Determinants of CD19-positive vs CD19-negative relapse after tisagenlecleucel for B-cell acute lymphoblastic leukemia.

Tisagenlecleucel therapy has shown promising efficacy for relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, relapses occur in 30-50% of patients. Determinants for CD19pos versus CD19neg relapses are poorly characterized. We report on 51 patients with R/R BCP-ALL (median age 17 years) infused with tisagenlecleucel after lymphodepletion. Complete remission rate at D28 was 96%. Prior blinatumomab increased the risk of early failure at D28. The 18-month cumulative incidence of relapse (CIR), event-free survival (EFS), and overall survival (OS) were 51%, 44%, and 74%, respectively, at a median follow-up of 15.5 months. Factors associated with a high tumor burden (occurrence of cytokine release syndrome) and prior blinatumomab were associated with an increased CIR, and a shorter EFS and OS. Pre-lymphodepletion high disease burden (MRD ≥ 10-2, SHR 10.4, p = 0.03) and detectable MRD at D28 (SHR 7.2, p = 0.006) correlated with an increased risk of CD19neg relapse. Low disease burden (SHR 5.3, p = 0.03) and loss of B-cell aplasia (BCA) (SHR 21.7, p = 0.004) predicted an increased risk of CD19pos relapses. These data highlight the impact of prior therapy on patient outcome. Finally, detectable MRD at D28 and loss of BCA both define patients at high risk of relapse for whom additional interventions are needed.

Relationship between cytomegalovirus (CMV) reactivation, CMV-driven immunity, overall immune recovery and graft-versus-leukaemia effect in children.

The interplay between immune recovery, cytomegalovirus (CMV)-reactivation, CMV-driven immunity and graft-versus-leukaemia effect (GVL) was analysed in 108 children (median age: 8 years) who underwent haematopoietic-stem cell transplantation (HSCT) for acute leukaemia. Follow-up was 2 years unless death or relapse occurred. CMV-polymerase chain reaction (PCR) was programmed weekly until month +3 post-HSCT. Immunomonitoring consisted of sequential lymphocyte subset enumerations and analyses of T-cell proliferative and γ-interferon responses to CMV and to adenovirus. In the 108 recipients, the 2-year relapse rate (RR) was 25% (median time to onset 4·5 months; range: 24 d-17 months). CMV reactivation occurrence was 31% (median time to onset 26 d). Donor/recipient CMV serostatus did not influence RR. Among the 89 recipients disease-free after day +120, i) early CMV-reactivation before day +30 was more frequent (P = 0·01) in the relapse recipient group opposed to the non-relapse group. ii) CD8(+) /CD28(-) and CD4(+) CD45RA(-) T-cell expansions induced by CMV did not influence RR, iii) Recovery of anti-CMV and also anti-adenovirus immunity and of naïve CD4(+) T-cells was faster in the non-relapse group (P = 0·008; 0·009 and 0·002 respectively). In contrast to adult acute myeloid leukaemia, CMV reactivation was associated with increased RR in this paediatric series. Accelerated overall immune recovery rather than CMV-driven immunity had a favourable impact on RR.

Cellular and humoral immunity elicited by influenza vaccines in pediatric hematopoietic-stem cell transplantation.

Immunity induced by influenza vaccines following hematopoietic stem-cell transplantation (HSCT) is poorly understood. Here, 14 pediatric recipients (mean age: 6 years) received H1N1 (n=9) or H1N1/H3N2 (n=5) vaccines at a median of 5.7 months post-HSCT (HLA-identical related bone-marrow graft: 10/14). Fourteen clinically-matched non-vaccinated recipients were included as controls. Cellular response to vaccination was assessed by a T-cell proliferation assay. Humoral response was assessed by H1N1-specific antibody titration. IL2 and IFNγ responses to influenza were also evaluated by an intracellular cytokine accumulation method for some of the recipients. Higher proliferative responses to H1N1 (p=0.0001) and higher H1N1-specific antibody titers (p<0.02) were observed in vaccines opposed to non-vaccinated recipients. In some cases, proliferative responses to H1N1 developed while at the same time antibody titers did not reach protective (≥1:40) levels. Most recipients vaccinated with only the H1N1 strain had proliferative responses to both H1N1 and H3N2 (median stimulation index H1N1: 96, H3N2: 126 in responders). Finally, IL2 responses predominated over IFNγ responses (p<0.02) to influenza viruses in responders. In conclusion, H1N1 vaccination induced substantial cell-mediated immunity, and to a lesser extent, humoral immunity at early times post-HSCT. H1N1/H3N2 T-cell cross-reactivity and protective (IL2) rather than effector (IFNγ) cytokinic profiles were elicited.

TNF-α/IL-2 ratio discriminates latent from active tuberculosis in immunocompetent children: a pilot study.

BACKGROUND: Distinguishing latent tuberculosis (LTB) from tuberculosis (TB) disease may be challenging in children. Here, we analyzed cytokine profiles that can distinguish the two infection stages in a nonendemic country (France). METHODS: Immunocompetent children with LTB (n = 6) or TB disease (n = 8) (median age: 6.2 and 5.7 years, respectively) were analyzed. Four young uninfected children were included as controls. A Luminex assay evaluated cytokine responses to Mycobacterium tuberculosis antigens. RESULTS: Poor interleukin-4 (IL-4) and IL-10 responses precluded analysis of these cytokines. Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-2, and T-helper type 1 (Th1) cytokines and IL-5, IL-13, T-helper type 2 (Th2) cytokines were simultaneously induced by antigens in 14/14 infected but 0/4 uninfected children. Th1 cytokine levels were similar in LTB and TB disease: IFN-γ: 12,254 and 10,495 pg/ml; IL-2: 2,097 and 1,869 pg/ml; and TNF-α: 1,020 and 2,875 pg/ml, respectively. Th2 cytokine levels were similar and even higher in LTB than in TB disease: IL-5: 23 and 10 pg/ml; IL-13: 284 and 109 pg/ml, respectively. Positive correlation of cytokine levels, whether Th1 or Th2, was observed. Higher (P = 0.008) TNF-α/IL-2 ratios distinguished 6/8 active TB disease cases from 6/6 LTB cases. CONCLUSION: TNF-α/IL-2 ratio may discriminate TB disease from LTB in immunocompetent children. Larger studies in TB endemic settings must verify these results.

Contribution of HLA-A/B/C/DRB1/DQB1 common haplotypes to donor search outcome in unrelated hematopoietic stem cell transplantation.

In unrelated hematopoietic stem cell transplantation (HSCT), the prediction of donor search outcome at the time of search initiation is of great value for the physicians to delineate the strategy of patient care. The probability of finding an unrelated donor is high for patients who carry at least 1 of the 10 most common HLA haplotypes in Caucasians. As only 10% to 20% patients respond to this criterion, here we aimed at finding additional common haplotypes to improve the prediction of a successful search. HLA broad HLA-A/B/DRB1 haplotypes that were observed with frequencies ≥0.19% in patient families of European origin and that split into ≤2 predominant 4-digit HLA-A/B/C/DRB1/DQB1 haplotypes were considered as common. Carriage of at least 1 of those in 168 patients of various geographic areas with no family donor was confronted to the chance of finding ≥9/10 HLA-matched unrelated donors. Fifty common 4-digit haplotypes were identified. A higher (P < 5 × 10(-6)) chance of finding a suitable donor was found for 55 of 170 (32%) recipients that carried at least 1 of these common haplotypes. Up to now, estimates classified patients into ≥3 groups of probability with ≥1 intermediate group of poor utility for the clinicians. Considering carriage of these common haplotypes together with the frequencies of alleles and of B/C and DRB1/DQB1 associations, which are carried by patient HLA haplotypes, we could classify the patients into 2 groups of probability with a 98% and 26% chance of finding a donor, respectively. Prediction of search outcome could be improved by including the 50 most common HLA haplotypes in the current approaches.

Outcome of children treated with haematopoietic-stem cell transplantations from donors expressing the rare C77G variant of the PTPRC (CD45) gene.

The uncommon C77G polymorphism of the Protein-Tyrosine Phosphatase (PTPRC) gene (PTPRC; previously termed CD45) could confer an increased risk of immunopathology. This study compared the outcome of children following human leucocyte antigen-matched unrelated haematopoïetic-stem cell transplantations (HSCT) from donors carrying (C77G cases: n = 8) or not (controls: n = 36) the PTPRC C77G polymorphism. Transmission of the PTPRC C77G polymorphism through the graft was suggested by unusual CD45RA phenotype in the donors and/or in the recipients after, but not before HSCT. Restriction-Fragment Length Polymorphism and sequencing confirmed the polymorphism. Overall survival rates were similar in C77G cases and controls (63% vs. 61%). Acute leukaemia relapse tended to be less frequent in C77G cases (0% vs. 32%; P = 0·09). Among recipients surviving ≥ 30 d, acute GVHD (aGVHD) ≥ grade 2 tended to be more frequent (100% vs. 58%; P = 0·07) and the rate of steroid-refractory or -dependant aGVHD higher (67% vs. 28%) in C77G cases. Finally, extensive chronic GVHD tended to occur more frequently (40% vs. 9%) in C77G cases. Recovery of lymphocyte subsets and virus-specific CD4 was similar in C77G cases and controls while interleukin 2 (IL2)-responses through CD3 stimulation were higher in C77G cases (P = 0·004). In conclusion, HSCT from PTPRC C77G donors could increase GVHD risk without compromising overall survival. Altered IL2-responses could be involved in this process.

Quantitative and qualitative CD4 T cell immune responses related to adenovirus DNAemia in hematopoietic stem cell transplantation.

The nature of adenovirus (AdV)-specific T cells that could best predict the capacity of immunocompromised host to fight AdV is unclear. To this aim, 47 pediatric patients were enrolled for at least 3 months either at allogeneic bone marrow transplantation (BMT) (23 genoidentical, 18 unrelated of which 9 were 10/10 and 9 were 9/10 HLA-matched) or at unrelated cord blood transplantation (n = 6). Enumeration of AdV-specific CD4 T cells secreting cytokines (flow cytometry) and proliferative responses to AdV ((3)HT-incorporation) were compared to AdV-DNAemia. A total of 44/47 patients did not evidence AdV-DNAemia. Thirty-two of 44 (73%) developed CD4-mediated interferon-gamma (IFN-γ) responses to AdV (median 0.36 CD4/µL of blood) since the first month post-HSCT (n = 11: 8 genoidentical and 3 unrelated) or the third month (n = 21 additional patients). At 3 months, both incidence and level intensities of AdV-specific CD4 appeared similar in genoidentical and unrelated BMT (70% and 80%; 0.36 and 0.21 CD4/µL, respectively) and not statistically different from age-matched controls (76%; 1.35 CD4/µL), whereas cord blood transplanted patients exhibited similar incidence but higher level intensities (67%; 1.49 CD4/µL). Polyfunctional (IL2 + IFN-γ) and proliferative responses appeared later, after the third month. Three of 4 9/10 HLA-matched unrelated HSCT that did not develop immunity to AdV presented chemotherapy-resistant AdV-DNAemia at 3 to 5 months post-hematopoietic stem cell transplantation (HSCT). Two were successfully treated with AdV-specific CTL infusion. Monitoring, since month 1 post-HSCT, of IFN-γ-secreting AdV-specific CD4 appears suitable for early detection of at-risk patients especially in 9/10 HLA-matched unrelated HSCT and preferable to monitoring of more delayed IL2- and proliferative responses.