We believe that our proprietary chemistry technology, licensed from Harvard on an exclusive worldwide basis and enhanced at Tetraphase, represents a significant innovation in the creation of tetracycline drugs and has the potential to reinvigorate the clinical and market potential of the class.
The tetracycline class of antibiotics has been used successfully for more than 50 years. Unlike our tetracycline compounds, all tetracyclines on the market and under development of which we are aware are produced semi-synthetically, first in bacteria and then modified in a limited number of ways by available chemistry. These conventional methods have only been able to produce tetracycline antibiotics with limited chemical diversity, making it difficult for conventional technology to create tetracycline antibiotics that address a wide variety of multi-drug resistant bacteria. In part, because of the challenges in creating novel tetracycline molecules, only one tetracycline antibiotic has been developed and approved by the FDA for sale in the United States in the past 30 years.
By contrast, our proprietary technology makes it possible to create novel tetracycline antibiotics using a practical, fully synthetic process for what we believe is the first time. This fully synthetic process avoids the limitations of bacterially derived tetracyclines and allows us to chemically modify many positions in the tetracycline scaffold, including most of the positions that we believe could not practically be modified by any previous method. Using our proprietary chemistry technology, we can create a wider variety of tetracycline-based compounds than was previously possible, enabling us to pursue novel tetracycline derivatives for the treatment of multi-drug resistant bacteria that are resistant to existing tetracyclines and other classes of antibiotic products.
The diagram below illustrates the tetracycline core scaffold. Scaffold positions marked with dots have been modified to date using conventional chemistry to create either tetracycline drugs that have been marketed or drug candidates of which we are aware that are currently in development. Our fully synthetic process also allows for modification of the positions marked with dots, but with greater opportunity for substitution than is possible using conventional chemistry. The scaffold positions marked with stars in the diagram below indicate useful positions that we have modified through our fully synthetic process that could not practically be modified by conventional chemistry.
While the four positions on the bottom of the scaffold in the diagram above that are not marked with dots or stars can also be modified using our proprietary chemistry technology, these positions are involved in the binding of tetracyclines to the bacterial ribosome and, consequently, changes to these positions greatly reduce antibacterial activity of compounds. As a result, we are not pursuing compounds based on modifications of these positions.
We believe that our approach to tetracycline drug development provides us with strong intellectual property protection. We hold or have licensed rights under patents and patent applications that protect both our synthetic processes for developing tetracyclines and the compositions of matter of the individual compounds themselves. These include patents and patent applications directed towards the composition of matter for key intermediates like the one used in the synthesis of eravacycline and our other product candidates. Unless a new synthetic method is created, we believe that, for the life of our intellectual property, our proprietary chemistry technology will be the only practical way of modifying the positions on the tetracycline core scaffold that have not been previously modified using conventional chemistry.
Our proprietary chemistry technology has allowed us to develop compounds that have been highly active in in vitro studies against tetracycline-resistant bacterial strains, including multi-drug resistant Gram-negative bacteria, and that have novel pharmacokinetic properties. To date, we have used our proprietary chemistry technology to create more than 2,800 new tetracycline derivatives that we believe could not be practically created with conventional methods. Our discovery program is focused on identifying novel compounds that will be effective against the toughest multi-drug resistant Gram-negative bacteria.