Behind the Scenes of Sabin’s Marburg and Sudan Ebolavirus Vaccine Clinical Trials

It’s been a busy year for the Sabin Vaccine Institute’s Research & Development (R&D) team, with two separate vaccine candidates starting Phase 2 clinical trials in two countries (Uganda and Kenya). Here Norman Waters, senior director, clinical operations, and Casey Storme, senior project manager, R&D, share Sabin’s approach to testing these much-needed vaccines for the highly lethal Marburg virus and Sudan ebolavirus diseases, so that the vaccines are safe and effective for diverse populations.

There were outbreaks of both Marburg virus disease and Sudan ebolavirus disease in Africa within the last couple of years. Has that inspired vaccine development for these diseases because there are no approved vaccines yet?

Norm: Sabin is leading the charge on these vaccines. There are not many others working on these vaccines.  Marburg and Sudan ebolavirus diseases appear episodically and leave a trail of death and disability in their wake.  The challenge in developing a vaccine for diseases like these is that you are developing something that is most likely to be used during outbreaks – these diseases are not everyday occurrences. For a vaccine against Marburg or Sudan ebolavirus, the commercial incentive is low but if the vaccine is proven to be safe and effective, it can save lives and prevent the next outbreak.

Is that why Sabin is involved?

Norm: When we first went to the clinical trial sites, they thought Sabin was a pharmaceutical company or a biotech. We said, “no, we’re an NGO (Non-Governmental Organization).” And that sends a different message, that we are mission-based, and that our goal is to reduce death and suffering from vaccine-preventable diseases. When an outbreak occurs, these viruses are extremely contagious and so they can spread through the community. And we’re starting to see more and more of these outbreaks.

Why did you pick research facilities in Uganda and Kenya for the clinical trials?

Casey: Marburg and Sudan ebolavirus outbreaks have occurred in these East African countries in the past. So, by partnering with institutes in these countries to conduct these trials we are able to evaluate these vaccines in the locations where these vaccines are most likely to be deployed in the event of a future outbreak.

We are fortunate to be leveraging years of local and global investment in clinical research capacity from other disease areas like HIV and malaria. Our clinical trial site partners at the Makerere University Walter Reed Project (MUWRP) in Kampala, Uganda, and the Kenya Medical Research Institute (KEMRI) in Siaya, Kenya   have the expertise and the skilled clinical research and lab staff to   conduct these Phase 2 trials. The team at MUWRP has been involved in a number of Ebola vaccine trials over the years, including holding a Phase 1 trial of the Sudan ebolavirus vaccine candidate that Sabin is advancing.

What does the clinical trial entail?

Norm: For each of the Marburg and the Sudan ebolavirus Phase 2 trials, we’re enrolling 125 subjects across the two different sites, half in Uganda and half in Kenya. The study is composed of two different cohorts. We’re studying the vaccine on 18-to-50-year-olds, and then on an older cohort of 50-to-70-year-olds.  After we vaccinate the participants, we perform blood draws at 29 days to assess immunity markers. We then follow the participants for one year or so.

Around six months after the 29-day assessment, we plan to generate an interim assessment of the vaccine’s safety and immunogenicity. This analysis will help us evaluate study success and plan for the next round of research.

How are participants recruited?

Norm: We visited both laboratories and had conversations with the staff who showed us around their facilities. On the second day, the site staff took us out to the community where they’re going to recruit subjects for this study. We visited leaders of the local community and explained what we were doing. Once the leaders are on board, it improves the likelihood of community members wanting to enroll in the study because they understand the benefit if the vaccine works.  In fact, we’ve already completed recruiting at both sites for the Marburg Phase 2 trial. Now we’re in the first stages of the Sudan ebolavirus trial. (Editor’s Note: Since this interview, participants have been recruited and dosed for the Sudan trial as well.)

What are the next steps if the Phase 2 trials in Africa are successful?

Norm: We are already planning a follow-on Phase 2 study in the U.S. for both the Marburg vaccine and Sudan ebolavirus vaccine. While these vaccines are at present more likely to be needed in Africa, there is always a possibility there could be a future outbreak elsewhere, including in the U.S. So, we need to know how well they work in other populations.