Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances

To proceed or delay? The dilemma of community-acquired respiratory viruses in adults and pediatrics before allogeneic stem cell transplantation and chimeric-antigen-receptor T-cell therapy

PURPOSE OF REVIEW

This review explores the impact of community-acquired respiratory virus (CARV) infections on outcomes before proceeding with hematopoietic cell transplantation (HCT) and chimeric-antigen-receptor T-cell (CAR-T) therapy recipients and which conditions should be considered to delay or proceed with cell therapy. It aims to assess current practices, the risks associated with early CARV infections in cell therapy recipients, and potential modifications to reduce complications and improve clinical outcomes if delay is not an option.

RECENT FINDINGS

Studies have shown that pretransplant CARV infections, particularly those with symptomatic lower respiratory tract disease (LRTD), are linked to increased mortality and prolonged hospitalization after hematopoietic stem cell transplant. The timing of CARV infection regarding the transplant, the type of CARV, and the intensity of immunosuppressive conditioning, among others, are key factors influencing outcomes. Additionally, recent research highlights the potential benefits of delaying transplantation, optimizing immunosuppression, and reducing the duration of neutropenia and lymphopenia to mitigate the risk of severe infections.

SUMMARY

Key challenges include determining the optimal timing for transplant in CARV-positive patients, managing cell procedures, and minimizing risk factors to reduce the development of a severe course resulting in poor outcome. Current practices often prioritize timely transplant/CAR-T procedures but may need to be adjusted to account for CARV infections. Implementing strategies such as reduced-intensity conditioning, enhanced infection prevention measures, and antiviral therapy could significantly impact patient outcomes, particularly in preventing progression to LRTD and reducing the risk for fatal outcome.

Assessment of the Immunodeficiency Scoring Index for Predicting Outcomes After Respiratory Syncytial Virus Infection in Allogeneic Stem Cell Transplant Recipients

Respiratory syncytial virus (RSV) is a common cause of respiratory infections in allogeneic hematopoietic stem cell transplant (allo-HCT) recipients. The immunodeficiency scoring index (ISI) has shown predictive value in assessing the risk of progression to lower respiratory tract disease (LRTD) and mortality in allo-HCT recipients developing RSV infection but requires further validation in external cohorts. This retrospective study examined RSV episodes in adult allo-HCT recipients from December 2013 to June 2023 at 2 Spanish hospitals. The aim was to validate the predictive value of ISI for LRTD progression and infectious mortality at day +100 after RSV detection and to identify other conditions associated with disease severity. A total of 207 allo-HCT recipients developed 262 episodes of RSV infection, of which 102 (39%) progressed to LRTD. Independent variables significantly associated with LRTD risk were umbilical cord blood transplant [odds ratio (OR) 2.72, P = .016], high-risk ISI (OR 4.4, P = .008), the transplant periods between 2014 and 2016 (OR 0.31, P = .007) and after 2020 (OR 0.13, P = .026), and ribavirin use (OR 0.49, P = .047). The 100-day infectious mortality rate after RSV detection was 8.7%, increasing to 18% in those with LRTD. Variables significantly associated with the risk of mortality were donor/recipient HLA mismatch [hazard ratio (HR) 5.09, P = .011] and absolute lymphocyte count (ALC) [<0.2 × 10^9/L (HR 11.27, P = .003) and 0.2 to 1 × 10^9/L (HR 8.21, P = .008)]. ISI was associated with mortality (HR 6.8, P = .006) only when ALC categories were excluded from the multivariable model. In transplant recipients with RSV infection, a high-risk ISI category is associated with an increased risk of progression to LRTD, whereas ribavirin appears to have a protective role. Mortality in LRTD cases was influenced by HLA mismatch and different levels of lymphopenia, factors which if incorporated may enhance the ISI's ability to predict mortality.

M1 enrichment facilitates virus detection in patients with allogeneic hematopoietic stemcell transplantation

Due to the severe consequences of viral infection in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients, the routine use of polymerase chain reaction (PCR) screening of viruses is common in clinic, while the sensitivities of molecular methods are not always sufficient for blood samples. We aimed to increase the detection efficiency of viremia in allo-HSCT patients with M1 bead enrichment. Blood samples of allo-HSCT patients with fever were collected. Simultaneously with analyses of real-time PCR without enrichment, M1 bead enrichment followed by real-time PCR was applied to detect possible viruses in these samples, and metagenomic next-generation sequencing analyses were also applied in 10 samples negative with real-time PCR without enrichment. Various species of viruses were detected with M1 enrichment method. Significantly, some viruses that had not been found by real-time PCR without M1 enrichment were also detected by those with M1 enrichment and verified by metagenomic next-generation sequencing analyses. Furthermore, blood samples enriched with M1 beads had lower Ct values of real-time PCR assay than those that had not been treated. In conclusion, M1 bead enrichment increased the detection efficiency of most viruses in hematological malignancy patients.

Outcome of Human Parainfluenza Virus infection in allogeneic stem cell transplantation recipients: possible impact of ribavirin therapy

BACKGROUND

This retrospective study focused on analyzing community-acquired respiratory virus (CARV) infections, in particular human parainfluenza virus (hPIV) after allogeneic stem cell transplant (allo-SCT) in adults recipients. It aimed to assess the impact of ribavirin treatment, clinical characteristics, and risk factors associated with lower respiratory tract disease (LRTD) progression and all-cause mortality.

PATIENTS AND METHODS

The study included 230 allo-SCT recipients diagnosed with hPIV between December 2013 and June 2023. Risk factors for the development of LRTD, disease severity, and mortality were analyzed. Ribavirin treatment was administered at physician discretion in 61 out of 230 cases (27%).

RESULTS

Risk factors for LRTD progression in multivariate analysis were corticosteroids > 30 mg/day (Odds ratio (OR) 3.5, 95% Confidence Interval (C.I.) 1.3-9.4, p = 0.013), fever at the time of hPIV detection (OR 3.89, 95% C.I. 1.84-8.2, p < 0.001), and absolute lymphocyte count (ALC) < 0.2 × 109/L (OR 4.1, 95% C.I. 1.42-11.9, p = 0.009). In addition, the study found that ribavirin therapy significantly reduced progression to LRTD [OR 0.19, 95% C.I. 0.05-0.75, p = 0.018]. Co-infections (OR 5.7, 95% C.I. 1.4-23.5, p = 0.015) and ALC < 0.2 × 109/L (OR 17.7, 95% C.I. 3.6-87.1, p < 0.001) were independently associated with higher day + 100 after hPIV detection all-cause mortality. There were no significant differences in all-cause mortality and infectious mortality at day + 100 between the treated and untreated groups.

CONCLUSION

ALC, corticosteroids, and fever increased the risk for progression to LRTD while ribavirin decreased the risk. However, mortality was associated with ALC and co-infections. This study supports further research of ribavirin therapy for hPIV in the allo-HSCT setting.

Pitfalls in definitions on respiratory viruses and particularities of Adenovirus infection in hematopoietic cell transplantation patients: Recommendations from the EBMT practice harmonization and guidelines committee

In 2023, the EBMT Practice harmonization and Guidelines Committee partnered with the EBMT Infection Diseases Working Party (IDWP) to undertake the task of delivering best practice recommendations, aiming to harmonize by expert consensus, the already existing definitions and future epidemiological and clinical studies among centers of the EBMT network. To attain this objective, a group of experts in the field was convened. The workgroup identified and discussed some critical aspects in definitions of community-acquired respiratory viruses (CARV) and adenovirus (ADV) infections in recipient of hematopoietic cell transplant (HCT). The methodology involved literature review and expert consensus. For CARV, expert consensus focused on defining infection severity, infection duration, and establishing criteria for lower respiratory tract disease (LRTD). For ADV, the expert consensus focused on surveillance methods and the definitions of ADV infection, certainty levels of disease, response to treatment, and attributable mortality. This consensus workshop provided indications to EBMT community aimed at facilitating data collection and consistency in the EBMT registry for respiratory viral infectious complications.

Are any specific respiratory viruses more severe than others in recipients of allogeneic stem cell transplantation? A focus on lower respiratory tract disease

In the general population, influenza virus, respiratory syncytial virus, and SARS-CoV-2 are considered the most severe community-acquired respiratory viruses (CARVs). However, allogeneic stem cell transplant (allo-SCT) recipients may also face severe courses from other CARVs. This retrospective study compared outcomes of various CARV lower respiratory tract diseases (LRTD) in 235 adult allo-SCT recipients, excluding co-infection episodes. We included 235 adults allo-SCT recipients experiencing 353 CARV LRTD consecutive episodes (130 rhinovirus, 63 respiratory syncytial virus, 43 influenza, 43 human parainfluenza virus, 23 human metapneumovirus, 19 Omicron SARS-CoV-2, 17 common coronavirus, 10 adenovirus and 5 human bocavirus) between December 2013 and June 2023. Day 100 overall survival ranged from 78% to 90% without significant differences among CARV types. Multivariable analysis of day 100 all-cause mortality identified corticosteroid use of >1 to <30 mg/d [Hazard ratio (HR) 2.45, p = 0.02) and ≥30 mg/d (HR 2.20, p = 0.015) along with absolute lymphocyte count <0.2 × 109/L (HR 5.82, p < 0.001) and number of CARV episodes as a continuous variable per one episode increase (HR 0.48, p = 0.001) as independent risk factors for all-cause mortality. Degree of immunosuppression, rather than intrinsic CARV virulence, has the most significant impact on mortality in allo-SCT recipients with CARV-LRTD.

Omicron SARS-CoV-2 infection management and outcomes in patients with hematologic disease and recipients of cell therapy

Introduction

Scarce real-life data exists for COVID-19 management in hematologic disease (HD) patients in the Omicron era.

Purpose

To assess the current clinical management and outcome of SARS-CoV-2 infection diagnosed, identify the risk factors for severe outcomes according to the HD characteristics and cell therapy procedures in a real-world setting.

Methods

A retrospective observational registry led by the Spanish Transplant Group (GETH-TC) with 692 consecutive patients with HD from December 2021 to May 2023 was analyzed.

Results

Nearly one-third of patients (31%) remained untreated and presented low COVID-19-related mortality (0.9%). Nirmatrelvir/ritonavir was used mainly in mild COVID-19 cases in the outpatient setting (32%) with a low mortality (1%), while treatment with remdesivir was preferentially administered in moderate-to-severe SARS-CoV-2 infection cases during hospitalization (35%) with a mortality rate of 8.6%. The hospital admission rate was 23%, while 18% developed pneumonia. COVID-19-related mortality in admitted patients was 14%. Older age, autologous hematopoietic stem cell transplantation (SCT), chimeric antigen receptor T-cell therapy, corticosteroids and incomplete vaccination were factors independently associated with COVID-19 severity and significantly related with higher rates of hospital admission and pneumonia. Incomplete vaccination status, treatment with prior anti-CD20 monoclonal antibodies, and comorbid cardiomyopathy were identified as independent risk factors for COVID-19 mortality.

Conclusions

The results support that, albeit to a lower extent, COVID-19 in the Omicron era remains a significant problem in HD patients. Complete vaccination (3 doses) should be prioritized in these immunocompromised patients. The identified risk factors may help to improve COVID-19 management to decrease the rate of severe disease, ICU admissions and mortality.