Novel Formulations for Injectable Growth Factors

描述（由申请人提供）：仅在美国，每年就有超过630万例骨折发生（Praemer et al. 1999），约15%的骨折表现为延迟或受损愈合。目前用于治疗迟发性骨折的临床应用需要开放性手术植入自体骨移植物。如果开放性手术与合并症混淆，或被认为是不可取的，微创注射治疗将为患者和医生提供另一种治疗选择。生长因子，特别是骨形态发生蛋白（BMPs）由于其强大的成骨活性，被用于脊柱融合和骨折愈合等一系列适应症（Mont等，2004年）。一种可注射的BMP载体将为这种强大的治疗分子家族的微创应用提供载体。（*1）在I期融资期间，我们探索了一种开发bmp注射给药系统的新方法，特别是fda批准的BMP-2。我们为这种潜在的产品制作了两种配方：一种是胶原基质，其中BMP-2结合肽共价附着在胶原基质上；另一种是胶原基质与双功能肽混合，由一个与胶原蛋白高亲和力的结合结构域和另一个与BMP-2高亲和力的结构域组成。第一种制剂符合我们的体外疗效标准，但未能形成稳定的水凝胶，导致其在体内骨诱导模型中失败。第二种配方，含有双功能BMP-2：胶原肽似乎满足我们的体外和体内性能标准。该技术在第一阶段开发，并在第二阶段提出商业化优化，代表了一种独特的生物材料，可能对许多医学适应症有用。我们的第二阶段提案有三个独立的目标：1)优化肽序列和合成以实现商业规模生产和配方；2)研究各改性水凝胶的生物相容性、毒性和稳定性；3)在兔截骨模型上测试可注射载体的体内成骨效果。开发一种新的递送基质，使用BMP-2的肽结合物，可能允许更大程度的控制生长因子释放。具体来说，一种可注射的BMP-2制剂可以通过微创手术治疗骨折。广泛应用的可注射生长因子可能会增强愈合的生物成分，促进更简单的手术干预，更快的愈合和改善的结果。通过将无创注射与靶向分子治疗相结合，我们希望增加生物制剂的局部保留，同时减少它们的剂量和伴随的费用。（*3）我们认为这个BMP-2递送平台可以作为其他生长因子的模型，如PDGF-BB、TGF-3或GDF7， affinenergy已经为这些生长因子开发了高亲和力结合肽。引导我们的BMP-2原型输送系统走向商业化是我们研究可注射生长因子广泛应用的第一步。公共卫生相关性：骨形态发生蛋白（BMPs）生长因子目前被用于促进骨生成和骨折愈合。仅在美国，每年就有超过630万例骨折发生，其中约15%的骨折表现为愈合延迟或受损。然而，目前使用的临床应用需要开放手术将载体/BMP组合插入愈合部位。通过微创手术输送bmp的能力将有相当大的临床效益。在本提案中，我们提出了一种新的方法来继续开发BMP-2的注射递送系统，以提高生长因子在修复部位的保留和有效性。将这项技术扩展到其他治疗性蛋白质，可以为其他医学适应症产生新的干预措施。

DESCRIPTION (provided by applicant): Over 6.3 million fractures occur each year in the United States alone (Praemer et al. 1999) and approximately 15% of fractures exhibit delayed or impaired healing. The clinical applications currently used to treat delayed fracture require open surgery to insert an autologous bone graft. If open surgery is confounded by co-morbidity or is deemed otherwise undesirable, a minimally invasive injectable therapy would provide patients and physicians with another treatment option. Growth factors, particularly bone morphogenetic proteins (BMPs) are employed for a range of indications including spinal fusion and fracture healing due to their potent osteogenic activity (Mont et al. 2004). An injectable BMP carrier would provide a carrier for the minimally invasive application of this powerful family of therapeutic molecules. (*1) During the Phase I funding period, we explored a novel approach toward developing an injectable delivery system for BMPs, specifically FDA-approved BMP-2. We generated two formulations for this potential product: a collagen matrix on which BMP-2 binding peptides were covalently attached and a second where a collagen matrix was mixed with a bifunctional peptide, comprised of a binding domain with high-affinity for collagen and another domain with high-affinity for BMP-2. The first formulation fulfilled our in vitro efficacy criteria, but failed to form a stable hydrogel leading to its failure in our in vivo osteoinduction model. The second formulation, containing bifunctional BMP-2: collagen peptides appeared to satisfy both our in vitro and in vivo performance criteria. The technology developed in Phase 1, and proposed here for commercial optimization in Phase 2, represents a unique biomaterial, potentially useful for a number of medical indications. Our Phase 2 proposal has 3 discrete aims: 1) optimize peptide sequence and synthesis for commercial scale production and formulation; 2) examine the biocompatibility, toxicity and stability of each modified hydrogel and 3) test the in vivo osteogenic efficacy of our injectable carriers in a rabbit osteotomy model. The development of a new delivery matrix, using peptide binders for BMP-2, may allow for a greater degree of controlled growth factor release. Specifically, an injectable BMP-2 formulation would allow for the treatment of fractures with a minimally invasive procedure. Broadly applied, injectable growth factors are likely to enhance the biological components of healing, encouraging simpler surgical intervention, faster healing and improved outcomes. By combining noninvasive injectability with a targeted, molecular therapy we hope to increase localized retention of biologics while decreasing their dosages, and concomitant expense. (*3) We feel this platform for BMP-2 delivery could be used as a model for other growth factors, such as PDGF-BB, TGF-3 or GDF7, for which Affinergy has already developed high-affinity binding peptides. Guiding our prototype BMP-2 delivery system toward commercialization represents our first step toward investigating the broad applications of injectable growth factors. PUBLIC HEALTH RELEVANCE: Growth factors called Bone Morphogenetic Proteins (BMPs) are currently used to promote osteogenesis and fracture healing. Over 6.3 million fractures occur each year in the United States alone and approximately 15% of fractures exhibit delayed or impaired healing. The clinical applications currently in use, however, require open surgery to insert the carrier/BMP combination at the site of healing. There would be considerable clinical benefit from the ability to deliver BMPs via a minimally invasive procedure. In this proposal, we present a novel approach to continue the development of an injectable delivery system for BMP-2 that improves the retention and effectiveness of a growth factor at the site of repair. Expanding this technology to other therapeutic proteins could generate novel interventions for additional medical indications.