Live biotherapeutics in the clinic: Regulatory pathways, market dynamics, and future trends.

Live Biotherapeutic Products (LBPs), as defined by the U.S. Food and Drug Administration, are biological products containing live microorganisms intended for the prevention, treatment, or cure of human disease. Distinct from vaccines, their therapeutic effects derive from the biological activity of the living organism itself, including intrinsic functions and, where applicable, metabolites produced in situ. LBPs may originate from human or environmental sources or be rationally designed and are developed, manufactured, and regulated as drugs or biologics for clinical use. Once confined to experimental research, LBPs are now transitioning into approved therapeutics. The approvals of Rebyota and Vowst for recurrent Clostridioides difficile infection mark a pivotal milestone, establishing LBPs as a new therapeutic class. Although the global LBP market currently remains in the tens to low hundreds of millions of U.S. dollars, it is projected to grow at compound annual rates of approximately 13-25 %, with estimates ranging from USD 400 million to 2.6 billion by 2030-2034. Emerging recombinant LBPs further expand this paradigm, enabling enzymatic and peptide drug synthesis and precision delivery platforms. In parallel, regulatory frameworks are evolving, with both the FDA and EMA defining pathways that emphasize quality control, donor sourcing, potency, biosafety, and environmental risk assessment, particularly for genetically modified organisms. Commercial opportunities are driven by unmet needs in gastrointestinal, immune, and metabolic disorders, with potential extension into oncology. Progress, however, is tempered by manufacturing complexity, regulatory burden, reimbursement challenges, public perception, and incomplete mechanistic understanding. Despite these hurdles, the future is compelling, marked by expanding indications, engineered strains, standardized consortia, scalable manufacturing, regulatory harmonization, and accelerating investment.