Human herpesvirus 6 reactivation and disease are infrequent in chimeric antigen receptor T-cell therapy recipients.

ABSTRACT: Human herpesvirus 6B (HHV-6B) reactivation and disease are increasingly reported after chimeric antigen receptor (CAR) T-cell therapy (CARTx). HHV-6 reactivation in the CAR T-cell product was recently reported, raising questions about product and patient management. Because of overlapping manifestations with immune effector cell-associated neurotoxicity syndrome, diagnosing HHV-6B encephalitis is challenging. We provide 2 lines of evidence assessing the incidence and outcomes of HHV-6B after CARTx. First, in a prospective study with weekly HHV-6B testing for up to 12 weeks after infusion, HHV-6B reactivation occurred in 8 of 89 participants; 3 had chromosomally integrated HHV-6 and were excluded, resulting in a cumulative incidence of HHV-6B reactivation of 6% (95% confidence interval [CI], 2.2-12.5). HHV-6B detection was low level (median peak, 435 copies per mL; interquartile range, 164-979) and did not require therapy. Second, we retrospectively analyzed HHV-6B detection in the blood and/or cerebrospinal fluid (CSF) within 12 weeks after infusion in CARTx recipients. Of 626 patients, 24 had symptom-driven plasma testing, with detection in 1. Among 34 patients with CSF HHV-6 testing, 1 patient had possible HHV-6 encephalitis for a cumulative incidence of 0.17% (95% CI, 0.02-0.94), although symptoms improved without treatment. Our data demonstrate that HHV-6B reactivation and disease are infrequent after CARTx. Routine HHV-6 monitoring is not warranted.

Clinical outcomes and frequency of persistent infection among immunosuppressed patients treated with bebtelovimab for COVID-19 infection at an ambulatory cancer center.

BACKGROUND: There are limited data on clinical outcomes associated with the use of bebtelovimab for the treatment of coronavirus disease 2019 (COVID-19) among cancer patients. We aimed to define the clinical characteristics and outcomes among patients receiving bebtelovimab as part of the COVID-19 therapeutics program at our cancer center. METHODS: This is a retrospective cohort study of immunosuppressed adult patients who received bebtelovimab at Fred Hutchinson Cancer Center between March 2022, and November 2022. We reviewed medical records to capture the date of the first positive COVID-19 test, clinical characteristics, outcomes, and follow-up COVID-19 testing for 60 days after the first positive. Persistent infection was defined as a positive test beyond day 30; these patients were reviewed beyond day 60. RESULTS: Among 93 patients who received bebtelovimab, 64 (69%) had hematologic malignancy. Sixty-nine (74%) patients received bebtelovimab within 2 days after diagnosis. Two (2%) patients were hospitalized, none required ICU care, and one patient died on day 52; although it is unknown if death was directly related to COVID-19. Ten (11%) patients had persistent COVID-19 infection; of these, four received additional COVID-19 therapy with either nirmatrelvir/ritonavir or remdesivir, and five out of six patients with sequencing data available had spike protein mutations associated with bebtelovimab resistance. CONCLUSION: A coordinated systems-based approach led to prompt initiation of bebtelovimab within two days of testing positive in most patients. We observed few hospitalizations or deaths. Persistent infection was noted in 11% of patients with four requiring additional therapies, highlighting a need for novel strategies to manage immunosuppressed patients.