T-DXd Based Therapy Followed by Endocrine Therapy Plus Dual HER2 Blockade in First-line HER2+/ HR+ Metastatic Breast Cancer and Retreatment With T-DXd

Sponsor
Daiichi Sankyo
Study ID
NCT07683754
Phase
PHASE3
Status
Not Yet Recruiting

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Conditions

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • Trastuzumab deruxtecan — DRUG
    Upfront treatment: One IV infusion Q3W 5.4 mg/kg (starting dose) on Day 1 of each 21-day cycle T-DXd Retreatment: One IV infusion Q3W 5.4 mg/kg (starting dose) on Day 1 of each 21-day cycle \*Dose reductions implemented during Upfront treatment phase will be maintained.
  • Trastuzumab — DRUG
    Maintenance treatment: One IV infusion Q3W 6 mg/kg on Day 1 of each 21-day cycle
  • Pertuzumab — DRUG
    Upfront treatment: One IV infusion Q3W loading dose of 840 mg, then 420 mg Q3W thereafter on Day 1 of each 21-day cycle Maintenance treatment: One IV infusion Q3W 420 mg on Day 1 of each 21-day cycle
  • Endocrine Therapy — DRUG
    Aromatase inhibitors or fulvestrant administered as approved product label
  • Palbociclib — DRUG
    Maintenance treatment: Daily (3 out of 4 weeks, Q4W) oral 125 mg

Study Details

This study will evaluate a structured sequential treatment strategy starting with T-DXd + pertuzumab upfront therapy, followed by an optimized maintenance therapy with dual HER2+blockade + CDK4/6i + ET and the opportunity to retreat with T-DXd once patients progress under maintenance aimed to maximizing disease control, optimizing tolerability, and preserving T-DXd as a future therapeutic option, while ensuring participant safety and regulatory compliance in participants with HER2+/HR+ advanced/metastatic breast cancer.

Key Dates

First listed
Jul 6, 2026
Start date
Sep 4, 2026
Status verified
Jul 2026
Primary completion
Jul 4, 2030
Completion
Aug 28, 2030

Study Design

Enrollment
200 participants (estimated)
Allocation
NA
Intervention model
SEQUENTIAL
Primary purpose
TREATMENT

Arms

  • Experimental: T-DXd
    Adult participants with previously untreated advanced or metastatic HER2+/HR+ breast cancer who will receive T-DXd intravenously every 3 weeks (IV Q3W) in 3 treatment phases: Upfront treatment phase: T-DXd + pertuzumab IV Q3W Maintenance treatment phase: Trastuzumab + palbociclib + endocrine therapy + pertuzumab IV Q3W T-DXD retreatment phase: T-DXd monotherapy IV Q3W

Primary Outcome Measure

Progression-free Survival (PFS) Rate at 24 Months [ Time Frame: From start of Upfront Treatment phase until disease progression (PD) or death, whichever occurs first, up to approximately 24 months ]

Central Contacts

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