Enhancing Engraftment of Cord Blood by CD26 Inhibition

描述(由申请人提供)：脐带血(CB)移植极大地扩大了造血细胞移植(HCT)的可获得性，这些患者原本不会接受这种根治疗法。与骨髓(BM)和动员外周血(MPB)相比，CB有几个优点，包括采集容易和安全，随时可用，减少急性和慢性移植物抗宿主病(GVHD)。然而，与BM或MPB相比，CB的缺点是有核细胞、造血祖细胞(HPC)和可能的干细胞(HSC)数量较少，这导致移植失败、植入延迟和免疫重建延迟的风险增加。根据我们已发表的实验室和临床前动物模型研究、初步临床数据以及本文报道的CD26/DPPIV活性的机制研究，我们认为抑制CD26/DPPIV将显著增强限制人脐血细胞数量的植入能力，并加快单个CB单位的植入时间。这项多PI赠款提出了以下具体目标：目标1：进行一项多中心II期临床试验，以评估使用西格列汀全身抑制CD26/DPPIV的有效性和安全性，以增强单个CB单位在成人血液病患者中的植入。假设：全身应用CD26抑制剂西格列汀抑制CD26/DPPIV将增强植入，而不会对单个脐带血移植相关的相对较低水平的移植物抗宿主病产生负面影响。主要目的：评估移植后+30天中性粒细胞恢复的患者比例，以此作为植入速度的衡量标准。使用最优的两阶段设计，50%的患者在+30天前移植将被认为是不可接受的(零假设；H0：P0&lt；0.5)，而70%或更多的移植将被认为值得进一步研究(替代假设：h1：p1e0.7)。Subaim是：a)评估血小板植入时间、患者存活、移植失败、复发率、急性和慢性GVHD水平；b)使用相关分析通过表型和功能分析评估免疫细胞的恢复；以及c)评估血液中CD26/DPPIV水平和与造血相关的细胞因子。目的：通过对小鼠和人细胞因子以及小鼠骨髓和人脐血细胞进行细胞培养和生化研究，评价CD26/DPPIV对造血的机械调节作用。假设：CD26/DPPIV通过以下方式调节造血：其特定的酶能力截断和灭活不同的造血活性细胞因子。我们将在目标1中将结果与临床研究进行比较，以更好地理解和利用这一新的治疗方式。Subaim包括：a)评估被CD26/DPPIV截断的GM-CSF、G-CSF、IL-3和EPO如何与全长形式的细胞内信号相比较；b)确定全身应用西格列汀是否增强HSC的归巢并影响细胞因子的产生；以及c)研究CD26/DPPIV截断和活性的其他分子。 公共卫生相关性：脐带血移植是一种可行的治疗方法，但一个缺点是单个脐带血采集中的细胞数量有限，特别是对成年受者来说。通过了解细胞表面酶CD26如何调节血细胞的产生，并通过在脐血移植受者中系统地特异性抑制这种酶，我们相信成年受者的供体细胞植入将得到极大的提高。

DESCRIPTION (provided by applicant): Cord blood (CB) transplantation has greatly extended availability of a hematopoietic cell transplant (HCT) to patients who would not otherwise have received this curative treatment. CB has several advantages over bone marrow (BM) and mobilized peripheral blood (mPB), including ease and safety of collection, ready availability, and lessened acute and chronic graft vs. host disease (GVHD). However, a disadvantage with CB is low numbers of nucleated cells, hematopoietic progenitors (HPC), and likely stem cells (HSC), compared with BM or mPB, which has translated into increase risk of graft failure, delayed engraftment, and delayed immune reconstitution. Based on our published laboratory and preclinical animal model studies, preliminary clinical data, and mechanistic studies on CD26/Dipeptidylpeptidase (DPP) IV activities reported herein, we believe that inhibition of CD26/DPPIV will significantly enhance engraftment capability of limiting numbers of human CB cells, and accelerate time to engraftment of single CB units. This multi-PI grant proposes the following specific aims: Aim 1: Conduct a multicenter phase II clinical trial to assess efficacy and safety of systemic inhibition of CD26/DPPIV using sitagliptin, to enhance engraftment of single CB units in adults with hematological cancers. Hypothesis: Inhibition of CD26/DPPIV by systemic administration of CD26 inhibitor sitagliptin will enhance engraftment, without negatively impacting relatively lower levels of GVHD associated with single CB transplantation. Primary Objective: Evaluate proportion of patients with neutrophil recovery by day +30 after transplant as a measure of speed of engraftment. Using an optimal two-stage design, <50% of patients engrafting by day +30 will be considered unacceptable (null hypothesis; H0: p0<0.5), while 70% or more engrafting will be considered worthy of further study (alternate hypothesis: H1: p1e0.7). Subaims are: a) Evaluate time to platelet engraftment, patient survival, graft failure, relapse rate, acute and chronic GVHD levels; b) Use correlative assays to assess recovery of immune cells through phenotypic and functional analysis; and c) Assess blood levels of CD26/DPPIV, and hematopoietically relevant cytokines. Aim 2: Evaluate how CD26/DPPIV mechanistically regulates hematopoiesis, using cell culture and biochemical studies on mouse and human cytokines and with cells from mouse BM and human CB. Hypothesis: CD26/DPPIV regulates hematopoiesis through: its specific enzymatic capability to truncate and inactivate different hematopoietically active cytokines. We will compare results to clinical study in Aim 1 to better understand and utilize this new treatment modality. Subaims include: a) Evaluate how GM-CSF, G-CSF, IL-3 and EPO truncated by CD26/DPPIV, compared to full length form, signal intracellularly; b) Determine if systemic administration of sitagliptin to mice enhances homing of HSC and influences cytokine production; and c) Study other molecules for CD26/DPPIV truncation and activity. PUBLIC HEALTH RELEVANCE: Cord blood transplantation is a viable treatment, but one disadvantage is the limiting number of cells in single cord blood collections, especially for adult recipients. By understanding how a cell surface enzyme, CD26, regulates blood cell production, and by specifically inhibiting this enzyme systemically in recipients of cord blood transplantation, we believe that donor cell engraftment will be greatly enhanced in adult recipients.