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Antiviral antibody development

Substantial progress has been made in the development of novel antiviral therapies over recent years, but the majority of new and existing products only inhibit, rather than curing, the infection. There is still no available vaccine, or other preventative measure, for many viral infections. At the same time, many antivirals are suffering from unfavorable side effect profiles and emerging resistances. Antibody agents in development for viral infections such as HIV and Hepatitis C (HCV) could potentially help in overcoming these issues.

While current HIV and HCV therapies are associated with resistance and toxicity issues, the pressing unmet need lies in disease prevention and cure. Unfortunately, the majority of antibody agents in development are not addressing this issue. Datamonitor forecasts that this factor, combined with their intravenous mode of administration, will seriously restrict their use in these indications.

Antibody agents actually have a bigger role to play in the treatment and post exposure prophylaxis of infections such as rabies, SARS and West Nile virus, for which there are no effective treatments or preventative measures available. Unfortunately, although infected individuals often require immediate protection, the markets for these indications are relatively small and possibly not commercially viable.

Antibody treatments for nosocomial infections

The need for alternative strategies to prevent and treat nosocomial infections has increased owing to a rise in the number of medical procedures and the number of immuno-compromised patients, alongside the growing resistance to conventional antibiotic therapy. Antibody-based products can offer patients fast and immediate protection, and will benefit those unable to mount a sufficient immune response, such as infants, the elderly and immuno-compromised patients.

Ongoing difficulties in identifying suitable targets on bacteria and defining high-risk patient populations are just some of the obstacles that manufacturers face in the development of these agents. Moreover, given antibodies' specificity and cost, their use will be restricted to either prior microbiologic diagnosis of the infection, or a high prevalence rate of the respective pathogen, limiting their use to a small number of patients, in whom the benefits are well defined.

Since MRSA is the most common pathogen causing nosocomial infections, it has formed the most popular target for antibody development. However, despite concerns over resistance, there are still several antibiotics available that can treat multi-drug resistant strains of S. aureus. Because of this, antibodies are likely to have a limited role in the treatment of S. aureus infections in the medium term, but may form effective prophylactic agents.

In the hospital environment, the greater need lies in the shortage of effective treatments for Pseudomonas and fungal infections. The hypervariability of Pseudomonas, however, has made the identification of targets for both antibody and vaccine development extremely difficult. Antifungal antibodies are likely to be more successful commercially, given the persistently high mortality rates associated with candidiasis, and a slowly increasing prevalence of resistance to current antifungals. Severely immuno-compromised patients, who are most at risk from such infections, will benefit most from this immunotherapeutic approach, which augments or replaces the host immune response. As such, anti-candida antibodies would form an attractive adjunct to conventional antifungal therapy.

 

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