Preclinical drug development in pancreatic cancer

我的实验室旨在通过开发新的抗癌药物来满足胰腺癌患者对更有效治疗的未得到满足的医疗需求。过去一年在药物开发项目方面取得的科学成果包括：1.Metarrestin的临床翻译。Metarrestin是一种新型的、一流的小分子抑制剂，对癌细胞的转移表型具有选择性活性。它在胰腺癌和其他癌症转移模型中具有令人印象深刻的活性。在NCATS的弥合介入开发差距(Bridgs)计划的支持下，IND使临床级别的Metarrestin胶囊的研究和制造完成。食品和药物管理局于2019年11月批准了IND申请(IND编号146042)。采用人类首个安全的起始剂量水平，每48小时口服1毫克，I期临床方案NCI 20-C-0023；NCT04222413目前正在招募晚期实体器官癌症患者，以确定该药物的安全性和耐受性。来自第一批接受Metarrestin治疗的患者的初步PK数据似乎表明，在多次给药后，Metarrestin在血浆中达到治疗水平。预计目前的给药时间表将修改为每周两次或每周一次，以减少Metarrestin的药物积累并优化暴露。临床前工作已确定在实体器官癌中上调的翻译延长因子eEF1A2是Metarrestin的分子靶点。因子eEF1A2稳定核仁PeBoW复合体，以前没有被确定为癌症靶点，它由BOP1、PES1和WDR12组成。抑制eEF1A2会导致PeBoW复合体快速解体，PeBoW组分移位到核内，失去大的47S核糖体RNA前体的剪接，失去rRNA处理功能，失去核糖体预组装，核糖体生物发生停滞，以及细胞蛋白质合成功能的丧失。Metarrestin通过丝氨酸331和化合物的环己醇基之间的氢键与eEF1A2结合，并通过翻译后修饰引导Metarrestin与eEF1A2的结合，这在转移癌细胞和正常细胞中有所不同。已经产生了用丝氨酸取代eEF1A2第331位丙氨酸并显示出Metarrestin神经毒性的基因组编辑小鼠，这些小鼠被用来(1)研究Metarrestin在体内与其分子靶点的结合；(2)建立可预测神经表型的信息PK信号，如癫痫和癫痫脑病，以提高药物警戒性和Metarrestin抗癌治疗的安全性。药物化学工作已经开始，以开发一种后备候选药物，其穿越血脑屏障的能力降低，并降低神经副作用的风险。另外，体外研究已经确定了eEF1A2的独特结合伙伴以及与Metarrestin活性相关的eEF1A2的翻译后修饰，这将被作为未来可能的生物标记物或基础设计组合研究的线索。2.针对TAMs上CD206的小分子先天检查点调节剂的临床前研究。一流的合成宿主防御肽RP-182针对M2样TAM上的甘露糖受体CD206，我们的团队证明它是一种有吸引力的免疫治疗药物，用于目前对T细胞激活没有免疫检查点抑制作用的免疫“冷”癌。在与CD206受体对接的RP-182衍生的药效团模型的大型化学库的电子筛选中，已经确定了基于苯基咪唑[2，3]吡嗪的候选药物NCGC00413972。NCGC00413972在大量的激酶、GPCRs或离子通道中的靶外活性有限，在大鼠毒性研究中显示出较大的治疗窗口，并计划在申请支持IND使能研究和生产临床级化合物之前，在携带肉瘤的狗身上进行安全性、耐受性和有效性测试。最近的研究表明，NCGC00413972具有双重功能，通过激活典型的核因子-kB信号和早期的炎症基因反应，诱导M2巨噬细胞杀伤。内化的NCGC00413972诱导I型干扰素反应，将M2重新编程为M1样巨噬细胞，诱导癌细胞吞噬和抗肿瘤活性。额外的作用机制研究将为原理设计的组合提供信息，以增强NCGC00413972的活性。3.胰腺癌转基因动物的临床前研究表明，抑制转化生长因子β和吉西他滨可以抑制肿瘤生长，延长小鼠的生存时间。转化生长因子β抑制介导的基质调节通过改变癌症相关成纤维细胞(CAF)表型(增加炎症与骨髓成纤维细胞CAF的比率)来增加这些肿瘤的血流灌注，由于骨髓成纤维细胞CAF组分的内在耐药机制，这些肿瘤迅速恢复到治疗前的值。转化生长因子β抑制与吉西他滨联合的抗肿瘤活性是通过两种药物的免疫原性协同作用产生的，包括将T调节细胞从效应记忆重新编程为幼稚细胞表型。额外的临床前研究发现，免疫检查点PD-L1的上调是该方法的耐药机制之一。临床方案“免疫检查点抑制剂M7824和免疫细胞因子M9241联合立体定向全身放射治疗(SBRT)治疗成人晚期胰腺癌”(NCI 20-C-0074；NCT04327986)正在测试通过添加促免疫原剂包括IL-12激动剂、PD-L1检查点抑制剂和立体定向放射治疗来克服对TGFβ抑制的耐药性的概念。

My laboratory aims to address the unmet medical need for more effective treatments for pancreas cancer patients by developing new cancer drugs. Scientific achievements with regard to the pursued drug development projects in the last year include: 1. Clinical translation of metarrestin. Metarrestin is a novel, first-in-class small molecule inhibitor with selective activity against the metastatic phenotype of cancer cells. It has impressive activity in pancreatic and other cancer metastasis models. Supported by NCATS' Bridging Interventional Development Gaps (BrIDGs) program IND enabling studies and manufacturing of clinical grade metarrestin capsules were completed. FDA approved the IND application in November 2019 (IND#146042). Using a safe first-in-human starting dose level of 1mg every 48 hours administered orally the phase I clinical protocol NCI 20-C-0023; NCT04222413 is currently accruing patients with advanced solid organ cancers to determine safety and tolerability of the drug. Preliminary PK data from the first patients treated with metarrestin appear to indicate that after multiple dosing metarrestin reaches therapeutic levels in plasma. It is expected that the current dosing schedule will be modified to twice a week or once weekly dosing to reduce drug accumulation of metarrestin and optimize exposure. Preclinical work has identified the translation elongation factor eEF1A2 upregulated in solid organ cancers as the molecular target of metarrestin. The factor eEF1A2 stabilizes the nucleolar PeBoW complex, previously not identified as a cancer target, which is comprised of the components BOP1, PES1, and WDR12. Inhibition of eEF1A2 leads to rapid disassembly of the PeBoW complex, translocation of the PeBoW components into the nucleus, loss of splicing of the large 47S ribosomal RNA precursors, loss of rRNA processing function, loss of ribosomal pre-assembly, stalling of ribosomal biogenesis, and loss of protein synthesis function of the cell. Metarrestin binds to eEF1A2 via formation of hydrogen bonds between serine 331 and the cyclo-hexanol group of the compound and binding of metarrestin to eEF1A2 is guided by post-translational modification which differ in metastatic cancer cells vs normal cells. Genome-edited mice which have replaced the murine alanine on position 331 of eEF1A2 with serine and which phenocopy the neurotoxicity of metarrestin have been generated and are used to (1) study the binding of metarrestin to its molecular target in vivo and (2) establish informative PK signatures which are predictive of the neurological phenotype, such as seizures and epileptic encephalopathies to improve pharmacovigilance and the safety profile of anticancer therapy with metarrestin. Medicinal chemistry work has been started to develop a back-up candidate with decrease ability to cross the blood brain barrier and lower the risk of neurological side effects. Additional in vitro studies have identified unique binding partners of eEF1A2 as well as post-translational modifications of eEF1A2 associated with metarrestin activity which will be interrogated as possible future biomarkers or leads for rationale-designed combination studies. 2. Preclinical development of small molecule-based innate checkpoint modulators targeting CD206 on TAMs. The first-in-class synthetic host defense peptide RP-182 targets the mannose receptor CD206 on M2-like TAMs and was shown by our group to be an attractive agent for immunotherapy in immunologically 'cold' cancers which currently don't respond to T cell activation via immune checkpoint inhibition. In silico screening of large chemical libraries with a pharmacophore model derived from RP-182 docked onto the CD206 receptor has identified the phenyl-imidazo[2,3] pyrazine-based drug candidate NCGC00413972. NCGC00413972 has limited off-target activity in large panels of kinases, GPCRs, or ion channels, showed a large therapeutic window in rat toxicity studies, and is planned to undergo safety, tolerability, and efficacy testing in sarcoma-bearing dogs prior to applying for support of IND enabling studies and production of clinical grade compound. Recent work showed that NCGC00413972 has dual function; via activation of canonical NF-kB signaling and an early inflammatory gene response the candidate induces M2 macrophage killing. Internalized NCGC00413972 induces an interferon type I response which reprograms M2 to M1-like macrophages, induces cancer cell phagocytosis, and anti-tumor activity. Additional mechanism of action studies will inform rationale-designed combinations to enhance the activity of NCGC00413972. 3. Preclinical work in transgenic animals with pancreas cancer has shown that TGFbeta inhibition and gemcitabine cooperate to suppress tumor growth and extend survival in mice. TGFbeta inhibition-mediated stromal modulation increases perfusion via alteration of the cancer-associated fibroblast (CAF) phenotype (increases the ratio of inflammatory vs myelofibroblastic CAFs) in these tumors which rapidly returned to pre-treatment values due to intrinsic resistance mechanisms in the myelofibroblastic CAF fraction. Anti-tumor activity of TGFbeta inhibition in combination with gemcitabine is generated via immunogenic cooperativity of the two agents including the reprogramming of T regulatory cells from an effector-memory towards a naive cell phenotype. Additional preclinical work identified upregulation of the immune checkpoint PD-L1 as one of the resistance mechanisms of this approach. The clinical protocol 'Immune Checkpoint Inhibitor M7824 and the Immunocytokine M9241 in Combination With Stereotactic Body Radiation Therapy (SBRT) in Adults With Advanced Pancreas Cancer' (NCI 20-C-0074; NCT04327986) is testing the concept of overcoming resistance to TGFbeta inhibition via the addition of pro-immunogenic agents including IL-12 agonists, PD-L1 checkpoint inhibitors, and stereotactic radiation therapy.