Applicability of probabilistic graphical models for early detection of SARS-CoV-2 reactive antibodies after SARS-CoV-2 vaccination in hematological patients.

Prior studies of antibody response after full SARS-CoV-2 vaccination in hematological patients have confirmed lower antibody levels compared to the general population. Serological response in hematological patients varies widely according to the disease type and its status, and the treatment given and its timing with respect to vaccination. Through probabilistic machine learning graphical models, we estimated the conditional probabilities of having detectable anti-SARS-CoV-2 antibodies at 3-6 weeks after SARS-CoV-2 vaccination in a large cohort of patients with several hematological diseases (n= 1166). Most patients received mRNA-based vaccines (97%), mainly Moderna® mRNA-1273 (74%) followed by Pfizer-BioNTech® BNT162b2 (23%). The overall antibody detection rate at 3 to 6 weeks after full vaccination for the entire cohort was 79%. Variables such as type of disease, timing of anti-CD20 monoclonal antibody therapy, age, corticosteroids therapy, vaccine type, disease status, or prior infection with SARS-CoV-2 are among the most relevant conditions influencing SARS-CoV-2-IgG-reactive antibody detection. A lower probability of having detectable antibodies was observed in patients with B-cell non-Hodgkin's lymphoma treated with anti-CD20 monoclonal antibodies within 6 months before vaccination (29.32%), whereas the highest probability was observed in younger patients with chronic myeloproliferative neoplasms (99.53%). The Moderna® mRNA-1273 compound provided higher probabilities of antibody detection in all scenarios. This study depicts conditional probabilities of having detectable antibodies in the whole cohort and in specific scenarios such as B cell NHL, CLL, MM, and cMPN that may impact humoral responses. These results could be useful to focus on additional preventive and/or monitoring interventions in these highly immunosuppressed hematological patients.

SARS-CoV-2-reactive antibody detection after SARS-CoV-2 vaccination in hematopoietic stem cell transplant recipients: Prospective survey from the Spanish Hematopoietic Stem Cell Transplantation and Cell Therapy Group.

This is a multicenter prospective observational study that included a large cohort (n = 397) of allogeneic (allo-HSCT; (n = 311) and autologous (ASCT) hematopoietic stem cell transplant (n = 86) recipients who were monitored for antibody detection within 3-6 weeks after complete severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination from February 1, 2021, to July 20, 2021. Most patients (n = 387, 97.4%) received mRNA-based vaccines. Most of the recipients (93%) were vaccinated more than 1 year after transplant. Detectable SARS-CoV-2-reactive antibodies were observed in 242 (78%) of allo-HSCT and in 73 (85%) of ASCT recipients. Multivariate analysis in allo-HSCT recipients identified lymphopenia < 1 × 109 /ml (odds ratio [OR] 0.33, 95% confidence interval [95% CI] 0.16-0.69, p = .003), active graft versus host disease (GvHD; OR 0.51, 95% CI 0.27-0.98, p = .04) and vaccination within the first year of transplant (OR 0.3, 95% CI 0.15-0.9, p = .04) associated with lower antibody detection whereas. In ASCT, non-Hodgkin's lymphoma (NHL; OR 0.09, 95% CI 0.02-0.44, p = .003) and active corticosteroid therapy (OR 0.2, 95% CI 0.02-0.87, p = .03) were associated with lower detection rate. We report an encouraging rate of SARS-CoV-2-reactive antibodies detection in these severe immunocompromised patients. Lymphopenia, GvHD, the timing of vaccine, and NHL and corticosteroids therapy should be considered in allo-HSCT and ASCT, respectively, to identify candidates for SARS-CoV-2 antibodies monitoring.

Maintenance therapy with ex vivo expanded lymphokine-activated killer cells and rituximab in patients with follicular lymphoma is safe and may delay disease progression.

Anti-cluster of differentiation 20 (CD20) monoclonal antibodies (mAbs) have shown promise in follicular lymphoma (FL) as post-induction therapy, by enhancing antibody-dependent cellular cytotoxicity (ADCC). However, cytotoxic cells are reduced after this treatment. We hypothesised that ex vivo expanded lymphokine-activated killer (LAK) cells administered to FL-remission patients are safe and improve anti-CD20 efficacy. This open, prospective, phase II, single-arm study assessed safety and efficacy of ex vivo expanded LAK cells in 20 FL-remission patients following rituximab maintenance. Mononuclear cells were obtained in odd rituximab cycles and stimulated with interleukin 2 (IL-2) for 8 weeks, after which >5 × 108 LAK cells were injected. Patients were followed-up for 5 years. At the end of maintenance, peripheral blood cells phenotype had not changed markedly. Natural killer, LAK and ADCC activities of mononuclear cells increased significantly after recombinant human IL-2 (rhIL-2) stimulation in all cycles. Rituximab significantly enhanced cytotoxic activity. No patients discontinued treatment. There were no treatment-related serious adverse events. Three patients had progressed by the end of follow-up. After a median (interquartile range) follow-up of 59.4 (43.8-70.9) months, 85% of patients remained progression free. No deaths occurred. Quality-of-life improved throughout the study. Post-induction LAK cells with rituximab seem safe in the long term. Larger studies are warranted to confirm efficacy.

One-year breakthrough SARS-CoV-2 infection and correlates of protection in fully vaccinated hematological patients.

The long-term clinical efficacy of SARS-CoV-2 vaccines according to antibody response in immunosuppressed patients such as hematological patients has been little explored. A prospective multicenter registry-based cohort study conducted from December 2020 to July 2022 by the Spanish Transplant and Cell Therapy group, was used to analyze the relationship of antibody response over time after full vaccination (at 3-6 weeks, 3, 6 and 12 months) (2 doses) and of booster doses with breakthrough SARS-CoV-2 infection in 1551 patients with hematological disorders. At a median follow-up of 388 days after complete immunization, 266 out of 1551 (17%) developed breakthrough SARS-CoV-2 infection at median of 86 days (range 7-391) after full vaccination. The cumulative incidence was 18% [95% confidence interval (C.I.), 16-20%]. Multivariate analysis identified higher incidence in chronic lymphocytic leukemia patients (29%) and with the use of corticosteroids (24.5%), whereas female sex (15.5%) and more than 1 year after last therapy (14%) were associated with a lower incidence (p < 0.05 for all comparisons). Median antibody titers at different time points were significantly lower in breakthrough cases than in non-cases. A serological titer cut-off of 250 BAU/mL was predictive of breakthrough infection and its severity. SARS-CoV-2 infection-related mortality was encouragingly low (1.9%) in our series. Our study describes the incidence of and risk factors for COVID-19 breakthrough infections during the initial vaccination and booster doses in the 2021 to mid-2022 period. The level of antibody titers at any time after 2-dose vaccination is strongly linked with protection against both breakthrough infection and severe disease, even with the Omicron SARS-CoV-2 variant.

SARS-CoV-2-reactive antibody waning, booster effect and breakthrough SARS-CoV-2 infection in hematopoietic stem cell transplant and cell therapy recipients at one year after vaccination.

The kinetics of SARS-CoV-2 reactive IgG antibodies after full vaccination and booster in allogeneic and autologous stem cell transplantation (allo-HSCT, ASCT) and chimeric antigen receptor T-cell therapy (CAR-T) are of utmost importance for estimating risk of infection. A prospective multicenter registry-based cohort study, conducted from December 2020 to July 2022 was used to analyze antibody waning over time, booster effect and the relationship of antibody response and breakthrough infection in 572 recipients (429 allo-HSCT, 121 ASCT and 22 CAR-T cell therapy). A significant decline in antibody titers was observed at 3 and 6 months after full vaccination in recipients without pre-vaccine SARS-CoV-2 infection, whereas recipients infected prior to vaccination showed higher and stable antibody titers over time. In poor responders, a booster dose was able to increase antibody titers in 83% of allo-HSCT and 58% of ASCT recipients but not in CART-T cell recipients [0%] (p < 0.01). One-year cumulative incidence of breakthrough infection was 15%, similar among cell therapy procedures. Immunosuppressive drugs at the time of vaccination [hazard ratio (HR) 1.81, p = 0.0028] and reduced intensity conditioning (HR 0.49, p = 0.011) were identified as the only conditions associated with different risk of breakthrough infection in allo-HSCT recipients. Antibody titers were associated with breakthrough infection and disease severity. No death was observed among the 72 breakthrough infections. Antibody level decay after the first two vaccine doses was common except in recipients with pre-vaccination SARS-CoV-2 infection. Poorly responding allo-HSCT recipients showed a response advantage with the booster as compared to ASCT and, especially, the null response found in CAR-T cell recipients. Antibody titers were positively correlated with the risk of breakthrough SARS-CoV-2 infection which was mainly driven by the immunosuppression status.

SARS-CoV-2 vaccine response and rate of breakthrough infection in patients with hematological disorders.

BACKGROUND: The clinical efficacy of SARS-CoV-2 vaccines according to antibody response in immunosuppressed patients such as hematological patients has not yet been established. PATIENTS AND METHODS: A prospective multicenter registry-based cohort study conducted from December 2020 to December 2021 by the Spanish transplant and cell therapy group was used to analyze the relationship of antibody response at 3-6 weeks after full vaccination (2 doses) with breakthrough SARS-CoV-2 infection in 1394 patients with hematological disorders. RESULTS: At a median follow-up of 165 days after complete immunization, 37 out of 1394 (2.6%) developed breakthrough SARS-CoV-2 infection at median of 77 days (range 7-195) after full vaccination. The incidence rate was 6.39 per 100 persons-year. Most patients were asymptomatic (19/37, 51.4%), whereas only 19% developed pneumonia. The mortality rate was 8%. Lack of detectable antibodies at 3-6 weeks after full vaccination was the only variable associated with breakthrough infection in multivariate logistic regression analysis (Odds Ratio 2.35, 95% confidence interval 1.2-4.6, p = 0.012). Median antibody titers were lower in cases than in non-cases [1.83 binding antibody units (BAU)/mL (range 0-4854.93) vs 730.81 BAU/mL (range 0-56,800), respectively (p = 0.007)]. We identified 250 BAU/mL as a cutoff above which incidence and severity of the infection were significantly lower. CONCLUSIONS: Our study highlights the benefit of developing an antibody response in these highly immunosuppressed patients. Level of antibody titers at 3 to 6 weeks after 2-dose vaccination links with protection against both breakthrough infection and severe disease for non-Omicron SARS-CoV-2 variants.

Prognostic significance of FLT3-ITD length in AML patients treated with intensive regimens.

FLT3-ITD mutations are detected in approximately 25% of newly diagnosed adult acute myeloid leukemia (AML) patients and confer an adverse prognosis. The FLT3-ITD allelic ratio has clear prognostic value. Nevertheless, there are numerous manuscripts with contradictory results regarding the prognostic relevance of the length and insertion site (IS) of the FLT3-ITD fragment. We aimed to assess the prognostic impact of these variables on the complete remission (CR) rates, overall survival (OS) and relapse-free survival (RFS) of AML patients with FLT3-ITDmutations. We studied the FLT3-ITD length of 362 adult AML patients included in the PETHEMA AML registry. We tried to validate the thresholds of ITD length previously published (i.e., 39 bp and 70 bp) in intensively treated AML patients (n = 161). We also analyzed the mutational profile of 118 FLT3-ITD AML patients with an NGS panel of 39 genes and correlated mutational status with the length and IS of ITD. The AUC of the ROC curve of the ITD length for OS prediction was 0.504, and no differences were found when applying any of the thresholds for OS, RFS or CR rate. Only four out of 106 patients had ITD IS in the TKD1 domain. Our results, alongside previous publications, confirm that FLT3-ITD length lacks prognostic value and clinical applicability.