During the middle of last month, VBI Vaccines, Inc. (VBIV) announced a phase 3 clinical program for its lead hepatitis B asset, Sci-B-Vac. The program, and perhaps rightly so, is picking up a considerable amount of attention and VBI now has a clear path to commercialization in three major markets for the vaccine in question. Shortly after its releasing of the details for this program, however, the company also released news related to the ongoing development of one of its deeper pipeline assets. Perhaps because of the impact of the Sci-B-Vac news, markets seem to have overlooked the latter release.

Here is a look at what was missed and what it might mean for VBI and its shareholders going forward.

The release details interim data from a phase 1 study of a preventative cytomegalovirus (CMV) vaccine. For those not familiar with this company, VBI has developed a technology called the enveloped Virus like Particle (eVLP) platform. The platform is designed to allow for the creation of a new generation of vaccines; vaccines that seek to improve on the immunogenicity of current standard of care options or that aim to serve as a preventative option in areas of healthcare for which there currently exists no alternative treatment. They seek to achieve this by mimicking as closely as possible the virus against which they are trying to protect the individual being dosed.

With its eVLP platform, VBI is able to achieve this goal through a couple of different avenues. First, and primarily, the vaccines that the platform creates express numerous antigens associated with the target virus. The more antigens that are present, the more the vaccine looks like the virus to the immune system and the more antibodies the immune system creates that will then target the virus on infection. Second, the virus is constructed using mammalian cells as opposed to the plant cells used to construct many current standard of care vaccines. The mammalian nature of the vaccine, just as with the multiple antigen approach, serves to increase the similarity between a virally infected host cell and the preventative vaccine that VBI has created and with which patients are treated.

So, in this instance, the vaccine is called VBI-1501A and – as mentioned – it is targeting CMV. Specifically, the company is trying to develop VBI-1501A as a preventative vaccine. For those not familiar with this space, these sorts of vaccines (as their name suggests) are administered in anticipation of the patient in question becoming infected with, in this case, the CMV virus. The aim is to allow the immune system to develop a collection of antibodies specific to the CMV virus ahead of any infection so that when a patient is infected (if they are, of course) the antibodies required to recognize the virus and to kick start the immune system into attacking and removing it are already in place.

The concept is no different from that which underpins the MMR (measles, mumps, rubella) or the DTP (diphtheria, tetanus, pertussis) vaccines administered to millions of individuals in the US every year. What does differ here, however, is that currently no preventative CMV vaccination is available on the market. This is true despite CMV being one of the most serious and most prevalent newborn infections in the US, with more than 5,000 babies developing problems (ranging from blindness to developmental delays) every year.

The latest data, as mentioned, derives from a phase 1 study and, in particular, a pre-planned interim analysis of said study. The study is primarily set up to address safety (as is generally the case with the sort of early-stage phase I investigations) but is also designed to offer insight into potential efficacy by way of certain immunogenicity signals.

In total, the study enrolled 128 CMV-negative subjects, aged 18-40 years, who were randomized into five arms to receive various dose levels of a modified form of gB, gB-G, with or without the adjuvant alum, or placebo (gB, gB-G here refers to the antigen that the vaccine expresses and that is associated with the CMV virus). The four arms of the study that were given active vaccine received either 0.5mcg of gB-G content with and without alum or 1.0mcg of gB-G content with or without alum.

Patients were vaccinated at zero, two and six months and – as of May this year – all patients have been dosed with their final vaccination.

So what did the numbers tell us?

First and foremost, that the vaccine is safe and was well tolerated at all doses, with no safety signals reported. That's the important but somewhat more boring side of the release. What is more interesting is the efficacy signals that the data produced. The vaccine induced antibody responses against the antigen and, importantly, these responses were dose-dependent after the second vaccination. This is a strong, albeit early-stage, hint of this vaccine working.

Further, in patients that were given the highest dose of the vaccine, and after two doses, seroconversion rate was 100%. Seroconversion here refers to the time taken for a vaccine to induce the creation of antibodies that are at detectable levels in the blood. At a 100% seroconversion rate, therefore, all patients given the highest dose vaccine had levels of CMV antigen associated antibodies in their blood at detectable levels after just the second dose.

Again, an early but very strong efficacy signal.

So what is next?

This was interim data and the next major milestone for VBI (with regards to this program) is topline release. There are two primary elements to this topline readout. The first addresses safety data at day 336 (in other words, what amounts to one year after dosing) and efficacy data as measured after dosing completion (i.e. all patients having received three doses).

Both of these reports should come during the first half of 2018 – they will likely hit press as a combined release. If they are as indicative of safety and efficacy as the most recent release, markets are going to start paying a lot more attention to this program than currently seems to be the case.

Of course, the phase III program will likely take center stage during the coming twelve months but this CMV program offers a longer term set of catalysts that could serve to compound any strength seen on the back of said pivotal program maturing to successful completion.