Validation of Platelet Expression of FcɣRIIa as a Precision Tool

摘要 美国心脏协会估计，到2022年，约有72万美国人将首次患有冠状动脉疾病。 335，000人将发生复发性事件，其中约87%为缺血性（血栓形成）。抗 血栓治疗降低了缺血性事件复发的风险，但出血发生率较高 并发症血栓形成/缺血风险低的患者应受益于缩短的治疗时间， 高血栓/缺血风险的患者应从更长期的治疗中获得更大的绝对获益， 强效抗血小板治疗目前可用的工具，如临床风险评分和血小板功能检测 不足以有效地个性化心血管护理，有效的精准医学策略， 使临床医生能够瞄准具有高剩余风险的患者。血小板功能测试可有效识别 有风险但在指导治疗的试验中失败的患者。血小板功能的主要弱点 试验包括它们证明了显著的个体内变异性，受两种试验条件的影响 以及患者的治疗，并且他们测量血小板对选择的激动剂的反应性 或一组激动剂。为了解决患者护理中的这一差距，Prolocor在表面上鉴定了一种生物标志物FcγRIIa， 血小板。当血小板活化时，FcγRIIa放大血小板活化。因此，增加的血小板FcγRIIa 增加血小板反应性并利用血小板功能测试的预后意义。相比 目前可用的血小板功能测试，FcγRIIa的表达显示个体内变异性较小， 对与测定条件相关的扰动的敏感性显著降低，并预测血小板反应性增加 对多种激动剂的反应。在对197名患者的初步研究中，考克斯回归分析表明， FcγRIIa的血小板表达是唯一的协变量（风险比3.9，p=0.035）， 当年龄、糖尿病和既往血运重建包括在内时，心脏病发作、中风和死亡风险增加 作为协变量。因此，定量血小板FcγRIIa表达是鉴定心血管风险和 应该可以作为一个强大的精准医疗工具。此后，Prolocor通过开发 结合已用甲醛固定的血小板表面上的Fc γ RIIa的抗体。初始分析 测试显示了极好的精确度（重复测试的变异系数<5%）。拟议的SBIR 旨在根据FDA质量体系提供全面的分析验证 调节，证明血小板Fc γ RIIa表达的测量是准确的，精确的， 可复制的分析验证将与前瞻性观察性研究提供的临床验证配对。 急性冠状动脉综合征、中风和癌症的研究。分析和临床验证相结合 将使Prolocor能够提交Prolocor诊断工具的FDA申请，并允许采用 FcγRIIa作为评估心血管风险的诊断工具应用于心血管医学领域。

ABSTRACT The American Heart Association estimates that, in 2022, about 720,000 Americans will have a first coronary event and 335,000 will have a recurrent event, of which, approximately 87% are ischemic (thrombotic). Anti- thrombotic therapy reduces the risk of recurrent ischemic events at the cost of a greater incidence of bleeding complications. Patients at low thrombotic/ischemic risk should benefit from shortened treatment whereas patients at high thrombotic/ischemic risk should derive greater absolute benefit from longer term treatment with more powerful antiplatelet therapy. Currently available tools such as clinical risk scores and platelet function testing are inadequate to effectively individualize cardiovascular care, and effective precision medicine strategies to enable clinicians to target patients with high residual risk are lacking. Platelet function tests effectively identify patients at risk but failed when used in trials designed to guide treatment. Key weaknesses of platelet function tests include that they demonstrate substantial intra-individual variability, are influenced by both assay conditions as well as the treatment of the patient, and that they measure platelet reactivity in response to a select agonist or group of agonists. To address this gap in patient care, Prolocor identified a biomarker, FcγRIIa, on the surface of platelets. When platelets activate, FcγRIIa amplifies platelet activation. Thus, increased platelet FcγRIIa increases platelet reactivity and leverages the prognostic implications of platelet function tests. Compared to currently available platelet function tests, expression of FcγRIIa shows less intra-individual variability, is substantially less sensitive to perturbations related to assay conditions, and predicts increased platelet reactivity in response to a variety of agonists. In a preliminary study of 197 patients, Cox regression analysis demonstrated that platelet expression of FcγRIIa was the sole covariate (hazard ratio 3.9, p=0.035) associated with an increased risk of heart attack, stroke, and death when age, diabetes, and prior revascularization were included as covariates. Thus, quantifying platelet FcγRIIa expression is a novel method to identify cardiovascular risk and should serve as a powerful precision medicine tool. Prolocor has since refined the assay by developing antibodies that bind to FcyRIIa on the surface of platelets that have been fixed with formaldehyde. Initial analytic testing has demonstrated excellent precision (coefficient of variation of repeated tests <5%). The Proposed SBIR is designed to provide comprehensive analytic validation of the assay in accordance with FDA Quality System Regulation, demonstrating that the measurement of platelet FcɣRIIa expression is accurate, precise, and reproducible. The analytic validation will be paired with clinical validation provided by prospective observational studies in acute coronary syndrome, stroke and cancer. The combination of the analytic and clinical validation will enable Prolocor to submit an FDA application for the Prolocor diagnostic tool, and allow for the uptake of FcγRIIa to the field of cardiovascular medicine as a diagnostic tool for assessing cardiovascular risk.