New PET Agent Rapidly and Accurately Visualizes Lesions in Clear Cell Renal Cell Carcinoma Patients

Clear cell renal cell cancer (ccRCC) represents 70-80% of renal cell carcinoma cases. While localized disease can be effectively treated with surgery and ablative therapies, one-third of patients either present with or develop metastatic disease, which has a poor prognosis. Despite significant advancements in treatment for renal cell carcinoma, the five-year survival rate for those with distant metastatic disease remains disappointingly low. Now, new research has found that a novel investigational PET imaging agent is capable of quickly and accurately visualizing lesions in ccRCC patients.

The carbonic anhydrase IX (CAIX) encoding gene is overexpressed in over 90% of ccRCC cases and is limited to gastrointestinal tissue, which provides both diagnostic and therapeutic potential. The ongoing first-in-human GaLuCi study by researchers at the Peter MacCallum Cancer Centre (Melbourne, Australia), focuses on evaluating the safety, tolerability, and imaging efficacy of the CAIX-targeted imaging agent, [68Ga]Ga-DPI-4452 (Debio 0328). This study involved three patients with histologically confirmed unresectable locally advanced or metastatic ccRCC, who have undergone at least two treatment lines in a metastatic setting. These patients were administered Debio 0328 and then underwent whole-body PET/CT scans at intervals of 15 minutes, and one, two, and four hours post-administration. The initial imaging results, pharmacokinetics, and safety data from these patients were thoroughly analyzed.

Image: Whole-body maximum-intensity projections over time after [68Ga]Ga-DPI-4452 administration (Photo courtesy of SNMMI)

The findings indicate that Debio 0328 outperforms standard CT imaging for ccRCC. This agent not only provides significantly quicker imaging results but may also be used in the future as part of a theranostic pair. Debio 0328 demonstrated exceptional imaging capabilities right from the first time point, with sustained tumor uptake observed up to four hours after administration. The imaging agent was quickly cleared from the blood and urine, and no clinically significant toxicity was observed in the patients. Furthermore, Debio 0328 exhibited an extremely high tumor-to-background ratio, making the surrounding tissues almost invisible, except for gastrointestinal uptake. The optimal time point for lesion assessment using this agent was one hour post-administration, significantly reducing the time compared to the three to seven days required for previous PET imaging studies that used antibody-based methods.

“Further work is now needed to assess whether this new imaging test could improve patient diagnosis, management, and outcomes,” said Professor Michael Hofman MBBS, FRACP, FAANMS, nuclear medicine specialist at the Peter MacCallum Cancer Centre. “These findings are also encouraging for the evaluation of 177Lu-DPI-4452 (Debio 0228) as a treatment for ccRCC, which will be examined in the second arm of GaLuCi study.”

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Peter MacCallum Cancer Centre