anti-HER3 ADC

Greg Vidal, MD, PhD

Sponsor

Daiichi Sankyo

Phase

Phase 2

Status

Open to Enrollment

Key Eligibility Criteria

Key Eligibility Criteria Details

Unresectable or metastatic pathologically documented breast cancer
HER+ based on local testing
HER2-low (IHC 2+ ISH negative, or IHC 1+) or HER2-ultralow (any membrane staining) from sample in metastatic setting
DOcumented disease progression during or after most recent treatment
Must have had CDK4/6 inhibitor
Refractory to endocrine therapy
Patients with PIK3CA mutations, AKT, or BRCA mutations must have received appropriate therapy for those alterations
No prior chemotherapy for metastatic disease
Measurable disease
No active CNS mets
ECOG PS 0-1

Objective

Primary
- ORR
Secondary
- DCR
- DOR
- PFS
- TTR
- OS
- PK
- Safety

Assessment Frequency

Assessment Frequency 2

Assessment Frequency Link

Path

ER+, HER2 low or HER2 ultralow

Dosing Frequency

Control Agents

Study Protocol

Randomized