Para-aminohippurate, also known as p-aminohippuric acid (PAH), is used clinically to measure effective renal plasma flow. Preclinically, it was shown to reduce ¹⁷⁷Lu-DOTATOC uptake in the kidneys while improving bioavailability compared with amino acid (AA) coinfusion. We report the safety and efficacy of PAH coinfusion during peptide receptor radiotherapy in patients with neuroendocrine tumors. Methods: Twelve patients with metastatic or unresectable gastroenteropancreatic neuroendocrine tumors received ¹⁷⁷Lu-DOTATOC in 33 treatment cycles. Either 8 g of PAH or a mixture of 25 g of arginine and 25 g of lysine were coinfused. Safety was assessed by monitoring laboratory data, including hematologic and renal data, as well as electrolytes obtained before and 24 h after treatment. For radiation dosimetry, whole-body scans were performed at 1, 24, and 48 h and a SPECT/CT scan was performed at 48 h, along with blood sampling at 5 min and 0.5, 2, 4, 24, and 48 h after administration. Absorbed dose estimations for the kidneys and bone marrow were performed according to the MIRD concept. Results: In 15 treatment cycles, PAH was coinfused. No changes in mean creatinine level, glomerular filtration rate, and serum electrolytes were observed before or 24 h after treatment when using PAH protection (P ≥ 0.20), whereas serum chloride and serum phosphate increased significantly under AA (both P < 0.01). Kidney–absorbed dose coefficients were 0.60 ± 0.14 Gy/GBq with PAH and 0.53 ± 0.16 Gy/GBq with AA. Based on extrapolated cumulative kidney-absorbed doses for 4 cycles, 1 patient with PAH protection and 1 patient with AA protection in our patient group would exceed the 23-Gy conservative threshold. The bone marrow–absorbed dose coefficient was 0.012 ± 0.004 Gy/GBq with PAH and 0.012 ± 0.003 Gy/GBq with AA. Conclusion: PAH is a promising alternative to AA for renal protection during peptide receptor radiotherapy. Further research is required to systematically investigate the safety profile and radiation dosimetry at varying PAH plasma concentrations.

对氨基马尿酸，也称为对氨基马尿酸（PAH），临床上用于测量有效的肾血浆流量。临床前研究表明，与氨基酸 (AA) 混输相比，它可以减少肾脏中 ¹⁷⁷ Lu-DOTATOC 的摄取，同时提高生物利用度。我们报告了神经内分泌肿瘤患者肽受体放疗期间 PAH 混输的安全性和有效性。方法：12 名转移性或不可切除的胃肠胰神经内分泌肿瘤患者接受 ¹⁷⁷ Lu-DOTATOC 治疗 33 个周期。共注入 8 g PAH 或 25 g 精氨酸和 25 g 赖氨酸的混合物。通过监测实验室数据来评估安全性，包括血液学和肾脏数据，以及治疗前和治疗后 24 小时获得的电解质。对于辐射剂量测定，在 1、24 和 48 小时进行全身扫描，在 48 小时进行 SPECT/CT 扫描，并在 5 分钟以及术后 0.5、2、4、24 和 48 小时进行血液采样。行政。根据 MIRD 概念对肾脏和骨髓的吸收剂量进行估计。结果：在15个治疗周期中，PAH被合并。使用PAH保护时，治疗前或治疗后24小时平均肌酐水平、肾小球滤过率和血清电解质没有变化（P≥0.20），而AA治疗下血清氯和血清磷酸盐显着升高（均P<0.01）。 PAH 的肾脏吸收剂量系数为 0.60 ± 0.14 Gy/GBq，AA 的肾脏吸收剂量系数为 0.53 ± 0.16 Gy/GBq。根据 4 个周期的外推累积肾脏吸收剂量，我们患者组中 1 名具有 PAH 保护的患者和 1 名具有 AA 保护的患者将超过 23 Gy 保守阈值。骨髓吸收剂量系数为0.012±0。PAH 为 004 Gy/GBq，AA 为 0.012 ± 0.003 Gy/GBq。结论：PAH 是一种有前景的 AA 替代品，用于肽受体放疗期间的肾脏保护。需要进一步的研究来系统地研究不同多环芳烃血浆浓度下的安全性和辐射剂量测定。