Characterization of a GPCR-blocking antibody for the treatment of breast cancer.

描述（由申请人提供）：G蛋白偶联受体（gpcr）代表了一个不同的细胞表面受体家族，在几乎所有细胞中介导重要的生物反应。这些反应包括增殖、迁移、组织侵袭和细胞存活。因此，这个大约有700个成员的大家族代表了治疗包括癌症在内的各种疾病的最具吸引力的单一药物靶点家族。大量的工作已经完成，努力产生特定的药物拮抗剂为个别家庭成员，但这种方法的成功已经限制了他们的结构相似性。这使得很难生产出不受脱靶效应影响的合适的选择性化合物。一种提供了无与伦比的特异性潜力的方法是单克隆抗体的发展。然而，由于必须靶向阻断受体激活的关键、暴露的细胞外基序的抗原性差，gpcr历来被认为难以抵抗抗体拮抗。乳腺癌是一种身体和情感上毁灭性的诊断，影响着230多万患有这种疾病的美国人，每天有100多名妇女死亡。尽管随着抗肿瘤药物、激素治疗和靶向治疗的不断发展，这种疾病的预后正在逐渐改善，但许多侵袭性乳腺癌对化疗有耐药性，并导致确诊后5年内10%的死亡率。一种被称为鞘氨醇1-磷酸（S1P）的化合物可能是乳腺癌侵袭性和耐药性的主要决定因素。S1P是一种小分子，通常高浓度存在于血液中，加速乳腺癌的发展。它通过促进癌细胞的生长和扩散，刺激新血管的形成，从而增加肿瘤的氧气和营养供应，从而达到这一目的。有证据表明，这些作用主要是S1P的同源GPCR S1P3受到刺激的结果。由于S1P3已被证明可以促进乳腺癌细胞的生长，并且由于它会导致肿瘤中血管的不受控制的生长，因此阻断S1P3很可能会抑制大多数类型乳腺癌的生长。动物研究表明，这种受体的丧失与不良影响无关，为这种方法的安全性提供了证据。然而，直到最近，还没有关于S1P3特异性拮抗剂的报道。我们之前的工作（1R43CA132400）导致了一种特异性识别S1P3并阻断其激活的单克隆抗体的开发。由于这是首次报道的阻断非细胞因子GPCR的抗体，因此它代表了抗体药物开发的突破。该项目的目标是1)定量验证该抗体的功能功效，2)证明其在体内的活性和生物利用度。

DESCRIPTION (provided by applicant): G protein-coupled receptors (GPCRs) represent a diverse family of cell surface receptors that mediate important biological responses in nearly all cells. These responses include proliferation, migration, tissue invasion, and cell survival. As such, this large, ~700 member family represents the most attractive single family of drug targets for a variety of diseases including cancer. A great deal of work has been performed in an effort to generate specific pharmacologic antagonists for individual family members, but the success of this approach has been limited by their structural similarity. This has made it difficult to produce suitably selective compounds that are not complicated by off-target effects. One approach that offers the potential for unparalleled specificity is the development of monoclonal antibodies. However, GPCRs have historically been considered intractable to antibody antagonism due to poor antigenicity of critical, exposed, extracellular motifs that must be targeted to block receptor activation. Breast cancer is a physically and emotionally devastating diagnosis affecting over 2.3 million Americans living with the disease and killing over 100 women each day. Although the prognosis for this disease is gradually improving with the continued development of antineoplastic drugs, hormonal therapies, and targeted therapies, many aggressive forms of breast cancer are resistant to chemotherapy and result in a 10% mortality rate within 5 years of diagnosis. A compound known as sphingosine 1-phosphate (S1P) may be a major determinant of the aggressiveness and drug resistance of breast cancer. S1P is a small molecule normally present in high concentrations in the blood that accelerates the progression of breast cancer. It does this by promoting the growth and spreading of cancer cells and by stimulating the formation of new blood vessels, thereby increasing the supply of oxygen and nutrients to the tumor. Evidence suggests that these actions are largely the result of the stimulation of a cognate GPCR for S1P called S1P3. Since S1P has been shown to promote growth of breast cancer cells, and since it causes blood vessels to grow uncontrollably in tumors, it is likely that blocking S1P3 will inhibit the growth of most forms of breast cancer. Animal studies suggest that loss of this receptor is not associated with undesirable effects, providing evidence for the safety of this approach. Until recently, however, there were no reports of any specific antagonists for S1P3. Our previous work (1R43CA132400) resulted in the development of a monoclonal antibody that specifically recognizes S1P3 and blocks its activation. Since this is the first-reported antibody to block a non-cytokine GPCR, it represents a breakthrough in antibody drug development. The goals of this project are to 1) quantitatively validate the functional efficacy of this antibody, and 2) demonstrate its activity and bioavailability in vivo. PUBLIC HEALTH RELEVANCE: Breast cancer is the second most common form of cancer in women causing the death of over 35,000 Americans each year. The proposed research will characterize a new drug developed at Expression Drug Designs that interrupts cellular processes known to promote growth of breast tumors, thus limiting cancer growth. Completion of the proposed project will determine if this new drug is likely to be effective in treating breast tumors.