Efavirenz

前言 共价药物（Covalent drug）是指在结构中包含反应性的官能团，能与靶蛋白形成共价键，实现与靶蛋白长期结合，从而提供独特的药效学特征。从偶然发现到目标性设计，共价药物在多个疾病领域蓬勃发展，尤其是抗肿瘤领域。自KRAS靶点在癌症中的作用被发现以来，近30年间研究者使用传统药物发现方法一直没有突破这一靶点的不可成药性，而共价抑制剂Sotorasib（Lumakras）和Adagrasib（Krazati）打破了KRAS“不可成药靶点”的魔咒。近年来，多款共价药物成功上市，包括针对EGFR、BTK、KRAS等靶点的抑制剂。 细胞色素P450酶（以下简称CYP酶）是体内参与药物代谢最广泛的I相代谢酶，主要位于肝脏，参与约75%的小分子药物代谢。药物对CYP酶的抑制会引起联用药物的暴露量增加或活性代谢产物暴露量减少，造成潜在毒性或影响疗效。抑制评价分为可逆性抑制（Reversible inhibition）和时间依赖性抑制（Time-dependent inhibition, TDI）评价，其中TDI会造成更为严重的药物相互作用（Drug interaction, DDI）。 药物本身或其代谢后生成的反应性中间体与CYP酶的共价结合是TDI发生的机理之一，那么共价药物是否一定会发生TDI呢？共价药物的TDI风险比非共价抑制剂更高吗？如何评估TDI风险和解读TDI数据呢？本文分析了29个已上市的共价药物对CYP酶的TDI研究结果，并对体外TDI风险评估的方法和数据解读提供相关建议。 上市共价药物对CYP450酶的抑制结果分析 据报道，自1947年以来共117种共价药物获批[1]，已上市的共价药物主要涉及抗感染（青霉素、磷霉素）、抗病毒（奈马特韦）和抗肿瘤（奥西替尼、达克替尼）等治疗领域。本文检索了自2000年以来上市的共价药物对CYP酶的体外TDI结果，共整理出29个共价药物的数据，详见文末附表1。其中19个共价药物对至少一种CYP酶表现出TDI，约占65.5%。TDI在7种常见CYP酶的分布汇总如图1，有15个药物对CYP3A存在TDI，约占79%；其次是2C8，5个共价药物对其存在TDI，约占26%；对1A2和2B6存在TDI的共价药物都为3个，占比约16%；有1个共价药物对2C19存在TDI，占比约5%。19个共价药物对2C9和2D6不存在TDI或目前未见报道。 图1. 自2000年之后上市的具有TDI的共价药物在常见CYP酶的分布情况 一项体外[22]研究评估了14个蛋白激酶抑制剂对CYP2C8和CYP3A的TDI，结果表明经过与NADPH预孵育以后，11个激酶抑制剂对CYP3A的抑制效果增强，3个对CYP2C8的抑制效果增强，（如图2）。其中有8个已被文献报道为CYP3A的TDI抑制剂，另外3个在随后的研究中证实抑制CYP3A的IC50偏移率大于2倍。这14个药物并非共价药物，由此看来，非共价药物尤其是蛋白激酶抑制剂的TDI风险依然不容忽视。对于共价药物和非共价药物，TDI都是需要重点关注的内容。 图2. 蛋白激酶抑制剂与NADPH预孵育30min后抑制阿莫地喹N-去乙基化（CYP2C8）和咪达唑仑1'-羟化（CYP3A）的结果。BOSU, bosutinib; BOSU iso, bosutinib isomer 1; CRIZ, crizotinib; DASA, dasatinib; ERLO, erlotinib; GEFI, gefitinib; LEST, lestaurtinib; NILO, nilotinib; PAZO, pazopanib; SARA, saracatinib; SORA, sorafenib; SUNI, sunitinib. [22] 体外TDI风险评估的方法建议 监管机构和制药公司已经认识到评估TDI风险的重要性，人用药品技术要求国际协调理事会（ICH）发布的指导原则M12《Drug Interaction Studies》[23]于今年5月21日最终采纳。结合指南推荐，体外评估药物TDI风险的方法总结如下： “ 1 酶活性损失百分比、假一级 速率常数kobs和IC50偏移 早期药物发现阶段，需要高通量、快速筛选确定CYP酶的TDI潜力，可以通过单一化合物浓度下含和不含NADPH预孵育后损失百分比（%Activity loss），CYP酶活性降低（kobs）或多浓度的化合物含和不含NADPH预孵育后IC50值的偏移(IC50 shift)来判断化合物是否有TDI潜力。 “ 2 TDI抑制的动力学常数测定（kinact、KI） 评估CYP酶TDI的重要动力学常数包括最大失活速率常数（kinact）、导致半数最大失活的抑制剂浓度（KI）。采用不同浓度的化合物（至少6个）与酶源（即肝微粒体、肝细胞、重组酶系统）及NADPH进行第1次孵育（至少6个时间点），也称失活孵育；在特定的孵育时间后，将失活孵育混合物加入含有CYP同工酶探针底物的二次孵育当中，反应一定时间后，终止反应，并测量探针底物的代谢产物生成。计算失活后相对于没有抑制剂时所测得的活性的剩余百分比，剩余百分比与失活孵育的时间进行线性拟合作图，得到一系列一级衰减曲线，如图3a，直线斜率的负值即为一个浓度点的表观抑制速率（kobs）。用不同浓度下的表观抑制速率与化合物的浓度进行非线性拟合即可计算得到kinact和KI，如图3b。 图3. Verapamil的体外TDI动力学常数测定（kinact和KI） 测量kinact和KI的体外实验方法通常不适合早期药物发现项目中的高通量筛选。但从药物发现的角度，较大的kinact值和较小的KI值通常会增加CYP酶失活导致DDI的可能性。因此在临床前药物发现中，也可以通过kinact/KI比值衡量化合物CYP酶失活的效率，对同系列化合物进行排序。 案例分享与TDI数据的解读建议 Ritlecitinib是一种共价JAK3酪氨酸激酶抑制剂，主要用于治疗脱发症，尤其是斑秃和非节段型白癜风（NSV）。其共价抑制机制主要通过与JAK3催化域中的半胱氨酸残基（Cys-909）发生不可逆的共价结合来实现。这一残基在其他JAK家族成员中被丝氨酸残基所取代，这使得Ritlecitinib对JAK3具有高度的选择性[24, 25]。 Ritlecitinib在体外肝微粒体TDI评价体系中，被评估为CYP1A2和CYP3A的TDI抑制剂。其中，Ritlecitinib对CYP1A2（以咖啡因底物）代谢活性抑制常数分别是KI为327 μmol/L，kinact为0.0917 min-1。由于在测试的浓度范围内（3-200 μmol/L）未达到抑制饱和，因此无法确定对CYP3A（以咪达唑仑底物）代谢活性的KI或kinact，但kinact/KI估计为0.871 mL/min/μmol[20]。 在斑秃患者中，每日一次口服50 mg的Ritlecitinib后最大稳态游离药物浓度（Cmax,u）估计值1.1 μmol/L[20]，结合上述体外TDI参数，根据ICH M12指导原则[23]的基本方法初步评价TDI风险如表1。计算得到Ritlecitinib对CYP1A2的表观一级失活速率常数(Kobs)为0.001517 min-1。Kdeg是酶的表观一级降解速率常数，引用自指导原则，计算（kobs+kdeg）/kdeg的值为6.06，大于1.25，说明需关注Ritlecitinib潜在临床抑制风险。 表1. 基本模型预测Ritlecitinib对CYP1A2的TDI风险 注：kobs=(kinact*5*Cmax,u)/(KI+5*Cmax,u)，此处计算所使用数据引用自文献[20] 该药物开展了相应的临床DDI研究。Liu[26]等人在健康志愿者中开展的临床研究中发现，咖啡因（CYP1A2底物）与Ritlecitinib联合使用时，咖啡因的AUC和Cmax分别增加了约165%和10%，表明Ritlecitinib是CYP1A2的中等抑制剂，可以增加CYP1A2底物的暴露量。Ritlecitinib与CYP酶底物合用的临床DDI研究结果汇总如表2，Ritlecitinib与咪达唑仑（CYP3A底物）合用导致咪达唑仑的AUC和Cmax分别增加了约169%和81%，而其与Efavirenz（CYP2B6底物）和Tolbutamide（CYP2C底物）合用后，底物的暴露量变化不具有临床意义[27]。在Ritlecitinib药品说明书中，提示与CYP3A和CYP1A2的底物合用时，可能增加不良反应风险，需考虑额外的监测或调整剂量。 表2. Ritlecitinib临床与CYP酶底物合用引起的暴露量变化 c: 合用Ritlecitinib相比于单独给药的Cmax和AUCinf的比值。 d: 报告了Efavirenz的AUC0-72。 以上结果整理自药品说明书。 TDI数据解读建议 药物研发早期可通过单一浓度下的酶活性降低(酶活性损失率%Activity loss或假一级速率常数kobs或多浓度点下IC50偏移(≥1.5)，检测化合物的TDI潜力； 如药物具有TDI潜力，可通过体外研究获得TDI的动力学参数kinact、KI，结合人体PK数据，应用模型排除或预测临床TDI风险。 结 语 本文整理的数据表明65%以上的共价药物表现出对CYP酶的TDI，而文献显示非共价药物如蛋白激酶抑制剂的TDI风险同样不容忽视，因此，不论是否为共价药物，均建议在研发早期考察TDI风险。 TDI引起的临床不良反应往往是极其严重的，如米贝拉地尔的撤市，其作为CYP3A的强TDI抑制剂，与其他3A的底物合用会引起严重的毒性反应，严重时导致死亡。对于存在TDI风险的药物，必要时通过体外实验获取抑制动力学参数kinact和KI，结合临床PK数据进行临床DDI风险的评估，如果体外数据和模型无法排除临床抑制风险，则应使用敏感探针底物进行临床DDI研究。 药明康德DMPK已经建立了一套专门针对共价药物的药代动力学研究体系，其中包括早期的高通量筛选、共价药物多样化的体内外代谢模型与方法、丰富的体外ADME试验类型、以及14C标记化合物的合成和相应的ADME技术平台，可以支持客户加速共价药物的研发和申报。 附表1. 29个共价药物对CYP酶的TDI结果汇总  （下滑查看更多） a: 结果引用自药品说明书。 b: 由于测试浓度（3-200 μM）下抑制未被饱和，无法计算准确KI和kinact值。 参考文献： [1] Journal of Medicinal Chemistry 2022 65 (8),5886-5901 DOI: 10.1021/acs.jmedchem.1c02134 [2] Suchy D, Łabuzek K, Stadnicki A, Okopień B. Ezetimibe--a new approach in hypercholesterolemia management. Pharmacol Rep. 2011;63(6):1335-48. doi: 10.1016/s1734-1140(11)70698-3. PMID: 22358082. [3] Investigation of drug-drug interaction potential of bortezomib in vivo in female Sprague-Dawley rats and in vitro in human liver microsomes；Drug Metab Dispos. 2006 Apr;34(4):702-8. [4] M. F Moghaddam, et al. Drug Metabolism Letters, 2014, 8, 19-30. [5] NDA 22-134: https://www.fda.gov/files/drugs/published/22134-Alcaftadine-ClinPharm-PREA.pdf [6] Chapron B, Risler L, Phillips B, Collins C, Thummel K, Shen D. Reversible, time-dependent inhibition of CYP3A-mediated metabolism of midazolam and tacrolimus by telaprevir in human liver microsomes. J Pharm Pharm Sci. 2015;18(1):101-11. doi: 10.18433/j3288c. PMID: 25877445. [7] Wang, Z., Yang, J., Kirk, C., Fang, Y., Alsina, M., Badros, A., Infante, J. R. (2012). Clinical Pharmacokinetics, Metabolism, and Drug-Drug Interaction of Carfilzomib. 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[12] NDA 209776: https://www.accessdata.fda.gov/drugsatfda_docs/nda/2017/209776Orig1s000PharmR.pdf [13] Report on the Deliberation Results: https://www.pmda.go.jp/files/000240418.pdf [14] Zhang H, Ou YC, Su D, Wang F, Wang L, Sahasranaman S, Tang Z. In vitro investigations into the roles of CYP450 enzymes and drug transporters in the drug interactions of zanubrutinib, a covalent Bruton's tyrosine kinase inhibitor. Pharmacol Res Perspect. 2021 Dec;9(6):e00870. doi: 10.1002/prp2.870. PMID: 34664792; PMCID: PMC8524670. [15] Report on the Deliberation Results: https://www.pmda.go.jp/files/000237315.pdf [16] NDA 214665: https://www.accessdata.fda.gov/drugsatfda_docs/nda/2021/214665Orig1s000MultidisciplineR.pdf [17] NDA 215301: https://www.accessdata.fda.gov/drugsatfda_docs/nda/2021/215310Orig1s000MultidisciplineR.pdf [18] KRAZATI 200 mg film-coated tablets: ANNEX I [19] Heather Eng et al, Disposition of Nirmatrelvir, an Orally Bioavailable Inhibitor of SARS-CoV-2 3C-Like Protease, across Animals and Humans; Drug Metab Dispos. 2022 May;50(5):576-590. [20] Litfulo review report; https://www.pmda.go.jp/files/000266925.pdf [21] https://www.ema.europa.eu/en/documents/rmp-summary/skyclarys-epar-risk-management-plan_en.pdf [22] Drug Metab Dispos 42:1202–1209, July 2014, http://dx.doi.org/10.1124/dmd.114.057695 [23] ICH M12《Drug Interaction Studies》 [24] Xu H, Jesson MI, Seneviratne UI, et al. PF-06651600, a dual JAK3/TEC family kinase inhibitor. ACS Chem Biol. 2019;14(6):1235–42. [25] Telliez JB, Dowty ME, Wang L, et al. Discovery of a JAK3- selective inhibitor: functional diferentiation of JAK3-selective inhibition over pan-JAK or JAK1-selective inhibition. ACS Chem Biol. 2016;11(12):3442–51. [26] Liu J, Solan R, Wolk R, et all. Evaluation of the effect of ritlecitinib on the pharmacokinetics of caffeine in healthy participants. Br J Clin Pharmacol. 2023;89:2208–2215. [27] Pfzer Inc. LITFULO™ (ritlecitinib) capsules, for oral use: US prescribing information. 2023. https://www.accessdata.fda.gov/ drugsatfda_docs/label/2023/215830s000lbl.pdf. Accessed 26 Jul 2023.  （下滑查看更多） 作者：吴文萍，马虹莹，马利萍，周莹，金晶 编辑：姜利芳，钱卉娟，陈根富 设计：倪德伟，张莹莹 声明：发表/转载本文仅仅是出于传播信息的需要，并不意味着代表本公众号观点或证实其内容的真实性。据此内容作出的任何判断，后果自负。若有侵权，告知必删！ 长按关注本公众号  粉丝群/投稿/授权/广告等 请联系公众号助手 觉得本文好看，请点这里↓

- Key Insights from Viral Hepatitis, PBC, and MASH/Fibrosis Studies Highlight Gilead’s Ongoing Commitment to Advancing Life-Changing Liver Disease Research - FOSTER CITY, Calif.--(BUSINESS WIRE)--Gilead Sciences, Inc. (Nasdaq: GILD) today announced new research to be presented at The Liver Meeting ® 2024, hosted by the American Association for the Study of Liver Diseases (AASLD) from November 15-19 in San Diego, Calif. More than 40 abstracts will be presented with key data, including 11 abstracts reporting new data on primary biliary cholangitis (PBC). The data will include findings from the RESPONSE trial that demonstrate the efficacy and safety pro Livdelzi ® (seladelpar) in people living with PBC and compensated cirrhosis. Additionally, data will be presented on the effects of Livdelzi on pruritus (chronic itching), a symptom that has significant impact on the quality of life of people living with PBC, along with interim long-term efficacy and safety results from the ongoing ASSURE study. Beyond PBC, Gilead will be presenting an interim analysis of the Phase 3 MYR301 study, which is evaluating people living with hepatitis Delta virus (HDV) who received bulevirtide monotherapy (2 mg for 144 weeks; 10 mg for 144 weeks; or 10 mg for 96 weeks) for chronic HDV and have been off treatment for 48 weeks. The study is evaluating whether or not patients treated with bulevirtide monotherapy for 2-3 years maintained virological and biochemical responses one year after stopping treatment. An additional 144-week analysis of patient-reported outcomes for individuals treated with bulevirtide 2 mg will also be presented, adding to the wealth of long-term data for the treatment for chronic HDV. “We’re excited to share our latest research at The Liver Meeting, as we push the boundaries of what’s possible in liver disease treatment. The breadth of this research reflects Gilead’s unwavering dedication to advancing life-changing science and shaping healthier futures for people living with liver disease,” said Anu Osinusi, Vice President of Clinical Development for Hepatitis, Respiratory and Emerging Viruses, Gilead Sciences. “The depth and range of our data, spanning both viral and inflammatory liver diseases, underscores our commitment to making a meaningful impact at every stage of a person’s journey in liver disease. Our goals go far beyond treatment alone—our work spans awareness, education, screening, diagnosis, and long-term care, all intending to address unmet needs and enhance treatment outcomes.” Gilead will also present hepatitis C virus (HCV) data which will include safety and tolerability outcomes for Epclusa ® (velpatasvir/sofosbuvir) in pregnant individuals with chronic HCV (the STORC study). As a special population that is often excluded from clinical research, these results may help clinicians better support pregnant people living with HCV, which in turn may reduce the risk of transmission to infants. Furthermore, real-world findings from the SVR10K study on HCV will be showcased, demonstrating the effects of direct-acting antivirals against all HCV genotypes across diverse regions. Late-breaking data from a Phase 2a open-label study assessing the safety and efficacy of novel combination therapies for chronic hepatitis B virus (HBV) will also be presented by Gilead. Key Abstracts at AASLD 2024: ID Abstract Title PBC 164 Efficacy and Safety of Seladelpar in Patients with PBC and Compensated Cirrhosis in the Phase 3 Placebo-controlled RESPONSE Trial 167 Attenuation, Near Resolution, and Prevention of Pruritis in Patients with PBC Treated with Seladelpar: A Secondary Analysis of Patterns of Pruritis Change in the RESPONSE Trial 4339 Alkaline Phosphatase Changes with Seladelpar Across Subgroups of Primary Biliary Cholangitis Patients in the RESPONSE Trial 4342 Seladelpar and Reductions in Lipids in Patients with Primary Biliary Cholangitis with and without Statin use in the Phase 3 Placebo-controlled RESPONSE Study 4341 Long-term Safety of Seladelpar 10 mg with up to 5 Years of Treatment in Patients with Primary Biliary Cholangitis Primary sclerosing cholangitis (PSC) 151 Associations Between Biomarkers and Magnetic Resonance Imaging-derived ANALI Score in Patients with Primary Sclerosing Cholangitis: Analysis from the Phase 3 PRIMIS Study HDV 1147 Efficacy and Safety of BLV Monotherapy for Chronic Hepatitis Delta: Post Treatment Results through 48 Weeks after the End of Treatment from an Interim Analysis of a Randomized Phase 3 Study MYR301 1193 Patient-reported Outcomes among Patients with Chronic Hepatitis Delta Treated with Bulevirtide 2 mg: A Long-term Analysis of the Phase 3 MYR301 Trial at 144 Weeks 139 Long-term Bulevirtide Monotherapy in Patients with HDV-related Compensated Cirrhosis: Effectiveness, Safety and Clinical Outcomes from the Retrospective Multicenter European Study (SAVE-D) HCV 222 Safety, Tolerability, and Outcomes of Velpatasvir/Sofosbuvir in Treatment of Chronic Hepatitis C Virus during Pregnancy (STORC) 1455 The SVR10K Study: A Real-world Data with Pangenotypic Direct-acting Antivirals across Multiple Diverse Regions 1476 Hepatitis C Treatment Uptake Differs by Gender among a Commercially Insured Population in the United States HBV 1380 Results from a Phase 2a, Open-label Study to Evaluate the Safety and Efficacy of Novel Combination Therapies Containing VIR-2218, Selgantolimod, and Nivolumab for the Treatment of Chronic Hepatitis B 1252 Effectiveness and Safety of Tenofovir Alafenamide in Chronic Hepatitis B Patients with Suboptimal Response to Antiviral Therapy 1337 Characterization of Changes in Noninvasive Fibrosis Markers over 8 Years of Tenofovir-based Treatment in Chronic Hepatitis B Patients Enrolled in Two Phase 3 Trials Nonalcoholic steatohepatitis (NASH)/Fibrosis 1520 Prospective Validation of the Mediterranean Diet Adherence Screener (MEDAS) for Point-of-care Assessment of Diet Quality in Patients with Metabolic Dysfunction-associated Steatotic Liver Disease For more information, including a complete list of abstract titles being presented at the meeting, please visit the AASLD website . In July 2023, the European Commission (EC) granted full Marketing Authorization (MA) for bulevirtide 2 mg for the treatment of adults with chronic HDV and compensated liver disease. Bulevirtide’s conditional MA license in Great Britain was converted to a full MA in August 2023 and a full MA was granted in Switzerland and Australia in 2024. In regions where it is not approved, including the U.S., bulevirtide 2 mg is an investigational product. In these regions, health authorities have not established the safety and efficacy of bulevirtide. Bulevirtide 10 mg is an investigational product and has not been approved anywhere. Cilofexor and selgantolimod are investigational compounds and are not approved by the FDA or any other regulatory authority; their safety and efficacy have not been established. Please see below for the U.S. Indications and Important Safety Information, including BOXED WARNINGS, for Epclusa and Livdelzi. U.S. Important Safety Information And Indication for EPCLUSA BOXED WARNING: RISK OF HEPATITIS B VIRUS REACTIVATION IN HCV/HBV COINFECTED PATIENTS Test all patients for evidence of current or prior hepatitis B virus (HBV) infection before initiating treatment with EPCLUSA. HBV reactivation has been reported in HCV/HBV coinfected patients who were undergoing or had completed treatment with HCV direct acting antivirals (DAAs) and were not receiving HBV antiviral therapy. Some cases have resulted in fulminant hepatitis, hepatic failure, and death. Cases have been reported in patients who are HBsAg positive, in patients with serologic evidence of resolved HBV, and also in patients receiving certain immunosuppressant or chemotherapeutic agents; the risk of HBV reactivation associated with treatment with HCV DAAs may be increased in patients taking these other agents. Monitor HCV/HBV coinfected patients for hepatitis flare or HBV reactivation during HCV treatment and post-treatment follow-up. Initiate appropriate patient management for HBV infection as clinically indicated. Contraindications If EPCLUSA is used in combination with ribavirin (RBV), all contraindications, warnings and precautions, in particular pregnancy avoidance, and adverse reactions to RBV also apply. Refer to RBV prescribing information. Warnings and Precautions Serious Symptomatic Bradycardia When Coadministered with Amiodarone: Amiodarone is not recommended for use with EPCLUSA due to the risk of symptomatic bradycardia, particularly in patients also taking beta blockers or with underlying cardiac comorbidities and/or with advanced liver disease. A fatal cardiac arrest was reported in a patient taking amiodarone who was coadministered a sofosbuvir containing regimen. In patients without alternative, viable treatment options, cardiac monitoring is recommended. Patients should seek immediate medical evaluation if they develop signs or symptoms of bradycardia. Risk of Reduced Therapeutic Effect Due to Use with P-gp Inducers and/or Moderate to Strong Inducers of CYP2B6, CYP2C8 or CYP3A4 : Rifampin, St. John’s wort and carbamazepine are not recommended for use with EPCLUSA as they may significantly decrease sofosbuvir and/or velpatasvir plasma concentrations. Adverse Reactions The most common adverse reactions (≥10%, all grades) with EPCLUSA in adults and pediatric patients 6 years of age and older were headache and fatigue; and when used with RBV in adults with decompensated cirrhosis were fatigue, anemia, nausea, headache, insomnia and diarrhea. The most common adverse reactions (≥10%, grade 1 or 2) in pediatric patients less than 6 years of age were vomiting and spitting up the drug. Drug Interactions Coadministration of EPCLUSA is not recommended with topotecan due to increased concentrations of topotecan. Coadministration of EPCLUSA is not recommended with proton-pump inhibitors, phenobarbital, phenytoin, rifabutin, rifapentine, efavirenz, and tipranavir/ritonavir due to decreased concentrations of sofosbuvir and/or velpatasvir. Consult the full Prescribing Information for EPCLUSA for more information on potentially significant drug interactions, including clinical comments. Indication EPCLUSA is indicated for the treatment of adult and pediatric patients 3 years of age and older with chronic hepatitis C virus genotype 1, 2, 3, 4, 5, or 6 infection without cirrhosis or with compensated cirrhosis and in combination with ribavirin for those with decompensated cirrhosis. U.S. Important Safety Information for LIVDELZI Warnings and Precautions Fractures: Fractures occurred in 4% of LIVDELZI-treated patients compared to no placebo-treated patients. Consider the risk of fracture in the care of patients treated with LIVDELZI and monitor bone health according to current standards of care. Liver Test Abnormalities: LIVDELZI has been associated with dose-related increases in serum transaminase (AST and ALT) levels > 3 x ULN in patients receiving 50 mg and 200 mg once daily (5x and 20x higher than the recommended dosage of 10 mg once daily). Perform baseline clinical and laboratory testing when starting LIVDELZI and monitor thereafter according to routine patient management. Interrupt treatment if the liver tests (ALT, AST, total bilirubin, and/or ALP) worsen, or if the patient develops signs and symptoms of clinical hepatitis (eg, jaundice, right upper quadrant pain, eosinophilia). Consider permanent discontinuation if liver tests worsen after restarting LIVDELZI. Biliary Obstruction: Avoid use of LIVDELZI in patients with complete biliary obstruction. If biliary obstruction is suspected, interrupt LIVDELZI and treat as clinically indicated. Adverse Reactions The most common adverse reactions (≥5%) with LIVDELZI were headache (8%), abdominal pain (7%), nausea (6%), abdominal distension (6%), and dizziness (5%). Drug Interactions OAT3 Inhibitors and Strong CYP2C9 Inhibitors: Avoid coadministration with LIVDELZI due to increased LIVDELZI exposure. Rifampin: Monitor biochemical response (e.g., ALP and bilirubin) when patients initiate rifampin during LIVDELZI treatment. Coadministration may result in delayed or suboptimal biochemical response of LIVDELZI. Dual Moderate CYP2C9 and Moderate-to-Strong CYP3A4 Inhibitors and BCRP Inhibitors (eg, cyclosporine): Monitor closely for adverse effects. Concomitant administration with LIVDELZI may increase LIVDELZI exposure. CYP2C9 Poor Metabolizers Using Moderate-to-Strong CYP3A4 Inhibitors: Monitor more frequently for adverse reactions as concomitant use of a moderate-to-strong CYP3A4 inhibitor in patients who are CYP2C9 poor metabolizers may increase LIVDELZI exposure and risk of LIVDELZI adverse reactions. Bile Acid Sequestrants: Administer LIVDELZI at least 4 hours before or 4 hours after taking a bile acid sequestrant, or at as great an interval as possible. Pregnancy and Lactation Pregnancy: There are insufficient data from human pregnancies exposed to LIVDELZI to allow an assessment of a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Report pregnancies to Gilead Sciences, Inc., at 1-800-445-3235. Lactation: There are no data on the presence of LIVDELZI in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for LIVDELZI and any potential adverse effects on the breastfed infant from LIVDELZI. Indication LIVDELZI is indicated for the treatment of primary biliary cholangitis (PBC) in combination with ursodeoxycholic acid (UDCA) in adults who have an inadequate response to UDCA, or as monotherapy in patients unable to tolerate UDCA. This indication is approved under accelerated approval based on a reduction of ALP. Improvement in survival or prevention of liver decompensation events have not been demonstrated. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trial(s). Limitations of Use: Use of Livdelzi is not recommended in patients who have or develop decompensated cirrhosis (e.g., ascites, variceal bleeding, hepatic encephalopathy). About HDV HDV is considered the most aggressive or severe form of viral hepatitis, associated with more rapid progression towards liver-related death and liver cancer in people with HBV. On average, HDV progresses to cirrhosis within 5 years and to liver cancer within 10 years. Nearly 5% of people who have a chronic infection with HBV are estimated to have HDV, equating to 12-15 million people worldwide. The prevalence of HDV infection is largely underestimated due to lack of universal testing of HBV-positive individuals for HDV. About PBC PBC is a rare, chronic inflammatory liver disease primarily affecting women (1 in 1,000 women over the age of 40 or about 130,000 total people in the U.S.). PBC is characterized by impaired bile flow (known as cholestasis) and the accumulation of toxic bile acids in the liver, leading to inflammation and destruction of the bile ducts within the liver and causing increased levels of alkaline phosphatase (ALP), alanine transaminase (ALT) and gamma-glutamyl transferase (GGT), enzymes found primarily in the liver, as well as total bilirubin. The most common symptoms of PBC are pruritus and fatigue, which can be debilitating for some people. Progression of PBC is associated with an increased risk of liver-related mortality. About Gilead Sciences in Liver Disease For decades, Gilead has pioneered the way forward to improve the lives of people living with liver disease around the world. We have helped to transform hepatitis C from a chronic condition into one that can be cured for millions of people. For people living with hepatitis B or D, our focus on advancing our medicines drives hope that today’s research will turn into tomorrow’s cures. Beyond viral hepatitis, we’re working to deliver advanced treatments for people living with PBC. But our commitment doesn’t stop there. Through our ground-breaking science and collaborative partnerships, we strive to create healthier futures for everyone living with liver disease. We are committed to a future without liver disease. About Gilead Sciences Gilead Sciences, Inc. is a biopharmaceutical company that has pursued and achieved breakthroughs in medicine for more than three decades, with the goal of creating a healthier world for all people. The company is committed to advancing innovative medicines to prevent and treat life-threatening diseases, including HIV, viral hepatitis, COVID-19, cancer and inflammation. Gilead operates in more than 35 countries worldwide, with headquarters in Foster City, California. Forward-Looking Statements This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including Gilead’s ability to initiate, progress or complete clinical trials or studies within currently anticipated timelines or at all, and the possibility of unfavorable results from ongoing or additional clinical trials or studies, including those involving Epclusa, Hepcludex (bulevirtide), Livdelzi (seladelpar), cilofexor and selgantolimod (such as the ASSURE, RESPONSE, MYR301, STORC and SVR10K studies); uncertainties relating to regulatory applications and related filing and approval timelines, including the risk that the FDA and other regulatory authorities may not approve bulevirtide for the treatment of HDV, and the risk that any such approvals, if granted, may be subject to significant limitations on use or subject to withdrawal or other adverse actions by the applicable regulatory authority; the possibility that Gilead may make a strategic decision to discontinue development of investigational programs for indications that are currently under evaluation and, as a result, these programs may never be successfully commercialized for the indications currently under evaluation; and any assumptions underlying any of the foregoing. These and other risks, uncertainties and factors are described in detail in Gilead’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2024, as filed with the U.S. Securities and Exchange Commission. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. The reader is cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and is cautioned not to place undue reliance on these forward-looking statements. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation and disclaims any intent to update any such forward-looking statements. Epclusa, Hepcludex, Livdelzi, Gilead and the Gilead logo are registered trademarks of Gilead Sciences, Inc., or its related companies. For more information about Gilead, please visit the company’s website at , follow Gilead on Twitter (@Gilead Sciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000. Contacts Meaghan Smith, Media public_affairs@gilead.com Jacquie Ross, Investors investor_relations@gilead.com