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 CD19
versus CD19
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
, SHR 10.4, p = 0.03) and detectable MRD at D28 (SHR 7.2, p = 0.006) correlated with an increased risk of CD19
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 CD19
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.
The development of cancer and chronic infections is facilitated by many subversion mechanisms, among which enhanced expression of immune checkpoints molecules, such as programmed death-1 (PD-1) and ...cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), on exhausted T cells. Recently, immune checkpoint inhibitors have shown remarkable efficiency in the treatment of a number of cancers. However, expression of immune checkpoints on natural killer (NK) cells and its functional consequences on NK cell effector functions are much less explored. In this review, we focus on the current knowledge on expression of various immune checkpoints in NK cells, how it can alter NK cell-mediated cytotoxicity and cytokine production. Dissecting the role of these inhibitory mechanisms in NK cells is critical for the full understanding of the mode of action of immunotherapies using checkpoint inhibitors in the treatment of cancers and chronic infections.
Mucosal-associated invariant T (MAIT) cells are semi-invariant Vα7.2
CD161
CD4
T cells that recognize microbial riboflavin precursor derivatives such as 5-OP-RU presented by MR1. Human MAIT cells are ...abundant in adult blood, but there are very few in cord blood. We longitudinally studied Vα7.2
CD161
T cell and related subset levels in infancy and after cord blood transplantation. We show that Vα7.2
and Vα7.2
CD161
T cells are generated early during gestation and likely share a common prenatal developmental program. Among cord blood Vα7.2
CD161
T cells, the minority recognizing MR1:5-OP-RU display a TRAV/TRBV repertoire very similar to adult MAIT cells. Within a few weeks of life, only the MR1:5-OP-RU reactive Vα7.2
CD161
T cells acquire a memory phenotype. Only these cells expand to form the adult MAIT pool, diluting out other Vα7.2
CD161
and Vα7.2
CD161
populations, in a process requiring at least 6 years to reach adult levels. Thus, the high clonal size of adult MAIT cells is antigen-driven and likely due to the fine specificity of the TCRαβ chains recognizing MR1-restricted microbial antigens.
Chimeric Antigen Receptor T cells (CAR-T) are an outbreaking treatment option for relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). Cytokine release syndrome (CRS) and immune effector ...cell-associated neurotoxicity syndrome (ICANS) are the most common specific toxicities, while severe neutropenia and infections are often observed as well. From March 2020, early G-CSF prophylaxis at day (D) two post-infusion was systematically proposed. We then compared patients treated before that date who did not receive G-CSF or who received late (after D5) G-CSF as control group. Patients administered with early G-CSF had similar duration of grade 4 neutropenia but significantly decreased incidence of febrile neutropenia (58% versus 81%, p = 0.018). Similar rate of toxicities was observed, including overall and grade 3-4 CRS (p = 0.93 and p = 0.28, respectively), and overall and grade 3-4 ICANS (p = 0.62 and p = 0.88, respectively). We observed no difference in the quality of CAR T-cells expansion (p = 0.79, %Cmax), nor in response rate (best ORR, 57.6% vs 61.8%, p = 0.93), nor survival even in a group of patients adjusted by a propensity score. In conclusion, early G-CSF administration was safe and effective in reducing febrile neutropenia without impact on toxicities nor on anti-lymphoma activity of CAR-T.
Several technical limitations of Luminex single antigen (LSA) assays have been described so far. This study focused on a reactivity pattern observed in many sera that cannot be explained by eplets ...described in the Epitope Registry database and sometimes appearing against a self‐HLA allele or antigen. In most cases, this pattern is revealed by a discrepant result when compared with other assays (Luminex PRA, cell‐binding assays such as flow cytometry cross match, LSA from another manufacturer…). We focus here on the Cw1/12/15 pattern appearing on the LABScreen class I LSA provided by One Lambda. We documented its behavior using this LSA after acid denaturation of the beads, using Lifecodes LSA from Immucor, and adsorption of sera either on spleen mononuclear cells from deceased donors or on single HLA transfected cell clones. We studied 33 sera from different patients positive for the three Cw beads, selected from our routine patients' LSA database. Nine patients had transplants from a Cw12 or Cw15 donor without any pejorative evolution of the graft, nor post‐transplant MFI (mean fluorescence intensity) increase of the Cw1/12/15 beads. A significant increase of MFI was observed after acid denaturation of the LABScreen beads. All sera tested by Lifecodes LSA were negative for these Cw beads. Finally, we found no significant difference of MFI after adsorption on cells from either origin. Therefore, the Cw1/12/15 pattern appears to be a false positive reactivity of the LABScreen single antigen assay.
Associations between HLA genotype and disease susceptibility encompass almost all the classic HLA loci. The level of typing resolution enabling a correct identification of an HLA disease ...susceptibility gene depends on the disease itself and/or on the accumulated knowledge about the molecular involvement of the HLA allele(s) engaged. Therefore, the application of Next Generation Sequencing technologies to HLA disease association, which would improve typing resolution, could prove useful to better understand disease severity. In the present study, we tested a nanopore sequencing approach developed by Omixon Biocomputing Ltd, dedicated to on-demand locus typing for HLA and disease, as an alternative to the conventional widely used sequence specific oligoprobe (SSO) approach. A total of 145 DNA samples used in routine diagnosis by SSO were retrospectively analyzed with nanopore technology, for HLA-A*02 immunotherapy decision for A*29, B*27, B*51, B*57 identification in class I, and DRB1, DQA1, and DQB1 for bullous dermatosis, rheumatoid arthritis, diabetes, and celiac disease requests in class II. Each locus was typed in a separate experiment, except for DQB1 and DQA1, which were analyzed together. Concordance between typings reached 100% for all the loci tested. Ambiguities by nanopore were only found for missing exon coverage. This approach was found to be very well adapted to the routine flow imposed by the SSO technique. This study illustrates the use of the new NanoTYPE MONO kit for single locus HLA sequencing for HLA and disease association diagnosis.
Complement‐mediated interference is a well described phenomenon in single antigen bead (SAB) Luminex assay that leads to falsely low or negative results for anti‐HLA antibody (Ab). In a context of ...high amount of Ab, the enrichment of the Ab around the bead can lead to complement cascade activation and deposition, thereafter impairing Ab detection. EDTA is now routinely used to circumvent this interference. In this report, we attempted to decipher the role of the phycoerythrin (PE) label conjugated to the secondary Ab in this interference. Indeed, PE is a huge molecule (240 kDa) that could participate to limiting access of the conjugate to its Ab target on the bead. To this purpose, 22 sera displaying complement interference without pre‐treatment with EDTA were compared on SAB assay with three detection strategies: the recommended PE‐conjugated secondary Ab (IgGPE), an Alexa Fluor 532‐conjugated Ab (IgGAF) bearing a tiny 724 Da fluorochrome, and a biotinylated Ab followed by PE‐conjugated streptavidin (IgGBiot). Complement interference occurred with the three detection methods, but its depth, defined by the percentage of MFI loss with neat serum, was the highest for IgGPE. Our study highlighted the partial role of the PE fluorochrome in complement interference in SAB assays.
The current practice of HLA genotyping in deceased donors poses challenges due to limited resolution within time constraints. Nevertheless, the assessment of compatibility between anti-HLA sensitized ...recipients and mismatched donors remains a critical medical need, particularly when dealing with allele-specific (second field genotyping level) donor-specific antibodies. In this study, we present a customized protocol based on the NanoTYPE® HLA typing kit, employing the MinION® sequencer, which enables rapid HLA typing of deceased donors within a short timeframe of 3.75 h on average at a three-field resolution with almost no residual ambiguities. Through a prospective real-time analysis of HLA typing in 18 donors, we demonstrated the efficacy and precision of our nanopore-based method in comparison to the conventional approach and without delaying organ allocation. Indeed, this duration was consistent with the deceased donor organ donation procedure leading to organ allocation via the French Biomedicine Agency. The improved resolution achieved with our protocol enhances the security of organ allocation, particularly benefiting highly sensitized recipients who often present intricate HLA antibody profiles. By overcoming technical challenges and providing comprehensive genotyping data, this approach holds the potential to significantly impact deceased donor HLA genotyping, thereby facilitating optimal organ allocation strategies.
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