MedicalResearch.com Interview with:
Dr. Susanne Lütje
Universitätsklinikum Essen (AöR)
Klinik für Nuklearmedizin
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Prostate cancer (PCa) is the most common cancer in men and accounts for a significant amount of morbidity and mortality. At present, the curative treatment option of choice for localized stages of PCa is radical prostatectomy, which may include extended lymph node dissection. Unfortunately, surgical procedures can be accompanied by complications such as urinary incontinence. Most importantly, small tumor deposits may not be seen by the surgeon during surgery and could ultimately lead to disease recurrence. To overcome these issues, new and innovative treatments are needed. The prostate-specific membrane antigen (PSMA) is a surface protein that is overexpressed in prostate cancer and can be used as a target to guide new therapies.
Photodynamic therapy (PDT) is an ablative procedure in which tumor cells can be destroyed effectively by irradiation of light of a specific wavelength, which activates previously administered photosensitizers. The photosensitizers can respond by emitting fluorescence or emitting oxygen radicals which can cause cellular damage. Coupling the photosensitizer to an agent that targets PSMA on the tumor surface offers the possibility to selectively and effectively destroy prostate tumor remnants and micrometastases, while surrounding healthy tissues remain unaffected.
In our study, the PSMA targeting antibody D2B was coupled to the photosensitizer IRDye700DX and radiolabeled with 111In. In a mouse model, this multi-modality agent was used to preoperatively visualize tumor lesions with SPECT/CT to allow rough localization of the tumors. During surgery, the fluorescent signal originating from the photosensitizer facilitates visualization of tumors and residual tumor tissue, so the surgeon can be guided towards accurate resection of the entire tumors and metastases. In addition, the PSMA-targeted PDT can be applied to destroy small tumor deposits in cases where close proximity of the tumors.