Chang Shuai, Zhuang Daomin, Guo Wei, Li Lin, Zhang Wenfu, Liu Siyang, Li Hanping, Liu Yongjian, Bao Zuoyi, Han Jingwan, Song Hongbin, Li Jingyun
Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, China.
State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
PLoS One. 2016 Mar 1;11(3):e0149467. doi: 10.1371/journal.pone.0149467. eCollection 2016.
This study was designed to identify common HIV-1 mutation complexes affecting the slope of inhibition curve, and to propose a new parameter incorporating both the IC50 and the slope to evaluate phenotypic resistance.
Utilizing site-directed mutagenesis, we constructed 22 HIV-1 common mutation complexes. IC50 and slope of 10 representative approved drugs and a novel agent against these mutations were measured to determine the resistance phenotypes. The values of new parameter incorporating both the IC50 and the slope of the inhibition curve were calculated, and the correlations between parameters were assessed.
Depending on the class of drug, there were intrinsic differences in how the resistance mutations affected the drug parameters. All of the mutations resulted in large increases in the IC50s of nucleoside reverse transcriptase inhibitors. The effects of the mutations on the slope were the most apparent when examining their effects on the inhibition of non-nucleoside reverse transcriptase inhibitors and protease inhibitors. For example, some mutations, such as V82A, had no effect on IC50, but reduced the slope. We proposed a new concept, termed IIPatoxic, on the basis of IC50, slope and the maximum limiting concentrations of the drug. The IIPatoxic values of 10 approved drugs and 1 novel agent were calculated, and were closely related to the IIPmax values (r > 0.95, p < 0.001).
This study confirms that resistance mutations cannot be accurately assessed by IC50 alone, because it tends to underestimate the degree of resistance. The slope parameter is of very importance in the measurement of drug resistance and the effect can be applied to more complex patterns of resistance. This is the most apparent when testing the effects of the mutations on protease inhibitors activity. We also propose a new index, IIPatoxic, which incorporates both the IC50 and the slope. This new index could complement current IIP indices, thereby enabling predict the efficacy of pre-clinical drugs for which human pharmacokinetic is not available.
本研究旨在识别影响抑制曲线斜率的常见HIV-1突变复合体，并提出一个整合半数抑制浓度（IC50）和斜率的新参数来评估表型耐药性。
利用定点诱变技术，构建了22种HIV-1常见突变复合体。测定了10种代表性已批准药物和1种针对这些突变的新型药物的IC50和斜率，以确定耐药表型。计算了整合IC50和抑制曲线斜率的新参数值，并评估了各参数之间的相关性。
根据药物类别，耐药突变对药物参数的影响存在内在差异。所有突变均导致核苷类逆转录酶抑制剂的IC50大幅增加。在研究突变对非核苷类逆转录酶抑制剂和蛋白酶抑制剂抑制作用的影响时，突变对斜率的影响最为明显。例如，一些突变，如V8A，对IC50没有影响，但降低了斜率。我们基于IC50、斜率和药物的最大极限浓度提出了一个新的概念，称为IIPatoxic。计算了10种已批准药物和1种新型药物的IIPatoxic值，其与IIPmax值密切相关（r>0.95，p<0.001）。
本研究证实，仅通过IC50不能准确评估耐药突变，因为它往往会低估耐药程度。斜率参数在耐药性测量中非常重要，其作用可应用于更复杂的耐药模式。在测试突变对蛋白酶抑制剂活性的影响时，这一点最为明显。我们还提出了一个新的指标IIPatoxic，它整合了IC50和斜率。这个新指标可以补充当前的IIP指标，从而能够预测尚无人体药代动力学数据的临床前药物的疗效。
