Phase 3 Clinical Trial Candidate Rilparencel Demonstrates Consistent Phenotypic Characteristics during Ex Vivo Culture Expansion Process

Background: A variety of transitional cell states allow for kidney cell replacement. This regenerative heterogeneity challenges the assessment of renal identity. We characterize rilparencel, a renal autologous cell therapy, to elucidate its cellular dynamics during bioprocessing. Methods: Banked source material and drug product samples from the manufacture of rilparencel from kidney biopsies of five patients with T2D and CKD (NCT02836574, investigative clinical trial of T2D with stage 3a-4 CKD) were evaluated using reagents specific for canonical renal cell markers associated with tissue healing. Comparison followed with samples from discarded kidneys (n=3; National Disease Research Interchange) and key reference cells (ATCC). Cell composition was evaluated by flow cytometry using BD FACS Lyric and analysis by FlowJo and FlowSOM. Results: Epithelial cells making up rilparencel maintain their renal identity throughout the manufacturing process, showing colocalization and biological activity of anchored cell markers of the proximal tubule (e.g., GGT, CD13, EpCAM). CD146 expression, a reliable marker of tubular cells, was also confirmed – it is essential for kidney vasculature development (i.e., epithelial and endothelial cell differentiation). This along with data for CD151 and CD156c suggests that rilparencel may play an important role in migration and remodeling within the host tissue. Complementary is the dynamic appearance of an array of key indicators of repair-related biological processes (e.g., self-renewal, regulation of proliferation, cell re-/de-differentiation, and epithelialization, including CD24, CD44, CD90, CD133, CD106, Pax2, and Bmi-1) which may be self-protective against further renal damage in the host patient. Further, there is genomic stability (e.g., cell cycle and DNA content) and absence of cellular senescence (e.g., CD74-negative). Finally, the cell phenotype of rilparencel, manufactured from diseased kidney tissue, resembles that found in batches made from reference control cells. Conclusion: The autologous cell-based therapeutic rilparencel shows a robust potential for successful kidney restoration, providing a roadmap to unveil mechanisms(s) of action. Funding: Commercial Support - ProKidney