Understanding Structured Treatment Interruptions

A little more than a decade ago, researchers and health-care experts thought structured treatment interruptions (STIs) held a lot of potential for the treatment of human immunodeficiency virus (HIV). Anti-HIV medication regimens are expensive, complex, and overwhelming. Plus, there’s the potential for drug toxicity and severe side effects. However, additional research cast doubts on this planned break from HIV treatment, making it much more controversial among health-care professionals.

What Is a Structured Treatment Interruption?

Human evolution spans thousands of years. Disease evolution doesn’t always require that much time. In the case of HIV, evolution can occur quickly, sometimes even within the same day. Each day, our bodies make millions of new cells. When HIV invades the body, it begins replicating and creating increasingly higher amounts of HIV-infected cells. Anti-HIV medication is designed to slow down or interrupt this replication process. However, HIV-infected cells can begin mutating and may become resistant to the medications. 

That’s where the idea behind structured treatment interruptions, or drug holidays, began. Researchers wondered: If a patient becomes resistant to a particular medicine, could taking him or her off the medicine revert the cells to their non-resistant form? That would mean that the patient would be able to take the medicine again and have it be just as effective at defeating the infected cells as it was before the cells mutated. Several initial, small-scale studies showed that yes, a drug holiday, or STI, was effective at reducing the number of drug-resistant cells. Most doctors were hesitant to adopt the new method of treatment, however, without first seeing results from much larger studies. When larger studies began to look at the use of STIs in HIV treatment, the science seemed less solid.

The Risks of STI

The Strategies for Management of Anti-retroviral Therapy (SMART) study, which was conducted from 2002 to 2006, studied more than 5,000 HIV-positive individuals and their bodies’ reactions to STI. Their results: People who took drug holidays had a greater risk of death, and they were more likely to suffer severe side effects, such as heart, kidney, or liver disease, than people who remained on their medicine therapy continually. The research was so clear, in fact, that the doctors behind it cut short the study because the risk to patients was too great. 

The study found that when patients discontinue their antiretroviral therapy, many suffer viral rebound (their viral load increases), decreased immune system function, and clinical progression.

If you choose to take a drug holiday, do so only when you have clear guidance from your doctor. He or she will likely want to monitor you regularly, checking your viral load, risk for infection, CD4+ T-cell levels, and disease progression.

The Benefits of STI

Contrary to the SMART study, some smaller European studies have found that STI can be just as effective as HAART—which is often referred to a cocktail therapy—in people looking to prolong their lives and reduce the symptoms of HIV.

People with poor adherence to their antiretroviral therapy may choose to take a drug holiday because their body is reacting negatively to the medicine. Other reasons a drug holiday may be useful: multidrug resistance, when cells become resistant to more than one type of anti-HIV medication; transitioning to an alternative treatment; reducing toxicity caused by medicines; or transitioning off all medication entirely.

How to Talk to Your Doctor

Today, the more popular and more commonly used method to prevent drug-resistant HIV is cocktail therapy, or HAART. A combination of drugs is less likely to cause drug-resistant mutated cells than a single drug. However, your doctor may be willing to let you take a drug holiday, depending on your individual circumstances. If not, and you still wish to explore the option, seek out another doctor or health-care professional who can weigh the pros and cons of a drug holiday with you.