How Cord Blood Transplants Are Transforming Care for Children with Immunodeficiencies

The role of blood stem cell transplants in treating immunodeficiency disorders has increased dramatically in recent years, and the Cell Therapy and Bone Marrow Transplant Program at Texas Children’s Hospital continues to bring innovative approaches to this lifesaving therapy. Annually, the hospital performs over 140 transplant and cell therapy infusions across both malignant and nonmalignant diagnoses, drawing on a multidisciplinary team of experts. Leading this effort is Caridad Martinez, MD, the program’s chief, who has dedicated her career to improving outcomes for young patients in need of transplant.

Stem cell transplants, which help restore the body’s ability to produce critical infection-fighting cells, have become a cornerstone of Dr. Martinez’s work. She and her team perform transplants to treat immune disorders such as severe combined immunodeficiency (SCID), chronic granulomatous disease (CGD), Wiskott-Aldrich Syndrome (WAS), and primary immune regulatory disorders (PIRDs), among others.

​​​An underutilized cell source
Most blood stem cell transplants today rely on stem cells from the bone marrow or peripheral blood. However, cord blood stem cells collected from the umbilical cord and placenta after a baby is born offer several advantages for certain conditions over other sources. These include wider availability and the ability to achieve outcomes similar to transplants from a full HLA match, even with partially matched cord blood. This unique aspect of cord blood is particularly important for diverse patients, who often face challenges finding a suitable donor match.

“We work with a very diverse patient population here in Houston,” Dr. Martinez said. “Only about 20% of our patients have a matched sibling available, and it’s difficult for them to find an unrelated match donor in the registry. For some patients, for example those with SCID, transplant is needed very quickly after birth.”

Additionally, studies have found that cord blood transplants offer a lower risk of complications, including graft-vs-host disease (GVHD), a common post-transplant condition, a finding replicated in Texas Children’s population.

“Among our patients, we’ve seen lower toxicities, and the vast majority of our patients don’t experience chronic GVHD,” Dr. Martinez said. “It’s rare to see severe complications from infections in these babies, which is a significant achievement for this patient population.”

Pioneering a unique protocol
Texas Children’s has treated nearly 100 immune patients using cord blood transplant, which is now the hospital’s standard approach for some of these diseases. Unlike most institutions, Texas Children’s omits serotherapy from their regimen in an effort to improve delayed T-cell reconstitution. While serotherapy is currently not standard of care for patients with nonmalignant disorders, it’s widely used to reduce the incidence of GVHD.  

Last year, Dr. Martinez and her team published the first prospective single-center study in the Unites States demonstrating that cord blood transplants without serotherapy, in a large group of patients with non-malignant disorders and a very high risk of rejection, provide marked improvement in survival without an increased incidence of GVHD or graft failure. Rather than serotherapy, fludarabine, which is an immunosuppressive agent with a very short half-life, is used to reduce the risk of transplant rejection.

This trial evaluated the two-year overall survival rate, achieving a 91% survival rate, which is comparable to matched transplants for some of these diseases.  

“Our findings showed cord blood transplants are an excellent option for patients who lack a matched sibling,” Dr. Martinez said. “This means we can treat more children—especially those from minority groups who are underrepresented in donor registries—faster and with fewer complications.”  

Current research led by Dr. Martinez is focused on comparing this attractive donor source to other sources in patients treated at Texas Children’s Hospital over about a 20-year period.  

Care over the long term
Beyond acute care, Dr. Martinez is a strong advocate for long-term follow-up for children who have undergone stem cell transplants.  

“Long-term survivorship programs are becoming more common for malignant disease, but we also need survivorship care for nonmalignant disorders,” Dr. Martinez said. “We want to understand how our patients are doing not just immediately after the transplant but as they age. How are they doing in school? How do they compare to their peers? This information is critical. We need a multidisciplinary team to follow these patients longitudinally after transplant.  At Texas Children’s we are blessed to have a combined Immune Disorders and BMT Program that oversees these patients very closely before, during, and after transplant.”

To support this effort, Texas Children’s has developed a Long-Term Survivor BMT Clinic that provides specialized care for transplant recipients as they grow and develop. The clinic’s long-term focus enables Texas Children’s to collect data over years and even decades, offering a more comprehensive picture of transplant outcomes. This view helps identify areas where care can be further improved and gives families a support system that extends well beyond the initial transplant.

“Texas Children’s commitment to comprehensive, patient-centered care is what enables us to achieve these results,” Dr. Martinez said. “Through our specialized clinics and multidisciplinary approach, we’re ensuring that every child receives the most advanced care possible before, during, and after transplant. Our goal is not only to cure these children from their fatal diseases but also importantly ensure close follow up afterwards to help them grow, thrive, and achieve all their dreams.”  

To consult with Texas Children’s Cell Therapy and Bone Marrow Transplant Program or refer patients with primary immunodeficiency disorders or other nonmalignant conditions, Texas Children’s offers an online referral form. For program-related questions, call 832-826-5100.