Teplizumab in Stage 2 Type 1 Diabetes: Clinical Practice Experience on Feasibility in 3 Adult Patients

Aim: To describe the first Italian experience with teplizumab administered under a compassionate use programme for adults with Stage 2 type 1 diabetes (T1D), and to evaluate its feasibility, safety and early metabolic outcomes in a real-life clinical setting outside formal clinical trials. Materials and Methods: Three adult women (aged 20–40 years) with Stage 2 T1D, identified through islet autoantibody screening and dysglycaemia assessment, received a 14-day intravenous course of teplizumab (Tzield) in a day-hospital setting. Infusions were managed by a multidisciplinary team with standardised pre-medication and monitoring. Clinical and laboratory parameters (vital signs, lymphocyte count, liver enzymes, HbA1c, C-peptide, continuous glucose monitoring metrics) were recorded at baseline and after 3 months. Results: Treatment was overall well tolerated. One patient developed mild transient elevation of transaminases and lymphopenia, resolving spontaneously. A second patient experienced a 40% reduction in lymphocyte count without symptoms. The third developed a mild cytokine-release syndrome on Day 5, which resolved with supportive therapy but led to treatment discontinuation due to anxiety. At 3-month follow-up, all patients maintained stable glycaemic control and preserved β-cell function. Conclusions: Teplizumab administration under compassionate use proved feasible and safe in a real-life academic context, consistent with pivotal trial data. The experience underscores the importance of a structured multidisciplinary approach, integrating endocrinologists, anaesthesiologists, nurses and psychologists to optimise adherence, safety and patient engagement during early disease-modifying immunotherapy in presymptomatic T1D.