Monitoring HHV-6 in CAR T-Cell Therapy: A Prospective Study by Emily Blyth et al.
Emily Blyth, Haematologist, Clinical Lead of the Immune Effector Cell Service at Westmead Hospital, shared a post on LinkedIn:
“In this week’s issue of Blood Journals Portfolio – we performed prospective surveillance of HHV6 in CAR T-cell recipients – HHV-6 viremia occurred in 42% of 86 patients, with two cases of encephalitis, one fatal. This contrasts with earlier reports suggesting HHV-6 reactivation is rare in this setting. Notably, prospective screening identified one encephalitis case early, enabling successful treatment and full recovery.
Why does this matter? Not all CAR T clinical scenarios are equal – different pre-CAR T therapy, products with varied lymphodepletion regimens and toxicity profiles create distinct vulnerability to opportunistic infections.
HHV-6 encephalitis, though uncommon, can mimic or complicate neurotoxicity syndromes, highlighting the importance of keeping infection in mind to ensure appropriate and timely intervention.
Our data suggest that HHV-6 should be considered in patients with atypical or refractory neurotoxicity, and that further research is needed to define risk factors and the role of routine surveillance.
The other important feature is HHV6 viral load in blood is not correlated with tissue infection in the same way as CMV is. To know in advance that HHV6 is around helps a lot when the clinical features of tissue disease become apparent.
What will we be doing with the information we have available today? Weekly monitoring for HHV6 in the first 4 weeks, longer in those with more severe toxicities and more immune suppression. We think our case mix and this data warrants this approach, more research needed for a wider range of disease targets, CAR constructs and application of CAR T at different stages of the treatment journey.”
Title: Human herpesvirus 6 viremia and encephalitis in CAR T-cell recipients
Authors: Stephanie T. Isaac, David C. Bishop, Fahad Shaikh, Kenneth Micklethwaite, David J. Gottlieb, Emily Blyth
Read the full article in this week’s issue of Blood Journals Portfolio.
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