RT Journal Article
SR Electronic
T1 Imaging Patients with Metastatic Castration-Resistant Prostate Cancer Using <sup>89</sup>Zr-DFO-MSTP2109A Anti-STEAP1 Antibody
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1517
OP 1523
DO 10.2967/jnumed.118.222844
VO 60
IS 11
A1 Carrasquillo, Jorge A.
A1 Fine, Bernard M.
A1 Pandit-Taskar, Neeta
A1 Larson, Steven M.
A1 Fleming, Stephen E.
A1 Fox, Josef J.
A1 Cheal, Sarah M.
A1 O’Donoghue, Joseph A.
A1 Ruan, Shutian
A1 Ragupathi, Govind
A1 Lyashchenko, Serge K.
A1 Humm, John L.
A1 Scher, Howard I.
A1 Gönen, Mithat
A1 Williams, Simon P.
A1 Danila, Daniel C.
A1 Morris, Michael J.
YR 2019
UL http://jnm.snmjournals.org/content/60/11/1517.abstract
AB Six-transmembrane epithelial antigen of prostate-1 (STEAP1) is a relatively newly identified target in prostate cancer. We evaluated the ability of PET/CT with 89Zr-DFO-MSTP2109A, an antibody that recognizes STEAP1, to detect lesions in patients with metastatic castration-resistant prostate cancer (mCRPC). Methods: Nineteen mCRPC patients were prospectively imaged using approximately 185 MBq/10 mg of 89Zr-DFO-MSTP2109A. 89Zr-DFO-MSTP2109A PET/CT images obtained 4–7 d after injection were compared with bone and CT scans. Uptake in lesions was measured. Fifteen patients were treated with an antibody–drug conjugate (ADC) based on MSTP2109A; ADC treatment–related data were correlated with tumor uptake by PET imaging. Bone or soft-tissue biopsy samples were evaluated. Results: No significant toxicity occurred. Excellent uptake was observed in bone and soft-tissue disease. Median SUVmax was 20.6 in bone and 16.8 in soft tissue. Sixteen of 17 lesions biopsied were positive on 89Zr-DFO-MSTP2109A, and all sites were histologically positive (1 on repeat biopsy). Bayesian analysis resulted in a best estimate of 86% of histologically positive lesions being true-positive on imaging (95% confidence interval, 75%–100%). There was no correlation between SUVmax tumor uptake and STEAP1 immunohistochemistry, survival after ADC treatment, number of ADC treatment cycles, or change in prostate-specific antigen level. Conclusion: 89Zr-DFO-MSTP2109A is well tolerated and shows localization in mCRPC sites in bone and soft tissue. Given the high SUV in tumor and localization of a large number of lesions, this reagent warrants further exploration as a companion diagnostic in patients undergoing STEAP1-directed therapy.