ABSTRACT
This study characterizes aminoindole molecules that are analogs of Genz-644442. Genz-644442 was identified as a hit in a screen of ∼70,000 compounds in the Broad Institute's small-molecule library and the ICCB-L compound collection at Harvard Medical School. Genz-644442 is a potent inhibitor of
Plasmodium falciparum in vitro
(50% inhibitory concentrations [IC
50
s], 200 to 285 nM) and inhibits
P. berghei in vivo
with an efficacy of >99% in an adapted version of Peters' 4-day suppressive test (W. Peters, Ann. Trop. Med. Parasitol. 69:155–171, 1975). Genz-644442 became the focus of medicinal chemistry optimization; 321 analogs were synthesized and were tested for
in vitro
potency against
P. falciparum
and for
in vitro
absorption, distribution, metabolism, and excretion (ADME) properties. This yielded compounds with IC
50
s of approximately 30 nM. The lead compound, Genz-668764, has been characterized in more detail. It is a single enantiomer with IC
50
s of 28 to 65 nM against
P. falciparum in vitro
. In the 4-day
P. berghei
model, when it was dosed at 100 mg/kg of body weight/day, no parasites were detected on day 4 postinfection. However, parasites recrudesced by day 9. Dosing at 200 mg/kg/day twice a day resulted in cures of 3/5 animals. The compound had comparable activity against
P. falciparum
blood stages in a human-engrafted NOD
-scid
mouse model. Genz-668764 had a terminal half-life of 2.8 h and plasma trough levels of 41 ng/ml when it was dosed twice a day orally at 55 mg/kg/day. Seven-day rat safety studies showed a no-observable-adverse-effect level (NOAEL) at 200 mg/kg/day; the compound was not mutagenic in Ames tests, did not inhibit the hERG channel, and did not have potent activity against a broad panel of receptors and enzymes. Employing allometric scaling and using
in vitro
ADME data, the predicted human minimum efficacious dose of Genz-668764 in a 3-day once-daily dosing regimen was 421 mg/day/70 kg, which would maintain plasma trough levels above the IC
90
against
P. falciparum
for at least 96 h after the last dose. The predicted human therapeutic index was approximately 3, on the basis of the exposure in rats at the NOAEL. We were unable to select for parasites with >2-fold decreased sensitivity to the parent compound, Genz-644442, over 270 days of
in vitro
culture under drug pressure. These characteristics make Genz-668764 a good candidate for preclinical development.
摘要
本研究描述了作为 Genz-644442 类似物的氨基吲哚分子的特征。在对布罗德研究所的小分子化合物库和哈佛大学医学院的 ICCB-L 化合物库中的∼70,000 个化合物进行筛选时,发现 Genz-644442 是一个热门化合物。Genz-644442 是一种有效的恶性疟原虫抑制剂。
体外恶性疟原虫的强效抑制剂
(50%抑制浓度[IC
50
s],200 至 285 nM),并在体内抑制恶性疟原虫。
体内的
在彼得斯 4 天抑制试验(W. Peters,Ann. Trop. Med. Parasitol.)Genz-644442 成为药物化学优化的重点;合成了 321 种类似物,并进行了以下测试
体外
对
恶性疟原虫
和
体外
吸收、分布、代谢和排泄(ADME)特性。结果发现,这些化合物的 IC
50
s 约为 30 nM。对主要化合物 Genz-668764 进行了更详细的表征。它是一种单一对映体,IC
50
s 为 28 至 65 nM。
体外抗恶性疟原虫的作用。
.在为期 4 天的
疟原虫
模型中,按 100 毫克/千克体重/天的剂量给药时,感染后第 4 天未检测到寄生虫。然而,寄生虫在第 9 天再次出现。以 200 毫克/千克体重/天的剂量给药,每天两次,结果有 3/5 的动物痊愈。该化合物对
恶性疟原虫
的活性相当。
-scid
小鼠模型中对恶性疟原虫血液期的活性相当。Genz-668764的终末半衰期为2.8小时,以55毫克/千克/天的剂量口服,一天两次,血浆谷值水平为41纳克/毫升。为期七天的大鼠安全性研究显示,200 毫克/千克/天的剂量为无观测不良效应水平(NOAEL);在艾姆斯试验中,该化合物没有致突变性,对 hERG 通道没有抑制作用,对多种受体和酶也没有强效活性。采用异计量比例和
体外
ADME数据,预测Genz-668764的人体最小有效剂量为421毫克/天/70千克,在3天每日一次的给药方案中,该剂量可使血浆谷值水平保持在IC
90
以上。
恶性疟原虫
在最后一次给药后的至少 96 小时内,血浆谷值都将保持在抗恶性疟原虫 IC 90 以上。根据大鼠在无观测不良效应水平下的暴露量,预测人体治疗指数约为 3。在 270 天的体外实验中,我们无法筛选出对母体化合物 Genz-644442 的敏感性降低 2 倍的寄生虫。
体外
在药物压力下进行体外培养。这些特点使 Genz-668764 成为临床前开发的理想候选药物。