Roche to halt HIV drug research

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Roche, the manufacturer of saquinavir (Invirase) and enfuvirtide (Fuzeon) has informed HIV clinicians and treatment advocates that it is halting research into new HIV drugs.

The company has concluded that pre-clinical CCR5 antagonists and reverse transcriptase inhibitors under investigation would not provide a `true incremental benefit to patients`, according to a letter circulated last week.

The announcement ends a lengthy involvement in the HIV field for Roche, a company that has often been first but never very lucky in the search for successful HIV drugs.

Glossary

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.

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.

reverse transcriptase

A retroviral enzyme which converts genetic material from RNA into DNA, an essential step in the lifecycle of HIV. Several classes of anti-HIV drugs interfere with this stage of HIV’s life cycle: nucleoside reverse transcriptase inhibitors and nucleotide reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). 

preclinical

In vitro research or research involving animals, undertaken prior to research in humans.

fusion inhibitor

Anti-HIV drug targeting the point where HIV locks on to an immune cell.

Roche’s first antiretroviral product, zalcitabine, or ddC, (Hivid) was the third agent to be licensed, but its toxicity made the drug a white elephant within months of licensing. The drug was phased out altogether in 2005 due to lack of demand.

Roche was also at the forefront of protease inhibitor development with saquinavir, a drug hobbled by a development history that led to the exposure of thousands of patients to a sub-optimal dose of the drug – leaving them resistant to the first generation of protease inhibitors – and by failures in formulation of the drug that left it lagging far behind its competitors despite potentially better tolerability.

However Roche’s biggest problem came with the development of T-20, or enfuvirtide, the first, and so far, the only fusion inhibitor. Roche sunk millions into the development of Fuzeon in the hope that its investment would give the company a lead in the field of peptide-based drugs.

But Fuzeon was difficult to use and, due to its injectable nature, remained a niche product for highly treatment-experienced patients. Within three years of licensing it had been pushed aside by the arrival of the integrase inhibitor raltegravir, an oral entry inhibitor (maraviroc) and a new protease inhibitor for treatment-experienced patients (darunavir).

As if that wasn’t enough to sap commitment to HIV research, Roche was hit in 2007 by the discovery that a fault in the manufacturing of a batch of its in-licensed protease inhibitor nelfinavir had been contaminated by a chemical used in cleaning of the plant, leading to a possible cancer risk for those who took it. Nelfinavir had to be pulled from the market, ending its decline from darling of prescribers to also-ran to the more potent ritonavir-boosted protease inhibitors.

As recently as 2005 Roche was enthusiastically pursuing research into new protease inhibitors, CCR5 antagonists and reverse transcriptase inhibitors, but last week’s announcement indicates the extent to which it is now difficult for companies to project returns on investment in the HIV field. Outside the discovery of new drug classes, companies need to show substantial benefits to `me-too` drugs compared to the current standard of care, a challenge that is proving hard to meet as drugs become more potent and better tolerated.

Roche does not rule out the in-licensing of future products to treat HIV, but says it is re-allocating research resources away from HIV towards other viral infections.

Roche’s announcement will not affect the manufacture of existing antiretroviral products, nor the work of its Molecular division on its Amplicor HIV viral load test, an area in which the company has enjoyed more consistent success. Most importantly, it will not affect Roche’s commitment to hepatitis C research, where the company’s pegylated interferon product Pegasys remains at the forefront. Roche says it has a promising pipeline of products for the treatment of hepatitis C.