Amongst Janssen’s novel single-dose Covid-19 vaccine candidate of adenovirus platform excipients one might notice a peculiar compound: Hydroxypropyl Betadex (HPBCD). Janssen, holding territorial exclusivity in USA for pharmaceutical use of HPBCD until June 2019, incorporated this cyclodextrin into their monovalent vaccine (first encoded Ad26.COV2.S – now simply called “Janssen Covid-19 vaccine”) composed of a recombinant, replication-incompetent adenovirus type 26 (Ad26) vector, constructed to encode the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein. Other excipients used for the product are as follows: sodium chloride, citric acid monohydrate, polysorbate 80, sodium hydroxide .
The purpose of using HPBCD in Janssen Covid-19 vaccine has not been disclosed in any public document (related patent application has not been published yet), but it is claimed that this Covid-19 vaccine was developed based on the company’s AdVac® vaccine platform. This platform was also used to develop and manufacture Janssen’s European Commission-approved Ebola vaccines (Zabdeno and Mvabea) and to construct its Zika, RSV, and HIV investigational vaccine candidates. Marketed Zabdeno and Mvabea products – however – do not contain HPBCD.
In the patent application of Janssen’s HIV vaccine candidate (WO2017216288) the use of HPBCD is mentioned, however its function is unfortunately not fully justified: “Another formulation buffer that is suitable for recombinant adenovirus comprises 10-25 mM citrate buffer pH 5.9-6.2, 4-6% (w/w) hydroxypropyl-beta-cyclodextrin (HBCD), 70-100 mM NaCl, 0.018-0.035% (w/w) polysorbate-80, and optionally 0.3-0.45%) (w/w) ethanol.” It may be anticipated though, that HPBCD acts as a effective protein stabilizer hindering aggregation and adsorption onto the container wall.
Decision on the approval of the Janssen Covid-19 vaccine candidate may be expected in mid-March in EU (conditional marketing authorisation) and late February in US (emergency use authorization).
 Mariana C. Castells and Elizabeth J. Phillips: The New England Journal of Medicine 2021; 384: 643-9.