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New research shows success training t-cells to recognize and fight life-threatening viruses

Children's is the only U.S. pediatric hospital that manufactures specialized T-cells from native cord blood

Patients with leukemia, lymphoma, other cancers, and genetic disorders who receive stem cell or cord blood transplants face the post-transplant risk of developing a life-threatening infection with adenovirus, cytomegalovirus (CMV), or Epstein-Barr virus (EBV).

The study reports the results of a head-to-head comparison of two powerful immunotherapeutic strategies to thwart such viral infections. Both therapeutic approaches leverage the power of multivirus-specific, donor-derived T-cells (mCTL), which are highly skilled at recognizing foreign invaders and, in the case of the peripheral blood cells, have long memories of past battles.

The award-winning paper, “Multivirus-Specific T Cells From Both Cord Blood and Bone Marrow Transplant Donors” was presented during the International Society for Cellular Therapy (ISCT) 2016 Annual Meeting, held from May 25 through May 28, in Singapore. The abstract’s lead author, Patrick J. Hanley, PhD, Laboratory Facility Director of Children’s Cellular Therapy and Stem Cell Processing facility, was recognized by ISCT with a Young Investigator award during the meeting.

Nine research scientists and clinicians affiliated with Children’s National Health System are co-authors of a paper, including Michael D. Keller, MD, the lead clinical investigator of the peripheral blood T-cell study, and Catherine M. Bollard, MBChB, MD, the study’s sponsor and Director of Children’s National Program for Cell Enhancement and Technologies for Immunotherapy.

After certain treatments, some cancer patients’ bodies are stripped of their natural ability to fight infection. The stem cell or the cord blood transplant restores the body’s ability to produce a full complement of blood cells, including infection-fighting white blood cells. As a further boost to these patients, the T-cells are trained to spot and neutralize all three potentially lethal viruses (CMV, EBV, and adenovirus) simultaneously. The personalized cell therapy can be accomplished in a single infusion and administered in the outpatient setting.

In the phase I perspective study, the personalized T-cells were grown from peripheral blood (PB) of adult donors who were seropositive for CMV, a relative of the virus that causes chickenpox, and were also coaxed to grow from naïve cord blood (CB). These naïve cells need additional training since they have never been to battle.

Since the mid-1990s, PB has been shown to be effective for such use. Hanley says that fewer than one dozen facilities in the United States perform PB antiviral T-cell infusions. Of that selective group, Children’s National is the only U.S. location that also grows the specialized T-cells from naïve CB, a procedure that takes a bit longer to accomplish but can help patients whose blood type is in short supply.

Thirteen patients were infused with PB mCTL, and 12 patients were infused with the T-cells derived from cord blood. Patients received their transfusions from 35 to 384 days after their stem cell or cord blood transplant. Within four weeks, the research team saw up to a 160-fold increase in virus-specific T-cells, a development that coincided with patients’ response to therapy. “The overall … response rate in both groups was 81 percent,” writes Hanley and colleagues.

Eight patients had a complete response. Five had a partial response. Nine remain free of infection/reactivation. What’s more, the patients’ restored immunity was durable with at least one patient remaining free of infection two years after treatment – without the need for pharmaceuticals administered in a hospital setting, which exacts a higher overall cost to the healthcare system.

“This study demonstrates that mCTL derived from the PB of seropositive donors, as well as the CB of virus naïve donors, expand in vivo and are active against multiple viruses. Furthermore, by restoring immunity to multiple viruses simultaneously, the need for continued prophylaxis with pharmacotherapy is eliminated, thus, improving the efficiency and cost-effectiveness of protecting SCT and CBT recipients from these potentially lethal viruses,” Hanley and co-authors conclude.

Related Resources: Research at a Glance

Training t-cells, essential players in the immune system, to fight a trio of viruses

Children's is the only U.S. pediatric hospital that manufactures specialized T-cells from native cord blood

What’s Known
Following treatment, patients with leukemia, lymphoma, and other cancers may receive a transplant in order to restore their body’s natural ability to fight infection and, sometimes, such transplants are a component of leukemia treatment. (Leukemia is the second most common blood cancer, after lymphoma, and its incidence rate has increased by 0.2 percent annually from 2002 to 2011.) A stem cell or cord blood transplant restores the body’s ability to produce infection-fighting white blood cells. After such transplants, however, patients can face heightened risk of developing a life-threatening infection with such viruses as adenovirus, cytomegalovirus, or Epstein-Barr virus.

What’s New
A head-to-head comparison of two strategies to thwart such viral infections shows that both approaches leverage the power of multivirus-specific, donor-derived T-cells (mCTL), which are highly skilled at recognizing foreign invaders. The research team, made up of nine scientists and clinicians affiliated with Children’s National Health System, grew personalized T-cells from peripheral blood (PB) of adult donors who were seropositive for CMV and also coaxed T-cells to grow from naïve cord blood (CB). PB-derived cells have long memories of past battles; naïve CB-derived cells need additional training to acquire such skills. From 35 to 384 days after their stem cell or cord blood transplant, 13 patients were infused with PB mCTL and 12 patients were infused with CB mCTL. Within four weeks, patients experienced up to a 160-fold increase in virus-specific T-cells, which coincided with their response to therapy. Overall response rate was 81 percent.

Questions for Future Research
Q: Could T-cells be personalized to attack other viruses that infect patients post-transplant, such as human parainfluenza virus and BK polyomavirus, providing the potential to target five viruses in a single infusion?
Q: Could the proteins that are used to train T-cells to attack certain viruses also be used to create a personalized approach to tumor suppression?

Source: “A Phase 1 Perspective: Multivirus-Specific T Cells From Both Cord Blood and Bone Marrow Transplant Donors.” Hanley, P., M. D. Keller, M. Martin Manso, C. Martinez, K. Leung, C.R. Cruz, C. Barese, S. McCormack, M. Luo, R.A. Krance, D. Jacobsohn, C. Rooney, H. Heslop, E.J. Shpall, and C. Bollard. Presented during the International Society for Cellular Therapy 2016 Annual Meeting, Singapore. May 26, 2016.