HIV Weekly - February 21st 2006

Welcome to HIV Weekly, a weekly email bulletin that provides people with, or affected by, HIV a concise, plain English digest of a selection of the very latest HIV news.

This new digest puts the latest HIV news stories into their context to equip you with the knowledge to understand what the latest research might mean for your HIV treatment and care.

Information on the latest NAM treatment information resources and those produced by other key organisations such as the UK Coalition and THT are also included.

HIV Weekly is edited by Michael Carter, NAM's patient information and news editor.

This week’s edition is, once again, devoted to news from the Thirteen Conference on Retroviruses and Opportunistic Infections (CROI) which was held in Denver earlier this month. CROI is one of the major HIV conferences of the year and this year’s conference was particularly interesting with lots of important information presented on all aspects of HIV.

This edition of HIV weekly is divided into four main sections:

• New drugs: Progress reports on the two important new drugs currently in clinical trials – the non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC 125 (etravirine) and the protease inhibitor TMC 114 (darunavir); the protease inhibitor atazanavir (Reyataz) is safe and effective in people who have never taken HIV drugs before.
• Tests: A study in the UK has shown that more people than expected had a gene mutation that causes a severe allergic reaction to abacavir (Ziagen).
• Illness: A surprising proportion of HIV-positive patients develop a severe illness when their CD4 cell count suggests that they are not at risk.
• HIV and hepatitis: It may be possible to tell after four weeks if anti-hepatitis C treatment will work in HIV-positive people coinfected with the hardest to treat strains of hepatitis C.

If you want to know more about what research presented to CROI might mean for you, then come to the next NAM information forum on February 27^th. Details are provided below.

New drugs

Tests

Abacavir (Ziagen) is an anti-HIV drug in the nucleoside reverse transcriptase inhibitor class. It is available in a combined pill with 3TC (lamivudine, Epivir) called Kivexa  and abacavir and 3TC is one of the nucleoside ‘backbones’ to HIV treatment currently recommended in the UK for people starting HIV treatment for the first time. Abacavir is also available in a combined pill with 3TC and AZT (zidovudine, Retrovir) called Trizivir.

Abacavir can cause a severe allergic reaction in approximately 4% of people who take it. Symptoms normally develop in the first few weeks of treatment with the drug and usually involve nausea, sickness and tiredness. All packs of abacavir contain a card warning about the symptoms of this allergic reaction (often called a hypersensitivity reaction) and what to do if it develops. If you stop taking treatment because you are allergic to abacavir you must never take the drug (or any pills contain abacavir) again because this can cause a potentially fatal drop in blood pressure.

A test has been developed to see who might have a greater risk of developing an allergic reaction to abacavir. It looks for a gene called HLA-B*5701. The frequency with which the gene occurs differs according to a person’s racial background. It is thought to be most common amongst northern Europeans and people of northern European descent and less common amongst non-Caucasians.

Research conducted in Brighton and presented to CROI found that 14% of people tested positive for the HLA-B*5701 gene and that it occurred in 16% of white people and 9% of black people. The study was quite small, and only involved 114 people.

No allergic reactions to abacavir were seen in people who tested negative for the gene and then started treatment with the drug.

Overall, 6% of people treated at the clinic where the study was conducted experienced an allergic reaction to abacavir.

Illness

CD4 cell counts are a key test used to monitor HIV disease progression. CD4 cells are immune system cells which play a vital role in the body’s response to infections. HIV attaches itself to a molecule on the surface of CD4 cells and then enter and destroy the cell.

The CD4 cell count in a healthy person without HIV is normally between 600 – 1200 cells/mm^3.

By looking at the trend in your CD4 cell count over time, you and your doctor can decide when you need to take action that can improve your health. Current UK HIV treatment guidelines recommend that anti-HIV treatment should be started if your CD4 cell count is between 250 – 200. When your CD4 cell count falls to this level you are at risk of developing certain AIDS-defining and potentially life-threatening infections. Some infections, such as PCP pneumonia can develop when your CD4 cell count is around 200, whereas other illness, for example cytomegalovirus (CMV) normally only occur when a person’s CD4 cell count falls to below 100. However, tuberculosis, the commonest AIDS-defining illness in the world and one of the commonest in the UK, can occur when a person has a relatively intact immune system.

In a large European study presented to CROI, researchers divided seven AIDS-defining illness according to the CD4 cell count at which they normally develop – 100 or above; 200 or above; and 300 and above.

The researchers found that approximately 2% of all AIDS-defining illness occur when people have a CD4 cell count higher than that normally associated with a risk of illness developing. 

They also found that taking anti-HIV treatment cut the risk of AIDS-defining illnesses occurring in people with CD4 cell counts above 200 by over 50%. A viral load over 1,000 was also associated with an increased risk of developing an AIDS-defining illness.

TB was particularly likely to develop in people whose CD4 cell count was over 300 if they were an injecting drug user.

The SMART treatment interruption study which was stopped earlier this year on grounds of safety, found that some AIDS-defining illness occurred at higher than expected CD4 cell counts in people who were taking a break from HIV treatment.

HIV and hepatitis

A test after just four weeks can predict if anti-hepatitis C treatment is going to work in HIV-positive people who have the hardest to treat strains of hepatitis C, according to a presentation to CROI.

Treatment with pegylated interferon and ribavirin is the currently recommended treatment for hepatitis C virus. The duration of treatment varies according to which strain – or genotype – of hepatitis C a person is infected with. In people with genotypes 2 or 3, 24 weeks of treatment is recommended, however if a person is infected with genotype 1, the hardest to treat of all the genotypes, 48 weeks treatment is recommended.

Treatment for hepatitis C works less well in people who also have HIV than those who only have hepatitis C and it can have unpleasant side-effects.

Researchers found that a response to hepatitis C treatment after just four weeks predicted which people infected with HIV and hepatitis C genotypes 1 or 3 would respond to treatment. Measuring treatment response after four weeks could be “a useful tool to individually adjust the duration of treatment”, researchers concluded.