Glioblastoma is the most common and most aggressive primary brain malignancy. The current initial standard of care consists of maximal safe surgical resection followed by radical radiotherapy and adjuvant temozolomide. Despite optimal therapy, median survival is ~15 months from diagnosis in molecularly unselected patients, and <6 months for patients with recurrent disease. Therefore, clinical treatments are currently palliative, not curative. Collectively, current knowledge suggests that the continued tumor growth and recurrence is in part due to the presence of glioma stem-like cells, which display self-renewal and tumorigenic potential. They differ from their more differentiated progeny, as they are more resistant to current treatments. Recurrent disease may be a consequence of the enhancement and/or gain of stem cell-like characteristics during disease progression, together with preferential death of more differentiated tumor cells during treatment, signifying that the cancer stem cell phenotype is a crucial therapeutic target. The limited knowledge of the characteristics of these cells and their response to current clinical treatments warrants intensive investigation with the aim to improve patient survival and/or develop a cure for this disease.

Glucagon is unstable and undergoes degradation and aggregation in aqueous solution. For this reason, its use in portable pumps for closed loop management of diabetes is limited to very short periods. In this study, we sought to identify the degradation mechanisms and the bioactivity of specific degradation products. We studied degradation in the alkaline range, a range at which aggregation is minimized. Native glucagon and analogs identical to glucagon degradation products were synthesized. To quantify biological activity in glucagon and in the degradation peptides, a protein kinase A-based bioassay was used. Aged, fresh, and modified peptides were analyzed by liquid chromatography with mass spectrometry (LCMS). Oxidation of glucagon at the Met residue was common but did not reduce bioactivity. Deamidation and isomerization were also common and were more prevalent at pH 10 than 9. The biological effects of deamidation and isomerization were unpredictable; deamidation at some sites did not reduce bioactivity. Deamidation of Gln 3, isomerization of Asp 9, and deamidation with isomerization at Asn 28 all caused marked potency loss. Studies with molecular-weight-cutoff membranes and LCMS revealed much greater fibrillation at pH 9 than 10. Further work is necessary to determine formulations of glucagon that minimize degradation and fibrillation.

Small doses of glucagon given subcutaneously in the research setting by an automated system prevent most cases of hypoglycemia in persons with diabetes. However, glucagon is very unstable and cannot be kept in a portable pump. Glucagon rapidly forms amyloid fibrils, even within the first day after reconstitution. Aggregation eventually leads to insoluble gels, which occlude pump catheters. Fibrillation occurs rapidly at acid pH, but is absent or minimal at alkaline pH values of ~10. Glucagon also degrades over time; this problem is greater at alkaline pH. Several studies suggest that its primary degradative pathway is deamidation, which results in a conversion of asparagine to aspartic acid. A cell-based assay for glucagon bioactivity that assesses glucagon receptor (GluR) activation can screen promising glucagon formulations. However, mammalian hepatocytes are usually problematic as they can lose GluR expression during culture. Assays for cyclic AMP (cAMP) or its downstream effector, protein kinase A (PKA), in engineered cell systems, are more reliable and suitable for inexpensive, high-throughput assessment of bioactivity.

The role of continuous glucose monitoring (CGM) in type 1 diabetes is well established in improving glycemic control and reducing hypoglycemia. Type 2 diabetes (T2D) is more prevalent than type 1 diabetes and management of type 2 diabetes is more heterogeneous, requiring treatment ranging from lifestyle modification to oral medications to intensive insulin therapy. Recent randomized controlled trials in intensively insulin treated type 2 diabetes demonstrated the efficacy and safety of rtCGM in reducing glycated hemoglobin without increasing hypoglycemia. Though evidence is limited, early studies have indicated a role for rtCGM in selected patients with non-insulin requiring T2D to improve glycemic control and/or reduce hypoglycemia. Based on literature review, we summarized current data on the use of rtCGM in T2D management, and provided future research direction to generate more evidence on the utility of CGM in this population.