hepatitis C virus/HCV NS5B protein (IC50 < 28 nM)

当与 pegIFN/RBV 联合使用以及与其他 DAA（包括核苷 NS5B 抑制剂、NS5A 抑制剂和 HCV NS3 蛋白酶抑制剂）联合使用 2 种或 3 种药物时，Beclabuvir/贝拉布韦表现出协同或相加的抗病毒效果[2]。

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Beclabuvir是HCV NS5B RNA聚合酶的强效非核苷抑制剂，在体外对HCV基因型1、3、4、5和6具有纳摩尔活性。Beclabuvir（原名BMS-791325）是一种强效的非核苷NS5B聚合酶抑制剂，结合NS5B拇指口袋1变构位点，对HCV GTs 1、3、4、5和6显示出纳摩尔活性，GT1a和GT1b 11的50%有效浓度（EC50）分别为3和6nm。在体外，Beclabuvir与聚乙二醇干扰素/RBV以及与一系列DAAs的2或3种药物组合（如HCV NS3蛋白酶抑制剂、NS5A抑制剂和/或核苷NS5B抑制剂）显示出相加或协同的抗病毒活性[2]。

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Beclabuvir是HCV NS5B RNA依赖性RNA聚合酶的变构抑制剂。已知的HCV NS5B变构抑制剂靶向聚合酶上的四个不同位点。酶的结构类似于手，位点I和II位于“拇指”结构域，位点III和IV位于“手掌”结构域。靶向不同结合位点的变构抑制剂彼此之间没有交叉抗性。因此，这些抑制剂可能与NS5B的其他变构抑制剂以协同或非拮抗方式相互作用。Beclabuvir是一个拇指部位1-NS5B聚合酶配体。一般来说，这些化合物抑制RNA复制的起始步骤，而不是伸长步骤。Beclabuvir已被证明可以同等抑制从头合成和引物依赖性合成，比之前研究的化合物强5-75倍，因此据我们所知，它是基因型1（GT-1）NS5B聚合酶最有效的拇指位点1抑制剂。结合后，beclabuvir以时间依赖的方式抑制NS5B活性，从而阻止活性复制复合物的形成[1]。

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在体外，Beclabuvir能够以纳摩尔效力在50%抑制浓度（IC50）下抑制源自HCV基因型1、3、4和5的重组NS5B蛋白。在细胞培养中，倍氯布韦分别在3 nM和6 nM的50%有效浓度（EC50s）下阻碍基因型1a和1b的HCV亚基因组复制子的复制。对于基因型3a、4a和5a，观察到类似的值（3至18nM）。对于基因型6a，EC50值显示出更多的变异性（9至125 nM），而与基因型2相比，效力较弱（EC50，87至925 nM）。对一组哺乳动物病毒（鼠疫病毒、牛病毒性腹泻病毒）或人类DNA聚合酶α、β、γ缺乏活性（EC50s>4μM）（IC50值>25μM）表明其特异性，同时细胞毒性浓度（50%）比HCV EC50高出3000倍以上。此外，当与其他HCV抑制剂如达卡他韦、阿舒那韦和人λ1 IFN联合使用时，beclabuvir对复制子抑制显示出相加的协同作用。此外，最近的一项体外研究表明，在四联治疗方案中添加Beclabuvir和sofosbuvir（达克拉他韦/阿舒那普利/贝克拉布韦/索非布韦）可以在5天的治疗时间内有效清除细胞中的达克拉他维/阿舒那普利耐药复制子[1]。

研究人员分析了DCV/ASV/BCV（Beclabuvir）治疗HCV感染小鼠和慢性肝炎患者的疗效。人肝细胞嵌合小鼠注射了从DAA初治患者或DCV/ASV治疗失败患者获得的血清样本，然后单独或与BCV联合使用DCV/ASV治疗4周。DCV/ASV治疗成功地消除了DAA初治患者HCV感染小鼠中的病毒。DCV/ASV治疗失败的HCV感染小鼠在DCV/ASV治疗期间出现了病毒突破，通过直接测序观察到NS5A-L31V/Y93H HCV耐药相关变异（RAV）的出现。DCV/ASV/BCV治疗抑制了NS5A-L31V/Y93H突变的HCV感染小鼠的病毒突破，但在停止治疗后，HCV随着NS5B-P495S变体的出现而复发。还分析了三联疗法对HCV感染患者的疗效；1名DAA幼稚患者和4名DAA治疗失败的患者接受了12 DCV/ASV/BCV治疗数周。一名DAA初治患者和一名DCV/ASV/BCV治疗失败的DCV/ASV患者实现了持续的病毒学应答；然而，其他先前DCV/ASV和/或sofosbuvir/ledipasvir治疗失败的患者发生了HCV复发。对于之前DAA治疗失败的NS5A RAV患者，DCV/ASV/BCV治疗似乎疗效有限。[3]

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在感染 HCV 基因型 1（全球最流行的基因型）的患者中，Beclabuvir/贝拉布韦、阿舒瑞韦和达拉他韦的组合可提供非常高的病毒根除率（约 90%）[1]。
在一项双盲、安慰剂对照研究中，24名患有慢性HCV基因型1感染的患者（每个给药队列中随机分配5:1）接受了单次每日递增剂量的Beclabuvir（100、300、600或900 mg）或安慰剂治疗，这些患者都是干扰素初治和有经验的。在2至4小时之间观察到峰值贝拉布韦浓度，t1/2为6.8至9.4小时。尽管t1/2似乎低于10小时，但24小时可实现的暴露量大大超过了体外建立的有效浓度。最大抗病毒反应与血浆药物暴露量相关，20名接受药物治疗的患者中有12名在给药后24小时（范围12-48小时）达到中值。在所有剂量的药物中，观察到病毒RNA的显著减少（在1 log10和超过3 log10 IU/ml之间）。两名患者达到了观察到的最高HCV RNA最大减少量，一名患者在600mg队列中（给药前基线，6.6 log10IU/ml），一名在900mg队列中（剂量前基线，6.5 log10IU/ml），其病毒载量在给药后24小时下降了3.4 log10UI/ml。

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无干扰素联合试验[1]
在一项II期研究和两项III期研究中评估了给予慢性HCV感染患者的3种DAAs、NS5A抑制剂达卡他韦（DCV）、NS3/4蛋白酶抑制剂阿舒那普利（ASV）和非核苷类NS5B聚合酶抑制剂Beclabuvir（BCV）的全口服固定剂量组合的疗效和安全性：i）AI443-014，这是一项针对初次治疗的GT-1和GT-4患者进行的II期研究，以及聚乙二醇干扰素/RBV（利巴韦林）先前无效反应的GT-1患者。本研究探讨了DCV-TRIO治疗（DCV-ASV-BCV）12或24周的安全性和有效性；ii）UNITY-1（AI443-102）是一项针对未接受治疗和有治疗经验的非肝硬化GT-1患者进行的III期研究。本研究评估了DCV TRIO治疗12周的安全性和有效性；iii）UNITY-2（AI443-113）是一项针对初次治疗和有治疗经验的GT-1代偿性肝硬化患者进行的iii期研究。本研究评估了DCV TRIO治疗加RBV治疗12周。

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本研究评估了Beclabuvir与聚乙二醇干扰素α-2a（pegIFN）和利巴韦林（RBV）联合治疗HCV基因型1的疗效和安全性。在这项随机（1:1:1）、双盲、安慰剂对照、剂量范围为2a期的研究中，39名慢性感染HCV基因型1的未接受治疗的患者接受了48周的贝拉布韦（75mg或150mg）加聚乙二醇干扰素（180μg）和红细胞毒素（1000mg/天[<75kg]或1200mg/天[≥75kg]）治疗，与单独使用聚乙二醇干扰素/RBV相比。76.9%（10/13）的患者接受75 mg倍氯布韦治疗，38.5%（5/13）接受150 mg倍氯布韦治疗，而仅接受聚乙二醇干扰素/RBV治疗的患者为0%，达到了延长快速病毒学反应的主要疗效终点（在治疗第4周和第12周无法检测到HCV RNA）。在所有次要疗效终点（包括随访第12或24周的持续病毒学应答）中，接受75 mg贝拉布韦治疗的患者的应答率较高。三名患者在治疗中出现病毒学突破，均在贝拉布韦150mg治疗组。Beclabuvir在两种剂量下均具有良好的耐受性，最常见的不良事件（头痛、疲劳、恶心、食欲下降、易怒、抑郁和失眠）与聚乙二醇干扰素/RBV观察到的不良事件一致。总之，当与聚乙二醇干扰素/RBV联合使用治疗慢性HCV GT1时，倍氯布韦既有效又耐受良好，支持将倍氯布威作为HCV GT1全口服方案的一部分进行研究。[2]

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总体而言，69名患者接受了筛查，39名患者被随机分配；其中，29名患者完成了研究（图S1）。除了与其他组相比，Beclabuvir75mg组的男性比例较低，白人患者和IL28B（rs12979860）CC基因型患者比例较高外，三组的基线特征总体上是平衡的（表S1）。

与聚乙二醇干扰素/RBV组（0%）相比，Beclabuvir75mg（76.9%）和150mg（38.5%）组的患者比例更高，达到了eRVR的主要疗效终点（图1）。贝拉布韦75 mg组的患者对次要疗效终点RVR、cEVR、SVR12和SVR24的反应率最高（图1）。当将缺失测量值的患者排除在分析之外时，也得到了类似的结果（在治疗分析中；图S2）。与安慰剂相比，对于IL28B CC和非CC基因型，贝克拉布韦治疗组的反应率通常也更高（图1），尽管数字很小。贝克拉布韦75 mg组与150 mg组的反应率较高可由两个因素解释：（i）150 mg组中IL28B（rs1297860）CC基因型患者的比例（15%）低于75 mg组（46%），已知与非CC基因型14-16相比，IL28B（rs 1297860，CC基因型与对基于聚乙二醇干扰素/红细胞疫苗的治疗方案的反应率更高；（ii）150 mg治疗组中在治疗后第24周HCV RNA数据缺失的患者比例更高。当考虑到缺失的数据时，150mg治疗组的SVR24发生率有所改善，贝拉布韦150mg组和安慰剂组的SVR22发生率观察值分别为71%（5/7）和90%（9/10）。

在Beclabuvir75mg组中，没有患者在治疗后出现病毒学突破或复发；在四名没有SVR24的患者中，一名患者在治疗结束时检测到HCV RNA，而其余3名患者（在治疗后随访第24周之前均检测不到HCV RNA）在此时间点之前丢失了第24周的治疗后数据，无法进行随访，或因其他原因（监禁）而中断治疗。在贝拉布韦150mg组中，在8名没有SVR24的患者中，3名患者在治疗结束时出现病毒学突破，1名患者检测到HCV RNA；未观察到治疗后复发。其余四名患者（在治疗后第24周之前均检测不到HCV RNA）要么在治疗后24周丢失了RNA数据（n=1），要么失去了随访（n=3）。在安慰剂组中，在8名没有SVR24的患者中，2名在治疗结束时检测到HCV RNA，3名在治疗后复发，而其余3名患者（在治疗后第24周之前均检测不到HCV RNA）缺少RNA数据或撤回同意书。

在三名病毒学突破的患者中（所有Beclabuvir150mg），所有患者均患有GT1a感染，为IL28B非CC基因型，并在突破时有NS5B替换A421V和P495A/L/S的证据；一名患者在基线时也使用了NS5B替代M426L。观察到所有病毒学突破的患者在A421和P495处都有GT1a和NS5B变异，这与贝克拉布韦和其他拇指口袋1 NS5B抑制剂的先前数据一致。P495的变体是拇指口袋-1抑制剂的标志性抗性相关替代，之前在单独存在贝拉布韦和与NS3抑制剂asunaprevir联合存在的GT1a复制子细胞体外传代后观察到A421V[2]。

在体外研究中，与NS5B遗传变异（野生型、L30S和P495L）的结合分析揭示了该药物的两步缓慢结合机制。详细地说，在基于基因型1的复制子中，由Beclabuvir/BCV选择的抗性替代大多映射到NS5B氨基酸495（P495A/S/L/T），因此可以认为这是唯一具有临床相关性的抗性变体。对于P495，初始复合物形成和解离的速率与野生型相似，但第二步的动力学明显更快。这与停留时间缩短有关，最终转化为抑制剂效力的降低。相比之下，BCV对L30S的效力大致等于野生型聚合酶。因此，L30S突变的检测被认为与临床无关。
关于基因型特异性抗性谱，GT1a对Beclabuvir/BCV的抗性屏障最高，而GT6a的抗性屏障最低。至少在基于基因型3至6的复制子系统中，NS5B拇指结构域第494和495位的置换赋予了不同水平的BCV抗性。然而，没有观察到对NS5A或NS3蛋白酶抑制剂的交叉耐药性。关于6a亚型，值得注意的是，A494多态性（赋予BCV降低的效力）存在于欧洲HCV数据库中21%的序列中[1]。

Patients and Methods [2]
This was a randomized (1:1:1), double-blinded, placebo-controlled, dose-ranging phase 2a study (AI443-012; ClinicalTrials.gov: NCT 01193361) evaluating the safety and efficacy of Beclabuvir combined with pegIFN/RBV in treatment-naive adults chronically infected with HCV GT1. Eligible patients received 48 weeks of twice-daily oral beclabuvir at 75 mg, beclabuvir at 150 mg, or placebo, each administered in combination with once-weekly subcutaneous pegIFN (180 μg) and twice-daily oral RBV (weight-based dosing of 1000 mg/day [<75 kg] or 1200 mg/day [≥75 kg]). The duration of post-treatment follow-up was 24 weeks (in patients with undetectable HCV RNA at end of treatment) or 48 weeks (in patients with detectable HCV RNA at end of treatment or relapse).

Patients were required to have HCV RNA ≥10–5 IU/mL (COBAS TaqMan HCV Test 2.0; Roche Molecular Diagnostics, Pleasanton, California; lower limit of quantitation [LLOQ] 25 IU/mL) at screening, with no evidence of cirrhosis by liver biopsy within 24 months of randomization. Key exclusion criteria included >4 weeks of prior treatment with interferon or RBV within 6 months prior to randomization; alanine aminotransferase (ALT) ≥5 × upper limit of normal (ULN); total bilirubin ≥34 μmol/L (≥2 mg/dL) or direct bilirubin >ULN; international normalization ratio (INR) ≥1.7; confirmed creatinine clearance ≤50 mL/min; or concurrent diagnosis of chronic hepatitis B infection, HIV infection, hepatocellular carcinoma or other non-HCV liver disease.

The primary safety endpoints were the incidence of serious adverse events (SAEs) and discontinuations of study therapy for AEs. The primary efficacy endpoint was the proportion of patients with extended rapid virologic response (eRVR), defined as undetectable (Beclabuvir and its metabolite BMS-794712, and associations between antiviral activity or safety of beclabuvir and host IL28B genotype or beclabuvir exposure.

Population sequencing of NS5B was performed at baseline, and for all Beclabuvir-treated patients experiencing futility (defined as [i] virologic breakthrough [increase in HCV RNA >1 log10 IU/mL above nadir, or HCV RNA ≥LLOQ following a confirmed undetectable measurement on treatment]; [ii] <1 log10 decrease in HCV RNA at week 4; [iii] failure to achieve EVR [defined as <2 log10 IU/mL decrease in HCV RNA at week 12]; or [iv] detectable HCV RNA at week 12 and ≥LLOQ at week 24) or relapse (undetectable HCV RNA at end of treatment followed by confirmed detectable HCV RNA at any post-treatment visit) and with HCV RNA ≥1000 IU/mL.

Pharmacokinetics and metabolism [1]
Optimization of the properties of an early series of NS5B polymerase inhibitors led to a promising group of alkyl bridged piperazine carboxamide antiviral compounds and the discovery and preclinical characterization of Beclabuvir. In vitro beclabuvir was studied in human, rat, dog, and cynomolgus monkey liver microsomes. In human and monkey microsomes, Beclabuvir half-lives (t1/2) were 53 and 23 min, respectively, while in both the rat and dog assays t1/2 were > 200 min. Based on these data, the compound was evaluated in 24 h rat pharmacokinetic study. In this study, when dosed as a solution in PEG-400, the oral bioavailability was 66%, the volume of distribution of 2.7 liters/kg while following an intra-venous administration, plasma clearance resulted 3.5 ml/min/kg and plasma t1/2 was estimated to be 8.3 h.

Plasma and liver exposures in vivo, following oral dosing, in several animal species (rats, dogs and monkeys) indicated that Beclabuvir has a hepatotropic disposition (liver-to-plasma ratios ranging from 1.6- to 60-fold across species). After twenty-four hours from administration, liver exposures across all species tested were greater than or equal to 10 -fold above the inhibitor EC50s observed with HCV genotype 1, 3, and 5 replicon EC50s; between 6.7- and 40-fold above GT 4 replicon EC50s; and 1.5- to 14-fold above GT 6 replicon EC50s.

Exposure to Beclabuvir in terms of maximum drug concentration (Cmax) and area under the plasma concentration-time curve (AUCinf) resulted dose dependent and more than dose proportional, with point estimates and 90% confidence intervals of about of 1.1 (0.99 to 1.22) for Cmax and 1.18 (0.99 to 1.36) for AUCinf, accordingly with the expectation of once- or twice-daily dosing. In replicon cultures, the protein-adjusted EC90 value resulted lower than plasma concentrations at all doses (52 ng/ml) within 1 h of dosing and at 24 h in all patients. Therefore, a satisfying antiviral responses can be expected for repeated administration even at the lowest tested doses (100 mg) while single doses above 300 mg provide little additional antiviral benefit. Moreover, Beclabuvir is metabolized to an equipotent compound (BMS-794712) which shows a similar pharmacokinetic profile, with a plasma exposure corresponding approximately to 22% of the parent value, hence contributing significantly to the total antiviral activity. In several clinical trials (see later), beclabuvir has been administered together with daclatasvir and asunaprevir. As all of these drugs are CYP3A4 substrates, OATP1B1 inhibitors and P-glycoprotein inhibitors, the potential drug to drug interactions of the triple combination have been investigated in a PK substudy of trial AI443014 in which 32 treatment-naive, HCV GT 1-infected, non-cirrhotic patients were treated for 12 or 24 weeks with daclatasvir (60 mg q.d.), asunaprevir (200 mg bis in die [b.i.d.]), and beclabuvir at two doses (75 mg b.i.d. or 150 mg b.i.d.). The addition of beclabuvir to daclatasvir and asunaprevir did not show any clinically meaningful interaction.

Even though DCV, ASV and Beclabuvir/BCV are primarily excreted in feces (renal excretion resulting < 10% of the total elimination) there are concerns that indirect mechanisms resulting from chronic kidney disease can equally modify the non-renal clearance of the drugs. For this reason, the open-label, multiple-dose AI443110 study assessed the pharmacokinetics and safety of DCV, ASN and BCV in 41 HCV-uninfected subjects (33 patients with different stages of renal impairment and 8 healthy controls with normal renal function). In subjects with moderate and severe renal impairment, mean concentrations of DCV, ASV, Beclabuvir/BCV and BMS-794712 were higher than in subjects with normal renal function. With respect to subjects with end stage renal disease (ESRD) on hemodialysis (HD), mean concentrations of DCV, BCV and BMS-794712 were comparable to subjects with normal renal function, while mean concentrations of ASV were lower. In patients with renal impairment, Cmax and AUCtau of the drugs were higher than among patients with normal renal function, particularly in subjects with severe renal impairment. Subjects with ESRD showed exposures generally comparable to the subjects with normal renal function due to HD and, after HD, DCV unbound PK parameters were lower when compared with healthy subjects. Cmax and AUCtau increased with decreasing creatinine clearance for DCV, ASV, BCV and BMS-794712 in primary regression analysis (excluding patients on HD), mainly in subjects with severe renal impairment (ranging from 42 to 105%).

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Median time to maximum plasma concentrations (Tmax) for Beclabuvir and its metabolite BMS-794712 were 2 h at each dose (Fig. S3). Exposure to both Beclabuvir and BMS-794712 at treatment week 12 was greater than dose proportional, with a metabolite:parent AUC ratio of ~0.23–0.25, which is consistent with previous single-dose data (100–900 mg) from a beclabuvir phase 1 study 12. No association was observed between composite trough concentrations of beclabuvir and achievement of a virologic response (eRVR, SVR24, RVR, cEVR, SVR12; Fig. S4a and data not shown), incidence of SAEs, or discontinuations for AEs (Fig. S4a). There was also no continuous association between drug exposure and changes from baseline in select clinical laboratory endpoints, including total bilirubin (Fig. S4b), ALT, haemoglobin or absolute neutrophils (data not shown); however, the caveat exists that trough levels are an indirect indication of peak exposure. [2]

Clinical trials: tolerability [1]
In the single-ascending-dose study of Beclabuvir/BCV in monotherapy, tolerability and safety profile was good. No death, SAE (Serious Adverse Event) or discontinuation due to AEs were reported. Recorded AEs were mild, except for two moderate gastrointestinal events in the 900-mg cohort, maybe due, at least partially, to a high capsule burden (18 capsules). Overall, the most frequent on-treatment observed AEs were nausea, vomiting, and headache (all the three symptoms recorded in 2/29 patients).

In IFN-based regimens, Beclabuvir/BCV was well tolerated at both doses (75 and 150 mg b.i.d.), and the most commonly observed AEs (headache, fatigue, nausea, decreased appetite, irritability, depression and insomnia) were consistent with those observed with pegIFN/RBV alone.

In the trials that evaluated the drug in combination with DCV and ASV, AEs led to treatment discontinuations occurred in two patients, three patients and one patient, in AI443-014, UNITY-1 and UNITY-2, respectively.
In AI443-014, there were six SAEs in GT-1 patients and no SAEs in GT-4 patients; there were no deaths. In treatment-naive GT1 patients, there were three SAEs, one in the Beclabuvir/BCV 75-mg arm (esophageal tumor, unrelated to the combination therapy, which led to treatment discontinuation) and two in the Beclabuvir/BCV 150-mg arm (one of which- throat tightness, related to the combination therapy – led to treatment discontinuation). The most frequent on-treatment AEs (≥ 10%) were headache, diarrhea, fatigue and nausea, in order of decreasing frequency. In prior null responders, three SAEs (cervical radiculopathy, syncope and psychotic disorder with onset 7 days posttreatment) and 1 grade 3 AE (syncope) occurred in the study; all four events occurred with 24 weeks of treatment and were considered unrelated to study medications. No grade 4 AEs were observed. The most common (≥ 10%) AEs included headache, fatigue, pruritus, diarrhea and upper respiratory tract infection. With respect to GT-4 patients, no SAE, grade 3/4 AE, or death was reported. The most commonly reported AEs in GT-4 patients (occurring in ≥ 10% of patients in either group) were headache (29% overall), insomnia (19%), nausea (14%) and pain (14%).

In UNITY-1, there were seven SAEs and one death (posttreatment); none were considered related to treatment. Headache, fatigue, diarrhea and nausea were the most commonly reported AEs (reported for > 10% of patients). AEs led to treatment discontinuation in three (< 1%) patients.

In UNITY-2, there were three SAEs considered related to treatment, with no deaths. Fatigue, headache, nausea, diarrhea, insomnia and pruritus were the most commonly reported AEs (reported for ≥ 10% of patients). On-treatment hemoglobin levels of < 9 g/dl occurred in 5% of patients who received the three DAAs plus RBV and in none of the patients in the RBV-free groups. One patient discontinued DAA treatment because of AEs.

With respect to the open-label, multiple-dose AI443110 study carried out in uninfected-HCV patients with normal or impaired renal function, no death or SAE was reported after the administration of DCV TRIO. One patient discontinued the study drugs because of an AE. A moderate increase of blood uric acid related to study drugs was reported in one subject in the moderate renal impairment group. During the study, 29% of patients with renal impairment experienced one or more AEs, mostly mild in intensity and transient, while no AEs were reported in healthy patients. No clinically relevant laboratory abnormalities were graded as AEs. In conclusion, DCV-TRIO resulted to be generally well tolerated both in patients with renal impairment and in subjects with normal renal function. Patients with renal impairment do not require dose adjustment of the drugs, except subjects with severe renal disease not on HD treatment, who should receive DCV-TRIO once daily.

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Beclabuvir was well tolerated at both doses, with no unexpected safety events (Table 1). No deaths were reported. The nature and incidence of on-treatment AEs were similar across the three groups (≥92%), with the most common AEs typically associated with pegIFN/RBV treatment. The most frequent on-treatment grade 3/4 laboratory abnormalities were haematologic and were also events expected with pegIFN/RBV. While on treatment and during post-treatment follow-up, three patients experienced SAEs; of these, two patients had SAEs considered unrelated to study drug. The third patient (beclabuvir 75 mg) had grade 3 anaemia with grade 2 leukopenia at post-treatment follow-up week 4, which were considered related to study drug. Six patients discontinued from study therapy due to AEs (one receiving 75 mg Beclabuvir, two receiving 150 mg beclabuvir, and three receiving placebo). Four discontinuations were protocol-mandated for confirmed conjugated hyperbilirubinemia (bilirubin ≥3 × baseline and >ULN) within the first 2 weeks (days 5–10; one in each beclabuvir arm, two in placebo arm). All four events were mild (grade 1) or moderate (grade 2) in intensity, with direct bilirubin levels ranging from 0.4 to 1.0 mg/dL (normal range, 0–0.2 mg/dL). Bilirubin abnormalities resolved completely or returned to just above baseline in three patients following discontinuation of all study drugs, but persisted in 1 placebo patient who initiated commercial pegIFN/RBV treatment. [2]

[1]. Beclabuvir for the treatment of hepatitis C. Expert Opin Investig Drugs. 2015;24(8):1111-21.

[2]. A randomized, placebo-controlled study of the NS5B inhibitor beclabuvir with peginterferon/ribavirin for HCV genotype 1. J Viral Hepat. 2015 Aug;22(8):658-64.

[3]. Limitations of daclatasvir/asunaprevir plus beclabuvir treatment in cases of NS5A inhibitor treatment failure. J Gen Virol. 2018 Aug;99(8):1058-1065.

Beclabuvir has been used in trials studying the treatment of Hepatitis C, Chronic.
Beclabuvir is a non-nucleoside, polymerase inhibitor of the hepatitis C virus (HCV) nonstructural protein 5B (NS5B), a RNA-dependent RNA polymerase, with potential activity against HCV. Upon administration and after intracellular uptake, beclabuvir allosterically binds to the non-catalytic Thumb 1 site of viral HCV NS5B polymerase and causes a decrease in viral RNA synthesis and replication. The HCV NS5B protein is essential for the replication of the viral HCV RNA genome. HCV is a small, enveloped, single-stranded RNA virus belonging to the Flaviviridae family.

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Introduction: About 185,000,000 people worldwide are chronically infected with hepatitis C virus (HCV). Currently, the most successful HCV infection antiviral therapies reduce the chance of progression towards the advanced phases of the hepatopathy (liver cirrhosis, hepatocellular carcinoma and death). Recently, however, several new direct-acting antivirals against HCV are available or are in an advanced phase of clinical development.
Areas covered: This review focuses on Beclabuvir, an allosteric non-nucleotide inhibitor of HCV polymerase. The article covers its pharmacokinetics, mechanism of action, in addition to its tolerability and safety profile as well as its resistance pattern.
Expert opinion: The pharmacokinetic, efficacy and tolerability profile of Beclabuvir, as well as its barrier to resistance, are very favorable. In particular, the combination of beclabuvir with asunaprevir and daclatasvir achieves very high rates of viral eradication (about 90%) in patients infected with HCV genotype 1, which is the most common genotype worldwide. Therefore, beclabuvir represents a powerful weapon against HCV infection and has to be considered an optimal option in tailored IFN-free combinations.[1]

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The pharmacokinetics of Beclabuvir/BCV allows for two administrations per day. The co-administration of BCV with the protease inhibitor ASV and the NS5A inhibitor DCV for 12 weeks achieves rates of SVR of about 90% in patients with HCV genotype 1 infection. Few but very favorable data concern the efficacy of the same combination in patients with HCV genotype 4 infection. Data on other non-1 genotypes are currently lacking. Tolerability and safety of this drug are satisfactory.
Based on the above, Beclabuvir/BCV represents a powerful weapon against HCV infection and has to be considered an optimal option as a component of tailored IFN-free combinations.

The treatment of HCV infection is living an era of exciting and rapid changes. The availability of several antiviral combinations active in different genotypes and in different phase of the disease makes potentially curable every patient with HCV infection. However, several aspects need to be assessed such as: i) the tolerability and safety of DAAs in the advanced phase of the disease; ii) the real impact of viral clearance on survival and quality of life if the infection is cleared in an advanced stage. In other words, is there a point of no return beyond which the achievement of viral clearance is not associated with a meaningful clinical benefit? iii) the best combination in every situation; iv) the availability of the drug for all patients at a reasonable price; and v) the potential impact of viral clearance for patients with slight hepatic damage but HCV-related extra-hepatic damages.

Regarding the first two points, it is noteworthy that no study on Beclabuvir/BCV has assessed efficacy and safety in decompensated cirrhosis. This is likely due to the use of ASV in combination regimens which is contraindicated in advanced cirrhosis due to the risk of exposing the patient in Child-Pugh B/C class to increased ASV plasma levels because of an altered liver distribution of ASV in these subjects. We advocate clinical trials that would assess the efficacy and safety of Beclabuvir/BCV in association with other drugs to evaluate its real potential in the treatment of patients with HCV infection and advanced liver disease.

With respect to the choice of the best combination at the best price we underline that most patients enrolled in clinical trial were infected with HCV genotype 1. This is the most common genotype worldwide. However, for this genotype, we have several combinations that have similar excellent SVR rates such as sofosbuvir/ledipasvir, sofosbuvir/DCV, sofosbuvir/simeprevir, ombitasvir-paritaprevir-ritonavir and dasabuvir. What this new drug and the different combinations can add is, above all, an increase in the options for the physicians. This, from one side, makes possible a tailored therapy for the single patient due to the possible drug-drug interaction, presence of resistance or contraindications. From the other side, a large armamentarium of different drugs against HCV increases competition among pharmaceutical companies. A basic market role is that a large competition decreases the price of the goods. This can have very important consequences especially for developing countries that cannot afford the current high price of these drugs.

Finally, a frequent finding in common clinical practice is the management of patients with HCV extrahepatic diseases (such as mixed cryoglobulins or non-Hodgkin lymphoma) which can be life threatening and severely impair the quality of life Citation[76-78]. However, in several circumstances extrahepatic damages are not quantifiable. Indeed, HCV infection has been associated with some metabolic-related disorders such as atherosclerosis, diabetes mellitus and overall cardiovascular risk. Therefore, it is not surprising that some data show a reduction of cardiovascular-related mortality in HCV-patients who achieve an SVR Citation[79]. Some aspects of Beclabuvir/BCV use need to be assessed. They include the efficacy in non-1 genotype. In fact, despite an in vitro, pan-genotypic activity, clinical use to non-1 genotypes is limited to 21 patients with genotype 4; the potential drug-drug interaction of BCV which is a substrate of CYP3A4 and an inhibitor of OATP1B1 and P-glycoprotein. For this reason studies that evaluate the pharmacokinetic of BCV when combined with some commonly used drugs are awaited.

Therefore, Beclabuvir/BCV represents a valid drug that has a good tolerability and safety profile and, together with other antivirals is associated with an optimal efficacy against HCV in compensated phases of the diseases. [1]

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Median time to maximum plasma concentrations (Tmax) for Beclabuvir and its metabolite BMS-794712 were 2 h at each dose (Fig. S3). Exposure to both beclabuvir and BMS-794712 at treatment week 12 was greater than dose proportional, with a metabolite:parent AUC ratio of ~0.23–0.25, which is consistent with previous single-dose data (100–900 mg) from a Beclabuvir phase 1 study. No association was observed between composite trough concentrations of beclabuvir and achievement of a virologic response (eRVR, SVR24, RVR, cEVR, SVR12; Fig. S4a and data not shown), incidence of SAEs, or discontinuations for AEs (Fig. S4a). There was also no continuous association between drug exposure and changes from baseline in select clinical laboratory endpoints, including total bilirubin (Fig. S4b), ALT, haemoglobin or absolute neutrophils (data not shown); however, the caveat exists that trough levels are an indirect indication of peak exposure.

Together, these data show that Beclabuvir is effective and well tolerated in combination with pegIFN/RBV for the treatment of chronic HCV GT1, and support the use of beclabuvir in all-oral regimens. Based on these results and similar data involving the DAAs daclatasvir (DCV; NS5A inhibitor) and asunaprevir (ASV), a phase 2b study in GT1 was initiated with the triple DAA combination Beclabuvir (75 mg or 150 mg), DCV (60 mg) and ASV (200 mg). In a pilot cohort (N = 66), this all-oral combination achieved SVR12 in 92% of patients after 12 or 24 weeks of treatment, with response rates apparently independent of either IL28B genotype and treatment duration. Similar efficacy and safety findings with this three-DAA regimen, using either the 75-mg or 150-mg beclabuvir dose, were subsequently reported for a larger (N = 166) cohort of patients treated for 12 weeks. Further phase 3 studies of the triple regimen of beclabuvir (75-mg dose) plus DCV and ASV as a fixed-dose combination pill are being conducted, targeting treatment-naive as well as -experienced patient populations.[2]

C36H45N5O5S

659.84

659.314

C, 65.53; H, 6.87; N, 10.61; O, 12.12; S, 4.86

958002-33-0

958002-36-3 (HCl);958002-33-0;

49773361

White to off-white solid powder

1.5±0.1 g/cm3

1.722

4.71

113

1

7

6

47

1320

2

CN1CC2CCC(C1)N2C(=O)[C@]34C[C@H]3C5=C(C=CC(=C5)OC)C6=C(C7=C(N6C4)C=C(C=C7)C(=O)NS(=O)(=O)N(C)C)C8CCCCC8

ZTTKEBYSXUCBSE-VSBZUFFNSA-N

InChI=1S/C36H45N5O5S/c1-38(2)47(44,45)37-34(42)23-10-14-28-31(16-23)40-21-36(35(43)41-24-11-12-25(41)20-39(3)19-24)18-30(36)29-17-26(46-4)13-15-27(29)33(40)32(28)22-8-6-5-7-9-22/h10,13-17,22,24-25,30H,5-9,11-12,18-21H2,1-4H3,(H,37,42)/t24?,25?,30-,36-/m0/s1

(8S,10R)-19-cyclohexyl-N-(dimethylsulfamoyl)-5-methoxy-10-(3-methyl-3,8-diazabicyclo[3.2.1]octane-8-carbonyl)-12-azapentacyclo[10.7.0.02,7.08,10.013,18]nonadeca-1(19),2(7),3,5,13(18),14,16-heptaene-15-carboxamide

Beclabuvir; Beclabuvir [USAN:INN]; MYW1X5CO9S; Beclabuvir [USAN]; BMS-791325; BECLABUVIR [MI]; BECLABUVIR [INN]; ...; 958002-33-0;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ≥ 30 mg/mL (45.47 mM)

配方 1 中的溶解度: ≥ 2.5 mg/mL (3.79 mM) (饱和度未知) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将100 μL 25.0 mg/mL澄清DMSO储备液加入到400 μL PEG300中，混匀；然后向上述溶液中加入50 μL Tween-80，混匀；加入450 μL生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: ≥ 2.5 mg/mL (3.79 mM) (饱和度未知) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL澄清DMSO储备液加入900 μL 20% SBE-β-CD生理盐水溶液中，混匀。
*20% SBE-β-CD 生理盐水溶液的制备（4°C，1 周）：将 2 g SBE-β-CD 溶解于 10 mL 生理盐水中，得到澄清溶液。

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配方 3 中的溶解度: ≥ 2.5 mg/mL (3.79 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL 澄清 DMSO 储备液加入到 900 μL 玉米油中并混合均匀。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
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7、 以上所有助溶剂都可在 Invivochem.cn网站购买。