Abstract 4138738: Clinical Evidence of Immune Response to Transplanted Allogeneic iPS Cell-Derived Cardiomyocytes

Background&Purpose: The clinical application of cell transplantation therapy utilizing induced pluripotent stem cells (iPS cells) for heart failure is progressing, with the primary strategy being the use of pre-prepared allogeneic iPS cells. The immune response to these transplanted cells is crucial and may affect therapeutic efficacy, necessitating the use of immunosuppressive drugs. However, detailed clinical reports on immune responses are sparse. This study aims to analyze the immune response to transplanted cells in clinical iPS cell-derived cardiomyocyte (iPSC-CM) transplants and examine the correlation between immune response and therapeutic efficacy. Methods: In the "Phase 1 multicenter clinical trial of transplantation of iPSC-CMs for ischemic cardiomyopathy" (https://jrct.niph.go.jp/en-latest-detail/jRCT2053190081), conducted as the First-in-Human trial, the immune response to transplanted cells was analyzed in four cases at our hospital. Comprehensive analysis of anti-human leukocyte antigen (HLA) antibodies in serum and single-cell RNA sequencing in peripheral blood mononuclear cells was performed to investigate their relationship with therapeutic effects on cardiac function. Results: Patients received immunosuppressive drugs (tacrolimus, mycophenolate mofetil, and steroids) for 3 months post-transplantation, followed by a 1-year follow-up. In all cases, an increase in transplant cell HLA-specific antibodies was observed after discontinuing immunosuppressive drugs (Figure 1 and 2). Single-cell analysis revealed a decrease in immunocompetent cells in peripheral blood during immunosuppressive therapy. Cardiac function analysis showed improvements in all cases except Case 2 (Figure 3), where pre-existing anti-HLA-DQ antibodies were present before transplantation. Conclusions: No immune response to the transplanted cells was observed during immunosuppressive therapy. In a case with limited therapeutic response, pre-existing antibodies to transplanted cells were detected, potentially impacting the therapeutic outcome.