Accelerated discovery of thermostable vaccines using data-efficient AI

Abstract The inherent instability of mRNA-lipid nanoparticles (LNPs) necessitates ultra-cold storage, creating significant barriers for global distribution and limiting their broader application in advanced delivery systems. Solid-state, water-free formulations offer a promising solution by enhancing thermostability and enabling integration into emerging delivery modalities such as microneedle (MN) patches. Prior efforts to stabilize mRNA-LNPs have been constrained by narrow formulation scope and low-throughput screening methods. Here, we introduce AGENT (Algorithm-Guided Experimental design for lipid Nanoparticle Thermostabilization), an AI-driven framework that couples high-throughput experimentation with Bayesian optimization to rapidly identify thermostable mRNA-LNP formulations. Manual exploration of the formulation space required months of screening and yielded suboptimal candidates. In contrast, AGENT extracted maximal information from sparse experimental datasets, enabling efficient formulation optimization in only six iterations completed within one month. Using AGENT, we stabilized mRNA vaccines with diverse LNPs, including those in clinical use, into solid state formulations that retained 100% bioactivity after storage at 37°C for over two months. The thermostable vaccines induced antigen-specific IgG and germinal center B cell responses that were non-inferior to those elicited by freshly prepared soluble vaccines. The solid-state formulations were further incorporated into dissolvable MN patches and administered to rodents and nonhuman primates, yielding comparable neutralizing antibody titers compared to conventional intramuscular delivery of fresh vaccines. To our knowledge, this study presents the first demonstration of AI-driven design of thermostable RNA vaccines, offering a scalable, cold-chain-free solution for global immunization. By addressing both stability and delivery challenges, AGENT provides a potentially transformative platform for developing accessible next-generation therapeutics.