Pretransplant vaccinations in allogeneic stem cell transplantation donors and recipients: an often-missed opportunity for immunoprotection?

Adoptive transfer of donor B lymphocytes: a phase 1/2a study for patients after allogeneic stem cell transplantation

ABSTRACT

Immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is slow and patients carry a high and prolonged risk of opportunistic infections. We hypothesized that the adoptive transfer of donor B cells can foster after HSCT immuno-reconstitution. Here, we report, to our knowledge, the results of a first-in-human phase 1/2a study aimed to evaluate the feasibility and safety of adoptively transferred donor B cells and to test their activity upon recall vaccination. Good manufactoring practice (GMP) B-cell products were generated from donor apheresis products using 2-step magnetic cell separation. Fifteen patients who had undergone allo-HSCT were enrolled and treated after taper of immunosuppression (median, day +148; range, 130-160). Patients received 4 different doses of B cells (0.5 × 106 to 4.0 × 106 B cells per kg body weight). To test the activity of infused donor memory B cells in vivo, patients were vaccinated with a pentavalent vaccine 7 days after B-cell transfer. We observed the mobilization of plasmablasts and an increase in serum titers against vaccine antigens, with a stronger response in patients receiving higher B-cell numbers. Analysis of immunoglobulin VH-sequences by next-generation sequencing revealed that plasmablasts responding to vaccination originated from memory B-cell clones from the donor. Donor B-cell transfer was safe, as no Epstein-Barr virus (EBV) reactivation was observed, and only low-grade graft-versus-host disease (GVHD) occurred in 4 out of 15 patients. This pilot trial may pave the way for further studies exploring the adoptive transfer of memory B cells to reduce the frequency of infections after allo-HSCT. This trial was registered at ClinicalTrial.gov as #NCT02007811.

COVID-19 after hematopoietic cell transplantation and chimeric antigen receptor (CAR)-T-cell therapy

More than 3 years have passed since Coronavirus disease 2019 (COVID-19) was declared a global pandemic, yet COVID-19 still severely impacts immunocompromised individuals including those treated with hematopoietic cell transplantation (HCT) and chimeric antigen receptor-T-cell therapies who remain at high risk for severe COVID-19 and mortality. Despite vaccination efforts, these patients have inadequate responses due to immunosuppression, which underscores the need for additional preventive approaches. The optimal timing, schedule of vaccination, and immunological correlates for protective immunity remain unknown. Antiviral therapies used early during disease can reduce mortality and severity due to COVID-19. The combination or sequential use of antivirals could be beneficial to control replication and prevent the development of treatment-related mutations in protracted COVID-19. Despite conflicting data, COVID-19 convalescent plasma remains an option in immunocompromised patients with mild-to-moderate disease to prevent progression. Protracted COVID-19 has been increasingly recognized among these patients and has been implicated in intra-host emergence of SARS-CoV-2 variants. Finally, novel SARS-CoV2-specific T-cells and natural killer cell-boosting (or -containing) products may be active against multiple variants and are promising therapies in immunocompromised patients.

Impact of Donor and Recipient SARS-CoV-2 Vaccination or Infection on Immunity after Hematopoietic Cell Transplantation

The role of donor and recipient Coronavirus disease 2019 (COVID-19) immunologic status pre-transplantation has not been fully investigated in allogeneic hematopoietic stem cell transplantation (HSCT) recipients. Given the poor immunogenicity to vaccines in this population and the serious outcomes of COVID-19, adoptive transfer of immunity may offer important insight into improving protection for this vulnerable population. In this study, we evaluated the role of adoptive transfer of immunity at 1 month post-transplantation and 6 months post-transplantation after vaccination of recipients, based on pre-transplantation severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and infection exposures of both recipient and donor. Using banked specimens from related donor allogeneic HSCT recipients and clinical data from both donors and recipients, anti-Spike (S) IgG titers were analyzed at 1, 3, and 6 months post-transplantation according to prior SARS-CoV-2 immunologic exposures. Recipients were excluded if they had received SARS-CoV-2 monoclonal antibodies or had infection in the first 6 months post-transplantation. Of the 53 recipient-donor pairs, 29 donors and 24 recipients had prior SARS-CoV-2 immunologic exposure. Recipient-donor pairs with no prior SARS-CoV-2 exposure (D0R0) had significantly lower anti-S IgG titers at 1 month compared to those with prior exposures (D1R1) (D0R0: median, 2.43 [interquartile range (IQR), .41 to 3.77]; D1R1: median, 8.42; IQR, 5.58 to 12.20]; P = .008). At 6 months, anti-S IgG titers were higher in recipients who were vaccinated at 3 months post-transplantation in the D1R1 cohort (median IgG, 148.34; IQR, 92.36 to 204.33) compared with the D0R0 cohort (median IgG, 38.74; IQR, 8.93 to 119.71). Current strategies should be optimized to enhance SARS-CoV-2 protection for HSCT recipients, including augmentation of the immune response for both donors and recipients prior to transplantation.

Long-Term Immunity Against Tetanus and Diphtheria after Vaccination of Allogeneic Stem Cell Transplantation Recipients

Revaccination against tetanus and diphtheria after allogeneic hematopoietic stem cell transplantation (HCT) is usually effective, but the duration of the immunity is unknown. We conducted this study to evaluate humoral immunity to tetanus and diphtheria in long-term survivors and to provide knowledge regarding the need for boosters. The median time from HCT to blood sampling was 14 years (range, 8 to 40 years). All patients had received at least 3 doses of vaccines against both tetanus and diphtheria, either monovalent or combination vaccines containing a full dose of the diphtheria toxoid component. In addition, 1 or more booster doses were administered to 21 of the 146 patients (14%). On enzyme-linked immunosorbent assay, levels <.1 IU/mL for diphtheria and <.01 IU/mL for tetanus were considered low or seronegative. Values between .01 and .5 IU/mL for tetanus and between .1 and 1.0 IU/mL for diphtheria were considered to represent partial protection, and levels >.5 and >1.0 IU/mL were considered high and protective, respectively. In all, 39% of patients were seronegative against diphtheria, 52% had some protection, and 9% had a high titer. In contrast, no patient had become seronegative to tetanus, 32% had "partial protection" against tetanus and 68% had a high titer. In multivariate analysis, active graft-versus-host-disease, sex, or time from sampling did not affect the probability of becoming seronegative or seropositive. Younger age was associated with lower antibody levels to tetanus toxoid, but age was not correlated with antibody levels against diphtheria toxoid. Tetanus immunity was maintained after vaccination in most long-term survivors, but immunity against diphtheria was poor, and boosters should be considered.

Hematopoietic stem cell donor vaccination with cytomegalovirus triplex augments frequencies of functional and durable cytomegalovirus-specific T cells in the recipient: A novel strategy to limit antiviral prophylaxis

To enhance protective cytomegalovirus (CMV)-specific T cells in immunosuppressed recipients of an allogeneic hematopoietic cell transplant (HCT), we evaluated post-HCT impact of vaccinating healthy HCT donors with Triplex. Triplex is a viral vectored recombinant vaccine expressing three immunodominant CMV antigens. The vector is modified vaccinia Ankara (MVA), an attenuated, non-replicating poxvirus derived from the vaccinia virus strain Ankara. It demonstrated tolerability and immunogenicity in healthy adults and HCT recipients, in whom it also reduced CMV reactivation. Here, we report feasibility, safety, and immunological outcomes of a pilot phase 1 trial (NCT03560752 at ClinicalTrials.gov) including 17 CMV-seropositive recipients who received an HCT from a matched related donor (MRD) vaccinated with 5.1 × 108 pfu/ml of Triplex before cell harvest (median 15, range 11-28 days). Donor and recipient pairs who committed to participation in the trial resulted in exceptional adherence to the protocol. Triplex was well-tolerated with limited adverse events in donors and recipients, who all engrafted with full donor chimerism. On day 28 post-HCT, levels of functional vaccinia- and CMV-specific CD137+ CD8+ T cells were significantly higher (p < .0001 and p = .0174, respectively) in recipients of Triplex vaccinated MRD than unvaccinated MRD (control cohort). Predominantly, central and effector memory CMV-specific T-cell responses continued to steadily expand through 1-year follow-up. CMV viremia requiring antivirals developed in three recipients (18%). In summary, this novel approach represents a promising strategy applicable to different HCT settings for limiting the use of antiviral prophylaxis, which can impair and delay CMV-specific immunity, leading to CMV reactivation requiring treatment.

Influence of Acute and Chronic Graft-Versus-Host Disease on Persistence of Antibodies against Measles, Mumps, Rubella and Varicella in the First Year after Autologous or Allogeneic Hematopoietic Stem Cell Transplantation

Patients after hematopoietic stem cell transplantation (HSCT) are vulnerable to infections due to severe immunosuppression. Live-attenuated vaccines are contraindicated for two years after HSCT. The aim of this study was to assess the persistence of antibodies against measles, mumps, rubella and varicella in the first year after HSCT. Forty patients undergoing autologous (n = 12) or allogeneic (n = 28) HSCT were included in this study. Specific IgG antibodies to measles, mumps, rubella and varicella virus in serum samples were assessed by the LIAISON XL, a fully automated chemiluminescence analyzer, at seven different time points starting one week before HSCT and up to 12 months after HSCT. At baseline, before HSCT, most patients showed antibodies against measles (100%), mumps (80%), rubella (97.5%) and varicella (92.5%). Although titers declined over time, most patients retained antibodies against measles (92.5%), mumps (62.5%), rubella (87.5%) and varicella (85%) up to 12 months after HSCT. There was no significant difference between patients with and without GvHD concerning persistence of antibody titers. Significantly higher varicella titers were detected in autologous patients compared to patients with chronic GvHD. Considering that live-attenuated vaccines should not be administered during the first year after HSCT, the persistence of antibodies against these diseases is relevant.

Functional SARS-CoV-2-specific T cells of donor origin in allogeneic stem cell transplant recipients of a T-cell-replete infusion: A prospective observational study

In the current post-pandemic era, recipients of an allogeneic hematopoietic stem cell transplant (HCT) deserve special attention. In these vulnerable patients, vaccine effectiveness is reduced by post-transplant immune-suppressive therapy; consequently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) is often associated with elevated morbidity and mortality. Characterizing SARS-CoV-2 adaptive immunity transfer from immune donors to HCT recipients in the context of immunosuppression will help identify optimal timing and vaccination strategies that can provide adequate protection to HCT recipients against infection with evolving SARS-CoV-2 variants. We performed a prospective observational study (NCT04666025 at ClinicalTrials.gov) to longitudinally monitor the transfer of SARS-CoV-2-specific antiviral immunity from HCT donors, who were either vaccinated or had a history of COVID-19, to their recipients via T-cell replete graft. Levels, function, and quality of SARS-CoV-2-specific immune responses were longitudinally analyzed up to 6 months post-HCT in 14 matched unrelated donor/recipients and four haploidentical donor/recipient pairs. A markedly skewed donor-derived SARS-CoV-2 CD4 T-cell response was measurable in 15 (83%) recipients. It showed a polarized Th1 functional profile, with the prevalence of central memory phenotype subsets. SARS-CoV-2-specific IFN-γ was detectable throughout the observation period, including early post-transplant (day +30). Functionally experienced SARS-CoV-2 Th1-type T cells promptly expanded in two recipients at the time of post-HCT vaccination and in two others who were infected and survived post-transplant COVID-19 infection. Our data suggest that donor-derived SARS-CoV-2 T-cell responses are functional in immunosuppressed recipients and may play a critical role in post-HCT vaccine response and protection from the fatal disease.

Clinical trial registration

clinicaltrials.gov, identifier NCT04666025.

Cross-protective antibodies against common endemic respiratory viruses

Respiratory syncytial virus (RSV), human metapneumovirus (HMPV), and human parainfluenza virus types one (HPIV1) and three (HPIV3) can cause severe disease and death in immunocompromised patients, the elderly, and those with underlying lung disease. A protective monoclonal antibody exists for RSV, but clinical use is limited to high-risk infant populations. Hence, therapeutic options for these viruses in vulnerable patient populations are currently limited. Here, we present the discovery, in vitro characterization, and in vivo efficacy testing of two cross-neutralizing monoclonal antibodies, one targeting both HPIV3 and HPIV1 and the other targeting both RSV and HMPV. The 3 × 1 antibody is capable of targeting multiple parainfluenza viruses; the MxR antibody shares features with other previously reported monoclonal antibodies that are capable of neutralizing both RSV and HMPV. We obtained structures using cryo-electron microscopy of these antibodies in complex with their antigens at 3.62 Å resolution for 3 × 1 bound to HPIV3 and at 2.24 Å for MxR bound to RSV, providing a structural basis for in vitro binding and neutralization. Together, a cocktail of 3 × 1 and MxR could have clinical utility in providing broad protection against four of the respiratory viruses that cause significant morbidity and mortality in at-risk individuals.

Evaluation of Safety and Immunogenicity of a Recombinant Receptor-Binding Domain (RBD)-Tetanus Toxoid (TT) Conjugated SARS-CoV-2 Vaccine (PastoCovac) in Recipients of Autologous Hematopoietic Stem Cell Transplantation Compared to the Healthy Controls; A Prospective, Open-Label Clinical Trial

Background: The urgent need for prompt SARS-CoV-2 immunization of hematopoietic stem cell transplant (HSCT) recipients in an endemic area raises many challenges regarding selecting a vaccine platform appropriate for HSCT recipients being economical for widespread use in developing countries. Methods: The trial is a prospective, single-group, open-label study to investigate the safety and serologic response of two doses of the recombinant receptor-binding domain (RBD)-Tetanus Toxoid (TT) conjugated SARS-CoV-2 vaccine (PastoCovac) early after autologous (auto) HSCT. For this reason, a total of 38 patients who completed the two-dose SARS-CoV-2 RBD-based vaccine between three to nine months after auto-HSCT and had an available anti-spike serologic test at three predefined time points of baseline and after the first and second doses and 50 healthy control individuals were included in the analysis. The primary outcome was defined as an increase in IgG Immune status ratio (ISR) to the cut-off value for the positive result (≥1.1) in the semiquantitative test. Findings: The median time between auto-HSCT and vaccination was 127 days. No participant reported any significant adverse effects (Grade 3). Pain at the injection site was the most common adverse event. The ISR increased significantly (p < 0.001) during the three-time point sampling for both patients and healthy control groups. In patients, the mean ISR increased from 1.39 (95% CI: 1.13−1.65) at baseline to 2.48 (1.93−3.03) and 3.73 (3.13−4.38) following the first and second dosages, respectively. In multivariate analysis, the higher count of lymphocytes [OR: 8.57 (95% CI: 1.51−48.75); p = 0.02] and history of obtaining COVID-19 infection before transplantation [OR: 6.24 (95% CI: 1.17−33.15); p = 0.03] remained the predictors of the stronger immune response following two doses of the RBD-TT conjugated vaccine. Moreover, we found that the immunogenicity of the COVID-19 vaccine shortly after transplantation could be influenced by pre-transplant COVID-19 vaccination. Interpretation: The RBD-TT conjugated SARS-CoV-2 vaccine was safe, highly immunogenic, and affordable early after autologous transplants. Funding: This work was mainly financed by the Hematology-Oncology-Stem Cell Transplantation Research Center (HORCSCT) of Tehran University and the Pasteur Institute of Iran.

Three doses of a recombinant conjugated SARS-CoV-2 vaccine early after allogeneic hematopoietic stem cell transplantation: predicting indicators of a high serologic response-a prospective, single-arm study

Background

Allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients must be vaccinated against SARS-CoV-2 as quickly as possible after transplantation. The difficulty in obtaining recommended SARS-CoV-2 vaccines for allo-HSCT recipients motivated us to utilize an accessible and affordable SARS-CoV-2 vaccine with a recombinant receptor-binding domain (RBD)-tetanus toxoid (TT)-conjugated platform shortly after allo-HSCT in the developing country of Iran.

Methods

This prospective, single-arm study aimed to investigate immunogenicity and its predictors following a three-dose SARS-CoV-2 RBD-TT-conjugated vaccine regimen administered at 4-week (± 1-week) intervals in patients within 3-12 months post allo-HSCT. An immune status ratio (ISR) was measured at baseline and 4 weeks (± 1 week) after each vaccine dose using a semiquantitative immunoassay. Using the median ISR as a cut-off point for immune response intensity, we performed a logistic regression analysis to determine the predictive impact of several baseline factors on the intensity of the serologic response following the third vaccination dose.

Results

Thirty-six allo-HSCT recipients, with a mean age of 42.42 years and a median time of 133 days between hematopoietic stem cell transplant (allo-HSCT) and the start of vaccination, were analyzed. Our findings, using the generalized estimating equation (GEE) model, indicated that, compared with the baseline ISR of 1.55 [95% confidence interval (CI) 0.94 to 2.17], the ISR increased significantly during the three-dose SARS-CoV-2 vaccination regimen. The ISR reached 2.32 (95% CI 1.84 to 2.79; p = 0.010) after the second dose and 3.87 (95% CI 3.25 to 4.48; p = 0.001) after the third dose of vaccine, reflecting 69.44% and 91.66% seropositivity, respectively. In a multivariate logistic regression analysis, the female sex of the donor [odds ratio (OR) 8.67; p = 0.028] and a higher level donor ISR at allo-HSCT (OR 3.56; p = 0.050) were the two positive predictors of strong immune response following the third vaccine dose. No serious adverse events (i.e., grades 3 and 4) were observed following the vaccination regimen.

Conclusions

We concluded that early vaccination of allo-HSCT recipients with a three-dose RBD-TT-conjugated SARS-CoV-2 vaccine is safe and could improve the early post-allo-HSCT immune response. We further believe that the pre-allo-HSCT SARS-CoV-2 immunization of donors may enhance post-allo-HSCT seroconversion in allo-HSCT recipients who receive the entire course of the SARS-CoV-2 vaccine during the first year after allo-HSCT.

Frequently Asked Questions on Coronavirus Disease 2019 Vaccination for Hematopoietic Cell Transplantation and Chimeric Antigen Receptor T-Cell Recipients From the American Society for Transplantation and Cellular Therapy and the American Society of Hematology

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), disproportionately affects immunocompromised and elderly patients. Not only are hematopoietic cell transplantation (HCT) and chimeric antigen receptor (CAR) T-cell recipients at greater risk for severe COVID-19 and COVID-19-related complications, but they also may experience suboptimal immune responses to currently available COVID-19 vaccines. Optimizing the use, timing, and number of doses of the COVID-19 vaccines in these patients may provide better protection against SARS-CoV-2 infection and better outcomes after infection. To this end, current guidelines for COVID-19 vaccination in HCT and CAR T-cell recipients from the American Society of Transplantation and Cellular Therapy Transplant Infectious Disease Special Interest Group and the American Society of Hematology are provided in a frequently asked questions format.

Tick-Borne Encephalitis Specific Lymphocyte Response after Allogeneic Hematopoietic Stem Cell Transplantation Predicts Humoral Immunity after Vaccination

The aim of this prospective study was to assess lymphocyte proliferative and cytokine response prior to and following tick-borne encephalitis (TBE) immunization among patients after allogeneic hematopoietic stem cell transplantation (HSCT). Seventeen adult patients 11–13 months after HSCT and eight unvaccinated healthy adults received up to three TBE vaccinations. Following in vitro stimulation with TBE-antigen, lymphocyte proliferation and cytokine secretion (IL-2, IL-10, IL-13, TNF-alpha, IFN-gamma, GM-CSF) were analyzed by thymidine incorporation assay and the Luminex system. Ten patients (59%) showed significant baseline TBE-specific lymphocyte proliferation (stimulation index (SI) > 3) prior to vaccination, but none of the unvaccinated controls (p = 0.002). All patients with a TBE-specific antibody response after two vaccinations (at least 2-fold increase of neutralization test titers) exhibited a strong TBE-specific lymphocyte proliferative response at baseline (SI > 10). Patients with sibling donors had a significantly stronger baseline TBE-specific lymphocyte proliferative and IL-13 cytokine response than patients with unrelated donors (p < 0.05). In conclusion, a relevant proportion of patients showed TBE-specific lymphocyte proliferative and cytokine responses prior to vaccination after HSCT, which predicted the humoral response to the vaccine. Patients with vaccinated sibling donors were more likely to elicit a cellular immune response than patients with unrelated donors of unknown vaccination status.

Pneumococcal Vaccination in Immunocompromised Hosts: An Update

Infections with the pathogen, Streptococcus pneumoniae, are a common cause of morbidity and mortality worldwide. It particularly affects those at the extremes of age and immunocompromised individuals. Preventing pneumococcal disease is paramount in at risk individuals, and pneumococcal vaccination should be offered. Here, we discuss the role of pneumococcal vaccination in specific groups of immunocompromised hosts.

Immune Status Against Hepatitis B in Patients After Allogeneic Hematopoietic Cell Transplantation-Factors Affecting Early and Long-Lasting Maintenance of Protective Anti-HBs Titers

The immunization of allogeneic hematopoietic cell transplantation (HCT) recipients against vaccine-preventable diseases is a part of posttransplantation guidelines. We conducted a prospective study to assess clinical and immunological parameters that would determine the response and long-term maintenance of protective antibody titers upon the hepatitis B virus (HBV) vaccination after HCT. The investigated variables included: vaccination of the HCT recipients and their donors prior to HCT, chronic graft versus host disease (cGVHD) and the timing of post-HCT vaccination, and B- and T-cell subtype status. Forty-two patients were immunized with three or more doses of recombinant hepatitis B surface antigen (rHBsAg) administered according to the individualized schedule of 0-1-2-6-(12) months. After vaccination, seroconversion was achieved in the whole group. The vaccines were categorized according to the antibody (Ab) titers as weak (WRs; 28.7%), good (GRs; 38%) or very good responders (VGRs; 3.3%). In multivariate logistic regression, severe cGVHD (OR= 15.5), and preceding donor immunization (OR= 0.13) were independent predictors of a weak response to vaccination. A prior belonging to the WR group impaired the durability of protection (OR= 0.17) at a median follow-up of 11.5 years. Patients with severe cGVHD showed a trend toward lower median Ab titers, although they required a higher rate of booster vaccine doses. All VGRs had CD4+ cells > 0.2 x 10⁶/L. There was a lower mean rate of CD4+IL2+ lymphocytes in WRs. Vaccination demonstrated the immunomodulatory effect on B-cell and T-cell subsets and a Th1/Th2 cytokine profile, while shifts depended on a history of severe cGVHD and the type of vaccine responder. To conclude, vaccination of HCT donors against HBV allows a better response to vaccination in the respective HCT recipients. Double doses of rHBsAg should be considered in patients with cGVHD and in those not immunized before HCT. A dedicated intensified vaccination schedule should be administered to WRs.

Hepatitis B reactivation in hematopoietic stem cell transplanted patients: 20 years of experience of a single center from a middle endemic country

Hematopoietic stem cell transplantation (HSCT) is a risk factor for viral hepatitis reactivations because it affects lymphocyte number and functions. Latent hepatitis B virus (HBV) may stay in dormant form in hepatocytes and may be reactivated in prolonged immunosuppression. This study analyzes the incidence of reactivation of HBV infections in HSCT patients in a middle endemic country like Turkey. Five hundred and sixty-one HSCT patients from 1994 to 2015 were retrospectively evaluated. Sixty-six patients had a serologic feature of HBV infection. Fifteen patients were hepatitis B surface antigen (HBsAg)-positive patients (3 allogeneic and 12 autologous) while 51 of them were anti-hepatitis B core IgG (anti-HBc IgG)-positive patients (22 allogeneic and 29 autologous). Although under lamivudine prophylaxis, reactivation was seen in three of 12 (25%) chronic HBV (HBsAg positive) patients who received autologous HSCT and in two of the three HBsAg-positive patients who received allogeneic HSCT. Rate of reactivation in the whole HBsAg-positive group was 33%. Reactivation occurred on median 270th day (range: 60-730). Reverse seroconversion incidence was 10% on 133th day for HBsAg negative, but anti-HBc IgG-positive patients, which increased to 17% on 360th and to 23% on 1500th day. Cumulative incidence increased to 41% on 2280th day for isolated anti-HBc IgG-positive patients. Hepatitis B surface antibodies (anti-HBs) were found to be protective as reactivation did not exceed 11% on 5050th day when anti-HBs was positive. When anti-HBc IgG-positive cases were analyzed according to their transplantation types, allogeneic HSCT was found to have higher cumulative incidence (45% on 3258th day) for HBV reactivation than autologous HSCT (7% on 5050th day). Besides, HBV reactivation in anti-HBc IgG-positive patients who received allogeneic transplantation was related to mortality. Findings of this study suggest that HBV prophylaxis extending over 1 year should be prescribed for HBsAg-positive patients independent of the transplantation type. Prophylaxis should also be given to anti-HBc IgG-positive patients if an allogeneic HSCT is to be performed.

Brazilian Nutritional Consensus in Hematopoietic Stem Cell Transplantation: Adults

The nutritional status of patients submitted to hematopoietic stem cell transplant is considered an independent risk factor, which may influence on quality of life and tolerance to the proposed treatment. The impairment of nutritional status during hematopoietic stem cell transplant occurs mainly due to the adverse effects resulting from conditioning to which the patient is subjected. Therefore, adequate nutritional evaluation and follow-up during hematopoietic stem cell transplant are essential. To emphasize the importance of nutritional status and body composition during treatment, as well as the main characteristics related to the nutritional assessment of the patient, the Brazilian Consensus on Nutrition in Hematopoietic Stem Cell Transplant: Adults was prepared, aiming to standardize and update Nutritional Therapy in this area. Dietitians, nutrition physicians and hematologists from 15 Brazilian centers thar are references in hematopoietic stem cell transplant took part.

Revisiting Role of Vaccinations in Donors, Transplant Recipients, Immunocompromised Hosts, Travelers, and Household Contacts of Stem Cell Transplant Recipients

Vaccination is an effective strategy to prevent infections in immunocompromised hematopoietic stem cell transplant recipients. Pretransplant vaccination of influenza, pneumococcus, Haemophilus influenza type b, diphtheria, tetanus, and hepatitis B, both in donors and transplant recipients, produces high antibody titers in patients compared with recipient vaccination only. Because transplant recipients are immunocompromised, live vaccines should be avoided with few exceptions. Transplant recipients should get inactive vaccinations when possible to prevent infection. This includes vaccination against influenza, pneumococcus, H. influenza type b, diphtheria, tetanus, pertussis, meningococcus, measles, mumps, rubella, polio, hepatitis A, human papillomavirus, and hepatitis B. Close contacts of transplant recipients can safely get vaccinations (inactive and few live vaccines) as per their need and schedule. Transplant recipients who wish to travel may need to get vaccinated against endemic diseases that are prevalent in such areas. There is paucity of data on the role of vaccinations for patients receiving novel immunotherapy such as bispecific antibodies and chimeric antigen receptor T cells despite data on prolonged B cell depletion and higher risk of opportunistic infections.

Effect of Recombinant Zoster Vaccine on Incidence of Herpes Zoster After Autologous Stem Cell Transplantation: A Randomized Clinical Trial

IMPORTANCE

Herpes zoster, a frequent complication following autologous hematopoietic stem cell transplantation (HSCT), is associated with significant morbidity. A nonlive adjuvanted recombinant zoster vaccine has been developed to prevent posttransplantation zoster.

OBJECTIVE

To assess the efficacy and adverse event profile of the recombinant zoster vaccine in immunocompromised autologous HSCT recipients.

DESIGN, SETTING, AND PARTICIPANTS

Phase 3, randomized, observer-blinded study conducted in 167 centers in 28 countries between July 13, 2012, and February 1, 2017, among 1846 patients aged 18 years or older who had undergone recent autologous HSCT.

INTERVENTIONS

Participants were randomized to receive 2 doses of either recombinant zoster vaccine (n = 922) or placebo (n = 924) administered into the deltoid muscle; the first dose was given 50 to 70 days after transplantation and the second dose 1 to 2 months thereafter.

MAIN OUTCOMES AND MEASURES

The primary end point was occurrence of confirmed herpes zoster cases.

RESULTS

Among 1846 autologous HSCT recipients (mean age, 55 years; 688 [37%] women) who received 1 vaccine or placebo dose, 1735 (94%) received a second dose and 1366 (74%) completed the study. During the 21-month median follow-up, at least 1 herpes zoster episode was confirmed in 49 vaccine and 135 placebo recipients (incidence, 30 and 94 per 1000 person-years, respectively), an incidence rate ratio (IRR) of 0.32 (95% CI, 0.22-0.44; P < .001), equivalent to 68.2% vaccine efficacy. Of 8 secondary end points, 3 showed significant reductions in incidence of postherpetic neuralgia (vaccine, n=1; placebo, n=9; IRR, 0.1; 95% CI, 0.00-0.78; P = .02) and of other prespecified herpes zoster-related complications (vaccine, n=3; placebo, n=13; IRR, 0.22; 95% CI, 0.04-0.81; P = .02) and in duration of severe worst herpes zoster-associated pain (vaccine, 892.0 days; placebo, 6275.0 days; hazard ratio, 0.62; 95% CI, 0.42-0.89; P = .01). Five secondary objectives were descriptive. Injection site reactions were recorded in 86% of vaccine and 10% of placebo recipients, of which pain was the most common, occurring in 84% of vaccine recipients (grade 3: 11%). Unsolicited and serious adverse events, potentially immune-mediated diseases, and underlying disease relapses were similar between groups at all time points.

CONCLUSIONS AND RELEVANCE

Among adults who had undergone autologous HSCT, a 2-dose course of recombinant zoster vaccine compared with placebo significantly reduced the incidence of herpes zoster over a median follow-up of 21 months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01610414.

Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Infection is a main concern after haemopoietic stem cell transplantation (HSCT) and a major cause of transplant-related mortality. Some of these infections are preventable by vaccination. Most HSCT recipients lose their immunity to various pathogens as soon as the first months after transplant, irrespective of the pre-transplant donor or recipient vaccinations. Vaccination with inactivated vaccines is safe after transplantation and is an effective way to reinstate protection from various pathogens (eg, influenza virus and Streptococcus pneumoniae), especially for pathogens whose risk of infection is increased by the transplant procedure. The response to vaccines in patients with transplants is usually lower than that in healthy individuals of the same age during the first months or years after transplant, but it improves over time to become close to normal 2-3 years after the procedure. However, because immunogenic vaccines have been found to induce a response in a substantial proportion of the patients as early as 3 months after transplant, we recommend to start crucial vaccinations with inactivated vaccines from 3 months after transplant, irrespectively of whether the patient has or has not developed graft-versus-host disease (GvHD) or received immunosuppressants. Patients with GvHD have higher risk of infection and are likely to benefit from vaccination. Another challenge is to provide HSCT recipients the same level of vaccine protection as healthy individuals of the same age in a given country. The use of live attenuated vaccines should be limited to specific situations because of the risk of vaccine-induced disease.

Reactivation of hepatitis B virus infection in patients with hematologic disorders

Hepatitis B reactivation is the reappearance or rise of hepatitis B virus (HBV) DNA in patients with past or chronic HBV infection, usually occurring in the context of immunosuppression. HBV reactivation has been most commonly reported in patients with hematologic disorders, with potentially serious and life-threatening consequences. In this review, we discuss the basis and presentation of HBV reactivation, and risk factors in terms of the host, the virus and the immunosuppression regimen, including newer agents used to manage hematologic malignancies. We overview the management of HBV reactivation, highlighting an up-dated recommendation on the use of newer nucleoside and nucleotide analogs, such as tenofovir and entecavir, for antiviral prophylaxis.

A comparison of viral microneutralization and haemagglutination inhibition assays as measures of seasonal inactivated influenza vaccine immunogenicity in the first year after reduced intensity conditioning, lymphocyte depleted allogeneic haematopoietic stem cell transplant

Traditionally, immune response to influenza vaccines has been measured using the haemagglutination inhibition (HAI) assay. A broader repertoire of techniques including the sensitive viral microneutralization (VMN) assay is now recommended by the European Medicines Agency (EMA). Comparing HAI and VMN, we determined immune response to a trivalent 2015-2016 seasonal inactivated influenza vaccine (SIIV) administered to 28 recipients of allogeneic haematopoietic stem cell transplant (HSCT). Vaccination was within the first-year post-transplant at a median of 78.5 (24-363) days. The proportion of patients with baseline and post-vaccination HAI titres ≥ 1:40 were 28.6% and 25% for A(H1N1)pdm09, 14.3% at both timepoints for A(H3N2), and 32.1% and 25% for B(Phuket). Pre and Post-vaccination geometric mean titres(GMT) were higher by VMN than HAI for A(H1N1)pdm09 and A(H3N2), but lower for B(Phuket)(p=<0.05). Geometric mean ratios(GMR) of baseline and post-vaccination titres were similar by HAI and VMN(p > 0.05) for all components. A single seroconversion to A(H1N1) was detected by ELISA-VMN. None of patient age, lymphocyte count, days from transplant to vaccination, donor type, or graft-versus-host disease (GVHD) or immunosuppressive therapy (IST) at vaccination correlated with baseline or post-vaccination titres by either assay. This absence of seroresponse to SIIV in the first-year post HSCT highlights the need for novel immunogenic vaccination formulations and schedules in this high-risk population.

Vaccinating donors for hematopoietic cell transplantation: A systematic review and future perspectives

Allogeneic hematopoietic cell transplantation (Allo-HCT) recipients are at an increased risk of infectious complications, which is a major cause of morbidity and mortality post-transplant. Vaccination of donors is one of the strategies that has been studied to improve immune reconstitution post-transplant, however the efficacy and safety of this strategy is not well reviewed in the literature. In this systematic review we sought to evaluate the current strategies of donor vaccination along with their immunogenicity, effectiveness and safety. Utilizing strict selection criteria with defined MeSH terminology, an electronic search was conducted from the following databases: Medline, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Scopus. Abstracts of various professional society meetings were also screened and hand searching of various reviews and guideline articles was carried out. The full text of 52 articles were reviewed, from which 5 articles satisfied the inclusion/exclusion criteria for effectiveness and immunogenicity trials and 1 article was included for safety data. Jadad score was used to assess the quality of included studies. The results of the included studies were inconsistent, and the studies were generally of suboptimal methodological quality. Most of the included studies (n = 3) investigated the use of more than one vaccine, however not all commonly used vaccines in HCT were investigated. None of the studies reported any long-term benefits for HCT recipients of vaccinated donors. Only one study reported safety data of using vaccination in donors. Given the suboptimal quality of the studies, and questionable effectiveness, donor vaccination cannot be recommended for all. Prospective high-quality vaccine trials in HCT donors are needed.

Adherence and immune response to revaccination following hematopoietic stem cell transplantation at a pediatric onco-hematology reference center

BACKGROUND

Revaccination after hematopoietic stem cell transplantation (HSCT) is necessary to compensate for the loss of immunological memory. The aims of this study were to evaluate the adherence to revaccination schedule and the humoral immune response to different vaccine antigens in HSCT pediatric and young adult patients.

METHODS

Patients submitted to HSCT for over 3 years were recruited. After written informed consent, a questionnaire was filled in, the vaccination card was analyzed, a blood sample was collected and tested by ELISA for diphtheria, Haemophilus influenzae type b (Hib), hepatitis A, hepatitis B, tetanus, measles, rubella, and varicella antibodies.

RESULTS

Sixty-three patients (mean age at HSCT, 10.7 years) were evaluated. Forty-one (65%) were male; 34 (54%) had allogeneic and 29 (46%), autologous HSCT. Complete adherence to diphtheria revaccination was found in 79.4% patients and seropositivity was found in 92% of those who completed the revaccination schedule; for Hib, 68.3% adherence and 95.3% seropositivity were observed; for hepatitis A, 63.5% adherence and 92.5% seropositivity; for 3 doses of hepatitis B, 86.8% adherence and 79.2% seropositivity; for tetanus, 79.4% adherence and 100% seropositivity; for measles and rubella, 17.5% adherence and 100% seropositivity; for varicella, 7.9% adherence and 100% seropositivity. The existence of a Vaccination Center for Special Immunobiologicals in patients' municipality was positively associated with completed vaccine schedule; on the other hand, chronic GVHD was negatively associated with revaccination adherence.

CONCLUSION

Hematopoietic stem cell transplantation patients showed good seropositivity rates after complete vaccination schedule. However, a low coverage rate was observed for live attenuated antigens.

CMV-specific immune reconstitution following allogeneic stem cell transplantation

Cytomegalovirus (CMV) remains a major contributor to morbidity and mortality following allogeneic haemopoietic stem cell transplant (HSCT) despite widespread use of viraemia monitoring and pre-emptive antiviral therapy. Uncontrolled viral replication occurs primarily in the first 100 d post transplant but this high risk period can extend to many months if immune recovery is delayed. The re-establishment of a functional population of cellular effectors is essential for control of virus replication and depends on recipient and donor serostatus, the stem cell source, degree of HLA matching and post-transplant factors such as CMV antigen exposure, presence of GVHD and ongoing use of immune suppression. A number of immune monitoring assays exist but have not yet become widely accessible for routine clinical use. Vaccination, adoptive transfer of CMV specific T cells and a number of graft engineering processes are being evaluated to enhance of CMV specific immune recovery post HSCT.

Vaccinations in patients with hematological malignancies

Patients with hematological malignancies are at risk for a number of infections that are potentially preventable by vaccinations such as pneumococcal infections and influenza. Treatment, especially with anti-B-cell antibodies and hematopoietic stem cell transplantation (HSCT), negatively impacts the response to vaccination for several months. It is therefore recommended that patients be vaccinated before initiating immunosuppressive therapy if possible. The risk of side-effects with inactivated vaccines is low, but care has to be taken with live vaccines, such as varicella-zoster virus vaccine, since severe and fatal complications have been reported. HSCT patients require repeated doses of most vaccines to achieve long-lasting immune responses. New therapeutic options for patients with hematological malignancies that are rapidly being introduced into clinical practice will require additional research regarding the efficacy of vaccinations. New vaccines are also in development that will require well-designed studies to ascertain efficacy and safety.