Identifying a stable bulk dmLT adjuvant formulation at a clinically relevant concentration

Area of Science:

• Vaccinology
• Biochemistry
• Formulation Science

Background:

• Double mutant heat-labile toxin (dmLT) is an emerging vaccine adjuvant.
• Current dmLT formulations require high dilution for vaccine use, leading to material waste.
• Need for a stabilized dmLT formulation at a clinically relevant concentration.

Purpose of the Study:

• To improve the stability of bulk double mutant heat-labile toxin (dmLT) at a higher concentration (20 µg/mL).
• To achieve this with minimal modifications to the existing dmLT formulation.
• To evaluate the impact of excipient addition on dmLT stability.

Main Methods:

• Lyophilization of dmLT formulations.
• Short-term accelerated stability studies at elevated temperatures (40°C).
• In vitro assessment of dmLT stability post-formulation and lyophilization.

Main Results:

• The addition of 0.05% polysorbate 80 (PS80) to the dmLT formulation enhanced stability.
• Lyophilized dmLT at 20 µg/mL with PS80 remained stable for 4 weeks at 40°C.
• PS80 was identified as a key excipient for stabilizing dmLT.

Conclusions:

• A modified dmLT formulation containing 0.05% PS80 demonstrates improved stability at a clinically relevant concentration.
• This formulation strategy can reduce adjuvant wastage and facilitate vaccine development.
• Further studies are warranted to confirm long-term stability and in vivo efficacy.