Introduction: Induced pluripotent stem cells (iPSC) are promising candidate cells for Beta cell replacement in type 1 diabetes. However, teratoma formation originating from undifferentiated iPSCs contaminating the graft is a critical concern for clinical application.

Undifferentiated iPSC express CD30 surface marker at high levels. Here, we hypothesized that Brentuximab vedotin, which selectively targets CD30 and has already demonstrated its efficacy in a model of cardiac regeneration, induces apoptosis in undifferentiated iPSC while sparing the stem cell-derived beta cells. The final aim is thus to increase the safety of iPSC therapy for diabetes and to prevent teratoma formation upon transplantation.

Methods: The presence of the protein CD30, was tested on eight different iPSC lines, at different steps of differentiation. The effect of monoclonal antibody anti-CD30 Brentuximab vedotin was tested on undifferentiated iPSC and iPSC-derived Beta cells before transplantation to assess the efficiency in CD30-positive cells depletion and in preventing teratoma formation, respectively. Four weeks after transplantation into the kidney capsule of NOD-SCID mice, graft was explanted and the presence of teratoma was evaluated by gross pathology and histological analysis.

Results: Flow cytometry analysis confirmed consistent expression of CD30 in undifferentiated human iPSCs clones (95.33±0.8% in CGTRCiB10, 94.7±0.5% in MODY8, 99.1±0.3% in DRI1, 99.3±0.7% in DRI2 clones). The analysis of the different steps of differentiation revealed that CD30 expression is drastically reduced at DE and PF stages and almost disappeared at the final stages of EN and iBeta.
Addition of Brentuximab vedotin in vitro for 24 hours efficiently induced cell death in human iPSCs. The same treatment with the drug on iPSC-derived beta cells (iBeta) did not kill iBeta nor had an impact on iBeta identity and function. Brentuximab vedotin-treated iBeta maintained unchanged morphology, marker expression and capacity to secrete insulin in response to stimuli.
Transplantation of no-treated human iBeta into NOD-SCID mice consistently induced teratoma formation, with the appearance of teratoma in the graft at 4 weeks post-transplant, whereas iBeta treated with Brentuximab vedotin prior to the transplantation did not form teratoma.

Conclusions: These findings suggest that in vitro treatment with Brentuximab vedotin, targeting the CD30-positive iPSC residual fraction, reduced the tumorigenicity in human iPSC-derived Beta cells, potentially providing enhanced safety for iPSC-based Beta cell replacement therapy in clinical scenarios.