Randomized Placebo-Controlled Study Provides Encouraging Results for a Higher Dose Formulation of Vaxchora® (CVD 103-HgR) as a Potential Tool in Containing Cholera Epidemics

REDWOOD CITY, Calif., Dec. 6, 2017 /PRNewswire/ -- PaxVax announced findings from a study published in the December 2017 issue of Clinical and Vaccine Immunology that shows the utility of a single high-dose CVD 103-HgR live oral cholera vaccine in developing country settings. The study was conducted in the West African country of Mali. Results support potential future development of a new formulation of Vaxchora^®—single high-dose CVD 103-HgR—as an important additional tool for global cholera control in developing countries.

"Immunization with a single-dose cholera vaccine that could rapidly protect people in developing countries who have not previously been exposed to cholera would be a significant asset in helping control outbreaks and lower mortality rates," said Myron M. Levine, M.D., D.T.P.H., Professor, Associate Dean for Global Health, Vaccinology & Infectious Diseases, Founder & Former Director, Center for Vaccine Development, University of Maryland School of Medicine and lead author in the Clinical and Vaccine Immunology study. "Given the highly encouraging results, we recommend that high-dose CVD 103-HgR is evaluated in developing countries as a matter of priority."

"The data published in Clinical and Vaccine Immunology is a first step in demonstrating the potential utility of a new formulation of Vaxchora (CVD 103-HgR) at a higher dose in endemic settings," said Nima Farzan, Chief Executive Officer and President of PaxVax. "In line with our social mission and our commitment to ensuring that our vaccines are available to at-risk populations, we are looking forward to engaging with partners and the global cholera community to undertake additional trials in cholera endemic areas further evaluating high dose CVD 103‑HgR."

Additional research will assess whether CVD 103-HgR is suitable in vaccination campaigns during outbreaks, for preemptive vaccination to diminish the burden of seasonal endemic cholera in developing country settings and for protection of high-risk populations, such as children.

About Cholera and Cholera Vaccines
Cholera, an intestinal infection transmitted by ingestion of food and water contaminated with Vibrio cholerae, presents a global public health challenge. It can cause fever, diarrhea, vomiting, painful cramping and dehydration. In severe cases, patients pass large amounts of diarrhea—up to one liter per hour—that causes rapid dehydration and can lead to death if left untreated. Cholera transmission is endemic in many areas of Africa, Asia and the Caribbean. There are an estimated three million cases of cholera worldwide every year. Outbreaks, such as the ones recently seen in Yemen, Bangladesh and Haiti, continue to have devastating effects on public health and can cause massive social disruption and high rates of deaths, especially in developing countries that lack infrastructure, modern sanitation and access to clean water.   

While there is a World Health Organization (WHO) stockpile of cholera vaccines for outbreak control, currently available vaccines are two dose regimens, administered two weeks apart. These vaccines have been useful in reducing seasonal increases in cholera rates in areas where this disease is endemic and where targeting of populations is possible, despite the logistical challenges of providing a second dose and the limitations of immune responses in young children.

About the Clinical and Vaccine Immunology Study

This Phase 2 clinical trial compared the vibriocidal responses of individuals in Mali (18 to 45 years old) who were randomized to ingest a single standard dose (10⁸ colony forming units [cfu]) or a high dose (10⁹ cfu) of CVD 103-HgR with buffer or two doses of an inactivated cholera vaccine that is currently WHO prequalified. For blinding, CVD 103-HgR recipients received a placebo two weeks before or after ingesting the study vaccine. The primary outcomes were seroconversion—a correlate of protection—between the baseline and 14 days after CVD 103-HgR ingestion and following the first and second doses of inactivated cholera vaccine.

By study day 14, the rate of seroconversion after ingestion of a single high dose of CVD 103-HgR was 83.3% vs. 71.7% for a standard dose of CVD 103-HgR, which is the dose that is currently approved in the U.S. for use in travelers and 56.0% for a single dose of the inactivated vaccine. 

By study day 28 (14 days following the second dose of the inactivated cholera vaccine), the rate of seroconversion was 89.4% for a single high dose of CVD 103-HgR vs. 83.7% and 76.1% for a standard dose of CVD 103-HgR and for the second dose of the inactivated vaccine, respectively.  

All formulations evaluated in this study were well tolerated.

About the CVD 103-HgR formulation

CVD 103-HgR was originally licensed and commercialized under the name Orochol^® by the Swiss Serum and Vaccine Institute for protection of travelers from industrialized countries, and a higher dose "endemic" formulation was used in developing countries (Orochol E^®). In 2010, PaxVax acquired rights to CVD 103-HgR, re-developed the vaccine under the trade name Vaxchora, conducted clinical studies, received Food and Drug Administration (FDA) approval and is commercializing Vaxchora for use in U.S. travelers to cholera-affected areas.

About Vaxchora (Cholera Vaccine, Live, Oral)

Vaxchora is an oral vaccine indicated for active immunization against disease caused by Vibrio cholerae serogroup O1. It was approved by the FDA in June 2016 as the only vaccine available in the U.S. for active immunization against cholera. In May 2017, the U.S. Centers for Disease Control and Prevention (CDC) published the recommendation stating that Vaxchora should be used in adults traveling to an area of active cholera transmission.

The approval of Vaxchora was based on positive results from a 10-and 90-day cholera challenge trial that demonstrated vaccine efficacy of 90.3% at 10 days and 79.5% at three months post-vaccination, as well as two safety and immunogenicity trials in healthy adults. Vaxchora is approved for use in adults 18 through 64 years of age traveling to cholera-affected areas. The effectiveness of Vaxchora has not been established in persons living in cholera-affected areas or in persons who have pre-existing immunity due to previous exposure to Vibrio cholerae or receipt of a cholera vaccine. Vaxchora has not been shown to protect against disease caused by Vibrio cholerae serogroup O139 or other non-O1 serogroups.

Vaxchora is contraindicated in people with a history of severe allergic reaction (e.g., anaphylaxis) to any ingredient of Vaxchora or to a previous dose of any cholera vaccine. The safety and effectiveness of Vaxchora have not been established in immunocompromised persons. Vaxchora may be shed in the stool of recipients for at least seven days. There is a potential for transmission of the vaccine strain to non-vaccinated close contacts (e.g., household contacts). Use caution when considering whether to administer Vaxchora to individuals with immunocompromised close contacts. The most common adverse reactions (incidence >3%) were: tiredness (31%), headache (29%), abdominal pain (19%), nausea/vomiting (18%), lack of appetite (17%) and diarrhea (4%).

For the full Prescribing Information, please visit www.vaxchora.com.

About PaxVax

PaxVax is a leading independent vaccine company that is devoted to bringing specialty vaccines that protect against overlooked infectious diseases to market, providing effective tools for health care providers who serve the 100 million people per year who travel to countries where these diseases are present. It commercializes vaccines for typhoid fever (Vivotif^®) and cholera (Vaxchora^®), and has a robust pipeline with vaccines at various stages of preclinical and clinical development for adenovirus, chikungunya, hepatitis A, HIV and Zika. As part of its social mission, PaxVax is also committed to making its vaccines available for use in developing world and increasing access to vaccines for the people who need them most. More information is available at http://www.paxvax.com/.

SOURCE PaxVax

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