Curevo's Amezosvatein Shows Promise in Phase 2 Trial, a Step Closer to Developing a More Tolerable Shingles Vaccine

Curevo Vaccine is a US-based biotechnology company aiming to develop a shingles vaccine with better tolerability. Now, Curevo has announced they are a step closer to their goal, sharing positive topline from a Phase 2 trial in which their shingles vaccine candidate amezosvatein (CRV-101) demonstrated non-inferiority to GSK's Shingrix.

Shingles, also known as herpes zoster, affects 1 in 3 Americans at some point in their lives. Shingles causes a painful rash as a result of the varicella-zoster virus (the same virus that causes chickenpox) becoming reactivated later in life.

Shingles can affect people of all ages, but the condition and its potential long-term complications are more common in adults over 50 and those with weakened immune systems. The most prevalent complication is post-herpetic neuralgia, which causes lingering pain or burning sensations in up to 18% of cases. Other complications may include skin infections, inflammation in the lungs or brain, and problems with vision and hearing.

To date, two shingles vaccines have been marketed in the United States: Zostavax, approved in 2006, and Shingrix, approved in 2017. These vaccines have been shown to reduce the risk of shingles as well as lessen its severity. Currently, the CDC recommends a two-dose series of Shingrix to prevent shingles and related complications in adults 50+ and certain other adults with weakened immune systems. However, Zostavax is no longer available for treatment.

Despite the evidence and CDC recommendation, around two-thirds of older adults have not received a shingles vaccine.

“Despite Shingrix being available for several years, vaccine coverage rates remain disappointingly low,” Guy De La Rosa, MD, Curevo’s Chief Medical Officer, stated in a press release. “A growing body of evidence suggests tolerability issues contribute to both vaccine hesitancy and avoidance of the required second dose.”

Amezosvatein is a non-mRNA, adjuvanted subunit vaccine being developed by Curevo. It works by targeting toll-like receptor 4 (TLR4) to boost the immune response against shingles.

The Phase 2 trial enrolled 876 participants, with 257 participants receiving Shingrix and 619 participants across five study arms receiving amezosvatein. The vaccines were administered on an identical schedule of two doses, given two months apart. Amezosvatein met all primary endpoints and demonstrated non-inferiority to Shingrix. The vaccine achieved a 100% vaccine response rate, compared to 97.9% for Shingrix. Additionally, amezosvatein demonstrated lower rates of adverse events.

Overall, amezosvatein had comparable immune responses and lower rates of adverse events compared to Shingrix. In light of the promising results, global Phase 3 trials are planned to start this year to further evaluate the vaccine.