Enhancing Engraftment of Cord Blood by CD26 Inhibition

描述（由申请人提供）：脐带血（CB）移植极大地扩展了患者造血细胞移植（HCT）的可用性，否则这些患者将无法接受这种治疗。与骨髓（BM）和动员外周血（mPB）相比，cbb有几个优点，包括易于收集和安全，现成可用，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）数量少，这导致移植物失败、移植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CD26/二肽基肽酶（DPP） IV活性的机制研究，我们认为抑制CD26/DPPIV将显著提高有限数量的人CB细胞的着床能力，并加快单个CB单位的着床时间。目标1：开展一项多中心II期临床试验，评估西格列汀全身抑制CD26/DPPIV的有效性和安全性，以增强成人血液病患者单个CB单位的植入。假设：通过全身给予CD26抑制剂西格列汀抑制CD26/DPPIV将增强移植，而不会对单个CB移植相关的相对较低水平的GVHD产生负面影响。主要目的：评价移植后30天中性粒细胞恢复的比例，作为移植速度的衡量指标。采用最佳两阶段设计，<50%的患者在第30天植皮将被认为不可接受（零假设；H0: p0<0.5），而70%或更多的植皮将被认为值得进一步研究（备用假设：H1: p1e0.7）。子目标是：a)评估血小板植入时间、患者生存率、移植失败、复发率、急性和慢性GVHD水平；b)通过表型和功能分析，使用相关试验评估免疫细胞的恢复情况；c)评估血液中CD26/DPPIV和造血相关细胞因子的水平。目的2：利用小鼠和人细胞因子的细胞培养和生化研究，以及小鼠BM和人CB的细胞，评估CD26/DPPIV如何机制调节造血。假设：CD26/DPPIV通过其特定的酶切能力截断和灭活不同的造血活性细胞因子来调节造血。我们将在Aim 1中将结果与临床研究进行比较，以更好地理解和利用这种新的治疗方式。子目的包括：a)评估CD26/DPPIV截断GM-CSF、G-CSF、IL-3和EPO的情况，与全长形式相比，细胞内信号；b)确定小鼠全身给予西格列汀是否能增强HSC的归巢并影响细胞因子的产生；c)研究CD26/DPPIV截断和活性的其他分子。

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.