Safety and preliminary efficacy of allogeneic bone marrow-derived multipotent mesenchymal stromal cells for systemic sclerosis: a single-centre, open-label, dose-escalation, proof-of-concept, phase 1/2 study

Background: Systemic sclerosis (SSc) is a chronic autoimmune disease. We tested the safety of a single intravenous injection of intrafamilial allogeneic bone marrow-derived mesenchymal stromal cells (BM-MSC) to treat severe SSc. Methods: We conducted the first prospective, monocentric, dose-escalation, phase I/II clinical trial investigating the feasibility and safety of a single allogeneic BM-MSC infusion in 20 severe SSc patients who were refractory or had a contraindication to conventional immunosuppressive therapy or autologous hematopoietic stem cell transplant. Patients were assigned to an infusion of either 1x10^6 BM-MSC/kg or 3x10^6 BM-MSC/kg obtained from 20 independent intrafamilial donors. Primary endpoint was the rate of grade ≥ 3 Severe Adverse Events (SAE; NCI Common Terminology Criteria for Adverse Events (v5.0)) in the first 10 days post-BM-MSC infusion. Secondary endpoints included adequacy of BM-MSC production, medium-term SAE, as well as clinical and immunological response. Findings: No Grade 3 ≥ SAE occurred in the first 10 days following MSC infusion in the 20 SSc patients. A significant improvement in modified Rodnan Skin Score (p<0.0001) was observed after BM-MSC infusion, which peaked at 3 months and was sustained for 1 year. No changes in health-related quality of life or pulmonary function were observed. CD8pos T-Cell and NK cell counts slightly increased after infusion (p<0.05) and two patients developed de novo donor-specific anti-HLA. Circulating TGF-β level at baseline was significantly higher in non-responder compared to responder patients (p<0.05). A pattern of low IDO activity, CCL2 production, and HLA-DR expression in BM-MSC batches under in vitro stimulation by IFN-beta was associated with a lack of clinical response in recipient SSc patients. Interpretation: A single infusion of allogeneic BM-MSC transplant was safe in severe SSc patients and triggered short-term disease modifying effects. Clinical response was associated with both the recipients biological features and the functional properties of infused BM-MSC. An aliquot of passage #1 BM-MSC derived from 17 healthy donors were collected prior to infusion in the recipient and cryopreserved analyzed for RNA sequencing.

背景：系统性硬化症（Systemic sclerosis, SSc）是一种慢性自身免疫性疾病。本研究评估了单次静脉输注家族异体骨髓间充质基质细胞（bone marrow-derived mesenchymal stromal cells, BM-MSC）治疗重度SSc的安全性。
方法：本研究开展了第一项前瞻性、单中心、剂量递增的I/II期临床试验，针对20名对传统免疫抑制治疗难治或存在禁忌证、亦或无法接受自体造血干细胞移植的重度SSc患者，探究单次异体BM-MSC输注的可行性与安全性。患者被分配接受1×10^6 BM-MSC/kg或3×10^6 BM-MSC/kg的输注方案，所用细胞取自20名独立的家族供者。主要终点为BM-MSC输注后前10天内≥3级严重不良事件（Severe Adverse Events, SAE；美国国家癌症研究所不良事件通用术语标准v5.0, NCI Common Terminology Criteria for Adverse Events v5.0）的发生率。次要终点包括BM-MSC制备的充分性、中期严重不良事件，以及临床与免疫学应答情况。
结果：20名SSc患者在MSC输注后的前10天内均未出现≥3级严重不良事件。BM-MSC输注后，患者的改良Rodnan皮肤评分显著改善（p<0.0001），该改善于3个月时达到峰值，并持续至1年。未观察到健康相关生活质量或肺功能的变化。输注后，患者的CD8阳性T细胞（CD8pos T-Cell）与NK细胞（natural killer cell, NK）计数轻度升高（p<0.05），另有2名患者出现新发供者特异性抗HLA（human leukocyte antigen）抗体。基线循环转化生长因子-β（transforming growth factor-β, TGF-β）水平在无应答者中显著高于应答者（p<0.05）。在体外经干扰素-β（IFN-beta）刺激后，部分BM-MSC批次呈现出低吲哚胺2,3-双加氧酶（indoleamine 2,3-dioxygenase, IDO）活性、CC趋化因子配体2（CC chemokine ligand 2, CCL2）产生量减少以及HLA-DR表达降低的模式，该模式与受体SSc患者的临床应答缺失相关。
解读：单次异体BM-MSC输注在重度SSc患者中具有安全性，并可触发短期的疾病修饰效应。临床应答与受体的生物学特征以及输注的BM-MSC的功能特性均存在关联。在为受体进行输注前，我们收集了17名健康供者来源的第1代BM-MSC的等分样本，将其冷冻保存后用于RNA测序（RNA sequencing）分析。