Novel therapeutics for prostate cancer visualized with SPECT/CT

Prostate cancer (PCa) is the most common cancer in men worldwide with frequent reoccurrence of the disease, despite improvements in treatment. Therapy with monoclonal antibodies, conjugated to cytotoxic drugs, has achieved great attention in the past decade, especially those targeting the prostate-specific membrane antigen (PSMA) which is overexpressed in the majority of PCa patients. Several anti-PSMA-based drug conjugates have been characterized so far, reporting anti-tumor efficacy in vivo. Most of these drugs however, apply random conjugation chemistry to the antibody leading to variable pharmacophysical properties.

The present study demonstrates the characterization of four novel site-specifically anti-PSMA drug conjugates labeled with ¹¹¹In imaged in high-resolution using the U-SPECT/CT scanner (MILabs, Utrecht, the Netherlands). All ¹¹¹In-labeled conjugates presented high uptake in PSMA-positive tumors and low uptake in healthy tissue (Figure 1). Mice that were treated with these compounds showed higher median survival than PBS-treated control groups, suggesting a future potential of these compounds in PCa theranostics.

Read more in J Nucl Med

Summary:

• U-SPECT/CT was used to visualize novel ¹¹¹In-anti-PSMA drug conjugates in PSMA positive tumors.
• High-contrast visualization was achieved offering new possibilities for tumor imaging.
• Inhibition of tumor growth and higher median survival was achieved with the new drug conjugates.

Figure 1: Representative SPECT/CT images of PSMA-positive xenografts injected with two of the ¹¹¹In-labeled-anti-PSMA drug conjugates.