CLEC-2

导读：随着对适应性免疫在细胞和分子水平上的认识，靶向免疫细胞的抗原因其可能提高疫苗效力和/或调节免疫反应质量，同时减少脱靶效应，被证明是开发创新、强效疫苗的成功策略。随着mRNA疫苗的发展，近几年已经探索了几种将包裹mRNA的纳米颗粒递送系统靶向免疫细胞（树突状细胞DC）的方法，DC是最有效的抗原呈递细胞，也是B细胞和T细胞免疫的关键介质，被认为是细胞特异性抗原递送的理想靶标。那么如何设计mRNA疫苗递送系统以靶向免疫细胞呢？2023年11月，GSK团队在Front Immunol期刊发表综述文章：《Straight to the point: targeted mRNA-delivery to immune cells for improved vaccine design》。文章汇总了mRNA定向递送免疫系统的潜在特异性靶点、靶向受体-配体类别以及递送系统的研究进展。一、免疫细胞靶向由于常规疫苗（抗原、灭活病原体）开发周期长（5-10年），针对新发和再发疾病的疫苗开发难度大，科学家们致力于探索新的疫苗平台，最近，mRNA疫苗在设计和疗效方面有较大突破，其之所以能脱颖而出，与以下特性有关：1、安全性：mRNA的非感染性和非整合性避免感染或插入诱变的潜在风险。2、稳定性：mRNA疫苗可通过纳米载体（如LNPs）实现体内递送，使其免于降解、快速摄取和细胞质递送，避免抗载体免疫。3、高产量：由于体外转录反应的高产量，mRNA疫苗具有经济高效、可扩展生产的潜力。4、可修饰性：可进行快速修饰调节半衰期和免疫原性特征，用于个性化治疗或紧急适应新出现的病原体。但同时mRNA疫苗具有以下不足：1、潜在的脱靶效应：肌肉注射后，会有少部分到达血流，最终主要进入肝脏和脾脏，出现脱靶效应。2、非特异性：mRNA-LNPs的给药会诱导中性粒细胞、单核细胞和DCs快速和局部浸润到给药部位及引流淋巴结（LNs），但主要是单核细胞和DCs翻译mRNA并上调关键的共刺激受体（CD80和CD86）和细胞因子产生。3、针对某些蛋白（如刺突蛋白）的抗体反应持久性较短，需要连续给予加强剂量以保持对感染的保护。mRNA选择性靶向免疫细胞因可增强免疫应答、减少疫苗使用剂量、增加保护时长、最大程度减少脱靶及副作用的特性，成为解决上述问题的关键技术。而抗原呈递细胞（APCs），尤其是DCs，因其通过启动幼稚T细胞来启动适应性免疫的独特能力成为mRNA靶向递送的候选细胞。研究表明，即使在低抗原剂量下，DC靶向也能增强和加速特异性抗体反应。使用与特定细胞表面的受体特异性相互作用的配体可实现靶向，不同受体的参与会影响所诱导免疫反应的类型，从而获得特定的结果。DCs可表达多种靶向递送疫苗的受体，包括C型凝集素受体（CLRs）、Toll样受体、清道夫受体、趋化因子受体、补体受体和Fc受体等。DC靶向不仅可提高mRNA疫苗的功效，还能扩大其作用的病原体范围。除DC亚群，参与免疫反应的其他细胞类型（如巨噬细胞）也可作为靶标。图1. APC靶向LNP-mRNA作用机制二、靶细胞下表从起源、分布、特征/功能等方面对多种抗原呈递细胞（APC）进行比较：每种APC都有优点和局限性：与pDCs相比，cDCs在抗原呈递和T细胞活化方面更有效；与巨噬细胞相比，DCs因其拥有卓越的抗原呈递及从外周组织迁移到淋巴结的能力而具有更强引发抗原特异性免疫反应的能力，使其在进行靶向递送方面更具优势。最终靶向何种APC还取决于要靶向的病原体或抗原的特征，多种APCs（如DCs和巨噬细胞）的组合可引发协同效应并产生更强大和多功能的免疫反应。三、靶受体免疫反应的类型和程度取决于捕获抗原的环境，包括用于内化的受体。因此，靶向递送平台的成功取决于配体-受体对的正确选择。3.1  C型凝集素（CLRs）受体3.1.1 CLRs的通性CLRs是由1,000多种蛋白质组成的超家族，因其在各种免疫细胞（包括DCs、巨噬细胞和中性粒细胞等）表面大量表达，并在识别自身和非自身抗原、内化、抗原加工、启动免疫反应、调节免疫细胞间相互作用中发挥作用，被作为靶向抗原和mRNA递送的靶标：CLRs具有一个保守的结构基序-碳水化合物识别结构域（CRD），通过与保守的钙螯合结合位点的相互作用来识别病原体（病毒、细菌和真菌）相关的碳水化合物结构，促进识别和吞噬作用；CLRs信号转导可分为两组：第一组通过基于整合免疫受体酪氨酸的激活（ITAM）样基序（Clec-2、Dectin-1）转导细胞内信号，或通过与携带ITAM的FcRγ接头分子（Dectin-2、Mincle、BDCA-2）结合转导细胞内信号。磷酸化后，ITAM 基序募集并激活 Syk，Syk通过激活转录因子NF-kB复合体的亚基来诱导促炎细胞因子的转录。第二组CLRs在其胞浆末端具有基于免疫受体酪氨酸的抑制（ITIM）基序（例如 MICL）。3.1.2 甘露糖受体甘露糖受体（CD206， MR）为巨噬细胞和DCs表达的内吞受体，介导甘露糖苷（从简单甘露糖到高级甘露聚糖结构）以及岩藻糖和硫酸化LacdiNAc的可溶性配体的交叉呈递，上述特性使基于甘露糖的靶向成为最常见的CLR靶向策略之一。2006年White等人在体外模型中使用甘露糖基化脂质体来增加单核细胞来源的DCs（moDCs）对OVA的摄取。大量报告表明，基于甘露糖的策略通过受体介导的机制增加了免疫细胞中mRNA疫苗的内化和转染。2011年首次报道了MR靶向癌症疫苗的临床试验，但MR靶向mRNA疫苗的临床活性尚不清楚。3.1.3 其他C型凝集素1、DC-SIGN：钙依赖型，存在于人的DCs和巨噬细胞亚群上，可结合高甘露糖基化糖缀合物和含岩藻糖的抗原，通过促进T细胞粘附到DC表面以查找肽抗原的存在来介导DC-T细胞相互作用。DC-SIGN会诱导细胞内信号转导，从而调节其他病原体识别受体PRRs（如TLRs）的信号转导。2、DEC-205（CD205）：在DCs、单核细胞和LCs上表达，也在B细胞、T细胞和NK细胞上低水平表达，具有识别凋亡和坏死信号、参与内吞作用并增加MHC II呈递的功能。大多数DC205靶向依赖于抗体或抗体片段的使用，从而产生有效的DC靶向和增强的抗原交叉呈递，2011年进行了针对抗HIV DEC-205靶向疫苗的临床试验。3、Dectin-1：由DCs、巨噬细胞、单核细胞、中性粒细胞和T细胞亚群表达，能特异性识别具有不同亲和力的可溶性和颗粒性β（1-3）和/或β（1-6）连接葡聚糖，通过肌动蛋白依赖性吞噬作用促进颗粒摄取并通过ITAM样基序参与细胞活化，因可以与CD4+和CD8+T细胞结合并促进增殖被认为是一种共刺激分子。4、Langerin（CD207）：由LCs、真皮DCs和其他DCs亚型表达，已成功使用抗体或小分子糖作为靶向配体在体外进行LC靶向，Wamhoff等人发现了一种Langerin拟糖配体，并使用功能化脂质体证明了其对Langerin+细胞的选择性。Schulze等人用这种Langerin配体在体外选择性地将纳米颗粒（脂质体）靶向人LCs，该配体可用于功能化封装药物、抗原或毒素的纳米颗粒以递送至LCs中。5、DNGR-1（Clec9a）和MGL（Clec10a）：DNGR-1/Clec9a在人cDC1上选择性表达。与该受体的特异性相互作用可促进非人灵长类动物的体液免疫，最近研究发现DNGR-1特异性肽可将纳米颗粒靶向Clec9a+ DC。MGL在人cDC2（CD1c+ DCs）上特异性表达，选择性地结合GalNAc末端和具有不同糖基化谱的粘蛋白-1肽。Heger等人发现，使用Clec10a结合糖肽，可以选择性靶向PBMCs中的CD1c+细胞（cDC2），但未观察到单独的Clec10的配体可诱导CD1c+ DCs的激活或细胞因子分泌。6、hDCIR（Clec4a）：存在于外周血中的CD14+单核细胞、CD15+粒细胞、所有DC亚群（包括pDCs）和B细胞上，T细胞中未发现，使用抗体将抗原靶向DCIR可增加LCs、血液mDCs和pDCs的交叉呈递，并增强体外人细胞中CD8+ T细胞触发。3.2 用于mRNA靶向递送的其他受体1、Toll样受体（TLRs）：由先天免疫系统细胞（如巨噬细胞和DCs）、适应性免疫细胞亚群表达，通过识别病原体相关分子模式PAMPs在先天免疫系统中发挥关键作用，研究使用Pam3CSK4（一种TLR-2激动剂）作为靶向配体将纳米颗粒靶向DCs。2、X-C基序趋化因子受体1（XCR1）：可识别XCL1的趋化因子受体，在cDC1上选择性表达。Fossum等人研究Clec9a、DEC-205和XCR-1作为靶标，使用编码与抗原融合的单链可变片段（scVf）的DNA疫苗注射到小鼠体内，发现靶向XCR-1导致脾脏和肺中IFN-γ+CD8+ T细胞反应增强，细胞毒性更强，尽管Clec9a和XCR1都是cDC1特异性的，但导致不同的结果，因此不仅细胞亚型，受体本身也决定了靶向的结果和疗效。表1 免疫细胞靶向案例、靶向策略和结果四、纳米颗粒作为靶向mRNA递送载体将mRNA与载体结合以保护其免于降解并实现胞内递送。目前输送系统简单分为病毒和非病毒载体。病毒载体利用其自然进化的能力将遗传物质有效地转移到细胞中，实现高效率翻译，但其自身的趋向性并不总是满足治疗需求，且诱导的免疫反应可转化为反应原性损害治疗效果。目前纳米颗粒（特别是脂质纳米颗粒LNP）为首选的非病毒载体，提供了定制其特性以优化其作为转染剂性能的可能性。脂质纳米颗粒（LNPs）已从脂质体和脂质复合体进化为更有效的mRNA载体，出现了可电离脂质，其优势在于：1、可电离脂质在酸性pH值下带正电，在生理pH值下带中性电，该特性大大改善了永久性阳离子脂质的固有缺点，如耐受性差和细胞毒性；2、可电离脂质在内体中酸化后，胺基团被质子化并促进氯离子转运以平衡膜电荷和渗透压，直到膜被破坏并将遗传物质递送到胞质溶胶中；3、通过增加可电离脂质疏水尾部的不饱和度以及调整其pKa，可增加内体逃逸，增强疫苗效力；4、可电离脂质能实现高速率mRNA包封，由于生产过程中水相的pH值较低，可电离脂质带正电，从而促进了与带负电荷的mRNA骨架的相互作用。LNPs另一个成分是聚乙二醇化脂质，由亲水性PEG聚合物与疏水脂质偶联而成。聚乙二醇化脂质可阻止调理素结合，增加LNP循环时间并防止颗粒融合。通过改变PEG脂质锚定长度，可调整其从LNP表面的脱落速率，对促进细胞摄取和内体逃逸至关重要。另外LNPs中的磷脂和胆固醇有助于mRNA包封及增强稳定性。对LNPs脂质成分和/或比例进行多种修饰，实现其优先在特定器官中积累的特性，Goswami等人表明，甘露糖化胆固醇可改善抗RSV自扩增mRNA疫苗（SAM）的内化和效力，一些MR靶向siRNA的例子（配体直接连接到siRNA 或siRNA包封颗粒）也被报道。图2 LNP 结构、组成和靶向配体加入策略五、结论靶向先天免疫相关细胞上的特异性受体可以产生针对疫苗量身定制的更强大、更持久的免疫反应，不同先天免疫细胞亚群的联合靶向策略更令人期待，因为它们在免疫反应中起着独特而核心的作用。如巨噬细胞驱动炎症反应，而树突状细胞在抗原呈递给T细胞中起关键作用，若同时靶向两种细胞类型可能有助于启动改善的抗原特异性免疫反应。需要进一步的研究来识别不同细胞类型中潜在的共同关键受体，或配制具有多种靶向配体组合的LNPs。对于开发RNA递送载体，应在载体配方步骤中考虑组分的相容性，以及保持有效的内体逃逸和充分的多价配体展示的必要性。eGFP mRNA和mCherry mRNA在293T细胞中实现高表达参考文献[1] Clemente B, Denis M, Silveira CP, Schiavetti F, Brazzoli M, Stranges D. Straight to the point: targeted mRNA-delivery to immune cells for improved vaccine design. Front Immunol. 2023 Nov 27;14:1294929. doi: 10.3389/fimmu.2023.1294929.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。

-- Provides Update on ACTIV-4 Host Tissue Trial -- SOUTH SAN FRANCISCO, Calif., Oct. 11, 2023 /PRNewswire/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) today announced an upcoming oral presentation highlighting data from the FOCUS Phase 3 clinical trial of fostamatinib in hospitalized COVID-19 patients without respiratory failure who have certain high-risk prognostic factors at IDWeek 2023 being held October 11-15, 2023, in Boston, MA and provided an update on the ACTIV-4 Host Tissue trial of fostamatinib in hospitalized patients with COVID-19. "From the outset of the COVID-19 pandemic, we were hopeful of making an impact. However, our focus remains on our hematology-oncology commercial and clinical portfolio," said Raul Rodriguez, Rigel's president and CEO. "As we have previously reported, we do not plan to submit an Emergency Use Authorization or a supplemental New Drug Application given the end of the federal COVID-19 Public Health Emergency in May 2023, and based on feedback from the FDA, US Department of Defense and other advisors regarding the program's regulatory requirements, costs, timeline and potential for success." Details of the oral presentation at IDWeek 2023 are as follows: Abstract #: 88 Title: Fostamatinib for the Treatment of Hospitalized Patients With COVID-19 Who Required Oxygen Supplementation: Results of a Phase 3 Trial Presenter: Dr. Deepa Gotur, MD, FCCP, FCCM, Associate Professor Clinical Medicine, Weill Cornell Medical College and Houston Methodist Hospital, Houston, TX Session Name: Clinical Trials Date: Thursday, October 12, 2023 Presentation Time: 11:15 – 11:30AM ET Location: 102 AB, Boston Convention and Exhibition Center This presentation reports severe COVID-19 is linked to hyperactivation of the host immune response involving signaling through multiple spleen tyrosine kinase (SYK) pathways. Fostamatinib is an orally administered potent and selective inhibitor of SYK that has been approved in the US, Canada, Japan, and Europe for the treatment of chronic immune thrombocytopenia (ITP). The FOCUS Phase 3 clinical trial was a double-blind, randomized, placebo-controlled trial of fostamatinib in adults hospitalized for COVID-19 who required oxygen supplementation (NCT04629703). Patients were randomly assigned 1:1 to receive fostamatinib (150 mg BID administered orally) or placebo for 14 days. All patients additionally received standard of care at their hospital. The primary endpoint was days on oxygen (days 1-29). A total of 280 patients underwent randomization (with 141 assigned to fostamatinib and 139 to placebo). The primary endpoint was met; those who received fostamatinib had lower mean days on oxygen than those who received placebo (4.8 vs. 7.6 days, p=0.0136). Fostamatinib showed significance or trend towards significance in all secondary endpoints of reducing mortality and morbidity compared to placebo. The mean change in the 8-point ordinal score from baseline to the average of Day 5 to 15 was significantly improved in patients who received fostamatinib vs. placebo (p=0.0092). Furthermore, 6 patients were enrolled with baseline ordinal score of 6 (3 in each group). All patients in the fostamatinib group survived, and all in the placebo group died by Day 30. A significantly higher proportion of patients who received fostamatinib were discharged from the hospital by Day 15 compared to placebo (p=0.0029). Significantly more patients were alive and oxygen-free by Day 29 and Day 60 with fostamatinib treatment in comparison to placebo (p=0.0213 and p=0.0271, respectively). Treatment-emergent adverse events were consistent with previous studies and were similar between the 2 groups. The addition of fostamatinib to standard of care treatment resulted in significantly fewer days on oxygen, an improved 8-point ordinal scale score, and significantly more patients alive and oxygen-free by Day 60 compared to placebo in patients with COVID-19 requiring hospitalization and supplemental oxygen. ACTIV-4 Host Tissue (NECTAR) Trial Update On September 26, 2023, the Data and Safety Monitoring Board (DSMB) recommended that the fostamatinib study arm of the ACTIV-4 Host Tissue (NECTAR) platform cease enrollment. Based on their review of a conditional power analysis, the DSMB determined that there was an extremely low likelihood of fostamatinib providing benefits related to the primary outcome (Oxygen Free Days) or other secondary outcomes in patients hospitalized and on oxygen therapy for COVID-19. No safety concerns were identified. The National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health, concurs with the DSMB's recommendations and has asked the trial investigators to cease enrollment, complete follow-up for participants already enrolled, and complete study closeout. The full study data will be analyzed and disseminated as previously planned. About COVID-19 & SYK Inhibition COVID-19 is the infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). SARS-CoV-2 primarily infects the upper and lower respiratory tract and can lead to acute respiratory distress syndrome (ARDS). Additionally, some patients develop other organ dysfunction including myocardial injury, acute kidney injury, shock resulting in endothelial dysfunction and subsequently micro and macrovascular thrombosis.1 Much of the underlying pathology of SARS-CoV-2 is thought to be secondary to a hyperinflammatory immune response associated with increased risk of thrombosis.2 SYK is involved in the intracellular signaling pathways of many different immune cells. Therefore, SYK inhibition may improve outcomes in patients with COVID-19 via inhibition of key Fc gamma receptor (FcγR) and c-type lectin receptor (CLR) mediated drivers of pathology such as pro-inflammatory cytokine release by monocytes and macrophages, production of neutrophil extracellular traps (NETs) by neutrophils, and platelet aggregation.3,4,5,6 Furthermore, SYK inhibition in neutrophils and platelets may lead to decreased thrombo-inflammation, alleviating organ dysfunction in critically ill patients with COVID-19. About Rigel Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) is a biotechnology company dedicated to discovering, developing and providing novel therapies that significantly improve the lives of patients with hematologic disorders and cancer. Founded in 1996, Rigel is based in South San Francisco, California. For more information on Rigel, the Company's marketed products and pipeline of potential products, visit . Berlin DA, Gulick RM, and Martinez FJ. Severe Covid-19. N Engl J Med 2020. DOI: Becker RC. COVID-19 Update: COVID-19 associated coagulopathy. Journal of Thrombosis and Thrombolysis May 15, 2020. DOI: Hoepel W et al. High titers and low fucosylation of early human anti–SARS-CoV-2 IgG promote inflammation by alveolar macrophages. Science Translational Medicine 02 Jun 2021. DOI: Sung P-S and Hsieh S-L. CLEC2 and CLEC5A: Pathogenic Host Factors in Acute Viral Infections. Frontiers in Immunology December 6, 2019. DOI: Bye AP et al. Aberrant glycosylation of anti-SARS-CoV-2 IgG is a pro-thrombotic stimulus for platelets. BioRxiv March 26, 2021. DOI: Strich J et al. Fostamatinib Inhibits Neutrophils Extracellular Traps Induced by COVID-19 Patient Plasma: A Potential Therapeutic. Journal of Infectious Disease March 15, 2021. DOI: Forward-Looking Statements This release contains forward-looking statements relating to, among other things, our expectations related to the role of fostamatinib in the treatment of patients with COVID-19 and in future pandemics, including next steps in collaboration with Rigel's partner, the U.S. Department of Defense, and the timing and results of the ACTIV-4 study. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "potential", "may", "expects", and similar expressions are intended to identify these forward-looking statements. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on Rigel's current beliefs, expectations, and assumptions regarding the future of our business, future plans and strategies, projections, anticipated events and trends, the economy and other future conditions, and hence they inherently involve significant risks, uncertainties and changes in circumstances that are difficult to predict and many of which are outside of our control. Therefore, you should not rely on any of these forward-looking statements. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks detailed from time to time in Rigel's reports filed with the Securities and Exchange Commission, including its Quarterly Report on Form 10-Q for the quarter ended June 30, 2023, and subsequent filings. Any forward-looking statement made by us in this press release is based only on information currently available to us and speaks only as of the date on which it is made. Rigel does not undertake any obligation to update forward-looking statements and expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein, except as required by law. Investors & Media Contacts: Investors: Rigel Pharmaceuticals, Inc.  650.624.1232 ir@rigel.com Media: David Rosen Argot Partners Phone: 212.600.1902 Email: david.rosen@argotpartners.com Company Codes: NASDAQ-NMS:RIGL

FDA review ongoing for olutasidenib NDA; preparations underway for potential launch Third quarter TAVALISSE® net product sales of $19.2 million and total revenues of $22.4 million Conference call and webcast scheduled today at 4:30 p.m. Eastern Time SOUTH SAN FRANCISCO, Calif., Nov. 3, 2022 /PRNewswire/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) today reported financial results for the third quarter ended September 30, 2022, including sales of TAVALISSE® (fostamatinib disodium hexahydrate) tablets for the treatment of adults with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment. "We are excited to have several poster presentations at ASH that showcase our hematology-oncology portfolio. In particular, updated data from the Phase 2 registrational study of olutasidenib in patients with mIDH1 relapsed or refractory acute myeloid leukemia demonstrate durable remissions, which we believe truly differentiates olutasidenib as a potential market leading therapy," said Raul Rodriguez, Rigel's president and CEO. "In addition, during the third quarter of 2022, we made meaningful progress to position the company for the potential launch of olutasidenib and to drive growth in TAVALISSE ITP sales." Business Update In the third quarter of 2022, TAVALISSE net product sales were $19.2 million, an increase of 20% compared to the same period of 2021. In August, Rigel announced an exclusive license agreement with Forma Therapeutics, Inc. (Forma) to develop, manufacture and commercialize olutasidenib, an investigational, oral, small molecule inhibitor of mutant isocitrate dehydrogenase-1 (mIDH1) for the treatment of relapsed/refractory acute myeloid leukemia (R/R AML) and other malignancies. Forma's New Drug Application (NDA) for olutasidenib is under review by the U.S. Food and Drug Administration (FDA) with a Prescription Drug User Fee Act (PDUFA) target action date of February 15, 2023. Today, Rigel announced five poster presentations at the 64th ASH Annual Meeting, including updated data from the interim analysis of 147 efficacy evaluable patients with mIDH1 R/R AML who received olutasidenib monotherapy 150 mg twice daily. Results from the interim analysis of patients with mIDH1 R/R AML demonstrated a 35% CR+CRh* rate with a median duration of 25.9 months. The abstract concluded that the observed activity is clinically meaningful and represents a potential therapeutic advance in the treatment of this patient population. This week, Rigel announced top-line results from the FOCUS Phase 3 clinical trial of fostamatinib in high-risk hospitalized COVID-19 patients. While the trial approached but did not meet statistical significance (p=0.0603) in the primary efficacy endpoint of the number of days on oxygen through Day 29, all prespecified secondary endpoints in the study numerically favored fostamatinib over placebo, including mortality, time to sustained recovery, change in ordinal scale assessment, and number of days in the ICU. The Company is evaluating the opportunity and next steps in collaboration with its partner, the U.S. Department of Defense. In October, Rigel announced that it does not expect to file a supplemental NDA for fostamatinib for the treatment of patients with warm autoimmune hemolytic anemia (wAIHA) based on guidance from the FDA's review of the Company's re-analysis of data from the FORWARD Phase 3 trial. Rigel will continue to explore its options for the wAIHA program in relation to its complete portfolio of development opportunities. In October, Rigel also announced a 16% reduction in its workforce, resulting in the elimination of 30 positions primarily in development and administration. Financial Update For the third quarter of 2022, Rigel reported a net loss of $19.0 million, or $0.11 per basic and diluted share, compared to a net loss of $21.0 million, or $0.12 per basic and diluted share, for the same period of 2021. For the third quarter of 2022, total revenues were $22.4 million, consisting of $19.2 million in TAVALISSE net product sales, $0.7 million in contract revenues from collaborations and $2.5 million in government contract revenue. TAVALISSE net product sales of $19.2 million increased by 20%, compared to $16.0 million in the third quarter of 2021. Contract revenues from collaborations during the third quarter of 2022 consisted primarily of revenue from Grifols related to the delivery of fostamatinib supply, performance of certain research and development services pursuant to the collaboration agreement and royalty revenue. Government contract revenue for the third quarter of 2022 was related to the income recognized pursuant to the agreement with the U.S. Department of Defense (DOD) to support Rigel's ongoing Phase 3 clinical trial of fostamatinib in hospitalized patients with COVID-19. For the third quarter of 2022, total costs and expenses were $40.8 million, compared to $41.3 million for the same period of 2021. The decrease in costs and expenses was primarily due to a decrease in research and development costs related to the Phase 3 clinical trial for wAIHA, the Phase 3 clinical trial in high-risk hospitalized patients with COVID-19 and the IRAK 1/4 inhibitor program. These decreases were partially offset by increased personnel related costs and commercial activities. For the nine months ended September 30, 2022, Rigel reported a net loss of $60.0 million, or $0.35 per basic and diluted share, compared to a net income of $4.7 million, or $0.03 per basic and diluted share, for the same period of 2021. For the nine months ended September 30, 2022, total revenues were $69.0 million, consisting of $53.9 million in TAVALISSE net product sales, $12.5 million in contract revenues from collaborations and $2.5 million in government contract revenue. TAVALISSE net product sales of $53.9 million increased by 19% compared to $45.4 million in the same period of 2021. Contract revenues from collaborations for the nine months ended September 30, 2022, consisted of $7.6 million in revenue from Kissei primarily related to a milestone payment and delivery of fostamatinib supply, $2.0 million in revenue related to the license agreement with Knight, $2.4 million in revenue from Grifols related to the delivery of fostamatinib supply, performance of certain research and development services pursuant to the collaboration agreement and royalty revenue, and $0.5 million in revenue related to the license agreement with Eli Lilly. Government contract revenue for the nine months ended September 30, 2022, was related to the income recognized pursuant to the agreement with the DOD as mentioned above. For the nine months ended September 30, 2022, total costs and expenses were $126.6 million, compared to $119.9 million for the same period of 2021. The increase in costs and expenses was primarily due to increased personnel costs from the sales force expansion, increased commercial-related activities, and increased research and development costs for the IRAK1/4 inhibitor program. These increases were partially offset by decreased research and development costs related to the Phase 3 clinical trial for wAIHA and the ongoing Phase 3 clinical trial in high-risk hospitalized patients with COVID-19. As of September 30, 2022, Rigel had cash, cash equivalents and short-term investments of $81.6 million, compared to $125.0 million as of December 31, 2021. Conference Call and Webcast with Slides Today at 4:30pm Eastern Time Rigel will host a live conference call and webcast today at 4:30 p.m. Eastern Time (1:30 p.m. Pacific Time) to discuss financial results and provide an update on the business. Participants can access the live conference call by dialing (877) 407-3088 (domestic) or (201) 389-0927 (international). The conference call will also be webcast live and can be accessed from the Investor Relations section of the company's website at . The webcast will be archived and available for replay after the call via the Rigel website. About ITP In patients with ITP (immune thrombocytopenia), the immune system attacks and destroys the body's own blood platelets, which play an active role in blood clotting and healing. Common symptoms of ITP are excessive bruising and bleeding. People suffering with chronic ITP may live with an increased risk of severe bleeding events that can result in serious medical complications or even death. Current therapies for ITP include steroids, blood platelet production boosters (TPO-RAs), and splenectomy. However, not all patients respond to existing therapies. As a result, there remains a significant medical need for additional treatment options for patients with ITP. About AML Acute myeloid leukemia (AML) is a cancer that starts in a person's bone marrow but often quickly moves into the blood. AML develops from immature blood cells, known as myeloid cells, that are supposed to mature into white blood cells. However, the diseased myeloid cells do not function properly. They instead multiply rapidly, which causes normal blood cell production to fail. AML occurs primarily in adults and accounts for about 1 percent of all adult cancers. The American Cancer Society estimates that in the United States alone, there will be about 20,050 new cases, most in adults, in 2022.1 Relapsed AML affects about half of all patients who, following treatment and remission, experience a return of leukemia cells in the bone marrow.2 Refractory AML, which affects between 10 and 40 percent of newly diagnosed patients, occurs when a patient fails to achieve remission even after intensive treatment.3 About AIHA Autoimmune hemolytic anemia (AIHA) is a rare, serious blood disorder in which the immune system produces antibodies that lead to the destruction of the body's own red blood cells. Warm antibody AIHA (wAIHA), which is the most common form of AIHA, is characterized by the presence of antibodies that react with the red blood cell surface at body temperature. wAIHA affects approximately 36,000 adult patients in the U.S.4 and can be a severe, debilitating disease. To date, there are no disease-targeted therapies approved for wAIHA, despite the unmet medical need that exists for these patients. About COVID-19 & SYK Inhibition COVID-19 is the infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). SARS-CoV-2 primarily infects the upper and lower respiratory tract and can lead to acute respiratory distress syndrome (ARDS). Additionally, some patients develop other organ dysfunction including myocardial injury, acute kidney injury, shock resulting in endothelial dysfunction and subsequently micro and macrovascular thrombosis.5 Much of the underlying pathology of SARS-CoV-2 is thought to be secondary to a hyperinflammatory immune response associated with increased risk of thrombosis.6 SYK is involved in the intracellular signaling pathways of many different immune cells. Therefore, SYK inhibition may improve outcomes in patients with COVID-19 via inhibition of key Fc gamma receptor (FcγR) and c-type lectin receptor (CLR) mediated drivers of pathology such as pro-inflammatory cytokine release by monocytes and macrophages, production of neutrophil extracellular traps (NETs) by neutrophils, and platelet aggregation.7,8,9,10 Furthermore, SYK inhibition in neutrophils and platelets may lead to decreased thrombo-inflammation, alleviating organ dysfunction in critically ill patients with COVID-19. About TAVALISSE Indication TAVALISSE® (fostamatinib disodium hexahydrate) tablets is indicated for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment. Important Safety Information Warnings and Precautions Hypertension can occur with TAVALISSE treatment. Patients with pre-existing hypertension may be more susceptible to the hypertensive effects. Monitor blood pressure every 2 weeks until stable, then monthly, and adjust or initiate antihypertensive therapy for blood pressure control maintenance during therapy. If increased blood pressure persists, TAVALISSE interruption, reduction, or discontinuation may be required. Elevated liver function tests (LFTs), mainly ALT and AST, can occur with TAVALISSE. Monitor LFTs monthly during treatment. If ALT or AST increase to ≥3 x upper limit of normal, manage hepatotoxicity using TAVALISSE interruption, reduction, or discontinuation. Diarrhea occurred in 31% of patients and severe diarrhea occurred in 1% of patients treated with TAVALISSE. Monitor patients for the development of diarrhea and manage using supportive care measures early after the onset of symptoms. If diarrhea becomes severe (≥Grade 3), interrupt, reduce dose or discontinue TAVALISSE. Neutropenia occurred in 6% of patients treated with TAVALISSE; febrile neutropenia occurred in 1% of patients. Monitor the ANC monthly and for infection during treatment. Manage toxicity with TAVALISSE interruption, reduction, or discontinuation. TAVALISSE can cause fetal harm when administered to pregnant women. Advise pregnant women the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment and for at least 1 month after the last dose. Verify pregnancy status prior to initiating TAVALISSE. It is unknown if TAVALISSE or its metabolite is present in human milk. Because of the potential for serious adverse reactions in a breastfed child, advise a lactating woman not to breastfeed during TAVALISSE treatment and for at least 1 month after the last dose. Drug Interactions Concomitant use of TAVALISSE with strong CYP3A4 inhibitors increases exposure to the major active metabolite of TAVALISSE (R406), which may increase the risk of adverse reactions. Monitor for toxicities that may require a reduction in TAVALISSE dose. It is not recommended to use TAVALISSE with strong CYP3A4 inducers, as concomitant use reduces exposure to R406. Concomitant use of TAVALISSE may increase concentrations of some CYP3A4 substrate drugs and may require a dose reduction of the CYP3A4 substrate drug. Concomitant use of TAVALISSE may increase concentrations of BCRP substrate drugs (eg, rosuvastatin) and P-Glycoprotein (P-gp) substrate drugs (eg, digoxin), which may require a dose reduction of the BCRP and P-gp substrate drug. Adverse Reactions Serious adverse drug reactions in the ITP double-blind studies were febrile neutropenia, diarrhea, pneumonia, and hypertensive crisis, which occurred in 1% of TAVALISSE patients. In addition, severe adverse reactions occurred including dyspnea and hypertension (both 2%), neutropenia, arthralgia, chest pain, diarrhea, dizziness, nephrolithiasis, pain in extremity, toothache, syncope, and hypoxia (all 1%). Common adverse reactions (≥5% and more common than placebo) from FIT-1 and FIT-2 included: diarrhea, hypertension, nausea, dizziness, ALT and AST increased, respiratory infection, rash, abdominal pain, fatigue, chest pain, and neutropenia. Please see for full Prescribing Information. To report side effects of prescription drugs to the FDA, visit or call 1-800-FDA-1088 (800-332-1088). TAVALISSE and TAVLESSE are registered trademarks of Rigel Pharmaceuticals, Inc. About Rigel Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) is a biotechnology company dedicated to discovering, developing and providing novel small molecule drugs that significantly improve the lives of patients with hematologic disorders, cancer, and rare immune diseases. Founded in 1996, Rigel is based in South San Francisco, California. For more information on Rigel, the Company's marketed product and pipeline of potential products, visit . The American Cancer Society. Key statistics for acute myeloid leukemia (AML). Revised January 12, 2022. Accessed Aug. 1, 2022 at . Leukaemia Care. (2019). Relapse in Acute Myeloid Leukaemia (AML). Version 3. Reviewed October 2021. Accessed Dec 2, 2021 at . Thol F, Schlenk RF, Heuser M, Ganser A. How I treat refractory and early relapsed acute myeloid leukemia. Blood. 2015 Jul 16;126(3):319-27. Doi: . Epub 2015 Apr 7. PMID: 25852056 Prevalence: A. Zanella, et al, haematologica 2014; 99(10); % Warm AIHA: T. Kalfa; Hematology Am Soc Hematol Educ Program. 2016 Dec 2; 2016(1): 690–697 Berlin DA, Gulick RM, and Martinez FJ. Severe Covid-19. N Engl J Med 2020. DOI: Becker RC. COVID-19 Update: COVID-19 associated coagulopathy. Journal of Thrombosis and Thrombolysis May 15, 2020. DOI: Hoepel W et al. High titers and low fucosylation of early human anti–SARS-CoV-2 IgG promote inflammation by alveolar macrophages. Science Translational Medicine 02 Jun 2021. DOI: Sung P-S and Hsieh S-L. CLEC2 and CLEC5A: Pathogenic Host Factors in Acute Viral Infections. Frontiers in Immunology December 6, 2019. DOI: Strich J et al. Fostamatinib Inhibits Neutrophils Extracellular Traps Induced by COVID-19 Patient Plasma: A Potential Therapeutic. Journal of Infectious Disease March 15, 2021. DOI: Bye AP et al. Aberrant glycosylation of anti-SARS-CoV-2 IgG is a pro-thrombotic stimulus for platelets. BioRxiv March 26, 2021. DOI: Forward-Looking Statements This release contains forward-looking statements relating to, among other things, our expectations related to the potential and market opportunity of olutasidenib; our wAIHA program; and the opportunity and next steps in collaboration with Rigel's partner, the U.S. Department of Defense. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "potential", "may", "expects", and similar expressions are intended to identify these forward-looking statements. These forward-looking statements are based on Rigel's current expectations and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, those risks and uncertainties associated with the commercialization and marketing of TAVALISSE; risks that the FDA, European Medicines Agency or other regulatory authorities may make adverse decisions regarding fostamatinib or olutasidenib; risks that our clinical trials may not be predictive of real-world results or of results in subsequent clinical trials; the availability of resources to develop, manufacture and commercialize our product candidates; market competition; and those other risks detailed from time to time in Rigel's reports filed with the Securities and Exchange Commission, including its Quarterly Report on Form 10-Q for the quarter ended June 30, 2022 and subsequent filings. Rigel does not undertake any obligation to update forward-looking statements and expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein, except as required by law. Contact for Investors & Media: Investors: Rigel Pharmaceuticals, Inc. 650.624.1232 [email protected] Media: David Rosen Argot Partners 212.600.1902 [email protected] SOURCE Rigel Pharmaceuticals, Inc.