Researchers reveal genomic characteristics of recurrent medulloblastomas

Lee Han-soo  Published 2018.05.11  16:24  Updated 2018.05.11 16:24

Professors Kim Seung-ki (left) and Professor Phi Ji-hoon

Researchers at Seoul National University Hospital have opened up new therapeutic possibilities as they unveiled the genetic analysis of pediatric brain tumors that frequently recur, the hospital said Wednesday.

Medulloblastoma (MB) is the most common malignant brain tumor in children. Despite significant advances in understanding the molecular pathogenesis and achievement of a high cure rate in medulloblastoma, recurrent medulloblastomas are still dismal.

The research team, led by Professors Kim Seung-ki and Phi Ji-hoon from the department of neurology at the hospital and Professor Park Ae-Kyung from Soon Chun Hyang University Hospital, conducted genetic testing on 17 patients.

The patients had recurrent medulloblastomas after treatments to remove the first medulloblastomas at Seoul National University Children's Hospital, Severance Hospital and Seoul National University Bundang Hospital from 2002 to 2016.

The team found that the frequency of DNA mutations in recurrent tissues was higher when compared to tissues collected from the first medulloblastomas surgery. It also discovered that mutations in cancer-associated genes such as PTEN and MTOR newly emerged.

In particular, some of the relapsed tumors showed a characteristic pattern of gene expression in malignant gliomas, emphasizing the importance of medical staffs distinguishing between recurrent medulloblastomas and malignant gliomas.

Despite advances in therapy, patients with recurrent medulloblastomas have a long-term survival rate of about 70 percent. There is no treatment available for recurrent medulloblastomas.

However, if doctors can distinguish between recurrent medulloblastomas and malignant gliomas, they can open new possibilities for the patients as malignant gliomas are treatable.

In other words, secondary malignant gliomas commonly have PDGFRA gene abnormalities. Therefore, a drug targeting the gene abnormality can treat the illness, the hospital said.

The team stressed that malignant gliomas are also hard to treat, but studies are going on to find a targeted therapy for malignant gliomas making it more hopeful compared to recurrent medulloblastomas.

“This study demonstrated the power of genetic analysis techniques -- generation sequencing -- in the diagnosis of pediatric malignant brain tumors, especially recurrent tumors,” Professor Kim said. “The possibility of targeted therapy will become the basis for introducing precision medicine for diagnosing and treating pediatric brain tumors.”

Acta Neuropathologica published the result of the study.

<© KBR , All rights reserved.>