Engineering Glucose Responsiveness Into Insulin.

Insulin has a narrow therapeutic index, reflected in a small margin between a dose that achieves good glycemic control and one that causes hypoglycemia. Once injected, the clearance of exogenous insulin is invariant regardless of blood glucose, aggravating the potential to cause hypoglycemia. We sought to create a "smart" insulin, one that can alter insulin clearance and hence insulin action in response to blood glucose, mitigating risk for hypoglycemia. The approach added saccharide units to insulin to create insulin analogs with affinity for both the insulin receptor (IR) and mannose receptor C-type 1 (MR), which functions to clear endogenous mannosylated proteins, a principle used to endow insulin analogs with glucose responsivity. Iteration of these efforts culminated in the discovery of MK-2640, and its in vitro and in vivo preclinical properties are detailed in this report. In glucose clamp experiments conducted in healthy dogs, as plasma glucose was lowered stepwise from 280 mg/dL to 80 mg/dL, progressively more MK-2640 was cleared via MR, reducing by ∼30% its availability for binding to the IR. In dose escalations studies in diabetic minipigs, a higher therapeutic index for MK-2640 (threefold) was observed versus regular insulin (1.3-fold).

Overcoming Challenges With Intravenous Administration of an Investigational Protein Therapeutic.

Piggyback infusion has been widely used in the clinic with most applications in a nonconcurrent fashion for the purpose of administration convenience. In the present study, we demonstrated the application of concurrent piggyback to overcome challenges with intravenous administration of a salt-sensitive investigational protein. This setup consists of a syringe line containing drug admixture prepared in water-for-injection which is connected to a 0.9% sodium chloride line to keep vein open. Both lines are pump controlled and run concurrently at corresponding flow rate. The admixture compatibility study was conducted in 2 stages. In the first stage, admixture (concentration range from 0.05 to 2.0 mg/mL) was demonstrated to be compatible with water-for-injection and administration materials, such as intravenous bag, syringe, and syringe infusion line, for at least 24 h at room temperature. In the second stage, steady-state admixture concentration was demonstrated approximately 10 min after mixing even at the slowest syringe infusion rate. No loss of protein concentration was observed after reaching steady-state infusion. Subvisible particulates before and after piggybacking mixing are found well within the acceptable range.

Application of a high-throughput relative chemical stability assay to screen therapeutic protein formulations by assessment of conformational stability and correlation to aggregation propensity.

In this study, an automated high-throughput relative chemical stability (RCS) assay was developed in which various therapeutic proteins were assessed to determine stability based on the resistance to denaturation post introduction to a chaotrope titration. Detection mechanisms of both intrinsic fluorescence and near UV circular dichroism (near-UV CD) are demonstrated. Assay robustness was investigated by comparing multiple independent assays and achieving r(2) values >0.95 for curve overlays. The complete reversibility of the assay was demonstrated by intrinsic fluorescence, near-UV CD, and biologic potency. To highlight the method utility, we compared the RCS assay with differential scanning calorimetry and dynamic scanning fluorimetry methodologies. Utilizing C1/2 values obtained from the RCS assay, formulation rank-ordering of 12 different mAb formulations was performed. The prediction of long-term stability on protein aggregation is obtained by demonstrating a good correlation with an r(2) of 0.83 between RCS and empirical aggregation propensity data. RCS promises to be an extremely useful tool to aid in candidate formulation development efforts based on the complete reversibility of the method to allow for multiple assessments without protein loss and the strong correlation between the C1/2 data obtained and accelerated stability under stressed conditions.