New antiretroviral agent for patients with drug resistant HIV

Maraviroc is a new antiretroviral agent that prevents HIV from binding to CD4 cells⇑. The phase III drug trials supporting maraviroc’s approval by the US Food and Drug Administration have now been published and show that it suppresses viral replication significantly better than placebo in people with late stage disease. The 1049 participants in two identical trials had already been treated unsuccessfully with three other classes of antiretroviral or had developed resistance. All participants continued with the best available background therapy during the trial, which lasted 48 weeks. People who took maraviroc developed no more side effects than controls.

Maraviroc looks like an effective new weapon against HIV, although it is active against only one particular viral phenotype. Patients must be tested for the R5 type before they begin treatment, which adds logistical complications not shared by previous drug classes, says an editorial (p 1509). Since R5 viruses tend to predominate earlier rather than later in HIV infection, it might make sense to test the new agent at an early stage. Maraviroc blocks a host protein—a receptor on CD4 cells—rather than attacking HIV directly. But the usual cautions about resistance still apply, says the editorial. More than a third of patients in both trials discontinued their maraviroc early. The most common reason was that it had stopped working.

One reader or two for screening mammograms?

In general, two experts read mammograms more accurately than one, although new research suggests that a single reader armed with a computer aid can be an effective alternative. In a large trial from the UK, a single reader helped by a computer program detected as many breast cancers as two readers. Twenty eight thousand women were screened with both reading regimens. Double reading detected 199 of 227 cancers (87.7%). Single reading aided by computer detected 198 (87.2%). The two methods …