Rib-X Pharmaceuticals, Inc. announced the receipt of a $9 million milestone payment from Sanofi. The payment follows the recent signing of a worldwide research collaboration and option for license with Sanofi for novel classes of antibiotics resulting from Rib-X's RX-04 programme for the treatment of drug resistant Gram-negative and Gram-positive pathogens. The payment, which was part of the pre-specified terms of the agreement, was for the achievement of several undisclosed research-based milestones.

"The receipt of this milestone payment from Sanofi on the heels of signing our worldwide collaboration agreement is representative of the rapid progress we have made in advancing the RX-04 programme toward the clinic," said Mark Leuchtenberger, president and chief executive officer at Rib-X Pharmaceuticals. "We look forward to working in partnership with Sanofi to continue advancing these treatments toward the clinic and eventually to bring them to patients as commercialized products."

Under the terms of the agreement announced on July 6, 2011, Rib-X received $10 million in an upfront payment and has now received an additional $9 million in near-term research-based milestones. Rib-X will be eligible to receive further payments for the achievement of research, preclinical, regulatory and commercial milestones. Sanofi has the right to develop multiple products under this agreement. Except for those assets licensed to Sanofi through the agreement, Rib-X retains its rights to the discovery platform and its future programmes. The agreement could result in up to $86 million in development and regulatory milestones on a per product basis. Commercial milestones could exceed $100 million on a per product basis. Rib-X retains a co-promotion option in the United States on one of the molecules coming from the collaboration. Royalty rates on net sales could reach low double digit figures.

Rib-X’s RX-04 programme employs a proprietary approach for rational drug design resulting in entirely new families of compounds that have demonstrated efficacy at low, single doses in murine infection models. The RX-04 development programme has shown antibacterial activity against a number of the most difficult to treat, clinically important, multi-drug resistant Gram-negative and Gram-positive pathogens, including NDM-1-producing Enterobacteriaceae, P. aeruginosa and A. baumannii and MRSA. The Rib-X RX-04 programme targets bacterial ribosomes, an internal cell component, where proteins are synthesized from amino acids and RNA. Recently presented data confirms the novel classes directly impact ribosome function and exert their antibacterial activity by interfering with protein synthesis.

Multi-drug resistant bacteria are an increasing public health crisis. According to the Centers for Disease Control, infections caused by such bacteria result in longer and more expensive hospital stays and may lead to death. According to the Infectious Disease Society of America (IDSA), hospital-acquired infections result in nearly 100,000 deaths per year in the United States, the vast majority of which are due to antibiotic-resistant pathogens. Based on studies of the costs of infections caused by antibiotic-resistant pathogens versus antibiotic-susceptible pathogens, IDSA estimates that the annual cost to the US health care system of antibiotic-resistant infections is $21 billion to $34 billion and more than eight million additional hospital days. Bacteria come in two major classes, defined by their appearance when stained to make them visible under a microscope: Gram-positive, which appear as violet blue typically lack the outer membrane found in Gram-negative bacteria, which appear pink after staining.

Rib-X Pharmaceuticals is developing broad spectrum antibiotics with superior coverage, safety and convenience to deliver new standards of care for patients with serious infections.