Study Locations (11 sites)
Centre Georges François Leclerc, Dijon, 21079 France
CHU de Limoges, Limoges, 87042 France
Centre Léon Bérard, Lyon, 69373 France
Institut Paoli Calmettes, Marseille, 13273 France
Institut Régional du Cancer de Montpellier, Montpellier, 34298 France
Centre Antoine Lacassagne, Nice, 06189 France
Institut Curie, Paris, 75005 France
Hôpital Tenon, Paris, 75020 France
Institut de Cancérologie de l'Ouest, Saint-Herblain, 44805 France
Institut Claudius Regaud, Toulouse, 31059 France
Eligibility Criteria
Inclusion Criteria:
* Adults with histologically-confirmed HER2 negative, unresectable locally advanced or metastatic breast cancer that is hormone receptor positive (HR+) at the time of the first breast cancer diagnosis
* Participants with a documented radiologic unresectable or metastatic progression
* Participants may have received anthracyclines and taxanes as (neo) adjuvant treatment and must have received one line of chemotherapy for Advanced breast cancer (ABC), but not more than one line. Participants must have a clinically or radiologically documented evidence of tumor progression on or after cyclin dependent kinase 4/6 (CDK 4/ 6) inhibitor combined with endocrine therapy. Previous treatments with PI3K inhibitors, mTOR inhibitors, AKT-inhibitors and poly ADP ribose polymerase (PARP)-inhibitors are allowed
* Participants must have a tumor site easily accessible to biopsy (with exception of bone metastasis)
* Participants must have at least one radiologically measurable lesion (different from the biopsy site)
* Participants must have an ECOG PS equals to 0 or 1
* Participants must have a life expectancy of 12 weeks or more
* Participants must have adequate bone marrow reserve and organ function, based on local laboratory data within 14 days prior to Cycle 1, Day 1
* Female patients of reproductive/childbearing potential must have a negative pregnancy test at screening (serum test within 14 days or urine test within 72 hours of enrollment). A positive urine pregnancy test result must be confirmed by a serum test. Patients must agree to use a highly effective form of contraception or avoid intercourse during and upon completion of the study and for at least 7 months after the last dose of study drug.
The following contraception methods are considered highly effective:
1. Hormonal or nonhormonal intrauterine device (IUD)
2. Progestogen-only subdermal contraceptive implant
3. Bilateral tubal occlusion
4. Vasectomized partner
5. Complete sexual abstinence defined as refraining from heterosexual intercourse during and upon completion of the study and for at least 7 months for females after the last dose of study drug.
Periodic abstinence (calendar, symptothermal, post-ovulation methods) is not an acceptable method of contraception. Penile/external condoms for male partners must be used in addition to the female patient's hormonal contraception for the duration treatment intervention and until 7 months following the last dose of trial intervention. Female patients must not donate, or retrieve for their own use, ova from the time of screening and throughout the study treatment period, and for at least 7 months after the final study drug administration.
* A male participant capable of producing sperm is eligible to participate if he agrees to the following during the intervention period and for at least the time needed to eliminate each trial intervention. The length of time required to continue contraception after last dose for each trial intervention is 4 months. Avoid donating sperm. Note: Preservation of sperm should be considered prior to enrollment/randomization in this trial. Use a penile/external condom when having penile-vaginal intercourse with a nonparticipant of childbearing potential, PLUS partner use of an additional contraceptive method (see below), as a condom may break or leak:
1. Progestogen-only contraceptive implant
2. Hormonal or nonhormonal IUD
3. Bilateral tubal occlusion (includes tubal ligation)
4. Combined (estrogen- and progestogen-containing) hormonal contraception (oral, intravaginal, transdermal, injectable)
5. Progestogen-only hormonal contraception (oral, injectable)
6. Progesterone-only hormonal contraception where inhibition of ovulation is not the primary mode of action
7. Cervical cap, diaphragm, or sponge with spermicide Contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
If the contraception requirements in the local label for any of the trial interventions are more stringent than the requirements above, the local label requirements are to be followed. Note: If the participant is azoospermic (vasectomized or secondary to medical cause, documented from the site personnel's review of the participant's medical records, medical examination, or medical history interview), no contraception is required.
Male participants must not freeze or donate sperm starting at screening and throughout the study period, and for at least 4 months after the final study drug administration
* Participant must understand, sign, and date the written ICF prior to any protocol-specific procedures performed. Participant should be able and willing to comply with study visits and procedure as per protocol
* Participant must be affiliated to a social security system or beneficiary of the same
Exclusion Criteria:
* Breast cancer amenable for resection or radiation therapy with curative intent
* Any history of interstitial lung disease (ILD), actual ILD, or a suspicion of an ILD
* Clinically severe pulmonary compromise (based on investigator's assessment) resulting from intercurrent pulmonary illnesses including, but not limited to:
1. Any underlying pulmonary disorder
2. Any autoimmune, connective tissue or inflammatory disorder with pulmonary involvement
3. OR prior pneumonectomy
* The use of chronic systemic corticosteroids at a dose superior to 10 mg daily of prednisone or equivalent or any form of immunosuppressive therapy prior to Cycle 1 Day 1. Participants who require use of bronchodilators, inhaled steroids, or local steroid injections may be included in the study
* Evidence of any leptomeningeal disease
* Evidence of corneal disease
* Any evidence of severe or uncontrolled systemic diseases including active bleeding diatheses, active infection, psychiatric illness/social situations, geographical factors, substance abuse, or other factors which in the investigator's opinion makes it undesirable for the participant to participate in the study or which would jeopardize compliance with the protocol
* Evidence of clinically active spinal cord compression or brain metastases defined as untreated and symptomatic, or requiring therapy with corticosteroids or anticonvulsants to control associated symptoms
* Exposure to prior systemic anticancer therapy (including investigational agents) within 4 weeks or 5 half-lives (whichever is shorter) before enrollment.
* Inadequate washout period prior to Cycle 1 Day 1, defined as:
1. Whole brain radiation therapy \<14 days or stereotactic brain radiation therapy \<7 days.
2. Immune checkpoint inhibitor therapy \<21 days
3. Hormonal therapy \<21 days
4. Major surgery (excluding placement of vascular access) \<28 days.
5. Radiotherapy treatment to more than 30% of the bone marrow or with a wide field of radiation \<28 days or palliative radiation therapy \<14 days.
6. Chloroquine or hydroxychloroquine ≤ 14 days
7. Live virus vaccination \<28 days.
* Prior treatment with an anti-HER3 antibody and/or ADC containing an exatecan derivative that is a topoisomerase I inhibitor
* Participants with a grade equals or greater than 2 unresolved toxicities from previous anticancer therapy (other than alopecia)
* A history of severe hypersensitivity reactions to either the drug substances or inactive ingredients of U3-1402, or to other monoclonal antibodies
* Any evidence of primary malignancy other than locally advanced or metastatic lung cancer within three years prior to Cycle 1 Day 1, except adequately resected non-melanoma skin cancer, curatively treated in-situ disease, or other solid tumors curatively treated
* Uncontrolled or significant cardiovascular disease prior to Cycle 1 Day :
1. Corrected QT interval higher than 470 ms for females and 450 ms for males according to Fridericia's formula (QTcF) and assessed based on triplicate ECGs, approximately 1 minute apa