Treatment starts in trial of theranostic for 177Lu-PSMA-617–ineligible mCRPC

The first patient has been treated in the phase 1/2 COMBAT study (NCT05633160) examining the novel theranostic ⁶⁴Cu/⁶⁷Cu-SAR-Bombesin (BBN) in patients with gastrin releasing peptide receptor (GRPr)-expressing metastatic castration-resistant prostate cancer (mCRPC) who are ineligible for 177Lu-PSMA-617 (lutetium Lu 177 vipivotide tetraxetan; Pluvicto).¹

Pending safety results, study investigators aim to explore doses of up to 14 GBq of 67Cu SAR-Bombesin over a maximum of 4 cycles.The estimated study completion date for the COMBAT trial is May 2026.

The pan-cancer radiopharmaceutical SAR-Bombesin targets GRPr, which is found on tumor cells in several cancers. According to Clarity Pharmaceuticals, the company developing the treatment, GRPr is present in most prostate tumors, including those that test negative for PSMA.¹

The theranostic ⁶⁴Cu/⁶⁷Cu-SAR-BBN combines the imaging product ⁶⁴Cu-SAR-BBN and the targeted therapy ⁶⁷Cu-SAR-BBN. In the open-label, single-arm, dose-escalation/expansion COMBAT trial, ⁶⁴Cu-SAR-BBN will be used for the selection of appropriate patients to receive treatment with ⁶⁷Cu-SAR-BBN.¹

"SAR-Bombesin has already resulted in improvements to the management of prostate cancer for patients with PSMA-negative or low PSMA expressing lesions through diagnostic trials and we hope to confirm its safety and efficacy in this theranostic trial. We look forward to progressing the COMBAT trial and building on the compelling data from our preclinical and clinical studies to date. Combined with the logistical and manufacturing benefits of Targeted Copper Theranostics and with commercial quantities of the ⁶⁷Cu radioisotope now being routinely produced domestically in the US, we see a clear path to bringing SAR-Bombesin and SAR-bisPSMA to the prostate cancer patient population in need of novel treatments," Dr Alan Taylor, executive chairman, Clarity, stated in a press release.¹

The COMBAT study aims to enroll up to 38 patients at clinical locations in the United States. To enroll on the trial, patients must have mCRPC, an ECOG performance status of 0 to 2, and a castrate level of serum/plasma testosterone (<50 ng/dL or <1.7 nmol/L). Individuals with symptomatic brain metastases are not eligible to enroll.²

Pending safety results, study investigators aim to explore doses of up to 14 GBq of ⁶⁷Cu SAR-Bombesin over a maximum of 4 cycles.The estimated study completion date for the COMBAT trial is May 2026.²

177Lu-PSMA-617 is approved for the treatment of patients with PSMA-positive mCRPC who have been treated with androgen receptor pathway inhibition and taxane-based chemotherapy. The agent was approved in 2022 based on findings from the VISION trial.³

References

1. First patient treated with Cu-67 SAR-Bombesin in theranostic prostate cancer trial. Published online October 3, 2023. Accessed October 3, 2023. https://www.prnewswire.com/news-releases/first-patient-treated-with-cu-67-sar-bombesin-in-theranostic-prostate-cancer-trial-301945053.html

2. NIH US National Library of Medicine ClinicalTrials.gov. 64Cu-SAR-BBN and 67CU SAR-BBN for Identification and Treatment of Gastrin Releasing Peptide Receptor (GRPR)-Expressing Metastatic Castrate Resistant Prostate Cancer in Patients Who Are Ineligible for Therapy With 177Lu-PSMA-617 (COMBAT). Last updated June 18, 2023. Accessed June 19, 2023. https://clinicaltrials.gov/ct2/show/NCT05633160

3. US Food & Drug Administration. FDA approves Pluvicto for metastatic castration-resistant prostate cancer. Published online March 23, 2022. Accessed June 19, 2023. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-pluvicto-metastatic-castration-resistant-prostate-cancer