medwireNews: Low-dose anti-thymocyte globulin (ATG) significantly slows the decline in C-peptide levels and reduces glycated hemoglobin (HbA1c) versus placebo in patients with newly diagnosed type 1 diabetes, US study findings indicate.
However, unlike data previously obtained among patients with established diabetes, the use of ATG in combination with pegylated granulocyte colony-stimulating factor (GCSF) did not significantly improve the level of C-peptide preservation, report Michael Haller (University of Florida, Gainesville) and colleagues from the Type 1 Diabetes TrialNet Study Group.
This disparity may be partly due to “[t]he relatively small sample sizes of the pilot ATG and GCSF study as well as this phase IIb effort,” the researchers note.
Haller and team found that the mean C-peptide area under the curve (AUC) during a 2-hour mixed-meal tolerance test 1 year after initiation of therapy was 0.646 nmol/L for the 29 individuals with new-onset (<100 days) type 1 diabetes who were randomly assigned to receive a single course of ATG 2.5 mg/kg.
This was significantly higher than the 0.406 nmol/L C-peptide AUC observed among the 31 patients randomly assigned to the placebo group.
A further 29 study participants were randomly assigned to receive ATG followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for six doses). In this group, the mean C-peptide AUC (0.528 nmol/L) was not significantly different from that of the placebo group.
The investigators also measured HbA1c at 1 year and found that the level was significantly lower with ATG alone and with ATG plus pegylated GCSF, at approximately 6.6% and 6.8%, respectively, than with placebo, at approximately 7.7%.
By contrast, the level of average daily insulin use did not differ significantly among the three groups studied.
A similar number of patients in the ATG and ATG plus pegylated GCSF groups experienced grade 3 serum sickness (15 vs 12) or cytokine release syndrome (zero vs two), but the number of any grade musculoskeletal and connective tissue adverse events was substantially lower with ATG than with ATG plus pegylated GCSF (three vs 10).
Writing in Diabetes Care, Haller et al conclude: “Long-term follow-up of this study cohort will determine the duration of protection afforded by low-dose ATG.”
They add: “Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of [type 1 diabetes].”
By Laura Cowen
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