The Efficacy of combination therapy in Osteogenesis Imperfecta

 描述(由申请人提供)：我们假设增强促合成代谢的LRP5信号将是治疗成骨不全(OI)患者的有效策略，OI是一种影响近28,000名美国公民的遗传性疾病。我们使用了4种不同的OI小鼠模型来验证我们的假设，方法是将这些小鼠培育成具有高骨量的品系，导致Lrp5A214V等位基因，并给予Sost抑制抗体(scl-Ab)。我们发现，通过Lrp5A214V等位基因或通过scl-Ab从药理上增强LRP5信号，在每种OI模型中都能改善骨性能。我们现在想要确定抗SOST治疗的骨量和强度的增加是否随着治疗时间的延长而继续增加，在OI小鼠中抗SOST治疗是否优于抗吸收治疗，以及是否将通过将合成代谢反应与抗吸收治疗“巩固”来维持由scl-Ab引起的增加。我们将比较Scl-Ab和Alendronate，并将接受Vehicle或Scl-Ab治疗的12周龄OI小鼠随机分为下一次接受Vehicle或Alendronate治疗的12周小鼠。我们将使用多种方法评估骨性能，包括多荧光标记和定量组织形态计量学、骨折的高分辨率X射线、骨密度和总骨量的DEXA、微观结构的微CT以及骨强度的全股骨三点弯曲和椎体压缩。我们还想测试增强LRP5信号和抑制转化生长因子B信号的“联合”疗法是否比单独使用任何一种疗法都要好。几位研究人员的研究表明，转化生长因子过度活跃对骨骼有害，是OI的常见现象。此外，尽管我们发现增强LRP5信号显著改善了中到重度OI小鼠的骨特性，但它并没有使它们的骨特性与接受相同治疗的野生型小鼠的骨特性相同。因此，我们在处理中、重度OI的方法上有进一步改进的空间。我们将使用Lrp5A214V等位基因增强野生型小鼠和OI小鼠的LRP5信号，然后随机选择接受转化生长因子抑制抗体1D11的动物。我们将比较野生型和OI小鼠的骨骼特性，在有和没有增强LRP5信号的情况下，以及在有和没有抑制转化生长因子的情况下。我们希望这些原则性实验的证明将表明，LRP5信号的药理增强引起的骨性能的改善比抗吸收疗法更好，不会随着时间的推移而停滞，如果需要，可以用抗吸收疗法来“巩固”。我们还将确定以骨骼中两条重要信号通路为靶点的“联合”疗法是否优于单独靶向其中一条途径。这些实验将建立一个科学基础，为哪些OI患者最有可能从新疗法中受益以及哪些治疗方案将提供最佳结果提供指导。

 DESCRIPTION (provided by applicant): We hypothesized that enhancing LRP5 signaling, which is pro-anabolic, would be an effective treatment strategy for patients with Osteogenesis Imperfecta (OI), a genetic disorder that affects nearly 28,000 US citizens. We tested our hypothesis using 4 different mouse models of OI by breeding these mice to a strain that has the high bone mass causing Lrp5A214V allele and by giving a SOST inhibitory antibody (Scl-Ab). We found that enhancing LRP5 signaling, genetically via the Lrp5A214V allele or pharmacologically via Scl-Ab, improved bone properties in each OI model. We now want to determine whether the gains in bone mass and strength from anti-SOST therapy continue to increase as the duration of therapy is lengthened, whether anti-SOST therapy is superior to anti-resorptive therapy in OI mice, and whether increases caused by Scl-Ab will be maintained by "consolidating" the anabolic response with an anti-resorptive therapy. We will compare Scl-Ab versus Alendronate, and also randomize 12-week-old OI mice that had received vehicle or Scl-Ab to next receive vehicle or Alendronate an additional 12 weeks. We will evaluate bone properties using a variety of measures including multi-fluorochrome labeling and quantitative histomorphometry, high resolution X-ray for fracture, DEXA for bone mineral density and total bone mass, µCT for microstructure, and whole femur 3-point bending and vertebral compression for bone strength. We also want to test whether a "combination" therapy that couples enhancing LRP5 signaling and inhibiting TGFß signaling is better than either therapy alone. Studies from several investigators suggest that TGFß over-activity is deleterious to bone and is a common occurrence in OI. Also, although we found that enhancing LRP5 signaling significantly improved bone properties in mice with moderate to severe OI, it did not bring their bone properties to those of their wild-type littermates that received the same therapy. Therefore, there is room for further improvement in the way we will treat moderate and severe OI. We will enhance LRP5 signaling in wild-type mice and mice with OI using the Lrp5A214V allele and then randomize the animals to receive the TGFß inhibitory antibody 1D11. We will compare bone properties in the wild-type and OI mice, with and without enhanced LRP5 signaling, and with and without TGFß inhibition. We hope these proof of principle experiments will show that the improvement in bone properties caused by pharmacologic enhancement of LRP5 signaling is better than by anti-resorptive therapy, does not plateau over time and, if needed, can be "consolidated" with an anti-resorptive therapy. We also will determine whether a "combination" therapy that targets two important signaling pathways in bone is superior to targeting either pathway alone. These experiments will create a scientific foundation that will provide guidance regarding which OI patients are most likely to benefit from new therapies and what therapeutic regimens will provide the best outcome.