GSK and Pfizer HIV divisions to form new company

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GlaxoSmithKline (GSK) and Pfizer have merged the HIV sections of their business to form a new company. In a statement issued on April 16th, they said the new company “would be more sustainable and broader in scope” than the businesses of the two companies.

The new company will have a portfolio of eleven licensed anti-HIV products, plus six promising investigational drugs in phase I and phase II clinical trials. The licensed drugs include GSK’s combination pills Combivir (AZT and 3TC), Kivexa (abacavir and 3TC) and Trizivir (abacavir, AZT and 3TC). Pfizer’s sole licensed anti-HIV drug is the CCR5 inhibitor, maraviroc (Celsentri).

These and other products, notably GSK’s protease inhibitor fosamprenavir (Telzir), currently account for 19% of the current market for anti-HIV drugs. However, they have been eclipsed in recent years by drugs with a more favourable safety profile. Because of concerns about the risk of fat loss caused by AZT, Combivir is no longer a choice for first-line antiretroviral therapy.

Glossary

first-line therapy

The regimen used when starting treatment for the first time.

CCR5

A protein on the surface of certain immune system cells, including CD4 cells. CCR5 can act as a co-receptor (a second receptor binding site) for HIV when the virus enters a host cell. A CCR5 inhibitor is an antiretroviral medication that blocks the CCR5 co-receptor and prevents HIV from entering the cell.

phase I

The first stage of human testing of a new drug or intervention, typically involving a small number (10-100) of participants who do not have the condition the drug is intended to treat. Phase I clinical trials evaluate safety, side-effects, dosage and how a drug is metabolised and excreted in the body.

equivalence trial

A clinical trial which aims to demonstrate that a new treatment is no better or worse than an existing treatment. While the two drugs may have similar results in terms of virological response, the new drug may have fewer side-effects, be cheaper or have other advantages. 

treatment-experienced

A person who has previously taken treatment for a condition. Treatment-experienced people may have taken several different regimens before and may have a strain of HIV that is resistant to multiple drug classes.

Research suggesting that abacavir can increase the risk of heart attack (disputed by GSK) and work less well in patients with a high viral load, led to Kivexa being downgraded from first-line HIV treatment in recent US guidelines. Although it is still an option for first-line HIV treatment in the UK, its use is not recommended for patients with a risk of heart disease or a viral load above 100,000 copies/ml.

Although an important option for some treatment-experienced patients, there has been little demand in the UK for Pfizer’s maraviroc. Research failed to show that it was equivalent to efavirenz, dashing hopes that the drug would break through into the lucrative first-line market.

Hopes will therefore be focused on the new venture’s six products currently in development. In phase two clinical trials are an integrase inhibitor, two NNRTIs and a CCR5 inhibitor. A CCR5 inhibitor is also in phase I studies, as is a pharmacokinetic enhancer.

“Today marks a definitive step by GSK to renew our focus and deliver more medicines, more efficiently to more people with HIV…at the core of this specialist business is a broad portfolio of products and pipeline assets”, said Andrew Witty, GSK’s CEO. “We are creating a new global leader in HIV and reaffirming our ongoing commitment to the treatment of the disease”, commented Pfizer’s CEO, Jeff Kindler.

New research will also be a priority of the new company, which has also committed itself to community support. GSK’s Positive Action will transfer to the new company. There is also an undertaking to provide not-for-profit medicines in resource-limited countries.