A Study of Patritumab Deruxtecan (HER3-DXd) in Combination With Trastuzumab Deruxtecan (T-DXd) in… (NCT07701941) | Clinical Trial Compass
Not Yet RecruitingPhase 1/2
A Study of Patritumab Deruxtecan (HER3-DXd) in Combination With Trastuzumab Deruxtecan (T-DXd) in Participants With HR-Positive, HER2-Low or HER2-Ultralow Unresectable or Metastatic Breast Cancer
220 participantsStarted 2026-08-03
Plain-language summary
The primary purpose of the study is to assess the safety, tolerability, and anti-tumor activity of HER3-DXd and T-DXd in the combination dosing regimens in participants with hormone receptor positive, HER2-low or HER2-ultralow, unresectable, or metastatic breast cancer.
Who can participate
Age range
18 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion criteria
. Pathologically documented breast cancer that meets the following:
. Unresectable or metastatic.
. HR+ based on testing performed locally. HR+ (estrogen receptor \[ER\] and/or progesterone receptor \[PgR\] positive \[ER or PgR greater than equal to (≥)1 percent (%)\] per American Society of Clinical Oncology \[ASCO\]/College of American Pathologists \[CAP\] 2020 guidelines) in the unresectable or metastatic setting.
. Assessed as HER2-low (defined as Immunohistochemistry (IHC)2+/In-situ hybridization (ISH)- or IHC1+) or HER2-ultralow (defined as IHC 0 with any membrane staining in greater than (\>) 0 and lesser than equal to (≤)10% of the cancer cells) locally for Part 1 and centrally for Part 2. The HER2 result must be from a tumor sample obtained in the unresectable or metastatic setting.
. Provides a pretreatment tumor tissue sample that meets one of the following collection requirements:
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Part 1: Number of Participants With at Least One Treatment-emergent Adverse Event (TEAE) and Serious Adverse Event (SAE)
Timeframe: Up to approximately 4.5 years
2
Part 2: Objective Response Per Response Evaluation Criteria in Solid Tumours Version 1.1 (RECIST v.1.1) as Assessed by the Investigator
Timeframe: Up to approximately 4.5 years
Trial details
NCT IDNCT07701941
SponsorDaiichi Sankyo
Sponsor typeINDUSTRY
Study typeINTERVENTIONAL
Primary completion2031-01-01
Contact for this trial
Daiichi Sankyo Contact for Clinical Trial Information
. Tissue biopsy collected from ≥1 lesion not previously irradiated and performed since progression with the most recent systemic cancer therapy regimen and prior to signature of the Tissue Screening informed consent form (ICF) (ARCHIVAL PRETREATMENT sample).
. Newly obtained pretreatment tumor biopsy from ≥1 lesion not previously irradiated and amenable to sampling, after signature of the Tissue Screening ICF (FRESH PRETREATMENT sample).
. Documented radiologic disease progression as per investigator assessment per RECIST v1.1 criteria (during or after most recent treatment).
Exclusion criteria
. Prior treatment with an anti-HER3 antibody and/or antibody-drug conjugate (ADC) that consists of a topoisomerase I inhibitor (e.g., T-DXd) or any other topoisomerase I inhibitor therapy.
. Has any history of interstitial lung disease (ILD)/pneumonitis irrespective of steroid use, or current ILD, or suspected ILD, or ILD that cannot be ruled out by imaging at Screening. Examples of suspected ILD/pneumonitis by imaging include the presence of lung parenchymal fibrosis, such as CPFE, and any radiographic features consistent with ILA, including but not limited to, extensive ground glass opacities, reticular opacities, traction bronchiectasis, and honeycombing. Participants may be eligible if they had history of radiation pneumonitis that did not require steroids.
. Is receiving chronic systemic corticosteroids dosed at \>10 mg prednisone daily or equivalent anti-inflammatory activity or any form of immunosuppressive therapy prior to randomization. Participants who require use of bronchodilators, inhaled or topical steroids, or local steroid injections may be included in the trial.
. Evidence of spinal cord compression or brain metastases, defined as being clinically active and symptomatic, or requiring therapy with corticosteroids or anticonvulsants to control associated symptoms. Participants with clinically inactive or treated brain metastases who are asymptomatic (i.e., without neurologic signs or symptoms and do not require treatment with corticosteroids or anticonvulsants) may be included in the trial but must have a stable neurologic status for ≥4 weeks prior to Cycle 1 Day 1. Participants with asymptomatic brain metastases and treated with anticonvulsants as prophylaxis can enroll.
. Inadequate washout period of prior treatment before randomization:
. Whole brain radiation therapy less than (\<)28 days.
. Monoclonal antibodies other than immune checkpoint inhibitors, such as anti-vascular endothelial growth factor (VEGF) (e.g., bevacizumab) and anti-epidermal growth factor receptor (EGFR) (e.g., cetuximab) \< 28 days.