Barriers to Treatment - Developing CD47 Antibody Therapy for Children's Cancer

"A new antibody therapy could dramatically improve outcomes for pediatric tumors."

What This Project Does

  • Kathleen Sakamoto, MD, PhD
  • Shelagh Galligan Professor in the School of Medicine
    Stanford University

A research team at Stanford University led by Drs. Kathleen Sakamoto and Irv Weissman has received a $1.37 million grant from CureSearch titled "Development of CD47 Monoclonal Antibody Therapy for Pediatric Tumors." Drs. Sakamoto and Weissman are developing a Phase I clinical trial for children with relapsed tumors using a new antibody treatment. Phase I clinical trials are the earliest stage of testing a new treatment. In a Phase I trial, researchers test a new treatment on a small group of patients to find out if a drug is safe, what its side effects are, and most importantly, whether it works to treat cancer.

In a healthy person, when the body makes abnormal cells or cells become old, the body's scavenger cells, called macrophages, eliminate them in a process defined as programmed cell removal. When a person has cancer, the abnormal cells are not eliminated by the macrophages. Researchers under the leadership of Dr. Irv Weissman discovered that pediatric brain tumor, leukemia, bone tumor and neuroblastoma cells overproduce a cell surface protein known as CD47. The overproduction of CD47 on cancer cells tells macrophages "don't eat me," allowing the disease to progress. The members of Dr. Weissman's team (Drs. Sam Cheshier, Jens Peter-Volkmer, and Sid Mitra) have successfully tested an antibody to block the "don't eat me signal" in a variety of cancer cells and in animals. The CureSearch grant will support this research team in conducting a Phase I clinical trial at the Lucile Packard Children's Hospital at Stanford University. Their study will test whether anti-CD47 monoclonal antibody will decrease the size of tumors in children, by blocking the CD47 "don't eat me" signal and allowing macrophages to eliminate cancer cells.

Potential Impact on Children

There many types of childhood tumors, but brain tumors are the most common solid tumor in children. The clinical trial developed by Dr. Sakamato and Dr. Weissman will treat children with brain tumors using their novel antibody therapy. In early studies, Dr. Weissman has shown that the antibody treatment is more effective and better tolerated than standard chemotherapy. Because antibody therapy uses the body's own immune system to kill cancer cells, it is easier to tolerate and has fewer side effects than toxic chemotherapies. If the trial is successful, this therapy could be widely used to treat childhood tumors.

Project Updates

6-Month Research Update - June 2014

In previous studies, Dr. Weissman's team has shown that using antibodies that block CD47, the protein present on many cancer cells, have effectively enabled macrophages to "eat" cancer cells, reducing tumor burden. This antibody, called Hu5F9G4, has been shown to be successful in treating several central nervous system tumors in early studies. Their early tests used mice with medulloblastoma. With the anti-CD47 antibody, there was a significant reduction in tumors as soon as two weeks, and by the end of four weeks of treatment, the tumors were virtually eliminated.

Another major benefit was that the mice receiving this antibody did not experience significant side effects typical of chemotherapy treatments. The researchers believe that the antibodies target cancer cells and spare normal cells, so that the immune system gets rid of cancer cells without harming normal cells. In other words, the treatment was very effective and had few side effects. The team recently published an article about these results. Currently, Dr. Weissman's team is completing a Phase I clinical trial in adults that tests the CD47 antibody on adult tumors.

Dr. Weissman's team has tested this antibody on a number of different types of cancer cells, including medulloblastoma, high-grade glioma, rhabdoid tumors, leukemia, and osteosarcoma. The pediatric trial of this antibody therapy, funded in part by CureSearch, will begin as soon as the adult antibody trial has been completed. We are thrilled to support this exciting research and we look forward to sharing the progress of the clinical trial.

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