Arecor Therapeutics plc has received positive feedback from the US Food and Drug Administration for its Phase 2 clinical study design of AT278, an ultra-concentrated and ultra-rapid acting insulin formulation designed for use with automated insulin delivery (AID) systems. The Cambridge-based biopharmaceutical company concluded a Type C meeting with the FDA on September 4, 2025, marking a significant milestone in developing what could be the first insulin of its kind tested in combination with AID systems.
Novel Insulin Formulation Targets High-Need Patients
AT278 represents Arecor's proprietary formulation combining ultra-high concentration (500 U/mL) with ultra-rapid action properties. According to the company, AT278 is the only insulin currently in development with the potential to enable longer-wear for high daily insulin users in existing AID systems while supporting future insulin pump miniaturization efforts.
The insulin targets people with both type 1 and type 2 diabetes who have high daily insulin requirements, a growing population with significant unmet medical needs. Sarah Howell, CEO of Arecor, emphasized the potential impact: "We are aiming to establish a new frontier for the treatment of diabetes, and to bring more accessible next generation treatment options, that simplify care and improve outcomes for people living with diabetes."
Accelerated Development Timeline Through TIR Endpoint
The FDA-approved study design incorporates Time-in-Range (TIR) as the primary efficacy endpoint, a strategic decision that could significantly accelerate development timelines. TIR data can be generated over a 6-week dosing period, compared with the minimum 12-week dosing period required for traditional HbA1c measurements.
This endpoint selection will provide real-time information on glycemic variability and, alongside continuous glucose monitoring (CGM)-derived metrics, offer meaningful insights into drug effects to optimize further development. The study design will also generate key data demonstrating patient benefits and economic value of this new treatment option.
Phase 2 Study Design and Timeline
The proposed Phase 2 study will be conducted in the United States as a six-week crossover trial comparing AT278 (500 U/mL) with NovoLog (100 U/mL) in fewer than 100 subjects with type 1 and type 2 diabetes. Continuous glucose monitoring-derived percentage time-in-range will serve as the primary efficacy endpoint.
Arecor plans to submit the Phase 2 Investigational New Drug (IND) application to the FDA during 2026, with enrollment expected to commence later that year, subject to securing additional funding. The company is currently assessing financing options to support the trial.
Building on Positive Phase 1 Results
The Phase 2 study will build upon positive Phase 1 data already generated for AT278 in both type 1 and type 2 diabetes populations. In these earlier studies, AT278 demonstrated superiority to existing insulin products, including NovoRapid (NovoLog in the US) and Humulin R U-500.
Howell noted the significance of the FDA feedback: "Such positive and constructive feedback from the FDA for our first-of-a-kind insulin and AID system combination study represents a significant milestone in our drug development program. We believe we will generate crucial data towards demonstrating the economic value of AT278 in combination with an innovative AID system."
Strategic Partnership Approach
As part of its development strategy, Arecor plans to partner with a US insulin pump company to conduct the Phase 2 study. This collaboration represents a key step toward developing a unique next-generation AID system that addresses current unmet needs in diabetes treatment.
The combination of AT278's dual properties—ultra-high concentration and ultra-rapid profile—positions it to enable next-generation AID systems that could transform diabetes care for patients requiring high daily insulin doses.
