with Disseminated Gastroenteropancreatic Neuroendocrine Tumors: The Value of Measuring Absorbed Dose to the Kidney

TLDR: In this paper, Lu-Octreotate (8 GBq) was given one to five times (median = 3) with a 6-week interval between each.

Abstract: Background Peptide receptor radiation therapy (PRRT) using [ 177 Lu-DOTA 0 -Tyr 3 ]-octreotate is a new, promising option for treatment of disseminated gastroenteropancreatic neuroendocrine tumors (GEPNETs). Methods During 2006-2008, 26 patients with disseminated GEPNETs were treated with 177 Lu-octreotate. Radiologic response (RECIST), biochemical response [plasma chromogranin-A (P-CgA)], hematologic toxicity [Common Toxicity Criteria (CTC)], absorbed dose to the kidneys (conjugate view method), and glomerular filtration rate (GFR) were analyzed. Results 177 Lu-octreotate (8 GBq) was given one to five times (median = 3) with a 6-week interval between each. Sixteen of the 26 patients were evaluated radiologically; 6 (38%) had partial response (PR), 8 (50%) had stable disease (SD), and 2 (13%) had progressive disease (PD). Seventeen of the 26 patients were evaluated biochemically; 6 (35%) showed a C30% decrease, 8 (47%) showed a C20% increase, and 3 (18%) showed neither a C30% decrease nor a C20% increase. The mean absorbed dose to the kidneys was 24 Gy. With a dose limit of 27 Gy to the kidneys, 10 patients did not receive the planned four treatments, while four patients had the potential to receive additional treatment. A significant reduction (p = 0.0013) of GFR was observed at follow-up. Three patients experienced CTC grade 3 hematologic toxicity. Conclusions By using the absorbed dose to the kidneys as a limiting factor, treatment with 177 Lu-octreotate can be individualized, e.g., overtreatment can be avoided and patients with the potential to receive additional treatment can be identified. Further studies are needed to define tolerance doses to the kidneys so that treatment can be optimized.