Process development and safety evaluation of ABCB5 + limbal stem cells as advanced-therapy medicinal product to treat limbal stem cell deficiency

• Published in: Stem cell research & therapy Vol. 12; no. 1; pp. 194 - 21
• Main Authors: Norrick, Alexandra, Esterlechner, Jasmina, Niebergall-Roth, Elke, Dehio, Ulf, Sadeghi, Samar, Schröder, Hannes M, Ballikaya, Seda, Stemler, Nicole, Ganss, Christoph, Dieter, Kathrin, Dachtler, Ann-Kathrin, Merz, Patrick, Sel, Saadettin, Chodosh, James, Cursiefen, Claus, Frank, Natasha Y, Auffarth, Gerd U, Ksander, Bruce, Frank, Markus H, Kluth, Mark A
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 19.03.2021; BioMed Central; BMC
• Subjects: ABCB5; Advanced-therapy medicinal product; Animal models; Animals; Antibodies; ATP Binding Cassette Transporter, Subfamily B - genetics; ATP Binding Cassette Transporter, Subfamily B - metabolism; Cadavers; Cell culture; Cornea; Corneal Diseases - therapy; Drug approval; Epithelium, Corneal - metabolism; GMP manufacturing; Good Manufacturing Practice; Health aspects; Humans; Limbal stem cell deficiency; Limbal stem cells; Limbus Corneae - metabolism; Localization; Manufacturing; Morphology; p63; Patients; Pax6 protein; Process controls; Prospective Studies; Safety; Safety and security measures; Stem cell transplantation; Stem cells; Stem Cells - metabolism; Tissue Distribution; Toxicity; Transcription factors; Transplantation; Transplants & implants; Viral antibodies; United States > US; Germany; Advanced-therapy medicinal product; Limbal stem cells; GMP manufacturing; ABCB5; PAX6; p63; Limbal stem cell deficiency
• ISSN: 1757-6512; 1757-6512
• DOI: 10.1186/s13287-021-02272-2

While therapeutic success of the limbal tissue or cell transplantation to treat severe cases of limbal stem cell (LSC) deficiency (LSCD) strongly depends on the percentage of LSCs within the transplanted cells, prospective LSC enrichment has been hampered by the intranuclear localization of the previously reported LSC marker p63. The recent identification of the ATP-binding cassette transporter ABCB5 as a plasma membrane-spanning marker of LSCs that are capable of restoring the cornea and the development of an antibody directed against an extracellular loop of the ABCB5 molecule stimulated us to develop a novel treatment strategy based on the utilization of in vitro expanded allogeneic ABCB5 LSCs derived from human cadaveric limbal tissue. We developed and validated a Good Manufacturing Practice- and European Pharmacopeia-conform production and quality-control process, by which ABCB5 LSCs are derived from human corneal rims, expanded ex vivo, isolated as homogenous cell population, and manufactured as an advanced-therapy medicinal product (ATMP). This product was tested in a preclinical study program investigating the cells' engraftment potential, biodistribution behavior, and safety. ABCB5 LSCs were reliably expanded and manufactured as an ATMP that contains comparably high percentages of cells expressing transcription factors critical for LSC stemness maintenance (p63) and corneal epithelial differentiation (PAX6). Preclinical studies confirmed local engraftment potential of the cells and gave no signals of toxicity and tumorgenicity. These findings were sufficient for the product to be approved by the German Paul Ehrlich Institute and the U.S. Food & Drug Administration to be tested in an international multicenter phase I/IIa clinical trial (NCT03549299) to evaluate the safety and therapeutic efficacy in patients with LSCD. Building upon these data in conjunction with the previously shown cornea-restoring capacity of human ABCB5 LSCs in animal models of LSCD, we provide an advanced allogeneic LSC-based treatment strategy that shows promise for replenishment of the patient's LSC pool, recreation of a functional barrier against invading conjunctival cells and restoration of a transparent, avascular cornea.