Celiac Disease

Topas Therapeutics, a small German biotech company attempting to quell overactive immune systems, has revealed the first data from a study of its “tolerance induction” therapy for celiac disease. The results, to be presented at the Digestive Disease Week conference on Monday, come more than six months after Topas first declared success in the study via a press release , without divulging any data. The company discussed the therapy and shared the data with Endpoints News in an exclusive interview ahead of the conference, though many questions remain about the results. The 38-person trial focused on the safety of the company’s experimental nanoparticle treatment over seven weeks, its ability to steer immune cells toward a less inflammatory state, and patient-reported changes in gastrointestinal symptoms. Topas executives told Endpoints that the therapy was successful against those goals, even though granular data on safety and patient outcomes was missing from the presentation. They conceded that bigger and longer studies are still needed, but added that any relief from celiac disease would be a breakthrough. “There is both very much a medical need and big commercial opportunity in celiac,” Topas CEO Hugo Fry told Endpoints. Celiac disease is caused by an unwanted immune reaction to gluten, which is abundant in food. There’s no treatment or cure for the condition that, by some estimates, may affect as many as 1 in 100 people. Despite that, there are relatively few drug developers working on treatments. Topas is one of three companies, along with Anokion and Takeda, developing a potential immune tolerizing therapy in a Phase 2 study. Rather than merely tamping down on inflammation, the efforts aim to retrain the immune system to ignore triggers like gluten. “Tolerization is at that disease-modifying, almost curative end of the spectrum,” Fry said. It aims to do so by presenting nanoparticles decorated with tidbits of peptides that resemble the problematic parts of proteins that set off the immune system, known as antigens. For the celiac therapy, dubbed TPM502, the company uses three nanoparticles, each with a different antigenic peptide from the gluten protein. In many ways, the goal is opposite to that of a vaccine, which presents antigens to build the body’s reaction and create an immune response. Instead, Topas’ infused nanoparticles target specific cells in the liver that serve as a calming zone for T cells, where they learn to live peacefully alongside antigens that don’t warrant being attacked. “That’s the body’s natural hub of induced tolerization,” Fry said. “And it pushes them through that natural route.” Celiac was a good place to start looking for signals that the tolerization approach was working because doctors can easily provoke the immune system to flare up by having participants consume gluten, said Topas chief medical officer Cristina de Min. The company tested four doses of its nanoparticle therapy, ranging from 0.72 micromolar to 7.2 micromolar, in 26 patients. The other 12 patients got a placebo. Participants got the drug or placebo on day 1 and day 15 of the study and then consumed gluten a week later. De Min said that “the drug was remarkably safe,” largely resulting in side effects that resemble gluten consumption in celiac disease, including headache, pain, nausea and vomiting in 27 patients. But the company didn’t break this safety data down by side effect, or between participants who got the drug versus placebo. The company also said that there were three “grade 3” adverse events, the second highest severity, but didn’t say what they were. To get an idea of whether the treatment was working, Topas measured the release of the inflammatory immune protein IL-2 in response to being “challenged” with gluten. Only the highest dose of the therapy resulted in a significant decrease in IL-2 release. But when studying the gene expression of T cells before and after the therapy, the company found that all dose levels helped turn on genes that tamped down on inflammation and reduced genes that promoted inflammation. Topas also asked patients to rate their gastrointestinal symptoms before and after the treatment. The company said that people who got higher doses of the therapy had reduced symptoms, but the presentation was light on specific details. Topas emphasized that the study was not designed to test for efficacy. Another major caveat was the study’s strict inclusion criteria. Topas screened 391 people and recruited only one-tenth of them. Many prospective participants were excluded because they didn’t produce high enough levels of IL-2 in response to gluten consumption. “We wanted to make sure that only patients with measurable response would be involved,” de Min said. Even more patients were excluded because they didn’t have the certain immune system genotype that Topas focused on in this study. Topas is planning a Phase 2b study that will include a broader range of immune genotypes, accounting for 85% to 90% of people with celiac disease. Topas also wants to develop a tolerization therapy for type 1 diabetes, Fry said. But doing so will require more funding, and Fry is setting out to raise a €70 million Series D round. The company is currently funded through 2026 and isn’t planning to start a new study before then, he said.

Though the trial missed its primary endpoint, Immunic pointed to other positive results from the study to suggest that IMU-838 could succeed in phase 3.\n Immunic’s lead oral small molecule has failed to hit the primary endpoint of a phase 2 trial in patients with progressive multiple sclerosis (PMS), but the New York biotech is pointing to other measures from the study as reason to continue developing the asset.Vidofludimus calcium, called IMU-838 by Immunic, showed only a “modest benefit” of 5% over placebo at improving the yearly rate of percent brain volume change in patients with PMS after the approximately two-year treatment period, Immunic said in an April 30 press release. This measure of brain volume change is the primary endpoint of the still-ongoing phase 2 Calliper trial, which has enrolled 467 patients with PMS. The treatment period followed patients for about 120 weeks, while an open-label extension will continue for up to eight years.The company did not disclose the statistical significance of the result, but a spokesperson confirmed that the trial missed its primary goal.During an April 30 webinar about the top-line results, Immunic CEO Daniel Vitt, Ph.D., dismissed the primary endpoint, saying the measure had fallen behind current scientific advancements.\"Nobody should care at all about whole brain volume change anymore,\" Vitt said. \"This is a little bit of a leftover of our design of a study we did five years ago.\"Though IMU-838 had a marginal effect on reducing whole brain volume loss, patients receiving the drug candidate did see a 20% reduction in loss of the thalamus, Immunic said. \"Change in thalamic volume is considered a more sensitive MRI atrophy marker,\" Immunic said in the release. \"Thalamic atrophy is prevalent in PMS and data has shown strong associations with clinical disability progression.\"Daily oral 45-mg doses of IMU-838 also reduced the risk of a patient experiencing an event that worsened their disability for at least 24 weeks by 20% compared to placebo, as measured by the Expanded Disability Status Scale (EDSS) score, Immunic reported. This figure jumped to 30% when focusing on the subset of patients with primary progressive multiple sclerosis (PPMS), whose disease did not start with the more common relapsing MS (RMS).The time to 24-week confirmed disability worsening based on EDSS is a secondary endpoint of the trial. Immunic did not disclose detailed data in its communications about the top-line results. Results for another secondary endpoint, an MRI measure of change in brain parenchymal fraction, have also not been disclosed yet.\"We ourselves have not seen all data from all endpoints yet and we will continue to receive them over the next weeks and months to come,\" Vitt said in the webinar.The frequency of adverse events in the group of patients receiving treatment was similar to the rate in the placebo group, according to the company\'s release.“We are particularly thrilled to see such a clinically meaningful effect in the PPMS population,” Vitt said in the release, noting “the relative risk of 24-week confirmed disability worsening events” would be the primary endpoint of a potential future phase 3 study.“We look forward to discussing these results with healthcare authorities to determine appropriate next steps for vidofludimus calcium in PMS,” Vitt added. Analysts from William Blair wrote April 30 that \"with usual cross-trial comparison caveats, in our view, vidofludimus calcium demonstrated a competitive risk/benefit profile\" compared to Genentech\'s Ocrevus (ocrelizumab), Novartis\' Mayzent (siponimod) and Sanofi\'s experimental tolebrutinib.\"The FDA appears to be focused on confirmed disability worsening endpoints where vidofludimus compares well in the PPMS population,\" the analysts wrote.Immunic\'s stock price dropped sharply after the data reveal, from $1.41 per share in the evening of April 29 to 99 cents per share by 2 p.m. EDT on April 30.William Blair analysts attributed this stock drop to concerns about Immunic\'s ability to fund a phase 3 trial for IMU-838; the company reported $35.7 million in cash and cash equivalents as of March 31, which is expected to fund the company through the third quarter of this year.\"We acknowledge the financing overhang is material and Immunic will likely need a partner and/or additional capital to fund future phase III studies,\" the analysts wrote.Most patients with MS have relapsing MS, where symptoms like numbness, fatigue, vision changes and brain fog periodically flare up. In progressive MS, these symptoms instead gradually worsen over time; flare-ups may still happen but are less common. Relapsing MS can develop into progressive MS over time, called secondary progressive MS, but about 10% of MS patients are diagnosed with primary progressive MS without first having any relapsing symptoms.IMU-838 is also currently in a pair of phase 3 trials in RMS, after previously hitting the primary endpoint of reducing brain lesions in a phase 2 trial. The phase 3 trials are analyzing the time to first symptom relapse as the primary endpoint.Immunic’s phase 3 RMS program recently underwent an interim futility analysis, the company said in October 2024, with the independent data monitoring committee determining that no changes to the trial protocol were needed.In addition to MS, Immunic is also testing IMU-838 in a phase 2 ulcerative colitis trial. The company has two other drug candidates in development, one clinical-stage asset for celiac disease and other gastrointestinal disorders and another preclinical gastrointestinal asset.This is, however, a more narrow focus for the biotech, which in 2023 revealed that it was deprioritizing development in psoriasis and castration-resistant prostate cancer and throwing its remaining resources to multiple sclerosis and celiac disease.

-01-引言1976年，美国科学家Poland与Glover在研究剧毒污染物二噁英（TCDD）时，意外发现了一种能与毒素特异性结合的蛋白——芳香烃受体（AHR）。自此近50年间，AHR因介导环境毒素的致癌、致畸作用而被视为"危险分子"，药物研发领域对其避之不及。 然而，近年研究揭示了AHR的另一面：它不仅参与免疫调控，更是连接肠道菌群代谢、膳食营养与疾病机制的核心枢纽。2016年，首个AHR激活剂Tapinarof获批治疗银屑病，标志着这一靶点从"毒理噩梦"正式逆袭为"免疫治疗新星"。-02-一、AHR的结构AHR是含bHLH-PAS结构域的配体依赖性转录因子。AHR在氨基末端包含一个bHLH结构域，这对DNA结合至关重要，其次是两个PAS结构域，PAS-a和PAS-B，以及羧基末端的一个转录激活结构域（TAD）。bHLH结构域介导AHR与特定DNA基序的结合，以控制靶基因的转录活性；它还促进了与ARNT的二聚化。PAS-A参与AHR-ARNT异二聚体的稳定。PAS-B含有一个配体结合口袋，激动剂通过诱导构象变化来结合和激活AHR，从而暴露核定位信号，促进AHR易位到核中。一旦与DNA结合，AHR的C末端TAD就会与转录调节因子和辅激活因子相互作用，激活靶基因的表达。PAS-A和PAS-B结构域之间的铰链区是灵活的，在配体诱导的构象变化中起着至关重要的作用。-03- 二、AHR的配体和信号通路AHR激动剂包括多种外源性和内源性分子。外源配体主要由二恶英等环境污染物组成，二恶英通常是工业过程和燃烧的产物。内源性配体包括几种代谢副产物和天然化合物，如色氨酸衍生物和微生物代谢物。在激动剂结合后，AHR信号机制可分为经典和非经典信号途径。重要的是，AHR信号模式的多样性使细胞能够对各种刺激做出反应，从而促进对细胞环境的适应。典型的AHR信号通路是由激动剂与细胞质中的AHR-伴侣复合物结合启动的。这种相互作用诱导AHR的构象变化，导致AIP从AHR复合物中解离，并暴露出N端核定位信号。AHR激动剂复合物随后与转运蛋白和输入蛋白-β相互作用，后者介导其核输入。一旦进入细胞核，AHR激动剂复合物就会与ARNT异二聚体化。这种异二聚是AHR转录活性的关键步骤，涉及AHR和ARNT的构象变化。AHR–ARNT复合物与特定的DNA序列结合，这些DNA序列包含一个共有的5′-TNGCGG-3′序列，其中AHR与5′-TGCG相互作用，ARNT与序列的GTG-3′半位点相互作用。在多种AHR靶基因中，有异生物质代谢酶，细胞因子IL-10和IL-21以及参与细胞代谢的酶。非典型AHR信号转导涉及核和/或细胞质途径。在核机制中，AHR激动剂复合物与其他转录因子相互作用并调节其活性。例如，AHR通过直接相互作用和间接机制控制核因子-κB（NF-κB）的活性。此外，AHR促进Krüppel样因子4（KLF4）和KLF6驱动的转录程序的表达，而抑制信号转导子和转录激活子（STAT）信号。-04-三、AHR信号的免疫调控作用AHR通过多层次的调控网络（代谢、转录、表观）平衡免疫激活与抑制，其在维持屏障稳态、调控适应性/固有免疫细胞分化及应答中具有重要作用。AHR在免疫系统中的免疫调节作用机制可归纳为以下方面：一、免疫稳态的维持AHR通过调控树突状细胞（DCs）功能，维持肠道上皮细胞的完整性。AHR激活的DCs通过诱导IL-10和IL-22的表达，促进调节性T细胞（Treg）分化，抑制促炎性T细胞（TH17），从而减轻结肠炎等炎症反应。此外，肠道共生菌代谢色氨酸（Trp）生成AHR配体（如吲哚类化合物），AHR激活后增强肠道抗菌肽表达，维持微生物群稳态。二、免疫细胞分化的调控树突状细胞（DCs）：AHR激活的DCs下调MHC II类分子和共刺激分子（CD80/CD86），减少促炎因子（IL-6、IL-12、TNF），并诱导吲哚胺2,3-双加氧酶（IDO1/IDO2）生成色氨酸代谢产物，促进Treg分化。 AHR激动剂（如TCDD）诱导DCs分泌TGF-β和IL-27，增强Tr1细胞生成，Tr1细胞是不表达转录因子Foxp3但产生高水平IL-10的调节性T细胞，从而抑制TH17细胞介导的自身免疫反应。T淋巴细胞：AHR信号通过配体特异性（如TCDD与FICZ）调控T细胞分化。例如： TGF-β联合TCDD诱导Foxp3+ Treg分化，抑制自身免疫；FICZ激活AHR驱动TH17分化，加重实验性自身脑脊髓炎（EAE）等疾病。此外，AHR通过色氨酸代谢生成犬尿氨酸（Kyn），抑制STAT1磷酸化，促进SMAD1介导的免疫抑制。先天性淋巴细胞（ILCs）：AHR对肠道ILC3的存活与功能至关重要，通过诱导IL-7R、Bcl-2和Notch表达，促进IL-22分泌，抵抗病原体（如Citrobacter rodentium）。AHR协同RORγt调控ILC3在感染中的抗菌反应。-05-四、靶向AHR的药物开发自身免疫疾病Tapinarof是一种天然鉴定的具有AHR激动剂活性的二苯乙烯化合物，由Dermavant Sciences开发，并于2022年获得FDA批准，用于治疗成人斑块状银屑病。临床前研究证实，tapinarof是一种直接与AHR-ARNT异二聚体结合的AHR激动剂。它诱导角质形成细胞中CYP1A1和皮肤屏障成分角蛋白、聚丝蛋白、外皮蛋白的表达，以及表皮屏障的神经酰胺脂质成分的表达，并抑制T细胞中促炎细胞因子的表达，包括IL-17A和IL-17F。在治疗成人斑块状银屑病的III期试验中，与赋形剂对照组相比，tapinarof局部用药显示出临床意义和统计学上的显著优势。此外，还观察到持续使用的持久效果和缓解效果。在一项长期扩展研究（PSOARING 3）中，41%接受tapinarof治疗的患者实现了疾病的完全清除，并且在停药后能够维持疾病控制，中位时间为4个月。tapinarof抑制了记忆T细胞在体外的产生、活性和持久性，这些效应可能有助于临床研究中观察到的缓解。DMVT-506是一种与tapinarof具有相似药理学特征的AHR激动剂，Dermavant Sciences正在开发用于其他炎症性疾病的药物。除了局部制剂外，DMVT-506还被开发为IBD的口服缓释剂型，以及哮喘和慢性阻塞性肺病等呼吸系统疾病的干粉吸入剂。Azora Therapeutics正在开发天然AHR激动剂靛玉红的局部和口服制剂，用于治疗过敏性皮炎，Galileo Biosystems正在开发治疗性AHR调节剂，用于治疗炎症和自身免疫性疾病。礼来公司最近为AHR激动剂颁发了两项专利，表明其对炎症领域的积极兴趣。癌症此外，AHR拮抗剂正在癌症患者中进行临床评估。BAY2416964是一种旨在抑制AHR的小分子，其目的是增强对癌症的免疫反应。一项I期临床试验正在确定BAY 2416964在晚期癌症患者中的最高耐受剂量（NCT04069026）。此外，BAY2416964与抗PD-1免疫检查点抑制剂pembrolizumab联合用药治疗晚期实体癌患者，如头颈部癌症、肺癌和癌症（NCT04999202）。同样，另一种名为IK-175（Ikena Oncology）的AHR拮抗剂正在早期试验中作为单一药物和与抗PD-1抗体nivolumab联合使用，用于晚期或转移性实体瘤患者，包括尿路上皮癌（NCT04200963）。其它除了以上的临床试验外，还有20项其他临床试验已经完成或正在进行中，以研究使用内源性和膳食配体以及合成小分子调节AHR的临床效果。在内源性配体中，补充l-色氨酸（一种代谢为AHR激动剂的氨基酸）正在评估对无麸质饮食无反应的活检确诊乳糜泻患者的疗效（NCT05576038）。另一项研究评估了内源性AHR激动剂（如Kyn）在识别与阻塞性睡眠呼吸暂停相关的高血压患者方面的鉴别潜力（NCT04646902）。菊粉是一种来自植物的膳食纤维，通过直接与AHR相互作用或增强AHR与XREs的结合来诱导CYP1A的表达。菊粉对慢性肾病患者肠道微生物组、肠道屏障功能、细菌代谢产物和免疫细胞的影响正在研究中（NCT05071131）。临床前和早期临床研究结果都支持这些化合物的治疗潜力，但在对其临床疗效得出明确结论之前，还需要进一步的临床研究。-06-结语AHR的逆袭史，验证了基础研究颠覆性突破的威力——通过解码生物学本质，曾经的"危险分子"也能蜕变为治疗利器。随着首个AHR药物落地，我们正站在免疫代谢治疗的新起点。未来，期待更多跨界创新将AHR的调控潜力转化为普惠疗法，为自身免疫病、肿瘤、感染性疾病患者带来新曙光。参考资料：1.The aryl hydrocarbon receptor: a rehabilitated target for therapeutic immune modulation. Nat Rev Drug Discov.2025 Apr 17.公众号内回复“ADC”或扫描下方图片中的二维码免费下载《抗体偶联药物：从基础到临床》的PDF格式电子书！公众号已建立“小药说药专业交流群”微信行业交流群以及读者交流群，扫描下方小编二维码加入，入行业群请主动告知姓名、工作单位和职务。