AUA 2022: Results of the Phase 1 Safety and Efficacy Prostate Specific Membrane Antigen (PSMA) Targeting Fluorophore for Image Guided Surgery in Patients Undergoing Robotic Prostatectomy

(UroToday.com) The 2022 Annual Meeting of the American Urological Association was host to a podium session of surgical therapies in localized prostate cancer. Dr. Hao Gia Nguyen presented the results of his group’s Phase 1 trial evaluating the safety and efficacy of PSMA targeting fluorophore for image-guided surgery in patients undergoing robotic prostatectomy.

 Dr. Nguyen began the presentation by highlighting that in high-risk prostate cancer patients, 15-40% of radical prostatectomy procedures result in positive margins or missed metastatic disease in lymph nodes. PSMA is a glycoprotein found on the cell surface of prostatic cells and is overexpressed on prostate cancer tissue by 100-1000 fold with low expression in native prostate and healthy tissues. ~90% of prostate tumors express PSMA.

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IS-002 is a PSMA targeting fluorescent dye that is injected intravenously and is firefly compatible. It allows for fluorescent due to be detected in real-time intra-operatively. This agent has been tested in pre-clinical animal models and shown to be safe and have value in the detection of residual disease.

 

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The authors hypothesized that IS-002 fluorescence-guided surgery on the da Vinci Surgical System may improve oncological outcomes through precision tumor excision.

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This agent has proven to be safe with only Grade 1 adverse events reported so far (24 green urine, 1 green feces, and 1 green discoloration at injection site). There were no clinically significant CBC, CMP, urinalysis, or 12-lead ECG changes.

IS-002 allowed for a strong fluorescent signal from the primary tumor, residual disease, and involved lymph nodes. 

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Pathologic analysis confirmed that IS-002 targets prostate cancer cells.

 

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With regards to the exploratory efficacy endpoints, IS-002 allowed for detection of locoregional tissue invasion in 6/24 patients, residual disease in the resection bed in 5/24 patients, and tumor positive lymph nodes in 3/24.

The authors concluded: IS-002 is safe and well-tolerated, enabling enhanced intraoperative tumor detection. Based on the very encouraging results of this phase 1 study, a randomized phase 2 study is planned. Currently planning for a Phase 2 multicenter trial involving UCSF, MSKCC, JHU, and Mayo Clinic is underway with a primary objective of efficacy and a secondary objective of safety.

 

Presented By: Hao Gia Nguyen, Associate Professor, Urologic Oncology, UCSF, San Fransisco, CA

Written By: Rashid Sayyid, MD, MSc – Urology Chief Resident, Augusta University/Medical College of Georgia, @rksayyid on Twitter during the 2022 Annual Meeting of the American Urological Association, New Orleans, LA, May 13 – 16, 2022