Multiple Ascending Dose Study of MHS552 in Adults With Type 1 Diabetes Mellitus

Inclusion Criteria: * Adult men and women ages 18 to 45, inclusive, body weight between ≥40 to ≤150 kg, inclusive, with T1DM, a maximum of 5 years from T1DM diagnosis at screening. * Evidence of one or more T1DM autoantibody(ies) including glutamic acid decarboxylase (anti GAD), protein tyrosine, phosphatase-like protein (anti-IA-2); zinc transporter 8 (anti-ZnT8); islet cell (cytoplasmic) (anti-ICA) * Residual pancreatic β-cell function (fasting C-peptide \>100 pmol/L \[0.30 ng/mL\] or random C peptide \>200 pmol/L \[0.60 ng/mL\]) Exclusion Criteria: * History of hypersensitivity to drugs of similar biological class, IL-2 protein analogues, or immunoglobulin (IgG1) proteins, hypersensitivity to any components of the study drug, or history of severe hypersensitivity reaction or anaphylaxis to biological agents, e.g. human monoclonal antibody. * Use of other investigational drugs or use of immunosuppressive agents at the time of enrollment, or within 5 half-lives of enrollment, or until the expected PD effect has returned to baseline, whichever is longer; or longer if required by local regulations. * Diabetes forms other than autoimmune type 1 such as maturity-onset diabetes of the young (MODY), latent autoimmune diabetes of the adult (LADA), acquired diabetes (secondary to medications or surgery), type 2 diabetes by judgement of the investigator. * Diabetic ketoacidosis within 2 weeks. * Polyglandular auto-immune disease, including but not limited to: Addison's disease, pernicious anemia, celiac sprue and psoriasis. Treated, stable Hashimoto's thyroiditis is not exclusionary. * History of capillary leak syndrome (CLS). * Ongoing, and up to 2 weeks prior to screening, initiation of medications or change in dose of medications that may affect glucose control (e.g, systemic steroids, thiazides, beta blockers). Other protocol-defined inclusion/exclusion criteria may apply