Resistance to HIV drugs a growing problem

Data presented at the 2nd International AIDS Society conference in Paris demonstrated that 10% of newly diagnosed HIV patients have virus strains resistant to at least one anti-HIV drug. With large numbers of individuals remaining undiagnosed, an increase in drug-resistant strains of HIV could have significant implications for the future treatment of the disease.

Human immunodeficiency virus (HIV) is the causative agent of acquired immune deficiency syndrome (AIDS). Its diagnosis is made through analysis of viral RNA in human serum. Transmission of HIV is mainly through the blood route and approximately 50% to 90% of patients are symptomatic for acute viral infection.

According to independent market analysis from Datamonitor (DTM.L), approximately 43,000 people with HIV are still undiagnosed within the five major EU markets. It is uncertain how many patients therefore, could have resistant HIV strains.

Increasing resistance

The latest clinical studies presented at the 2nd International AIDS Society conference showed that 10% of European HIV patients have virus strains resistant to at least one anti-HIV drug. Datamonitor's research shows that for 2002 in the UK alone, this was roughly equivalent to 3,000 out of approximately 30,000 diagnosed HIV patients. The actual number may be higher due to the number of undiagnosed HIV-positive individuals.

Of the five major markets in the EU, France, Italy and Spain have the largest prevalence of HIV. Datamonitor estimates that within these three countries, there may be around 35,000 individuals harboring resistant strains of HIV.

Given that within the five major EU markets, approximately 58% are diagnosed with HIV, this implies there are almost 200,000 individuals unaware of their HIV status, possibly harboring resistant HIV strains. These individuals may engage in high-risk activities such as intravenous drug use, commercial sex activities and practicing unsafe sex. This will further spread the virus and exacerbate the epidemic.

Datamonitor's research indicates that individuals diagnosed and treated may need to be placed on more aggressive treatment regimens in order to overcome resistance from single or multiple drug resistant virus strains. This may in turn generate increasing incidence of resistance, especially since patients are less likely to comply with strict and aggressive therapy. Non-compliance consequently reduces the effectiveness of the current arsenal of HIV drugs.

The need for new treatments

The leading pharmaceutical companies are nevertheless looking to respond to this emerging problem. The US HIV treatments market (total $3.3 billion, 2002) is an attractive but challenging option for major pharmaceutical companies. High-unmet medical need, short product life-cycles and intense societal pressure call for an increased dimension of complexity when searching for commercial value.

Roche, Gilead Sciences and Bristol-Myers Squibb (BMS) have all received FDA marketing approval for their drugs; Fuzeon, Emtriva and Reyataz, during the first half of 2003. Both Fuzeon and Reyataz have shown good activity in treatment-experienced patients.

Fuzeon is indicated for heavily treatment-experienced individuals with a number of resistant viral strains, or salvage patients. Healthcare workers and advocates of Fuzeon, including HIV patients, are already heralding this a 'miracle drug'.

Fuzeon is the first member of the ‘fusion inhibitor’ class. Datamonitor predicts it will play an increasingly significant role in the treatment-experienced population, especially in those with multiple treatment failures. Expanding on current indications for the drug is also imperative for Roche to sufficiently penetrate the market during the next five to seven years.

BMS' Reyataz, a protease inhibitor, is another product with significant activity against resistant viral strains. Datamonitor believes this drug will also play a significant role in suppressing viral load in regimens given to late stage patients. Emtriva has shown good efficacy in both early and late stage patients.

An uphill battle

Given that the research shows a significant proportion of individuals with resistant viral strains, the launch of these new drugs against HIV have come at an opportune moment, both for the drug manufacturers concerned and patients alike.

However, Datamonitor warns that the current anti-HIV arsenal is still very limited - with millions of individuals not yet treated, and as resistance continues to increase, HIV drug manufacturers will no doubt be fighting an uphill battle to keep pace with the epidemiology of the disease and fast mutation rate of the virus.

"The introduction of three novel anti-HIV compounds almost in tandem will no doubt result in renewed global optimism among patient groups," commented Dr Dheeraj Khiytani, senior analyst at Datamonitor.

"Whilst a cause for celebration, patient groups should note that the battle with HIV is only just starting. New drug launches will definitely keep patients healthy for longer and will decrease transmission rates by reducing viral load. However, they key to defeating the pandemic must definitely come in the form of prevention - the only guaranteed way to defeat the virus."

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

• Commercial Insight: HIV in the USA - Increasing Choice, Flexibility and Competition priced $12,800
• Stakeholder Opinions: HIV/HCV Co-infection - Whose Niche? priced $3,200
• Market Dynamics: HIV - Combating a Market Slowdown priced $6,400

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