First participants imaged in SAR-Bombesin prostate cancer trial in Australia

Sydney, Australia 14 September 2022

Highlights

• First participants were recruited and imaged in the diagnostic investigator-initiated trial (IIT) led by Prof Louise Emmett at St Vincent’s Hospital Sydney with one of Clarity’s core products, SAR-Bombesin
• The Phase II IIT builds on the data generated in PSMA-negative prostate cancer patients imaged at St Vincent’s Hospital under the Therapeutic Goods Administration (TGA) Special Access Scheme (SAS) as well as from the pilot diagnostic IIT investigating SAR-Bombesin in breast cancer patients (C-BOBCAT)
• A significant proportion of prostate cancer patients express the target for SAR-Bombesin, and approximately 20% of prostate cancer patients with biochemical recurrence (BCR) are PSMA-PET negative. These patients are therefore unsuitable for the currently approved PSMA targeting agents, presenting an opportunity to target these cancers with Clarity’s SAR-Bombesin product

Clarity Pharmaceuticals (ASX: CU6) (“Clarity”), a clinical stage radiopharmaceutical company with a mission to develop next-generation products that improve treatment outcomes for children and adults with cancer, is pleased to announce that it has successfully imaged its first participants in the diagnostic ⁶⁴Cu SAR-Bombesin trial (BOP) for patients with PSMA-negative prostate cancer in Australia.

BOP (Copper-64 SAR Bombesin in Prostate Specific Membrane Antigen (PSMA) negative Prostate Cancer) is a Phase II investigator-initiated trial (IIT) in up to 30 patients led by Prof Louise Emmett at St Vincent’s Hospital, Sydney. The BOP trial is assessing the safety of ⁶⁴Cu-SAR-Bombesin as well as looking at the diagnostic potential across two different groups of men:

1. Participants with suspected biochemical recurrence (BCR) of their prostate cancer who have negative PSMA positron emission tomography (PET) imaging scans or low PSMA expression disease.
2. Participants with metastatic castrate resistant prostate cancer (mCRPC) who are not eligible for PSMA therapy.

The trial is imaging with ⁶⁴Cu SAR-Bombesin on the day of administration as well as at later timepoints.

Prof Louise Emmett (St Vincent’s Hospital Sydney), Principal Investigator in the BOP trial, commented, “We are very pleased to have recruited and imaged the first participants in this study. The SAR-Bombesin product is a promising target for a large patient population with a high unmet need and few treatments available to them. We are excited to now make the product available to a larger pool of patients under clinical trial conditions”.

“SAR-Bombesin has already shown very promising data to date through a SAS case study¹, demonstrating diagnostic imaging potential in PSMA-negative prostate cancer and highlighting potential utility of the product as a theranostic agent. We are now looking forward to further investigating the role of SAR-Bombesin in the better management of patients,” said Prof Emmett.

Clarity’s Executive Chairman, Dr Alan Taylor, commented, “The commencement of this trial is yet another step forward in our collaboration with Prof Emmett and St Vincent Hospital Sydney as the BOP IIT is now our third clinical trial conducted in partnership. We are pleased that this collaboration has already resulted in changes in the management of the disease for patients in our own city of Sydney, as we head towards our ultimate goal of improving treatment outcomes for children and adults with cancer around the world.”

“We believe that SAR-Bombesin has potential to provide large patient populations with accurate and precise detection and treatment of cancers that express the target and deliver clinical, environmental and logistical benefits enabled by the copper isotope pairing,” said Dr Taylor.

Clarity’s Prostate Cancer clinical trial program overview

About SAR-Bombesin

SAR-Bombesin is a highly targeted pan-cancer radiopharmaceutical with broad cancer application. It targets the gastrin-releasing peptide receptor (GRPr) present on cells of a range of cancers, including but not limited to prostate, breast and ovarian cancers. GRPr is found in approximately 75-100% of prostate cancers, including prostate cancers that don’t express PSMA (PSMA-negative)^2-6. The product utilises Clarity’s proprietary sarcophagine (SAR) technology that securely holds copper isotopes inside a cage-like structure, called a chelator. Unlike other commercially available chelators, the SAR technology prevents copper leakage into the body. SAR-Bombesin is a Targeted Copper Theranostic (TCT) that can be used with isotopes of copper-64 (Cu-64 or ⁶⁴Cu) for imaging and copper-67 (Cu-67 or ⁶⁷Cu) for therapy.

About Prostate Cancer

Prostate cancer is the second most common cancer diagnosed in men globally and the fifth leading cause of cancer death worldwide⁷. The National Cancer Institute estimates in 2022 there will be 268,490 new cases of prostate cancer in the US and around 34,500 deaths from the disease⁸.

Approximately 20% of prostate cancers with BCR are PSMA-PET negative^9-12. These patients are therefore unlikely to respond to therapeutic PSMA-targeted products and currently have few treatment options available to them. Given the prostate cancer indication is one of the largest in oncology, there is a significant unmet medical need in this segment. The SAR-Bombesin 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.

About Clarity

Clarity is a clinical stage radiopharmaceutical company focused on the treatment of serious disease. The Company is a leader in innovative radiopharmaceuticals, developing targeted copper theranostics based on its SAR Technology Platform for the treatment of cancer in children and adults.

www.claritypharmaceuticals.com

References

1. Niketh J, Bao H, Emmett, L. 64Cu-SAR-Bombesin PET-CT for the detection of biochemically recurrent PSMA-PET negative prostate cancer: a case series. 2022 ANZUP Annual Scientific Meeting. Program of Abstracts. Vol 18. Issue S1. P55. <https://doi.org/10.1111/ajco.13827>
2. Markwalder R, Reubi JC. Gastrin-releasing peptide receptors in the human prostate: relation to neoplastic transformation. Cancer research. 1999;59(5):1152-1159.
3. Fleischmann A, Waser B, Reubi JC. High expression of gastrin-releasing peptide receptors in the vascular bed of urinary tract cancers: promising candidates for vascular targeting applications. Endocrine-related cancer. 2009;16(2):623-633.
4. Ananias HJ, van den Heuvel MC, Helfrich W, de Jong IJ. Expression of the gastrin-releasing peptide receptor, the prostate stem cell antigen and the prostate-specific membrane antigen in lymph node and bone metastases of prostate cancer. The Prostate. 2009;69(10):1101-1108.
5. Reubi JC, Wenger S, Schmuckli-Maurer J, Schaer JC, Gugger M. Bombesin receptor subtypes in human cancers: detection with the universal radioligand (125)I-[D-TYR(6), beta-ALA(11), PHE(13), NLE(14)] bombesin(6-14). Clin Cancer Res. 2002;8(4):1139-1146.
6. Sun B, Halmos G, Schally AV, Wang X, Martinez M. Presence of receptors for bombesin/gastrin-releasing peptide and mRNA for three receptor subtypes in human prostate cancers. The Prostate. 2000;42(4):295-303.
7. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries <https://acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.21660>
8. American Cancer Society, Cancer Statistics Center, <https://cancerstatisticscenter.cancer.org/?_ga=2.79808020.284532473.1620009137-1916069442.1615761164#!/cancer-site/Prostate>
9. Afshar-Oromieh A, Holland-Letz T, Giesel FL, et al. Diagnostic performance of ⁶⁸Ga-PSMA-11 (HBED-CC) PET/CT in patients with recurrent prostate cancer: evaluation in 1007 patients. Eur J Nucl Med Mol Imaging. 2017 Aug;44(8):1258-1268.
10. Ferraro DA, Rüschoff JH, Muehlematter UJ, et al. Immunohistochemical PSMA expression patterns of primary prostate cancer tissue are associated with the detection rate of biochemical recurrence with ⁶⁸Ga-PSMA-11-PET. Theranostics. 2020;10(14):6082-6094.
11. Baratto L, Song H, Duan H, et al. PSMA- and GRPR-Targeted PET: Results from 50 Patients with Biochemically Recurrent Prostate Cancer. J Nucl Med. 2021;62(11):1545-1549.
12. Mapelli P, Ghezzo S, Samanes Gajate AM, et al. ⁶⁸Ga-PSMA and ⁶⁸Ga-DOTA-RM2 PET/MRI in Recurrent Prostate Cancer: Diagnostic Performance and Association with Clinical and Histopathological Data. Cancers (Basel). 2022;14(2):334.

Media Contact

Clarity Pharmaceuticals

Dr Alan Taylor
Executive Chairman
+61 (0)413 871 165
ataylor@claritypharm.com

Citadel-MAGNUS

Catherine Strong
Investor/Media Relations
+61 (0)406 759 268
cstrong@citadelmagnus.com

This announcement has been authorised for release by the Executive Chairman.