SIGA awarded contract from U.S. Department of Defense to expand use of smallpox drug

The U.S. Department of Defense (DoD) has awarded SIGA Technologies a contract valued at up to $19.5 million, with an initial award of $12.4 million, to advance work that could provide aexpansion for TPOXX, a drug used to treat smallpox.

This multi-year contract, which was announced this month, would include research into the drug’s application for Post-Exposure Prophylaxis (PEP) of the disease.

The funding will also support manufacturing material for clinical trials and the preparation for a human clinical safety study. The study would potentially require dosing for 28 days, mimicking the timeline of a smallpox outbreak. SIGA is already working with the U.S. Army Medical Research Institute of Infectious Disease on animal studies to evaluate the efficacy of TPOXX as a potential PEP therapy for smallpox.

“We’re very pleased to be working with the JPEO (Joint Program Executive Office) at the Department of Defense on this important potential label expansion,” said SIGA CEO Phil Gomez. “TPOXX was supported early on by DTRA (Defense Threat Reduction Agency) and the Department of Defense has been involved in the program for many years. They’ve been a great partner.”

The goal of SIGA’s PEP research is to treat people well before the onset of symptoms of smallpox. Symptoms caused by the variola virus, which results in the smallpox disease, can arise 14 days post-infection. There is no diagnostic test to determine whether an individual has been infected before symptoms occur. During this two-week period, an infected person is highly contagious.

TPOXX, a small-molecule antiviral, is stockpiled by the U.S. government. In the event of a smallpox outbreak, public health officials can only treat people affected with an active outbreak or those in the vicinity of someone who had exposure to the virus. Without a diagnostic test, health workers are making their best guesses about who to treat and when. If a vaccine is given more than approximately four days after infection, it’s not effective. SIGA officials say the best treatment available may be to administer the vaccine in combination with TPOXX.

Smallpox vaccination campaigns ended in the United States in the 1970s and the disease was eradicated globally by 1980. Anyone born post that period is vulnerable to the disease, and those immunized long ago may be vulnerable as immunity can be lost over time. Of additional concern are the small amounts of the variola virus that exist in research labs in the United States and Russia, raising concerns about access to the virus and whether it could be used a bioweapon.

Last year a research team at the University of Alberta published in the journal PLOS outlining how they assembled horsepox, a cousin to smallpox, from pieces of DNA received by mail. The publication of these results faced international criticism by scientists because it showed anyone with an internet connection how to replicate the procedure. The concern was that this knowledge could be applied to the development of smallpox.

“There’s certainly a consistent awareness of it,” Gomez said of the horsepox synthesis. “And that’s why the government is focusing on these issues and stockpiling TPOXX.”