US-based biopharmaceutical company Emergent BioSolutions has completed the acquisition of exclusive global rights to Tembexa (brincidofovir) from Chimerix.

Tembexa is an oral antiviral approved by the US Food and Drug Administration (FDA) for the treatment of smallpox disease in adults and paediatric patients, including neonates.

The FDA approval was based on efficacy data in two lethal orthopoxvirus animal models of human smallpox disease, and the drug’s effectiveness has not been determined in humans.

The drug comes with a Boxed Warning for increased risk for mortality when used for a longer duration.

In May this year, Emergent signed an agreement to acquire Tembexa.

Under the terms of the deal, Emergent was expected to make a $238m upfront payment and up to $124m based on the potential exercise of procurement options by the US government.

Chimerix would receive additional payments of up to $12.5m, subject to the achievement of certain development-based milestones.

The closing of the acquisition is subject to satisfaction of all closing conditions, including the expiration of the waiting period under the Hart-Scott-Rodino Act.

Also, it is subject to consent from the Biomedical Advanced Research and Development Authority (BARDA), for a sub-contract agreement between Chimerix and Emergent.

Emergent MCM business SVP Paul Williams said: “The addition of TEMBEXA to our smallpox medical countermeasure franchise, which consists of our smallpox vaccine and therapeutic for smallpox vaccine complications, creates a more comprehensive offering to combat this deadly public health threat.

“We look forward to supporting the U.S. government’s smallpox preparedness strategy on a broader scale by executing on this BARDA contract.”

In August this year, Chimerix has been awarded a 10-year contract, worth up to $680m, to supply up to 1.7 million courses of Tembexa tablets and suspension to the US government.

The contract includes an initial product procurement valued at around $115m, with an option to procure worth up to $551m in future, at the sole discretion of BARDA.

In addition, the contract includes reimbursed post-marketing activities worth $12m.