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Purpose

This is a prospective study to assess the impact of biomarker driven, early therapeutic switching and delayed imaging with the incorporation of DiviTum® serum TK1 activity ("DiviTum® TKa") in patients with HR positive, HER-2 negative metastatic or unresectable breast cancer. Patients will receive first-line treatment with a CDK4/6 inhibitor (CDK4/6i) and endocrine therapy. All patients will have blood drawn for thymidine kinase activity (TKa) testing at baseline and at C1D15. Patients who are found to have a lack of TKa suppression at C1D15 will be recommended to switch to an alternative therapy. Patients with suppressed C1D15 TKa levels will continue on CDK4/6i and endocrine therapy until clinical progression. Patients with TKa which remains suppressed will be recommended to delay restaging scans from 24 weeks to 36 weeks. The investigators hypothesize that a patient's TKa level at C1D15 is prognostic for progression-free survival (PFS) on a CDK4/6 inhibitor and early therapeutic switching in patients with a lack of C1D15 TKa suppression will be associated with prolonged PFS.

Conditions

Eligibility

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

Inclusion Criteria

  • Patients - Diagnosis of metastatic or advanced unresectable invasive breast cancer that is hormone receptor-positive (HR+) and HER2-negative. - Planned to initiate standard of care first-line therapy with FDA-approved endocrine therapy plus CDK4/6 inhibitor for the stated diagnosis at the time of study enrollment. Ribociclib is the preferred CDK4/6 inhibitor. In the event this drug cannot be obtained due to insurance authorization or if there are specific side effect profile concerns from the treating physician, an alternative CDK4/6 inhibitor is allowed. - Any prior therapy for early stage breast cancer is allowed, including endocrine therapy and chemotherapy. - Prior receipt of adjuvant CDK 4/6 inhibitor therapy is permitted provided therapy completion occurred > 12 months prior to study enrollment. - Presence of RECIST-evaluable disease. Patients with bone-only disease are eligible. - At least 18 years of age. - ECOG performance status ≤ 2 - Post-menopausal status, defined as one of the following: - Age ≥ 60 years - Age < 60 with intact uterus and amenorrhea for 12 consecutive months or more - Status post bilateral oophorectomy, total hysterectomy - Pre- or peri-menopausal with suppressed ovarian function by use of GnRH agonist/antagonist or surgical bilateral oophorectomy - Ability to understand and willingness to sign an IRB approved written informed consent document (or that of legally authorized representative, if applicable).

Exclusion Criteria

  • Patients - Receipt of any prior cytotoxic chemotherapy line for metastatic disease. There will be no limit to chemotherapy use in the neoadjuvant or adjuvant setting. - Patients with a prior or concurrent malignancy are excluded unless that malignancy's natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial. - Concurrent participation in any investigational therapeutic trial for treatment of metastatic breast cancer. Eligibility Criteria - Physicians - Medical Oncologist at Siteman Cancer Center. - Treating patients with metastatic or advanced unresectable breast cancer. - Willing to complete Physician Surveys during participation.

Study Design

Phase
N/A
Study Type
Interventional
Allocation
Non-Randomized
Intervention Model
Parallel Assignment
Primary Purpose
Treatment
Masking
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Experimental
TKa suppressed at Cycle 1 Day 15 		- Study visits will occur at Baseline, Week 2 (C1D15), C2D1, C4D1, and clinical progression. Blood serum samples will be collected and analyzed using DiviTum® TKa at each of these dictated time points. - Patients with suppressed TKa levels at C1D15 will continue on CDK4/6i + endocrine therapy until clinical progression. There will be an option to elongate the time between restaging scans from Q3M to Q6M if TKa remains suppressed in this group. Physicians may repeat TKa in 2 weeks if TKa rise is noted and if TKa again becomes suppressed, may delay imaging. These patients will undergo TKa level monitoring at C2D1, C4D1, every 3 months thereafter, and at the time of clinical progression. The feasibility endpoint relates specifically to the Week 24 imaging time point.
  • Device: DiviTum® TKa assay
    Will be utilized for determination of serum enzymatic activity of TK1 according to the manufacturer's instructions
  • Drug: CDK4/6 + Endocrine therapy
    FDA-approved endocrine therapy plus CDK4/6 inhibitor. Ribociclib is the preferred CDK4/6 inhibitor. In the event this drug cannot be obtained due to insurance authorization or if there are specific side effect profile concerns from the treating physician, an alternative CDK4/6 inhibitor is allowed.
Experimental
TKa unsuppressed at Cycle 1 Day 15 		- Study visits will occur at Baseline, Week 2 (C1D15), C2D1, C4D1, and clinical progression. Blood serum samples will be collected and analyzed using DiviTum® TKa at each of these dictated time points. - Patients with lack of TKa suppression at C1D15 (defined as >145 DuA) will be recommended to switch to an alternative therapy after compliance with the medication is ensured (by pill count) and potential drug-drug interactions are reviewed. These patients will have TKa samples drawn at initiation of second-line therapy and on the first day of subsequent cycles until progression.
  • Device: DiviTum® TKa assay
    Will be utilized for determination of serum enzymatic activity of TK1 according to the manufacturer's instructions
  • Drug: CDK4/6 + Endocrine therapy
    FDA-approved endocrine therapy plus CDK4/6 inhibitor. Ribociclib is the preferred CDK4/6 inhibitor. In the event this drug cannot be obtained due to insurance authorization or if there are specific side effect profile concerns from the treating physician, an alternative CDK4/6 inhibitor is allowed.
No Intervention
Physicians 		-Physicians will be asked to complete surveys as follows: - Physician Survey 1 for patients in the TKa C1D15 Suppressed group who have the option to delay the Week 24 scan at Week 24 - Physician Survey 2 for patients in the TKa C1D15 Unsuppressed group at C1D15 (after TKa results have returned but before switching therapy)

Recruiting Locations

Washington University in St. Louis and nearby locations

Washington University School of Medicine
St Louis 4407066, Missouri 4398678 63110
Contact:
Katherine Clifton, M.D.
314-273-3712
k.clifton@wustl.edu

More Details

NCT ID
NCT05977036
Status
Recruiting
Sponsor
Washington University School of Medicine

Study Contact

Katherine Clifton, M.D.
314-273-3712
k.clifton@wustl.edu

Notice

Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.