FIH Study of RGT-419B Alone and With Endocrine Therapy in HR-Positive, HER2-Negative Advanced/Metastatic Breast Cancer

Purpose

This is a phase I, First-in-Human (FIH), open-label study to evaluate the safety, tolerability, pharmacokinetic (PK) profile, and preliminary efficacy of RGT-419B administered orally as monotherapy OR in combination with Hormonal Therapy in subjects with HR+, HER2- locally advanced and unresectable (Stage III) or metastatic (Stage IV) breast cancer whose disease has progressed during prior therapy with an approved CDK4/6i plus hormonal therapy.

Condition

  • Breast Cancer

Eligibility

Eligible Ages
Over 18 Years
Eligible Genders
All
Accepts Healthy Volunteers
No

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

Study Design

Phase
Phase 1
Study Type
Interventional
Allocation
Non-Randomized
Intervention Model
Sequential Assignment
Intervention Model Description
There will be two study arms opened sequentially to the same patient population. Arm A is RGT-419B alone (singlet). Arm B is RGT-419B + Hormonal Therapy (doublet) and will follow completion of Arm A.
Primary Purpose
Treatment
Masking
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Experimental
Arm A
RGT-419B given alone as monotherapy
  • Drug: RGT-419B
    oral capsules
Experimental
Arm B
RGT-419B in combination with Hormonal Therapy
  • Drug: RGT-419B in combination with hormonal therapy
    RGT-419B in combination with hormonal therapy (Selective Estrogen Receptor Degrader, Selective Estrogen Receptor Modulator, or Aromatase Inhibitor)

Recruiting Locations

Massachusetts General Hospital
Boston, Massachusetts 02142
Contact:
Amber Newton
617-726-1634
ANEWTON3@mgh.harvard.edu

More Details

Status
Recruiting
Sponsor
Regor Pharmaceuticals Inc.

Study Contact

Joanna Dojillo, MSc
617-315-9070
joanna.dojillo@regor.com