Novel imaging agent explored in patients with PSMA-negative prostate cancer

The first patient has been successfully imaged in the phase 2 SABRE trial, which is exploring the novel PET-imaging agent ⁶⁴Cu SAR-Bombesin in patients with PSMA-negative biochemically recurrent prostate cancer.¹

Clarity Pharmaceuticals, the developer of ⁶⁴Cu SAR-Bombesin, explained in a press release that the impetus for launching the trial was to address the unmet need faced by the approximately 20% of patients with biochemically recurrent prostate cancer who are PSMA-PET negative.² These patients are unable to respond to the burgeoning class of PSMA-targeted products and thus are left with few available treatment options.

The target of ⁶⁴Cu SAR-Bombesin is the Gastrin Releasing Peptide receptor (GRPr), which is found on prostate tumors as well as several other tumors. “As such, the product could offer valuable imaging and therapeutic options for not only PSMA-negative patients, but also the large number of patients that have the target receptor on their cancers,” Clarity noted in a press release.

Overall, the multicenter, single-arm, non-randomized, open-label SABRE trial (NCT05407311), aims to enroll up to 50 patients with PSMA-negative biochemically recurrent prostate cancer (known or suspected) following definitive therapy (eg, surgery or radiation). Safety and tolerability of ⁶⁴Cu SAR-Bombesin, as well as its effectiveness in accurately detecting prostate recurrence, are the primary outcome measures of the study.

Positive initial safety and efficacy data for ⁶⁴Cu SAR-Bombesin were shown in a pilot trial of the imaging agent in patients with breast cancer. Results from this trial were shared in an abstract presented at the 2022 ASCO Annual Meeting.³

"We are very excited to have recruited and imaged the first participant in this trial which will explore the clinical benefits of the novel SAR-Bombesin agent. Based on the promising preclinical and clinical data to date, SAR-Bombesin shows great potential for improving the diagnosis and treatment for not only patients with prostate cancer that are PSMA negative, but also across broader prostate cancer indications,” Luke Nordquist, MD, CEO, Urologic Medical Oncologist and principal investigator at the Urology Cancer Center and GU Research Network (GURN) in Omaha, Nebraska, stated in a press release.¹

"SABRE is the third trial with Clarity's Targeted Copper Theranostics (TCTs) that GURN is recruiting into. This momentum is underpinned by our belief that the TCTs are the next-generation products that will enable the radiopharmaceutical field to overcome the manufacturing and supply chain challenges associated with the current products in the market and facilitate the expansion of radiopharmaceuticals into the large global oncology market. We look forward to generating data from the trial to validate the potential clinical benefits for large patient populations and improve patient care."

References

1. First participant imaged in Phase II SAR-Bombesin prostate cancer trial in the US. Published online and accessed October 6, 2022. https://prn.to/3SLxelN

2. IND approval from the US FDA for Phase II SAR-Bombesin imaging trial in prostate cancer. Published online June 6, 2022. Accessed June 9, 2022. https://prn.to/3NCLISI

3. Wong K, Sheehan-Dare G, Nguyen A, et al. 64Cu-SAR-Bombesin PET-CT imaging in the staging of ER+/PR+/HER2- metastatic breast cancer: Safety, dosimetry, and feasibility in a phase I trial. J Clin Oncol 40, no. 16_suppl (June 01, 2022) 3092-3092. doi: 10.1200/JCO.2022.40.16_suppl.3092