If you, or someone for whom you care has been diagnosed with a glioma, what you need most as you face the challenge is information. The more information with which you can arm yourself, the more educated your decisions can be. The purpose of this webpage is to give you information on the DecisionDx-LGG test to discuss with your physician.
What is DecisionDx-LGG?
We believe the best way to approach a treatment plan begins with information gathering, followed by collaborative decision making. Fortunately, today there is a way for a physician to know, based on the molecular profile of a patient's specific tumor, the likely behavior of the tumor.
Historically, gliomas have been diagnosed and graded using traditional histopathology techniques. This means that a pathologist stains a sample of the glioma specimen that was obtained from surgery and reviews it under a microscope. The pathologist will then grade the tumor as grade 2, 3, or 4 based upon criteria established by the World Health Organization (WHO) classification system. This WHO grade provides an indication of prognosis of the glioma. Your physician will then use this information in your treatment planning.
However, there is an issue in relying solely upon the histopathology diagnosis for individual treatment planning. The issue relates to a) the subjectivity of the WHO classification system, b) the limited tumor tissue that can be reviewed under the microscope, and c) the fact that reviewing a stained slide of a glioma does not provide information about the biology of the tumor.
Grade of glioma establishes prognosis and treatment planning. Because there may be variability in the way different pathologists grade the same slide, there is risk of over- or under-treatment of an individual patient's tumor. For example, patients with a grade 3 tumor may be diagnosed with a grade 2 tumor. This difference would result in under-treatment for that patient. Likewise, a patient with a grade 3 tumor who is diagnosed as grade 4 would likely be over-treated. For these reasons, it is helpful to have objective information on tumor biology (DecisionDx-LGG) that is not subjective and does not vary.
The DecisionDx-LGG is a robust, proprietary multi-methylation assay that determines the glioma-CpG island methylator phenotype (G-CIMP) of grade 2, 3 or 4 gliomas. This molecular profile called the CIMP profile, is expressed as a CIMP+ or CIMP- phenotype. Patients with a CIMP+ glioma show a more favorable prognosis. This favorable prognosis cannot be detected with histopathology alone. The DecisionDx-LGG CIMP profile is an independent predictor of survival, even after adjustment for grade and age.
The DecisionDx-LGG CIMP phenotype, in addition to factors such as age and grade provide more accurate data on expected prognosis for optimal individual treatment planning.
The DecisionDx-LGG test is run from a sample of tumor that was taken during surgery. There is no extra procedure or sample collection required. When your doctor orders the test, the appropriate sample will be requested from the lab where it is stored and sent to Castle Biosciences, Inc. for testing. A report will be generated and provided back to your doctor. This process takes approximately 2-3 weeks.
The DecisionDx-LGG test analyzes 9 genetic areas of the tumor for their methylation status. The methylation status of each of these 9 areas are then applied to a mathematical formula or algorithm and a CIMP+ (meaning methylated) or CIMP- (meaning unmethylated) phenotype is determined.
How was DecisionDx-LGG developed?
Discovery
Researchers at M. D. Anderson Cancer Center in Houston Texas studied glioma tumor tissue and survival outcomes from 272 patients. The test for CIMP+ and CIMP- was developed from this study.
Development
The researchers then conducted a separate study on a group of over 380 glioma tumor samples. This study, the validation study, confirmed that the test could determine the CIMP+ and CIMP- phenotype status of the glioma tumors.
Validation
Castle Biosciences subsequently completed a clinical validation study to ensure that its test procedures would result in similar CIMP phenotype status at its laboratory.
How is DecisionDx-LGG paid for?
Castle Biosciences, Inc. will be working with Medicare, commercial insurance providers and, in some cases, your physician's institution to secure payment coverage for DecisionDx-LGG. Claims will be submitted on patient's behalf and followed through the system to payment. The Castle Patient Assistance Program is in place to help manage balances due and to provide assistance in cases of financial hardship.