Spero Therapeutics, LLC, a biopharmaceutical company founded to develop novel therapies to treat bacterial infections, announced today that it has completed a $51.7 million Series C preferred financing led by new investor GV (formerly Google Ventures). The round includes participation by additional new investors RA Capital Management and Rock Springs Capital as well as existing investors.

Proceeds from the financing will be used to advance Spero's unique pipeline of antibacterials focused on drug-resistant bacterial infections. Specifically, the additional funding will enable Spero to move additional pipeline programs such as SPR994 into the clinic and advance its Potentiator program into later stage clinical trials.

'We are grateful for the continued strong support from our existing investors as we welcome new partners who share our vision for building a multi-program approach to the major unmet need in drug-resistant bacterial infections,' said Ankit Mahadevia, M.D., President and Chief Executive Officer of Spero. 'The financing provides us the necessary resources to execute our aggressive strategy to address this growing threat of multidrug-resistant bacteria, and we are proud to have earned the confidence of such well-respected partners in our efforts.'

'Spero is working on one of the greatest unmet needs in medicine - developing antibacterial treatments for some of the most resistant infections patients today,' said GV General Partner Krishna Yeshwant. 'The company has assembled a team with the proven ability to bring new antibacterials to the market, and has made remarkable progress in building a differentiated pipeline in a short period of time.'

The round included participation from existing investors including Atlas Venture, S.R. One, Limited, MRL Ventures Fund, Lundbeckfonden Ventures, The Kraft Group and Osage University Partners.

About Spero

Spero Therapeutics is a global multi-asset clinical-stage biopharmaceutical company headquartered in Cambridge, Massachusetts dedicated to developing a novel and highly differentiated pipeline of antibacterials focused on unmet needs of patients with drug resistant bacterial infections. Spero Therapeutics is advancing two lead programs in parallel, SPR741 and SPR994. SPR741, also called Potentiator, is a platform approach to combination therapy to treat serious and life-threatening multi-drug resistant gram negative infections, such as Enterobacteriaceae and Acinetobacter baumanii, including carbapenem resistant strains. SPR741 increases the spectrum and potency of more than two dozen classes of gram positive antibiotics to include activity against multidrug resistant gram negative infections when used in combination. SPR994 is a novel oral agent that has demonstrated potent in-vitro activity against a wide variety of gram-negative bacteria, including extended spectrum beta lactamases (ESBLs), and gram-positive bacteria. Spero Therapeutics also has a robust preclinical pipeline including SPR720, which is a preclinical oral asset for nontuberculous mycobacteria (NTM) lung disease, a rare and often chronic fatal infection. In addition, Spero Therapeutics has a variety of other discovery antimicrobials focused on drug-resistant infections.