IGF-2

Potential to more than double the addressable patient population living with hypoglycemia resulting from insulin receptor over-activation (tumor hyperinsulinism)REDWOOD CITY, Calif., March 06, 2024 (GLOBE NEWSWIRE) -- Rezolute, Inc. (Nasdaq: RZLT) (“Rezolute” or the “Company”), a clinical-stage biopharmaceutical company committed to developing novel, transformative therapies for serious metabolic and rare diseases, today announced results from a preclinical pharmacology study that validate the potential for its lead clinical compound, RZ358, to treat individuals with non-islet cell tumors (NICTs) that have uncontrolled hypoglycemia. Tumor hyperinsulinism (HI) may be caused by a variety of different tumor types, resulting in islet cell tumor hypoglycemia (ICTH) and NICTH. The Company previously reported on the successful use of RZ358 under its Expanded Access Program (EAP) to treat patients with insulin-producing pancreatic islet cell tumors (ICTs), or insulinomas, causing severe and uncontrolled hypoglycemia. The therapeutic potential of RZ358 in this setting was anticipated given that ICTH is mediated by insulin and that RZ358 is known to work at the insulin receptor to decrease excess insulin binding and activity. However, it was unknown if RZ358 would have utility in NICTH where hyperinsulinism is mediated by hormones such as insulin-like growth factor-2 (IGF-2) or its variants, which likewise cause hypoglycemia by binding to and activating the insulin receptor. To test this, the Company recently completed in vitro pharmacology studies to evaluate the impact of clinically relevant concentrations of RZ358 on insulin receptor activation by IGF-2, compared to insulin. This was tested at the relative concentrations of each ligand that activate the insulin receptor and are physiologically relevant in tumor HI caused by ICTH and NICTH, respectively. These experiments successfully demonstrated the ability of RZ358 to similarly blunt both IGF-2 and insulin-mediated insulin-receptor signaling, at levels of these ligands that are disease-relevant in humans. “These data demonstrate proof of the ligand-agnostic mechanism of action of RZ358 and therefore validate its broad utility in treating hypoglycemia resulting from any form of hyperinsulinism, including expanded tumor indications,” said Dr. Brian Roberts, Chief Medical Officer of Rezolute. “Coupled with known outcomes from our clinical trials in congenital HI and the positive outcomes seen with ICTH in our expanded access program, we are excited by the potential for RZ358 to provide dramatic therapeutic benefit to cancer patients who often have limited treatment options for managing serious and uncontrolled hypoglycemia, which can accompany their cancer and disrupt treatment plans.” The Company recently reported on its successful interaction with the U.S. Food and Drug Administration (FDA) in January 2024 regarding the potential to initiate a single registrational study in patients with hypoglycemia due to tumor HI. The Company will continue to evaluate the feasibility of a development program in this indication, with the possibility of including both ICTH and NICTH patients. The inclusion of NICTH patients in a potential addressable market for RZ358 in tumor HI would more than double the population. The Company is also currently evaluating RZ358 in a Phase 3 clinical trial in congenital HI, which is a rare pediatric condition where, similar to ICTH, children overproduce insulin creating a dangerous hypoglycemic state. About Tumor Hyperinsulinism (HI)Tumor HI may be the result of two distinct types of tumors: islet cell tumors (ICTs) and non-islet cell tumors (NICTs), both of which lead to hypoglycemia due to excessive activation of the insulin receptor. Insulinomas are the most common type of functional ICT and cause hypoglycemia because of over production of insulin. NICTs can cause hypoglycemia by producing and secreting insulin-like paraneoplastic substances such as IGF-2 or related variants that bind to and activate the insulin receptor. This form of hypoglycemia can occur in more than 15 different tumor types, 60 percent of which are malignant, including hepatocellular carcinoma. The total addressable market for the combined indications causing tumor HI is estimated to be approximately 4,500 patients in the U.S. alone, including approximately 1,500 with ICTH and 3,000 with NICTH. The unique mechanism of action of RZ358 to attenuate excess insulin receptor activation mediated by insulin and related substances makes the therapy a potential universal treatment for hypoglycemia resulting from any form of hyperinsulinism. About RZ358RZ358 is a fully human monoclonal antibody that works downstream from the pancreas and other sources of insulin or related paraneoplastic substances, and instead binds to a unique allosteric site on insulin receptors in the liver, fat, and muscle. The antibody counteracts excess insulin receptor activation by insulin and other effector substances (such as IGF-2), thereby improving hypoglycemia. Because RZ358 acts downstream from the pancreas at the insulin receptor, it has the potential to be universally effective at treating hypoglycemia due to congenital HI, regardless of the causative genetic defect, as well as acquired forms of HI such as those mediated by insulinomas (ICTs) and other tumor types (NICTs). RZ358 received Orphan Drug Designation in the United States and European Union for the treatment of congenital HI, as well as Orphan Drug Designation and Pediatric Rare Disease Designation in the U.S. In the Phase 2 RIZE study, participants with congenital HI ages two and older nearly universally achieved significant improvements in hypoglycemia across multiple endpoints, including the primary and key secondary endpoints planned for the sunRIZE study. At doses and exposures that are planned for the Phase 3 study, RZ358 was generally safe and well-tolerated, and resulted in median improvements in hypoglycemia exceeding 80%. Based on the RIZE clinical trial outcomes and the evidence of benefit in this serious condition with substantial unmet medical need, RZ358 was subsequently granted a priority medicines (PRIME) designation by the European Medicines Agency (EMA) and an Innovation Passport designation by the U.K. Innovative Licensing and Access Pathway (ILAP) Steering Group for the treatment of congenital HI. RZ358 also received Orphan Drug Designation status in the European Union for the treatment of Insulinoma, the primary cause of ICTH. About Rezolute, Inc. Rezolute strives to disrupt current treatment paradigms by developing transformative therapies for devastating rare and chronic metabolic diseases. Its novel therapies hold the potential to both significantly improve outcomes and reduce the treatment burden for patients, treating physicians, and the healthcare system. Rezolute is steadfast in its mission to create profound, positive, and lasting impacts on patients’ lives. Patient, clinician, and advocate voices are integrated in the Company’s drug development process. Rezolute places an emphasis on understanding the patient’s lived experiences, enabling the Company to boldly address a range of severe conditions. For more information, visit www.rezolutebio.com. Forward-Looking Statements This release, like many written and oral communications presented by Rezolute and our authorized officers, may contain certain forward-looking statements regarding our prospective performance and strategies within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 and are including this statement for purposes of said safe harbor provisions. Forward-looking statements, which are based on certain assumptions and describe future plans, strategies, and expectations of Rezolute, are generally identified by use of words such as "anticipate," "believe," "estimate," "expect," "intend," "plan," "project," "seek," "strive," "try," or future or conditional verbs such as "could," "may," "should," "will," "would," or similar expressions. These forward-looking statements include, but are not limited to statements regarding the Innovation Passport designation, the RZ358 Expanded Access Program, the ability of RZ358 to become an effective treatment for congenital hyperinsulinism, the effectiveness or future effectiveness of RZ358 for the treatment of congenital hyperinsulinism, and statements regarding clinical trial timelines for RZ358. Our ability to predict results or the actual effects of our plans or strategies is inherently uncertain. Accordingly, actual results may differ materially from anticipated results. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release. Except as required by applicable law or regulation, Rezolute undertakes no obligation to update these forward-looking statements to reflect events or circumstances that occur after the date on which such statements were made. Important factors that may cause such a difference include any other factors discussed in our filings with the SEC, including the Risk Factors contained in the Rezolute’s Annual Report on Form 10-K and Quarterly Reports on Form 10-Q, which are available at the SEC’s website at www.sec.gov. You are urged to consider these factors carefully in evaluating the forward-looking statements in this release and are cautioned not to place undue reliance on such forward-looking statements, which are qualified in their entirety by this cautionary statement. Investors & Media:Christen BaglaneasRezolute, Inc.cbaglaneas@rezolutebio.com (508)272-6717 A photo accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/165f8dbc-1fce-47b8-ac3f-0cf6fb4170cb

中文摘要人类表皮生长因子受体3（human epidermal growth factor receptor 3，HER3）作为表皮生长因子受体家族中的一员，通过与其他受体形成异源二聚体发挥信号转导的功能。头颈部鳞状细胞癌（head and neck squamous cell carcinoma，HNSCC）是全球第6大常见癌症，起病隐匿且总体生存率低。HER3在HNSCC中高表达。HER3的表达和激活与HNSCC治疗中靶向其他受体的药物〔例如靶向表皮生长因子受体的单克隆抗体（单抗）西妥昔单抗或程序性死亡受体1阻断剂〕以及某些化学治疗药物的治疗获得性耐药有关。目前，HER3已经成为HNSCC治疗非常有前景的候选靶点。此文综合近年来国内外对靶向HER3治疗在HNSCC中的研究，对HER3参与HNSCC肿瘤进程的机制、HER3与HNSCC当下临床治疗策略的关联，以及包括处于临床试验的11种单抗药物、5种双特异性抗体药物及其他多种类型的靶向HER3的药物在HNSCC治疗中的开发进展进行综述。正文人类表皮生长因子受体3（human epidermal growth factor receptor 3，HER3）又称幼红细胞白血病病毒癌基因同源物3（erythroblastic leukemia viral oncogene homolog 3，ErbB3），是人体中经典的受体酪氨酸激酶（receptor tyrosine kinase，RTK），属于表皮生长因子受体（epidermal growth factor receptor，EGFR）家族。HER3 具有与家族其他成员不同的独特构型，胞内酪氨酸激酶活性较低，无法直接与三磷酸腺苷相结合，需与其他有酪氨酸激酶活性的EGFR家族成员形成异源二聚体复合物来发挥作用。而由于HER3胞内结构域11个酪氨酸磷酸化位点中有6个磷脂酰肌醇3激酶（phosphatidylinositol 3-kinase，PI3k）p85 亚基结合位点，使得HER3胞内区酪氨酸激酶羧基末端活化后与PI3K的p85亚基结合，可以强烈激活PI3K/Akt通路。PI3K/Akt通路作为促进肿瘤细胞增殖的主要信号通路，涉及调控基因表达、细胞代谢和细胞骨架重排。研究显示，对PI3K/Akt途径有直接和间接抑制作用的药物会引起叉头转录因子盒O依赖性HER3转录升高，并通过PI3K-Akt负反馈调节上调和激活HER3的表达，再次激活下游途径，从而出现耐药。另有研究表明，HER3主要配体神经调节蛋白1（neuregulin-1，NRG1）可以通过旁分泌与自分泌途径共同参与HER3信号转导等过程。HER3的主要相关蛋白、信号通路和功能见图1。1项对超过750个不同来源的肿瘤进行的定量逆转录PCR表达谱分析显示，头颈部鳞状细胞癌（head and neck squamous cell carcinoma，HNSCC）表达的NRG1水平最高。头颈部肿瘤是全球最常见的恶性肿瘤之一，超过95%的病理类型是鳞状细胞癌。HNSCC是指位于鼻旁窦、鼻腔、口腔、咽部和喉部由鳞状细胞引起的组织学癌症，是全球第6大癌症，起病隐匿，且总体生存率不高，中位生存期低于1年。在免疫检查点阻断（immunecheckpoint blockade，ICB）治疗出现之前，全身化学治疗（化疗）被用作标准的一线方案，即将顺铂或卡铂和5-氟尿嘧啶、人鼠嵌合抗EGFR单克隆抗体（单抗）西妥昔单抗联用。ICB疗法的发展为抗癌治疗提供了强有力的支撑，其中程序性死亡受体1（programmed death-1，PD-1）/程序性死亡受体配体1抑制剂在多项单药或联合用药临床试验中被证实可以有效延长HNSCC患者的生存时间，且较传统治疗方案不良反应发生率更低。然而，治疗获得性耐药在HNSCC患者中很常见，西妥昔单抗和PD-1/程序性死亡受体配体1抑制剂在HNSCC中均疗效有限，仅有＜20%的患者获得了持久的受益。HER3的表达和激活与HNSCC治疗中其他靶向药物和某些化疗药物的治疗获得性耐药有关，同时HER3的促进细胞增殖作用提示靶向HER3治疗具有一定的临床潜力。本文对HER3靶点靶向治疗在HNSCC中的研究现状及相关进展进行综述，总结HER3靶点与HNSCC当下治疗策略的关系，以及几种靶向HER3或与HER3相关的HNSCC治疗策略。1HER3与HNSCC当下临床治疗策略HER3在多种人类癌细胞中表达，其过表达与癌症包括头颈部肿瘤患者的生存率较低有关。在HNSCC中，主要于膜上过表达HER3的肿瘤预后较差。HER3高表达的原发性肿瘤似乎更倾向于发生淋巴结转移，且超过30%的转移淋巴结中存在HER3过表达。此外，与正常组织相比，在异型增生和HNSCC中发现了HER2/HER3、HER3/HER4、EGFR/HER2/HER3以及EGFR/HER2/HER3/HER4共表达。HER3与家族其他成员的这些共表达与生存率低、疾病进展和/或转移显著相关。由于当某个ErbB被阻断时，其他RTK可以补偿被阻断的受体丢失的信号传导，因此HER3表达可作为多种靶向治疗的旁路机制，异常的HER3信号传导导致了患者对多种靶向治疗药物及化疗药物的治疗获得性耐药。由于HER3还可以与HER2、HER4、原癌基因蛋白质c-Met等形成异源二聚体，导致EGFR信号传导的平行信号通路异常激活，因此西妥昔单抗对HER3和HER3相关二聚体的上调是HNSCC中EGFR靶向疗法获得性耐药的一种机制。早期研究表明，HER2/HER3介导的信号传导与头颈癌中的EGFR酪氨酸激酶抑制剂（tyrosine kinase inhibitor，TKI）吉非替尼治疗获得性耐药相关，在对EGFR/HER2双重TKI拉帕替尼敏感的细胞系中，拉帕替尼的敏感性与强活化的HER3和HER3配体NRG1的升高密切相关。后来也有人提出，自分泌NRG1信号传导上调以及HER2/HER3二聚体的增加，是HNSCC中西妥昔单抗对EGFR抑制的耐药机制。在TKI包括厄洛替尼和吉非替尼治疗获得性耐药患者中，HER2、HER3上调也被认为是耐药机制的一部分。同时，无论是在体外还是体内试验中，靶向抑制HER3都可以使西妥昔单抗耐药的HNSCC细胞对西妥昔单抗重新敏感。在另1项研究中，原癌基因c-met通过增加HER3/P13K信号传导引起吉非替尼和西妥昔单抗耐药，然而由于HNSCC中原癌基因c-met的拷贝数增加很少见（1%~2%TCGA队列），因此该机制只能解释先天耐药病例的一小部分。由于HER3是PI3K/Akt/哺乳动物雷帕霉素靶蛋白（mammalian target of rapamycin，mTOR）存活信号传导的重要激活剂，因此它也导致了其他靶向治疗的耐药性。在HNSCC临床前模型中，HER3靶向可以增强PI3Kα选择性抑制剂BYL719的生长抑制作用。此外，另1项研究提出HPV＋HNSCC相较于HPV﹣HNSCC对PI3K抑制剂存在内在耐药性，这种药物敏感性的差异可能归因于PI3K抑制剂治疗HPV﹣HNSCC细胞系后HER3对Akt激酶的再激活。同时，共靶向HER3和PI3K可能是克服HPV﹣HNSCC肿瘤中PI3K抑制剂耐药性的有效治疗策略。在ICB治疗的临床前研究中，抗体介导的靶向HER3阻断通过抑制HER3-PI3K-Akt-mTOR致癌信号传导，可以逆转免疫抑制肿瘤微环境，从而发挥有效的抗肿瘤作用。对HER3抗体偶联药物（antibody-drug conjugate，ADC）U3-1402的1项研究显示，U3-1402靶向HER3发挥其抗肿瘤作用的同时，可以通过免疫激活与PD-1阻断存在潜在的协同作用，使表达HER3的肿瘤对PD-1阻断重新敏感。此外，在1项针对HER3疫苗的研究中，使用编码全长人HER3的重组腺病毒载体Ad-HER3-FL进行免疫，可诱导HER3靶向疫苗激活HER3特异性T细胞并诱导抗HER3特异性抗体，改变肿瘤中的T细胞浸润，并影响对ICB的应答。因此，对于抗PD-1单抗的治疗受益有限群体而言，靶向HER3抑制的治疗策略与PD-1阻断联用，或许可以为HNSCC提供多模式精准免疫治疗方法。2靶向HER3的抗体药物在HNSCC治疗中的开发进展目前，已有11种靶向HER3的单抗产品正在针对HNSCC进行临床前或临床试验。这些靶向HER3的单抗抑制肿瘤的作用机制主要包括：阻断受体与配体的结合、使受体锁定为非活性构象、促进受体的内化与降解以及诱导抗体依赖细胞介导的细胞毒作用（antibody-dependent cell-mediated cytotoxicity，ADCC）和补体依赖的细胞毒作用（complement dependent cytotoxicity，CDC）直接杀死肿瘤细胞。这些靶向HER3的单抗均为IgG抗体，其中IgG1抗体8种，重组IgG1/IgG3抗体（GSK2849330）和IgG2抗体（MM-121）各1种。除单抗外，将适应证瞄准HNSCC的5种双特异性抗体（双抗）和2种ADC也在开发中。此外，正在研发的还有泛抗HER家族单抗混合物、HER3疫苗、嵌合抗原受体（chimeric antigen receptor，CAR）T 细胞疗法、抗金属蛋白酶抑制剂等。2.1单抗临床开发中与HNSCC相关且靶向HER3的单抗汇总如下。Barecetamab（ISU104）是由韩国ISU ABXIS公司开发的全人源IgG1单抗，与HER3胞外结构域Ⅲ结合，处于早期临床开发阶段。该抗体阻断HER3的激活及与其他HER伴侣的二聚化，并使HER3的下游信号失活。在体内，除HNSCC之外，ISU104同时也在非小细胞肺癌、结肠癌、胰腺癌、乳腺癌的皮下异种移植肿瘤模型中显示出超过70%的肿瘤生长抑制。ISU104在获得性西妥昔单抗耐药异种移植肿瘤模型中也显示出抗肿瘤作用。最近，Hong等报道了ISU104在NRG1表达高或具有NRG1融合或致癌ErbB3突变等遗传改变的模型中的抗肿瘤功效。CDX-3379（KTN3379）是由美国 Celldex 公司开发的人源IgG1λ单抗，与HER3结构域Ⅱ和Ⅲ之间边界的独特表位具有非常高的亲和力，该表位将HER3锁定在其非活性构象中，并抑制配体依赖性和配体非依赖性信号传导。因此，该抗体抑制配体依赖性和配体非依赖性HER3活化。临床前阶段，CDX-3379联合西妥昔单抗或BYL719可增强HNSCC异种移植模型的生长抑制。在近期1项临床前研究中，CDX-3379介导的HER3阻断通过抑制HER3-PI3K-Akt-mTOR致癌信号传导并伴随逆转免疫抑制肿瘤微环境，可以发挥有效的抗肿瘤作用，因此靶向HER3和PD1联合用药可能为PIK3CA野生型HNSCC提供多模式精准免疫治疗方法。在临床试验中，单独使用CDX-3379或与西妥昔单抗联合使用耐受性良好，并可使HNSCC肿瘤消退。Seribantumab（SAR256212，MM-121）是由美国Merrimack公司开发的靶向HER3的全人源IgG2单抗，与NRG1竞争结合HER3，阻止二聚化并诱导HER3内化和降解。该抗体由噬菌体展示的抗原结合片段（Fab）文库产生，被转化为全长人IgG2形式，目的是最大限度地减少免疫原性和免疫效应介导的脱靶不良反应。在HNSCC的临床前模型中，MM-121降低了HER3的磷酸化。此外，在HNSCC的细胞系和动物模型中，MM-121与西妥昔单抗联合用药通过抑制HER3、EGFR、PI3K/Akt和胞外信号调节激酶的活化显示出更有效的细胞和肿瘤生长抑制。同时发现，西妥昔单抗耐药的HNSCC模型中HER3上调，并且在HNSCC中，EGFR和HER3的双重靶向优于单独EGFR靶向。然而在进入临床后，MM-121虽可与几种药物安全联合使用且耐受性良好，但未产生明显的临床获益。Elgemtumab（LJM716）是从Morphosys HuCal Fab噬菌体展示文库中分离的全人源IgG1单抗，由瑞士诺华公司和法国赛诺菲安万特公司开发。LJM716可与位于HER3胞外结构域Ⅱ和Ⅳ之间的界面构象表位结合，将HER3捕获在无活性构象中并抑制配体依赖性和独立的HER3信号传导激活。LJM716在体内异种移植研究中显示出有效的抗肿瘤作用，并且在相关肿瘤模型中证明了与曲妥珠单抗或西妥昔单抗联合使用的肿瘤生长抑制效果。在日本1项对HNSCC、胃癌、HER2过表达乳腺癌患者的临床研究（NCT01911936）中，LJM716表现出良好的耐受性，并且队列中观察到一定程度的肿瘤缩小。该研究推荐扩增剂量为每周1次40 mg/kg QW（NCT01598077）。REGN1400是全人源IgG单抗，由美国再生元公司开发，可抑制HNSCC和乳腺癌细胞系及异种移植物的NRG结合、HER3和Akt的磷酸化以及这些肿瘤细胞系和异种移植物的体外生长。REGN1400联合抗EGFR或抗HER2抗体可更有效地抑制肿瘤生长，同时还会增加HNSCC异种移植模型中抗EGFR治疗的敏感性。REGN1400在Ⅰ期临床试验（NCT01727869）中，作为单药治疗或与厄洛替尼或西妥昔单抗联合使用，表现出良好的安全性和耐受性，该研究还计划在HNSCC和结直肠癌扩大队列。Patritumab（AMG-888，U3-1287）是全人源IgG1单抗，可抑制配体与HER3的结合并诱导受体内化和降解，由日本第一三共公司开发，是目前在临床开发中进展最快的HER3靶向药物。此外，没有检测到针对Patritumab的人抗人抗体，初步结果表明高HER3表达或扩增与临床疗效之间存在相关性趋势。Patritumab在HNSCC细胞和异种移植物中也显示出其作为单药以及与帕尼单抗联合使用的潜力。在HNSCC和肺癌模型中，Patritumab增强了放射敏感性。在2项Ⅰ期临床试验（NCT00730470和JapicCTI-101，262）中，U3-1287治疗耐受性高达20 mg/kg，具有良好的耐受性和良好的药代动力学特征。在另1项已经完成的Ⅰ期临床试验（NCT02350712）中，U3-1287（18 mg/kg负荷剂量，9 mg/kg维持剂量）联合西妥昔单抗和铂类治疗在HNSCC中可耐受且有效。GSK2849330是由英国葛兰素史克公司开发的IgG1/IgG3嵌合、糖工程人源化的单抗，针对HER3胞外结构域Ⅲ，由于分别与人Fc-γ受体（FcyRⅢa）和人补体蛋白C1q具有高结合亲和力，因此可以增强ADCC和CDC，也可以阻断癌细胞中的HER3/NRG1的信号传导，在NRG1融合肿瘤中表现出较好的抗肿瘤活性。GSK2849330在Ⅰ期临床试验（NCT01966445）中表现出良好的耐受性和安全性，每周30 mg/kg未出现剂量限制性毒性，同时观察到的最大血浆浓度为778.47 μg/ml。AV-203（CAN017）是由美国AVEO公司和美国Biogen公司开发的人源化IgG1κ单抗，可以阻断NRG1与受体的结合并诱导HER3降解。AV-203对患者来源的肿瘤异种移植模型（包括HNSCC、非小细胞肺癌、乳腺癌、肾癌、胰腺癌等）显示出临床前活性。此外，NRG1表达水平可预测AV-203在临床前人类癌症模型中对HER3抑制的反应。Ⅰ期临床试验（NCT01603979）证实，AV-203在最大剂量（每2周20 mg/kg）以下是安全的且耐受性良好。Lumretuzumab（GE-huMab-HER3，RG7116，RO5479599）是由瑞士罗氏公司开发的糖工程人源化IgG1单抗。该抗体与HER3的结构域Ⅰ结合，通过阻断HER3胞外结构域和NRG结合来抑制HER3信号传导的激活。其Fc区被糖化工程化以增加对免疫效应细胞上FcyRⅢa的亲和力。与非糖工程抗体相比，这种单抗使得ADCC在体内和体外都能得到更有效的激活。由于Lumretuzumab已被证明在体外存在和不存在HRG的情况下都能阻断HER3活化，因此Lumretuzumab不仅在治疗上靶向依赖于活性HER3信号传导的细胞，而且还靶向那些在细胞表面表达非活化HER3的细胞。在与HNSCC相关的临床试验NCT01482377中，RG7116加西妥昔单抗/厄洛替尼的Ⅰb期研究发现NRG是实体瘤患者的潜在生物标志物；此外，队列中有2例高HRG mRNA表达水平的患者获得了出乎意料的受益，其中1例HNSCC患者达到延长的完全缓解，1例卵巢癌患者达到延长的部分缓解。SIBP-A03是由上海生物制品研究所有限责任公司自主研发的IgG1单抗，为国内首家获得临床批件的抗HER3抗体药物。SIBP-A03与HER3的结构域Ⅲ结合，在黑色素瘤（A431细胞系）、胰腺癌（Bxpc3细胞系）的体外试验和小鼠肿瘤模型中，表现出明显的肿瘤生长抑制作用，并且与西妥昔单抗联合使用具有一定的协同作用。Ⅰa期临床试验（NCT05203601）正在进行中，患者队列主要为晚期HNSCC或乳腺癌患者。HMBD-001是由新加坡蜂鸟生物科技公司开发的IgG1抗体，已进入临床阶段。它直接结合并阻断HER3的异二聚化界面，并有可能抑制HER3的配体依赖性和独立激活以及致癌信号传导，通过靶向位于HER3与HER2或EGFR形成异二聚体的界面的关键表位，抑制所有HER3异二聚化的过程。在评估HMBD-001的临床前模型中，观察到HMBD-001与其他现有的抗HER3抗体相比，具有更好的亲和力和更强的肿瘤抑制作用。HMBD-001近期的开发计划或将侧重于4种适应证：NRG1融合驱动型癌症、转移性去势抵抗性前列腺癌、转移性结直肠癌和HNSCC。2.2双抗临床开发中与HNSCC相关且靶向HER3的双抗汇总如下。Duligotuzumab（MEHD7945A，RG7597）是由美国基因泰克公司开发的、靶向EGFR和HER3的全人源IgG1双抗，从噬菌体展示Fab文库中分离出来，包含2个相同的Fab。MEHD7945A在几种临床前模型中强烈抑制肿瘤包括人表皮样癌、胰腺癌、乳腺癌、结直肠癌、HNSCC和肺癌生长，特别是与化疗联合使用时。MEHD7945A单药治疗或与顺铂联合使用，在来自HNSCC和非小细胞肺癌的厄洛替尼和西妥昔单抗的耐药模型中证明了其疗效。值得关注的是，MEHD7945A还能诱导ADCC。然而2项临床试验（NCT01207323、NCT01577173）的结果显示，MEHD7945A的活性与西妥昔单抗相似，但并未展现出优于西妥昔单抗的效果。Zenocutuzumab（Zeno，MCLA-128）是荷兰Merus公司开发的靶向HER2（结构域Ⅰ）和HER3（结构域Ⅲ）的IgG1双抗，可以与HER2对接并阻断与HER3结合的配体，通过HER2-HER3异二聚体抑制致癌信号传导；同时由于IgG1的糖工程修饰还具有增强的ADCC活性。除了在对HER2靶向治疗（曲妥珠单抗和T-DM1）耐药的模型及乳腺癌、胃癌和胰腺癌模型中显示出疗效，该抗体在化疗耐药NRG1融合阳性转移性癌症患者中也显示出疗效，抑制NRG1融合阳性癌症模型的生长，在Ⅰ/Ⅱ期临床试验中也报告了良好的耐受性和抗肿瘤活性。SI-B001是四川百利天恒药业股份有限公司开发的靶向EGFR和HER3的IgG-单链Fv（ single-chain antibody fragment，scFv）2 四价双抗，由 1 个完整的IgG组成，具有2条重链和2条轻链，以及2个scFv段连接到重链或轻链的C端或N端。SI-B001在结肠癌、HNSCC或食道癌异种移植模型中证明了其疗效，在后两种模型中几乎完全抑制了肿瘤的生长，目前正在进行的国内外临床试验（NCT05022654、NCT05044897、NCT05054439、CTR20211979、CTR20212937）的患者队列选择也多为HNSCC及食管癌。MM-111是由美国Merrimack公司开发的靶向HER2和HER3的双抗，由2种不同的单链抗体组成，分别识别HER2和ErbB3，并融合到重组的人血清白蛋白分子的一侧，以延长体内半衰期。MM-111能够同时结合HER2和HER3形成无活性受体/三聚体复合物，最终导致体外和体内肿瘤细胞生长的抑制。此外，HER3结合scFv后可以阻断NRG与HER3的结合，并且在NRG刺激细胞时增强MM-111的抗增殖作用。然而，MM-111的治疗效果取决于两种受体的同时结合，并且MM-111的相对作用与癌细胞HER2过表达的水平相关。综上所述，研究结果表明MM-111可能对靶向也表达HER3的HER2过表达肿瘤有效。然而Ⅱ期临床试验中，MM-111加用紫杉醇+曲妥珠单抗后未改善无进展生存时间或总生存时间，导致进一步研究被终止。Istiratumab（MM-141）是由美国Merrimack公司开发的靶向ErBB3和胰岛素样生长因子（insulin-like growth factor，IGF）1 受体（IGF1 receptor，IGF1R）的四价双抗，由抗IGF-1R人IgG1抗体组成，重链羧基末端与两个抗HER3 scFv融合。该抗体的开发是基于仅靶向IGF-1R的抗体由于HER3介导的补偿信号传导而导致有效性低下的假设。MM-141可以在抑制NRG与ErbB3结合的同时抑制IGF-1/IGF-2与IGF1R的结合，并阻断下游PI3K/Akt途径信号传导，被证明可以增强化疗药物和mTOR抑制剂的抗肿瘤活性。在转移性胰腺癌相关的Ⅱ期临床试验（NCT02399137）中，MM-141联用化疗药物未能改善疗效，并且血清高IGF-1水平也被认为不是不良预后因素。然而鉴于其靶向广泛的受体谱，或许需要更多的研究来准确了解其在除转移性胰腺癌之外的人类肿瘤治疗中，相对于单特异性抗ErbB3抗体或双重特异性抗ErbB3-EGFR或抗ErbB3-抗HER2抗体的优越性。2.3ADC日本第一三共公司开发的ADCU3-1402（Patritumab deruxtecan，HER3-Dxd）是由裸抗U3-1287（Patritumab）和含有拓扑异构酶Ⅰ抑制剂依喜替康（exatecan，MAAA-1181a，Dxd）的药物接头共价偶联而成，每个抗体连接有8个Dxd。U3-1402的连接子和小分子药物与当下已获批上市的HER2 ADCDS8201一致，不但可以同其裸抗U3-1287一样通过与癌细胞表面的HER3特异性结合抑制HER3激活的信号传导；同时在被高效内吞到癌细胞内并转移到溶酶体后释放出依喜替康，可以诱导DNA损伤和细胞凋亡，具有一定的旁观者杀伤作用。U3-1402的临床试验已进展到Ⅲ期，但其主要研究方向目前并不在HNSCC，而在非小细胞肺癌和乳腺癌方面。鉴于其裸抗U3-1287在HNSCC中表现出来的治疗潜力，有理由相信这一ADC临床候选药物也能在HNSCC治疗领域展现出更多惊喜。此外，Capone等的基于自研抗HER3抗体EV20研发了多个ADC：EV20-Sap、EV20/MMAF、EV20-sss-vc/MMAF以及EV20/NMS-P945。其中，EV20/NMS-P945所偶联的是DNA小凹槽烷化剂NMS-P528，具有良好的终末半衰期和稳定性，并且耐受性良好，对包括HNSCC、前列腺癌、胰腺癌、黑色素瘤、胃癌和卵巢癌的模型都具有一定的治疗活性。2.4其他HER3相关HNSCC治疗策略2.4.1  Pan-HER治疗策略  Sym013由3对协同单抗的混合物组成，分别靶向EGFR、HER2和HER3，目的是防止和抑制任一种EGFR的代偿性激活。Sym013促进受体的降解，诱导ADCC和CDC，在配体存在下起作用并抑制PI3K和胞外信号调节激酶途径的激活。用Sym013在体内和体外针对100多种癌细胞系进行测试，可显著减弱癌细胞增殖并优于参考抗体（西妥昔单抗、曲妥珠单抗和MM-121）的活性。值得一提的是，Sym013可有效抑制化疗和HER靶向治疗耐药模型（例如西妥昔单抗、曲妥珠单抗和T-DM1）的生长。在非小细胞肺癌和HNSCC异种移植物（包括西妥昔单抗耐药模型）中，Sym013与单次或分次放射治疗（放疗）联合使用显示出更好的抗肿瘤作用和延迟再生。临床试验NCT02906670纳入32例既往未接受过EGFR/HER靶向治疗的患者，其中2例HNSCC患者每2周9 mg/kg治疗后病情稳定，1例病情稳定超过20周。但遗憾的是该药物相关的临床试验后因业务原因提前终止。2.4.2  CAR-T治疗策略  LEU-001是由伦敦国王大学开发的T4免疫疗法，包含表达T1E28z的工程自体T细胞，是一种与ErbB家族中包含HER3的几个成员结合的第2代CAR，以及一种嵌合细胞因子受体4αβ。它可将IL-4提供的弱促有丝分裂刺激转化为强而具选择性的生长信号，从而允许T4 T细胞在体外优先扩增和富集。LEU-001在体内对HNSCC细胞系和肿瘤发挥抗肿瘤活性，无明显毒性，目前主要研究方向是用于HNSCC的瘤内治疗。2013年3月，1项开放标签、非随机、剂量递增、单组、安全性的Ⅰ期临床研究（NCT01818323）在英国HNSCC患者中开展。2019年1月在欧盟CAR-T大会上公布的结果显示，15例注射患者中有9例生存率有潜在改善。2.4.3  HER3疫苗治疗策略  目前有2项HER3疫苗的临床试验——NCT0434874和NCT03832855。NCT03832855是名为pING-hHER3FL的研究性癌症疫苗的Ⅰ期临床试验。pING-hHER3FL为环状DNA，可产生全长人HER3，在研究中用作免疫治疗剂靶向已知表达HER3的癌症，包括HNSCC。2.4.4  抗金属蛋白酶制剂治疗策略  人ADAM17抑制抗体D1（A12）是特异性人ADAM17抑制抗体，可在体外和体内抑制EGFR配体和TNFα脱落。ADAM17是金属蛋白酶，也称TNFα转换酶，可将膜结合的TNFα前体释放成可溶形式，可以抑制EGFR、HER2、HER3和HER4多个酪氨酸残基的磷酸化。D1（A12）在体外可显著抑制HNSCC细胞系的增殖，降低了 HNSCC中的促肿瘤信号传导，未来或可作为治疗EGFR TKI耐药HNSCC的有效靶向药物之一。3小结与展望本综述总结了 HNSCC中HER3的作用机制、HER3靶点与HNSCC当下治疗策略的关系，以及靶向HER3或与HER3相关的HNSCC治疗策略。其中大多数与HNSCC中HER3相关的治疗策略都处于临床前开发阶段，同时目前尚无专门针对HER3的治疗方法被批准用于临床。然而，许多上文提及的药物都在针对HNSCC患者的研究中显示出显著的疗效。HER3在治疗获得性耐药和整体HER信号传导中起着至关重要的作用。因此，从HER3作用机制和临床或临床前单一用药的结果而言，同时抑制HER3以及其他RTK（包括EGFR家族成员）可能有助于患者获得更大的临床益处，即单纯的抗HER3单抗治疗策略可以通过与西妥昔单抗、曲妥珠单抗、化疗、放疗、免疫治疗联用，来达到更好的治疗效果。自1986年美国FDA批准第1个治疗性单抗药物以来，靶向药物从适应证探索到技术改进，从临床研究到商业化策略，各个方面日趋成熟。近几年，最令人期待的应当就是ADC。鉴于DS8201在HER2低表达患者中表现出的优异疗效，以及HER3 ADCU3-1402中裸抗U3-1287在HNSCC中表现出的治疗潜力，希望靶向HER3的ADC未来也能在HNSCC治疗中展现出更多的惊喜。目前在HNSCC中的靶向HER3治疗基本都经历了漫长的研发和不断试错的过程，都是来之不易的成果。面向未来，我们还需将研发侧重于：（1）加深对HER3靶点作用机制的认识，如处于研发阶段的抗HER3单抗应尽可能多地尝试与临床一/二线药物联用，或探索治疗获得性耐药的HNSCC难治患者的治疗潜力；（2）探索开发更多革新的技术，如双抗、ADC、使用2种以上不同有效载荷组合的ADC、核素偶联药物等。更大程度扩展可用于治疗HNSCC患者的武器库，有助于实现HNSCC的持久治愈和无复发生存。作者章权综述  瞿爱东审校上海生物制品研究所有限责任公司第一研究室，上海 200051通信作者：瞿爱东，Email: quaidong1@sinopharm.com引用本文：章权, 瞿爱东. 靶向HER3治疗在头颈部鳞状细胞癌中的研究进展 [J]. 国际生物制品学杂志, 2023, 46(6): 381-390.  DOI: 10.3760/cma.j.cn311962-20230220-00018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。

A new study reveals the crucial role of vascular system cells -- known as pericytes -- in the formation of long-term memories of life events -- memories that are lost in diseases such as Alzheimer's disease. Research on long-term memories has largely focused on the role of neurons -- the brain's nerve cells. However, in recent years, scientists are discovering that other cell types are also vital in memory formation and storage. A new study, published in the journal Neuron, reveals the crucial role of vascular system cells -- known as pericytes -- in the formation of long-term memories of life events -- memories that are lost in diseases such as Alzheimer's disease. The research, conducted by New York University neuroscientists, shows that pericytes, which wrap around the capillaries -- the body's small blood vessels -- work in concert with neurons to help ensure that long-term memories are formed. "We now have a firmer understanding of the cellular mechanisms that allow memories to be both formed and stored," says Cristina Alberini, a professor in New York University's Center for Neural Science and the paper's senior author. "It's important because understanding the cooperation among different cell types will help us advance therapeutics aimed at addressing memory-related afflictions." "This work connects important dots between the newly discovered function of pericytes in memory and previous studies showing that pericytes are either lost or malfunction in several neurodegenerative diseases, including Alzheimer's disease and other dementia," explains author Benjamin Bessières, a postdoctoral researcher in NYU's Center for Neural Science. Pericytes help maintain the structural integrity of the capillaries. Specifically, they control the amount of blood flowing in the brain and play a key role in maintaining the barrier that stops pathogens and toxic substances from leaking out of the capillaries and into brain tissue. The discovery, reported in the new Neuron article, of the pericytes' significance in long-term memory emerged because Alberini, Bessières, Kiran Pandey, and their colleagues examined the role of insulin-like growth factor 2 (IGF2) -- a protein that was known to increase following learning in brain regions, such as the hippocampus, and to play a critical role in the formation and storage of memories. They found that IGF2's highest levels in the brain cells of the hippocampus do not come from neurons or glial cells, or other vascular cells, but, rather, from pericytes. IGF2's presence in pericytes, then, raises the following question: How is this linked to memory? The scientists conducted a series of cognitive experiments using mice, comparing behaviors of those with pericytes that produced IGF2 and those that did not. By removing IGF2-producing capacity in some, the researchers could isolate the significance of both pericytes and IGF2 in neurological processes. In these experiments, the mice were subjected to a series of memory tests -- learning to associate a mild foot shock to a specific context or learning to identify objects placed in a new location. Their results showed that production of IGF2 by pericytes in the hippocampus was enhanced by the learning event. More specifically, this increase in pericytic IGF2 took place in response to activity of neurons, revealing a concerted, neuron-pericytic action. In addition, IGF2 produced by pericytes were shown to circle back to influence biological responses of neurons that are critical for memory. "IGF2 produced from pericytes and acting on neurons support the idea that a neurovascular unit regulates neuronal responses as well as functions of the blood barrier and may have repercussions on brain injury and inflammation," notes Pandey, a postdoctoral researcher in NYU's Center for Neural Science. "Cooperation between neurons and pericytes is necessary to assure that long-term memories are formed," observes Alberini. "Our study provides a new view of the biology of memory -- though more research is needed to further understand the roles of pericytes and the vascular system in memory and its diseases." The research of this study also included scientists from Cold Spring Harbor Laboratory and the University of Cambridge. The research was supported by grants from the National Institutes of Health (MH065635), the United Kingdom's Biotechnology and Biological Sciences Research Council (BB/H003312/1) and Medical Research Council (MRC MC_UU_00014/4, MRC_MC_UU_12012/5). Alberini is a founder and equity holder of Ritrova Therapeutics, Inc, a company exploring new treatments for neurodegenerative diseases and neurodevelopmental disorders. The company did not fund this study.