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Metastatic Breast Cancer ( HER2 Negative)Phase 2H3RAKLESNCT07193394

Tucatinib and Trastuzumab in HER3-mutant and HER2-not Amplified Metastatic Breast Cancer

A Phase 2 study testing Tucatinib (ONT-380) and Trastuzumab (Herceptin) in people with Metastatic Breast Cancer ( HER2 Negative) and Unresectable Breast Cancer, run by Institut Curie at 9 sites in France.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

The H3RAKLES trial would allow patients with a progressive metastatic breast cancer to have access to one more line of systemic therapy. Patients included in this trial will have already received at least two lines of chemotherapy (and potentially several lines of endocrine therapy for patients with a HR+ disease). Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Tucatinib (ONT-380) and Trastuzumab (Herceptin)
Could I receive a placebo?
No, everyone receives an active treatment
How many people
20 participants
Where
9 sitesFrance
Study dates
31 Jan 2026to 8 Jun 2029
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Age ≥ 18 years
  • Metastatic or unresectable breast cancer
  • HER2-negative (defined as having an IHC 0+, IHC 1+, or IHC 2+ and ISH non-amplified, per ASCO/CAP guidelines) on last assessable tumor sample
  • Having received ≥ 2 previous chemotherapy lines for advanced breast cancer: including at least one line of conjugated antibody, at the investigator's discretion or if a germinal BRCA mutation is present, a PARP inhibitor.
  • Class IV or V somatic ERBB3 mutation as determined on a tumor sample obtained during the molecular screening step
  • ECOG performance status ≤ 2 (Appendix A)
Show all 17Show fewer
  • Evaluable disease, per RECIST v1.1 inclusion criteria
  • Left ventricular ejection fraction (LVEF) ≥50% as assessed by echocardiogram (ECHO) or multiple-gated acquisition scan (MUGA) documented within 4 weeks prior to first dose of study treatment
  • Adequate organ function:
  • Creatinine clearance ≥ 50 mL/min as calculated per institutional guidelines
  • Total bilirubin ≤1.5 X upper limit of normal (ULN), except for patients with known Gilbert's disease, who may enroll if the conjugated bilirubin is ≤1.5 X ULN.
  • Transaminases (aspartate aminotransferase and alanine aminotransferase) ≤ 2.5 X ULN (≤ 5 X ULN if the patient has liver metastases)
  • Women of childbearing potential (WCBP) must have a negative serum pregnancy test < 7 days prior to first dose of treatment. A woman is considered of childbearing potential following menarche and until becoming post-menopausal unless permanently sterile. A postmenopausal state is defined as the absence of menses for 12 months without an alternative cause.
  • WCBP (as defined above) and men with partners of childbearing potential must agree to use a highly effective birth control method during the study and for 3 months after completion of investigational treatment.
  • Patients should be eligible for the treatment step according to the investigator's opinion.
  • Patients must be covered by a health insurance plan.
  • Patients able to provide signed informed consent.

Who cannot join

  • Having received any prior treatment targeting HER2. Prior treatment with trastuzumab deruxtecan is allowed, per label, in patients with HER2-low metastatic breast cancer (IHC 1+ or 2+, ISH non-amplified)
  • History of allergic reactions to trastuzumab or tucatinib or chemically similar drugs
  • Patients who are pregnant, breastfeeding, or planning a pregnancy from time of informed consent until 7 months after the final dose of study drug
  • Inability to swallow pills or having a significant gastro-intestinal disease or a history of surgery which would preclude the adequate oral absorption of medications
  • Having used a strong CYP2C8 inhibitor within a duration of 5 half-lives prior to the first dose of study treatment, or have used a strong CYP3A4 or CYP2C8 inducer within 5 days prior to first dose of study treatment (see Appendix B and Appendix C)
  • Treatment with any systemic anti-cancer therapy (including hormonal therapy), non-central nervous system (CNS) radiation, or experimental agent ≤ 3 weeks prior to the first dose of study treatment, except gonadotropin releasing hormone (GnRH) agonists
Show all 30Show fewer
  • Participation in another interventional clinical trial.
  • Symptomatic and untreated brain metastases or brain metastases requiring urgent treatment, or brain metastases requiring a dose > 2 mg of dexamethasone (or equivalent)
  • Whole brain radiotherapy < 21 days prior to first dose of treatment, stereotactic radiotherapy < 7 days prior to first dose of treatment
  • Leptomeningeal metastases
  • Major surgery (including surgery of brain metastases) < 21 days prior to first dose of treatment
  • Evidence within 2 years of the start of study treatment of another malignancy that required systemic treatment
  • Have known myocardial infarction or unstable angina within 24 weeks prior to first dose of study treatment
  • Have clinically significant cardiopulmonary disease such as:
  • Ventricular arrhythmia requiring therapy,
  • Uncontrolled hypertension (defined as persistent systolic blood pressure >150 mmHg and/or diastolic blood pressure > 100 mm Hg on antihypertensive medications)
  • Any history of symptomatic congestive heart failure
  • Severe dyspnea at rest (CTCAE v5.0 Grade 3 or above) due to complications of advanced malignancy
  • Hypoxia requiring supplementary oxygen therapy except when oxygen therapy is needed only for obstructive sleep apnea
  • Presence of ≥ Grade 2 QTc prolongation on screening ECG
  • Conditions potentially resulting in drug-induced prolongation of the QT interval or torsade de pointes:
  • Congenital or acquired long QT syndrome
  • Family history of sudden death
  • History of previous drug-induced QT prolongation
  • Current use of medications with known and accepted associated risk of QT prolongation (see row "Accepted Association" in Appendix D)
  • Are known carriers of active Hepatitis B or Hepatitis C or have other known chronic liver disease
  • Are known to be positive for human immunodeficiency virus (HIV)
  • Altered mental status or psychiatric disorder that, in the opinion of the investigator, would preclude a valid patient informed consent.
  • Patients who have difficulty undergoing trial procedures for geographic, social or psychological reasons
  • Person deprived of liberty or under guardianship

Trial locations and contacts

9 sites in 1 country. Contact the study team or a site near you to ask about taking part.

Sandra Clinical Project Manager contact

+33156245944

drci.promotion@curie.fr

Sandra Regulatory Assistant contact

+33156245765

drci.promotion@curie.fr

9 sites in 1 country

France9 sites, 9 recruiting
  • Polyclinique Bordeaux Nord Aquitaine

    Bordeaux, 33 300

    Laura POETSCH, MD

    Laura POETSCH, MD

    Not yet recruiting
  • Chu Dupuytren- Limoges

    Limoges, 87 042

    Elise DELUCHE, MD

    Elise DELUCHE, MD

    Not yet recruiting
  • Institut Paoli-Calmettes

    Marseille, 13009

    Alexandre TASSIN DE NONNEVILLE, MD

    Alexandre TASSIN DE NONNEVILLE, MD

    Not yet recruiting
  • Centre Antoine Lacassagne

    Nice, 06 189

    Marc PUJALTE-MARTIN, MD

    Marc PUJALTE-MARTIN, MD

    Not yet recruiting
  • CHU de Nîmes

    Nîmes, 30 029

    Frédéric FITENI, MD

    Frédéric FITENI, MD

    Not yet recruiting
  • Centre Eugène Marquis

    Rennes, 35 042

    Antoine DELEUZE, MD

    Antoine DELEUZE, MD

    Not yet recruiting
  • Institut Curie_ Site Saint-Cloud

    Saint-Cloud, 92 210

    Nicolas KIAVUE, MD

    Nicolas KIAVUE, MD

    Recruiting
  • Institut Universitaire du Cancer de Toulouse (IUCT) - Oncopole Claudius Regaud

    Toulouse, 31 059

    Florence DALENC, MD

    Florence DALENC, MD

    Not yet recruiting
  • Institut de Cancérologie de Lorraine

    Vandœuvre-lès-Nancy, 54 519

    Vincent MASSARD, MD

    Vincent MASSARD, MD

    Not yet recruiting

Other trials in France

About this study

Official title: Tucatinib and Trastuzumab in HER3-mutant and HER2-not Amplified Metastatic Breast Cancer: a Proof of Concept Study (H3RAKLES)

The H3RAKLES trial would allow patients with a progressive metastatic breast cancer to have access to one more line of systemic therapy. Patients included in this trial will have already received at least two lines of chemotherapy (and potentially several lines of endocrine therapy for patients with a HR+ disease). In this setting, few treatments have demonstrated a clinically meaningful benefit, and any additional option is valuable. Furthermore, the pre-clinical and clinical rationale indicate a high probability of clinical benefit, as previously shown in Table 1, with all patients treated with trastuzumab and a TKI targeting HER2 displaying a response. Besides, with several years of hindsight for the combination of lapatinib, trastuzumab and capecitabine, we expect excellent tolerance with the same treatment without capecitabine.

The H3RAKLES single-arm phase II trial will evaluate the combination of tucatinib, a HER2 TKI, and trastuzumab, a HER2-directed antibody in patients with a HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation. To demonstrate the actionability of ERBB3 mutations, all patients will receive a combination of trastuzumab and tucatinib, in 3-weeks cycles.

Read the detailed description

For breast cancers in which HER2 is not overexpressed, activating mutations in the ERBB3 gene, coding for the HER3 tyrosine kinase receptor, have an oncogenic role, and targeting them may offer new perspectives of treatment.

Pre-clinical data suggest that HER2 is essential for the pro-tumoral effect of HER3, which does not have a functional tyrosine kinase domain and requires heterodimerization with other members of the HER family of tyrosine kinase receptors for signaling. There is limited clinical evidence of the activity of drugs targeting HER2 in cancers harboring ERBB3 mutations, but few patients with breast cancer have been evaluated. Furthermore, the distribution of ERBB3 mutations seems to differ in breast carcinoma when compared to other cancer types. A few patients with a HER2 non-amplified metastatic breast cancer were treated at Institut Curie with the combination of a HER2-directed antibody and of a HER2 tyrosine kinase inhibitor (TKI) and all responded, warranting further explorations in this setting.

The H3RAKLES single-arm phase II trial will evaluate the combination of tucatinib, a HER2 TKI, and trastuzumab, a HER2-directed antibody, with a Bayesian design in patients with a HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation.

To demonstrate the actionability of ERBB3 mutations, all patients will receive a combination of trastuzumab and tucatinib, in 3-weeks cycles, until cancer progression, inacceptable toxicity or patient's withdrawal from the trial.

Tumor radiological assessments will be performed every 6 weeks during the 6 first months (first 8 cycles), then every 9 weeks until disease progression. In addition, Quality of Life will be evaluated throughout the treatment.

Blood samples (at baseline, cycles 1, 2 and 3, and at end of treatment) and tissue samples (at baseline and optionally at progression) will be collected as part as exploratory objective analyses on biomarkers (ctDNA monitoring and next-generation sequencing (NGS)).

Being tested
Tucatinib (ONT-380), Trastuzumab (Herceptin)
Keywords
Breast, Cancer, HER2, tucatinib, trastuzumab, HER3, metastatic, unresectable
Medical subject headings
Breast Neoplasms, Neoplasms, Neoplasm Metastasis

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Tucatinib (ONT-380)Drug

    Patients with a HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation will receive experimental treatment with tucatinib and trastuzumab combination

  • Trastuzumab (Herceptin)Drug

    Patients with a HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation will receive experimental treatment with tucatinib and trastuzumab combination

Study groups in NCT07193394
Study groupRoleWhat they receive
Treatment with tucatinib and trastuzumab combinationExperimentalPatients with HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation, treated with a combination of tucatinib and trastuzumab
Receives: Drug: Tucatinib (ONT-380); Drug: Trastuzumab (Herceptin)

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Clinical benefit rate (CBR)

    Clinical benefit rate (CBR), defined as the proportion of patients who achieved a complete response (CR), a partial response (PR), or had stable disease (SD) for 24 weeks or more, according to the investigator-assessed RECIST v1.1 criteria.

    Measured: 24 weeks

Secondary outcomes (4)
  1. Progression-free survival (PFS)

    Progression-free survival (PFS), defined as the time from inclusion to progression or death.

    Measured: 18 months

  2. Overall survival (OS)

    Overall survival (OS), defined as the time from inclusion to death by any cause.

    Measured: 18 months

  3. Objective response rate (ORR)

    Objective response rate, defined as the proportion of patients who achieved a CR or PR according to the investigator-assessed RECIST v1.1 criteria.

    Measured: 18 months

  4. Safety of the trastuzumab/tucatinib combination

    Adverse Events (AEs) and Serious Adverse Events (SAEs), per CTCAE v5.0, considered by the investigator as related to trastuzumab or tucatinib.

    Measured: 18 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted25 Sep 2025
  2. Study start31 Jan 2026 (estimated)
  3. Primary completion7 Dec 2028 (estimated)
  4. Study completion8 Jun 2029 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Model description
The H3RAKLES single-arm phase II trial will evaluate the combination of tucatinib, a HER2 TKI, and trastuzumab, a HER2-directed antibody, with a Bayesian design in patients with a HER2-not amplified metastatic or unresectable breast cancer harboring an activating ERBB3 mutation.
Masking
None (open label)
Enrolment
20 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07193394
Sponsor's protocol ID
IC 2024-01
Other IDs
2024-519624-24-00
Acronym
H3RAKLES
Status last verified
Feb 2026
First submitted
12 Sep 2025
Last updated
23 Feb 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Sponsor will share de-identified data sets. Documents generated under the project will be disseminated in accordance with Institut Curie policies. IPD sharing Supporting Information: cases à cocher Study Protocol, Statistical Analysis Plan (SAP).

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Tucatinib (ONT-380) and Trastuzumab (Herceptin) in people with Metastatic Breast Cancer ( HER2 Negative) and Unresectable Breast Cancer, run by Institut Curie at 9 sites in France.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 17 inclusion and 30 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 23 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 9 sites in France. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Sandra Clinical Project Manager (+33156245944, drci.promotion@curie.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Clinical benefit rate (CBR) (time frame: 24 weeks). It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Feb 2026.

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