Worth $8 billion in 2006, the HIV market is expected undergo significant changes as it expands to an estimated $11.5 billion in 2016. Patent expiries on key drugs and product launches in new and existing classes are set to reshape the HIV treatment paradigm. One player set to lose out as its ageing HIV portfolio loses its patent protection is the current market leader, GlaxoSmithKline.

Market set to change significantly

Since the launch of the first antiretroviral, Retrovir in 1997, GSK has dominated the HIV market. In 2006, it accounted for 30% of total antiretroviral sales. However, this marked a notable decline from 2005 when it accounted for 33% of the overall market. Although GSK currently has eight marketed products, the majority are relatively old and at least five of them are expected to lose patent protection by 2014. As a result, GSK's market share may be drastically reduced by 2016 if it does not find successful new products. However, the sector as a whole is set to expand as new launches will ultimately change highly active antiretroviral therapy (HAART) regimens for both early and late stage therapy, and other companies are set to take a larger share of the market.

Gilead and Bristol-Myers Squibb (BMS) are the second and third leading companies in HIV. The success of Viread and Truvada has led to Gilead rapidly gaining market share with the company's HIV portfolio accounting for 23% of total antiretroviral sales in 2006. The collaboration between Gilead and BMS resulted in the first cross-class fixed dose combination (Atripla) consisting of Truvada and Sustiva. Atripla combines all three components of HAART – two nucleoside reverse transcriptase inhibitors (NRTIs) and a non-nucleoside reverse transcriptase inhibitor (NNRTIs) – into a single pill that can be taken once daily. It generated first year sales of $174 million in the US alone owing to its simplicity and convenience. Atripla is expected to be launched in the EU in H2 2007 and Datamonitor believes it will dominate first-line therapy and generate substantial sales for Gilead and BMS.

A recent entrant into the HIV market is Tibotec/Johnson & Johnson (J&J), which currently only have one marketed product, Prezista. A future broader label for this protease inhibitor (PI) and the potential launches of the company's developmental NNRTIs are likely to generate significant revenues for the company, making Tibotec/J&J one of the leading HIV companies by 2016.

New products will reshape established treatment paradigms

The reformulation of existing drugs into fixed dose combinations such as Gilead and BMS' Atripla, and the increased availability of once-daily therapies such as Abbott's Kaletra and BMS' Reyataz, have simplified early lines of treatment . Such therapies have more convenient dosing schedules and have a significantly reduced pill burden, thereby improving the quality of life for patients.

Additionally, the launch of several new drug classes such as CCR5 inhibitors and integrase inhibitors from 2007 onwards will significantly change treatment paradigms for late-stage therapy as they will give rise to countless new drug combinations for this patient population. Atripla, a fixed dose combination of Truvada and Sustiva, has been the first drug to combine the components of HAART into a single pill that can be taken once-daily resolving the issue of a high pill burden and complicated dosing regimen traditionally associated with the PI class.

Tibotec/J&J's PI Prezista is currently only approved for treatment-experienced patients. A once-daily formulation of the drug was recently compared against the current leading PI, Kaletra, in a Phase III trial called ARTEMIS in treatment-naive patients (those that have never received any form of HIV treatment). Data from this study supports the use of Prezista in early-stage therapy where it could become the preferred PI for first-line patients.

Datamonitor forecasts Prezista to become the leading PI by 2016, accounting for 27% of the HIV protease inhibitor market. Tibotec also has two NNRTIs in development, etravirine and rilpivirine. The company has filed a new drug application for etravirine based on data in trials in treatment-experienced patients and has designed a Phase III program for rilpivirine in treatment naive patients. Datamonitor expects a US launch for etravirine early 2008.

By 2016, Datamonitor expects new drugs to account for almost half of total antiretroviral sales across the six major markets of UK, US, France, Germany, Italy and Spain. New classes of drugs such as Pfizer's recently approved Selzentry/Celsentri (CCR5 inhibitor) and Merck & Co.'s Isentress/raltegravir (integrase inhibitor) offer a novel mechanism of action and are therefore effective against strains of HIV that are resistant to currently available classes. Selzentry has been approved for treatment-experienced patients and it is likely Merck's Isentress will be approved for the same patient population.

Other developmental drugs from these classes include Schering Plough's CCR5 inhibitor vicriviroc in Phase III development and Gilead's integrase inhibitor elivitegravir in Phase II development. Also in Phase II development are Panacos's maturation inhibitor bevirimat, and Tanox's attachment inhibitor TNX-355. Bevirimat targets the viral maturation process while TNX-355 is a CD4 receptor inhibitor. So while the patent expiry of many of the currently efficacious and financially successful drugs is bad news for drugs developers, the good news for HIV patients is that there are a number of novel and very promising treatments in the development pipeline.

Related research:

• Infections - AIDS HIV Drug Pipeline Report
• Commercial Insight: HIV - Reshaping Treatment Paradigms
• Commercial Insight: HIV - Change of guard
• Pipeline Insight: HIV - Extending treatment options