Arsanis, Inc., a clinical-stage biopharmaceutical company developing targeted monoclonal antibodies (mAbs) for pre-emptive and post-infection treatment of serious infectious diseases, today announced the closing of a $45.5 million Series D financing led by the Bill & Melinda Gates Foundation. Several additional new investors participated in the financing, including GV (formerly Google Ventures) and Alexandria Venture Investments. The company's existing investors, including OrbiMed, Polaris Venture Partners, SV Health Investors, NeoMed, EMBL Ventures and the Anna Maria and Stephen Kellen Foundation also participated in the Series D round.

"The caliber of investors attracted to Arsanis underscores the importance of the work we are doing to develop targeted monoclonal antibody therapies to prevent and treat serious infectious diseases and mitigate the growing global health threat of antimicrobial resistance," said Rene Russo, Pharm.D., BCPS, chief executive officer, Arsanis. "This financing allows us to focus our efforts on completing the ongoing Phase 2 study for ASN100, a potential new standard of care for the prevention of Staphylococcus aureus pneumonia in high-risk mechanically ventilated patients. We also plan to continue to advance our preclinical gram-negative programs, as well as our respiratory syncytial virus program, toward the clinic."

S. aureus pneumonia in mechanically ventilated patients is a life-threatening infection, with an overall mortality rate of approximately 30% despite antibiotic treatment.1 Arsanis' lead program, ASN100, is a combination of two human monoclonal antibodies, ASN-1 and ASN-2, that uniquely disarms S. aureus without propagating antibiotic resistance by broadly neutralizing the six cytotoxins implicated in the pathogenesis of pneumonia. ASN100 has received Fast Track designation from the U.S. Food and Drug Administration (FDA), and a global Phase 2 study is underway to evaluate the safety and efficacy of a single dose of ASN100 versus placebo for the prevention of S. aureus pneumonia in high-risk, mechanically ventilated patients. Data from the Phase 2 study are anticipated in 2018.

In addition to its ASN100 program for S. aureus, Arsanis is advancing its deep pipeline of mAbs targeting serious bacterial and viral infections including multi-drug resistant Escherichia coli and Klebsiella pneumoniae, Streptococcus pneumoniae, and RSV.

"Arsanis is poised to make a significant mark on the way serious infections are prevented and treated, particularly in light of the challenges faced globally as more infectious diseases are resistant to available treatments," said Carl L. Gordon, Ph.D., CFA, founding partner and co-head of global private equity, OrbiMed. "The Arsanis leadership team has the deep expertise needed to succeed, and we are proud to partner with our new investors to support the company's efforts as it advances promising monoclonal antibodies through clinical development for S. aureus pneumonia and other life-threatening infections."

The equity investment by the Gates Foundation was made as part of its program-related investments (PRI) strategy, which aims to support innovation, encourage market-driven efficiencies, and attract external capital to promising global health and development projects that improve the lives of the world's most vulnerable people. This closing provides the opportunity for Arsanis to conduct defined discovery research in neonatal S. aureus sepsis, an infection that disproportionately affects newborns in developing countries, with the potential for future funding to advance a neonatal sepsis candidate. In addition, the foundation has the option to provide further funding to Arsanis for up to two additional discovery programs to support its global health strategy.

About Arsanis, Inc.
Arsanis is a clinical-stage biotechnology company leading the development of targeted monoclonal antibodies (mAbs) for pre-emptive therapy and treatment of serious infectious diseases. The company's current programs address pathogenic processes selectively, rather than aiming to broadly eliminate pathogens, potentially allowing Arsanis to address critical infections without contributing to the problem of antimicrobial resistance. The company is building a broad product pipeline addressing the most important infectious diseases that threaten patients globally. Its lead clinical program, ASN100, is being evaluated in a Phase 2 clinical study for the prevention of Staphylococcus aureus pneumonia in high-risk patients.