Biotin

作者：钟东英 薛超然美工：何国红 罗真真排版：马超01 引言单域抗体以其分子量小、组织穿透性强、结构稳定性高等独特优势，在生物医药领域展现出广阔的应用前景。三优生物基于对天然单域抗体结构的深度解析，融合自主知识产权的AI算法，结合高通量筛选与真核表达验证技术，成功构建千亿级高等电点单域抗体库。该平台通过精准调控等电点（8.0-9.0）及系统性排除PTM位点，显著提升抗体的稳定性与成药性，为全球创新药研发提供高效、精准的单域抗体发现解决方案。02 文库背景近年来，全球单域抗体领域迎来快速发展：2020年相关市场规模已突破50亿美元，预计到2025年将增长至120亿美元以上。长期来看，到2030年，这一细分市场有望突破300亿美元，成为抗体药物中增速最快的类别之一。中国单域抗体研发的活跃度更是显著高于全球，尤其在肿瘤和罕见病治疗领域展现出领先潜力。单域抗体因其分子结构精简、组织穿透性强以及稳定性高等独特优势，正成为生物医药创新的前沿方向。与传统抗体相比，其更易实现工程化改造，可针对复杂靶点（如GPCR、离子通道）设计高亲和力药物，同时生产成本更低，有望显著加速新型疗法开发并提升其在全球范围内的可及性。然而，传统单域抗体制备技术面临成药性不足的挑战，如低等电点导致的非特异性结合、翻译后修饰（PTM）位点引发的稳定性问题等，严重限制了抗体药物的开发效率。为突破这一瓶颈，三优生物凭借前瞻性的AI驱动技术布局，于2024年成功构建并验证了千亿级高等电点单域抗体库，并将于2025年进一步扩容升级，推出超万亿高等电点单域抗体库（Super Trillion-Optimized pI Single-Domain Library，ST-OPSD）。这一突破性进展标志着三优生物在单域抗体发现领域迈入了全新阶段，其超万亿级抗体库平台将极大加速针对难成药靶点的高稳定性单域抗体药物的开发进程。03 文库组成三优生物在万亿级人源化单域抗体库的基础上持续创新，建立了千亿级高等电点单域抗体库平台。该平台采用先进的人工智能算法，对纳米抗体进行全序列生成与优化，反向筛选出具有优异成药性的候选分子。通过精准调控，文库中纳米抗体的等电点严格控制在8.0-9.0，显著提高其在体内的稳定性，减少非特异性结合。同时，系统性排除影响成药性的翻译后修饰（PTM）位点，如糖基化位点、脱酰胺及异构化等，确保抗体分子的高稳定性和可开发性。目前总库容高达1.00千亿，2025年扩容完成后，库容可达超万亿，覆盖广泛的靶点结合多样性。扩充库容后的ST-OPSD具体组成如表1所示。▼ Table 1 Composition of ST-OPSD04 文库特性01抗体先导分子等电点高通过对千亿级高等点单域抗体库筛选测序，序列分析结果表明，等电点（pI）在8.0-9.0范围内的分子占比显著提高。能够改善溶解度、降低聚集倾向，并增强在体内的稳定性，从而显著提升候选药物的生物利用度和药代动力学特性。此外，该等电点范围内的分子通常表现出更低的非特异性结合，减少了潜在的脱靶效应，进一步提高了药物的安全性和有效性。▲ Fig. 1 Comparison of 8.0-9.0 pImolecule distribution02排除PTM位点通过对千亿级高等点单域抗体库筛选测序，序列分析结果表明，候选分子不含翻译后修饰（PTM）位点。无PTM位点意味着这些分子具有更高的结构稳定性、更低的免疫原性，从而显著提升了其成药性。此外，无PTM位点也降低了生产过程中出现异质性的风险，简化了纯化和质量控制流程。▼ Table 2 Post-Translational Modifications03人源化程度高三优构建的千亿级高等电点单域抗体库具有较高的人源化程度。通过130多个单域抗体分子的人源化项目经验积累，对单域抗体的骨架区（FR区）进行人源化改造，通过文库筛选，可以直接获得人源化程度高达98%的单域抗体，无需进行额外的人源化流程，大大缩短了项目周期。04全面成药性分析千亿级高等点单域抗体库筛选服务获得的分子构建全长后，对抗体的表达量及抗体的生化理化特性进行全面分析。如表所示，包括纯度及浓度测定、一级结构分析和亲和力及亲和动力学等多个维度。▼ Table 3 Developability of Antibodiesfrom ST-OPSD05先导分子数量多针对不同难度的靶点，该平台平均可获得35个序列独特、特异性强、成药性高的先导抗体，显著加速抗体药物的开发进程。该平台不仅适用于肿瘤、自身免疫性疾病等传统治疗领域，还可拓展至双特异性抗体、抗体偶联药物（ADC）、细胞治疗等前沿方向。▲ Fig. 2 The number of leadingmolecules from different projects05 代表案例01抗BCMA单域抗体的开发基本信息：BCMA（B细胞成熟抗原）是肿瘤坏死因子受体超家族（TNFR）的重要成员，在恶性浆细胞疾病和自身免疫性疾病治疗中具有关键作用。其主要配体：BAFF（B细胞激活因子）和APRIL（增殖诱导配体）。竞争格局：BCMA靶向疗法已在临床取得显著进展并获批上市，主要包括：CAR-T细胞疗法（如Abecma, Carvykti），通过基因改造T细胞直接杀伤肿瘤；抗体偶联药物（ADC）（如Blenrep），精准递送细胞毒药物至肿瘤；以及双特异性抗体（如Tecvayli），桥接T细胞和肿瘤细胞进行杀伤。药物MOA：作用机制均为特异性结合BCMA，从而介导肿瘤细胞的清除：CAR-T细胞直接裂解肿瘤，ADC释放毒性药物诱导细胞凋亡，双抗则激活T细胞对肿瘤进行杀伤。02BCMA抗体关键结果◆ 细胞水平的结合活性分析通过三优三优千亿级高等点单域抗体库筛选获得的单域抗体候选分子大多具有较好的细胞水平结合活性。如图3展示了采用FACS分析候选抗体与huBCMA-HEK293细胞的亲和力测定结果，其中全部候选抗体的亲和力水平优于对照抗体。▲ Fig. 3. Affinity testing of antibodies◆ 阻断活性分析采用ELISA方法检测候选抗体A001、A002、A003和A004是否阻断BAFF-NFC与huBCMA-ECD-His-Biotin蛋白的结合。结果如Fig. 4所示。候选抗体A001、A002、A003和A004阻断BAFF-NFC与huBCMA-ECD-His-Biotin蛋白的结合。▲ Fig. 4 Blocking testing of antibodies06 总结展望当前，全球抗体药物市场正迎来快速发展期，2023年全球抗体药物市场规模已突破2000亿美元，其中单域抗体因其可高效靶向传统抗体难以触及的特殊表位等独特的结构优势，正成为新一代治疗药物的研发热点。作为抗体药物开发的核心引擎，单域抗体文库的构建不仅直接决定了候选分子的多样性和质量，更是突破"不可成药"靶点、实现差异化创新的战略高地，已成为全球顶尖药企和生物技术公司竞相布局的关键赛道。三优生物依托在抗体工程领域多年的技术积淀，并基于成功建立的AI-STAL平台经验，已突破高等电点单域抗体库构建的各项技术壁垒，成功完成了千亿级高等电点单域抗体库的开发和验证。展望未来，三优生物将持续发挥其平台技术优势，在2025年完成万亿级高等电点单域抗体库的构建，排除PTM位点延长抗体半衰期、加速高难度靶点和高难度表位的单域抗体发现，以及持续优化深度学习算法，从头生成具有高成药潜力的单域抗体。通过这些创新技术突破，三优生物将显著提升单域抗体药物的开发效率，大幅缩短创新抗体药物的研发周期，为全球患者提供更加系统的解决方案。Sanyou 10th Anniversary: AI-STAL - 100 Billion Optimal pI Single-Domain Antibody Library01 IntroductionSingle-domain  antibodies (sdAbs) exhibit broad therapeutic potential in biomedicine  owing to their unique advantages of small molecular size, enhanced  tissue penetration, and superior structural stability. Based on  comprehensive structural analysis of natural sdAbs, Sanyou Biotech has  constructed a 100-billion-size optimal-pI sdAb library platform  integrating proprietary AI algorithms with high-throughput screening and  eukaryotic expression validation. This platform significantly enhances  antibody stability and druggability through precise pI modulation  (8.0–9.0) and systematic elimination of PTM sites, delivering an  efficient and precise sdAb discovery solution for global innovative drug  development.02 Library BackgroundThe  single-domain antibody (sdAb) field has experienced rapid global growth  in recent years, with the market value exceeding $5 billion in 2020 and  projected to surpass $12 billion by 2025. Long-term projections  indicate this segment may reach $30 billion by 2030, positioning sdAbs  among the fastest-growing antibody therapeutics. China's sdAb R&D  activity notably outpaces global trends, demonstrating leading potential  in oncology and rare disease therapeutics. Owing to their minimized  molecular architecture, enhanced tissue penetration, and superior  stability, sdAbs are emerging as a cutting-edge modality in  biomedicines. Compared to conventional antibodies, their engineerability  enables high-affinity drug design against complex targets (e.g., GPCRs,  ion channels), while lower production costs promise accelerated  therapeutic development and improved global accessibility.However,  traditional sdAb development faces critical drug developability  challenges, including nonspecific binding due to low pI and stability  issues caused by post-translational modification (PTM) sites, which  substantially constrain antibody drug development efficiency. To  overcome these limitations, Sanyou Biotech leveraged its pioneering  AI-driven platform to successfully construct and validate a  100-billion-member optimal-pI sdAb library in 2024. The platform will be  significantly expanded in 2025 with the launch of its ST-OPSD (Super  Trillion Optimal-pI Single-Domain Library), a multi-trillion high-pI  sdAb library. This breakthrough marks Sanyou's entry into a new era of  sdAb discovery, where its trillion-scale antibody platform will  dramatically accelerate development of highly stable sdAb therapeutics  targeting difficult-to-drug targets.03 Library CompositionBuilding  upon its trillion-scale humanized sdAb library, Sanyou Bio has  innovated to establish a 100-billion-member high-pI sdAb platform. This  system employs advanced AI algorithms for de novo nanobody sequence  generation and optimization, enabling reverse screening of candidates  with superior druggability. Through precise engineering, the platform  controls nanobody pI within 8.0–9.0, significantly enhancing in vivo stability  while reducing nonspecific binding. Concurrently, it systematically  eliminates druggability-compromising post-translational modification  (PTM) sites—including glycosylation sites, deamidation, and  isomerization hotspots—ensuring high molecular stability and  developability. The current library capacity reaches 100 billion  distinct antibody sequences, with planned expansion to multi-trillion  scale in 2025. This upgraded ST-OPSD library will provide unprecedented  target-binding diversity, with detailed composition metrics presented in  Table 1.▼ Table 1 Composition of ST-OPSD04 Library Characteristics01High Isoelectric Point (pI) of Lead MoleculesSequencing  analysis of the screened high-pI sdAb library revealed a significantly  higher proportion of molecules with a pI between 8.0 and 9.0. This pI  range improves solubility, reduces aggregation propensity, and enhances in vivo stability,  thus boosting the bioavailability and pharmacokinetic properties of  drug candidates. Moreover, molecules within this pI range typically  exhibit lower non-specific binding, reducing potential off-target  effects and further enhancing drug safety and efficacy.▲ Fig. 1 Comparison of 8.0-9.0 pImolecule distribution02Exclusion of PTM SitesSequencing analysis  of the screened optimal-pI sdAb library confirmed the absence of  post-translational modification (PTM) sites in candidate molecules.  PTM-free molecules exhibit enhanced structural stability and reduced  immunogenicity, significantly improving druggability. Additionally, the  absence of PTM sites mitigates heterogeneity risks during production and  streamlines purification and quality control processes.▼ Table 2 Post-Translational Modifications03High Humanization LevelSanyou  Bio’s high-pI sdAb library features advanced humanization. Leveraging  experience from >130 sdAb humanization projects, framework regions  (FRs) were engineered to achieve up to 98% humanization directly through  library screening. This eliminates additional humanization steps,  substantially shortening project timelines.04Comprehensive Druggability ProfilingFull-length antibodies  derived from the optimal-pI sdAb library undergo multi-dimensional  characterization, including: purity and concentration quantification,  primary structure analysis, affinity and binding kinetics assessment.▼ Table 3 Developability of Antibodiesfrom ST-OPSD05High Expression YieldThe  platform delivers an average of 35 unique, highly specific, druggable  lead antibodies per target across varying difficulties. This accelerates  antibody drug development for oncology, autoimmune diseases, bispecific  antibodies, ADCs, and cell therapies.▲ Fig. 2 The number of leadingmolecules from different projects05 Case Study01Anti-BCMA sdAb DevelopmentBackground: BCMA  (B-cell maturation antigen), a TNF receptor superfamily (TNFRSF)  member, is a validated target in plasma cell malignancies and autoimmune  disorders. Key ligands: BAFF (B-cell activating factor) and APRIL (a  proliferation-inducing ligand).Competitive Landscape: Approved  BCMA-targeted therapies include: CAR-T (e.g., Abecma®, Carvykti®):  Genetically modified T-cell-mediated tumor lysis; ADC (e.g., Blenrep®):  Tumor-specific cytotoxic payload delivery; Bispecific antibody (e.g.,  Tecvayli®): T-cell engagement for tumor killing.MOA: All  modalities specifically bind BCMA to eliminate tumor cells: CAR-T  induces direct cytolysis, ADC triggers apoptosis via toxin release, and  bispecific antibodies activate T-cell cytotoxicity.02Key Results for BCMA Antibodies◆ Cell-Based Binding AffinityMost  sdAb candidates from Sanyou Bio’s optimal-pI sdAb library demonstrated  superior cell-binding affinity. FACS analysis against huBCMA-HEK293  cells revealed all candidates outperformed the control antibody (Fig. 3).▲ Fig. 3. Affinity testing of antibodies◆ Blocking ActivityELISA confirmed candidates A001-A004 effectively blocked BAFF-NFC binding to huBCMA-ECD-His-Biotin (Fig. 4).。▲ Fig. 4 Blocking testing of antibodies06 Summary and OutlookThe  global antibody drug market is expanding rapidly, surpassing $200  billion in 2023. Single-domain antibodies (sdAbs) have emerged as  pivotal next-generation therapeutics due to their unique capacity to  target cryptic epitopes inaccessible to conventional antibodies.  Strategic Value of sdAb Libraries: As the core engine for antibody  discovery, high-quality sdAb libraries offer candidate molecular  diversity, drug developability and capability to address "undruggable"  targets. This positions sdAb library development as a competitive focus  for leading biopharma companies. Leveraging decades of antibody  engineering expertise and the AI-STAL platform, Sanyou Bio has overcome  technical barriers to establish a validated high-pI sdAb library.Sanyou  Bio will leverage its platform technologies to: construct a  trillion-scale high-pI sdAb library by 2025; extend antibody half-life  through PTM site exclusion; accelerate sdAb discovery against  challenging targets/cryptic epitopes; optimize deep learning algorithms  for de novo generation of highly druggable sdAbs. These innovations will  enhance sdAb drug development efficiency and shorten R&D cycles for  novel antibody therapeutics, delivering comprehensive solutions for  global patients.推荐阅读6类分子形式之环状多肽分子产生系统解决方案轻松玩转三优oneClick+线上9大云程序6类分子形式之mRNA分子产生系统解决方案三重好礼相送暨四种抗体制备解决方案全新上线三优生物单域抗体产生系统解决方案三优生物双抗参比品网站SY-BsAb正式上线三优ADC药物研发系统解决方案三优生物oneClick+平台再次上新三优磁阵列全人源小鼠抗体发现平台重磅发布三优超万亿全人单克隆抗体产生平台盘点三优磁阵列全人源小鼠抗体发现平台隆重上线共同轻链抗体产生之超万亿共轻库盘点三优生物73种全系列双抗参比品全新上线三优生物智能超万亿分子发现平台盘点及展望十年磨一剑之三优智能百万亿分子库发展历程关于三优生物三优生物是一家以“让天下没有难做的创新生物药”为使命，以超万亿分子库和人工智能技术双驱的生物医药智能高新技术企业。公司以智能超万亿分子库为核心，打造了干湿结合、国际领先的创新生物药临床前智能化及一体化研发平台，通过“新药发现、临床前研究、智能化药物研发及前沿科学研究”等四个维度加速全球新药发现及靶标深度研究。公司总部位于中国上海，在美国、欧洲等地设有子公司，现有投产及布局的研发及GMP场地20000多平方米。公司为合作伙伴提供“差异化CRO、整合型CDO、协同型CPO、特色CRS”于一体的“创新生物药4C综合业务”。公司已建立全球营销网络，已与全球1200多家药企、生技公司等建立了良好的合作关系；已完成了1200多个新药发现及开发服务项目；已完成了50多个合作研发项目，其中9个合作项目已完成临床申报。公司已获得国家高新技术、上海市专精特新、上海市小巨人和上海“张江之星”企业认定。

2个月大的婴儿乐乐（化名）从满月开始就皮肤问题不断。她头皮屑多得像雪花，头发一撮一撮地掉，面颊泛红、脱屑，甚至发展成渗液的湿疹。妈妈起初以为只是“奶癣”，去看了皮肤科，外涂药膏、饮食调理、避免过敏原……试了各种办法，但症状反复发作，毫无起色。渐渐地，乐乐开始出现食欲差、呕吐、精神不振，甚至一度抽搐，被紧急送到医院抢救。医生在详细询问病史后，怀疑是代谢性疾病，建议尽快完善相关检查。血液代谢筛查提示：有机酸异常。进一步遗传学检测发现，乐乐存在生物素酶缺乏症（Biotinidase deficiency）相关基因突变，确诊为该罕见遗传代谢病。原来，生物素酶缺乏会导致体内无法正常利用生物素（维生素B7），从而引发皮肤损伤、神经症状、甚至危及生命。而早期表现如湿疹、脱发、呕吐等，极易被误认为是常见小病。什么是生物素酶缺乏症生物素酶缺乏症（biotinidase deficiency，BTD） 是由于生物素酶基因（biotinidase， BTD） 变异引起生物素酶活性下降，导致生物素减少，使依赖生物素的多种羧化酶的活性下降，致线粒体能量合成障碍，出现代谢性酸中毒、有机酸尿症及一系列神经与皮肤系统损害等表现。欧美生物素酶缺乏症的发病率约为1/60000，全羧化酶合成酶缺乏症的发病率约为1/87000，国内尚无统计学报告。临床表现患有BTD的婴儿出生时通常没有明显异常，症状多在出生后几周到几个月内逐渐出现。由于该病是由于体内无法有效回收生物素所致，如果在症状出现之前开始补充生物素，几乎可以完全预防症状的发生。癫痫是最常见的早期表现之一，约70%的未治疗患儿会出现癫痫发作。婴儿的癫痫发作可能不如成人典型，表现为凝视、肢体抽动、眼皮颤动或身体僵硬，通常不对抗癫痫药物起效，但在使用生物素后往往能迅速缓解。此外，患儿常表现出肌张力低下（表现为“软瘫”）、喂养困难及运动发育迟缓，如不能自主抬头或坐起。部分患儿还可能出现共济失调、嗜睡、呼吸困难等中枢神经系统受累表现，若不治疗可迅速进展至昏迷甚至死亡。除了神经系统症状，BTD也会影响感觉器官和皮肤。部分患儿可出现视力模糊或听力下降，严重者发展为失明或永久性耳聋。若早期开始生物素治疗，这些感官损害是可以避免的。在皮肤方面，常见的表现包括湿疹样皮疹、结膜炎（红眼病）及脱发，尤其以广泛性脱发更具提示性。部分患者的尿液中可检测到乳酸增高（乳酸尿）或轻微氨气味。由于代谢紊乱，部分患儿可出现肝脏或脾脏肿大。对于残留部分生物素酶活性的轻型BTD患者（尤其是儿童和成人），在健康状态下可能无症状，但在生病、发热或其他应激状态下可能会出现轻度症状，如皮疹、疲乏、癫痫或行为变化。及时补充生物素仍可逆转这些症状。总体而言，BTD是少数可通过早期干预实现完全控制甚至“治愈”的遗传代谢病之一，因此早筛查、早诊断、早治疗至关重要。诊断生物素酶缺乏症可以通过新生儿筛查诊断出来。新生儿筛查是一种特殊的筛选测试，新生儿接受这种测试是为了了解他们是否患有某些疾病。因为新生儿筛查是一种筛选试验，阳性结果并不意味着婴儿肯定患有该疾病。通常情况下，必须进行重复测试以确认诊断。出生后可以通过检测血液中的生物素酶活性来进行临床诊断。通常，这是在BTD的症状和体征变得比较清楚时进行的。在一些婴儿中，可能需要进行基因测试以确定引起BTD的特定基因变化（突变）。早在怀孕12周时就可以对子宫内的液体样本进行生物素酶活的产前检测（这包括绒毛取样和羊膜穿刺）。治疗一旦确诊BTD，应立即开始终身口服生物素治疗。生物素口服后吸收良好，安全、稳定、价格低廉，是目前治疗BTD的首选。生物素治疗通常在用药数日内即可使尿中异常有机酸代谢产物消失，伴随酸中毒、皮疹、癫痫发作等症状明显缓解，患儿全身状况改善。尽管生物素水平短期内可恢复正常，但多数中枢神经系统相关症状（如发育迟缓、运动障碍）需数月时间方能逐步恢复，部分损害如视力和听力丧失往往为不可逆。在治疗过程中，应避免食用生鸡蛋，因生鸡蛋中含有抗生物素蛋白（avidin），会与生物素结合，降低其吸收和疗效。对于症状明显或危重患儿，在治疗早期可根据病情辅助使用左卡尼汀、甲钴胺和维生素C，支持代谢和神经系统修复，同时合理控制蛋白质和葡萄糖摄入，防止进一步代谢失衡。此外，BTD为常染色体隐性遗传病，建议患儿家庭接受专业的遗传咨询。遗传咨询师可帮助家庭理解疾病的遗传机制、携带风险以及生育下一代时的相关选择，包括产前或胚胎植入前遗传检测。对于高危家庭成员，早期筛查和干预同样重要。参考资料：[1]林瑞珠,李秀珍,赵小媛,等.生物素酶缺乏症13例临床分析及随访[J].广东医学,2024,45(06):672-678.DOI:10.13820/j.cnki.gdyx.20233691.[2] Bhat MD,Bindu PS,Christopher R,et al.Novel imaging findings in two cases of biotinidase deficiency-a treatable metabolic disorder[J].Metab Brain Dis,2015,30(5):1291-1294.[3] Desai S,Ganesan K,Hegde A.Biotinidase deficiency:a reversible metabolic encephalopathy.Neuroimaging and MR spectroscopic findings in a series of four patients[J].Pediatr Radiol,2008,38(8):848-856.来源 | 梅斯医学编辑 | wanny神经系统罕见病交流群↓点击下方“阅读原文”，下载梅斯医学APP吧！