Curevo Announces Positive Updated Phase 2 Data For Amezosvatein Shingles Vaccine

(MENAFN- EIN Presswire) -- One year after the second vaccine dose, the anti-gE antibody immune response to amezosvatein continues to be non-inferior to Shingrix

SEATTLE, Jan. 12, 2025 (GLOBE NEWSWIRE) -- Curevo Vaccine (Curevo), a privately-held clinical-stage biotechnology company dedicated to developing varicella zoster virus (VZV) vaccines with improved tolerability and accessibility, today announced positive updated immunogenicity and safety data from its 876-patient Phase 2 trial of amezosvatein (a non-mRNA, adjuvanted subunit vaccine also known as CRV-101) head-to-head versus Shingrix® in participants aged 50 years and older.

At Day 421, one year after the second vaccine dose, anti-gE antibody levels for participants aged 50-69 randomized to receive the 100 μg gE antigen plus 15 μg SLA-SE adjuvant dose of amezosvatein remained non-inferior to Shingrix. Between Day 84 (one month after the second vaccine dose) and Day 421, anti-gE antibody geometric mean concentrations (GMC) declined for both amezosvatein (69.0%, n=49) and Shingrix (69.6%, n=184). In the 50-59 age group, the decline was 69.6% for both vaccines. For the 60-69 age group, the decline in anti-gE GMC antibodies was 68.4% for those receiving amezosvatein (n=25) and 69.7% for those receiving Shingrix (n=79).

Declines in anti-gE antibody levels in this time frame are expected and were similar in magnitude to those seen in Shingrix's Phase 3 trials, where Shingrix demonstrated vaccine efficacy of over 90% after three years and around 80% after 10 years. 1,2,3

In a post-hoc analysis after mean follow-up of 18.8 months in this Phase 2 trial, confirmed herpes zoster (shingles) cases were analyzed. Based on the shingles incidence rate from the placebo arm North American cohort of ZOSTER-006, a Phase 3 trial of Shingrix, 10 of the 876 participants in the Phase 2 trial should have been diagnosed with a confirmed shingles case absent effective vaccination.1

There were no confirmed shingles cases in the highest antigen dose (100 μg) arms studied for amezosvatein, including the 100/15 arm with Day 421 data reported above, and no confirmed shingles cases in the Shingrix arm. There was one confirmed case of shingles in the lowest antigen and adjuvant dose studied of amezosvatein (50 μg gE antigen plus 5 μg SLA-SE adjuvant). This 50/5 dose of amezosvatein used in Part A of the Phase 2 trial was previously determined to be immunologically inferior to Shingrix as measured by anti-gE antibody GMC and was discontinued for Part B.

“The Day 421 Phase 2 data continue to support our view amezosvatein has a comparable effect on the human immune system as Shingrix,” said Dr. Guy De La Rosa, Curevo's Chief Medical Officer.“Amezosvatein's non-inferior immunogenicity data and comparable herpes zoster case data, combined with amezosvatein's improved tolerability versus Shingrix in this Phase 2 trial we reported this time last year, provide us with great confidence and excitement to continue development of this vaccine.”

“Shingrix is the only premium-priced, large-population vaccine without current effective competition. This is in a market expected to be worth over $5 billion in 2025,” noted George Simeon, Curevo's Chief Executive Officer.“Past experience shows a comparable vaccine entering a market tends to split share with the incumbent vaccine. However, history also shows vaccines with better tolerability, like amezosvatein has demonstrated compared to Shingrix in our Phase 2 trial, can capture dominant market share.”

Additional Phase 2 trial data
The Phase 2 trial (NCT05304351) enrolled 876 participants to receive either amezosvatein or Shingrix on an identical two-dose, two months apart schedule. 876 participants were randomized to receive one of four different amezosvatein doses or Shingrix. The mean follow-up of the 619 participants receiving amezosvatein was 18.8 months. Mean follow-up of the 257 participants who received Shingrix was 21.5 months. The co-primary endpoints of the trial were anti-gE antibody humoral immune responses one month after the second vaccine dose (Day 84) and safety/reactogenicity. The randomized, observer-blind, and active-controlled trial was conducted at multiple centers in the USA. All suspected cases of shingles were confirmed by either PCR test or, if PCR testing was inconclusive or unavailable, by a blinded panel of shingles experts – a system similar to one used in multiple prior shingles vaccine pivotal studies. Day 421 measures were prospectively-defined secondary outcomes measures.

Vaccines are studied for both safety and reactogenicity/tolerability. Data on the reactogenicity/tolerability of amezosvatein and Shingrix were collected via a participant diary filled out for the seven days after each injection. Participants were asked to grade the tolerability of each vaccine on a scale of Grade 1 to Grade 3. Grade 1 represents what are considered normal reactions to an active vaccine that do not interfere or prevent daily activity. Grade 2 represents reactogenicity events interfering with daily activities. Grade 3 represents reactogenicity events preventing daily activities.

As previously reported, the 100/15 dose of amezosvatein demonstrated a clinically-meaningful and statistically-significant improvement for Grade 2 and Grade 3 reactogenicity versus Shingrix. Just 7.3% of participants in the trial receiving the highest dose of amezosvatein (n=55) reported a Grade 2 (interferes with daily activity) or Grade 3 (prevents daily activity) reactogenicity event compared to 33.3% of participants receiving Shingrix (n=225). Amezosvatein's advantage over Shingrix was statistically significant (p<0.001 in a post hoc analysis unadjusted for multiple comparisons) and consistent with both local and systemic reactions.

Serious adverse events (SAEs), potentially immune-mediated adverse events (PIMMCs), and medically-attended adverse events (MAAEs) were comparable at Day 421 between amezosvatein (n=166 across all doses studied) and Shingrix (n=225). All amezosvatein SAEs were "not related"; All Shingrix SAEs were“not related” or“unlikely related”. Amezosvatein had no PIMMCs reported. Shingrix had one PIMMC reported (polymyalgia rheumatica). All amezosvatein MAAEs were considered“not related” or“unlikely related”, except one event of non-shingles bilateral rash. One Shingrix participant reported four MAAEs as part of a constellation of symptoms considered“possibly related” (fatigue, myalgia, headache, migraine), and one additional Shingrix participant had presyncope (near fainting) considered“definitely related” with the investigator noting it was related to study procedure of blood collection. No deaths were reported in the amezosvatein arms. One unrelated death was reported in Shingrix arm (metastatic sarcoma & venous thrombosis).

About amezosvatein
'Amezosvatein' is the assigned non-proprietary name for CRV-101, a non-mRNA adjuvanted subunit vaccine under investigation by Curevo. Like Shingrix, amezosvatein uses a subunit protein antigen called glycoprotein 'E' (gE). Targeting the gE antigen is proven to elicit a long-term, protective immune response to prevent shingles. Also like Shingrix, amezosvatein uses an adjuvant targeting the TLR4 pathway to boost the immune response to the gE antigen. Amezosvatein was engineered to have a best-in-class safety profile in addition to manufacturing advantages to improve vaccine accessibility. The SLA-SE adjuvant formulation was developed at Seattle-based Access to Advanced Health Institute (AAHI) and amezosvatein was licensed from the Mogam Institute for Biomedical Research, a research institute funded by South Korea's GC Biopharma.

About shingles
Also called 'herpes zoster', shingles occurs when the varicella zoster virus causing childhood chickenpox re-emerges from sensory ganglion nervous system cells where the virus lies dormant after initial exposure. Virtually all adults have been exposed to the varicella zoster virus and around 30% will develop shingles at least once in their lifetime. The blistering skin rash accompanying shingles also causes severe pain, with both pain and rash lasting up to four weeks. Between 10-18% of those who get shingles develop post-herpetic neuralgia (PHN), a condition marked by debilitating nerve pain lasting over six months and often beyond one year. There is no approved treatment for PHN. Shingles may also affect the eyes, potentially causing loss of vision. Contracting shingles has also been linked with increased risk of heart attack, stroke, and dementia/Alzheimer's disease.

About Curevo
Curevo is a privately held, clinical-stage biotechnology company based near Seattle dedicated to reducing the burden of infectious disease by developing vaccines with improved tolerability and accessibility. Curevo's lead product is amezosvatein, a non-mRNA adjuvanted sub-unit vaccine to prevent shingles, a serious medical condition involving a painful, blistering skin rash where 10-18% of people also develop serious, long-lasting nerve pain. The current $5+ billion shingles vaccine market is characterized by accessibility issues and vaccine hesitancy/dose avoidance related to vaccine tolerability. Curevo is also developing a non-live, non-mRNA adjuvanted subunit chickenpox vaccine intended to reduce or eliminate barriers to immunizing immunocompromised children. For more information visit .

1. Lal, et al. New England Journal of Medicine, May 2015.
2. Boutry, et al. Clinical Infectious Disease, April 2022
3. Diez-Domingo J, et al. Abstract presented at European Society of Clinical Microbiology and Infectious Diseases (ESCMID); 27–30 April 2024, Barcelona, Spain.

Shingrix® is a registered trademark of GlaxoSmithKline, PLC.

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