Efficacy of low-dose zoster prophylaxis in patients undergoing allogeneic hematopoietic cell transplantation

Towards personalized prevention of Herpes zoster infection in patients with hematologic diseases or hematopoietic stem cell transplant recipients: a position paper from an <I>ad hoc</I> Italian expert panel

The identification of patients at high risk of Herpes zoster (HZ) requiring a preventive strategy with antiviral prophylaxis and anti-HZ vaccine is a clinically relevant issue in patients with immunological impairment. The absence of trials comparing vaccination to pharmacological prophylaxis or defining their sequential use makes the optimal preventive strategy uncertain. This article presents the results of group discussion among a panel of experts convened ad hoc to review the literature regarding antiviral prophylaxis and vaccine efficacy and safety in populations with malignant and non-malignant hematologic diseases, and in subjects submitted to hematopoietic stem cell transplantation. The expert panel used consensus methodology and proposed solutions for preventive strategies, producing advice for the management of the most relevant unmet clinical needs. This comprehensive overview aims to support the practice of pharmacological and vaccination-based HZ prevention and inform the design and conduct of new studies in the field.

Infectious Disease Considerations in Chronic Graft-versus-Host Disease and Transplantation Survivors

Chronic graft-versus-host disease is a frequent and serious complication of allogeneic hematopoietic cell transplantation and is associated with an increased risk of serious infections. Impaired humoral immunity increases the risk of recurrent or severe sinopulmonary infections, and functional asplenia predisposes to infections from encapsulated organisms. Herpesvirus infections and community-acquired respiratory viral infections are problematic as well. Pneumocystis pneumonia remains a risk, and mold infections occur in some patients. Understanding the epidemiology and pathophysiology of these infections is important for determining optimal monitoring and prophylaxis, and guiding patient counseling.

Long-term incidence of varicella zoster virus disease in adults receiving single-unit cord blood transplantation

BACKGROUND

Varicella zoster virus (VZV) disease is a common complication after allogeneic hematopoietic cell transplantation (HCT). However, research into the long-term incidence of VZV disease in adults receiving cord blood transplantation (CBT) has been limited.

OBJECTIVE

The objective of this study was to evaluate the incidence, risk factors, and clinical impact of VZV disease after CBT with a long-term follow-up in our institute.

STUDY DESIGN

We retrospectively analyzed the data for 156 adult patients who received single-unit CBT at our institute between 2007 and 2020, who achieved neutrophil engraftment and survived at least 100 days without recurrence of the underlying disease.

RESULTS

VZV disease occurred in 61 patients at a median of 608 days (range, 36 - 4090 days) after CBT. The cumulative incidence of VZV disease was 14% (95% confidence interval [CI], 9% to 20%) at 1 year and 40% (95% CI, 31% to 48%) at 5 years after CBT. Multivariate analysis showed that the cessation of antiviral prophylaxis was an independent risk factor for a higher risk of VZV disease (hazard ratio: 15.65, 95% CI: 6.59-37.21, P<0.001). The cumulative incidence of VZV disease was significantly lower in the long-term antiviral prophylaxis group given for around 1 year after CBT or the end of immunosuppressive therapy compared to the short-term antiviral prophylaxis group given for 35 days after CBT (P=0.005). Among patients who developed VZV disease, the median onset of VZV disease was significantly delayed in the long-term antiviral prophylaxis group compared to the short-term antiviral prophylaxis group (694 days vs 130 days, P<0.001), but the median onset of VZV disease after the cessation of antiviral prophylaxis was not significantly different between long-term and short-term antiviral prophylaxis (166 days vs 95 days, P=0.087).

CONCLUSION

These data demonstrated that the long-term incidence of VZV disease was relatively high in adult patients receiving CBT. Given that the incidence of VZV disease after the cessation of antiviral prophylaxis remained high, additional interventions, such as recombinant zoster vaccine administration, could be required to prevent VZV disease in long-term adult survivors after CBT.

Cytomegalovirus and other herpesviruses after hematopoietic cell and solid organ transplantation: From antiviral drugs to virus-specific T cells

Herpesviruses can either cause primary infection or may get reactivated after both hematopoietic cell and solid organ transplantations. In general, viral infections increase post-transplant morbidity and mortality. Prophylactic, preemptive, or therapeutically administered antiviral drugs may be associated with serious side effects and may induce viral resistance. Virus-specific T cells represent a valuable addition to antiviral treatment, with high rates of response and minimal side effects. Even low numbers of virus-specific T cells manufactured by direct selection methods can reconstitute virus-specific immunity after transplantation and control viral replication. Virus-specific T cells belong to the advanced therapy medicinal products, and their production is regulated by appropriate legislation; also, strict safety regulations are required to minimize their side effects.

Safety and reactogenicity of the recombinant zoster vaccine after allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (HCT) recipients are at increased risk for varicella zoster virus (VZV) reactivation and associated complications. A nonlive adjuvanted recombinant zoster vaccine (RZV) has been developed to prevent herpes zoster (HZ), but there are no recommendations for use in this population. In this single-center prospective observational cohort study, we assessed the safety and reactogenicity of RZV, as well as incidence of graft-versus-host disease (GVHD) and confirmed cases of HZ after vaccination. Between December of 2018 and June of 2020, patients aged ≥18 years received 2 doses of RZV between 9 and 24 months after HCT, with the doses separated by ≥8 weeks. One hundred and fifty-eight patients (mean age, 55 years; 42% women) received ≥1 dose (total vaccinated cohort), and 150 patients (95%) received 2 doses (modified total vaccinated cohort). Solicited reactions occurred in 92.1% of patients (grade 3, 32.5%), owing mostly to injection site pain, which occurred in 86% (grade 3, 16%). The cumulative incidence of GVHD in the peri-vaccination period was no different than in historical controls (adjusted incidence rate ratio, 1.05; 95% confidence interval, 0.8-1.38). There were 4 cases of HZ in the total vaccinated cohort (2.5%) and 3 cases in the modified total vaccinated cohort (28.3/1000 person-years). Among recipients of allogeneic HCT, RZV was safe, tolerable, and did not increase rates of GVHD. Future clinical trials are needed to determine the immunogenicity and efficacy of RZV in this population.

Late-occurring infections in a contemporary cohort of hematopoietic cell transplantation survivors

Background

There is a paucity of studies describing the incidence and risk factors for late‐occurring (≥1 year) infectious complications in contemporary survivors of hematopoietic cell transplantation (HCT).

Methods

This was a retrospective cohort study of 641 1‐year survivors of HCT, transplanted between 2010 and 2013 as adults, and in remission from their primary disease. Standardized definitions were used to characterize viral, fungal, and bacterial infections. Cumulative incidence of infections was calculated, with relapse/progression considered as a competing risk event. Fine‐Gray subdistribution hazard ratio estimates and 95% confidence intervals (CI) were obtained, adjusted for relevant covariates.

Results

Median age at HCT was 55.2 years (range 18.1–78.1 years); 54.0% were survivors of allogeneic HCT. The 5‐year cumulative incidence of a late‐occurring infection for the entire cohort was 31.6%; the incidence of polymicrobial (≥2) infections was 10.1%. In survivors who developed at least one infection, the 5‐year incidence of a subsequent infection was 45.3%. Among allogeneic HCT survivors, patients with acute lymphoblastic (HR = 1.82 95% CI [1.12–2.96]) or myeloid (HR = 1.50 95% CI [1.02–2.20]) leukemia, and those with an elevated HCT‐Comorbidity index score (HR = 1.09 95% CI [1.01–1.17]) were more likely to develop late‐occurring infections; there was an incremental risk associated with severity of graft versus host disease (GVHD) at 1‐year post‐HCT (mild: HR = 2.17, 95% CI [1.09–4.33]; moderate/severe: HR = 3.78, 95% CI [1.90–7.53]; reference: no GVHD).

Conclusions

The burden of late‐occurring infections in HCT survivors is substantial, and there are important patient‐ and HCT‐related modifiers of risk over time. These findings may help guide personalized screening and prevention strategies to improve outcomes after HCT.