Therapy Analysis - Chlamydia, Gonorrhoea & Syphilis
Preventative therapies
Preventative or prophylactic therapies exist as an alternative approach for tackling bacterial STIs, and fall into 3 categories: vaccines, chemical barriers and physical barriers.
The lack of R&D for new agents against bacterial STIs reflects a wider malaise in antibiotic/antibacterial development, an area which has delivered only 2 novel chemical entities in the past 10 years. There are signs, however, that some companies are showing renewed interest in this area, which has been perceived to offer insufficient ROI to be worth investing in. It is to be hoped that the growing threat of bacterial resistance will increasingly persuade companies of the merits in investing in this area of development.
With the recent approval of Gardasil, the groundbreaking vaccine against the viral STI Human papilloma virus (HPV), it is no surprise that vaccines are being considered for the prevention of STI's. In fact, our data shows that this has been a common approach to chlamydia and gonorrhoea prophylaxis (Graph 2). However, possibly owing to the complexity of vaccine development, only one of these products is currently in active development. Emergent BioSolutions is currently developing a recombinant protein subunit chlamydia vaccine, for use in sexually-active individuals aged 15- 24 years. Now in preclinical development, it has displayed promising results in protecting mice against both lower reproductive tract infection, and infertility caused by C. trachomatis. With Gardasil potentially revolutionizing thinking on the prophylaxis of STIs , it is hoped that there will be development of a chlamydia or gonorrhoea vaccine of the same worth.
As an alternative, topically-applied prophylactic agents are also under development. Vagiprev, for example, is under development by Vybion both as a spermicide and for the prevention of STIs. Our data also highlights another interesting product at a later stage of development, Indevus' compound PRO-2000. This topically-applied female contraceptive has strong STI prophylactic potential, and in direct support of this was awarded a grant from the Department for International Development, the UK, to support a 5yr programme including Phase III trials in Cameroon, S Africa, Tanzania, Uganda and Zambia in collaboration with the Medical Research Council (MRC) and Imperial College, London, UK. Various other chemical barrier agents are also in clinical trials.
In the absence of viable vaccines or chemical barriers to prevent bacterial STI transmission, the physical barrier - the redoubtable condom - remains the most important tool in the battle to prevent the spread of STIs and is almost 100% effective. While the challenge in the developed world remains persuading individuals of the merits of their use, the situation in the developing world is more complex. Although the US in its aid programmes, has advocated the 'ABC' approach (abstinence, being faithful, condom use), many have argued that this approach is not feasible in disempowered populations, such as racial minorities, gay men, and in particular, women. For this reason, the spread of universal human rights will be the single most powerful weapon in the battle against bacterial sexuallytransmitted infections.
Michelle Jenvey
Pharmaprojects Analyst
