Viremic co-infections in children with allogeneic haematopoietic stem cell transplantation are predominated by human polyomaviruses

Diagnostic performance and clinical impacts of metagenomic sequencing after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Metagenomic Next-Generation Sequencing (mNGS) is a rapid, non-culture-based, high-throughput technique for pathogen diagnosis. Despite its numerous advantages, only a few studies have investigated its use in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

We conducted a retrospective analysis of 404 mNGS tests performed on 264 patients after allo-HSCT. The tests were divided into three groups (Phase A, B, C) based on the time spent hospitalized post-transplantation, and we evaluated the analytical performance of mNGS in comparison with conventional microbiological tests (CMT), while also analyzing its clinical utility for clinical impacts.

RESULTS

Metagenomic sequencing demonstrated a significantly higher rate of positive microbiological findings as compared to CMT (334/404 (82.7 %) vs. 159/404 (39.4 %), respectively, P < 0.001). The detection rates by both mNGS and CMT varied across the three-phase (mNGS: A-60/89 (67.4 %), B-147/158 (93.0 %), C-125/157 (79.6 %), respectively, P < 0.001; CMT: A-21/89 (23.6 %), B-79/158 (50.0 %), C-59/157 (37.6 %), respectively, P < 0.001). The infection sites and types of pathogens were also different across the three phases. Compared to non-GVHD cases, mNGS detected more Aspergillus spp. and Mucorales in GVHD patients (Aspergillus: 12/102 (11.8 %) vs. 8/158 (5.1 %), respectively, P = 0.048; Mucorales: 6/102 (5.9 %) vs. 2/158 (1.3 %), respectively, P = 0.035). Forty-five (181/404) percent of mNGS tests yielded a positive impact on the clinical diagnosis, while 24.3 % (98/404) of tests benefited the patients in antimicrobial treatment.

CONCLUSION

mNGS is an indispensable diagnostic tool in identifying pathogens and optimizing antibiotic therapy for hematological patients receiving allo-HSCT.

Viral infections in pediatric brain tumor patients treated with targeted therapies

BACKGROUND

Brain tumors are the most common solid malignancies and the leading cause of cancer-related mortality in children. While numerous studies report on viral infections in children with hematologic malignancies and solid organ transplantation, epidemiologic data on the incidence and outcome of viral infections in pediatric patients with brain tumors treated with targeted therapies are still lacking.

OBJECTIVES/STUDY DESIGN

We retrospectively reviewed all children with brain tumors receiving targeted therapies in a primary or recurrent setting at the Medical University of Vienna from 2006 to 2021. Demographic variables, quantitative and qualitative parameters of possible infections, and treatment outcomes were recorded.

RESULTS

In our cohort (n = 117), 36% of the patients developed at least one PCR-proven viral infection. Respiratory and gastrointestinal tract infections were most common, with 31% and 25%, respectively. Central nervous system (CNS) infections occurred in approximately 10%, with an almost equal distribution of varicella-zoster virus, John Cunningham virus (JCV), and enterovirus. Two patients tested PCR-positive for SARS-CoV-2 infection, with one virus-related death caused by a SARS-CoV-2-related acute respiratory distress syndrome. Patients receiving bevacizumab or mTOR inhibitors seem to have a greater susceptibility to viral infections.

CONCLUSION

Pediatric patients with brain tumors receiving targeted therapies have a higher risk of viral infections when compared to children receiving conventional chemotherapy or the general population, and life-threatening infections can occur. Fast detection and upfront treatment are paramount to prevent life-threatening infections in immunocompromised children suffering from brain tumors receiving targeted therapies.

Risk factors and outcome of concurrent and sequential multiviral cytomegalovirus, Epstein-Barr virus, BK virus, adenovirus and other viral reactivations in transplantation

PURPOSE OF REVIEW

Reactivation of viral infections occurs frequently in immunosuppressed populations, particularly in solid organ (SOT) or allogeneic haematopoietic cell (HCT) transplant patients. Concurrent and sequential multivirus infections are common, yet risk factors and outcomes remain unclear. This review aims to identify the patients vulnerable to multivirus infections and characterize the impact of increased viral burden to formulate prevention and treatment strategies.

RECENT FINDINGS

Incidences of up to 89% in SOT and 36% in HCT have been reported for two viruses, and 32% in SOT and 28% in HCT for at least three viruses. Risk factors appear related to an increased burden of immunosuppression, with most viral coinfections occurring within 12 months of transplantation. Direct viral complications such as cytomegalovirus disease are more frequent in coinfected patients, with documented prolonged duration of viraemia, higher viral load and increased end-organ disease. Graft dysfunction, acute rejection and graft-vs.-host disease (GVHD) have also been associated. Increased mortality is reported in the HCT population.

SUMMARY

Multivirus infections occur in a significant proportion of transplant patients and is linked to immunosuppressive burden. There is increasing evidence that this leads to worse graft and patient outcomes. Further prospective studies are required to further comprehensively characterise viral epidemiology, mechanisms and treatment strategies to ameliorate this risk.

Scheduled administration of virus-specific T cells for viral prophylaxis after pediatric allogeneic stem cell transplant

Infections with double-stranded DNA viruses are a significant cause of morbidity and mortality in pediatric patients following allogeneic hematopoietic stem cell transplantation (HSCT). Virus-specific T-cell therapies (VSTs) have been shown to be an effective treatment for infections with adenovirus, BK virus, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). To date, prophylactic regimens to prevent or mitigate these infections using conventional antiviral medications provide suboptimal response rates. Here we report on a clinical trial (NCT03883906) performed to assess the feasibility of rapid manufacturing and early infusion of quadrivalent VSTs generated from stem cell donors ("donor-derived VSTs") into allogeneic HSCT recipients with minimal or absent viremia. Patients were eligible to receive scheduled VSTs as early as 21 days after stem cell infusion. Twenty-three patients received scheduled VSTs. Twenty of 23 patients had no viremia at the time of infusion, while 3 patients had very low-level BK viremia. Two developed clinically significant graft-versus-host disease (GVHD), although this incidence was not outside of expected incidence early after HSCT, and both were successfully treated with systemic corticosteroids (n = 2). Five patients were deemed treatment failures. Three developed subsequent significant viremia/viral disease (n = 3). Eighteen patients did not fail treatment, 7 of whom did not develop any viremia, while 11 developed low-level, self-limited viremia that resolved without further intervention. No infusion reactions occurred. In conclusion, scheduled VSTs appear to be safe and potentially effective at limiting serious complications from viral infections after allogeneic transplantation. A randomized study comparing this scheduled approach to the use of VSTs to treat active viremia is ongoing.

Incidence of BKV in the urine and blood samples of pediatric patients undergoing HSCT

The aims were to investigate the incidence of BKV infection and the presence of HC in pediatric patients undergoing HSCT. Twenty-four children patients (M/F: 17/7) undergoing HSCT in a single center over a period of 1 year were included in the study. The presence of BKV DNA was determined by quantitative real-time PCR in plasma and urine samples at the following times: before transplantation, twice a week until engraftment time, and weekly for + 100 days. The mean age of the patients was 7.79 ± 5.03 years, the mean follow-up time was 95.6 ± 25.9 days, and the average number of samples per patient was 15.8 ± 3.2. BKV DNA was detected in at least one urine sample in 91.6% (n: 22) and at least one plasma sample in 75% (n:18) of the patients. The median time to the first BKV DNA positivity in urine and plasma samples was 11 (range: 1-80) and 32 days (range: 2-79), respectively. The median value of BKV DNA copies in urine and plasma were 1.7 × 10⁶ (range: 2.8 × 10¹ -1.2 × 10¹⁴ ) and 1.9 × 10³ copies/mL (range: 3-2.1 × 10⁶ ), respectively. Thirteen patients (54.2%) had hematuria with BKV viruria; 8 (33.3%) patients had viremia. The median value of the BKV DNA copies in urine and plasma was 4.4 × 10⁷ (range: 65-1 × 10¹¹ ) and 2.9 × 10³ (range: 7-7.8 × 10⁴ ) copies/mL in these patients. Two (15.4%) of the 13 patients with BKV viruria and hematuria were diagnosed with BKV-related HC. BKV DNA viral load monitoring of urine and plasma in pediatric HSCT patients with a high risk for viral infections is valuable for understanding the development of BKV-related HC.

Viral infections and immune reconstitution interaction after pediatric allogenic hematopoietic stem cell transplantation

Background: Viral infections are a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Although immune suppression plays a central role, the literature shows conflicting results on interplay between post-transplant immune reconstitution (IR) and viral infections. Methods: We prospectively studied viral infections and IR in 30 pediatric patients undergoing allogenic HSCT, with a follow-up time of 24 months. In total, 1337 blood (CMV, EBV, HHV-6, ADV and BKV) and urine (BKV and JCV) virus samples were analyzed. IR including B-cells (CD19+), T cells (CD3+, CD4+, CD8+) and NK-cells were measured. Clinical outcomes included overall survival (OS), non-relapse mortality (NRM), graft-versus-host disease (GVHD) and occurrence of blood culture positive bacterial infections. Results: We found BKV reactivation to be most frequent, 47% of the children had viremia and 77% viruria. The frequencies of CMV, HHV-6 and adeno viremia were 37%, 37% and 6%, respectively. Viremias beyond 3 months post-HSCT were uncommon. Factors such as GVHD, use of steroids, EBV and CMV infections and pre-transplant irradiation affected IR. No specific viral infection or IR related factor was associated to OS or NRM. Conclusions: Viral infections and IR interact in a bi-directional manner. Accordingly, close follow-up of both IR and viral loads is warranted.

Incidence of infections after therapy completion in children with acute lymphoblastic leukemia or acute myeloid leukemia: a systematic review of the literature

Infections are a common complication of treatment for pediatric acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). Less is known about infections occurring after treatment. We performed a systematic review of the literature to assess the incidence of infections after therapy completion in children and young adults with ALL or AML. Twenty-eight studies, with 4138 patients, were included. Four studies reported infections in patients who did not undergo hematopoietic stem cell transplant (HSCT). Respiratory tract and urinary tract infections affected 9.9-72.5% and 2.9-19.8% of patients, respectively. Twelve studies reported infections in patients treated with HSCT. Late bacterial, viral and fungal infections affected 3.9-38.5%, 16.1-66.7%, and 0.2-41.7% of patients, respectively. Viral hepatitis affected 0.8-75.4% of patients from 12 studies. Our review suggests that infections are a frequent complication after treatment for leukemia in children, especially after HSCT and identifies several knowledge gaps in the current literature.

Co-infection with human polyomavirus BK enhances gene expression and replication of human adenovirus

Immunocompromised patients are susceptible to multiple viral infections. Relevant interactions between co-infecting viruses might result from viral regulatory genes which trans-activate or repress the expression of host cell genes as well as the genes of any co-infecting virus. The aim of the current study was to show that the replication of human adenovirus 5 is enhanced by co-infection with BK polyomavirus and is associated with increased expression of proteins including early region 4 open reading frame 1 and both the large tumor antigen and small tumor antigen. Clinical samples of whole blood and urine from 156 hematopoietic stem cell transplant recipients were tested. We also inoculated adenocarcinomic human alveolar basal epithelial cells with both human adenovirus 5 and BK polyomavirus to evaluate if co-infection of viruses affected their replication. Data showed that adenovirus load was significantly higher in the plasma (mean 7.5 x 10³ ± 8.5 x 10² copies/ml) and urine (mean 1.9 x 10³ ± 8.0 x 10² copies/ml) of samples from patients with co-infections, in comparison to samples from patients with isolated adenovirus infection. In vitro co-infection led to an increased (8.6 times) expression of the adenovirus early region 4 open reading frame gene 48 hours post-inoculation. The expression of the early region 4 open reading frame gene positively correlated with the expression of BK polyomavirus large tumor antigen (r = 0.90, p < 0.0001) and small tumor antigen (r = 0.83, p < 0.001) genes. The enhanced expression of the early region 4 open reading frame gene due to co-infection with BK polyomavirus was associated with enhanced adenovirus, but not BK polyomavirus, replication. The current study provides evidence that co-infection of adenovirus and BK polyomavirus contributes to enhanced adenovirus replication. Data obtained from this study may have significant importance in the clinical setting.