51 - a Review of Human Herpesvirus 6 and Central Nervous System Disease in Oncology Patients

Background: Human herpesvirus 6 (HHV-6) infects most of the human population. With immunosuppression it can reactivate and cause clinical syndromes of central nervous system (CNS) dysfunction. Much of the literature describes cases after hematopoietic stem cell transplantation (HSCT), ranging from encephalitis to a defined post-transplant acute limbic encephalitis syndrome (PALE). Outside of HSCT, studies of HHV-6 encephalitis in cancer patients are limited to case reports.

Methods: In this retrospective review, we present data from all patients admitted to MD Anderson Cancer Center between March 2016 and December 2018 that met established definitions for encephalitis, aseptic meningitis or HHV-6 PALE with detectable HHV-6 DNA in the cerebrospinal fluid (CSF) detected using either the Viracor or Biofire® Meningitis Encephalitis (ME) Panel testing platforms and no other identified etiology. We extracted demographic features, known risk factors, imaging findings, CSF analysis, treatments and patient outcomes from medical records.

Results: 725 patients underwent HHV-6 testing during the study timeframe, with 19 (2.6%) cases of HHV-6 mediated CNS disease identified. Most patients, 13/19 (68%), had undergone HSCT. Median time to presentation was 31 days post-transplant. Survival at 240 days after transplant was 62% often with long-term neurologic sequelae. CSF tended to have lymphocyte predominance and nearly all patients had peripheral lymphopenia. Other at risk populations identified included 2/19 (11%) patients who received chimeric antigen receptor (CAR) T-cell therapy, 2/19 (11%) who received biologic immunotherapy, and 2/19 (11%) who had non-HSCT hematologic malignancy. Notable discordance among testing platforms was found in 5/9 (55%) of patients receiving both testing platforms.CSF and Laboratory Analytes
Findings and Outcomes in HSCT Patients
Findings and Outcomes in Non-HSCT Patients


Conclusion: In addition to HSCT patients, HHV-6 reactivation leading to CNS disease also occurs in settings such as following adoptive T cell therapy or biologic immunotherapy. Significant diagnostic discordance exists between testing platforms.