Virus-specific T-cell (VST) therapy is a type of cellular therapy. It helps the immune system fight viruses that can occur in immunocompromised people after a hematopoietic stem cell transplant (HSCT) or solid organ transplant. VST therapy is experimental. Researchers are studying it to see how well VST treats these viruses and if it can prevent them from occurring. So far, the results are promising.

What Viruses Does VST Therapy Target?

VST therapy targets five viruses that are common in many people:

  • Adenovirus (ADV)
  • BK virus
  • Cytomegalovirus (CMV)
  • Epstein-Barr virus (EBV)
  • JC virus

When people with a healthy immune system are exposed to one of these viruses, they typically recover from the initial infection. The virus “stays asleep” inside their body. When someone has a weakened immune system, the virus can “wake up. It can cause life-threatening complications. People who have had an HSCT or solid organ transplant are at high risk of this happening.

Before VST therapy, the only treatment option was anti-viral drugs. These drugs are not always effective. They can cause organ damage and other unwanted side effects.

Who Provides VST Therapy?

VST therapy is a highly specialized treatment that is only available at a small number of hospitals. Cincinnati Children’s offers VST therapy as part of several research studies. The therapy is available for children and adults who qualify for one of these studies.

What Does VST Therapy Involve?

VST therapy is given through an infusion (using an intravenous, or IV, line). It contains T-cells created to fight the viruses. These T-cells will give an immune response against a specific virus or viruses.

Scientific labs make VST therapy products. The T-cells in VST therapy come from donated blood. To be effective, the VST product must contain T cells for the specific virus infecting the patient. For example, if the donor blood does not contain T-cells that know how to control adenovirus, the VST product will not produce an immune response against adenovirus.

Where Do VST Products Come From?

VST products can be donor-derived or third party. The care team will choose the product with the best chance of fighting the specific virus affecting your child.

  • Donor-Derived: Blood was donated by the bone marrow donor who donated the stem cells used in the transplant. This blood is used to make a specific VST product for that patient.
  • Third party: Blood was donated by a healthy donor. It may be used for multiple recipients. The lab has already used it to make a VST product. This “off-the-shelf” product is stored and available for patients who have the right match.

Cincinnati Children’s is the only hospital in the country currently offering third-party VST products. This study is open to immunocompromised people who have developed infection with CMV, EBV, ADV, BK or JC virus. Any hospital or medical provider can refer a patient for this study.

Is VST Therapy Effective?

Based on research at Cincinnati Children’s:

  • Eighty percent of patients who had donor-derived VST therapy benefited.
  • Sixty-six percent of patients who had third-party VST therapy benefited.

“Benefited” means that their infection went away or got better in some way. This is very significant. Before VST, many of these patients’ infections did not respond or were resistant to anti-viral drugs.

Also, very few of the patients who received VST therapy had complications from the therapy.

Can VST Therapy Prevent a Viral Infection?

Cincinnati Children’s has an open research study that is using donor-derived VST therapy to prevent viruses after HSCT. The hospital recently received federal funding to study VST therapy further.

The Future of VST Therapy

Virus-specific T-cell therapy is a new and growing field in medicine. It has been an effective helpful treatment option for many people. Researchers hope that VSTs will one day make viral infections a non-issue after HSCT or solid organ transplant.