Although the biggest news in Hepatitis C (HCV) / HIV coinfection continues to be direct acting antiretrovirals (DAA), discussions at the 19th International AIDS Conference went beyond the benefits of such drugs and started discussing some of the barriers to their use.
At a panel on the evolving landscape of co-infection, Gregory Dore got people thinking about the epidemiology of co-infection in high-risk communities. He pointed out that while only a relatively small number of HIV infected men who have sex with men (MSM) are co-infected with HCV; the opposite is true in injection drug users (IDU). Most of them have HCV but not HIV, and almost all HIV infected IDU have hepatitis.
That potentially presents a major treatment problem since IDU are not the most compliant patients when taking medication. And, as Dr. Dore pointed out, “without effective HIV management, including adherence to antiretroviral therapy, consideration of HCV treatment is problematic… If you can’t maintain or restore immune function, related to effective antiretroviral therapy, trying to address hepatitis C really shouldn’t be the primary focus.”
Furthermore he, and the other scientists on the panel, made the point that while Boceprevir and Telaprevir are exciting, it may be too soon to go about treating every co-infected patients. While interferon based treatments are still a necessary component of HCV therapy, it may make far more sense to continue to treat HCV as a liver disease rather than as a chronic infection. That means focusing therapy on individuals who have cirrhosis, and whose liver function is at risk, rather than trying to eradicate the virus in all patients just because it might be possible.
Although it may seem strange to have a potential cure for HCV and not use it, Dr. Susanna Naggie pointed out that while treatment responses in the DAA era are substantially higher than they were before such drugs were available, so are adverse events. In addition, current regimens are highly complex. Therefore, while they remain healthy, many patients may be better off living with chronic HCV until treatment becomes easier and more affordable.
As for assessing which patients should be fast-tracked for treatment, Dr. Dore made an eloquent case for the approval of Fibroscan as a screening technology in the U.S. As good at determining liver prognosis as biopsy, the Fibroscan machine is non-invasive and easier to use. That makes it a practical tool for screening the liver health of IDU in community clinics – something which biopsy often is not. It may also make it more practical to perform regular monitoring, with a frequency that would not be acceptable to patients with an invasive test.
Treating and monitoring HCV/HIV coinfection is important, but it would be even better if it could be prevented entirely. Scientists working on an HCV vaccine know that, in theory at least, their goal should be far easier to accomplish than that of scientists working on a vaccine for HIV. After all, 20 to 30 percent of people infected with HCV manage to clear the infection on their own. “That’s really important,” says Georg Lauer, a scientist from Massachusetts General, “because it tells us that, in contrast to HIV, complete control and eradication of this virus is actually possible, and so some sort of immune prevention is a real possibility.”
His group recently completed an early trial of a novel HCV vaccine in healthy volunteers. The initial data appeared promising. Not only did everyone respond to vaccination, but poly-functional T-cells were activated. That provided some hope that they might provide a real defense against the virus. However, it’s too soon to tell. Hopefully their next trial, a test of the vaccine in people who are actually at risk of HCV, will give a clearer idea of the efficacy of the immune response.
All in all, 2012 is an exciting time for HCV research. Although there are still barriers to treatment – financial, regulatory, and otherwise – it is becoming clear that over the next few years it will become possible to help just about everyone who is seriously impacted by the virus. At that point, HCV coinfection may stop being a barrier of its own – a roadblock in the fight against HIV.