Hall P D, Kreitman R J, Willingham M C, Frankel A E
College of Pharmacy, Medical University of South Carolina, Charleston 29425, USA.
Toxicol Appl Pharmacol. 1998 May;150(1):91-7. doi: 10.1006/taap.1998.8389.
Because the majority of acute myeloid leukemia (AML) blasts express the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor, we are developing a fusion toxin consisting of a truncated diphtheria toxin (DT388) linked to human GM-CSF for multi-drug resistant AML. Our goal was to determine the toxicity and pharmacokinetics of DT388-GM-CSF in C57BL/6 mice. Because human GM-CSF does not cross-react with the mouse GM-CSF receptor, the toxicity observed should be nonspecific toxicity of DT388. We injected C57BL/6 mice i.p. with 0.1, 0.5, 1.0, 1.5, 1.75, 2.0, 3.5, 5.0, or 10 micrograms/day of DT388-GM-CSF for 5 consecutive days. For pharmacokinetics, blood samples were drawn at 20, 40, 60, 120, and 180 min after i.p. administration of 81 micrograms/kg of DT388-GM-CSF. In mice, the LD10 of DT388-GM-CSF is between 84.4 (1.5) and 104.4 (1.75) micrograms/kg (microgram) when administered for 5 consecutive days. All mice receiving > or = 201 micrograms/kg (3.5 micrograms) for 5 consecutive days died. Histopathologic examination of morbid animals showed only renal toxicity with acute proximal tubular necrosis. DT388-GM-CSF is stable in vivo based on nonreducing SDS-PAGE gel of plasma samples of 125I-labeled DT388-GM-CSF injected i.p.. The peak concentration of DT388-GM-CSF was 3.3 x 10(-8) M at 40 min and exhibited a t1/2 of 24 min. Based on its half-life, DT388-GM-CSF concentrations in the plasma are above the concentration inhibiting 50% protein synthesis and inducing apoptosis in 50% of HL-60 cells (AML cell line) for 5.2 h. Only four of 17 mice developed a weak immune response (0.9-160 ng/mL) 3 weeks after treatment. DT388-GM-CSF exhibits a short t1/2, but concentrations exceed those required in vitro to inhibit AML cell lines.
由于大多数急性髓系白血病（AML）原始细胞表达粒细胞-巨噬细胞集落刺激因子（GM-CSF）受体，我们正在研发一种融合毒素，它由与人类GM-CSF连接的截短型白喉毒素（DT388）组成，用于治疗多药耐药AML。我们的目标是确定DT388-GM-CSF在C57BL/6小鼠中的毒性和药代动力学。由于人类GM-CSF与小鼠GM-CSF受体无交叉反应，观察到的毒性应为DT388的非特异性毒性。我们给C57BL/6小鼠腹腔注射0.1、0.5、1.0、1.5、1.75、2.0、3.5、5.0或10微克/天的DT388-GM-CSF，连续注射5天。为了研究药代动力学，在腹腔注射81微克/千克的DT388-GM-CSF后20、40、60、120和180分钟采集血样。在小鼠中，连续5天给药时，DT388-GM-CSF的LD10在84.4（1.5）至104.4（1.75）微克/千克（微克）之间。所有连续5天接受≥201微克/千克（3.5微克）的小鼠均死亡。对患病动物的组织病理学检查仅显示肾毒性伴急性近端肾小管坏死。基于腹腔注射125I标记的DT388-GM-CSF后血浆样本的非还原SDS-PAGE凝胶分析，DT388-GM-CSF在体内稳定。DT388-GM-CSF的峰值浓度在40分钟时为3.3×10-8 M，半衰期为24分钟。基于其半衰期，血浆中DT388-GM-CSF的浓度在5.2小时内高于抑制50%蛋白质合成并诱导50%的HL-60细胞（AML细胞系）凋亡的浓度。治疗3周后，17只小鼠中只有4只产生了微弱的免疫反应（0.9 - 160纳克/毫升）。DT388-GM-CSF半衰期较短，但浓度超过了体外抑制AML细胞系所需的浓度。
