Pediatric Oncohematology and Bone Marrow Transplant Unit, Children's Hospital, ASST Spedali Civili of Brescia, Brescia, Italy.
Stem Cell Laboratory, Section of Hematology and Blood Coagulation, Clinical Chemistry Laboratory, Diagnostics Department, ASST Spedali Civili of Brescia, Brescia, Italy.
Transplant Cell Ther. 2021 May;27(5):426.e1-426.e9. doi: 10.1016/j.jtct.2021.01.020. Epub 2021 Jan 24.
Less than 25% of children who require hematopoietic stem cell transplantation (HSCT) for primary immunodeficiencies (PIDs) or genetic hematological diseases have an HLA-identical sibling. For them, a matched unrelated donor (MUD), although baring a greater risk of graft failure, delayed engraftment and immune reconstitution, and severe graft-versus-host disease (GvHD), represents a valid alternative. The stem cell source is also important, as unprocessed peripheral blood stem cells (PBSCs) contain 5 to 10 times more T cells than bone marrow (BM)-derived grafts, a major risk especially for small children with PID. A CD34+ positive selection can mitigate HLA compatibility issues, but the resulting CD3+ T cell depletion hampers engraftment and facilitates infections. To mitigate those problems, we decided to add back a certain number of T cells (30 × 10 cells/kg body weight [BW]) to the positive CD34+ selection derived from MUD BM or PBSCs and report the results in terms of time to engraftment and immune reconstitution, GvHD incidence, infections, and survival. Our aim was to show not only the feasibility and clinical efficacy of this addback but also that PBSC-derived CD34+ selected grafts with calibrated T cell addback would be equivalent to BM-derived grafts. We analyzed retrospectively our single-center cohort of 76 children (median age, 1.9 years) affected by PID (61) and hematological diseases (15) who received a total of 79 MUD HSCTs with CD34+ selection and addback of 30 × 10 CD3+ cells/kg BW between 2001 and 2019. We used descriptive and analytic statistics (chi-square, Student's t-test, Mann-Whitney U test, as appropriate) and constructed Kaplan-Meier curves using the log-rank test to compare patients grafted with BM or PBSC-derived inocula. The two groups showed no statistically significant differences in terms of age, sex, HLA-mismatch, or amount of CD3+ cells/kg BW added back to the CD34+ selection. However, the latter being higher in the PBSC group (P = .0001). Overall engraftment rate was 96% (73/76) and occurred faster in the PBSC group than in BM recipients: polymorphonuclear cells, 16 versus 21 days (P = .006); platelets, 15 versus 22 days (P = .001). GvHD incidence was low. No acute GvHD was diagnosed in 24 children, whereas grades I, II, III, and IV occurred in 19, 28, five, and three children, respectively (P not significant). Chronic GvHD was seen in only two children. The CD4+ count at six months after HSCT was higher in PBSC recipients as compared to those receiving BM (184 versus 88 CD4+ cells; P = .003). Overall survival for the whole cohort was 80% at 10 years, with no significant difference between the two stem cell sources (P not significant). Viral infections occurred among five of the PBSC grafted children and 14 in the BM group (P not significant), and no patient suffered from post-transplant lymphoproliferative disorder (PTLD). The results we present show that an addback of 30 × 10 donor CD3+ cells/kg recipient BW to a MUD BM or PBSC-derived CD34+ selection gives promising results in infants and young children undergoing HSCT for PID or hematological diseases. Furthermore, with this manipulation the inherent limits of PBSC-derived grafts can be overcome, allowing both swift engraftment and immune reconstitution without an increase in GvHD, infections, or PTLD.
接受造血干细胞移植（HSCT）治疗原发性免疫缺陷（PID）或遗传性血液疾病的儿童中，不到 25%有 HLA 完全匹配的同胞供体。对于这些患儿，匹配的无关供体（MUD）虽然存在移植物失功、延迟植入和免疫重建以及严重移植物抗宿主病（GvHD）的风险，但仍是一种有效的替代选择。干细胞来源也很重要，因为未经处理的外周血干细胞（PBSC）比骨髓（BM）来源的移植物中含有 5 至 10 倍的 T 细胞，这对 PID 患儿等年幼儿童是一个主要风险。CD34+阳性选择可以减轻 HLA 配型问题，但由此导致的 CD3+T 细胞耗竭会阻碍植入和增加感染风险。为了减轻这些问题，我们决定在源自 MUD BM 或 PBSC 的 CD34+阳性选择中添加一定数量的 T 细胞（30×10 个细胞/kg 体重[BW]），并报告植入和免疫重建、GvHD 发生率、感染和存活率方面的结果。我们的目的不仅是展示这种添加回输的可行性和临床疗效，而且证明源自 PBSC 的 CD34+选择移植后添加校准的 T 细胞回输与 BM 来源的移植物相当。我们回顾性分析了我们单中心 76 例 PID（61 例）和血液系统疾病（15 例）患儿的队列，这些患儿在 2001 年至 2019 年间共接受了 79 例 MUD HSCT，其中 76 例患儿接受了 CD34+选择和 30×10 CD3+细胞/kg BW 的 T 细胞添加回输。我们使用描述性和分析性统计（卡方检验、Student's t 检验、Mann-Whitney U 检验，视情况而定），并使用对数秩检验构建 Kaplan-Meier 曲线，以比较接受 BM 或 PBSC 来源接种物的患者。两组患者在年龄、性别、HLA 错配或添加回 CD34+选择的 CD3+细胞/kg BW 数量方面无统计学差异。然而，后者在 PBSC 组更高（P=0.0001）。总体植入率为 96%（73/76），PBSC 组比 BM 组更快：中性粒细胞，分别为 16 天和 21 天（P=0.006）；血小板，分别为 15 天和 22 天（P=0.001）。GvHD 发生率较低。24 例患儿未诊断为急性 GvHD，而 19、28、5 和 3 例患儿分别发生 I、II、III 和 IV 级急性 GvHD（P 无显著差异）。仅 2 例患儿发生慢性 GvHD。与接受 BM 移植的患儿相比，PBSC 移植的患儿在 HSCT 后 6 个月的 CD4+计数更高（184 个 vs 88 个 CD4+细胞；P=0.003）。整个队列的 10 年总生存率为 80%，两种干细胞来源之间无显著差异（P 无显著差异）。5 例 PBSC 移植患儿和 14 例 BM 组患儿发生病毒感染（P 无显著差异），无患儿发生移植后淋巴细胞增生性疾病（PTLD）。我们报告的结果表明，向源自 MUD BM 或 PBSC 的 CD34+选择添加 30×10 个供体 CD3+细胞/kg 受体 BW，可以为 PID 或血液系统疾病接受 HSCT 的婴儿和幼儿带来有前景的结果。此外，通过这种操作可以克服 PBSC 移植物的固有限制，既可以迅速植入和免疫重建，又不会增加 GvHD、感染或 PTLD 的风险。
