PET Scans Used to Detect HIV Progression

Positron emission tomography (PET) scans can track the progression of HIV and could lead to new treatment options and the development of the next generation of AIDS drugs, according to two recent studies. PET scans, usually used to identify cancerous tumors, could help fight AIDS by identifying the virus' impact on lymph nodes, which could be treated with radiotherapy or surgery.

Dr. C. David Pauza and colleagues at the University of Maryland Biotechnology Institute in Baltimore took whole-body PET scans of 15 HIV patients and found fairly distinct sites of immune response during different stages of the disease. "We believe that if we identify those sites clearly during HIV infection we encourage people to consider these types of interventions," Pauza said in an interview, referring to surgery or radiotherapy.

The scans showed that during early HIV, lymph nodes in the head and neck were activated, but in later stages the virus stimulated an immune response in areas of the torso and later in the bowel. Surgery or radiotherapy would open up a new approach to treating HIV/AIDS. "We are not aware that it has ever been tried," said Pauza. "We think it is appropriate to consider these approaches and also to learn from the cancer models because cancer is a disease of chronic cell activation and growth and in some ways, even though HIV is triggered by a virus, it has some similarities," he added. The report, "Whole Body Positron Emission Tomography in Patients with HIV-1 Infection," appeared in the Lancet (2003;362(9388):959-961).

David Schwartz and Sujatha Iyengar, of the Johns Hopkins University Bloomberg School of Hygiene and Public Health, also used PET scans to track HIV progression. They said lymph node removal could give patients an opportunity for a break in antiretroviral treatment in their study, "Anatomical Loci of HIV-Associated Immune Activation and Association with Viremia," also published in the Lancet (2003;362;(9388):945-950). "Although many systemic sites from which latent virus could be re-activated would be left, re-activation might not occur for months or years after removal of the active nodes, thereby allowing extended interruption of treatment," the scientists noted.

Pauza suggested that with the pattern of progression detected with PET scans, it might be possible to develop a prognostic tool for HIV and new drugs for patients in whom existing therapies have failed.

"One thing we discovered as we were going through this work is that there was a substantial amount of undiagnosed cancer associated with HIV. We observed a number of patients with lymphoma," he said.

Back to other news for September 26, 2003