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Breast CancerPhase 1/2ELONANCT05618613

Study of Elacestrant in Combination With Onapristone in Patients With Advanced or Metastatic Breast Cancer

A Phase 1/2 study testing Elacestrant and Onapristone in people with Breast Cancer, run by Context Therapeutics Inc. at 3 sites in United States.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record
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Trial summary

This is a multicenter, Phase 1b-2 study of elacestrant in combination with onapristone in patients with advanced/metastatic ER+/PgR+/HER2- breast cancer. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Breast Cancer
What is being tested?
Elacestrant and Onapristone
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
4 participants
Where
3 sitesUnited States
Study dates
2 Dec 2022to 23 Jun 2023
Phase
Phase 1/2
Are there results?
Yes, posted in the registrySummary in the doctors' view

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

  • Women or men aged ≥18 years, at the time of informed consent signature. Note: Pre- and peri-menopausal women must receive goserelin for at least one month prior to initiating trial therapy, during the trial, and for at least one month after end of trial therapy. Men must receive triptorelin for at least one month prior to initiating trial therapy, during the trial and for at least one month after end of trial therapy.
  • Histopathologically or cytologically confirmed ER+, PgR+, HER2-, breast cancer, per local laboratory, as per the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines (Allison et al, 2020). Note: In the context of this trial, ER and PgR status will be considered positive if ≥10% of tumor cells demonstrate positive nuclear staining by immunohistochemistry.
  • At least one measurable lesion as per RECIST version 1.1. Note: Patients with stable brain or subdural metastases are allowed if the patient has completed local therapy and has discontinued the use of corticosteroids for at least 4 weeks before starting treatment in this study. Any signs (e.g., radiologic) or symptoms of brain metastases must be stable for at least 4 weeks before starting study treatment.
  • Prior therapy with an aromatase inhibitor or fulvestrant + a CDK4/6 inhibitor in the metastatic setting or in the adjuvant setting if within 12 months of last dose of adjuvant therapy. Note: Prior therapy with everolimus is allowed.
  • ECOG performance status of 0 or 1.
  • Patient has adequate bone marrow and organ function, as defined by the following laboratory values:
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  • Absolute neutrophil count (ANC) ≥1.5 × 109/L,
  • Platelets ≥100 × 109/L,
  • Hemoglobin ≥9.0 g/dL,
  • Potassium, sodium, calcium (corrected for serum albumin), and magnesium CTCAE grade ≤1,
  • Cockcroft-Gault-based creatinine clearance ≥50 mL/min. Note: Creatinine clearance (male) = ([140-age in years] × weight in kg)/ ([serum creatinine in mg/dL] × 72) Creatinine clearance (female) = (0.85 × [140-age in years] × weight in kg)/ ([serum creatinine in mg/dL] × 72),
  • Serum albumin ≥3.0 g/dL (≥30 g/L),
  • In absence of liver metastases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3.0 × ULN. If the patient has liver metastases, ALT and AST ≤5 × ULN,
  • Total serum bilirubin <1.5 × ULN except for patients with Gilbert's syndrome who may be included if the total serum bilirubin is ≤3.0 × ULN or direct bilirubin ≤1.5 × ULN.

Who cannot join

  • Active or newly diagnosed CNS metastases, including meningeal carcinomatosis.
  • Breast cancer treatment-naïve patients in the metastatic setting.
  • Prior therapy with elacestrant, onapristone, or chemotherapy in the metastatic setting.
  • Patient has a concurrent malignancy or history of invasive malignancy within 3 years of enrollment, with the exception of basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix that has completed curative therapy.
  • Uncontrolled significant active infections.
  • Patients with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection must have undetectable viral load during screening.
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  • Patients known to be HIV+ are allowed as long as they have undetectable viral load at baseline.
  • Major surgery within 4 weeks before starting trial therapy.
  • Inability to take oral medication, or history of malabsorption syndrome or any other uncontrolled gastrointestinal condition.
  • Females of childbearing potential who:
  • Within 28 days before study entry, did not use a highly effective method of contraception.
  • Do not agree to use a highly effective method of contraception throughout the entire study period and for 28 days after trial therapy discontinuation.
  • Males who do not agree to abstain from donating sperm, or to use a highly effective method of contraception, during the course of the treatment period and for 28 days thereafter.
  • Known intolerance to either study drug or any of the excipients.
  • Patient is currently receiving or received any of the following medications prior to first dose of trial therapy:
  • Known strong or moderate inducers or inhibitors of cytochrome P450 (CYP) 3A4 within 14 days or 5 half-lives, whichever is shorter, (Refer to http://medicine.iupui.edu/clinpharm/ddis/),
  • Herbal preparations/medications within 7 days. These include, but are not limited to, St. John's wort, kava, ephedra (ma huang), gingko biloba, dehydroepiandrosterone (DHEA), yohimbe, saw palmetto, and ginseng.
  • Investigational anti-cancer therapy with 21 days or 5 half-lives, whichever is shorter.
  • Vaccination, including but not limited to vaccination against COVID-19, during the 7 days prior to randomization.
  • Evidence of ongoing alcohol or drug abuse.

Trial locations and contacts

3 sites in 1 country.

United States3 sites

  • Sarah Cannon Research Institute

    Nashville, Tennessee, 37203

  • Cancer Treatment Centers of America - Western Regional Medical Center

    Phoenix, Arizona, 85338

  • Cancer Treatment Centers of America - Midwestern Regional Center

    Zion, Illinois, 60099

Other trials in United States

About this study

Official title: An Open-Label, Phase 1b-2 Study of Elacestrant, in Combination With Onapristone in Patients With Estrogen Receptor-Positive, Progesterone Receptor-Positive, HER2-negative Advanced or Metastatic Breast Cancer (ELONA)

This is a multicenter, Phase 1b-2 study of elacestrant in combination with onapristone in patients with advanced/metastatic ER+/PgR+/HER2- breast cancer.

Read the detailed description

This is a multicenter, phase 1b-2 trial. The phase 1b part of the trial is open label and aims to determine the recommended Phase 2 dose (RP2D) of onapristone and elacestrant when administered together. The Phase 2 part of the trial will evaluate the efficacy and safety of this combination in patients with ER+/PgR+/HER2- advanced/metastatic breast cancer after prior therapy with a CDK4/6 inhibitor.

Conditions
Breast Cancer
Being tested
Elacestrant, Onapristone
Medical subject headings
Breast Neoplasms

What participants receive

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

  • ElacestrantDrug

    Also called RAD1901

    Elacestrant 200mg, 300mg, or 400mg once daily oral dosing in cycles of 28 days.

  • OnapristoneDrug

    Onapristone 40mg or 50mg twice daily oral dosing in cycles of 28 days.

Study groups in NCT05618613
Study groupRoleWhat they receive
Elacestrant / OnapristoneExperimentalElacestrant and Onapristone combination
Receives: Drug: Elacestrant; Drug: Onapristone

What is being measured

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

  1. Number of Participants With Dose-Limiting Toxicities (DLTs) During First Cycle

    DLTs were pre-specified toxicities occurring during Cycle 1 (28 days) and considered at least possibly related to study treatment, based on CTCAE criteria. Assessment of safety and tolerability to determine the recommended Phase 2 dose (RP2D). DLT defined as dose associated with <33% of patients experiencing DLT (≤1 patient out of 6 DLT-evaluable patients).

    Measured: First 28 days (Cycle 1)

  2. Objective Response Rate (ORR)

    ORR was defined as the proportion of patients achieving confirmed complete or partial response per RECIST v1.1; Phase 2 was not initiated, and no patients were enrolled.

    Measured: Assessed every 8 weeks until disease progression, up to approximately 6 months

Secondary outcomes (7)

  1. Adverse Events (AEs)

    Adverse events were collected from first dose through last safety assessment and graded using NCI CTCAE v5.0. Incidence and severity of AEs was collected.

    Measured: From first dose until 30 days after last dose (up to 183 days)

  2. Serious Adverse Events (SAEs)

    Serious Adverse events were collected from first dose through last safety assessment and graded using NCI CTCAE v5.0. Incidence and severity of SAEs was collected

    Measured: 183 days

  3. Evaluate the Maximum Plasma Concentration (Cmax) of Elacestrant as Well as Onapristone and Their Metabolites (Phase 1)

    AUC₀-ₜₐᵤ, Cₘₐₓ, Tₘₐₓ, and Cₜᵣₒᵤ for elacestrant, onapristone, and metabolites. PK samples were obtained from 2 patients at Cycle 1, Day 15 at the following timepoints: predose (hour 0), 1, 2, 3, 6, 8, 12, and 24 hours post-dose. Data was collected as represented below for 2 patients

    Measured: 15 Days

  4. Evaluate the Time of the Maximum Observed Plasma Concentration (Tmax) of Elacestrant as Well as Onapristone and Their Metabolites (Phase 1).

    AUC₀-ₜₐᵤ, Cₘₐₓ, Tₘₐₓ, and Cₜᵣₒᵤ for elacestrant, onapristone, and metabolites. PK samples were obtained from 2 patients at Cycle 1, Day 15 at the following timepoints: predose (hour 0), 1, 2, 3, 6, 8, 12, and 24 hours post-dose. Data was collected as represented below for 2 patients

    Measured: 15 Days

  5. Evaluate Duration of Response

    Time from first CR/PR until progression or death

    Measured: From first documented CR/PR until progression or death, up to 183 days

  6. Evaluate Clinical Benefit Rate

    Proportion of subjects achieving a best overall or complete response, or durable stable disease (duration is at least 23 weeks)

    Measured: 183 days

  7. Evaluate Progression-free Survival

    Time from the date of the first dose to the date of the first documentation of disease progression or death, whichever occurs first.

    Measured: 183 Days

Timeline

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

  1. First posted16 Nov 2022
  2. Study start2 Dec 2022
  3. Primary completion23 Jun 2023
  4. Study completion23 Jun 2023

Why it stopped: Sponsor decision to discontinue onapristone development.

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 1/2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
4 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05618613
Sponsor's protocol ID
ONA-XR-103
Acronym
ELONA
Status last verified
Jun 2026
First submitted
3 Nov 2022
Last updated
21 Jul 2026
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing Elacestrant and Onapristone in people with Breast Cancer, run by Context Therapeutics Inc. at 3 sites in United States.

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 14 inclusion and 20 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: stopped early, as of the sponsor's last update on 21 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 sites in United States. 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 combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

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?

Yes. Results are posted in the registry (first posted 21 Jul 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants With Dose-Limiting Toxicities (DLTs) During First Cycle (time frame: First 28 days (Cycle 1)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05618613.

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 21 Jul 2026.

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