Chimerix (Nasdaq: CMRX), which has a contract potentially worth more than $400 million in the development of a first vaccine targeting smallpox, reports progress in development of an antiviral. In recent tests, its brincidofovir successfully treated 100 percent of animals infected with rabbitpox.

The test results were disclosed Monday at a biodefense and emerging disease meeting in Virginia.

“100 Percent Survival Demonstrated in Animals Treated Immediately With Brincidofovir at Time of Confirmed Infection,” Chimerix declared in a press release.

“These effects in the brincidofovir-treated animals may decrease the spread of infection between animals, and if confirmed in humans, brincidofovir may decrease person-to-person transmission of smallpox in a bioterror event,” the company explained.

Animals treated immediately once fever was detected showed the greatest impact.

The tested animals were administered what the company called a “la lethal inoculum of rabbitpox virus and monitored for clinical signs of disease.”

Chimerix CEO Michelle Berrey called the test a “pivotal animal model study.”

“Data from this pivotal animal model study support the potential to advance brincidofovir as a medical countermeasure for smallpox,” she said in a statement.

“There is currently no antiviral approved to treat smallpox, considered a Category A Priority Pathogen by the National Institute of Allergy and Infectious Diseases (NIAID). We look forward to working closely with the FDA and BARDA to contribute to the U.S. national security and public health preparedness.”

Chimerix has been working with the Biomedical Advanced Research and Development Authority, or BARDA, since 2011. Last Septemberf, it received a 15-month extension on that contract.

Brincidofovir, the lead product for Chimerix, has shown in vitro antiviral activity against all five families of DNA viruses that affect humans, including the herpesviruses and adenoviruses and has received “fast track” development status from the FDA for cytomegalovirus (CMV), adenovirus, and smallpox.

About Smallpox

Smallpox is estimated to have killed more than one billion people worldwide prior to its eradication in 1980 following a global vaccination campaign. Smallpox stocks remain for research purposes in the United States and Russia; however, undeclared stocks are suspected to exist.

from Chiemrix

In discussing the study, Chimerix noted how infected animals survived vs. those who received a placebo and added that immediate treatment proved to be the most effective.

“At the time of detection of fever, a clinical indication of confirmed infection, animals were randomized to receive placebo or brincidofovir administered immediately or after a 24, 48, or 72 hour delay.

“Animals that received brincidofovir immediately had 100 percent survival, and animals that received brincidofovir after a 24 or 48 hour delay had a 93 percent survival, statistically significant improvements compared with less than 50 percent survival in animals that received placebo.

“Treatment with brincidofovir begun immediately or following a 24 or 48 hour delay resulted in an immune response and a reduction in the amount of virus in the blood.

“These effects in the brincidofovir-treated animals may decrease the spread of infection between animals, and if confirmed in humans, brincidofovir may decrease person-to-person transmission of smallpox in a bioterror event.”

​Chimerix said the tests were “conducted under the Food and Drug Administration’s (FDA) Animal Efficacy Rule, which allows for testing of investigational drugs in animal models to support effectiveness in diseases which are not ethical or feasible to study in humans. In this well-characterized model of smallpox, animals were administered a lethal inoculum of rabbitpox virus and monitored for clinical signs of disease.”