Teen with refractory ITP achieves remission after stem cell transplant

A donor stem cell transplant and follow-up treatments helped a teenage girl achieve long-term remission from refractory immune thrombocytopenia (ITP), according to a case report.

The girl’s ITP was refractory, meaning it didn’t respond to standard first- and second-line treatments. After several life-threatening complications, the clinical team initiated an allogeneic hematopoietic stem cell transplant (HSCT), which uses donor stem cells to rebuild a patient’s blood and immune system. While the girl continued to experience challenges, by seven years after the transplant, she remained in remission with normal platelet counts and no signs of active graft-versus-host disease.

“This case highlights that HSCT, while rarely employed for ITP, can offer long-term disease control in select patients with severe, refractory disease,” the researchers wrote.

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The study, “Allogenic Hematopoietic Stem Cell Transplant for Refractory Immune Thrombocytopenia,” was published in Pediatric Transplantation.

ITP is an autoimmune condition in which misdirected immune activity destroys platelets, which are blood cell fragments important for clotting. Resulting symptoms can include external and internal bleeding.

There are several treatment options for ITP, including corticosteroids and intravenous immunoglobulin (IVIG). Corticosteroids are powerful anti-inflammatory and immune-suppressing medications, while IVIG involves infusing a mixture of antibodies from healthy donors.

Doctors may consider a case refractory if it fails to respond to these first-line treatments as well as more aggressive therapies. “Refractory ITP, while rare, presents treatment challenges and can incur significant complications and treatment-related toxicities,” the researchers wrote.

In severe cases, clinicians may explore alternative treatments, such as allogeneic HSCT. This procedure replaces a patient’s blood-forming stem cells with donor stem cells. If successful, it may allow donor-derived blood and immune cells to take over and support platelet recovery.

In the present case, the team describes a girl with severe, refractory ITP who underwent HSCT.

Years of severe bleeding led to transplant decision

The girl received an ITP diagnosis after presenting with fainting and excessive menstrual bleeding at age 10. Although she initially responded to IVIG and corticosteroids, her platelet counts dropped again after eight months of treatment.

Over the following years, despite a variety of treatment approaches, she continued to experience ITP symptoms and complications. These included two brain bleeds, or intracranial hemorrhages, which can be life-threatening.

After continued failure to respond to treatment, the clinical team discussed HSCT with the patient and her mother. Together, they decided to proceed with the transplant. “The patient herself, who had previously declared her birthday wish to be a normal platelet level, stated her goal was to avoid weekly transfusions and infusions,” the researchers wrote.

Testing revealed that the girl’s sister was a donor match, enabling HSCT. Before the procedure, the girl received several medications designed to prevent complications such as severe mucositis, or painful inflammation of the digestive tract lining, and infections. She also received preventive treatment for graft-versus-host disease (GVHD), a condition in which the donated cells attack the recipient’s cells.

Engraftment was achieved, meaning the donor cells began producing new blood cells, although the girl continued to receive blood transfusions and IVIG as needed. “She was able to discharge after approximately 1 month in the hospital and continued with close monitoring as an outpatient,” the team wrote.

Four weeks after the procedure, the doctors ran blood tests to determine chimerism, or how many of the patient’s blood cells came from donor cells rather than her own cells. They found that 100% of CD33 myeloid cells, a group of blood cells that includes infection-fighting white blood cells, had characteristics consistent with the donor. They also found that 65% of CD3 T-cells had characteristics consistent with the donor, meaning T-cell chimerism was mixed.

In the first six months after transplant, the girl developed viral and bacterial infections that required treatment. However, her platelet counts remained stable, and testing continued to show a mix of donor and patient T-cells.

Donor cell infusion helps restore remission

Two years after the HSCT, the ITP symptoms re-emerged. The clinical team suspected the relapse was T-cell mediated, based in part on mixed T-cell chimerism, in which some T-cells still showed signs consistent with the patient’s original immune system rather than the donor’s. Despite treatment with a T-cell-targeting immunosuppressant, the proportion of T-cells not from the donor later rose from about 35% to 50%.

To address this, the clinicians recommended a donor lymphocyte infusion, or DLI. This procedure involves administering white blood cells from the original stem cell donor to try to boost donor T-cell levels. “The donor was again the patient’s sister and the infusion was well-tolerated,” the team noted.

After the DLI, chimerism tests indicated that donor cells had fully taken over the measured T-cells and myeloid cells. The patient’s platelet count initially fell sharply, but then recovered and remained above 100,000 per cubic millimeter. She also developed GVHD, a transplant-related complication that required treatment.

By the time this study was published, it had been approximately seven years since the HSCT and 5.5 years since the DLI. The girl still had a normal platelet count and had no signs of active GVHD.

The complicated clinical course after HSCT in this case indicates potential risks of the procedure. However, the eventual success of the treatment supports considering HSCT for select people with refractory ITP who have failed other therapies, according to the team. “While HSCT is a high-risk therapy and is rarely employed in the treatment of ITP, it should be considered for those with refractory disease who have failed other therapies,” they wrote.