Clinical and Pathophysiological Investigations Into Erdheim Chester Disease

Rare and potentially lethal, Erdheim-Chester Disease (ECD) is a histiocytic neoplasm about which little is known, and for which there remains a paucity of effective treatments. Histologically, it is categorized as a non-Langerhans cell histiocytosis, and most commonly occurs in men between the ages of 50 and 70, although cases have been reported in women, and rarely, children. Worldwide about 600 cases have been reported, and the disorder remains difficult to diagnose due to its rarity and protean manifestations. The phenotype of ECD ranges from almost asymptomatic patients diagnosed incidentally when imaging studies are done for other reasons, to patients presenting with multiple organ failure who die shortly after diagnosis. These multifarious presentations, and the subsequent response to therapy, have not been well documented and create the need for a prospective study to learn more about this devastating disorder.

Protocol 11-HG-0207, "Clinical and Pathophysiological Investigations into Erdheim-Chester Disease," is a natural history study designed to better understand and describe the natural history, pathophysiology, and response to therapy, of this devastating disorder. We will use a prospective design to enroll and follow qualified men and women, of all ethnic groups, ages 2 to 80 years, who will be screened for candidacy prior to enrollment. If appropriate for the study, patients may opt to be evaluated at the NIH Clinical Center, or may opt to send tissue and records for analysis. The NIH Clinical Center will be the only center for this study, and patients may return for follow-up visits every two to three years, or send copies of test results in lieu of an admission. The enrollment ceiling is 100 patients and we may close the study to new recruitment at that time, but keep the study open to see established patients and to analyze data. Thus, we do not have a definite time-period for the completion of the study.

Through the prospective design, we will collect data from medical histories and physical exams, lab tests, imaging studies, organ-function studies, various measurement tools, and medical consultations. Data will be collated into spreadsheets and divided into functional categories such as organ system complications, to facilitate analysis. We will analyze the data with the assistance of an NIH statistician using parametric and non-parametric methods to assess overall trends in survival, and to look for patterns in organ involvement, patterns in response to various therapeutic regimens, and, lastly, to look for an association between the BRAF V600E mutation and disease severity.

Patient safety and privacy, and respect for the autonomy of the patients, are our top priorities. All patients will be carefully screened prior to participation, and we follow Clinical Center policies regarding informed consent. Data will be stored electronically and in hard copy, in password protected computers and locked cabinets, respectively. Only the PI, the responsible physician, and select AIs, will have access. Patients will be closely monitored during NIH admissions, and the investigators will track all adverse events according to NIH policy. The investigators will keep patients apprised of test results and will reiterate the risks and benefits of procedures during NIH evaluations. Lastly, the investigators will respect patients rights to refuse testing.

We will disseminate the results of our analyses in publications and presentations intended to educate the medical community regarding the diagnosis and management of ECD, and to spur research. We hope our efforts will eventually lead to better outcomes for patients.