Vobarilizumab

JERUSALEM, July 2, 2024 /PRNewswire/ -- Scinai Immunotherapeutics Ltd. (Nasdaq: SCNI) ("Scinai", or the "Company"), a biopharmaceutical company focused on developing inflammation and immunology (I&I) biological products and on providing CDMO services through its Scinai Bioservices business unit, today published its financial results for the quarter ended March 31, 2024, and provided a business update. Business Update & Recent Highlights Financing In support of the Company's strategic pivot, on January 3, 2024, we raised $1.69 million in gross proceeds from the exercise of certain of our outstanding warrants and the issuance of new warrants. H.C. Wainwright & Co. acted as exclusive placement agent in connection with the offering. Nasdaq Compliance and Conversion of EIB Loan into Equity On June 7, 2024 the Company announced that on June 5, 2024, it received formal notification from the Listing Qualification Department (the "Staff") of the Nasdaq Stock Market ("Nasdaq") that the Company had regained compliance with the minimum $1.00 bid price requirement set forth in Nasdaq Listing Rule 5550(a)(2) (the "Rule"). In the notification provided by the Staff on June 5, 2024, the Staff stated that the Company remains non-compliant with the equity requirement in Listing Rule 5550(b)(1), or any of the alternative requirements under Listing Rule 5550(b), and accordingly the Company presented its plan to get back into compliance with the equity requirement with the Nasdaq Hearing Panel on June 18, 2024. The Plan presented to the panel included a debt-to-equity loan restructuring deal the Company is working on with its lender, the European Investment Bank (the "EIB"). On June 13, 2024 the Company announced that it received a letter of Intent from the EIB. This LoI outlined specific indicative terms for converting the EIB's loan into equity. The Company expects to receive a binding term sheet in July and have the financial contract with EIB fully amended by the end of August. Based on the above plan, the Company requested from the Nasdaq Hearing Panel an extension of the deadline for regaining compliance with the equity requirement. The Company expects to receive the decision of the Hearing Panel in the coming weeks. CDMO business unit In the first six months of 2024 we received CDMO work orders valued at approximately $500K, and we are in advanced contract discussions with several other potential clients. We maintain confidence in our sales guidance for 2024 of $1.25 million in expected revenues. As our CDMO unit is new and we are in a rapid growth stage, acquiring new clients and building our reputation and brand awareness of our CDMO services, we expect revenues from the CDMO business to increase materially in the coming years. This is also coupled with growing demand for boutique CDMO services from early-stage biotech companies looking for fast project onset at competitive pricing without compromising on meeting the most stringent scientific and quality standards. In addition, in 2024 we have been pursuing extensive targeted marketing activities, including online advertisements, direct outreach campaigns and participation in major pharmaceutical conferences, such as BIO Europe Spring in Barcelona (March 2024), and the BioMed Israel conference in Tel Aviv, Israel (May 2024), at which we marketed our CDMO services and met potential partners for our R&D pipeline and potential investors. Our CDMO unit is currently focused both on executing drug development projects for our clients and on validating our processes and facilities to be ready for cGMP inspection by the Israeli Ministry of Health. In June, we held a first of its kind, hands on aseptic processing course at our facility in Jerusalem in collaboration with key figures in the industry including Ms. Rachel Shimonovitz, Head of GMP inspectorate of the Israeli Ministry of Health, and ADRES Int'l Biotech, a leading Israeli regulatory and quality consulting services firm. The course attracted many senior role holders from the Israeli biotech industry who came to our facility for this two-day education and training course. Pipeline Development We are aggressively advancing the NanoAb preclinical development. At the end of April 2024, we concluded an in-vivo proof of concept animal study in collaboration with Prof. Amos Gilhar, a world-renowned dermatologist of the prestigious Technion Israel Institute of Technology. The results look promising and corroborate our aspiration for the development of a novel, local biologics therapeutic for the treatment of patients suffering from plaque psoriasis. On June 4, 2024, we met for a scientific advisory meeting with the Paul Erlich Institute (the PEI) of Germany, the scientific advice of which is considered acceptable guidance for IMPD filing with the European Medicines Agency (EMA) and is also considered the European comparable to a pre-IND meeting with the FDA in the U.S. We expect their final minutes of the meeting in the coming couple of weeks. Upon guidance from the PEI, we expect to commence preparations for a pre-clinical toxicology study before commencing a first-in-human clinical trial of our anti-IL NanoAbs for the treatment of plaque psoriasis in 2025. Additional NanoAbs for treatment of additional autoimmune diseases, such as asthma, atopic dermatitis and wet AMD, have been discovered and characterized at Max Planck and University Medical Center Göttingen as part of their research collaboration agreement with Scinai. Scinai holds exclusive options for exclusive licenses at pre-agreed financial terms for each of the resulting NanoAbs. We are pursuing a strategic partnership for both our COVID-19 self-administered inhaled NanoAb, which demonstrated highly promising in vivo results in animals as both a therapeutic and prophylactic treatment, and our anti-IL-17 nanoAb for the treatment of plaque psoriasis and other potential indications. Q1 2024 Financial Summary R&D expenses for the three months ended March 31, 2024, amounted to $1,568 thousands, compared to $1,995 thousands for the three months ended March 31, 2023. The decrease was primarily due to a reduction in salaries and reduced use of subcontractors. Marketing, general and administrative expenses for the three months ended March 31, 2024, amounted to $484 thousands, compared to $1,191 thousands for the three months ended March 31, 2023. The decrease was primarily due to a reduction in each of salaries, share-based compensation and professional services. Financial income for the three months ended March 31, 2024, amounted to $231 thousands compared to $329 thousands for the three months ended March 31, 2023. Net loss for the three months ended March 31, 2024, was $2,159 thousands compared to net loss of $3,515 thousands for the three months ended March 31, 2023. As of March 31, 2024, Scinai had cash and cash equivalents and short-term deposits of $4,826 thousands compared to $4,870 thousands as of March 31, 2023. About Scinai Immunotherapeutics Scinai Immunotherapeutics Ltd. (Nasdaq: SCNI) is a biopharmaceutical company with two complementary business units, one focused on in-house development of inflammation and immunology (I&I) biological therapeutic products beginning with an innovative, de-risked pipeline of nanosized VHH antibodies (NanoAbs) targeting diseases with large unmet medical needs, and the other a boutique CDMO providing biological drug development, analytical methods development, clinical cGMP manufacturing, and pre-clinical and clinical trial design and execution services for early stage biotech drug development projects. Company website: . Company Contacts Investor Relations | +972 8 930 2529 | ir@scinai.com Business Development | +972 8 930 2529 | bd@scinai.com Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Litigation Reform Act of 1995. Words such as "expect," "believe," "intend," "plan," "continue," "may," "will," "anticipate," and similar expressions are intended to identify forward-looking statements. All statements, other than statements of historical facts, are forward-looking statements. Examples of such statements include, but are not limited to, execution of a binding term sheet providing for revised terms of the Finance Contract with EIB, the accounting impact of execution of such revised terms and the ability of the Company to regain and remain compliant with the continued listing standards of Nasdaq, the potential of Scinai's NanoAb program, expected revenues of Scinai's CDMO business and timing of pre-clinical and clinical studies of the Company's anti-IL NanoAbs for the treatment of plaque psoriasis and their results. These forward-looking statements reflect management's current views with respect to certain current and future events and are subject to various risks, uncertainties and assumptions that could cause the results to differ materially from those expected by the management of Scinai Immunotherapeutics Ltd. Risks and uncertainties include, but are not limited to, the risk that the Company will not execute a binding term sheet with the EIB providing for revised terms of the Finance Contract with EIB and the risk that execution of such binding term sheet will not resolve the deficiency notice of Nasdaq with respect to the Company's shareholders' equity; the risk that the Company will otherwise be unable to regain compliance and remain compliant with the continued listing requirements of Nasdaq; lower than anticipated revenues of Scinai's CDMO business in 2024 and thereafter, failure to sign agreements with other potential clients of the CDMO business; a delay in the commencement and results of pre-clinical and clinical studies, the risk of delay in, Scinai's inability to conduct, or the unsuccessful results of, its research and development activities, including the contemplated in-vivo studies and a clinical trial; the risk that Scinai will not be successful in expanding its CDMO business or in-license other NanoAbs; the risk that Scinai may not be able to secure additional capital on attractive terms, if at all; the risk that the therapeutic and commercial potential of NanoAbs will not be met or that Scinai will not be successful in bringing the NanoAbs towards commercialization; the risk of a delay in the preclinical and clinical trials data for NanoAbs, if any; the risk that our business strategy may not be successful; the risk that the European Investment Bank (EIB) may accelerate the financial facility under its finance contract with Scinai; Scinai's ability to acquire rights to additional product opportunities; Scinai's ability to enter into collaborations on terms acceptable to Scinai or at all; timing of receipt of regulatory approval of Scinai's manufacturing facility in Jerusalem, if at all or when required; the risk that the manufacturing facility will not be able to be used for a wide variety of applications and other vaccine and treatment technologies; and the risk that drug development involves a lengthy and expensive process with uncertain outcomes. More detailed information about the risks and uncertainties affecting the Company is contained under the heading "Risk Factors" in the Company's Annual Report on Form 20-F filed with the Securities and Exchange Commission ("SEC") on May 15, 2024, and the Company's subsequent filings with the SEC. Scinai undertakes no obligation to revise or update any forward-looking statement for any reason. Logo - Company Codes: NASDAQ-NMS:SCNI

背景当前市售的44种抗体相关产品在2013年全球的销售额约为750亿美金。治疗性抗体已经成为多种癌症、自身免疫、炎症和其他疾病患者的主要治疗选择。但是，抗体治疗本身也有局限性，比如接受抗体治疗的患者可能产生抗药性或对治疗没有反应。癌或和其他疾病往往是多方面原因引起的，并由多个信号通路参与病理的发生。仅采用单靶向的抗体治疗似乎不足以破坏癌症细胞。双特异性抗体（BsAbs）在过去的几十年中已经被认为是有潜力的癌症治疗药，但是直到最近才开始出现好的成果。BsAbs具有以下几个优势：能够使特异免疫细胞重定向到肿瘤细胞从而促进对肿瘤的杀伤作用可以同时阻断两个导致病理发生的不同通路可以与两个不同细胞表面抗原相互作用增强结合特异性但是产品不稳定、低表达、免疫原性等生产相关问题一直阻碍着BsAbs的发展。新型的BsAbs比较稳定、易生产和低免疫原性。目前，有三十多个BsAbs在临床报批阶段，其中有两种药已经被批准上市。目前主要通过三种方法生产BsAbs：（1）细胞杂交瘤技术（2）化学偶联方法（3）重组DNA方法这些方法改变了BsAbs的发展，设计出很多不同的新型BsAbs去满足不同应用（图1）。图1 形成双特异性抗体的不同方法BsAbs类型BsAbs可以分为两类: IgG样分子和非IgG样分子（图2）。IgG样BsAbs保留着Fc结构域介导的效应功能如ADCC、CDC、ADCP。Fc结构域的保留还有易于纯化并提高抗体的溶解性和稳定性。由于分子结构较大和FcRn介导的再循环使IgG样BsAbs具有较长的半衰期。同样由于分子结构小，使得非IgG样BsAbs组织穿透力增强。图2 双特异性抗体的分子类型抗体样BsAbs1. 杂交瘤细胞融合型BsAbs杂交瘤融合技术基于不同杂交瘤的融合。抗体的重链和轻链的随机配对产生了BsAbs，但是也会产生没有功能的BsAbs（图3）。卡妥索单抗（Catumaxomab）是第一个被批准的大鼠/小鼠杂交瘤细胞表达的BsAbs（图4）。图3 杂交瘤细胞融合技术生长双特异性抗体图4 第一个上市的双特异性抗体-卡妥索单抗作用机制示意图2. Knobs-into-holes具有Fc结构域的BsAbs可能会形成同源二聚体和其他错配的杂质。纽扣型BsAbs的方法通过在一种抗体的CH3结构域设计一个较大的氨基酸作为“knob”和在另一种抗体的CH3结构域设计一个“hole”来解决错配问题。为了解决轻链错配问题，有以下几种方案：（a）设计含有普通轻链的BsAb，但是结合特异性受限，并不适用所有BsAb。（b）在不同的细菌中分别表达含有“knob”和“hole”的抗体，但是在细菌中表达会缺少关键的糖基化修饰，会影响抗体的效应功能（图5）。图5 在细菌中通过knobs-into-holes方法生成双特异性抗体（c）结合CrossMab和Knobs-into-holes方法能够减少错配。在CrossMab中，重链CH1结构域与轻链CL结构域互换引起轻链的正确配对。结合CrossMab和Knobs-into-holes方法，罗氏开发特异靶向Ang-2和VEGFA的交叉BsAbs A2V。（d）VH-VL和CH1-CL接触域引入一些突变。这些突变可以使重链优先与轻链配对。缺点是需要在抗体的保守区进行大范围的突变。3. 双可变结构域Ig（ Dual-Variable Domain Immunoglobulin, DVD-Ig）将两个抗体的可变结构域串联在一起形成双特异IgG样分子。DVD-Ig的每个Fab结合两个靶标。这个技术可以避免不同的重链或轻链的错配，同时提高生产的重复性、产量和稳定性，而且含有Fc结构域便于纯化。但是，可变区内部的亲和结合力有降低的潜在风险。4. IgG-scFvIgG-scFV是将scFv或单链可变区连接到轻链或重链的末端，这类抗体也属于DVD-Igs。5. 二合一或双功能Fab（Dual Action Fab, DAF）抗体DAF抗体有双抗原结合位点。抗体本身能够结合的靶抗原为第一个抗原，在抗原结合区引入突变可以识别第二个抗原。对抗原结合位点进行编辑促进高双亲合力（图6）。但是，二合一抗体不能同时结合两个不同的抗原。图6 二合一抗体通过引入突变能够识别不同类型的抗原6. 半分子交换抗体在血清中，人源IgG4能够交换半个分子，产生IgG4 bsAbs，这种途径称为“半分子交换”。IgG1的CH3结构域引入点突变后，在特定的条件下IgG1通过半分子交换形成BsAbs（图7），这项技术也应用于人IgG2和IgG3。这是方法能够在短期内产生很多种BsAbs，并且通过半分子交换产生的BsAbs是天然的形式，具有较低的免疫源性。图7 IgG1的CH3结构域引入突变后通过半分子交换形成BsAbs7. κλ抗体在一个细胞中能够同时表达一个重链和两个不同的结合特异性的轻链（κ和λ），能够产生具有与同一种重链配对的κ和λ轻链的BsAbs（图8），然后用高选择性的亲合树脂进行纯化（图9）。κλ抗体有很多优势：第一，BsAbs保留完整人IgG形式，没有任何修饰；第二，方便从抗体混合物中纯化BsAbs，第三，能够生产工业级的BsAbs；第四，纯化平台可以适用于任何κλ抗体，可以同时开发不同的BsAbs。图8 形成κλ抗体的流程示意图步骤1通过噬菌体文库筛出相应的κ和λ轻链，步骤3在同一个细胞中表达κ轻链、λ轻链和重链。图9 亲和层析快速从抗体混合物中纯化纯化出BsAbs非抗体样BsAbs1. ScFv型BsAbsScFv由VL结构域和VH结构域构成，VL结构域和VH结构域是抗原结合的基本结构。根据连接肽长度、抗体长度和外部因素可以产生二聚、三聚或四聚ScFvs（图10）。与常规IgG分子相比，ScFvs具有高肿瘤特异性格组织渗透性。图10 不同长度的连接肽产生不同类型的BsAbs（a）串联scFvs两个ScFvs通过易弯曲的连接肽（如Gly-Ser重复序列）以串联的方式连接在一起。短连接肽可以防止链内VH结构域和VL结构域配对。易弯曲的长连接肽允许抗原结合位点自由旋转，受欢迎的双特异的T细胞衔接抗体（BiTE）技术以此结构基础设计的。（b）双价特异抗体双价双特异抗体的不同抗体的可变区结构域通过两条连接肽连接。第一个抗体的VH结构域连接第二个抗体的VL结构域，两个连接肽可以提高双价抗体的稳定性，但是两个连接肽会限制抗原结合位点的移动，从而限制抗原识别。（c）单链双价特异抗体在链间加一个连接肽可以将双价特异抗体转换成单链双价特异抗体。（d）串联双价特异抗体两对VL结构域和VH结构域通过一个多肽链连接形成四价TandAb。（e）双亲合重靶向抗体（DARTs）DARTs的结构为VLA-VHB+VLB-VLA：VH结构域的第一个可变区与第二条链的VL连接，VH结构域的第二个可变区与第一条链的VL连接。链间的二硫键可以使DARTs稳定。DARTs结构小，半衰期短，可以增加Fc延长半衰期。2. 纳米抗体纳米抗体是天然纯在的最小抗体，仅含有重链的可变区(15kDa)（图11）。在缺少轻链的情况下，纳米抗体能够与相应的抗原结合。来源于骆驼的不同结合特异性的纳米抗体通过短连接肽连接形成BsAb。 图11 纳米抗体的示意图3. Dock-and-lock（DNL）抗体通过DNL方法，抗体片段形成类似PKA和AKAP结合的异源二聚体(图12)。图12 通过DNL方法形成双特异性抗体的示意图4. 其他双特异性/多特异性分子ScFvs也能与其他分子如TNF-α(以三聚体形式存在)、胶原蛋白XV或者XVII的三聚结构域、Fos或Jun的拉链型二聚结构域连接形成多价分子。延长半衰期的策略以ScFv为基础的BsAbs具有很多优势如易生产和具有较高的组织渗透性。它能够结合到抗原表位，但是空间效应上很难与完整抗体比较。同时由于缺少Fc结构域，免疫源性较低，可以避免与FcR结合。但是半衰期短，需要增加注射次数和剂量。延长半衰期从经济和治疗方面都有很大的意义。1. PEG化连接高灵活性和亲水性分子如PEG会增加动态水体积，提高半衰期。连接PEG的数量和大小会导致部分活力降低和降低抗体的亲和力（图13）。图13 PEG化避免BsAbs被降解和导致亲和力部分降低的示意图2. 与HSA融合ScFv-HSA能够延长半衰期，HSA能够与FcRn结合而不改变抗原结合力。ScFv-HSA不仅增加分子的大小，促进BsAbs的再循环，延长半衰期。被细胞吸收的HSA首先结合早期溶酶体的FcRn，避免降解，然后HSA重新定位在质膜上，重新释放到血清中。理论上，分子越小，越容易被肾消化。如ATN-103通过连接HSA增加分子的大小，而且也保留与TNF-α结合的特异性。3. 与Fc片段融合将ScFv-BsAbs与Fc融合，不仅增加分子大小，促进FcRn引起的再循环。通过这个方法设计的抗体DART MGD007用于治疗直肠癌。4. 多聚化多聚化通过调节大小和结合力来延长半衰期。BsAbs的临床应用BsAbs重定向免疫细胞靠近肿瘤细胞细胞毒性T淋巴细胞在癌症治疗的免疫应答过程中起着关键的作用。由于肿瘤细胞在免疫编辑过程中利用免疫逃逸机制使肿瘤特异T细胞应答受限。控制免疫细胞的一个策略就是利用BsAbs使T重定向接近肿瘤细胞，这个过程伴随着T细胞和靶肿瘤细胞之间形成瞬时的溶细胞突触，随后T细胞的增殖和激活导致肿瘤细胞裂解。除了T细胞，其他免疫细胞如巨噬细胞、单核细胞、粒细胞和自然杀伤细胞（NK）也会发挥杀死肿瘤细胞的效应。1. Triomab抗体使T细胞重定向到肿瘤细胞通过鼠-大鼠杂交瘤细胞高表达Triomab，BsAbs与单特异性抗体、轻链错配等副产物混合在一起，增加纯化难度；分别来自老鼠和小鼠的轻重链优先配对，使轻重链错配比例降至4%-10%，便于ProteinA纯化（图14）。图14 杂交瘤细胞表达的Triomab的ProteinA的纯化流程Trimab有三个功能，一个臂结合肿瘤相关抗原，第二臂结合T细胞的CD3，Fc结构域优先识别辅助细胞如巨噬细胞、树突细胞和NK细胞的受体Ⅰ(CD64)，Ⅱα（CD32α），ⅢFcγ（CD16）。T细胞激活，伴随着释放T细胞因子如TNF-α和IFNγ，接着辅助细胞重新定位到肿瘤细胞，并释放高水平的前炎症因子如IL-6，IL-2，GM-CSF和DC-CK1。肿瘤细胞被T细胞介导的裂解、激活的辅助细胞如巨噬细胞的ADCC作用所杀死（图15）。图15 Triomab®抗体将T细胞和其他辅助细胞重定向至肿瘤细胞卡妥索单抗属于Trimab，是第一个被用于癌症治疗的BsAbs。用同一种宿主细胞表达大鼠IgG2b和鼠IgG2a。相比于BiTE，IgG样BsAb具有较长的半衰期。在9到13天期间内，病人需要接受向腹膜内注射四到五次10-150ug。潜在的副反应是短暂的发烧、恶心、呕吐。卡妥索单抗被欧盟批准用于治疗EpCAM阳性的恶性上皮瘤。卡妥索单抗目前在进行治疗卵巢癌、胃肠癌、非小细胞肺癌、乳腺癌、腹膜转移癌的临床试验。2. BiTEs重定向T细胞到肿瘤细胞BiTEs平台运用的是串联ScFv BsAbs。博纳吐（Blinatumomab，Blincyto）结合T细胞的CD3和表达CD19的恶性肿瘤B细胞。是第一被US FDA批准的BsAbs用于治疗急性B细胞淋巴性白血病，大小为55kDa。另外，用于治疗临床2期和3期的ALL(急性淋巴性白血病)、临床3期的 DLBCL（弥漫性大B细胞淋巴瘤）、临床1期的NHL(非霍奇金淋巴瘤)。博纳吐通过重定向T细胞到肿瘤细胞，并且具有杀死肿瘤细胞的强大能力（图16）。不同的颗粒蛋白酶是形成T细胞和靶细胞之间溶细胞突触的必须组成。以此同时，T细胞开始增殖，并释放蛋白因子如TNF-a，IFN-r，IL-6，IL-2，IL-4和IL-10。BiTE分子非常有效，在非常低的浓度范围（10~100pg/mL）能够使T细胞重新定靶到CD19阳性淋巴瘤细胞上。剂量大于15ug/m2/day会导致体内肿瘤细胞消除。博纳吐在血清的半衰期低于2h，病人通过一个注射输入系统注入BiTE，并观察3-7天。博纳吐有一些缺陷，一些患者会忍受神经毒性和显示细胞激素释放症候（CRS）的症状。因为体积小，很容易被肾消除，病人每48小时需要更换注射包。有些患者会形成药物抗性，原因可能是CD19缺失、髓外复发和肿瘤细胞的PDL1上调。图16 BiTE®抗体重定向T细胞至肿瘤细胞3. DARTs重定靶T细胞到肿瘤细胞DARTs技术通过减小连接肽使BsAbs的稳定性提高、免疫源性降低。不像BiTEs，DARTs两个链的连接使抗原结合位点移动受限。因为DARTs结构的影响，在靶细胞和效应细胞之间形成稳定的接触。Moore et al.提到在使杀伤细胞重定向到B细胞淋巴瘤过程中CD19XCD3 DART比BiTEs分子更有效，可能因为DART与CD3的亲和力较高，与CD19的解离常数低。哺乳和真核表达系统可以用于抗体的表达，迄今为止，已经生成70多种DART。DART的功能主要有：激活杀伤细胞、定靶到受体上、结合到病原表位。目前有两个产品在临床试验中。MGD006通过重定向T细胞到白血病细胞治疗急性髓细胞样白血病（AML），具有两个特异的功能臂：一个靶作用白血病干细胞的CD123，另一个靶作用T细胞的CD3。目前MGD006应用于临床1期患有AML的病人。MGD007属于Fc-DARTs，具有较长的半衰期，通过重定向T细胞到gpA33阳性的结肠癌细胞从而裂解gaA33阳性细胞。目前应用于临床1期患有直肠结肠癌的病人。4. TandAbs重定向免疫细胞杀死肿瘤细胞TandAbs含有四个亲和位点，比BiTEs大，约为114kDa。半衰期比BiTE和双价特异性抗体长。TandAbs可以在细菌和哺乳细胞中表达。与BiTEs不同，TandAbs具有二价结合活力，提高了与靶细胞的结合能力。AFM13是鼠源的抗CD30结构域的四价BsAbs，它特异靶作用NK细胞和巨噬细胞的CD16A（图17），霍奇金和里德-斯泰伯格氏细胞高表达CD30。AFM13募集和激活NK细胞诱导CD3阳性的肿瘤细胞裂解。某些注射AFM13的病人可能出现剂量限制毒性症状如溶血性贫血。AFM13目前应用于临床2期患有霍奇金的病人。图17 AFM13重定向NK细胞杀死肿瘤细胞示意图BsAbs阻断信号通路细胞表面生长因子受体、酪氨酸激酶受体(RTK)主要参与癌症的形成。几种特异靶作用RTK的抗体如赫赛汀（转移性乳腺癌）、伊马替尼（CML和GIST）、吉非替尼（NSCLC）、西妥昔单抗（结肠直肠癌）用于癌症治疗。然而疾病的发生是由多个信号通路引起的，BsAbs可以同时靶作用两种细胞，比mAbs更有效。1. HSA-BsAbsMM-111是一种将两个scFvs与修饰HSA融合的bsAb。它可以同时靶作用HER2/HER3信号通路。对很多种癌症，HER2是一个有效的靶位点。HER3信号通路对于HER2抑制剂的抗药性有很重要的作用。双靶向HER2/HER3更有效。单独使用MM-111或与西妥昔单抗一起治疗患有HER2阳性的实体瘤的患者处于临床试验中。2. ScFv-IgGsMM-141是同时靶作用胰岛素样生长因子I受体（IGF-IR）和HER3（图18）。与MM-111不同，MM-141是一个IgG恒定区与两个ScFvs融合的IgG样BsAbs。IGF-IR和HER3可以激活PI3K/AKT/mTOR通路，MM-141结合IGF-IR和HER3阻断下游通路。MM-141目前应用于临床1期的肝细胞癌患者。图18 MM-141同时靶作用IGF-IR和HER3示意图3. 二合一抗体Duligotuzumab是一个噬菌体来源的DAF人源化抗体。它同时结合EGFR和HER3，导致HER家族下游信号通路受到抑制，下调引起癌症（如头颈癌和结肠直肠癌）病原发生的依赖于EGFR和HER3信号通路。患者接受EGFR抑制剂西妥昔单抗治疗经常会产生抗EGFR抗性。当结合放疗后，Duligotuzumab能够克服药抗，增强放疗的效果。Duligotuzumab目前应用于临床期患有上皮肿瘤和颈部鳞状细胞癌的患者。接受Duligotuzumab治疗患者极易产生副作用如粒细胞减少性发热、血钾过少、恶心和脱水。靶作用肿瘤血管生成的BsAbs肿瘤血管生成是肿瘤生长和转移的关键过程。很多肿瘤血管生成因子包括内皮生长因子受体2（VEGFR2）、VEGFR3、VEGFA、血管生成素、血小板源生长因子（PDGFs）参与了肿瘤血管的生成。很多癌症治疗通过消耗这些蛋白来破坏肿瘤血管生成。双重靶向这些肿瘤血管生成因子会获得更好的效果。RG7221是靶作用肿瘤血管生成因子（VEGFA）和血管生成素（Ang-2）的人IgG样CrossMab。。在临床前模型中，与单信号通路抑制剂相比，RG7221对肿瘤血管生成和肿瘤的生长有明显的抑制。RG7221目前应用于患有结肠直肠癌的患者的临床II研究。根据临床I的研究数据，接受RG7221治疗的病人可能容易产生高血压、无力、头疼和疲劳等反应。RG7716是一个与RG7221相似的CrossMab，也能够同时阻断VEGFA和Ang2，目前应用于患有湿型年龄相关性黄斑变性（wet AMD）的研究。阻断细胞因子的BsAbs一些细胞因子被认为是引起炎症发生和自体免疫疾病的关键因子。因此阻断这些因子是有治疗潜力的。例如，抑制TNF-a对于牛皮癣、银屑病关节炎、克罗恩病、溃疡性结肠炎、少年关节炎和许多其他疾病有很好的治疗效果。其他有效的因子包括IL-6，IL-7，IL-1，IL-12，TGF-β，IL-4和IL-13。纳米抗体Ozoralizumab（ATN-103）是由Ablynx研发的小的三价双特异性纳米抗体，与TNF-a和HSA具有较高的亲和力。与白蛋白结合可以提高血清中的亲和力。Ozoralizumab完成了治疗患有RA的患者临床II试验，对RA有明显的改进。Ozoralizumab展示了特异的分子特性如体积小、低免疫源性、长半衰期，让人们更加期待它在临床的应用。Ablynx也研发了其他类似的纳米抗体包括治疗RA抗IL-6R/HSA的ALX-0061和治疗炎症疾病抗IL-17A/F的ALX-0761。SAR156S97SAR156597是一个四价双特异串联IgG，可以同时结合IL-13和IL-4。从结构上看，是一个N端与抗IL13的抗体可变区融合的IgG分子（抗IL4抗体）。它已经完成特发性肺纤维变性疾病的临床I/II研究。作为运载工具的BsAbsBsAbs的一个有趣的应用就是运输如药物、放射性同位素标记和纳米颗粒。这些运输物一旦释放出来，空载的BsAbs分子在血清中被清除。BsAbs也被用于在肿瘤位点富集运输物，这种策略明显的延长血清中的半衰期。DNL利用DNL方法生产双特异性TF2，用于肿瘤显影和放射免疫疗法，能够与CEA和99mT标记的组胺-琥珀酰-甘氨酰(HSG)半抗原特异结合。在临床试验中，先注射TF2，然后99mT标记的HSG被释放，最后血清中BsAbs被清除。肿瘤对99mT吸收提高，伴随着肿瘤/血液比例的提高。TF2目前应用于患有结肠直肠癌的患者临床I期的研究。BsAbs临床前研发1. 应用于穿越血脑屏障（BBB）的BsAbsBsAbs一个最有前途的应用就是穿越BBB从而靶作用神经性疾病的病原发生中介。BBB形成单特异性抗体治疗的禁区。Couch et al.设计了一个能够结合转铁蛋白受体 (TfR)和β位淀粉样前体蛋白裂解酶1 (BACE1)的BsAbs去克服这个障碍。大脑内皮细胞表面高表达TfR。BACE1是导致阿尔茨海默病发生的天门冬氨酰蛋白酶，靶作用BACE1是长期寻找治疗阿尔茨海默病的策略。与TfR结合后，经受体介导的胞吞作用运输到大脑。BsAb与TfR的亲和力低，bsAb可以从内皮释放进入大脑靶作用BACE1。一个临床前研究显示这种BsAb能够减轻疾病的症状。2. 用于诊断试验的BsAbsBsAb可被用于诊断试验。一个bsAb被设计成结合特异抗原和检测结构域如辣根过氧化物酶。BsAbs可以作为交联剂，同时结合抗原和报告分子。在免疫试验中，单特异性捕获抗体被固定在固体表面，结合血清中相应的抗原。加入BsAbs，结合抗原和报告分子。基于BsAb的免疫试验应用于感染了肺结核、乙型肝炎、大肠杆菌、百日咳博德特氏菌、非典型肺炎和其他传染性疾病的检测分析。另外，BsAbs也被用于其它诊断应用如免疫组织化学和放射免疫诊断。与单特异性抗体相比，BsAbs可以简化诊断试验，减少假阳性反应。基于BsAb的诊断可以特异检测细菌或病毒抗原，便于早期检测。3. 应用于病原体治疗的BsAbs由于过度使用广谱抗生素，许多致病菌产生了抗生素耐药性，有些甚至能够抵抗多种抗生素和化学剂。多重抗药物性的产生为研发新的抗生素构成巨大的威胁。一个新的有效的BsAbs（BiS4αPa）用于治疗铜绿假单胞菌感染。铜绿假单胞菌是医院内肺炎和囊性纤维化患者死亡的重要因素。由于抗药性，抗铜绿假单胞菌的单一表位的抗生素是无效的。双特异性BiS4αPa能与对免疫逃逸和生物膜形成具有重要作用的细胞外多糖Psl结合，同时能与参与毒性因子分泌的PcrV结合。在动物实验研究中证明BiS4αPa具有优越的保护活性。BiS4αPa目前应用于治疗铜绿假单胞菌患者的临床研究。除了BiS4αPa之外，开发了很多BsAbs用于重定向细胞毒性T淋巴细胞杀死HIV、防止HBV感染或促进噬菌体清除。讨论BsAbs不仅将治疗（如T细胞、药物）和靶细胞（如肿瘤）联系起来，而且同时阻断两个不同的病原发生中介。在不久的将来，BsAbs可能会改进治疗癌症、自体免疫疾病、炎症疾病的方向。两个被批准的BsAbs具有令人印象深刻的治疗效果。BsAbs的成功引起制药公司的关注，同时不同的公司将设计新的形式。除了成功，一些关键的障碍依然存在，仅有少数的形式进入临床试验。大规模的生产和纯化是一个长期的所要追逐的目标。理想的平台应该围绕整个开发过程，从研发和临床前研究到临床材料生产，到快速研发有潜力的BsAbs和在短时间内纯化得到临床级别的BsAbs。当设计BsAbs形式时，简化结构和生长过程、运用有效的生产平台是关键。配套靶位点的确定和靶位点之间潜在的协同效应也给BsAb带来了极大的挑战，必须具备高通量筛选的平台。免疫源性对药物设计和开发也是一个复杂的难题，很多临床副作用阻碍了BsAbs的成功。随着科技的发现，希望可以开发出更多被批准上市的BsAbs。参考文献1. Gaowei Fan, et al. Journal of Hematology & Oncology (2015) 8:1302. Tarcsa E, et al. Bispecific Antibodies. Berlin, Heidelberg: Springer Berlin Heidelberg; 2011. p. 171–85.3. Eigenbrot C, et al. Curr Opin Chem Biol. 2013;17(3):400–5.4. Labrijn AF, et al. Nat Protoc. 2014;9(10):2450–63.5. Fischer N, et al. Nat Commun. 2015;6:6113.6. Goldenberg DM, et al. J Nucl Med. 2008;49(1):158–63.7. Fishburn CS. J Pharm Sci. 2008;97(10):4167–83.8. Lindhofer H, et al. J Immunol. 1995;155(1):219–25.9. Ecker DM, et al. The therapeutic monoclonal antibody market. mAbs. 2015;7(1):9–14.近期直播推荐识别微信二维码，添加生物制品圈小编，符合条件者即可加入生物制品微信群！请注明：姓名+研究方向！版权声明本公众号所有转载文章系出于传递更多信息之目的，且明确注明来源和作者，不希望被转载的媒体或个人可与我们联系(cbplib@163.com)，我们将立即进行删除处理。所有文章仅代表作者观点，不代表本站立场。