On January 24, 2025 Clarity Pharmaceuticals (ASX: CU6) ("Clarity" or "Company"), a clinical-stage radiopharmaceutical company with a mission to develop next-generation products that improve treatment outcomes for children and adults with cancer, reported that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation (FTD) for 64Cu-SAR-bisPSMA for positron emission tomography (PET) imaging of prostate-specific membrane antigen (PSMA) positive prostate cancer lesions in patients with biochemical recurrence (BCR) of prostate cancer following definitive therapy (Press release, Clarity Pharmaceuticals, JAN 24, 2025, View Source [SID1234649847]).
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This milestone builds on Clarity’s earlier receipt of an FTD for 64Cu-SAR-bisPSMA in patients with suspected metastasis of prostate cancer who are candidates for initial definitive therapy1. These 2 FTDs enable the Company to accelerate the development of its comprehensive diagnostic program with this product.
The FDA’s FTD is designed to expedite the development and regulatory review of novel drugs addressing serious conditions with significant unmet medical needs. For 64Cu-SAR-bisPSMA, it provides a number of product development advantages. The designation paves the way for a faster review process once Clarity submits its product approval applications. Additionally, it enables more frequent communication with the FDA, allowing for rapid resolution of queries during development. Furthermore, Clarity can submit completed sections of its application as they are ready, rather than waiting for the entire package to be finished before it can be lodged with the FDA. These benefits would reduce the review time needed to bring this innovative prostate cancer imaging agent to market, potentially improving diagnosis and treatment planning for patients sooner.
The FTD submission highlighted several advantages of 64Cu-SAR-bisPSMA over currently approved PSMA PET agents due to the bivalent structure of bisPSMA and the longer half-life of 64Cu (12.7 hours vs. <2 hours for 18F and 68Ga). These advantages include improved diagnostic performance, flexible imaging schedule and broader availability. The data for this FTD submission was primarily focused on the results of the Phase I/II COBRA study, which assessed the safety and diagnostic performance of 64Cu-SAR-bisPSMA in detecting prostate cancer in patients with BCR of their disease who had a negative or equivocal standard of care (SOC) scan at study entry. Advantages have been shown with same-day and next-day imaging, however, the standout was next-day 64Cu-SAR-bisPSMA PET imaging, showing localised disease in up to 80% of participants and detecting lesions as small as 2 mm. This compares favourably against the current SOC PSMA PET agents, with which the detection of lesions smaller than 5 mm is challenging. The number of lesions detected by 64Cu-SAR-bisPSMA on next-day imaging almost doubled compared to same-day imaging, and 64Cu-SAR-bisPSMA was also able to identify more lesions at much earlier timepoints (Figure 1) compared to approved PSMA PET agents.The COBRA trial paved the way for Clarity’s second diagnostic registrational trial, AMPLIFY, and an investigator-initiated trial (IIT) Co-PSMA, led by Prof Louise Emmett at St Vincent’s Hospital Sydney. The AMPLIFY trial will be a non-randomised, single-arm, open-label, multi-centre, Phase III diagnostic clinical trial of 64Cu-SAR-bisPSMA PET in approximately 220 participants with rising or detectable PSA after initial definitive treatment. As a pivotal trial, the final study results are intended to provide sufficient evidence to support an application to the FDA for approval of 64Cu-SAR-bisPSMA as a new diagnostic imaging agent in prostate cancer in patients with BCR. The Co-PSMA IIT will aim to build on the evidence generated so far, evaluating the diagnostic performance of 64Cu-SAR-bisPSMA in comparison to SOC 68Ga-PSMA-11 for the detection of recurrent prostate cancer lesions with curative intent.
Clarity’s Executive Chairperson, Dr Alan Taylor, commented, "Receiving the second FTD for 64Cu-SAR-bisPSMA and well within the 60-day period following our application submission, reserved by the U.S. FDA for review, is yet another significant milestone in our bisPSMA program. This highlights the high unmet need for novel diagnostics in prostate cancer and the high quality of data we presented to the FDA.
"The market for first-generation diagnostic PSMA PET today is approximately US$2 billion (AU$3.2 billion) in the U.S. alone, with little differentiation between products. It is expected to further grow to US$3 billion (AU$4.75 billion) by 2029. The development pipeline of new products coming to market, outside of 64Cu-SAR-bisPSMA, also offers no differentiation from the existing offering, with some new entrants commercialising the unpatented 68Ga-PSMA-11 agent, which has been capitalised on by three separate groups already.
"Being able to now fast-track the development of 64Cu-SAR-bisPSMA for patients with BCR as well as for patients prior to initial definitive therapy is incredibly exciting. The news is especially timely as we are actively preparing to commence recruitment for our second registrational trial, AMPLIFY, in the coming months. The designation will allow us to work closely with the FDA to facilitate the development process and accelerate the approval of what could become a best-in-class diagnostic.
"The dual targeting structure of bisPSMA enables increased uptake and retention of the product in the lesions, while the longer half-life of copper-64 provides greater flexibility with imaging scheduling, including next-day imaging (something that gallium-68 and fluorine-18 based products cannot support). When combined, these features make 64Cu-SAR-bisPSMA stand out from its competitors who are known to have issues with sensitivity. We have seen 2-3 times higher uptake in prostate cancer lesions and the identification of more lesions using 64Cu-SAR-bisPSMA compared to 68Ga-PSMA-11 in pre-prostatectomy patients in our PROPELLER study. The COBRA trial results showed great diagnostic performance in the BCR setting, with lesions identified by 64Cu-SAR-bisPSMA in the 2-mm range and visualised many months before SOC PSMA PET agents are able detect them.
"Not only are we developing a product that may have improved diagnostic performance compared to SOC PSMA PET agents, but the longer half-life of copper-64 also enables a longer shelf-life of 64Cu-SAR-bisPSMA than currently used diagnostic radiopharmaceuticals, allowing for centralised manufacture and wider distribution. These attributes have the potential to reduce disparities in prostate cancer care and ensure that most patients, regardless of geographic location, can benefit from the latest advances in diagnostic technology.
"This designation highlights the unique opportunity for 64Cu-SAR-bisPSMA in this very large market by addressing the limitations of the current-generation diagnostic radiopharmaceuticals and providing patients with prostate cancer with a more accurate diagnosis leading to more optimal treatment options. As such, we are fully committed to advancing the development of this best-in-class product to address the critical need for more accurate and accessible diagnostic tools in prostate cancer management."
About SAR-bisPSMA
SAR-bisPSMA derives its name from the word "bis", which reflects a novel approach of connecting two PSMA-targeting agents to 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-bisPSMA 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 in men worldwide4. Prostate cancer is the second-leading causes of cancer death in American men. The American Cancer Institute estimates in 2025 there will be about 313,780 new cases of prostate cancer in the U.S. and around 35,770 deaths from the disease.