The bond between siblings is often special. But the bond of two young siblings from Baltimore, Seth and Leilah Washington, has become even more meaningful — Leilah helped her brother Seth beat cancer.
In 2023, at 5 years old, Seth Washington came down with strep throat, but it never seemed to go away. He then started complaining of joint pain to the point that he couldn't walk. His pediatrician ordered a blood test that showed heartbreaking results for Seth's family — he may have cancer. Testing at a local hospital confirmed the unfortunate news. Seth was diagnosed with myelodysplastic syndrome (MDS).
September is Childhood Cancer Awareness Month: Nearly 15,000 children and adolescents in the U.S. were estimated to have been diagnosed with cancer in 2024. MDS, Seth's diagnosis, occurs when the blood-forming cells in the bone marrow become abnormal, leaving the marrow unable to make enough healthy new blood cells. This, in turn, causes low levels of one or more types of blood cells. MDS is rare in children — most cases are in adults over age 50.
Seth and his family turned to Johns Hopkins Children's Center for his care. Doctors told his family that the best treatment for his condition would be a stem cell transplant to replace his damaged blood cells with healthy stem cells that could then repopulate his bone marrow and mature into healthy blood cells. The transplant requires testing for human leukocyte antigen expression on the patient and donor cells, to ensure that there is at least a partial match present.
The Washington family tested to see who might be a match with Seth. "There were no donors in the national marrow donor registry who could match Seth," his mom, Lynette, recalls. His 10-year-old sister, Leilah, "was a 100% match, and she decided she wanted to do it."
To donate stem cells, Leilah received a growth factor injection each day for five days to cause her body to increase the population of stem cells that then traveled to her bloodstream from her bone marrow. On the fifth day, doctors inserted a temporary IV line into her neck for the stem cell collection, which took four to six hours. Seth proudly watched his sister.
The week before the transplant, Seth, who remained in the hospital, started getting chemotherapy to destroy unhealthy bone marrow and prepare his body for new cells. Then, on the day of the procedure, Leilah was able to watch as her healthy stem cells were transfused into Seth's body. Watching the procedures "allowed my children to understand the science," Lynette says.
After the transplant, Seth was on multiple immunosuppressive medications to prevent Leilah's cells from attacking his body, and he also had a feeding tube. Shortly after, Seth's platelets and white blood cells started returning.
During Seth's time at the hospital, Lynette says doctors were always available for questions and helped mark milestones in Seth's treatment. "They celebrated when his blood count came up," Lynette says. She adds that there were also always activities for Seth to do during his hospital stay — whether riding bikes around the unit or playing in the playroom. Seth was able to leave the hospital after more than five weeks.
Now, two years later, at 8 years old, Seth loves dinosaurs, riding his bike and playing drums — among other activities. His MDS is fully in remission. Lynette says the blood inside of Seth is now that of his sister, and his stem cells are 100% hers.
"Now, it's been two years since his treatment. Each time we have checked, the blood cells in Seth originated from his sister — it's incredible!" says Challice Bonifant, M.D., Ph.D., Seth's pediatric oncologist at the Children's Center and Johns Hopkins Kimmel Cancer Center. "He's healthy again and can live a full life thanks to his big sister, Leilah, his whole family, and all their friends who supported them on this journey."
