CD154 expression is associated with neutralizing antibody titer levels postinfluenza vaccination in stem cell transplant patients and healthy adults

Influenza vaccines in immunosuppressed adults with cancer

BACKGROUND

This is an update of the Cochrane review published in 2013, Issue 10.Immunosuppressed cancer patients are at increased risk of serious influenza-related complications. Guidelines, therefore, recommend influenza vaccination for these patients. However, data on vaccine effectiveness in this population are lacking, and the value of vaccination in this population remains unclear.

OBJECTIVES

To assess the effectiveness of influenza vaccine in immunosuppressed adults with malignancies. The primary review outcome is all-cause mortality, preferably at the end of the influenza season. Influenza-like illness (ILI, a clinical definition), confirmed influenza, pneumonia, any hospitalisations, influenza-related mortality and immunogenicity were defined as secondary outcomes.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and LILACS databases up to May 2017. We searched the following conference proceedings: ICAAC, ECCMID, IDSA (infectious disease conferences), ASH, ASBMT, EBMT (haematological), and ASCO (oncological) between the years 2006 to 2017. In addition, we scanned the references of all identified studies and pertinent reviews. We searched the websites of the manufacturers of influenza vaccine. Finally, we searched for ongoing or unpublished trials in clinical trial registry databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs), prospective and retrospective cohort studies and case-control studies were considered, comparing inactivated influenza vaccines versus placebo, no vaccination or a different vaccine, in adults (16 years and over) with cancer. We considered solid malignancies treated with chemotherapy, haematological cancer patients treated or not treated with chemotherapy, cancer patients post-autologous (up to six months after transplantation) or allogeneic (at any time) haematopoietic stem cell transplantation (HSCT).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from included studies adhering to Cochrane methodology. Meta-analysis could not be performed because of different outcome and denominator definitions in the included studies.

MAIN RESULTS

We identified six studies with a total of 2275 participants: five studies comparing vaccination with no vaccination, and one comparing adjuvanted vaccine with non-adjuvanted vaccine. Three studies were RCTs, one was a prospective observational cohort study and two were retrospective cohort studies.For the comparison of vaccination with no vaccination we included two RCTs and three observational studies, including 2202 participants. One study reported results in person-years while the others reported results per person. The five studies were performed between 1993 and 2015 and included adults with haematological diseases (three studies), patients following bone marrow transplantation (BMT) (two studies) and solid malignancies (three studies).One RCT and two observational studies reported all-cause mortality; the RCT showed similar mortality rates in both arms (odds ratio (OR) 1.25 (95% CI 0.43 to 3.62; 1 study, 78 participants, low-certainty evidence)); and the observational studies demonstrated a significant association between vaccine receipt and lower risk of death, adjusted hazard ratio 0.88 (95% CI 0.78 to 1; 1 study, 1577 participants, very low-certainty evidence) in one study and OR 0.42 (95% CI 0.24 to 0.75; 1 study, 806 participants, very low-certainty evidence) in the other. One RCT reported a reduction in ILI with vaccination, while no difference was observed in one observational study. Confirmed influenza rates were lower with vaccination in one RCT and the three observational studies, the difference reaching statistical significance in one. Pneumonia was observed significantly less frequently with vaccination in one observational study, but no difference was detected in another or in the RCT. One RCT showed a reduction in hospitalisations following vaccination, while an observational study found no difference. No life-threatening or persistent adverse effects from vaccination were reported. The strength of evidence was limited by the low number of included studies and by their low methodological quality and the certainty of the evidence for the mortality outcome according to GRADE was low to very low.For the comparison of adjuvanted vaccine with non-adjuvanted vaccine, we identified one RCT, including 73 patients. No differences were found for the primary and all secondary outcomes assessed. Mortality risk ratio was 0.54 (95% CI 0.05 to 5.73; low-certainty evidence) in the adjuvanted vaccine group. The quality of evidence was low due to the small sample size and the large confidence intervals for all outcomes.

AUTHORS' CONCLUSIONS

Observational data suggest lower mortality and infection-related outcomes with influenza vaccination. The strength of evidence is limited by the small number of studies and low grade of evidence. It seems that the evidence, although weak, shows that the benefits overweigh the potential risks when vaccinating adults with cancer against influenza. However, additional placebo or no-treatment controlled RCTs of influenza vaccination among adults with cancer is ethically questionable.There is no conclusive evidence regarding the use of adjuvanted versus non-adjuvanted influenza vaccine in this population.

Immune reconstitution after hematopoietic cell transplantation

PURPOSE OF REVIEW

Successful immune reconstitution is important for decreasing posthematopoietic cell transplant (post-HCT) infections, relapse, and secondary malignancy, without increasing graft-versus-host disease (GVHD). Here we review how different parts of the immune system recover, and the relationship between recovery and clinical outcomes.

RECENT FINDINGS

Innate immunity (e.g., neutrophils, natural killer cells) recovers within weeks, whereas adaptive immunity (B and T cells) recovers within months to years. This has been known for years; however, more recently, the pattern of recovery of additional immune cell subsets has been described. The role of these subsets in transplant complications like infections, GVHD and relapse is becoming increasingly recognized, as gleaned from studies of the association between subset counts or function and complications/outcomes, and from studies depleting or adoptively transferring various subsets.

SUMMARY

Lessons learned from observational studies on immune reconstitution are leading to new strategies to prevent or treat posttransplant infections. Additional knowledge is needed to develop effective strategies to prevent or treat relapse, second malignancies and GVHD.

In vitro generation of influenza-specific polyfunctional CD4+ T cells suitable for adoptive immunotherapy

BACKGROUND AIMS

Influenza viruses cause potentially fatal respiratory infections in stem cell transplant patients. Specific T cells provide long-lived host adaptive immunity to influenza viruses, and the potential for generating such cells for clinical use was investigated.

METHODS

The inactivated influenza vaccine (Fluvax) approved for human use was used as the antigen source. Monocyte-derived dendritic cells pulsed with Fluvax were used to stimulate autologous peripheral blood mononuclear cells (PBMC) on days 0 and 7. Cells were expanded with interleukin (IL)-2 from day 7 onwards. Cell numbers and phenotype were assessed on day 21. The presence of influenza virus-specific cells was assessed by cytokine production and proliferative responses following restimulation with influenza antigens.

RESULTS

Over 21 days of culture, a mean fold increase of 26.3 in cell number was observed (n = 7). Cultures were predominantly effector and central memory CD4+ cells, and expressed a phenotype characteristic of activated antigen-specific cells capable of B-cell helper function. Cytotoxic CD4+ and CD8+ cells specific for influenza and a high percentage of CD4+ cells specific for each of three influenza viruses targeted by Fluvax (H1N1, H3N2 and Brisbane viruses) were generated. In addition, T cells expanded when restimulated with antigens derived from influenza viruses.

CONCLUSIONS

We have demonstrated a clinically usable method for producing influenza virus-specific T cells that yield high numbers of highly reactive CD4+ cells suitable for adoptive immunotherapy. We propose that reconstructing host immunity through adoptive transfer of influenza virus-specific T cells will reduce the frequency of influenza-related deaths in the period of severe immune suppression that follows stem cell transplantation.