Hi @AlexH ,
VIR-3434 is a neutralizing monoclonal antibody that in essence artificially provides some immunity to HBV infection of cells as long as it stays at a high enough level in the body. It is a high-tech version of HBIG that has been approved for many years. It will not provide a cure on its own, but could be really useful in a combination therapy.
VIR-3434 performed well in the Phase I safety trials and is in Phase II (expanded safety/dose assessment and the start of testing efficacy). If the Phase II results are good, the normal pattern is to go into a large Phase III trial that continues to look at safety and tests efficacy. To do so, the Phase II results need to be finalized and evaluated, the Phase III trial needs to be designed based on what was learned in Phase II, and the trial needs to be done. If the Phase III trial is successful, VirBiotec needs to submit new drug applications to the various national regulatory bodies (FDA in the USA, European Medicines Agency for the EU, etc), and the regulatory agencies need to conduct extremely detailed reviews of the application before approval.
There is no guarantee that any drug candidate will survive this gauntlet. In addition to scientific barriers such as insufficient efficacy or safety problems, there are all sort of business and regulatory issues. Can the company raise the tens to hundreds of millions of dollars required to finish the trials and apply for a license? Will the regulatory agencies conclude the drug is “non-inferior” (ie, not worse than) competing licensed drugs? Will Vir Biotec be able to produce the drug at a price cheap enough to allow them to make money (to pay back the ~US$1-2 Billion spent in drug development and then make a profit)? Is the patent protection solid enough to prevent competitors from simply stealing it and selling it on their own?
In short, drug discovery/development is not for the faint or heart! However, I remain very optimistic. There are so many drug candidates for HBV in all stages of development that are looking good for the stage they are at that some of them will certainly make it through to licensure. My guess (and it is only a guess as the pace of science cannot be predicted) is that better therapies will start appearing in 3-5 years, with potential curative therapies in around a decade.
Rest assured, the scientific and medical communities are working as hard as physically possible to improve therapy and develop a cure.