Eflornithine Hydrochloride

Abstract Bone metastasis is a lethal consequence of breast cancer. AT-rich interaction domain 1 A gene (ARID1A), a subunit of the switch/sucrose non-fermentable (SWI/SNF) complex, regulates immunosuppressive tumor microenvironment. However, its specific role in bone metastasis remains unclear. Here, we show that female patients with ARID1A‑mutated triple negative breast cancer (TNBC) exhibit a higher bone metastasis incidence. Most ARID1A mutations result in loss of protein expression. ARID1A deficiency upregulates the arginine metabolic pathway, increasing ornithine and spermine levels that promote the expansion of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) within the bone marrow, thereby facilitating bone metastasis. Targeting key enzymes of arginase 2 (ARG2) and ornithine decarboxylase 1 (ODC1) in arginine metabolic pathway effectively reduces bone metastasis in ARID1A-deficient models. Collectively, these findings reveal that ARID1A deficiency promotes bone metastasis by activating arginine metabolism to expand PMN-MDSCs and potentially offers therapeutic strategies for preventing bone metastasis in female patients with ARID1A-deficient TNBC.一、核心研究团队与领域 本文的通讯作者来自 复旦大学附属上海肿瘤医院 的核心团队： 胡夕春教授：复旦大学附属肿瘤医院大内科首席专家，担任ESMO乳腺癌Faculty Member及ABC5 panelist，同时是中国抗癌协会多原发和不明原发肿瘤专委会主委。长期专注于乳腺癌的精准治疗、化疗及新药临床试验，在CDK4/6抑制剂耐药及内分泌治疗等领域有深厚造诣。 陶中华副主任医师：复旦大学肿瘤学专业毕业，国家科技重大专项新药研发骨干，擅长复发转移性乳腺癌的个体化治疗与临床研究。 杨梦迪博士：主要从事乳腺癌骨转移的基础研究与转化医学，在骨转移标本的脱钙处理和免疫组化检测方面积累了丰富的技术经验。 三位通讯作者形成了“基础机制研究→临床验证→转化治疗”的完整闭环，这也是本文能够打通从分子机制到动物模型再到临床队列全链条的关键所在。二、研究背景：TNBC骨转移的“隐秘战场” 三阴性乳腺癌是乳腺癌家族中最凶险的亚型，骨转移的发生率极高。当肿瘤细胞播散至骨骼后，骨骼微环境非但不是“死亡陷阱”，反而成为一个支持肿瘤细胞存活和休眠的天然庇护所。更棘手的是，骨转移灶还会成为“二级转移枢纽”，后续进一步播散至肺、肝、脑等重要脏器。然而，长期以来TNBC骨转移的分子机制始终未被完全阐明，临床上缺乏有效的防治手段。 ARID1A是染色质重塑复合体SWI/SNF的核心亚基，在约7%的乳腺癌中存在失活突变，导致ARID1A蛋白表达缺失。以往研究主要关注ARID1A在上皮-间质转化和抗肿瘤免疫中的作用，但其与骨转移的关联一直处于空白状态。与此同时，精氨酸代谢作为肿瘤微环境中连接癌细胞与免疫细胞的关键代谢通路，其是否参与了ARID1A缺陷介导的骨转移，同样是一个悬而未决的科学问题。 补充进展：2026年初的多项研究揭示，ARID1A不仅依赖SWI/SNF复合体发挥抑癌功能，还可能存在不依赖SWI/SNF的独立机制调控肿瘤进展，这为本研究发现的ARID1A缺陷激活精氨酸代谢的全新机制提供了重要的背景支撑。此外，多胺代谢失调与肿瘤免疫抑制的关系也日益受到关注，针对ODC1的抑制剂DFMO联合多胺转运抑制剂的临床试验正在晚期实体瘤中积极推进。三、现象发现：从663例患者ctDNA中锁定的线索 这项研究有一个扎实的临床起点——研究者对663例转移性乳腺癌患者的外周血进行了循环肿瘤DNA分析。通过高通量基因测序，他们系统排查了多个基因突变与器官特异性转移的关联。结果发现：ARID1A突变在所有被检测的基因中与骨转移的关联最为显著。值得注意的是，约68%的ARID1A突变为截短或缺失事件，这些突变类型被预测会导致ARID1A蛋白完全失活，因此研究者推测ARID1A蛋白功能缺失才是驱动骨转移的核心因素。 进一步分层分析显示，这一关联仅存在于三阴性乳腺癌亚型中，而在Luminal A、Luminal B或HER2阳性乳腺癌中均不显著。为了从蛋白层面验证这一现象，研究团队又利用108例TNBC患者的组织微阵列进行了免疫组化分析，结果再次证实：低ARID1A表达组的骨转移发生率高达49.1%，而高表达组仅为23.5%。这一从基因到蛋白的双重证据，为后续机制研究奠定了坚实的临床基础。 补充进展：精氨酸代谢在骨转移中的作用已逐渐成为研究热点。2026年初的一项研究发现，lncRNA SNHG18表达下调通过上调ARG2和NOS2导致精氨酸耗竭，同样促进前列腺癌骨转移的免疫抑制微环境形成，表明精氨酸代谢可能是多种肿瘤骨转移的共同机制之一。此外，MDSCs在骨转移中的核心作用也被系统性梳理——骨转移将骨髓转化为“MDSC扩增器”，血管、基质和代谢线索共同促进MDSCs的募集和功能成熟。四、关键蛋白/基因的研究进展 ARID1A：作为SWI/SNF复合体的核心组分之一，它的失活会导致染色质可及性紊乱。已有研究揭示其在免疫调节中的作用，但ARID1A与精氨酸代谢通路之间的交叉对话此前从未被报道，这使得本文在代谢重编程领域具备了高度的原创性。 ARG2：将精氨酸转化为鸟氨酸的关键限速酶。本研究发现ARID1A缺陷时，转录因子ARID3A被招募至ARG2增强子区域，激活其转录。 ODC1：将鸟氨酸转化为多胺的限速酶，是多胺代谢通路中的核心调控节点。DFMO正是其特异性抑制剂，在本研究中被用于靶向干预。 PMN-MDSCs：在人类中鉴定为CD11b⁺CD14⁻HLA-DR⁻/ˡᵒʷCD66b⁺，在形态上与中性粒细胞相似，是肿瘤微环境中最主要的MDSCs亚群，通过分泌多种免疫抑制因子构建免疫屏障。本研究首次揭示了ARID1A缺陷通过代谢产物驱动其扩增的全新机制。五、研究思路：一条完整的级联通路 本文的研究逻辑清晰且层层递进： 临床发现阶段：ctDNA队列筛查→ARID1A突变与TNBC骨转移强关联→蛋白水平验证→明确现象存在。 体内功能验证阶段：构建ARID1A敲除和过表达细胞系→心内注射和胫骨内注射两种骨转移动物模型→BLI动态监测→确认ARID1A缺陷促进骨转移。 机制探索阶段：代谢组学+转录组学双组学分析→精氨酸代谢通路富集→ATAC-seq+ChIP-seq揭示表观调控→ARG2和ODC1上调→鸟氨酸和精胺积累。 免疫机制解析阶段：scRNA-seq分析骨髓免疫细胞→PMN-MDSCs比例升高→拟时序追踪发育轨迹→共培养验证代谢产物驱动PMN-MDSCs扩增。 靶向治疗验证阶段：CB-1158+DFMO双靶点抑制→体内外功能评估→安全性评估。六、详细研究方法 临床队列分析：收集663例转移性乳腺癌患者的ctDNA检测数据，结合临床随访信息，分析基因突变与器官特异性转移的相关性。同时构建108例TNBC组织微阵列进行ARID1A蛋白表达的IHC评分。 动物模型：采用心内注射（左心室注射2×10⁵个肿瘤细胞）和胫骨内注射两种经典骨转移动物模型，配合活体生物发光成像对肿瘤进展进行纵向监测。同时构建Arid1aᶠˡᵒˣ/ᶠˡᵒˣ；Mmtv-Cre⁺条件性敲除小鼠，在乳腺组织中特异性敲除Arid1a。 多组学分析：非靶向代谢组学（LC-MS/MS）和转录组学联合分析差异通路；ATAC-seq检测全局染色质可及性变化；H3K27ac ChIP-seq识别增强子活性区域；后续通过ChIP-qPCR和双荧光素酶报告基因实验验证ARID3A与ARG2增强子的结合。 单细胞转录组测序：对骨髓样本进行10× Genomics平台scRNA-seq，结合t-SNE降维和Monocle拟时序分析，追踪PMN-MDSCs的发育轨迹。 体外共培养体系：将小鼠骨髓来源细胞或人外周血PBMC与肿瘤细胞共培养72小时，在GM-CSF和IL-6诱导下生成MDSCs，通过流式细胞术进行表型鉴定。 靶向干预实验：使用CB-1158（ARG2抑制剂，100mg/kg，每日两次灌胃）和DFMO（ODC1抑制剂，100mg/kg，每日一次灌胃），评估单药及联合用药对骨转移和PMN-MDSCs的影响，同时开展全面的肝肾功能和血常规安全性评估。七、结果部分的详细解析7.1 ARID1A缺陷通过精氨酸代谢促进骨转移 代谢组学和转录组学联合分析结果显示，精氨酸和脯氨酸代谢通路在ARID1A敲除细胞中富集最为显著。转录组热图进一步定位出差异最明显的基因：ODC1在敲除细胞中上调最为突出，ARG2也显著升高，而OAT无明显变化。ATAC-seq显示ARID1A敲除后全局染色质可及性下降，但在ARG2的特定调控区域，H3K27ac的富集增加了10倍。通过基序富集分析鉴定出候选转录因子ARID3A，ChIP-qPCR和双荧光素酶报告实验证实ARID3A直接结合ARG2增强子并驱动其转录激活。7.2 肿瘤细胞分泌鸟氨酸和精胺驱动PMN-MDSCs扩增 LC-MS/MS定量分析显示，敲除细胞内鸟氨酸和精胺水平显著升高，而精氨酸水平下降。令人意外的是，外源性补充鸟氨酸和精胺对肿瘤细胞自身的增殖和迁移无直接影响，提示这些代谢产物主要作用于微环境。通过scRNA-seq分析骨髓免疫细胞组分，发现敲除组中PMN-MDSCs的比例从37.11%显著升高至40.03%。拟时序分析表明PMN-MDSCs主要由中性粒细胞转化而来，且来自敲除组的细胞在最具免疫抑制功能的“State 3”中占绝大多数。体外共培养证实鸟氨酸和精胺直接诱导PMN-MDSCs扩增并上调PMN-MDSCs中ARG2和SAT1的表达。7.3 靶向精氨酸代谢有效抑制骨转移 CB-1158和DFMO对TNBC细胞均无直接细胞毒性，但能显著降低共培养体系中PMN-MDSCs的比例。在体内模型中，单药治疗显著减少骨转移发生率和肿瘤负荷，联合用药效果最佳且呈叠加效应而非协同效应。安全性评估显示两组药物对肝肾功能、血常规均无显著影响，组织病理学检查未见器官损伤。临床预后分析表明，低ARID1A表达且同时高表达ARG2和ODC1的TNBC患者预后最差，进一步确认了该通路的临床相关性。八、研究创新性 首次揭示ARID1A缺陷与精氨酸代谢之间的交叉对话：在此之前，ARID1A的代谢调控研究主要集中在糖酵解和脂质代谢，本文首次将ARID1A与精氨酸代谢通路关联，拓展了染色质重塑因子在代谢调控中作用的认识。 构建了一条完整的“染色质重塑→代谢重编程→免疫重塑→转移促进”级联通路：从ARID1A缺陷到染色质可及性改变，再到ARG2转录激活和代谢产物累积，最终到PMN-MDSCs扩增和骨转移，机制链条完整且逻辑严密。 明确揭示了代谢产物在骨转移中的“非细胞自主性”作用机制：鸟氨酸和精胺在骨转移中主要作用于微环境而非肿瘤细胞自身，这一发现颠覆了传统上从癌细胞“自我增益”角度理解代谢调控的思维定势。 提供了具有明确临床转化潜力的治疗策略：CB-1158已在晚期实体瘤的I/II期临床试验中展现出可接受的安全性和初步的免疫调节活性（NCT02903914；NCT03314935）；DFMO正在肿瘤学领域被积极“老药新用”（NCT06059118；NCT06892678；NCT03536728）。本文的发现为精准锁定获益人群提供了分子标志物。 多组学技术与多种动物模型的系统整合：从ctDNA临床队列到代谢组学、转录组学、单细胞转录组学到表观组学，再以心内注射、胫骨内注射和条件性敲除自发性肿瘤模型三重验证，形成了多维度、多层次的完整证据链。 补充进展：2025年，胡海团队的研究表明，临床乳腺癌患者血清精氨酸水平与肿瘤进展呈显著正相关，且该促癌效应严格依赖于完整免疫系统的存在。这一发现与本研究成果互为印证，进一步强化了精氨酸代谢→免疫微环境→肿瘤进展这一轴心的科学价值。此外，2025年的一项研究也揭示，癌症细胞可通过“精氨酸→巨噬细胞→T细胞”的代谢互作链路驱动免疫逃逸，提示精氨酸代谢是肿瘤微环境中癌细胞与免疫细胞对话的关键桥梁。九、全文总结与未来研究展望9.1 全文总结 本研究系统揭示了一条全新的TNBC骨转移驱动路径：ARID1A缺陷导致染色质重塑异常，转录因子ARID3A被招募至ARG2增强子区域激活其转录，从而上调精氨酸代谢通路，促使鸟氨酸和精胺在肿瘤细胞中大量积累并释放入骨微环境。这些代谢产物进一步驱动骨髓中PMN-MDSCs的扩增，构建免疫抑制微环境，最终促进TNBC骨转移。靶向ARG2（CB-1158）和ODC1（DFMO）能够有效抑制这一过程，为ARID1A缺陷型TNBC骨转移的精准治疗提供了坚实的新策略。9.2 未来研究潜力与启示 联合靶向精氨酸代谢与免疫检查点抑制剂：PMN-MDSCs是免疫抑制的核心源头，靶向精氨酸代谢以清除PMN-MDSCs后，可能为PD-1/PD-L1抑制剂创造更有利的治疗窗口。 鸟氨酸和精胺作为液体活检标志物：本研究发现患者血清中这两种代谢物水平与骨转移发生率显著相关，未来可探索其在骨转移早期预警中的临床价值。 ARID1A突变检测进入骨转移风险评估体系：ARID1A突变在TNBC中约占7.1%，对这部分患者进行早期骨转移风险评估和预防性干预，有望实现真正的“分型精准治疗”。 探索ARID1A缺陷在其他癌种骨转移中的作用：ARID1A突变在子宫内膜癌、卵巢癌、肝癌等肿瘤中同样普遍存在。已有文献报道精氨酸代谢在前列腺癌骨转移中也参与构建免疫抑制微环境，提示本研究揭示的机制可能具有跨癌种的普适性。 CB-1158和DFMO的联合方案优化：本研究已证明两药联合在减少PMN-MDSCs方面呈现叠加效应，未来可进一步开展剂量优化研究，探索更低有效剂量下的药效学变化。 参考文献： Targeting arginine metabolism reverses bone immunosuppressive microenvironment and metastasis in ARID1A-deficient triple negative breast cancer

A decades-old drug once used to treat sleeping sickness is now showing surprising promise against an ultra-rare and life-threatening genetic disorder called Bachmann-Bupp syndrome (BABS). Early patient treatments suggest the drug, DFMO, may ease severe symptoms by targeting the underlying genetic malfunction. Researchers have already treated a handful of patients with encouraging results, but progress has been slowed by regulatory and logistical hurdles.A medication that has been around for decades and used to treat several conditions, including a chronic parasitic infection, is now emerging as a potential option for patients with a different and far rarer disease. Early findings suggest the drug could help people with Bachmann-Bupp syndrome (BABS), a life-threatening genetic disorder that affects only a small number of individuals worldwide. This progress is being driven by a new collaboration between Corewell Health, Michigan State University, and Every Cure, a nonprofit biotech group focused on finding new uses for existing drugs. "Beyond helping us build preclinical studies and retrospective analyses, the team at Every Cure has already begun helping us navigate regulatory pathways and compliance on so many levels in the hopes that we can treat more of our BABS patients," said Caleb Bupp, M.D., pediatric geneticist for Corewell Health Helen DeVos Children's Hospital in Grand Rapids, Michigan. "They are opening doors that we never would have been able to crack open. It's a hopeful and exciting time for all of us and more importantly, our patients." What Is DFMO and How It Works The drug, called difluoromethylornithine, also known as DFMO or eflornithine, has a long history in medicine. It has been used to treat West African sleeping sickness, a chronic illness spread by the tsetse fly. It is also used to reduce unwanted facial hair in women and to help prevent neuroblastoma from returning. Researchers at Corewell Health and Michigan State University College of Human Medicine have now identified another possible use. They found that DFMO may help treat Bachmann-Bupp syndrome and have already administered it to a small number of patients through an FDA-approved, single-patient investigational protocol. Understanding Bachmann-Bupp Syndrome (BABS) BABS is caused by gain-of-function mutations in the ornithine decarboxylase, or ODC1 gene. These mutations lead to serious developmental challenges, including significant delays, low muscle tone, and hair loss. DFMO directly targets this pathway. It works by inhibiting the ODC protein, which in turn reduces the excessive enzyme activity caused by the mutated gene. In the limited number of patients treated so far, this approach has led to improvements in several symptoms. "I've studied DFMO and its effect on the ODC1 gene for three decades, including its clinical use in pediatric neuroblastoma," said MSU pediatrics professor André Bachmann, Ph.D., who along with Dr. Bupp collaborated to be the first to identify BABS in a patient. "It was a chance encounter with Dr. Bupp that we connected and were able to use DFMO on a patient -- and now five others -- with promising early results." Challenges Slowing Progress Despite the encouraging early outcomes, moving this potential treatment forward has not been easy. The condition itself is extremely rare, with only about 20 reported cases worldwide, making it difficult to build awareness and design large studies. Regulatory requirements and the complexity of launching clinical trials have also delayed progress. Although the Food and Drug Administration (FDA) has encouraged Drs. Bupp and Bachmann to proceed with a formal trial, key hurdles remain, including defining study goals and reaching enough patients. "For the past year, we've been at a standstill as far as moving our DFMO therapy forward," Dr. Bupp said. New Partnership Aims to Accelerate Research Every Cure is stepping in to help address these obstacles. The organization is working to strengthen the scientific evidence, increase awareness among doctors and rare disease groups, and support systems that ensure patients are properly identified and treated as research continues. "Our role is to help bridge this gap by strengthening the evidence behind BABS and DFMO through preclinical studies, increasing awareness among physicians and rare disease organizations, and ensuring that no child goes undiagnosed or untreated," said David Fajgenbaum, M.D., co-founder and Every Cure president. The three groups have already begun building on years of prior research led by Drs. Bachmann and Bupp, along with Corewell Health physician Surender Rajasekaran, M.D., and other collaborators. A preclinical study is expected to begin next year, marking an important step toward potentially bringing this therapy to more patients.