Ex vivo-expanded highly pure ABCB5+ mesenchymal stromal cells as Good Manufacturing Practice-compliant autologous advanced therapy medicinal product for clinical use: process validation and first in-human data

Abstract

Background aim: Mesenchymal stromal cells (MSCs) hold promise for the treatment of tissue damage and injury. However, MSCs comprise multiple subpopulations with diverse properties, which could explain inconsistent therapeutic outcomes seen among therapeutic attempts. Recently, the adenosine triphosphate-binding cassette transporter ABCB5 has been shown to identify a novel dermal immunomodulatory MSC subpopulation. Methods: The authors have established a validated Good Manufacturing Practice (GMP)-compliant expansion and manufacturing process by which ABCB5 + MSCs can be isolated from skin tissue and processed to generate a highly functional homogeneous cell population manufactured as an advanced therapy medicinal product (ATMP). This product has been approved by the German competent regulatory authority to be tested in a clinical trial to treat therapy-resistant chronic venous ulcers. Results: As of now, 12 wounds in nine patients have been treated with 5 £ 10 5 autologous ABCB5 + MSCs per cm 2 wound area, eliciting a median wound size reduction of 63% (range, 32À100%) at 12 weeks and early relief of pain. Conclusions: The authors describe here their GMP-and European Pharmacopoeia-compliant production and quality control process, report on a pre-clinical dose selection study and present the first in-human results. Together, these data substantiate the idea that ABCB5 + MSCs manufactured as ATMPs could deliver a clinically relevant wound closure strategy for patients with chronic therapy-resistant wounds.

Process data of allogeneic ex vivo-expanded ABCB5+ mesenchymal stromal cells for human use: Off-the-shelf GMP-manufactured donor-independent ATMP

“…Low intra-donor standard deviations and generally narrow inter-donor ranges indicate high homogeneity of the proliferative behavior of the cells within and between the different donors, respectively. This is supported by previous cell division data collected during the process validation phase, which revealed a constant mean division rate of 0.35 divisions per day across 15 donors and even up to 16 passages [7]. It should be noted that the number of isolation cycles (which accounted for up to 11 passages at maximum) for each donor depended on the company's production plan and were, in most cases, not restrained by cell culture-related phenomena such as changes in cell morphology or growing behavior.…”

“…3). The phase distribution pattern (82 ± 6%, 3 ± 2%, and 10 ± 4% for G1, S, and G2/M phase, respectively) resembled extensive data collected during process validation (503 analyses from 260 donors: 72.4 ± 8.5%, 4 ± 2.9%, and 15 ± 8.5% for G1, S, and G2/M phase, respectively) [7] and did not change during passaging until passage 11 (Fig. 3c).…”

“…Human skin, representing a particularly easily accessible tissue that offers the use of surgical discard tissue, harbors a highly potent immunomodulatory cell population marked by the plasma membrane-spanning ATP-Binding Cassette Transporter, Subfamily B, Member 5 (ABCB5) [4]. Human skin-derived ABCB5 + cells display typical MSC characteristics as de ned by the International Society for Cellular Therapy [5], including adherence to plastic surfaces, clonogenicity, expression of CD90, CD73 and CD105, lack of hematopoietic lineage markers CD45, CD34 and CD14, increased osteogenic, adipogenic and chondrogenic differentiation potential as compared with donor-matched ABCB5broblasts [6] and trans-differentiation into CD31 + endothelial cells [7]. In addition to their (trans-) differentiation potential, ABCB5 + MSCs have shown marked immunomodulatory effects through interaction with macrophages [6], neutrophils [8] and regulatory T cells [9], as well as a strong paracrine capacity including adaptive release of vascular endothelial growth factor (VEGF) and interleukin 1 receptor antagonist (IL-1RA) [6,7].…”

“…In preclinical studies, ABCB5 + MSCs delivered signi cant bene t in mouse models of chronic skin wounds [6], epidermolysis bullosa [10] and liver disease [11]. In a rst in-human clinical trial, topically applied ex vivo-expanded ABCB5 + MSCs facilitated wound closure of standard therapy-resistant chronic venous ulcers [7].…”

“…Here we present our expansion and manufacturing process and report on GMP Product Quality Review data for 66 ABCB5 + MSC ("drug substance") batches and 85 nal drug products manufactured between January 2018 and September 2019. While process validation data have been recently published [7], we focus here on the routine GMP manufacturing process of the medicinal product, particularly on process homogeneity, comparability between batches derived from different passages and donors, and potency testing.…”