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Taking people in SpainPhase 2

Tests patritumab deruxtecan with pembrolizumab in early breast cancer

Tests patritumab deruxtecan and pembrolizumab with chemotherapy in adults with early triple-negative breast cancer.

Key facts

Who runs it
Merck Sharp & Dohme LLC
Where
Badalona, Barcelona, Córdoba, Madrid, Málaga, and Valencia, SpainSee the 7 sites
Trial code
Registry title
A clinical study of patritumab deruxtecan in people with breast cancer
Status
Recruiting
Phase
Phase 2
People taking part
10 people, planned
Started
15 Oct 2025
Expected to end
20 Dec 2034
Type of study
Interventional
Record updated
8 October 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults with newly diagnosed, high-risk early-stage triple-negative or hormone receptor-low positive/HER2-negative breast cancer that has not spread to distant parts of the body and has not yet been treated.

Age
18 years or older
Sex
All sexes
Disease stage
Locally advanced breast cancer that has not spread to other organs (M0), with tumor and lymph node stage cT1c N1-N2, cT2 N0-N2, cT3 N0-N2 or cT4a-d N0-N2. The cancer must be triple-negative or HR-low+/HER2- and confirmed centrally.
Earlier treatment
No earlier treatment for this breast cancer, including radiation, drug therapy or definitive surgery. No earlier treatment with anti-PD-1, anti-PD-L1 or anti-PD-L2 drugs. No earlier treatment with an anti-HER3 antibody or an antibody-drug conjugate with an exatecan derivative, such as trastuzumab deruxtecan.
Biomarker or test result
Triple-negative or HR-low+/HER2- breast cancer, confirmed centrally. Left ventricular ejection fraction of 50% or more, or at least the lower limit of normal.

Main reasons for not taking part

  • Breast cancer that has spread to other organs (Stage IV) or cN3 lymph node involvement
  • Active spread to the brain or spinal fluid, or leptomeningeal carcinomatosis
  • Any history of interstitial lung disease or pneumonitis, or current or suspected interstitial lung disease
  • Uncontrolled or significant heart disease, or clinically significant corneal disease
  • Active infection needing systemic therapy, or active hepatitis B and hepatitis C infection together

The registry criteria, word for word

Show all 21 criteriaShow less

Who can take part

  • Has locally advanced, non-metastatic (M0), breast cancer, defined as any of the following combined primary tumor (T) and regional lymph node (N) staging per current American Joint Committee on Cancer (AJCC) criteria: cT1c, N1-N2; cT2, N0-N2; cT3, N0-N2; or cT4a-d, N0-N2
  • Has centrally confirmed diagnosis of breast cancer that is triple-negative or HR-low+/HER2- breast cancer that will be treated according to the triple-negative breast cancer (TNBC) paradigm
  • Participants who are Hepatitis B surface antigen (HBsAg) positive are eligible if they have received Hepatitis B virus (HBV) antiviral therapy for at least 4 weeks and have undetectable HBV viral load
  • Participants with a history of Hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable
  • Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 within 28 days prior to allocation/randomization
  • Has left ventricular ejection fraction (LVEF) of ≥50% or ≥ lower limit of normal (LLN) as assessed by echocardiogram (ECHO) or multigate acquisition scan (MUGA) scan

Who cannot take part

  • Has concurrent active HBV and HCV infection
  • Has received prior therapy with an anti-programmed death (PD)-1, anti-PD-L1, or anti-PD-L2 agent, or with an agent directed to another stimulatory or coinhibitory T-cell receptor
  • Has received any prior treatment, including radiation, systemic therapy, and/or definitive surgery for currently diagnosed breast cancer
  • Has received prior treatment with an anti-human epidermal growth factor receptor 3 (HER3) antibody and/or antibody-drug conjugate (ADC) that consists of an exatecan derivative that is a topoisomerase I inhibitor (e.g., trastuzumab deruxtecan)
  • Has uncontrolled or significant cardiovascular disease before randomization
  • Has known additional malignancy that is progressing or has required active treatment within the past 5 years
  • Has any history of interstitial lung disease (ILD)/pneumonitis irrespective of steroid use, or current or suspected ILD
  • Has an active infection requiring systemic therapy
  • Has clinically severe respiratory compromise resulting from intercurrent pulmonary illness
  • Has any history of or evidence of any current leptomeningeal carcinomatosis
  • Has clinically significant corneal disease
  • Has human immunodeficiency virus (HIV) infection with a history of Kaposi sarcoma and/or multicentric Castleman disease
  • Has evidence of ongoing, uncontrolled, systemic bacterial, fungal, or viral infection
  • Has metastatic (Stage IV) breast cancer or cN3 nodal involvement
  • Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis

Where in Spain

  • Institut Catala d'OncologiaBadalona, SpainTaking people
  • Hospital Universitari Vall d'HebronBarcelona, SpainTaking people
  • Hospital Universitario Reina SofiaCórdoba, SpainTaking people
  • Clinica Universidad de NavarraMadrid, SpainTaking people
  • Hospital Universitario 12 de OctubreMadrid, SpainTaking people
  • Hospital Universitario Virgen de la VictoriaMálaga, SpainTaking people
  • Fundación Instituto Valenciano de OncologíaValencia, SpainTaking people

About the trial

What the trial wants to find out

1. Part 1 Objective: To evaluate safety and tolerability of neoadjuvant patritumab deruxtecan (HER3-DXd) plus pembrolizumab before carboplatin/ paclitaxel plus pembrolizumab. 2. Part 2 Objective: To compare HER3-DXd plus pembrolizumab before carboplatin/paclitaxel plus pembrolizumab versus carboplatin/paclitaxel plus pembrolizumab followed by AC/EC plus pembrolizumab with respect to rate of pCR (ypT0/Tis ypN0) at the time of definitive surgery, as assessed by local pathologist. 3. Part 2 Objective: To compare HER3-DXd plus pembrolizumab after carboplatin/paclitaxel plus pembrolizumab versus carboplatin/paclitaxel plus pembrolizumab followed by AC/EC plus pembrolizumab with respect to rate of pCR (ypT0/Tis ypN0) at the time of definitive surgery, as assessed by local pathologist. 4. Part 2: To evaluate safety and tolerability of study interventions in all arms.

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record

Print a page for my doctor

Data and sources

Registry record
Listed on the EU's official list of trials (CTIS).
Official title
An Open-label Randomized Phase 2 Study to Evaluate Safety and Efficacy of Patritumab Deruxtecan Plus Pembrolizumab Administered Either Before or After Carboplatin/Paclitaxel Plus Pembrolizumab Compared With Pembrolizumab in Combination With Chemotherapy Followed by Surgery and Adjuvant Pembrolizumab for High-Risk Early-Stage Triple-Negative or Hormone Receptor-Low Positive/Human Epidermal Growth Factor Receptor-2 Negative Breast Cancer (HERTHENA-Breast03)
Plain-language title
Tests patritumab deruxtecan with pembrolizumab in early breast cancerGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 9 November 2026.
Record updated
8 October 2026