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After Prostvac flop, Bavarian Nordic showcases 6-month RSV data

Bavarian Nordic is ready to turn the page after its key cancer vaccine candidate Prostvac failed a phase 3 study, wiping off half its share price. The vaccine specialist is touting six-month data on its its candidate against RSV, simultaneously rolling out a new plan for an RSV challenge study.

 At a six-month followup, investigators are still finding persistent antibody response against multiple RSV targets in participants vaccinated with the MVA-BN vaccine. The findings are in line with investigators’ observations at the three-month mark.

MVA-BN RSV uses a vectored technology different from that used in Prostvac. Earlier results from the 421-subject study in the U.S. showed that most participants experienced 5- to 10-fold T-cell responses over placebo one week after vaccination, and 2- to 4-fold antibody responses after two weeks.
Apart from the original plan to follow these healthy adults aged 55 and older for another six months to evaluate the vaccine’s long-term immunogenicity, Bavarian Nordic is now also planning a human challenge study. The study, slated to start in the second half of 2018, will give researchers an idea of the vaccine’s efficacy prior to a phase 3 trials, assisting them in the planning and design of late-phase trials, the company said.
The Danish company has partnered with a global CRO to develop the challenge model. It said in a release that the company has developed a primary isolate of RSV, which has a level of virulence on par with viruses circulating naturally outside of the lab. Bavarian Nordic didn’t reveal the identity of the CRO, and CEO Paul Chaplin only said in a statement that the CRO “is an ideal partner and a leader in the field having previously been successful in developing a virulent influenza challenge model.”
Also working to nab a share out of a potential $6 billion RSV vaccine market is Novavax, which in July posted positive topline data from a new 300-subject phase 2 study, tentatively confirming a way forward to pair the vaccine with an adjuvant to secure better efficacy. Novavax’s vaccine previously failed a large-scale phase 3 because of what the company called a weak RSV season. Because of that lesson, Bavarian Nordic said it will not limit its phase 3 to just one RSV season.
The new six-week RSV data came just days after Bavarian Nordic pulled the plug on its Bristol-Myers Squibb-partnered cancer vaccine Prostvac as a standalone therapy, as it decided that continuing a phase 3 would be futile. Shares in Bavarian Nordic fell more than 50% following the news at the time. Now, Prostvac’s future lies only in its possibility of being paired up and enhancing the effect of other immuno-oncology agents.