As we look back on the Congress in Europe and forward to future events, a conversation with Dr Andrew Vaillant of Replicor links our event in Barcelona to the World Vaccine and Immunotherapy Congress in San Diego. As Chief Scientific Officer with 20 years’ experience, he has pioneered Replicor’s nucleic acid polymer (NAP) technology. With a focus on hepatitis B (HBV), his insight into therapeutic development is particularly interesting.  

Unique challenges for HBV

We asked Dr Vaillant about the considerations that are required for HBV therapies, and he outlined several “unique challenges” for us. Firstly, the “production of a very large excess of non-infectious subviral particles (HBsAg)” hinders the immune response to HBV. Therefore, the processes involved in vaccine responses are also affected. A successful approach must “occur with the clearance of these particles”. The next challenge is that HBV “exists as a population of thousands of quasispecies all with varying immunoreactivities” as well as “immune escape potential”. Thus, vaccine candidates must “focus on engendering multiple different HBsAg-reactive T-cell species”.  

As Replicor will be presenting at the World Vaccine and Immunotherapy Congress later this month, we asked for a sneak preview of what that might involve. Dr Vaillant graciously gave us an insight! He indicated that we can expected to learn more about “how the industry is faring in achieving” therapy milestones. On top of this, we will hear updates from Replicor’s access programme for REP 2139-Mg in “patients with chronic hepatitis B and D infection with very advanced liver disease”.  

REP 2139-Mg

REP 2139-Mg may have caught your attention, and we heard it is “unique and industry-leading” so we wanted to find out why. It’s Replicor’s “lead drug in development for the treatment of chronic HBV and HDV infection”. It is unique in its ability to “directly” target non-infectious subviral particles. 

“When combined with immunotherapy, REP 2139-Mg is achieving high rates of HBsAg loss and functional cure of both HBV and HDV infection. These are outcomes not achievable with currently approved therapies or with any other technologies currently in development.”

A wider lens

After we had asked Dr Vaillant to explain some of the finer points of Replicor’s work we took a broader approach. We asked about challenges that therapeutic developers are facing, and how they can be overcome. Dr Vaillant recognises that although Replicor is “not directly focused” on an HBV vaccine, a “properly designed therapeutic vaccine” would play an important role in “achieving functional cure of HBV”.  

“With its unique platform of nucleic acid polymers (NAPs) such as REP 2139-Mg, Replicor is in a unique position to remove the immunoinhibitory HBsAg from patients to potentiate a vaccine response.”

In collaboration with vaccine companies, Replicor is pursuing suitable candidates to work “in combination” with REP 2139-Mg for “high rates of functional cure”. Technology evidently plays a huge role in Replicor’s work, but interestingly Dr Vaillant believes “all the technology needed is in place” already.  

“We are focused on educating the field about how to use this technology to develop appropriately broadly HBsAg specific vaccines essential for functional cure of HBV.”

Disruptions and distractions

Our final question was on the issue of COVID-19, which has influenced the work of many of our speakers, whether direct or indirect. For Dr Vaillant, the pandemic “has taken the focus away from many diseases which also take millions of lives each year”.  

“Chronic HBV infection is a disease which affects more than 300 million people worldwide and kills more than 1 million people each year. This death rate is rising due to the important and unmet medical need in this disease.”

Looking forward, Dr Vaillant hopes that “appropriate attention” will return to “other infectious diseases” like HBV and HDV, to “allow faster progress in the field”.  

We are very grateful that Dr Vaillant took the time to answer some of our questions and to give us a preview of Replicor’s presentations at the World Vaccine and Immunotherapy Congress in November. We look forward to hearing more then and hope you will join us