Determinants of SARS-CoV-2 waning immunity in allogeneic hematopoietic stem cell transplant recipients.

Hematopoietic stem cell transplant (HSCT) recipients are at high-risk for severe COVID-19 and have altered immune responses to vaccination. We sought to evaluate the dynamics of immune response to BNT162b2 mRNA vaccine in HSCT recipients. We systematically proposed vaccination with BNT162b2 to HSCT recipients and gave a third vaccine dose to those showing titers of IgG(S-RBD) below 4160 AU/mL 1 month following the second dose. We then quantified anti-SARS-CoV-2 antibodies dynamics in 133 of these HSCT recipients (88 after two and 45 after three vaccine doses) 6 months after the first vaccine dose. Mean IgG(S-RBD) titer at 6 months was significantly lower than the peak value measured 1 month after a second (p < 0.001) or third (p < 0.01) vaccine dose. IgG(S-RBD) titers at 6 months were strongly correlated to peak values (p < 0.001) and a peak titer above 10,370 AU/mL predicted persistent protection at 6 months. Seventy-two percent (96/133) of patients retained protective antibody levels at 6 months. Immunosuppressive drugs and low lymphocyte counts in peripheral blood correlated with lower IgG(S-RBD) titers at 6 months. Four patients (3%) developed PCR-documented SARS-CoV-2 infection and one died.

Splenectomy before allogeneic hematopoietic cell transplantation for myelofibrosis: A French nationwide study.

The value of pretransplant splenectomy in patients with myelofibrosis (MF) is subject to debate, since the procedure may preclude subsequent allogeneic hematopoietic cell transplantation (allo-HCT). To determine the impact of pretransplant splenectomy on the incidence of allo-HCT, we conducted a comprehensive retrospective study of all patients with MF for whom an unrelated donor search had been initiated via the French bone marrow transplantation registry (RFGM) between 1 January 2008 and 1 January 2017. Additional data were collected from the patients' medical files and a database held by the French-Language Society for Bone Marrow Transplantation and Cell Therapy (SFGM-TC). We used a multistate model with four states ("RFGM registration"; "splenectomy"; "death before allo-HCT", and "allo-HCT") to evaluate the association between splenectomy and the incidence of allo-HCT. The study included 530 patients from 57 centers. With a median follow-up time of 6 years, we observed 81 splenectomies, 99 deaths before allo-HCT (90 without splenectomy and nine after), and 333 allo-HCTs (268 without splenectomy and 65 after). In a bivariable analysis, the hazard ratio [95% confidence interval (CI)] for the association of splenectomy with allo-HCT was 7.2 [5.1-10.3] in the first 4 months and 1.18 [0.69-2.03] thereafter. The hazard ratio [95% CI] for death associated with splenectomy was 1.58 [0.79-3.14]. These reassuring results suggest that splenectomy does not preclude allo-HCT in patients with MF.

Transient antibody targeting of CD45RC inhibits the development of graft-versus-host disease.

Allogeneic bone marrow transplantation (BMT) is a widely spread treatment of many hematological diseases, but its most important side effect is graft-versus-host disease (GVHD). Despite the development of new therapies, acute GVHD (aGVHD) occurs in 30% to 50% of allogeneic BMT and is characterized by the generation of effector T (Teff) cells with production of inflammatory cytokines. We previously demonstrated that a short anti-CD45RC monoclonal antibody (mAb) treatment in a heart allograft rat model transiently decreased CD45RChigh Teff cells and increased regulatory T cell (Treg) number and function allowing long-term donor-specific tolerance. Here, we demonstrated in rat and mouse allogeneic GVHD, as well as in xenogeneic GVHD mediated by human T cells in NSG mice, that both ex vivo depletion of CD45RChigh T cells and in vivo treatment with short-course anti-CD45RC mAbs inhibited aGVHD. In the rat model, we demonstrated that long surviving animals treated with anti-CD45RC mAbs were fully engrafted with donor cells and developed a donor-specific tolerance. Finally, we validated the rejection of a human tumor in NSG mice infused with human cells and treated with anti-CD45RC mAbs. The anti-human CD45RC mAbs showed a favorable safety profile because it did not abolish human memory antiviral immune responses, nor trigger cytokine release in in vitro assays. Altogether, our results show the potential of a prophylactic treatment with anti-human CD45RC mAbs in combination with rapamycin as a new therapy to treat aGVHD without abolishing the antitumor effect.

Long-Term Immunity to Measles after Allogeneic Hematopoietic Cell Transplantation: Factors Associated with Seroprotection before Revaccination.

Measles can be a life-threatening infection in immunocompromised patients, especially after allogeneic hematopoietic cell transplantation (HCT) because of the corresponding loss of immunity. However, measles vaccines are live-attenuated, which is why measles vaccinations are recommended only in seronegative HCT recipients and in specific conditions. However, little data exist on the rates of seroprotection to measles with the current conditioning regimens and in long-term follow-up. The objectives of this study were to assess measles immunity before considering vaccination in a cohort of allogeneic HCT long-term survivors and to identify the factors associated with seropositivity/seroprotection. One hundred and twenty-six patients who underwent transplantation between 1 and 39 years earlier (median, 9 years) were assessed for measles immunity. Measles IgG titers were determined with an automated chemiluminescent immunoassay. Seropositivity/seroprotection was defined by an IgG titer >16.5 UA/mL. Patients underwent transplantation with a reduced-intensity conditioning (RIC) or nonmyeloablative (NMA) conditioning in 46% of cases, mainly for acute leukemia (61%). Seventy-eight of the 126 patients (62%) were seropositive/seroprotected for measles. Among the seropositive patients, the patients who had been vaccinated before transplantation had a lower median IgG titer compared with those who had not (48 UA/mL versus 116 UA/mL). Myeloproliferative disorder, RIC or NMA conditioning, and absence of acute grade ≥II graft-versus-host disease were associated with seropositivity/seroprotection. With a 62% rate of seropositivity/seroprotection for measles at a median of 9 years after transplantation, our findings strongly support a systematic assessment of anti-measles antibody titers to avoid unnecessary vaccination in seroprotected patients.

Donor-Derived Myeloid Heme Oxygenase-1 Controls the Development of Graft-Versus-Host Disease.

Graft-versus-host disease (GVHD) remains a major clinical drawback of allogeneic hematopoietic stem cell transplantation (HSCT). Here, we investigated how the stress responsive heme catabolizing enzyme heme oxygenase-1 (HO-1, encoded by HMOX1) regulates GVHD in response to allogeneic hematopoietic stem cell transplantation in mice and humans. We found that deletion of the Hmox1 allele, specifically in the myeloid compartment of mouse donor bone marrow, promotes the development of aggressive GVHD after allogeneic transplantation. The mechanism driving GVHD in mice transplanted with allogeneic bone marrow lacking HO-1 expression in the myeloid compartment involves enhanced T cell alloreactivity. The clinical relevance of these observations was validated in two independent cohorts of HSCT patients. Individuals transplanted with hematopoietic stem cells from donors carrying a long homozygous (GT)n repeat polymorphism (L/L) in the HMOX1 promoter, which is associated with lower HO-1 expression, were at higher risk of developing severe acute GVHD as compared to donors carrying a short (GT)n repeat (S/L or S/S) polymorphism associated with higher HO-1 expression. In this study, we showed the unique importance of donor-derived myeloid HO-1 in the prevention of lethal experimental GVHD and we corroborated this observation by demonstrating the association between human HMOX1 (GT)n microsatellite polymorphisms and the incidence of severe acute GVHD in two independent HSCT patient cohorts. Donor-derived myeloid HO-1 constitutes a potential therapeutic target for HSCT patients and large-scale prospective studies in HSCT patients are necessary to validate the HO-1 L/L genotype as an independent risk factor for developing severe acute GVHD.

Antipneumococcal Seroprotection Years After Vaccination in Allogeneic Hematopoietic Cell Transplant Recipients.

BACKGROUND: International guidelines recommend vaccinating allogeneic hematopoietic cell transplant (HCT) recipients at 3 months after transplant, giving 3 doses of pneumococcal conjugate vaccine (PCV) followed by either a dose of 23-valent pneumococcal polysaccharide vaccine (PSV23) or a fourth PCV dose in the case of graft-versus-host disease (GvHD). However, the long-term immunity after this regimen is unknown, and there is no recommendation from 24 months after transplant regarding boosts. Our objective was to assess the antipneumococcal antibody titers and seroprotection rates of allogeneic HCT recipients years after different schedules of vaccination. METHODS: We assessed 100 adult HCT recipients a median of 9.3 years (range: 1.7-40) after transplant. All patients had received at least one dose of PCV and were assessed for antipneumococcal immunoglobulin G (IgG) antibody titers against the 7 serotypes shared by PCV7, PCV13, and PSV23. Sixty-six percent of the patients had been vaccinated according to the current guidelines. RESULTS: Considering an IgG titer ≥ 0.35 µg/mL as protective for each serotype, the seroprotection rate was 50% for 7/7 serotypes and 70% for 5/7 serotypes, with no differences between the different vaccination schedules. The lack of seroprotection was associated with a transplant performed not in complete remission or from a cord-blood unit, a relapse after transplant, or chronic GvHD at assessment. CONCLUSION: Because only half of the vaccinated patients had long-term protection, pending prospective studies defining the best boost program after the initial one, we recommend the assessment of specific IgG titers starting from 24 months to decide for further doses.

Toxoplasmosis as an Early Complication of Allogeneic Hematopoietic Cell Transplantation.

Among 419 consecutive allogeneic hematopoietic cell transplant recipients, we observed 17 (4.0%) cases of toxoplasmosis at a median time of day 45 (range, 6 to 322) after transplant. Seven of these 17 cases occurred before day 30 after transplant. Because of the lack of PCR screening and trimethoprim-sulfamethoxazole prophylaxis before engraftment, the diagnosis of toxoplasmosis was late, and 5 of these 7 patients died. Analyzing these cases, early Toxoplasma blood PCR screening, starting from transplant, is crucial.

Pneumocystis jirovecii pneumonia prophylaxis in allogeneic hematopoietic cell transplant recipients: can we always follow the guidelines?

Pneumocystis jirovecii pneumonia (PCP) is a life-threatening disease in allogeneic hematopoietic cell transplantation (HCT) recipients. Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred prophylaxis but has significant toxicity. We assessed 139 consecutive HCT patients for PCP prophylaxis in our center. According to our procedures, TMP-SMX should be given as first-line prophylaxis from engraftment. In case of intolerance, atovaquone (ATO) or aerosolized pentamidine may be given. Thirteen (9.3%) patients did not receive prophylaxis because they early died. Of the 126 prophylaxed patients, 113 (90%) received TMP-SMX and 13 (10%) received ATO as first-line regimen. However, only 51/113 (45%) patients received TMP-SMX as the sole prophylaxis: 60 patients were switched to ATO because of side effect. There were 18 PCP cases: 3 occurred before engraftment, 7 occurred under ATO, 3 occurred while prophylaxis was pending the resolution of side effects, and 5 occurred after stopping prophylaxis. No cases occurred under TMP-SMX while 7 (9.6%) cases occurred under first-(n = 13) or second (n = 60)-line ATO. There are many concerns about PCP prophylaxis after HCT: patients may develop PCP before engraftment or several months after stopping immunosuppressors, and half of them do not receive TMP-SMX all along the at-risk periods. New prophylactic drugs and strategies should be evaluated.

De-escalation and discontinuation strategies in high-risk neutropenic patients: an interrupted time series analyses of antimicrobial consumption and impact on outcome.

Febrile neutropenia (FN) is the main reason for antibiotic prescription in hematology wards where, on the other hand, antibiotic stewardship (AS) is poorly explored. The objectives of the present study were to evaluate (1) the impact of an AS intervention on antibiotic consumption and (2) the applicability and acceptance rate of the intervention and its clinical impact. A persuasive AS intervention based on European Conference on Infection in Leukaemia (ECIL) guidelines for FN was implemented in a high-risk hematology ward in a tertiary referral public university hospital. This included the creation and diffusion of flow charts on de-escalation and discontinuation of antibiotics for FN, and the introduction in the team of a doctor dedicated to the implementation of flow charts and to antibiotic prescription revision. All consecutive patients receiving antibiotics during hospitalization were included. A segmented linear regression model was performed for the evaluation of antibiotic consumption, taking into account 1-year pre-intervention period and 6-month intervention period. Overall, 137 consecutive antibiotic prescriptions were re-evaluated, 100 prescriptions were for FN. A significant reduction of the level of carbapenem consumption was observed during the intervention period (level change (estimate coefficient ± standard error) = - 135.28 ± 59.49; p = 0.04). Applicability and acceptability of flow charts were high. No differences in terms of intensive care unit transfers, bacteremia incidence, and mortality were found. A persuasive AS intervention in hematology significantly reduced carbapenem consumption without affecting outcome and was well accepted. This should encourage further applications of ECIL guidelines for FN.

Similar outcome of allogeneic stem cell transplantation after myeloablative and sequential conditioning regimen in patients with refractory or relapsed acute myeloid leukemia: A study from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire.

Patients with acute myeloid leukemia (AML) in relapse or refractory to induction therapy have a dismal prognosis. Allogeneic hematopoietic stem cell transplantation is the only curative option. In these patients, we aimed to compare the results of a myeloablative transplant versus a sequential approach consisting in a cytoreductive chemotherapy followed by a reduced intensity conditioning regimen and prophylactic donor lymphocytes infusions. We retrospectively analyzed 99 patients aged 18-50 years, transplanted for a refractory (52%) or a relapsed AML not in remission (48%). Fifty-eight patients received a sequential approach and 41 patients a myeloablative conditioning regimen. Only 6 patients received prophylactic donor lymphocytes infusions. With a median follow-up of 48 months, 2-year overall survival was 39%, 95% confidence interval (CI) (24-53) in the myeloablative group versus 33%, 95% CI (21-45) in the sequential groups (P = .39), and 2-year cumulative incidence of relapse (CIR) was 57% versus 50% respectively (P = .99). Nonrelapse mortality was not higher in the myeloablative group (17% versus 15%, P = .44). In multivariate analysis, overall survival, CIR and nonrelapse mortality remained similar between the two groups. However, in multivariate analysis, sequential conditioning led to fewer acute grade II-IV graft versus host disease (GVHD) (HR for sequential approach = 0.37; 95% CI: 0.21-0.65; P < .001) without a significant impact on chronic GVHD (all grades and extensive). In young patients with refractory or relapsed AML, myeloablative transplant and sequential approach offer similar outcomes except for a lower incidence of acute GvHD after a sequential transplant.

Economic burden of preemptive treatment of CMV infection after allogeneic stem cell transplantation: a retrospective study of 208 consecutive patients.

BACKGROUND: Cytomegalovirus (CMV) infection and disease (CMV episodes) are global concerns after allogeneic hematopoietic stem cell transplantation (HSCT). They affect survival, both by direct and indirect effects. Due to safety issues of current anti-CMV antivirals, long-term CMV prophylaxis is poorly tolerated and the most common strategy to decrease the incidence of CMV disease is preemptive. New, less toxic, molecules are currently being assessed for CMV prophylaxis which should replace or considerably decrease the preemptive approach. The aim of this study was to assess the economic burden of CMV episodes after HSCT with a preemptive approach. METHODS: We analyzed data from 208 consecutive adults transplanted in our institution, between 2008 and 2013. Hospital resource utilization was retrieved via the linked hospital admissions and Diagnostic Related Groups for the period of conditioning to 12 months after transplant. RESULTS: CMV episodes occurred in 70 patients (34%) over the first 12 months following HSCT, after a mean of 75 days (median: 46 (7-334)). The mean total length of stay was significantly associated with the occurrence of a CMV episode (113.9 vs. 87.5 days, p = 0.0002) but was associated neither with the pre-transplant CMV serology of donors/recipients nor with survival. The mean cost of transplant was €104,016 (SD = €37,281) after 12 months. Bivariate and multivariate analyses indicated that the occurrence of >1 CMV episode increased the costs of allogeneic HSCT by 25-30% (p < 0.0001). CONCLUSION: Our study, which is the largest, single-institution cost study of allogeneic HSCT in Europe, shows that two or more CMV episodes significantly increased the transplant cost. New prophylactic strategies to prevent CMV infection and disease should decrease transplant costs.

[Preventative and therapeutic relapse strategies after allogeneic hematopoietic stem cell transplantation: Guidelines from the Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC)]. / Stratégies préventives et thérapeutiques de la rechute après allogreffe de cellules souches hématopoïétiques : recommandations de la Société francophone de greffe de moelle et de thérapie cellulaire (SFGM-TC).

Disease relapse remains the first cause of mortality of hematological malignancies after allogeneic hematopoietic stem cell transplantation (allo-HCT). The risk of recurrence is elevated in patients with high-risk cytogenetic or molecular abnormalities, as well as when allo-HCT is performed in patients with refractory disease or with persistent molecular or radiological (PET-CT scan) residual disease. Within the frame of the 7th annual workshops of the francophone society for bone marrow transplantation and cellular therapy, the working group reviewed the literature in order to elaborate unified guidelines for the prevention and treatment of relapse after allo-HCT. For high risk AML and MDS, a post transplant maintenance strategy is possible, using hypomethylating agents or TKI anti-FLT3 when the target is present. For Philadelphia positive ALL, there was a consensus for the use of post-transplant TKI maintenance. For lymphomas, there are no strong data on the use of post-transplant maintenance, and hence a preemptive strategy is recommended based on modulation of immunosuppression, close follow-up of donor chimerism, and donor lymphocytes infusion. For multiple myeloma, even though the indication of allo-HCT is controversial, our recommendation is post transplant maintenance using bortezomib, due to its a good toxicity profile without increasing the risk of GVHD.