A Phase 2 Evaluation of a Novel Co-Formulation of Pramlintide and Regular Insulin to Improve Postprandial Glycemic Control in Adults with Type 1 Diabetes (T1D)

Abstract Objective: Pramlintide co-administration, used in conjunction with prandial insulin, has substantial clinical benefits to improve post-prandial glucose excursions, glycemic variability (GV) and time in range (TIR), but is associated with an increased injection burden that adversely affects adherence and persistence. A novel, fixed-ratio co-formulation of pramlintide and regular insulin (XP-3924) was evaluated in a phase 2 single injection study measuring XP-3924 pharmacokinetics (PK), glucose pharmacodynamics (PD), and its effects upon overall glycemic control. Methods: This was a Phase 2 randomized, open-label, active comparator-controlled, three-period cross-over study, which enrolled 18 adults with T1D to compare the PK and PD, glycemic affects and safety and tolerability of a single dose of XP-3924, to co-administration of regular insulin (Humulin® R) and pramlintide (Symlin®), and to an injection of regular insulin (RI) alone. Subjects were randomly allocated to a sequence of three treatments: XP-3924 (with 50% insulin reduction based their insulin to carbohydrate ratio), RI, or co-administration (RI with 50% insulin reduction plus a comparable pramlintide dose, co-administered as separate injections). The study drugs were administered subcutaneously 30 minutes before a 75-gram oral glucose challenge and glucose levels were monitored for 6 hours. Results: XP-3924 treatment resulted in a 62.3% reduction of hyperglycemia (blood glucose AUC0-3 hr >180 mg/dL) after the glucose challenge when compared to RI (p<0.001), and exhibited comparable postprandial glycemic control to that of the co-administration. After the oral glucose challenge, the mean absolute change in blood glucose and was less in XP-3924 when compared to both co-administration and to RI (197.7±70.74 mg/dL, 230.5±162.39 mg/dL, 254.2±195.21 mg/dL, respectively), as well as GV as defined by the comparison of the intrasubject coefficient of variation of plasma glucose readings across study treatments (53.3%, 62.1%, 71.0%, respectively). The PK of Pramlintide in XP-3924 when compared to co-administration, exhibited longer median Tmax [40.5 (range 21.0–150.0) minutes versus 10.0 (range 10.0–24.0) minutes, respectively], and comparable AUC0-360. The incidence and severity of treatment emergent adverse events (e.g., injection site reactions, minimal nausea and vomiting) was comparable across all treatment arms with no drug-related serious adverse events. Conclusion: XP-3924 was well tolerated and significantly improved post-prandial glucose excursions and glycemic variability compared to regular insulin. XP-3924 also exhibited a favorable PK and PD profile and may be a viable alternative to insulin and pramlintide co-administration to improve treatment adherence and overall glycemic control, especially after meals, addressing an unmet need in the clinical care of people with type 1 diabetes.