Two Maryland pharmaceutical companies — PharmAthene, an Annapolis-based immunotherapeutics firm, and Altimmune, a Gaithersburg-based private biodefense therapeutics firm –announced a merger to form a company targeting infectious diseases, including influenza and hepatitis B.

The two companies’ boards signed a definitive agreement to an all-stock merger Thursday morning.

Altimmune will become a wholly-owned subsidiary of PharmAthene focusing on four clinical stage products and one preclinical stage product.

The new company, headquartered in Gaithersburg, Maryland, will operate under the name Altimmune and trade on the NYSE under the ticker symbol ALT.

Altimmune was previously a private company. Altimmune’s original shareholders will own 58.2 percent of the new company.

Together, the new firm will have $20 million in cash and commitments.

“A merger with Altimmune is an ideal strategic match. It fulfills our stated goal of continuing to build value for PharmAthene shareholders after we distribute the SIGA litigation proceeds on Feb. 3,” John M. Gill, chief executive officer of PharmAthene said in a news release. “By combining forces, we will diversify our portfolio into attractive commercial product opportunities and leverage our capabilities for developing next generation anthrax vaccines.”

Altimmune’s Chief Executive Officer Bill Enright and Chief Financial Officer and Executive Vice President of Corporate Development Elizabeth Czerepak will retain their respective positions. The new board of directors will be comprised of three PharmAthene and four Altimmune directors.

The boards for both companies unanimously approved the terms of the agreement. The deal is subject to approval from both company’s shareholders.

Altimmune’s investors include Novartis Venture Fund, HealthCap, Truffle Capital and Redmont Capital.

Altimmune’s clinical stage products:

• NasoVax: An intranasal flu vaccine set to begin Phase 2 study in mid-2017.
• HepTcell: A therapeutic and potential cure for chronic hepatitis B. The drug is currently in Phase 1 with data expected by the end of 2017.
• SparVax-L: A highly-stable, NIAID-funded anthrax vaccine with a long shelf life. A Phase 2 study is expected in the second half of 2017.
• NasoShield: A single-dose anthrax vaccine taken intranasally. A Phase 1 trial is expected during the second half of 2017.

Altimmune’s preclinical product:

• Oncosyn: Investigating uses for Altimmune’s proprietary synthetic peptide technology

The 8-K detailing the terms of the merger can be read here.