Lead Program: Best-in-Class Pneumococcal Conjugate Vaccine

Background

Our lead broad-spectrum pneumococcal conjugate vaccine (PCV) is designed to provide expanded protection against circulating strains of pneumococcus beyond the coverage provided by the current vaccines used in infants and adults. SutroVax has generated pre-clinical proof-of-concept with its broad-spectrum PCV in head-to-head studies against current vaccines and has advanced the program into IND-enabling development to subsequently demonstrate proof-of-concept in adults and children.

The Problem

Pneumococcal disease is an infection caused by Streptococcus pneumonia that leads to a wide range of serious illnesses including pneumonia, meningitis and blood stream infection as well as ear and sinus infections. According to the Centers for Disease Control and Prevention (CDC), an estimated 900,000 Americans get pneumococcal pneumonia each year and up to 400,000 hospitalizations occur in the US. In addition, about 18,000 older adults die each year from pneumococcal disease in the U.S. The market-leading vaccine against pneumococcal disease is Prevnar 13®, a conjugate vaccine consisting of 13 pneumococcus-derived polysaccharide antigens conjugated to a carrier protein. The carrier protein confers T-cell help eliciting memory responses leading to long-lasting protection against the thirteen covered serotypes. Prevnar has been a major commercial success and has worldwide sales of over $6 billion annually yet does not protect against a significant number of circulating pneumococcal strains that cause invasive disease in adults and children.

Limitations of traditional conjugate vaccine chemistry have impeded efforts to expand coverage of existing vaccines due to carrier-induced suppression. Conventional conjugation technologies result in indiscriminate conjugation of antigens to the protein carrier limiting their ability to consistently confer T-cell help. Addition of incremental strains further weakens the immune response by increasing carrier protein burden and diverting the host-immune response to the non-disease specific carrier and away from the disease-specific antigen resulting in a less-efficacious vaccine.

Our Solution

SutroVax conjugate vaccines are developed using the Xpress CF Platform, which enables precise conjugation of pneumococcus-derived polysaccharides onto carrier proteins via the incorporation of non-native amino acids (nnAA) as conjugation anchors. Due to the exquisite fidelity of the technology, nnAAs are introduced at site-specific locations on a protein carrier avoiding T-cell epitopes thereby resulting in higher-potency conjugates. By employing more potent conjugates, SutroVax uses less protein carrier in its broad-spectrum PCV to avoid carrier-induced suppression despite expanding coverage beyond the 13-valent PCV available today.

SutroVax has generated pre-clinical proof-of-concept in head-to-head studies with its broad-spectrum PCV compared to current vaccines using well accepted immunological endpoints, including antibody responses (IgG) and functional responses (opsonophagocytic activity).