SNMMI 2017: Preclinical Targeted Photodynamic Therapy Shown Highly Effective Against Prostate Cancer
Researchers presented a preclinical study at the 2017 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) that demonstrated the efficacy and optimal dose for targeted photodynamic therapy (PDT) to treat prostate cancer before and during surgery (Abstract 7).
Targeted Photodynamic Therapy
Prostate-specific membrane antigen (PSMA) was targeted with an anti–PSMA antibody radiolabeled with the tracer indium-111 (In-111) and coupled with specialized photosensitizers that cause cell destruction upon exposure to near-infrared radiation. The combined formula is In-111 DTPA-D2B-IRDye700DX.
“Coupling the photosensitizer to an imaging agent that targets PSMA on the tumor surface makes it possible to selectively and effectively destroy prostate tumor remnants and micrometastases, while surrounding healthy tissues remain unaffected,” said Susanne Lütje, MD, PhD, lead author of the study from the Department of Radiology and Nuclear Medicine at Radboud University Medical Center in Nijmegen, the Netherlands, and the Clinic for Nuclear Medicine at University Hospital Essen, Germany.
This technique optimizes prostate cancer care by allowing visualization of tumors prior to surgery, providing real-time guidance to surgeons in the operating room, and priming tumors for photodynamic therapy when surgery isn’t enough or risks damage to sensitive structures.
A gamma probe is used to detect PSMA-expressing tumor cells. Photosensitizers can then be activated with light in the near-infrared wavelength, which causes them to emit fluorescence, or oxygen radicals, that damage PSMA-overexpressing tumor tissues.
Major Findings
Study results showed effective localization of the drug at the site of tumors, as well as effective imaging and photodynamic therapy via near-infrared exposure in mice. Further study in humans is needed before this procedure could be made available for prostate cancer patients.
“In the future, this novel approach to prostate cancer could significantly improve the effectiveness of treatment, reduce recurrent disease, and, ultimately, prolong survival and protect quality of life for patients,” said Dr. Lütje.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
