R21 + AS01B (University of Oxford)

R21 + AS01B is a pre-erythrocytic malaria vaccine candidate developed by the Jenner Institute at the University of Oxford. It is a protein subunit vaccine consisting of the R21 antigen—a recombinant fusion protein of the *Plasmodium falciparum* circumsporozoite protein (CSP) and the hepatitis B surface antigen (HBsAg)—formulated with the AS01B adjuvant system. R21 was designed as a next-generation successor to the RTS,S vaccine, utilizing a higher density of CSP on the surface of the virus-like particles to enhance immunogenicity and efficacy. The AS01B adjuvant, a liposome-based system containing the immunostimulants 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and QS-21, is employed to stimulate robust humoral and cellular immune responses against the sporozoite stage of the malaria parasite. While R21 has primarily advanced in clinical development using the Matrix-M adjuvant, the AS01B formulation was evaluated in early-phase clinical trials to assess safety and comparative immunogenicity in healthy adults.

Other names

R21/AS01BR21 with AS01BR-21 with AS01BR 21 with AS01B