Phase I study of zoledronic acid combined with escalated doses of interleukine-2 for early in vivo generation of Vγ9Vδ2 T-cells after haploidentical stem cell transplant with posttransplant cyclophosphamide.

The presence of donor Vγ9Vδ2 T-cells after haploidentical hematopoietic stem cell transplant (h-HSCT) has been associated with improved disease-free survival. These cells kill tumor cells in a non-MHC restricted manner, do not induce graft-versus-host disease (GVHD), and can be generated by stimulation with zoledronic acid (ZA) in combination with interleukin-2 (IL-2). This monocentric phase I, open-label, dose-escalating study (ClinicalTrials.gov: NCT03862833) aimed at evaluating the safety and possibility to generate Vγ9Vδ2 T-cells early after h-HSCT. It applied a standard 3 + 3 protocol to determine the maximum tolerated dose (MTD) of increasing low-doses of IL-2 (5 days [d] per week, 4 weeks) in combination with a single dose of ZA, starting both the first Monday after d + 15 posttransplant. Vγ9Vδ2 T-cell monitoring was performed by multiparameter flow cytometry on blood samples and compared with a control cohort of h-HSCT recipients. Twenty-six patients were included between April 2019 and September 2022, 16 of whom being ultimately treated and seven being controls who received h-HSCT only. At the three dose levels tested, 1, 0, and 1 dose-limiting toxicities were observed. MTD was not reached. A significantly higher number of Vγ9Vδ2 T-cells was observed during IL-2 treatment compared with controls. In conclusion, early in vivo generation of Vγ9Vδ2 T-cells is feasible after h-HSCT by using a combination of ZA and repeated IL-2 infusions. This study paves the way to a future phase 2 study, with the hope to document lesser posttransplant relapse with this particular adaptive immunotherapy.

Peripheral levels of monocytic myeloid-derived suppressive cells before and after first induction predict relapse and survivals in AML patients.

Myeloid Derived Suppressive Cells (MDSC) are capable to suppress innate and adaptive immune responses, thus favouring solid cancer progression. However, little is known about the role of MDSC in acute myeloid leukaemia (AML). In this monocentric prospective study, 73 adult AML patients, eligible for first-line intensive chemotherapy, were included with the aim to study the influence on long-term outcomes of peripheral blood (PB) levels of monocytic (M) MDSC (M-MDSC) assessed by flow cytometry. A percentage of peripheral M-MDSC higher than 0.55% of leukocytes at diagnosis and a decrease of M-MDSC% after induction came out both as independent negative prognostic factors for leukaemia-free and overall survival.

Effectiveness of a third dose of BNT162b2 anti-SARS-CoV-2 mRNA vaccine over a 6-month follow-up period in allogenic hematopoietic stem cells recipients.

This study reports the effectiveness of three injections of BNT162b2 anti-SARS-CoV-2 mRNA vaccine in 141 Allo-HSCT recipients with a median follow-up of 6 months post-third shot. We demonstrate a long-term high protection of Allo-HSCT recipients since only 2 infections and one death related to COVID-19 occurred.

Dramatic Recovery after Etoposide Phosphate Infusion for Hemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome following Treatment with Tisagenlecleucel in a Young Patient with Relapsed Acute Lymphoblastic Leukemia: A Case Report.

The occurrence of a secondary hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS) after CAR T-cell infusion is very rare and mostly fatal. Treatment recommendations for such a complication are not yet established. Here, we report the dramatic recovery of HLH/MAS following tisagenlecleucel infusion in a young patient with relapsed acute lymphoblastic leukemia using etoposide phosphate (EP). We propose that monitoring for the occurrence of HLH/MAS should be part of surveillance after CAR T-cell infusion and that EP treatment appears to be useful to control this severe and rare complication.

Pomalidomide, cyclophosphamide, and dexamethasone for relapsed/refractory multiple myeloma patients in a real-life setting: a single-center retrospective study.

Pomalidomide dexamethasone is a standard of care for relapsed multiple myeloma (MM) patients who received at least two prior lines of therapy, including both lenalidomide and proteasome inhibitors (PI). We report here a real-life single-center series of 49 consecutive patients with relapsed and refractory MM treated with the triplet pomalidomide cyclophosphamide dexamethasone (PCD) combination. The median of prior lines of therapy was 3 and all patients were previously exposed to proteasome inhibitors and lenalidomide. The overall response rate was 76%, including 27% very good partial response or better. With a median follow-up of 16 months, the median progression-free survival (PFS) was 7.3 months and the median overall survival was not reached. Regarding safety, most frequent toxicity was hematologic, including 37% grade 3-4 cytopenias. Nine patients (18%) discontinued therapy due to adverse event. Our study confirms that PCD combination is feasible and results in favorable response rate and PFS in comparison with pomalidomide dexamethasone alone.

Single-agent daratumumab in very advanced relapsed and refractory multiple myeloma patients: a real-life single-center retrospective study.

The anti-CD38 monoclonal antibody daratumumab is approved as a single agent for the treatment of patients with relapsed and refractory multiple myeloma (RRMM) who have received at least three prior lines of therapy, including a proteasome inhibitor (PI) and an immunomodulatory agent (IMID), or who are double refractory to a PI and an IMID. To date, no real-life data on the efficacy and tolerance of daratumumab in this setting are available. We report here the results of a single-center series of 41 RRMM patients treated with single-agent daratumumab outside clinical trials. Patients received a median number of 4 prior therapies. All patients were previously exposed to PI and IMID and all patients were refractory to the last line of therapy. Most patients presented with high-risk characteristics, including 24% adverse cytogenetics (del17p/t(4,14)), 31% extramedullary disease and 12% circulating plasmacytosis at time of daratumumab therapy. The overall response rate was 24%, including 5% very good partial response or better. After a median follow-up of 6.5 months, all patients experienced disease relapse. The median progression-free survival was 1.9 months. At the time of disease progression, 44% of patients did not receive subsequent therapy. The median overall survival was 6.5 months. No new safety signal was identified. These real-life results revealed modest efficacy of single-agent daratumumab in advanced patients with RRMM in comparison with data from clinical trials.

Pre-graft vaccination or infection do not decrease COVID-19 infections in recipients of allogeneic stem cell transplantation vaccinated and/or protected by immunotherapy after transplant.

The impact of pre-graft COVID-19 vaccinations in donor or recipient as well as pre-graft infection has been studied in 157 adults having received allogeneic stem cell transplantation (Allo-SCT) for various hematological diseases during the delta/omicron waves. We showed here that pre-Allo-SCT COVID-19 vaccination and/or infection do not provide more protection in patients receiving vaccine, immunotherapy or both after transplant. COVID-19 vaccination is and remains of crucial importance after Allo-SCT, reinforcing the recommendation to start COVID-19 vaccination as soon as the third month following the transplant.

Late Relapse after Allogeneic Stem Cell Transplantation in Patients Treated for Acute Myeloid Leukemia: Relapse Incidence, Characteristics, Role of Conditioning Regimen, and Outcome.

Late relapse, beyond 2 years following alloHSCT for AML, is rare. Among the 376 patients allografted for AML in our center between 1990 and 2016, 142 (38%) relapsed. The majority (68%) of relapses occurred during the first year following transplantation. Beyond 2 years after alloHSCT, relapse was observed in 26 patients, representing 6.9% of the whole transplanted cohort and 18.3% of the relapsing patients. Cytogenetics at relapse was available in 21 patients and remained for 15 of them concordant to that at diagnosis. The majority (85.7%) of the patients were in CR prior to transplant. Thirteen patients had grade 1-2 acute GvHD, while 13 other patients had grade 3-4 acute GvHD. None of these patients subsequently developed chronic GvHD. In multivariate analyses, a predictive factor of the absence of relapse 2 years after transplantation was the development of extensive chronic GVHD. Salvage therapy achieved new CR in 77% of these patients. We conclude that late relapse can affect a significant minority of patients allografted for AML, and the intensity of the conditioning regimen does not seem to have an impact on these relapses. Moreover, we were able to show that those patients can receive effective salvage therapy.

Successful treatment of congenital erythropoietic porphyria using matched unrelated hematopoietic stem cell transplantation in an adult: A case report.

Congenital erythropoietic porphyria (CEP), or Gunther disease, is a rare genetic disease responsible for severe dermatologic, hepatic and/or haematological damages related to the deficient activity of the uroporphyrinogen III synthase. Allogeneic stem cell transplantation (Allo-SCT) represents the only curative treatment and few allotransplanted cases have been reported in children but not in adults. Here we report for the first time the successful cure of a 46-year old man with CEP with a 5-year follow-up after Allo-SCT.

Childhood myelodysplastic syndromes: Is cytoreductive therapy useful before allogeneic hematopoietic stem cell transplantation?

For most patients with childhood myelodysplastic syndrome (cMDS), allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option. In the case of increased blasts (cMDS-IB), the benefit of pretransplant cytoreductive therapy remains controversial. In this multicenter retrospective study, the outcomes of all French children who underwent allo-HSCT for cMDS reported in the SFGM-TC registry between 2000 and 2020 were analyzed (n = 84). The median age at transplantation was 10.2 years. HSCT was performed from matched sibling donors (MSD) in 29% of the cases, matched unrelated donors (MUD) in 44%, haploidentical in 6%, and cord blood in 21%. Myeloablative conditioning was used in 91% of cases. Forty-eight percent of patients presented with cMDS-IB at diagnosis (median BM blasts: 8%). Among them, 50% received pretransplant cytoreductive therapy. Five-year overall survival (OS), cumulative incidence of nonrelapse mortality (NRM), and relapse were 67%, 26%, and 12%, respectively. Six-month cumulative incidence of grade II-IV acute graft-versus-host disease was 46%. Considering the whole cohort, age under 12, busulfan/cyclophosphamide/melphalan conditioning or MUD were associated with poorer 5-year OS. In the cMDS-IB subgroup, pretransplant cytoreductive therapy was associated with a better OS in univariate analysis. This seems to be mainly due to a decreased NRM since no impact on the incidence of relapse was observed. Overall, those data may argue in favor of cytoreduction for cMDS-IB. They need to be confirmed on a larger scale and prospectively.

Post-transplant cyclophosphamide as sole GHVD prophylaxis after matched reduced-intensity conditioning allotransplant.

BACKGROUND: Post-transplant cyclophosphamide (PTCY) alone as graft-versus-host disease (GVHD) prophylaxis may avoid/reduce short- and mid-term toxicities of drugs commonly used for GVHD prophylaxis, accelerate immune reconstitution after the graft to decrease infections and facilitate the early integration of adjunct maintenance therapies to prevent relapse. OBJECTIVE: A prospective phase 2 study was designed in order to assess the feasibility and safety of PTCY as a sole GVHD prophylaxis in adult patients receiving a Baltimore-based reduced-intensity conditioning (RIC) peripheral blood (PB) allogeneic hematopoietic stem cell transplantation (Allo-HSCT) with a matched donor. STUDY DESIGN: Patients were planned to be included stepwise up to 59 evaluable PTCY recipients, in order to be able to stop the protocol in case of excessive corticosteroid resistant grade 3-4 severe acute GVHD (aGVHD). Because a high incidence of grade 2-4 aGVHD was observed after analysis of the first 27 patients, the protocol was amended to test the addition of 1 day of anti-thymoglobulin to PTCY. In spite of this, the trial had to be stopped after 38 treated patients, because of an unacceptable rate of grade 3-4 aGVHD. Donors were matched related to 12 patients and unrelated to 26. RESULTS: With a median follow-up of 29.6 months, 2-year overall, disease-free and GVHD-free relapse-free (GRFS) survivals were respectively 65.4%, 62.1% and 46.9%. Cumulative incidences of grade 2-4 and 3-4 aGVHD at day 100 were 52.6% and 21.1%, respectively, while that of moderate/severe chronic(c) GVHD was 15.7% at 2 years. Addition of ATG to PTCY did influence neither aGVHD, cGVHD nor GRFS. CONCLUSION: Despite paradoxically good survivals, especially GRFS, this study failed to demonstrate that PTCY (± ATG) alone can be used for Baltimore-based RIC PB Allo-HSCT with matched donors. Other combinations should be tested to try and avoid long-term use of immunosuppressive drugs following Allo-HSCT in this setting.

Assessment of monocytic-myeloid-derived suppressive cells (M-MDSC) before and after allogeneic hematopoietic stem cell transplantation in acute leukemia patients.

In this monocentric prospective study, the influence on long-term outcomes of peripheral blood levels of monocytic-myeloid-derived suppressive cells (M-MDSC) was investigated in 56 patients with acute leukemia (myeloid n = 47; lymphoid n = 9) before and after (Days+60/+90) allogeneic hematopoietic stem cell transplantation (Allo-HSCT). A risk of relapse was found to be associated with a level of pregraft M-MDSC above 1.4% by ROC curve analysis. In multivariate analysis, this threshold retained a strong statistical significance (HR: 5.94 [2.09-16.87], p = 0.001). Considering only the group of patients who were in complete remission prior to Allo-HSCT (n = 44), a significant prediction of relapse was found to be associated, in multivariate analysis, with a level of pregraft M-MDSC above 1.4% (HR: 55.01 [14.95-202.37], p < 0.001) together with pregraft-positive measurable -residual disease (MRD) (HR: 11.04 [1.89-64.67], p = 0.008). A poorer OS (HR: 6.05 [1.24-29.59], p = 0.026) and disease-free survival (HR: 6.52 [1.41-30.19], p = 0.016) were also associated with higher levels of pregraft M-MDSC. Remarkably, no relapse occurred in patients with pregraft-negative MRD and ≤1.4% of M-MDSC (vs. a 3-year relapse rate of 60% for others, p = 0.004). Patients developing grade 3-4 acute graft-versus-host-disease (GVHD, median occurrence: day+30 posttransplant) showed significantly higher levels of M-MDSC% at days +60 and +90, suggesting a possible amplification of these immunosuppressive cells as a reaction to GVHD. In conclusion, this prospective study demonstrates a negative impact of higher proportions of peripheral M-MDSC before Allo-HSCT in leukemic patients. This paves the way to potential therapeutic intervention to decrease M-MDSC levels before Allo-HSCT and thus perhaps the incidence of relapse in such patients.

Non-Expressed Donor KIR3DL1 Alleles May Represent a Risk Factor for Relapse after T-Replete Haploidentical Hematopoietic Stem Cell Transplantation.

KIR3DL1 alleles are expressed at different levels on the natural killer (NK) cell surface. In particular, the non-expressed KIR3DL1*004 allele appears to be common in Caucasian populations. However, the overall distribution of non-expressed KIR3DL1 alleles and their clinical relevance after T-replete haploidentical hematopoietic stem cell transplantation (hHSCT) with post-transplant cyclophosphamide remain poorly documented in European populations. In a cohort of French blood donors (N = 278), we compared the distribution of expressed and non-expressed KIR3DL1 alleles using next-generation sequencing (NGS) technology combined with multi-color flow cytometry. We confirmed the predominance of the non-expressed KIR3DL1*004 allele. Using allele-specific constructs, the phenotype and function of the uncommon KIR3DL1*019 allotype were characterized using the Jurkat T cell line and NKL transfectants. Although poorly expressed on the NK cell surface, KIR3DL1*019 is retained within NK cells, where it induces missing self-recognition of the Bw4 epitope. Transposing our in vitro observations to a cohort of hHSCT patients (N = 186) led us to observe that non-expressed KIR3DL1 HSC grafts increased the incidence of relapse in patients with myeloid diseases. Non-expressed KIR3DL1 alleles could, therefore, influence the outcome of hHSCT.

Tocilizumab in combination with a standard induction chemotherapy in acute myeloid leukaemia patients (TOCILAM study): a single-centre, single-arm, phase 1 trial.

Background: In acute myeloid leukaemia (AML), interleukin-6 (IL-6) promotes chemo-resistance and its levels correlate with poor prognosis. IL-6 blockade may represent a promising therapeutic strategy. We aimed to test, tocilizumab, an anti-IL-6 receptor (R) monoclonal antibody in combination with standard intensive AML induction chemotherapy. Methods: This investigator-initiated single-centre phase 1 trial was conducted at Nantes University Hospital in France. According to a continual reassessment method, three escalating doses were tested of intravenous (IV) tocilizumab (4, 6, and 8 mg/kg) administered at day (d) 8 of a standard AML induction chemotherapy (IV idarubicine 8 mg/m2 d1 to d5 + IV cytarabine 100 mg/m2 d1 to d7). All adults (aged ≥ 18 years) with an Eastern Cooperative Oncology Group performance status of 0-2 and with a newly diagnosed (excluding patients with a favourable risk according to ELN-2017 classification if <60 year-old) or a relapsed/refractory AML were eligible. The primary objective was to determine the maximum tolerated dose of tocilizumab to administrate with a standard intensive AML induction. Safety outcomes were continuously monitored for at each participant contact. This trial is registered with ClinicalTrials.gov, NCT04547062. Findings: Between Dec 29, 2020 and Dec 1, 2022, 12 patients were enrolled, of whom 75% had an ELN-2017 high-risk profile, and were treated with tocilizumab- two patients at 4 mg/kg, two at 6 mg/kg and eight at 8 mg/kg of tocilizumab. No dose-limiting toxicity related to tocilizumab was documented. There were nine serious adverse events, none of which were related to tocilizumab, and there was no treatment-related deaths. MTD was thus not reached. Two deaths occurred during induction. In the remaining ten evaluable patients, nine responded to treatment. Interpretation: The combination of tocilizumab with standard AML intensive induction appears to be safe and resulting responses are encouraging. A dose of 8 mg/kg of tocilizumab given at day 8 of induction could be used for further phase 2/3 studies. Funding: The Leucémie Espoir Atlantique Famille (LEAF)-"Tous avec Fabien" association.

Anti-SARS-CoV-2 vaccines in recipient and/or donor before allotransplant.

The impact of pre-transplant anti-severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccine in 20 recipients of allogeneic hematopoietic stem cell transplantation (Allo-HSCT) and/or their donors is reported here, showing that the persistence of anti-SARS-CoV-2 antibodies can be detected in almost all patients, whatever the type of vaccine used, and up to 9 months post transplant. Also, an anti-SARS-CoV-2 spike glycoprotein CD3+ T-cell response could be detected in six (35%) of 17 evaluable patients. This study provides a rationale to consider anti-SARS-CoV-2 vaccination of both recipients and donors before Allo-HSCT.

SARS-CoV-2 T-Cell Responses in Allogeneic Hematopoietic Stem Cell Recipients following Two Doses of BNT162b2 mRNA Vaccine.

BACKGROUND: At variance to humoral responses, cellular immunity after anti-SARS-CoV-2 vaccines has been poorly explored in recipients of allogeneic hematopoietic stem-cell transplantation (Allo-HSCT), especially within the first post-transplant years where immunosuppression is more profound and harmful. METHODS: SARS-CoV-2 Spike protein-specific T-cell responses were explored after two doses of BNT162b2 mRNA vaccine in 45 Allo-HSCT recipients with a median time from transplant of less than 2 years by using INF-γ ELISPOT assay and flow-cytometry enumeration of CD4+ and CD8+ T lymphocytes with intracellular cytokine production of IFN-γ and TNF-α. RESULTS: A strong TNF-α+ response from SARS-CoV-2-specific CD4+ T-cells was detected in a majority of humoral responders (89%) as well as in a consistent population of non-humoral responders (40%). CONCLUSIONS: T-cells are likely to participate in protection against COVID-19 viral infection, even in the absence of detectable antibody response, especially in the first years post-transplant in Allo-HSCT recipients.

Strong SARS-CoV-2 T-Cell Responses after One or Two COVID-19 Vaccine Boosters in Allogeneic Hematopoietic Stem Cell Recipients.

A full exploration of immune responses is deserved after anti-SARS-CoV-2 vaccination and boosters, especially in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although several reports indicate successful humoral responses in such patients, the literature is scarce on cellular specific immunity. Here, both B- (antibodies) and T-cell responses were explored after one (V3 n = 40) or two (V4 n = 12) BNT162b2 mRNA vaccine boosters in 52 allo-HSCT recipients at a median of 755 days post-transplant (<1 year n = 9). Results were compared with those of 12 controls who had received only one booster (BNT162b2 n = 6; mRNA-1273 n = 6). All controls developed protective antibody levels (>250 BAU/mL) and anti-spike T-cell responses. Similarly, 81% of the patients developed protective antibody levels, without difference between V3 and V4 (82.5% vs. 75%, p = 0.63), and 85% displayed T-cell responses. The median frequency of anti-spike T cells did not differ either between controls or the whole cohort of patients, although it was significantly lower for V3 (but not V4) patients. COVID-19 infections were solely observed in individuals having received only one booster. These results indicate that four vaccine injections help to achieve a satisfactory level of both humoral and cellular immune protection in allo-HSCT patients.