Burden of adenoviraemia predicts survival in paediatric recipients of allogeneic haematopoietic stem cell transplant.

BACKGROUND: Adenoviraemia occurs in 15 to 30% of paediatric allogeneic haematopoietic stem cell transplant (HSCT) recipients, and is a significant cause of morbidity and mortality which lacks satisfactory therapeutic options. The relationship between burden of adenovirus and mortality is poorly defined in this patient group. OBJECTIVES: To determine the relationship between adenoviraemia and mortality in paediatric HSCT recipients. STUDY DESIGN: A retrospective review of blood adenovirus PCR results in paediatric HSCT recipients spanning February 2003 to September 2016 was conducted. Three measures of adenovirus burden were defined; number of days with significant viraemia, peak adenovirus load and Area under the Curve and related to outcome post-HSCT. RESULTS: A total of 62 patients with episodes of positive blood adenovirus PCR were identified for analysis. Adenoviraemia of more than 7 days, peak viral load of >8000 copies/ml and higher 16 week Area under the Curve were all significantly associated with higher non-relapse mortality in paediatric HSCT recipients. CONCLUSIONS: This retrospective analysis highlights the important predictive value of adenoviral load for non-relapse mortality in young allogeneic HSCT recipients. These data also suggest a possible role for use of these measures as end points in trials of novel adenoviral therapies.

Immune cytopenia post-cord transplant in Hurler syndrome is a forme fruste of graft rejection.

Umbilical cord blood (UCB) is the preferred donor cell source for children with Hurler syndrome undergoing transplant, and its use has been associated with improved "engrafted survival" rates. However, as in other pediatric recipients of UCB transplants for nonmalignant disease, immune-mediated cytopenia (IMC) is a significant complication. This article describes 8 episodes of IMC in 36 patients with Hurler syndrome undergoing UCB transplant. The incidence of IMC was increased in those with a higher preconditioning absolute lymphocyte count and in those conditioned with fludarabine-containing regimens rather than cyclophosphamide, and it included red cell alloantibodies directed at cord blood group antigens that are novel to the recipient. In several cases, IMC was a precursor to immune-mediated complete graft rejection. We describe IMC as part of a spectrum of graft rejection by a residual competent host immune system and a forme fruste of complete graft rejection.

Molecular monitoring of adenovirus reactivation in faeces after haematopoietic stem-cell transplantation to predict systemic infection: a retrospective cohort study.

BACKGROUND: Faecal shedding of adenovirus following allogeneic haematopoietic stem-cell transplantation (HSCT) is an early sign of loss of immune control over adenovirus, but there is no consensus on the role of monitoring of faecal adenoviral load by serial testing. We investigated whether serial faecal PCR monitoring could predict the risk of adenoviraemia and survival outcomes after HSCT. METHODS: We did a retrospective cohort study at the Royal Manchester Children's Hospital, Manchester, UK, of patients who had received their first allogeneic HSCT between Feb 1, 2003, and Sept 1, 2016, and adenovirus infection recorded in their medical records. We excluded patients who had received second or third transplants or autologous HSCT transplants. We obtained characteristics of patients and transplants, including mortality and adenoviral reactivation, from medical records and the hospital database. All patients had blood samples tested weekly for adenovirus by PCR until immunosuppression was stopped and CD3 T-cell count recovered to greater than 0·3 × 109/L. Faecal PCR was done before transplantation in all patients, and after transplantation in patients who had diarrhoea, at the onset of symptoms and weekly thereafter until diarrhoea resolved. We analysed all samples available before and after HSCT. We did subgroup analyses for patients undergoing HSCT for cancer versus non-malignant conditions. We also assessed whether 5 log10 copies per g faeces was a suitable predictive threshold for adenoviraemia. FINDINGS: We included 341 patients who had undergone a first allogeneic HSCT (median age 4·6 years, IQR 1·5-8·0, range 0-20·0). After HSCT, PCR was done in 4116 faecal samples from 293 (86%) patients who had diarrhoea and in 10 649 blood samples from 341 patients. Follow-up ended on July 14, 2017. 173 (59%) of 293 patients had adenovirus in faecal samples and 63 (18%) of 341 had adenovirus in blood samples. Maximum faecal viral load before adenoviraemia correlated significantly with maximum blood viral load (r=0·51, 95% CI 0·38-0·61, p<0·0001). Faecal adenoviral viral load greater than 5 log10 copies per g faeces was predictive of adenoviraemia (odds ratio 10·2, 95% CI 4·9-21·6, p<0·0001) with sensitivity 75·9% and specificity 74·8%. These values were increased further in patients with cancer, to 86·4% and 87·5%, respectively. Among the 28 patients who had positive faecal and blood samples and who had undergone serial faecal PCR monitoring after HSCT, the median time between reaching the faecal viral load threshold and onset of adenoviraemia was 8·0 days (IQR 2·3-21·8, 95% CI 4·0-16·0). Non-relapse mortality was not associated with adenovirus reactivation in faeces alone (9·2%, 95% CI 5·4-14·3 in patients without reactivation vs 7·8%, 3·8-13·7 in those with positive faeces only), but was significantly increased in patients who developed adenoviraemia (27·0%, 95% CI 16·7-38·4, p<0·0001). INTERPRETATION: We identified a threshold faecal viral load that can predict the risk of adenoviraemia. Our findings support proliferation of adenovirus in the gastrointestinal tract before viraemia develops. Faecal PCR is suitable for early detection of children and young adults at risk of adenoviraemia, and its use might help reduce non-relapse mortality in allogeneic HSCT recipients. FUNDING: None.