Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2017-01
68Ga-PSMA-11 PET Imaging of Response to Androgen Receptor Inhibition: First Human Experience.
ABSTRACT
The purpose of this work was to evaluate the effect of androgen receptor (AR) inhibition on prostate-specific membrane antigen (PSMA) uptake imaged using Ga-PSMA-11 PET in a mouse xenograft model and in a patient with castration-sensitive prostate cancer.
METHODS
We imaged 3 groups of 4 mice bearing LNCaP-AR xenografts before and 7 d after treatment with ARN-509, orchiectomy, or control vehicle. Additionally, we imaged one patient with castration-sensitive prostate cancer before and 4 wk after treatment with androgen deprivation therapy (ADT). Uptake on pre- and posttreatment imaging was measured and compared.
RESULTS
PSMA uptake increased 1.5- to 2.0-fold in the xenograft mouse model after treatment with both orchiectomy and ARN-509 but not with vehicle. Patient imaging demonstrated a 7-fold increase in PSMA uptake after the initiation of ADT. Thirteen of 22 lesions in the imaged patient were visualized on PSMA PET only after treatment with ADT.
CONCLUSION
Inhibition of the AR can increase PSMA expression in prostate cancer metastases and increase the number of lesions visualized using PSMA PET. The effect seen in cell and animal models can be recapitulated in humans. A better understanding of the temporal changes in PSMA expression is needed to leverage this effect for both improved diagnosis and improved therapy.
Related Questions
Is there any information on how ADT affects the test operating characteristics?
New answer by Radiation Oncologist at Washington University School of Medicine (June 19, 2018)
As initial or relapse staging, ADT likely suppresses uptake of tracers and will lead to false negative staging scans. On the other hand, if patients become castrate resistant,...
Do you worry about false negatives on PET, CT, MRI if ADT is started before the scan? Scheduling scans can sometimes book 2-4 weeks out.
New answer by Medical Oncologist at Mary Lanning Healthcare Morrison Cancer Center/University of Nebraska Medical Center Adjunct Faculty (February 8, 2022)
It is important to evaluate both castration-sensitive and castration-resistant models and patients, short and long term ADT with various agents (e.g., short term ADT use of or...