Impact of Tumor Burden on Normal Organ Distribution in Patients Imaged with CXCR4-Targeted [68Ga]Ga-PentixaFor PET/CT
Sebastian E. Serfling, Constantin Lapa, Niklas Dreher, Philipp E. Hartrampf, Steven P. Rowe, Takahiro Higuchi, Andreas Schirbel, Alexander Weich, Stefanie Hahner, Martin Faßnacht, Andreas K. Buck, Rudolf A. Werner
Abstract
Abstract Background CXCR4-directed positron emission tomography/computed tomography (PET/CT) has been used as a diagnostic tool in patients with solid tumors. We aimed to determine a potential correlation between tumor burden and radiotracer accumulation in normal organs. Methods Ninety patients with histologically proven solid cancers underwent CXCR4-targeted [ 68 Ga]Ga-PentixaFor PET/CT. Volumes of interest (VOIs) were placed in normal organs (heart, liver, spleen, bone marrow, and kidneys) and tumor lesions. Mean standardized uptake values (SUV mean ) for normal organs were determined. For CXCR4-positive tumor burden, maximum SUV (SUV max ), tumor volume (TV), and fractional tumor activity (FTA, defined as SUV mean x TV), were calculated. We used a Spearman's rank correlation coefficient (ρ) to derive correlative indices between normal organ uptake and tumor burden. Results Median SUV mean in unaffected organs was 5.2 for the spleen (range, 2.44 – 10.55), 3.27 for the kidneys (range, 1.52 – 17.4), followed by bone marrow (1.76, range, 0.84 – 3.98), heart (1.66, range, 0.88 – 2.89), and liver (1.28, range, 0.73 – 2.45). No significant correlation between SUV max in tumor lesions (ρ ≤ 0.189, P ≥ 0.07), TV (ρ ≥ -0.204, P ≥ 0.06) or FTA (ρ ≥ -0.142, P ≥ 0.18) with the investigated organs was found. Conclusions In patients with solid tumors imaged with [ 68 Ga]Ga-PentixaFor PET/CT, no relevant tumor sink effect was noted. This observation may be of relevance for therapies with radioactive and non-radioactive CXCR4-directed drugs, as with increasing tumor burden, the dose to normal organs may remain unchanged.