Provectus provided an update on research of its investigational immunotherapy PV-10 (rose bengal sodium, a halogenated xanthene small molecule) as an immune adjuvant in vaccines for cancer and viruses to improve immune response upon vaccination, in conjunction with the Company's ongoing efforts to expand its intellectual property. On January 20, 2022, the U.S. Patent and Trademark Office (USPTO) published Provectus' patent application entitled “Halogenated Xanthenes as Vaccine Adjuvants” (publication no. US 202 [1]2 [2]/[3]0016242 [4] A1 [5]), which contained among other things: In vitro data that showed PV-10 was able to significantly increase numbers of interferon (IFN) gamma-producing CD8 cells (compared to controls) for peptides representing various antigenic regions of the Hepatitis B virus (HBV) core protein (HBcAg).

These peptides were selected for their capability to raise CD4 and CD8 T cells against HBV.