Phase IB Study to Evaluate RAD1901 on the Availability of Estrogen Receptor Binding Sites in Metastatic Breast Cancer

Study Overview
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Brief Summary
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The purpose of this study is to visualize and quantify ER-binding sites during treatment with Elacestrant (RAD1901)

Detailed Description
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The purpose of this study is to visualize and quantify ER-binding sites during treatment with Elacestrant (RAD1901) using 16α-18F-Fluoro-17β-estradiol (FES) positron emission tomography (PET) imaging

Official Title
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A Phase IB Study to Evaluate the Effect of RAD1901 on the Availability of Estrogen Receptor Binding Sites in Metastatic Breast Cancer Lesions Using 16α-18F-Fluoro-17β-Estradiol Positron Emission Tomography Imaging

Conditions
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Metastatic Breast Cancer

Intervention / Treatment
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* Drug: RAD1901


Participation Criteria
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Eligibility Criteria
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Key Inclusion Criteria: Patients with histologically-proven, ER-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced, inoperative, and/or mBC Tumor progression after ≥ 6 months of at least 1 line of hormonal systemic treatment (SERM, SERD, or aromatase inhibitor) in the metastatic setting Measurable disease according to Response Evaluation Criteria in Solid Tumours (RECIST) criteria v1.1 or clinically evaluable disease Greater than or equal to 18 years of age Patients must be post-menopausal Life expectancy >3 months Key Exclusion Criteria: Greater than 3 lines of endocrine therapy for metastatic disease. Prior anti-cancer treatment or investigational drug therapy within the following windows: Tamoxifen or fulvestrant therapy < 42 days before 1st 18FES-PET scan Any other anti-cancer endocrine therapy < 14 days before 1st dose of study drug Any chemotherapy < 28 days before 1st dose of study drug Any investigational drug therapy < 28 days or 3 half-lives (whichever is longer) prior to the 1st dose of study drug 2. Patients with untreated or symptomatic central nervous system (brain) metastases 3. Patients with known endometrial disorders, including evidence of endometrial hyperplasia, dysfunctional uterine bleeding, or cysts

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Elacestrant (formerly RAD1901)<br>To receive daily oral elacestrant | Drug: RAD1901<br>* RAD1901, a novel selective ER degrader (SERD)<br>* Other names: Elacestrant;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Effect of ER Binding after RAD1901 treatment | To determine the effect of RAD1901 treatment on the estrogen receptor (ER) expression and estradiol binding to the ER in lesions from patients with metastatic breast cancer (mBC) | 14 Days after the first dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation of FES uptake after RAD1901 treatment to clinical response | To determine if any changes in ER binding, as observed through FES uptake, correlate with clinical response | Every 8 weeks for to up 12 months of treatment | 
| Tumor response will be evaluated in patients with measurable or evaluable disease, using RECISTv1.1 guidelines | To determine if there is a tumor response to RAD1901 treatment | Every 8 weeks for to up 12 months of treatment | 
| Safety and Tolerability assessed in terms of adverse events, serious adverse events, ECG, physical examination, ECOG performance status, vital signs, and laboratory values | Characterization of the safety of RAD1901 in this patient population | Up to 30 days after the end of treatment | 
| Plasma concentrations of RAD1901 will be assessed at predefined intervals | Pharmacokinetic data will be collected. | Every 28 days for up to 3 cycles |