Biota Pharmaceuticals said today it has sold its broad spectrum antibiotic program to a new subsidiary of Spero Therapeutics for an undisclosed price.

The deal will expand Spero’s pipeline of candidates for bacterial infections, while reflecting Biota’s decision to concentrate on developing mid-stage antiviral candidates for infections that affect significant numbers of patients globally.

“This transaction gives us the opportunity to economically benefit from the antibiotic assets in our infectious disease portfolio and to fully focus our resources on our clinical-stage direct antiviral programs aimed at addressing infections with limited therapeutic options,” Biota President and CEO Joseph Patti, Ph.D., said in a statement.

Biota’s clinical pipeline includes vapendavir, an oral treatment for human rhinovirus infections in moderate-to-severe asthmatics, now under study in the ongoing Phase IIb SPIRITUS trial; BTA585, a Phase II oral fusion protein inhibitor indicated for treatment and prevention of respiratory syncytial virus infections; and BTA074, a Phase II topical antiviral treatment for condyloma caused by human papillomavirus types 6 and 11.

BTA074, formerly AP611074, was the lead product of Anaconda Pharma before Biota acquired Anaconda last year for up to $38 million.

Headquartered in Cambridge, MA, Spero has three bacteria-fighting programs in development. One applies the company’s Potentiator therapeutic platform, designed to develop new chemical entities or “potentiators” that interact with the outer membrane of Gram-negative bacteria to increase the membrane’s permeability, thus allowing Gram-positive antibiotics to enter and kill the cell. Spero reasons that using existing drugs will prove more effective than creating a new antibiotic to which bacteria can quickly adapt.

Spero’s multiple virulence factor Regulator (MvfR) program is designed to explore the possibility of blunting the virulence of bacteria, essentially “buying time” so that antibiotics can take effect. The company is also developing its dihydrofolate reductase (DHFR) program, which seeks to expand the antibacterial spectrum of a novel antifolate to treat trimethoprim resistance isolates, including key Gram-negative pathogens.

“As we look to advance our programs into the clinic, these assets from Biota will support our mission of finding innovative treatments for serious bacterial infections,” added Spero co-founder and CEO Ankit Mahadevia, M.D.

The deal with Biota is Spero’s second expansion of its anti-infective pipeline this year. In January, Spero agreed to license from Promiliad Biopharma its DHFR inhibitors, designed to target Gram-positive and -negative bacteria, fungi, and protists, for an undisclosed price.

A month later, Spero announced that its investors from its series A financing round had agreed to provide $30 million in preferred series B financing to pay for development of the Potentiator platform and DHFR program. Those investors are Atlas Venture, SR One, MRL Ventures, Lundbeckfond Ventures, The Kraft Group, and Partners Innovation Fund.

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