How We Treat Juvenile Myelomonocytic Leukemia (JMML)

Expert Care and Treatment for Childhood Blood Cancers

The Hematologic Malignancy Center at Dana-Farber/Boston Children's Cancer and Blood Disorders Center is one of the top pediatric leukemia and lymphoma treatment centers in the world. In addition to treating blood cancers, our Center also treats histiocytosis, a condition that shares some of the characteristics of cancer.

Childhood Hematologic Malignancy Center

JMML is not easily treated, though several therapies offer hope for a successful outcome. A stem cell transplant is the best option; however, your child's team of doctors will help determine the best approach for your child's unique situation, based on:

  • Your child's age, overall health, and medical history
  • The extent of the disease
  • Your child's tolerance for certain medications, procedures, or therapies
  • How your child's doctors expect the disease to progress
  • Your opinion and preferences

Treatment Options for JMML

Stem Cell (Bone Marrow) Transplant

Stem cells are a specific type of cell from which all blood cells develop. They can grow into red blood cells to carry oxygen, white blood cells to fight disease and infection, and platelets to aid in blood clotting. Stem cells are found primarily in the bone marrow, but some also circulate in the blood stream.

When your child's stem cells are replaced with those of a healthy and compatible donor, it is called allogeneic transplantation. The goal is for healthy stem cells from another person (whose tissue must be the same, or almost the same, as your child's) to restore your child's normal blood production.

All children undergoing a stem cell transplant for JMML must receive high-dose chemotherapy to make room in their bone marrow for the new stem cells. Called a "conditioning regimen" this chemotherapy accomplishes several important things. It suppresses the body's immune system to prevent rejection of the stem cells, and it destroys cancer cells in the body. Like a blood transfusion, stem cells are given to a child through an intravenous (IV) catheter. Children are awake through this painless process.

It generally takes two to four weeks for the stem cells to multiply and make new blood cells. This is called engraftment. Side effects, such as fever, chills, and shortness of breath, can accompany the infusion of stem cells. More significant complications, including graft rejection and graft-versus-host disease (a condition in which the donor's immune cells attack the patient's body), can occur following the transplant.


Chemotherapy is a drug treatment that works by interfering with the cancer cell's ability to grow or reproduce. Standard chemotherapy alone is not adequate for curing JMML but may be used to decrease symptoms while your child is prepared for a stem cell transplant.

Different groups of chemotherapy drugs work in different ways. Your child may receive chemotherapy orally, as a pill to swallow; intramuscularly, as an injection into the muscle or fat tissue; intravenously, as a direct injection into the bloodstream or IV; or intrathecally, as a direct injection into the spinal column through a needle.

While chemotherapy can be quite effective in treating certain cancers, the drugs cannot differentiate normal healthy cells from cancer cells. As a result, there may be adverse side effects during treatment. Being able to anticipate these side effects can help the care team, child, and family prepare (and, in some cases, prevent) these complications from occurring.

Biological Therapy

Biological therapy refers to a wide range of substances that may be able to involve the body's own immune system to fight cancer or lessen harmful side effects of some treatments.

Childhood Cancer Clinical Trials

Find answers to common questions about clinical trials for childhood cancer, including whether or not a clinical trial may be the right choice for your child. Contact us and we can help you navigate your options.

Clinical Trials for Pediatric Patients

Clinical Trials

Scientists at Dana-Farber/Boston Children's are on the front lines of research involving pediatric cancers and blood disorders, including JMML.

Our Stem Cell Transplant Center is one of eight institutions nationwide investigating the use of umbilical cord transplantation as a novel method for preventing graft versus host disease (GvHD), a serious complication that occurs when transplanted cells do not recognize the tissues and organs of the recipient's body and react adversely. The result of this treatment approach, if it continues to be successful, will be that the degree of match between donor and recipient need not be close, increasing the pool of potential donors for each patient. This could also eliminate the need for long-term drug therapy traditionally needed to treat GvHD.

Clinical trials, or research studies evaluating new treatment approaches, are a major offering at Dana-Farber/Boston Children's. Clinical trials are very important for children with hard-to-treat or relapsed conditions.

We connect patients with trials available through collaborative groups such as the Children's Oncology Group (COG) and the Pediatric Oncology Experimental Therapeutics Investigators' Consortium (POETIC). We are the New England Phase I Center of the Children's Oncology Group. If your child has a hard-to-treat cancer, he or she may be eligible for experimental therapies available through these groups or from one of our independent clinical investigators.

Long-Term Outlook for Children Treated for JMML

Despite advances in treatment, JMML remains difficult to cure. Without treatment, the five-year survival rate is low (about 5%).

Stem cell transplantation has proven to be a successful treatment; however, the relapse risk is significant — about 50 percent — following a transplant. If JMML recurs after a stem cell transplant, a second transplant may be an option.

As with any cancer, prognosis and long-term survival varies greatly. Prompt medical attention and aggressive therapy are important for the best prognosis, and continuous follow-up care is essential. New methods are continually being discovered to improve treatment and decrease side effects of the treatment for the disease.

Long-Term Follow-Up

Some children who are treated for JMML and other pediatric cancers can experience significant long-term problems resulting from their treatment. All children who have been treated for cancer require ongoing, specialized care. Through Dana-Farber/Boston Children's pediatric survivorship programs, childhood cancer survivors receive comprehensive follow-up evaluations from their cancer care team. In addition to meeting with their pediatric oncologist, your child may see one of our endocrinologists, cardiologists, neurologists, neuro-psychologists, or integrative therapy specialists. Patient and family education, psychosocial assessment, genetic counseling, reproductive counseling, and opportunities to speak with other childhood cancer survivors are also available.