Kevin Slawin MD, Presenter: Nothing to Disclose

Peter Tenke, Abstract Co-Author: Nothing to Disclose

Steven Joniau, Abstract Co-Author: Nothing to Disclose

William Ellis, Abstract Co-Author: Nothing to Disclose

Boris Alekseev, Abstract Co-Author: Nothing to Disclose

Istvan Buzogany, Abstract Co-Author: Nothing to Disclose

Sergey Mishugin, Abstract Co-Author: Nothing to Disclose

Eric Klein, Abstract Co-Author: Nothing to Disclose

Josef Stolz, Abstract Co-Author: Nothing to Disclose

Vladimir Student, Abstract Co-Author: Nothing to Disclose

Vsevolod Matveev, Abstract Co-Author: Nothing to Disclose

Bela Koves, Abstract Co-Author: Nothing to Disclose

John Babich PhD, Abstract Co-Author: Nothing to Disclose

Hagop Youssoufian, Abstract Co-Author: Nothing to Disclose

Nancy Stambler, Abstract Co-Author: Nothing to Disclose

Thomas Armor, Abstract Co-Author: Nothing to Disclose

Robert Israel MD, Abstract Co-Author: Nothing to Disclose

Technetium-99m trofolastat chloride is a novel small molecule SPECT radiotracer with high affinity binding to the external domain of prostate specific membrane antigen (PSMA), an enzyme with high expression in PCa. We conducted an open-label, multicenter study (NCT01667536). The primary endpoint was the ability of trofolastat to detect PCa within the prostate gland (PG). Secondary endpoints included detection in PLNs and comparison to MRI.

Patients (pts) with PCa scheduled for RP with ePLND at high risk (≥cT3 or Godoy nomogram score ≥130) for PLN involvement were eligible. Within 30 days of screening, pts required a bone scan and pelvic MRI. Enrolled pts received trofolastat and SPECT/CT imaging 3-6 hrs later. 3 SPECT/CT readers and one MRI reader, blinded to clinical information, evaluated all available image data. Results were compared to on-site histopathology assessments of RP and ePLN surgical specimens using a common anatomic template. Target to background (T:B) ratio within the PG was measured on the SPECT/CT and compared to Gleason Score (GS).

Enrollment has been completed and data is available for the first 54 of 105 pts. A majority of SPECT/CT readers correctly identified the presence of primary PCa in 49/54 (91%) evaluable pts. In 47 pts who had both MR as well as trofolastat scans, readers correctly identified PCa in 40/47 (85%) and 42/47 (89%), respectively. In 37 pts with no prior hormone therapy, GS following RP ranged from 3+4 to 5+5 and significantly correlated with maximum T:B values (r=0.54 p<001). In 17 pts treated with neoadjuvant hormonal therapy, T:B was lower than untreated pts (p<0.005).

Trofolastat SPECT/CT detected PCa within the PG in 49 of the first 54 (91%) of evaluable high-risk pts prior to surgery. Uptake of trofolastat correlated significantly with GS obtained from post-RP histopathology in untreated pts and may provide information regarding disease aggressiveness using a non-invasive technique in high-risk pts prior to surgery. Final results, analyses of secondary endpoints, pelvic lymph nodes, and comparative performance vs. MRI from this study will be presented.

Accurate detection and characterization of prostate cancer should enhance optimal delivery of therapy. Tc-99m trofolastat has shown clinical relevance in studies to date.

Slawin, K, Tenke, P, Joniau, S, Ellis, W, Alekseev, B, Buzogany, I, Mishugin, S, Klein, E, Stolz, J, Student, V, Matveev, V, Koves, B, Babich, J, Youssoufian, H, Stambler, N, Armor, T, Israel, R, A Phase 2 Study of 99mTc-trofolastat Chloride SPECT to Identify and Localize Prostate Cancer (PCa) in Patients undergoing Radical Prostatectomy (RP) and Extended Pelvic Lymph Node (ePLN) Dissection Compared to Histopathology: An Interim Analysis.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011302.html