Nirmatrelvir/Ritonavir

传统认知中，病毒感染遵循“一生一次”的铁律——感染后免疫系统建立防线，抵御二次入侵。然而，新冠病毒却打破了这一规律，甚至出现“感染后更易再感染”的反常现象。2025年3月，一项发表于《公共科学图书馆·综合》（PLOS ONE）的研究揭示了这一“免疫悖论”，引发科学界与公众的广泛关注。以下从数据出发，解析新冠再感染背后的复杂机制与应对策略。一、免疫悖论：感染史为何成了“风险标签”？伊朗马什哈德医学科学大学联合国际团队，对84万人的健康数据分析发现：‌有新冠感染史者的再感染率比未感染者高出13%‌。这一结论颠覆了传统免疫学认知，暴露了新冠病毒的独特“免疫逃逸”能力。关键机制解析‌：新冠病毒（尤其是变异株）的刺突蛋白不断突变，导致抗体识别效率下降。此外，初次感染可能诱导免疫系统产生“记忆偏差”，即过度依赖对原始毒株的记忆（免疫印记效应），面对新变异株时反应迟缓，甚至误伤健康细胞（如细胞因子风暴）。这种现象类似“用旧地图导航新路线”，导致防御失效。二、谁在再感染的“风暴眼”中？高危人群画像研究进一步锁定再感染高风险群体：1️⃣ ‌男性风险比女性高24%‌：可能与职业暴露、社交活跃度及免疫应答差异有关；2️⃣ ‌18-59岁年轻人风险是60岁以上人群的1.67倍‌：年轻免疫系统或“过激反应”，非特异性抗体攻击自体细胞，反削弱保护力；3️⃣ ‌城市居民风险比农村高69%‌：密集人群与高频接触加剧传播。矛盾现象‌：60岁以上老年人尽管再感染率低，但感染后重症风险仍居高不下，需警惕“低感染率≠低威胁”。三、疫苗迷局：接种越多，风险越大？研究显示，接种3剂及以上疫苗者的再感染风险比未接种者高50%。这一结果看似矛盾，但背后存在科学解释：免疫印记效应‌：多次接种原始毒株疫苗，可能导致免疫系统对新变异株反应迟钝；抗体依赖性增强（ADE）假说‌：特定情况下，抗体可能协助病毒侵入细胞，但此机制尚未被完全证实。需明确的是‌：疫苗的核心价值在于‌大幅降低重症率和死亡率‌。研究未否认疫苗对重症的防护作用，且结果可能受病毒流行阶段、变异株类型等因素影响。四、反常识发现：基础疾病患者为何更安全？患有高血压、糖尿病等基础疾病的人群，再感染风险比健康人群低5%。研究者分析：行为因素‌：此类人群防护意识更强，如坚持佩戴口罩、减少聚集；医疗干预‌：定期就医便于早期发现感染，及时用药阻断病毒复制。这一现象印证：‌科学的个体防护可显著弥补生理脆弱性‌。五、科学应对策略：常态化防疫的核心基于研究启示，建议从三方面构建健康防线：1️⃣ ‌精准防护不松懈‌高危人群（老年人、免疫缺陷者）在公共场所坚持佩戴口罩；注重手卫生，避免触摸眼鼻口；定期室内通风，降低气溶胶传播风险。2️⃣ ‌健康监测与及时干预‌出现发热、咽痛等症状时，立即抗原检测；确诊后尽早使用抗病毒药物（如Paxlovid），减少重症转化。3️⃣ ‌免疫力“动态升级”‌均衡营养（补充维生素D、锌等免疫相关营养素）；规律运动（每周150分钟中等强度活动）；管理慢性病，避免免疫系统过载（口服胸腺肽、葡聚糖）。结语新冠的“免疫悖论”揭示了病毒与人类免疫系统博弈的复杂性。既往感染不是护身符，疫苗也非万能盾牌。面对不断变异的病毒，唯有依托科学认知、动态调整防护策略，才能在这场持久战中掌握主动权。正如研究者所言：“真正的免疫力，来自于对风险的清醒认知与持续的自我保护进化。”免责申明：文章来源网络仅供分享，不构成任何临床诊断建议，我们尊重原创，也注重分享，图文素材来源于网络，如有违规或侵权，请及时联系我们会立即做出删除

Met Target Enrollment for RSVHR, a Phase 2 Study of Zelicapavir in High-Risk Adults Infected with Respiratory Syncytial Virus (RSV); On Track to Report Topline Data in Late 3Q 2025 STAT6 Program Progressing with Plans to Select a Development Candidate in 2H 2025 IND Enabling Studies of KIT Inhibitor EPS-1421 Ongoing Cash and Marketable Securities Totaling $193.4 Million at March 31, 2025 , Further Strengthened by a $33.8 Million Federal Income Tax Refund Received in April 2025 WATERTOWN, Mass. --(BUSINESS WIRE)--May 12, 2025-- Enanta Pharmaceuticals, Inc. (NASDAQ:ENTA), a clinical-stage biotechnology company dedicated to creating small molecule drugs for viral infections and immunological diseases, today reported financial results for its fiscal second quarter ended March 31, 2025 . “Throughout the fiscal second quarter, Enanta remained squarely focused on executing across our virology and immunology pipeline. We are thrilled to have enrolled our target of 180 patients in RSVHR, a Phase 2 study of zelicapavir in high-risk adults infected with RSV, and plan to complete enrollment in late May to capture the remainder of the current Northern Hemisphere RSV season. We remain on track to report topline data late next quarter. With two differentiated mechanisms of action, N- and L-protein inhibition, Enanta has the most comprehensive RSV antiviral portfolio in development, and we will evaluate potential partnership opportunities to bring these therapeutics to patients,” said Jay. R. Luly , Ph.D., President and Chief Executive Officer at Enanta Pharmaceuticals . Dr. Luly continued, “We are also pleased with the progress we have made in advancing our immunology programs that target key drivers of type 2 inflammation. We expect to select a lead development candidate for our oral STAT6 inhibitor program in the second half of this year, with an initial indication in atopic dermatitis and future expansion opportunities in asthma and other diseases. Additionally, we are continuing to advance EPS-1421, the lead development candidate in our KIT inhibitor program, with the goal of developing a best-in-disease, oral treatment for chronic spontaneous urticaria and other mast cell driven diseases. We look forward to continuing to expand our immunology portfolio with the announcement of a third program this year. With a strong cash position and a disciplined approach to capital allocation, we are well-suited to execute across our pipeline of oral therapeutics in development for virology and immunology indications.” Fiscal Second Quarter Ended March 31, 2025 Financial Results Total revenue for the three months ended March 31, 2025 was $14.9 million and consisted of royalty revenue from worldwide net sales of AbbVie’s hepatitis C virus (HCV) regimen MAVYRET®/MAVIRET® (glecaprevir/pibrentasvir), compared to $17.1 million for the three months ended March 31, 2024 . A portion (54.5%) of Enanta’s ongoing royalty revenue from AbbVie’s net sales of MAVYRET®/MAVIRET® is paid to OMERS, one of Canada’s largest defined benefit pension plans, pursuant to a royalty sale transaction affecting royalties earned after June 2023 . For financial reporting purposes, the transaction was treated as debt, with the upfront purchase payment of $200.0 million recorded as a liability. Each quarter, Enanta records 100% of the royalty earned as revenue and then amortizes the debt liability proportionally as 54.5% of the cash royalty payments are paid to OMERS through June 30, 2032 , subject to a cap of 1.42 times the purchase price, after which point 100% of the cash royalty payments will be retained by Enanta. Interest expense from the royalty sale was $1.7 million for the three months ended March 31, 2025 , as compared to $2.6 million for the same period ended March 31, 2024 . Research and development expenses totaled $28.1 million for the three months ended March 31, 2025 , compared to $35.6 million for the three months ended March 31, 2024 . The decrease was primarily due to a decrease in expenses as a result of the timing of clinical trials in the Company’s RSV program. General and administrative expenses totaled $11.4 million for the three months ended March 31, 2025 , compared to $14.2 million for the three months ended March 31, 2024 . The decrease was primarily due to a decrease in legal expenses related to the Company’s patent infringement lawsuit against Pfizer. Interest and investment income, net, totaled $2.3 million for the three months ended March 31, 2025 , compared to $3.8 million for the three months ended March 31, 2024 . The decrease was due to lower cash and investment balances year-over-year. Enanta recorded an income tax benefit of $1.3 million for the three months ended March 31, 2025 primarily due to an additional federal income tax refund of $0.9 million . Enanta recorded an income tax benefit of $0.4 million for the three months ended March 31, 2024 related to interest earned on the federal income tax refund. The federal income tax refund of $33.8 million , including interest, was received in April 2025 . Net loss for the three months ended March 31, 2025 was $22.6 million , or a loss of $1.06 per diluted common share, compared to a net loss of $31.2 million , or a loss of $1.47 per diluted common share, for the corresponding period in 2024. Enanta’s cash, cash equivalents and short-term marketable securities totaled $193.4 million at March 31, 2025 . Enanta expects that its current cash, cash equivalents and marketable securities, as well as its retained portion of future royalty revenue, together with a $33.8 million federal income tax refund received in April 2025 , will be sufficient to meet the anticipated cash requirements of its existing business and development programs into fiscal 2028. Virology Enanta’s virology pipeline is focused on developing oral antiviral treatments for serious infections, including multiple clinical-stage programs for the treatment of RSV. Enanta has the leading RSV therapeutic portfolio, consisting of zelicapavir and EDP-323, both in Phase 2 development for RSV infection. The Company will evaluate potential partnership opportunities to further develop its RSV assets. Zelicapavir, a potent, oral N-protein inhibitor, which has Fast Track designation from the U.S. Food and Drug Administration , is currently being evaluated in RSVHR, a Phase 2b, randomized, double-blind, placebo-controlled study in adults with RSV infection who are at high-risk of complications. This includes patients over age 65 years and/or those with congestive heart failure, chronic obstructive pulmonary disease or asthma. Target enrollment of 180 patients in RSVHR has been met. Enanta is continuing enrollment through late May to capture the remainder of the Northern Hemisphere RSV season. The Company will complete enrollment this month, with topline data expected late next quarter. Zelicapavir previously demonstrated positive data in a Phase 2 human challenge study and in a Phase 2 study of pediatric patients. Enanta’s second RSV asset, EDP-323, is a potent, oral L-protein inhibitor, which also has Fast Track designation. In a human challenge study, EDP-323 achieved highly statistically significant reductions in both viral load and clinical symptoms compared to placebo, as well as a favorable safety and tolerability profile. EDP-323 can be used alone or in combination with other agents, such as zelicapavir, to potentially broaden the treatment window or addressable patient populations. In March, Enanta presented data from its RSV portfolio at the 13th International RSV Symposium (RSV2025). Results from a Phase 2 human challenge study of EDP-323 were highlighted in an oral presentation, while data from the Phase 2 study of zelicapavir in pediatric patients were presented in a late breaker poster. An additional poster highlighted distinctions among fusion, N-, and L-protein inhibitors with respect to preclinical antiviral effect and resistance profiles, while a final poster detailed PK and PK/PD results from the EDP-323 Phase 2 human challenge study. Copies of these presentations can be found on the Company’s website. Zelicapavir, a potent, oral N-protein inhibitor, which has Fast Track designation from the U.S. Food and Drug Administration , is currently being evaluated in RSVHR, a Phase 2b, randomized, double-blind, placebo-controlled study in adults with RSV infection who are at high-risk of complications. This includes patients over age 65 years and/or those with congestive heart failure, chronic obstructive pulmonary disease or asthma. Target enrollment of 180 patients in RSVHR has been met. Enanta is continuing enrollment through late May to capture the remainder of the Northern Hemisphere RSV season. The Company will complete enrollment this month, with topline data expected late next quarter. Zelicapavir previously demonstrated positive data in a Phase 2 human challenge study and in a Phase 2 study of pediatric patients. Enanta’s second RSV asset, EDP-323, is a potent, oral L-protein inhibitor, which also has Fast Track designation. In a human challenge study, EDP-323 achieved highly statistically significant reductions in both viral load and clinical symptoms compared to placebo, as well as a favorable safety and tolerability profile. EDP-323 can be used alone or in combination with other agents, such as zelicapavir, to potentially broaden the treatment window or addressable patient populations. In March, Enanta presented data from its RSV portfolio at the 13th International RSV Symposium (RSV2025). Results from a Phase 2 human challenge study of EDP-323 were highlighted in an oral presentation, while data from the Phase 2 study of zelicapavir in pediatric patients were presented in a late breaker poster. An additional poster highlighted distinctions among fusion, N-, and L-protein inhibitors with respect to preclinical antiviral effect and resistance profiles, while a final poster detailed PK and PK/PD results from the EDP-323 Phase 2 human challenge study. Copies of these presentations can be found on the Company’s website. Immunology Enanta’s immunology pipeline is focused on designing and developing highly potent and selective oral inhibitors for the treatment of inflammatory diseases, by targeting key drivers of the type 2 immune response. KIT inhibitors Enanta’s lead development candidate, EPS-1421, is a novel, potent and selective oral inhibitor of KIT, a receptor tyrosine kinase and central regulator of mast cell development and activation. The Company is currently conducting scale-up activities and IND enabling studies. STAT6 Inhibitors Enanta’s second immunology program is targeting STAT6, the transcription factor responsible for IL-4/IL-13 signaling, which drives a type 2 dominant phenotype and downstream inflammation. Type 2 dysregulation is responsible for multiple allergic and autoimmune diseases. Enanta’s prototype oral STAT6 inhibitors exhibit nanomolar inhibition in biochemical and cellular assays, with good intrinsic permeability and oral bioavailability. In addition, inhibition of IL-4 induced phosphorylation of STAT6 in human peripheral blood mononuclear cells (hPBMC) and prevention of TARC production, a STAT6 biomarker of type 2 inflammation, have been observed. Further, the STAT6 prototypes are highly selective, with no inhibition of other STATs in hPBMCs and more than 1000-fold biochemical selectivity over other STATs, demonstrating significantly more selectivity than JAK inhibitors. In a mouse model, a prototype oral inhibitor resulted in rapid and complete inhibition of IL-4 induced phosphorylated STAT6 after a single dose, demonstrating in vivo target engagement. The Company plans to select a STAT6 development candidate in the second half of 2025. Enanta plans to expand its immunology pipeline with the introduction of a third program in 2025. KIT inhibitors Enanta’s lead development candidate, EPS-1421, is a novel, potent and selective oral inhibitor of KIT, a receptor tyrosine kinase and central regulator of mast cell development and activation. The Company is currently conducting scale-up activities and IND enabling studies. STAT6 Inhibitors Enanta’s second immunology program is targeting STAT6, the transcription factor responsible for IL-4/IL-13 signaling, which drives a type 2 dominant phenotype and downstream inflammation. Type 2 dysregulation is responsible for multiple allergic and autoimmune diseases. Enanta’s prototype oral STAT6 inhibitors exhibit nanomolar inhibition in biochemical and cellular assays, with good intrinsic permeability and oral bioavailability. In addition, inhibition of IL-4 induced phosphorylation of STAT6 in human peripheral blood mononuclear cells (hPBMC) and prevention of TARC production, a STAT6 biomarker of type 2 inflammation, have been observed. Further, the STAT6 prototypes are highly selective, with no inhibition of other STATs in hPBMCs and more than 1000-fold biochemical selectivity over other STATs, demonstrating significantly more selectivity than JAK inhibitors. In a mouse model, a prototype oral inhibitor resulted in rapid and complete inhibition of IL-4 induced phosphorylated STAT6 after a single dose, demonstrating in vivo target engagement. The Company plans to select a STAT6 development candidate in the second half of 2025. Enanta plans to expand its immunology pipeline with the introduction of a third program in 2025. Enanta’s lead development candidate, EPS-1421, is a novel, potent and selective oral inhibitor of KIT, a receptor tyrosine kinase and central regulator of mast cell development and activation. The Company is currently conducting scale-up activities and IND enabling studies. Enanta’s second immunology program is targeting STAT6, the transcription factor responsible for IL-4/IL-13 signaling, which drives a type 2 dominant phenotype and downstream inflammation. Type 2 dysregulation is responsible for multiple allergic and autoimmune diseases. Enanta’s prototype oral STAT6 inhibitors exhibit nanomolar inhibition in biochemical and cellular assays, with good intrinsic permeability and oral bioavailability. In addition, inhibition of IL-4 induced phosphorylation of STAT6 in human peripheral blood mononuclear cells (hPBMC) and prevention of TARC production, a STAT6 biomarker of type 2 inflammation, have been observed. Further, the STAT6 prototypes are highly selective, with no inhibition of other STATs in hPBMCs and more than 1000-fold biochemical selectivity over other STATs, demonstrating significantly more selectivity than JAK inhibitors. In a mouse model, a prototype oral inhibitor resulted in rapid and complete inhibition of IL-4 induced phosphorylated STAT6 after a single dose, demonstrating in vivo target engagement. The Company plans to select a STAT6 development candidate in the second half of 2025. Corporate In April 2025 , the Company received a $33.8 million federal income tax refund. On March 21, 2025 , Enanta filed an opening brief with the United States Court of Appeals for the Federal Circuit . The original case was filed in the United States District Court for the District of Massachusetts on June 21, 2022 , against Pfizer, Inc. seeking damages for infringement of U.S. Patent No. 11,358,953 (the ’953 Patent) in the manufacture, use and sale of Pfizer’s COVID-19 antiviral, Paxlovid™ (nirmatrelvir tablets; ritonavir tablets). Enanta plans to issue its fiscal third quarter financial results press release on August 11, 2025 . About Enanta Pharmaceuticals, Inc. Enanta is using its robust, chemistry-driven approach and drug discovery capabilities to become a leader in the discovery and development of small molecule drugs with an emphasis on indications in virology and immunology. Enanta’s clinical programs are currently focused on respiratory syncytial virus (RSV) and its earlier-stage immunology pipeline aims to develop treatments for inflammatory diseases by targeting key drivers of the type 2 immune response, including KIT and STAT6 inhibition. Glecaprevir, a protease inhibitor discovered by Enanta, is part of one of the leading treatment regimens for curing chronic hepatitis c virus (HCV) infection and is sold by AbbVie in numerous countries under the tradenames MAVYRET® ( U.S. ) and MAVIRET® (ex- U.S. ) (glecaprevir/pibrentasvir). A portion of Enanta’s royalties from HCV products developed under its collaboration with AbbVie contribute ongoing funding to Enanta’s operations. Please visit www.enanta.com for more information. Forward Looking Statements This press release contains forward-looking statements, including statements with respect to the timeline and prospects for advancement of Enanta’s clinical programs in RSV and its preclinical immunology programs, including its programs targeting KIT and STAT6 inhibition. Statements that are not historical facts are based on management’s current expectations, estimates, forecasts and projections about Enanta’s business and the industry in which it operates and management’s beliefs and assumptions. The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements. Important factors and risks that may affect actual results include: the impact of development, regulatory and marketing efforts of others with respect to vaccines and competitive treatments for RSV; the discovery and development risks of Enanta’s programs in virology and immunology; Enanta’s lack of clinical development experience; Enanta’s ability to partner its RSV or other programs; Enanta’s need to attract and retain senior management and key research and development personnel; Enanta’s need to obtain and maintain patent protection for its product candidates and avoid potential infringement of the intellectual property rights of others; and other risk factors described or referred to in “Risk Factors” in Enanta’s Form 10-K for the fiscal year-ended September 30, 2024 , and any other periodic reports filed more recently with the Securities and Exchange Commission . Enanta cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Enanta undertakes no obligation to update or revise these statements, except as may be required by law. Tables to Follow UNAUDITED (in thousands, except per share amounts) Three Months Ended Six Months Ended March 31 , March 31 , 2025 2024 2025 2024 $ 14,926 $ 17,054 $ 31,885 $ 35,057 28,065 35,585 55,721 71,956 11,388 14,235 24,234 30,753 39,453 49,820 79,955 102,709 (24,527 ) (32,766 ) (48,070 ) (67,652 ) (1,714 ) (2,563 ) (3,676 ) (6,004 ) 2,292 3,809 5,091 8,107 (23,949 ) (31,520 ) (46,655 ) (65,549 ) 1,305 363 1,721 985 $ (22,644 ) $ (31,157 ) $ (44,934 ) $ (64,564 ) $ (1.06 ) $ (1.47 ) $ (2.11 ) $ (3.06 ) $ (1.06 ) $ (1.47 ) $ (2.11 ) $ (3.06 ) 21,355 21,167 21,295 21,128 21,355 21,167 21,295 21,128 March 31 , September 30 , 2025 2024 $ 60,213 $ 37,233 133,162 210,953 6,792 6,646 8,857 12,413 33,836 31,999 - 608 242,860 299,852 37,572 32,688 39,103 40,658 3,360 3,360 98 94 $ 322,993 $ 376,652 $ 4,756 $ 8,002 8,314 13,547 30,681 34,462 2,196 1,524 45,947 57,535 125,379 134,779 56,536 53,943 1,350 1,350 243 231 229,455 247,838 93,538 128,814 $ 322,993 $ 376,652 View source version on businesswire.com: https://www.businesswire.com/news/home/20250512968099/en/ Media and Investors: Jennifer Viera jviera@enanta.com Source: Enanta Pharmaceuticals, Inc.