Historically Based Perspective on the Immunotherapy of Type 1 Diabetes: Where We Have Been, Where We Are, and Where We May Go.

Type 1 diabetes mellitus (T1DM) is an autoimmune condition in which pancreatic β-cells are selectively destroyed, predominantly by autoreactive T lymphocytes. Despite decades of research, the achievement of durable immune tolerance remains elusive. This review presents a historically grounded and forward-looking perspective on the evolution of immunotherapy in T1DM, from early immunosuppressive interventions to advanced precision-based cellular approaches. Specifically, we focus on systemic immunosuppressants (e.g., corticosteroids, cyclosporine), monoclonal antibodies (e.g., anti-CD3, anti-IL-1, anti-TNF), regulatory cell-based approaches (e.g., Tregs, CAR-Tregs, MDSCs), and β-cell replacement strategies using stem cell-derived islets. We analyzed major clinical and translational milestones in immunotherapy for T1DM, with particular attention to the transition from broad immunosuppression to targeted modulation of immune pathways. Emerging data on cell-based therapies, artificial intelligence (AI)-driven stratification, and personalized intervention timing have been incorporated to provide a comprehensive overview of current and future directions. Initial therapies such as corticosteroids and cyclosporine offered proof-of-concept for immune modulation, yet suffered from relapse and toxicity. The introduction of monoclonal antibodies (e.g., teplizumab) marked a shift toward immune-specific intervention, particularly in stage 2 preclinical T1DM. More recent approaches include low-dose IL-2, checkpoint modulation, and antigen-specific tolerance strategies. Cellular therapies such as Treg adoptive transfer, chimeric antigen receptor Tregs (CAR-Tregs), and stem cell-derived islet replacements (e.g., VX-880) have shown promise in preserving β-cell function and modulating autoimmunity. Myeloid-derived suppressor cells (MDSCs), although still preclinical, represent a complementary avenue for immune tolerance induction. Concurrently, AI-based models are emerging as tools to stratify risk and personalize immunotherapeutic timing, enhancing trial design and outcome prediction. : In conclusion, the historical progression from broad immunosuppression to precision-driven strategies underscores the importance of stage-specific, mechanism-based interventions in T1DM. The convergence of targeted biologics, regenerative cell therapies, and β-cell replacement approaches, supported by AI-enabled patient stratification, offers a realistic path toward durable immune tolerance and functional β-cell preservation. Continued integration of these modalities, coupled with rigorous long-term evaluation, will be essential to transform these scientific advances into sustained clinical benefit.