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Study of Patritumab Deruxtecan Plus Pembrolizumab With Other Anticancer Agents in Participants With High-Risk Early-Stage Triple-Negative or Hormone Receptor-Low Positive/HER-2 Negative Breast Cancer (MK-1022-010, HERTHENA-Breast-03)

  • PhasePhase 2
  • StatusRecruiting
  • Planned enrollment372 people
  • Recruiting US sites8
  • SponsorMerck Sharp & Dohme LLC
  • RegistryNCT06797635

Recruitment re-checked on ClinicalTrials.gov Oct 30, 2026. Public record; not medical advice.

Study of Patritumab Deruxtecan Plus Pembrolizumab With Other Anticancer Agents in Participants With High-Risk Early-Stage Triple-Negative or Hormone Receptor-Low Positive/HER-2 Negative Breast Cancer (MK-1022-010, HERTHENA-Breast-03): a one-minute explainerNCT067976351 min

Eligibility

Who can join

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

  • Age18 Years to no maximum
  • SexAll
  • Healthy volunteersNo

You may be able to join if

  • The main inclusion criteria include but are not limited to the following:
  • 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

You cannot join if

  • The main exclusion criteria include but are not limited to the following:
  • Has uncontrolled or significant cardiovascular disease before randomization
  • 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 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 metastatic (Stage IV) breast cancer or cN3 nodal involvement
  • Has known additional malignancy that is progressing or has required active treatment within the past 5 years
  • Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis
  • 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 concurrent active HBV and HCV infection
  • Has clinically severe respiratory compromise resulting from intercurrent pulmonary illness

The treatment

How it is intended to work

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

patritumab deruxtecan. An antibody-drug conjugate (ADC) composed of patritumab, a monoclonal antibody directed against the human epidermal growth factor receptor HER3 (ErbB3),linked to the topoisomerase I inhibitor DX 8951, a semisynthetic, water-soluble derivative of camptothecin, with potential antineoplastic activity. Upon administration of patritumab deruxtecan, the patritumab moiety targets and binds to HER3. After internalization, DX 8951 inhibits topoisomerase I activity by stabilizing the complex between topoisomerase I and DNA and inhibiting religation of DNA breaks, thereby inhibiting DNA replication and triggering apoptotic cell death. HER3, a member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases, is frequently overexpressed in tumors. NCI Drug Dictionary

Treatments listed in the registry

  • Patritumab deruxtecan (Biological): Administered via IV infusion as neoadjuvant treatment
  • Pembrolizumab (Biological): Administered via IV infusion as neoadjuvant treatment in Part 1 and via IV infusion as neoadjuvant and adjuvant treatment in Part 2
  • Paclitaxel (Drug): Administered via IV infusion as neoadjuvant treatment
  • Carboplatin (Drug): Administered via IV infusion as neoadjuvant treatment
  • Doxorubicin hydrochloride (Drug): Administered via IV infusion as neoadjuvant treatment in Arm C and an option for adjuvant treatment for participants with residual disease in Arms A and B in Part 2
  • Epirubicin hydrochloride (Drug): Administered via IV infusion as neoadjuvant treatment in Arm C and an option for adjuvant treatment for participants with residual disease in Arms A and B in Part 2
  • Cyclophosphamide (Drug): Administered via IV infusion as neoadjuvant treatment in Arm C and an option for adjuvant treatment for participants with residual disease in Arms A and B in Part 2
  • Capecitabine (Drug): Administered via oral tablets as an option for adjuvant treatment for participants with residual disease in Part 2
  • Olaparib (Drug): Administered via oral tablets as an option for adjuvant treatment for participants with germline BRCA mutations and residual disease in Part 2

The study

Treatment groups

Randomized · Parallel · masking: None

Part 1, A: Pembrolizimab + patritumab deruxtecan → Pembrolizumab + paclitaxel + carboplatin (Experimental)

In Part 1, participants receive neoadjuvant pembrolizumab 200 mg via intravenous (IV) infusion every 3 weeks (Q3W) plus patritumab deruxtecan via IV infusion Q3W for 12 weeks, followed by pembrolizumab 200 mg via IV infusion Q3W plus paclitaxel 80 mg/m^2 via IV infusion every week (QW) and carboplatin AUC1.5 mg/ml/min via IV infusion QW for 12 weeks. At 3 to 6 weeks after last dose of neoadjuvant treatment, participants will undergo surgery for their breast cancer.

Part 2, A: Pembrolizimab + patritumab deruxtecan → Pembrolizumab + paclitaxel + carboplatin (Experimental)

In Part 2, participants receive neoadjuvant pembrolizumab 200 mg IV infusion every Q3W plus patritumab deruxtecan (dose to be determined in part 1) IV infusion Q3W for 12 weeks, followed by pembrolizumab 200 mg IV infusion Q3W plus paclitaxel 80 mg/m^2 IV infusion QW and carboplatin AUC1.5 mg/ml/min IV infusion QW for 12 weeks. At 3-6 weeks after last dose of neoadjuvant treatment, participants undergo surgery for breast cancer. After surgery, participants receive adjuvant pembrolizumab 400 mg IV every 6 weeks (Q6W) for ~30 weeks. Additional adjuvant treatment of physician's choice (TPC) may be given to participants with residual disease. TPC options are olaparib 300 mg oral twice daily (BID) for 1 year (participants with germline BRCA mutation [gBRCAm] only), capecitabine 1000-1250 mg/m^2 oral BID days 1-14 and 22-35 Q6W for 4 six-week cycles or doxorubicin 60mg/m^2 (or epirubicin 90 mg/m^2) IV Q3W or every 2 weeks (Q2W) and cyclophosphamide 600 mg/m^2 IV Q3W or Q2W for 4 doses.

Part 2, B: Pembrolizumab + paclitaxel + carboplatin → Pembrolizumab + patritumab deruxtecan (Experimental)

In Part 2, participants receive neoadjuvant pembrolizumab 200 mg IV infusion Q3W plus paclitaxel 80 mg/m^2 IV infusion QW and carboplatin AUC1.5 mg/ml/min IV infusion QW for 12 weeks, followed by pembrolizumab 200 mg IV infusion Q3W plus patritumab deruxtecan (dose to be determined in part 1) via IV infusion Q3W for 12 weeks. At 3 to 6 weeks after last dose of neoadjuvant treatment, participants will undergo surgery for their breast cancer. After surgery, participants will receive adjuvant pembrolizumab 400 mg IV infusion Q6W for ~30 weeks. Additional adjuvant TPC may be administered to participants with residual disease. TPC options include olaparib 300 mg oral BID for 1 year (participants with gBRCAm only), capecitabine 1000-1250 mg/m^2 oral BID days 1-14 and 22-35 Q6W for 4 six-week cycles or doxorubicin 60mg/m^2 (or epirubicin 90 mg/m^2) IV infusion Q3W or Q2W and cyclophosphamide 600 mg/m^2 IV infusion Q3W or Q2W for 4 doses.

Part 2, C: Pembro + paclitaxel + carboplatin→ Pembro + doxorubicin (or epirubicin) +cyclophosphamide (Active Comparator)

In Part 2, participants receive neoadjuvant pembrolizumab 200 mg IV infusion Q3W plus paclitaxel 80 mg/m^2 IV infusion QW and carboplatin AUC1.5 mg/ml/min via IV infusion QW for 12 weeks, followed by pembrolizumab 200 mg IV infusion Q3W plus doxorubicin 60mg/m^2 (or epirubicin 90 mg/m^2) IV infusion Q3W and cyclophosphamide 600 mg/m^2 IV infusion Q3W for 12 weeks. At 3 to 6 weeks after last dose of neoadjuvant treatment, participants will undergo surgery for their breast cancer. After surgery, participants will receive adjuvant pembrolizumab 400 mg IV infusion Q6W for approximately 30 weeks. Additional adjuvant TPC may be administered to participants with residual disease. TPC options include olaparib 300 mg oral BID for 1 year (participants with gBRCAm only) or capecitabine 1000-1250 mg/m^2 oral BID days 1-14 and 22-35 Q6W for 4 six-week cycles.

What it involves

Procedures

As the registry describes them. Requirements to join, such as a tissue sample, are in the eligibility list above even when on-study procedures are optional. Ask the study team which steps apply to you.

  • surgery: Part of the study plan

Goals

What the study measures

Main goals

  • Part 1: Number of Participants Experiencing an Adverse Event (AE) (Up to ~43 weeks)
  • Part 1: Number of Participants Who Experience One or More Dose-Limiting Toxicities (DLTs) (Up to 21 days)
  • Part 1: Number of Participants who Discontinued Study Treatment Due to an AE (Up to ~30 weeks)
  • Part 2: Pathological Complete Response (pCR) Rate Using the Definition of ypT0/Tis ypN0 (Up to ~30 weeks)
  • Part 2: Number of Participants Experiencing an AE (Up to ~103 weeks)
  • Part 2: Number of Participants who Discontinued Study Treatment Due to an AE (Up to ~90 weeks)

Other goals

  • Part 2: pCR-No Ductal Carcinoma in Situ (DCIS) Rate Using the Definition of ypT0 ypN0
  • Part 2: Event-Free Survival (EFS)
  • Part 2: Overall Survival (OS)
  • Part 2: Distant Progression or Distant Recurrence-Free Survival (DPDRFS)
  • Part 2: Residual Cancer Burden (RCB)

Planned enrollment: 372 (estimated).

Where

Recruiting US sites

  • UCLA Hematology/Oncology - Parkside ( Site 0021), Santa Monica, California
  • Orchard Healthcare Research Inc. ( Site 0006), Skokie, Illinois
  • Intermountain Health St. Vincent Regional Hospital - Cancer Centers of Montana ( Site 0003), Billings, Montana
  • Northwest Cancer Specialists (Compass Oncology) ( Site 8003), Tigard, Oregon
  • SCRI Oncology Partners ( Site 7000), Nashville, Tennessee
  • Texas Oncology - DFW ( Site 8000), Dallas, Texas
  • Houston Methodist Hospital ( Site 0022), Houston, Texas
  • Virginia Oncology Associates (VOA) ( Site 8001), Norfolk, Virginia

9 recruiting sites outside the US. Site status as of Oct 30, 2026. Check the live record before contacting a site.

Sources

Where this comes from

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Sep 9, 2026. Public record; not medical advice.

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