Preliminary Evaluation of 68Ga-P16-093, a PET Radiotracer Targeting Prostate-Specific Membrane Antigen in Prostate Cancer

Hwan Lee; Joshua S Scheuermann; Anthony J Young; Robert K Doot; Margaret E Daube-Witherspoon; Erin K Schubert; Matthew A Fillare; David Alexoff; Joel S Karp; Hank F Kung; Daniel A Pryma

doi:10.1007/s11307-022-01720-6

Preliminary Evaluation of ⁶⁸Ga-P16-093, a PET Radiotracer Targeting Prostate-Specific Membrane Antigen in Prostate Cancer

Mol Imaging Biol. 2022 Oct;24(5):710-720. doi: 10.1007/s11307-022-01720-6. Epub 2022 Mar 29.

Affiliations

¹ Department of Radiology, University of Pennsylvania Perelman School of Medicine, 3400 Spruce Street, Philadelphia, PA, 19104, USA.
² Five Eleven Pharma Inc., Philadelphia, PA, 19104, USA.
³ Department of Radiology, University of Pennsylvania Perelman School of Medicine, 3400 Spruce Street, Philadelphia, PA, 19104, USA. DPryma@pennmedicine.upenn.edu.

PMID: 35349040
DOI: 10.1007/s11307-022-01720-6

Abstract

Purpose: Prostate-specific membrane antigen (PSMA) is a promising molecular target for imaging of prostate adenocarcinoma. ⁶⁸Ga-P16-093, a small molecule PSMA ligand, previously showed equivalent diagnostic performance compared to ⁶⁸Ga-PSMA-11 PET/CT in a pilot study of prostate cancer patients with biochemical recurrence (BCR). We performed a pilot study for further characterization of ⁶⁸Ga-P16-093 including comparison to conventional imaging.

Procedures: Patients were enrolled into two cohorts. The biodistribution cohort included 8 treated prostate cancer patients without recurrence, who underwent 6 whole body PET/CT scans with urine sampling for dosimetry using OLINDA/EXM. The dynamic cohort included 15 patients with BCR and 2 patients with primary prostate cancer. Two patients with renal cell carcinoma were also enrolled for exploratory use. A dynamic PET/CT was followed by 2 whole body scans for imaging protocol optimization based on bootstrapped replicates. ⁶⁸Ga-P16-093 PET/CT was compared for diagnostic performance against available ¹⁸F-fluciclovine PET/CT, ^99mTc-MDP scintigraphy, diagnostic CT, and MRI.

Results: ⁶⁸Ga-P16-093 deposited similar effective dose (0.024 mSv/MBq) and lower urinary bladder dose (0.064 mSv/MBq) compared to ⁶⁸Ga-PSMA-11. The kidneys were the critical organ (0.290 mSv/MBq). While higher injected activities were preferable, lower injected activities at 74-111 MBq (2-3 mCi) yielded 80% retention in signal-to-noise ratio. The optimal injection-to-scan interval was 60 min, with acceptable delay up to 90 min. ⁶⁸Ga-P16-093 PET/CT showed superior diagnostic performance over conventional imaging with overall patient-level lesion detection rate of 71%, leading to a change in management in 42% of the patients.

Conclusions: Based on its favorable imaging characteristics and diagnostic performance in prostate cancer, ⁶⁸Ga-P16-093 PET/CT merits further investigation in larger clinical studies.

Keywords: Biochemical recurrence; Positron emission tomography computed tomography; Prostate cancer; Prostate-specific membrane antigen.

Publication types

Research Support, Non-U.S. Gov't
Research Support, N.I.H., Extramural

MeSH terms

Edetic Acid
Gallium Radioisotopes*
Humans
Ligands
Male
Pilot Projects
Positron Emission Tomography Computed Tomography / methods
Prostate / pathology
Prostate-Specific Antigen
Prostatic Neoplasms* / diagnostic imaging
Prostatic Neoplasms* / pathology
Tissue Distribution

Substances

gallium 68 PSMA-11
Gallium Radioisotopes
Ligands
Prostate-Specific Antigen
Edetic Acid