Bone marrow transplant is a crucial treatment for patients with blood cancer as well as those who have immunodeficiency and hematologic disorders, but the procedure also poses risks of life-threatening infection as it often follows intensive radiation therapy or chemotherapy that destroys the patient's immune system.

In patients who had their damaged bone marrow, the soft and fatty tissue found inside the bones, replaced with new bone marrow stem cells, most develop serious viral infections which can be fatal in up to 20 percent of the cases. Antiviral medications for these infections can be very prohibitive, toxic and even ineffective.

A new study conducted by Ann Leen, from the Baylor College of Medicine in Houston, Texas, and colleagues found a safe, fast and effective approach that could protect patients with compromised immune system from severe and potentially fatal infections using engineered virus-specific T Cells.

T cells are a type of blood cells that help the body fight infection, but for individuals who underwent bone marrow transplant, the cells become incapable of providing efficient protection from infections.

For the study published in the Science Translational Medicine on June 25, Leen and colleagues involved 11 patients who had allogeneic bone marrow transplant, which means that the stem cells they received were from another person, eight of whom had up to four active infections.

The researchers grew T cells and engineered these to target five viruses namely BK virus, cytomegalovirus, Epstein-Barr virus, adenovirus and Human Herpesvirus 6 (HHV6) and then gave these to the 11 patients. The T-cells that were given to each of the patients came from the blood of the person who donated the bone marrow they received.

The researchers observed that the virus-specific T cells (VSTs) overall produced promising results that lasted long term.

"These VSTs proved safe in all subjects and produced an overall 94% virological and clinical response rate that was sustained long-term," the researchers wrote.

Study author Helen Heslop, also from the Baylor College of Medicine, said that because the engineered T-cells can be produced in as little as 10 days, the therapy could be used to treat viral infection in more patients and provide them with long term protection.

"This study translated improved manufacturing techniques developed in Dr. Leen's laboratory to the clinic and showed that virus specific T cells produced with the new method could target new viruses and be ready for clinical use after 10 days," Heslop said.

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