Evaluating RGT-419B for advanced breast cancer treatment

First-in-Human, Escalating Oral Dose Study of RGT-419B Given Alone and With Endocrine Therapy in Subjects With Hormone Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative Advanced/Metastatic Breast Cancer

This study is testing a new drug called RGT-419B to see if it can help people with advanced breast cancer who haven't responded to previous treatments.

Quick facts

• Phase: PHASE1
• Study type: Interventional
• Enrollment: 64 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Regor Pharmaceuticals Inc. (industry)
• Drugs / interventions: chemotherapy, radiation
• Locations: 8 sites (La Jolla, California and 7 other locations)
• Trial ID: NCT05304962 on ClinicalTrials.gov

What this trial studies

This phase I, First-in-Human study aims to assess the safety, tolerability, pharmacokinetics, and preliminary efficacy of RGT-419B, both as a standalone treatment and in combination with hormonal therapy, for patients with HR-positive, HER2-negative advanced or metastatic breast cancer. Participants must have experienced disease progression after prior treatment with a CDK4/6 inhibitor and hormonal therapy. The study will involve oral administration of RGT-419B to determine its effectiveness in this patient population.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with HR-positive, HER2-negative advanced or metastatic breast cancer that has progressed after prior CDK4/6 inhibitor therapy.

Not a fit: Patients who have not received prior CDK4/6 inhibitor therapy or those with HER2-positive breast cancer may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients with advanced breast cancer who have limited treatment alternatives.

How similar studies have performed: Other studies have shown promise with similar approaches, but this specific combination is being evaluated for the first time.

Eligibility criteria

Inclusion Criteria:

1. Male or female \>/= 18 years old
2. ECOG Performance Status 0 to 1
3. Subjects must have histologically or cytologically confirmed diagnosis of ER+, HER2- ABC consistent with ASCO CAP guidelines that is locally advanced and unresectable (Stage III) or metastatic (Stage IV) BC.
4. Measurable AND evaluable lesions at baseline per RECIST v1.1.
5. Eligible subjects must meet all of the following criteria:

   * Progression after receiving 1 line of prior cyclin-dependent kinase 4 and 6 inhibitor (CDK4/6i) therapy combined with HT in the MBC setting (up to 1 additional line of CDK4/6i is permitted in the post-surgical adjuvant setting);

     * Subjects must have received therapy for ≥3 months in the MBC setting, or for ≥6 months in the adjuvant setting, prior to progression
   * Progression after ≤3 lines of prior HT therapy (regardless of whether it is HT alone or in combination with other therapies)

     * Prior HT combination agents, including SERD, SERM or AI, must have received formal approval by regulatory agency.
   * ≤ 1 prior line of chemotherapy in the metastatic setting
6. Adequate organ function
7. Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

1. Presence of visceral metastases with severe organ dysfunction as evidence by signs and symptoms, laboratory studies, lymphangitic spread and/or rapid progression of disease
2. Pregnant or planning to become pregnant
3. Prior irradiation to \>25% of the bone marrow and/or inadequate bone marrow function or evidence of clinically significant end-organ damage
4. Major surgery, chemotherapy, targeted therapy, experimental agents, or radiation within 14-28 days prior to Cycle 1, Day 1
5. Active, serious medical condition that is not well controlled with locally approved medications allowed by the protocol
6. History of allergic reactions attributed to compounds of similar chemical or biologic composition to the drugs used in the study

Where this trial is running

La Jolla, California and 7 other locations

• University of California, San Diego — La Jolla, California, United States (RECRUITING)
• University California, Los Angeles — Los Angeles, California, United States (RECRUITING)
• Hem-Onc Associates of the Treasure Coast — Port Saint Lucie, Florida, United States (ACTIVE_NOT_RECRUITING)
• Moffitt Cancer Center — Tampa, Florida, United States (RECRUITING)
• Emory University — Atlanta, Georgia, United States (RECRUITING)
• Massachusetts General Hospital — Boston, Massachusetts, United States (RECRUITING)
• Washington University School of Medicine — St Louis, Missouri, United States (RECRUITING)
• New York Cancer and Blood Specialists — Port Jefferson Station, New York, United States (RECRUITING)

Study contacts

• Study coordinator: Joanna Dojillo, MSc

Conditions: Breast Cancer