DiaPep277 is a stable version of Heat-shock protein 60 (p277). HSP60 was shown to be important for the induction of diabetes in the non-obese diabetic mouse. DiaPep277 promotes anti-inflammatory effects and cell adhesion, inhibiting migration and skewing cytokine secretion away from an inflammatory response, through its interaction with Toll-like receptor (TLR) 2. Glucagon-stimulated C-peptide production was the primary endpoint of a randomized, double-blind, phase II trial, while secondary endpoints were metabolic control and T-cell autoimmunity against HSP60 and p277. At 10 months, β-cell preservation was seen in the treated group, as shown by better maintained C-peptide concentrations and lower exogenous insulin usage, in comparison to placebo-treated subjects. The DiaPep277-treated individuals also displayed an enhanced TH2 cytokine profile to HSP60 and p277. Despite these promising results and being safe and well-tolerated in children and adults, several subsequent DiaPep277 clinical trials resulted in modest, if any, effects on β-cell preservation. The development of DiaPep277 has been temporarily halted due to the manipulation of phase III trial data.