Serum Institute’s meningitis ACWXY vaccine candidate demonstrates strong safety and immunogenicity

June 4, 2021 by PATH

Results from a Phase 2 clinical study of a pentavalent meningococcal meningitis vaccine designed for use in the African meningitis belt demonstrate the vaccine candidate to be safe, well-tolerated, and capable of producing strong immune responses to all five serogroups.

Meningococcal meningitis, a type of bacterial meningitis, is one of the most feared diseases in Africa—responsible for deadly annual outbreaks and epidemics that have led to tens of thousands of cases and thousands of deaths each year. The vaccine candidate (NmCV-5), manufactured by the Serum Institute of India, Pvt. Ltd. (SIIPL), is a conjugate vaccine designed to protect against meningococcal serogroups A, C, W, X, and Y. Detailed results were published in the New England Journal of Medicine.

Existing polyvalent meningococcal conjugate vaccines are often cost prohibitive for people living in countries with low- and middle-income economies. SIIPL’s vaccine is designed to be affordable for low-resource nations, which suffer the greatest disease burden and are where people are most likely to experience severe outcomes. Moreover, no vaccines are licensed to protect against serogroup X, which in recent years has increased in prevalence in the meningitis belt.

With funding from the UK’s Foreign, Commonwealth and Development Office, PATH is supporting development of NmCV-5 and, along with SIIPL, co-sponsored the Phase 2 clinical study that took place between November 2017 and August 2018 in Bamako, Mali. A total of 376 healthy children 12-16 months of age participated in the study and received two doses of NmCV-5 with adjuvant, NmCV-5 without adjuvant, or a licensed quadrivalent meningococcal comparator vaccine. Analysis showed that a single dose of NmCV-5 elicited immune responses comparable to or superior to two doses of the comparator vaccine, Menactra®, and that the addition of an adjuvant provided no benefit.

These promising results demonstrate the vaccine’s potential to one day eliminate meningococcal meningitis epidemics from Africa and support the ongoing Phase 3 clinical development of NmCV-5.

Meningococcal meningitis can occur anywhere but is most prevalent in Africa’s meningitis belt, a string of 26 countries stretching from Senegal and The Gambia in the west to Ethiopia in the east with an at-risk population of 450 million. Every year, people living in these countries face the threat of meningitis epidemics during the dry season from January to June. The recurring epidemics place enormous burdens on local health systems and inflict damage that remains long after the disease passes. Even with timely antibiotic treatment, one in ten infected people will die within days of the onset of symptoms; without treatment, 50 percent of those infected die.

Until recently, serogroup A meningococcus was responsible for more than 80 percent of Africa’s meningitis epidemics. But the 2010 introduction of MenAfriVac®, a conjugate vaccine tailor-made for Africa that protects against meningitis A, has eliminated the circulation of serogroup A meningitis wherever the vaccine has been used. MenAfriVac was developed through the Meningitis Vaccine Project, a collaboration between PATH and the World Health Organization (WHO) to put a stop to meningitis epidemics in Africa. SIIPL was a key partner in that effort, willing to manufacture the vaccine at a price set by African nations, to ensure access and impact. MenAfriVac® has so far been introduced in 24 of 26 meningitis belt countries and delivered to more than 340 million people.

NmCV-5 extends SIIPL’s and PATH’s commitment to make vaccines available for the people who need them most, at a price they can afford. NmCV-5 is currently undergoing Phase 3 clinical study in healthy children and adults in Bamako, Mali, and Banjul, The Gambia. That study is designed to lead to licensure and WHO prequalification and results are expected later in 2021. In parallel, SIIPL is conducting a Phase 2/3 clinical study in adults in India.

Efforts to develop NmCV-5 align with WHO’s Defeating Meningitis by 2030 initiative, which aims to overcome bacterial meningitis as a public health threat and lays out a roadmap for how to do so. Reducing cases and deaths from vaccine-preventable bacterial meningitis is a critical component of that strategy, and uptake of multivalent meningococcal vaccines is identified as a landmark achievement. The partnership between PATH and SIIPL is essential for increasing tools in the global meningococcal meningitis prevention toolbox.