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Eugene Hwang

Unexpected heterogeneity in CNS-PNET patients treated as a single entity

Eugene Hwang

“We found that some patients diagnosed with standard tools underwent much more treatment than necessary or intended,” said Eugene Hwang, M.D.

Eugene I. Hwang, M.D., a neuro-oncologist in the Center for Cancer and Blood Disorders, and other researchers at Children’s National Health System, Seattle Children’s Hospital and Research Institute, the Fred Hutchinson Cancer Research Center and the Hopp-Children’s Cancer Center at the NCT Heidelberg recently published the results of a clinical trial focusing on children with histologically diagnosed supratentorial primitive neuroectodermal tumors (CNS-PNET) and pineblastomas (PBLs).

The clinical trial, published online October 17, 2018 in the Journal of Clinical Oncology, included children and adolescents aged 3-22 with these brain cancers who were randomly assigned to receive carboplatin during radiation and/or isotretinoin after the standard intensive therapy (high-dose craniospinal radiation and months of inpatient chemotherapy).  Importantly, because each patient was treated prospectively according to the clinical trial design, the conclusions related to tumor biology were felt to be less affected by varied treatment plans.

“This trial really highlighted the importance of new molecular testing methods in accurately diagnosing some of the brain cancers included in the trial. We found that some patients diagnosed with standard tools underwent much more treatment than necessary or intended.” says Dr. Hwang. “Kids who aren’t receiving the right form of cancer treatment may not get better despite months and months of intensive treatment.”

During this clinical trial, 85 participants with institutionally-diagnosed CNS-PNETs/PBLs were enrolled. Out of the 60 patients with sufficient tissue, 31 were non-pineal in location, 22 of which represented tumors that did not fit in the diagnoses intended for trial inclusion.

The researchers discovered that patient outcomes across each molecularly-diagnosed tumor type were strikingly different. Patients with molecularly-confirmed supratentorial embryonal tumors/PBLs exhibited a five-year event free survival (EFS) and an overall survival rate of 62 percent and 78.5 percent, respectively. However, patients with molecularly-classified high-grade gliomas (HGGs) had a five-year EFS of 5.6 percent and OS of 12 percent, showing no benefit even with the chemotherapy and craniospinal radiation.

Researchers determined that for patients with CNS-PNETs/PBLs, prognosis is considerably better than previously assumed when molecularly-confirmed HGG are removed. Dr. Hwang and co-authors concluded that molecular diagnosis can greatly aid standard pathological diagnostic tools, preventing unnecessary intensive therapy for some patients while enabling more rational treatment for others.

“The findings from our clinical trial have highlighted the immense challenges of histology-based diagnosis for some types of pediatric brain tumors, and the enormous importance this has for children with brain cancer,” Dr. Hwang says. “We hope that ultimately our study will pave the way for molecular profiling to become a standard component of initial diagnosis.”

Yuan Zhu

The brain tumor field moves forward with new findings and a research grant

Yuan Zhu

Yuan Zhu, Ph.D., and other experts completed new research findings evaluating the effects of manipulating the growth-promoting signaling pathways in brain tumors associated with adults and children.

This month, experts at Children’s National Health System made great strides in brain tumor research, specifically in gliomas, glioblastomas and medulloblastomas. Led by Yuan Zhu, Ph.D., the scientific director and Gilbert Endowed Professor of the Gilbert Family Neurofibromatosis Institute and Center for Cancer and Immunology Research at Children’s National, the team completed new research findings evaluating the effects of manipulating the growth-promoting signaling pathways in brain tumors associated with adults and children. Dr. Zhu’s research was recently published in Cell Reports and he was also awarded a U.S. Department of Defense (DoD) grant to gain a better understanding of how low-grade gliomas form. Together, this work moves the needle on developing more effective treatments for these debilitating and life-threatening tumors.

The study

In his recently published paper, Dr. Zhu and his colleagues, including Drs. Seckin Akgul and Yinghua Li, studied glioblastomas, the most common brain tumor in adults, and medulloblastomas, the most common brain tumor found in children, in genetically engineered experimental models. Dr. Zhu found that when they removed the p53 gene (the most commonly mutated tumor suppressor gene in human cancers) in the experimental model’s brain, most developed malignant gliomas and glioblastomas, while Sonic Hedgehog (SHH)-subtype (SHH) medulloblastomas were also observed. They further suppressed the Rictor/mTorc2 molecular pathway that is known in the regulation of tumor growth. This action greatly reduced the incidence of malignant gliomas and extended the survival of the models, validating the concept that Rictor/mTorc2 could be a viable drug target for this lethal brain cancer in adults.

The study also found that the same Rictor/mTorc2 molecular pathway serves the opposite function in SHH medulloblastoma formation, acting as a tumor suppressor. Findings suggest that if the same drug treatment is used for treating SHH medulloblastoma in children, it could potentially have an adverse effect and promote growth of the tumors.

Ultimately, the study demonstrates that Rictor/mTORC2 has opposing functions in glioblastomas in adults and SHH medulloblastomas in children. While drug therapies targeting Rictor/mTORC2 may be successful in adults, the findings reveal the risks of treating children with pediatric brain tumors when using the same therapies.

The grant

Continuing the study of brain tumors, Dr. Zhu recently received a $575,000 grant from DoD to research benign gliomas, with the hope of gaining a greater understanding of how the tumors form. Low-grade gliomas, or benign brain tumors, are the most common brain tumors in children. While not lethal like their high-grade counterpart, these tumors can lead to significant neurological defects, permanently impacting a child’s quality of life. Most commonly, the tumor can impair vision, often leading to blindness.

Since the tumors only occur in children under the age of eight, Dr. Zhu believes they are linked to neural stem or progenitor cells that exist in the optic nerve only during development, or when children are under eight-years-old. To test if his hypothesis is correct, Dr. Zhu will develop a preclinical model that mimics human brain tumors to study the development of the optic nerve. If his theory proves correct, Dr. Zhu’s long-term goal is to develop a strategy that prevents the tumor formation from ever occurring, ultimately preventing vision loss in children. The grant begins in July and will run for three years.

 

Brian Rood

Improving the understanding of medulloblastoma

Brian Rood

Brian Rood, M.D., employed quantitative proteomics to tumor samples that led to novel therapeutic targets for Medulloblastoma and other tumors.

In a recently published study, Brian Rood, M.D., a neuro-oncologist at Children’s National Health System, employed quantitative proteomics to tumor samples, a technique that could lead to novel therapeutic targets for medulloblastoma and other tumors in the future.

Currently, many experts use genomic characterization to understand the genetic makeup of cancer cells, which has deepened the field’s collective knowledge of tumor biology. However, it has remained challenging to infer specific information about how the tumors will respond and consequently develop more effective therapies. Medulloblastoma is the most common pediatric, malignant brain tumor. Through Dr. Rood’s research using proteomic analysis, he was able to identify and measure the protein makeup of medulloblastoma, which led to a potential pathway for clinical intervention to treat this life-threatening cancer. The findings were published online June 7, 2018, in Acta Neuropathologica Communications.

“The goal of this research was to find out how these tumor cells function at the protein level, which may ultimately help the field identify drug therapies to stop them,” says Dr. Rood. “The genes of a cancer cell are like a blueprint for a building, but the blueprints aren’t always followed in a cancer cell: Not every active gene will produce its corresponding protein. Proteins do the work of the cell, and understanding them will provide a better overall understanding of a cancer cell’s biology.”

Dr. Rood compared proteomic and genomic data to confirm that genetics do not accurately predict the quantity of proteins. By directly quantitating the proteins and comparing them between different subgroups of the disease, they were able to identify protein-based pathways driving tumor biology. With this information, Dr. Rood was able to demonstrate that medulloblastoma depends on a crucial pathway, the eukaryotic initiation factor 4F protein synthesis pathway, resulting in the identification of a potential target for new treatments in medulloblastoma.

Ultimately, Dr. Rood found that proteomic analysis complements genomic characterization and the two can be used together to create a more complete understanding of tumor biology. Going forward, he hopes proteomic analysis will become common practice for studying all tumors, allowing tumors to be categorized and grouped together by protein makeup to help the field identify more effective therapies for all tumors.