Respiratory Syncytial Virus: Can antivirals make the grade?

Despite high disease incidence and associated mortality, there are currently very few products indicated for the prevention or treatment of respiratory syncitial virus. The high potential of this sector is demonstrated by the strong performance of MedImmune's Synagis. The industry is therefore awaiting the market entry of new treatments capable of meeting this unmet need.

The Market Brief 'Respiratory Syncytial Virus' gives an overview of the etiology and epidemiology of RSV infection, discussing the scale and seriousness of this disease. An analysis of current treatment and prophylactic practices is also included, highlighting current unmet needs in this sector. In addition, the RSV product pipeline is discussed, showing how pharmaceutical companies are addressing this unmet need to gain leverage in the RSV market. Finally, the brief provides an assessment of the commercial prospects for novel RSV products, describing likely scenarios and an estimation of peak annual sales.

High RSV incidence

In the US, Respiratory Syncytial Virus (RSV) is believed to cause up to125,000 hospitalizations annually. The seriousness of this disease was highlighted by a recent study that used RSV incidence data to predict the number of deaths resulting from this virus between the years 1990-1999.

This work demonstrated that RSV caused 2,707 underlying pneumonia or influenza deaths, 11,321 underlying respiratory and circulatory deaths and 17,358 all-cause deaths. Despite this, there are very few products currently available to treat or prevent this infection.

The leading RSV product, MedImmune's monoclonal antibody Synagis, is indicated for the prevention of RSV in at-risk infants, namely low birth-weight and very low birth-weight babies. The huge potential of this sector is clearly demonstrated by the strong and growing sales of this product, which achieved sales of almost $600m across the seven major markets in the year ending June 2003.

The success of Synagis also reflects the greater potential for prophylactic therapies in this sector, as opposed to therapeutic options. Datamonitor believes that both monoclonal prophylactic treatments and prophylactic vaccines have the potential to achieve peak sales in excess of $1 billion across the seven major markets.

Few treatment options

Valeant Pharmaceuticals' Virazole is currently the only therapy for treating RSV infections, but presents significant shortfalls in terms of administration, efficacy and safety profile. The product requires long periods of nebulization, which means the product can only be administered on an in-patient basis.

Clinical trial data that questioned previous studies regarding the efficacy of this drug have had a significant impact on its recent performance and it is now only prescribed for the severest RSV infections in the hospital. Datamonitor believes that an antiviral with demonstrated efficacy and a proven safety record, even when administered in a similar fashion to Virazole could achieve peak annual sales in the seven major markets approaching $300m.

Antivirals

Antivirals with more convenient administration, such as once-daily oral delivery, could potentially achieve greater sales through penetration of the community RSV sector, which has far greater patient potential.

Antivirals for the treatment of common respiratory tract infections (RTIs) in the community are not a novel concept, as both GSK and Roche market Relenza and Tamiflu, respectively, for the treatment of influenza. However, these two antivirals have not resulted in significant sales, despite the high incidence of influenza across the major pharmaceutical markets.

In the year ending June 2003, Tamiflu and Relenza only generated $159m and $7.2m, respectively. A number of factors, which contributed to the poor uptake of these compounds, could also limit the utilization of RSV antivirals within the community setting. Factors such as poor availability of rapid and accurate diagnostics to determine viral etiology, low disease awareness and sub-optimal presentation rates would limit the uptake of antiviral therapies.

Company strategy

Datamonitor believes that companies developing and marketing antivirals to combat RSV infection would be well served by forming alliances with diagnostic companies and those marketing complementary RTI therapies, both antivirals and antibiotics. In this way, physicians could be presented with a complete treatment package, which would allow rapid diagnosis and appropriate treatment of RTIs.

Such strategies would likely significant stakeholder support as they could help to reduce inappropriate antibiotic therapy and subsequently delay the development of resistance in the community. One of the key factors contributing to overuse of antibiotics, particularly the inappropriate treatment of viral infections, is patient pressure to receive some form of pharmaceutical therapy.

Providing the physician with the ability to diagnose the infection more accurately and alternatives to antibiotic treatment would provide clinical benefit, while also driving uptake of antiviral therapies.

If you found this week's Expert View useful, you may be interested in Datamonitor's reports:

• Respiratory Syncytial Virus: Can Antivirals Make the Grade? priced $1,700
• Stakeholder Opinions: Community Acquired Respiratory Tract Infections - Room for Ketek? priced $3,400
• Commercial Perspectives: Vaccines - Nosocomial Pathogens priced $9,600

To order these reports contact peter.barfoot@bioportfolio.com or telephone +44 1300 321501 or +1 415 680 2472 and a representative will get back to you.

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