Novel Formulations for Injectable Growth Factors

描述（由申请人提供）：仅在美国，每年就发生超过630万例骨折（Praemer等人，1999），约15%的骨折愈合延迟或受损。目前用于治疗迟发性骨折的临床应用需要开放手术来插入自体骨移植物。如果开放手术被合并症混淆或被认为是不可取的，微创注射疗法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（BMP），由于其强效成骨活性，可用于一系列适应症，包括脊柱融合和骨折愈合（Mont等人，2004）。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）在第一阶段资助期间，我们探索了一种新的方法来开发BMP的注射输送系统，特别是FDA批准的BMP-2。我们为这种潜在的产品产生了两种制剂：一种胶原基质，其上共价连接有BMP-2结合肽，另一种胶原基质与双功能肽混合，该双功能肽由对胶原具有高亲和力的结合结构域和对BMP-2具有高亲和力的另一个结构域组成。第一种制剂满足我们的体外功效标准，但未能形成稳定的水凝胶，导致其在我们的体内骨诱导模型中失败。第二个配方，含有双功能BMP-2：胶原蛋白肽似乎满足我们在体外和体内的性能标准。在第1阶段开发的技术，并在第2阶段提出商业优化，代表了一种独特的生物材料，可能适用于许多医疗适应症。我们的第2阶段提案有3个独立的目标：1）优化肽序列和合成，用于商业规模生产和配制; 2）检查每种改性水凝胶的生物相容性、毒性和稳定性; 3）在兔截骨模型中测试我们的可注射载体的体内成骨功效。使用BMP-2的肽结合剂的新递送基质的开发可能允许更大程度的受控生长因子释放。具体而言，可注射的BMP-2制剂将允许用微创手术治疗骨折。广泛应用，注射生长因子可能会增强愈合的生物成分，鼓励更简单的手术干预，更快的愈合和改善的结果。通过将非侵入性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，同时减少其剂量和伴随的费用。（* 3）我们认为这种BMP-2输送平台可以用作其他生长因子的模型，如PDGF-BB，TGF-3或GDF7，Affinergy已经开发了高亲和力结合肽。引导我们的原型BMP-2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：称为骨形态发生蛋白（BMPs）的生长因子目前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，约15%的骨折愈合延迟或受损。然而，目前使用的临床应用需要开放手术以在愈合部位插入载体/BMP组合。通过微创手术递送BMP的能力将具有相当大的临床益处。在这项提案中，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，该系统可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.