FDHT PET and Bicalutamide in Metastatic Breast Cancer
Status:
Completed
Trial end date:
2019-11-25
Target enrollment:
Participant gender:
Summary
Rationale: The purpose is to evaluate whether non-invasive in vivo imaging of androgen
receptor (AR) presence in metastatic breast cancer patients by means of
18F-fluoro-dihydrotestosterone positron emission tomography (FDHT-PET) can be used to predict
(early) treatment response to, and optimal dosing of, the anti androgen bicalutamide. The
ultimate goal is to contribute to optimal selection of breast cancer patients for anti
androgen treatment. Objective: Feasibility to detect a diffrence in uptake on 18F-FDHT scan
after 6 weeks of treatment with bicalutamide in metastatic breast cancer patients. Secondary
Objectives: to describe whether changes in 18F-FDHT tracer uptake after six weeks associates
with response to bicalutamide, to describe whether changes in AR availability are different
for breast cancer subgroups during treatment with bicalutamide and to describe whether
18F-FDHT tracer uptake is influenced by the amount of AR tumor expression. Study design: This
is a single arm, one stage feasibility study, which will be executed in the University
Medical Center Groningen, The Netherlands. The primary endpoint of the study is to evaluate
the difference in 18F-FDHT uptake in tumor lesions after 6 weeks of bicalutamide treatment in
patients with AR-positive metastatic breast cancer. Patients will be treated with
bicalutamide until progression or unacceptable toxicity is encountered. Study population: The
investigators will include 20 postmenopausal metastatic breast cancer patients with an AR
positive, HER2 negative tumor. Patients should be restaged clinically with bone scintigraphy
and CT scan within a 6 week timeframe of the PET examinations. Intervention: All patients
will receive a baseline FDHT-PET scan and start with bicalutamide treatment 150mg daily.
During follow-up patients will receive one FDHT-PET scan after 6 weeks. Treatment with
bicalutamide will continue until progression or unacceptable toxicity is encountered. Main
study endpoint: The percent difference in 18F-FDHT uptake in tumor lesions after 6 weeks of
monotherapy bicalutamide. A minimum decrease of 20% in 18F-FDHT uptake after 6 weeks compared
to baseline uptake with an α of 0.05 and a power of 80%, is considered clinical significant.