The novel investigational positron-emission tomography (PET) imaging agent gallium (Ga)-68–DPI-4452 may offer rapid and accurate visualization of lesions in patients with clear cell renal cell carcinoma, according to a recent study published by Hofman et al in The Journal of Nuclear Medicine. The findings suggested that Ga-68–DPI-4452 may be superior to standard computed tomography (CT) imaging in this cancer subtype.
Background
Clear cell renal cell carcinoma accounts for 70% to 80% of renal cell carcinoma cases. Although localized disease may be cured with surgery and ablative therapy regimens, one-third of patients present with or develop metastases and have poor prognosis. Despite major advances in the treatment of renal cell carcinoma, the 5-year relative survival rate for distant metastatic disease remains low.
“The carbonic anhydrase IX (CAIX) encoding gene is overexpressed in more than 90% of [clear cell renal cell carcinoma] cases and is restricted to gastrointestinal tissue, presenting both diagnostic and therapeutic opportunities” explained lead study author Michael Hofman, MBBS, FRACP, FAANMS, a nuclear medicine specialist at the Peter MacCallum Cancer Centre in Melbourne, Australia. “In this study, we aim to assess the safety, tolerability, and imaging characteristics of the CAIX-targeting imaging agent Ga-68–DPI-4452,” he added.
Study Methods and Results
In the recent GaLuCi study, researchers assigned three patients with histologically confirmed unresectable locally advanced or metastatic clear cell renal cell carcinoma—who received at least two lines of treatment in a metastatic setting—to receive Ga-68–DPI-4452 and undergo whole-body PET/CT imaging at 15 minutes as well as 1, 2, and 4 hours following administration. They then assessed the pharmacokinetics and safety data of the patients.
The researchers found that Ga-68–DPI-4452 offered significant imaging beginning at 15 minutes—with sustained tumor uptake up to 4 hours after administration. The agent was rapidly eliminated from the blood and urine, and the researchers reported no clinically significant toxicity.
Conclusions
The researchers highlighted that Ga-68–DPI-4452 may allow for significantly faster imaging and could be utilized as a part of a theranostic pair in the future.
“Ga-68–DPI-4452 PET/CT revealed an exceptionally high tumor-to-background ratio, with background tissues nearly invisible with the exception of gastrointestinal uptake. One hour after administration was deemed the optimal time point for lesion assessment, which is substantially shorter than the 3 to 7 days needed in previous PET imaging studies using antibody approaches,” emphasized Dr. Hofman. “Further work is now needed to assess whether this new imaging test could improve patient diagnosis, management, and outcomes. These findings are also encouraging for the evaluation of lutetium-177–DPI-4452 as a treatment for [clear cell renal cell carcinoma], which will be examined in the second arm of GaLuCi study,” he concluded.
Disclosure: For full disclosures of the study authors, visit jnm.snmjournals.org.
