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•PNH is a rare blood disease that can affect children, with symptoms that may result in fatal complications if left untreated.•In children with PNH ravulizumab controlled terminal complement and relieved symptoms with mostly mild treatment-related side effects.

•The combination of vemurafenib and intermediate-dose Ara-C and 2-CdA is feasible and effective for unmaintained remission in pediatric LCH

Acquired thrombotic thrombocytopenic (aTTP) purpura is a life-threatening condition that can lead to devastating thromboembolic events. Recently, caplacizumab has been shown to rapidly restore platelet numbers and reduce the risk of severe end-organ damage when added to plasma exchanges (PEXs) and immunosuppression (IST). Here, we report the outcomes in 3 children with aTTP who were treated with caplacizumab in combination with PEXs and IST. In all 3 patients, platelet count increased to >15,000/mm3in 24 h and normalized on day 4, whereas normalization of ADAMTS13 activity >50% and elimination of the inhibitor was achieved after 18 to 89 days. Epistaxis was observed in 2 patients and was the only side effect related to caplacizumab. Caplacizumab is a promising agent for first-line treatment of children with aTTP.

We compared the efficacy and safety of eltrombopag (ELTR) combined with immunosuppressive therapy (IST) and IST alone in treatment-naïve children with severe (SAA) and very severe (vSAA) aplastic anemia. Ninety-eight pediatric patients were randomized to receive horse antithymocyte globulin (hATG) and cyclosporin A (CsA) with (n = 49) or without (n = 49) ELTR. The primary endpoint was the overall response rate (ORR) at 4 months. After 4 months, nonresponders were crossed over to the alternative group. In all patients, the ORR in ELTR + IST and IST groups was similar (65% vs 53%; P = .218); however, the complete response (CR) rate was significantly higher in the ELTR + IST group (31% vs 12%; P = .027). In severity subgroups, the ORR was 89% vs 57% (P = .028) in favor of IST + ELTR in SAA, but it did not differ in patients with vSAA (52% vs 50%; P = .902). At 6 months after the crossover, 61% of initial ELTR(−) patients achieved a response compared with 17% of initial ELTR(+) patients (P = .016). No significant difference in ELTR + IST and IST groups was observed in the 3-year overall survival (OS) (89% vs 91%; P = .673) or the 3-year event-free survival (EFS) (53% vs 41%; P = .326). There was no unexpected toxicity related to ELTR. Adding ELTR to standard IST was well tolerated and increased the CR rate. The greatest benefit from ELTR combined with IST was observed in patients with SAA but not in those with vSAA. The second course of IST resulted in a high ORR in initial ELTR(−) patients who added ELTR and had limited efficacy among patients who received ELTR upfront. This trial was registered at Clinicaltrials.gov as #NCT03413306.

Romiplostim is a thrombopoietin (TPO) receptor agonist approved for children and adults with immune thrombocytopenia (ITP) for ≥6 months, recommended as second-line treatment. This phase 3b, single-arm, multicenter study investigated long-term efficacy and safety of romiplostim in children ≥1 to <18 years old with ≥6 months’ ITP duration and platelet counts ≤30 × 109/L. Children received weekly subcutaneous romiplostim (1 μg/kg titrated to 10 μg/kg) to maintain platelets within 50 to 200 × 109/L. A subset underwent bone marrow examinations. The primary end point was percentage of time with platelet response during the first 6 months’ treatment (counts ≥50 × 109/L without rescue medication within the preceding 4 weeks). Overall, 203 patients (median age, 10.0 years) received ≥1 dose of romiplostim, median treatment duration was ∼3 years, and median average weekly dose was 6.9 μg/kg. Ninety-five (46.8%) discontinued (lack of efficacy, n = 43 [21.2%]). Platelet responses were achieved a median (interquartile range) of 50.0% (16.7%-83.3%) of the time during the first 6 months, increasing to 78.2% (26.7%-90.4%) during the overall 36-month treatment period. Eleven patients (5.4%) achieved sustained responses (consecutive counts ≥50 × 109/L without ITP medications for ≥24 weeks). Treatment-related adverse events (AEs) occurred in 56 patients (27.6%), with 8 (3.9%) experiencing serious treatment-related AEs; all of these led to discontinuation, including 4 cases of neutralizing antibodies (romiplostim, n = 3; TPO, n = 1). Bleeding occurred in 141 patients (69.5%), decreasing over time; grade ≥3 bleeding events occurred in 20 (9.9%). At year 2, eight of 63 evaluable patients (12.7%) had grade 2 reticulin. Long-term romiplostim resulted in sustained on-treatment platelet responses with an overall safety profile consistent with previous studies. This trial was registered at www.clinicaltrials.gov as #NCT02279173.

•Long-term romiplostim treatment is effective in children with primary ITP; serial bone marrow biopsy results showed no new safety concerns.•Romiplostim injections resulted in 8 AEs of neutralizing antibodies (romiplostim, n = 7 [transient n = 4]; TPO, n = 1 [transient n = 1]).

We recently demonstrated that TCRαβ+/CD19+ graft depletion successfully prevents severe acute and chronic graft-versus-host disease (GVHD) in pediatric patients with primary immunodeficiencies (PID) receiving transplants from both matched unrelated and mismatched related donors. However, in all patients, short-term post-hematopoietic stem cell transplantation (HSCT) immunosuppressive therapy (IST) was used. There are limited data on TCRαβ+/CD19+ graft depletion with no post-HSCT IST implementation. In the current study 74 PID patients who underwent first HSCT from matched unrelated (n=51) or mismatched related donors (n=23) with TCRαβ+/CD19+ graft depletion were included. All received as a conditioning regimen a combination of treosulfan with fludarabine and either melphalan or thiotepa. In all, thymoglobulin 5 mg/kg (days −5, −4, −3) and rituximab at day −1 were used. In 48 patients, various approaches to short-term post-transplantation IST were used, and 26 patients received no post-HSCT IST. The rates of engraftment, acute and chronic GVHD, survival, and mortality were similar in those who received and did not receive IST, with a slightly higher incidence of graft rejection in patients not receiving IST: 19% in the non-IST group against 13% in the IST group (P = .41). The incidence of cytomegalovirus reactivation was 50% and 39% (P = .50) and Epstein-Barr virus reactivation 10% and 0 (P = .20) in the IST and non-IST groups, respectively. No grade 4 adverse events were seen in both groups, although in 19 of 40 (47.5%) patients receiving calcineurin inhibitors, the therapy was discontinued before day 45. More robust immune recovery with both T- and B-lymphocytes was observed in the non-IST group. To conclude, TCRαβ+/CD19+ in combination with particular serotherapy effectively prevents severe acute and chronic GVHD in PID. Regarding remaining risks of infectious complications and additional drug-related toxicity, there are no benefits to post-HSCT IST use in these patients.

Graft failure (GF) remains a serious issue of hematopoietic stem cell transplantation (HSCT) in inborn errors of immunity (IEI). Second HSCT is the only salvage therapy for GF. There are no uniform strategies for the second HSCTs and limited data are available on the second HSCT outcomes. 48 patients with various IEI received second allogeneic HSCT from 2013 to 2020. Different conditioning regimens were used, divided into two main groups: containing myeloablative doses of busulfan/treosulfan (n= 19) and lymphoid irradiation 2–6 Gy (n= 22). Irradiation-containing conditioning was predominantly used in suspected immune-mediated rejection of the first graft. Matched unrelated donor was used in 28 patients, mismatched related in 18, and matched related in 1. 35 patients received TCRαβ/CD19 graft depletion. The median follow-up time was 2.4 years post-HSCT. One patient died at conditioning. The OS was 0.63 (95% CI: 0.41–0.85) after busulfan/treosulfan and 0.68 (95% CI: 0.48–0.88) after irradiation-based conditioning, p= 0.66. Active infection at HSCT significantly influenced OS: 0.43 (95% CI: 0.17–0.69) versus 0.73 (95% CI: 0.58–0.88) without infection, p= 0.004. The cumulative incidence of GF was 0.15 (95% CI: 0.08–0.29). To conclude, an individualized approach is required for the second HSCT in IEI. Low-dose lymphoid irradiation in suspected immune-mediated GF may be a feasible option.

The presence of minimal/measurable residual disease (MRD) before or after hematopoietic stem cell transplantation (HSCT) is known as a predictor of poor outcome in patients with acute myeloid (AML) or lymphoblastic (ALL) leukemia. When performed with multiparameter flow cytometry (MFC), assessment of residual leukemic cells after HSCT may be limited by therapy‐induced shifts in the immunophenotype (e.g., loss of surface molecules used for therapeutic targeting). However, in such cases, questionable cells can be isolated and tested for hematopoietic chimerism to clarify their origin. Questionable cell populations were detected during the MFC‐based MRD monitoring of 52 follow‐up bone marrow samples from 37 patients diagnosed with T cell neoplasms (n=14), B cell precursor ALL (n= 16), AML (n= 7). These cells (suspected leukemic or normal) were isolated by flow cell sorting and tested for hematopoietic chimerism by RTQ‐PCR. The origin of cells was successfully identified in 96.15% of cases (n= 50), which helped to validate the results of MFC‐based MRD monitoring. We believe that a combination of MFC, cell sorting, and chimerism testing may help confirm or disprove MRD presence in complicated cases after HSCT.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the gold standard curative therapy for infants and children with many inborn errors of immunity (IEI), but adolescents and adults with IEI are rarely referred for transplant. Lack of published HSCT outcome data outside small, single-center studies and perceived high risk of transplant-related mortality have delayed the adoption of HSCT for IEI patients presenting or developing significant organ damage later in life. This large retrospective, multicenter HSCT outcome study reports on 329 IEI patients (age range, 15-62.5 years at HSCT). Patients underwent first HSCT between 2000 and 2019. Primary endpoints were overall survival (OS) and event-free survival (EFS). We also evaluated the influence of IEI-subgroup and IEI-specific risk factors at HSCT, including infections, bronchiectasis, colitis, malignancy, inflammatory lung disease, splenectomy, hepatic dysfunction, and systemic immunosuppression. At a median follow-up of 44.3 months, the estimated OS at 1 and 5 years post-HSCT for all patients was 78% and 71%, and EFS was 65% and 62%, respectively, with low rates of severe acute (8%) or extensive chronic (7%) graft-versus-host disease. On univariate analysis, OS and EFS were inferior in patients with primary antibody deficiency, bronchiectasis, prior splenectomy, hepatic comorbidity, and higher hematopoietic cell transplant comorbidity index scores. On multivariable analysis, EFS was inferior in those with a higher number of IEI-associated complications. Neither age nor donor had a significant effect on OS or EFS. We have identified age-independent risk factors for adverse outcome, providing much needed evidence to identify which patients are most likely to benefit from HSCT.

The potential loss of CD19 during targeted treatment of B cell precursor acute lymphoblastic leukemia (BCP‐ALL) can hamper flow cytometric minimal residual disease (MRD) monitoring. In the current study, we present expression data for antigens that are candidates for CD19 substitution: surface CD22, CD24, CD10, and intracellular (i) CD79a. Bone marrow samples from 519 consecutive children (below 18 y.o.) with primary BCP‐ALL were studied with a focus on expression of CD19, CD10, CD22, CD24, and iCD79a. As these antigens are planned to be used as substitutions for CD19 for primary B cell gating, only total expression on the leukemic population (≥95% cells) was considered appropriate. It was found that each of these antigens is totally expressed in nearly 90% of patients. For each single marker, a subgroup of patients without complete positivity presented with BCP‐ALL harboring diverse cytogenetic and molecular genetic aberrations. Based on expression data, we have developed algorithm of simultaneous application of these antigens for initial B‐lineage compartment gating, that is applicable for nearly all patients after CD19 targeting. We conclude that the addition of CD22, CD24, and iCD79a to the conventional antibody panel and their application together with CD10 allow for the identification of B‐lineage compartment including residual tumor blasts, for MFC‐MRD searching in virtually all patients with BCP‐ALL after CD19‐directed treatment.

Relapse of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) may occur in the central nervous system (CNS). Most clinical trials of CAR T-cell therapy excluded patients with active CNS leukemia, partially for concerns of neurotoxicity. Here, we report an international study of fifty-five children and adolescents who received CAR T-cell therapy for relapsed BCP-ALL with CNS involvement at the time of referral. All patients received bridging therapy, 16 still having active CNS disease at the time of lymphodepletion. Twelve patients received CD28-based CAR T-cells, 9 being subsequently treated with allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Forty-three patients received 4-1BB-based CAR T-cells. Cytokine-release syndrome (CRS) and neurotoxicity occurred in 65% and 38% of patients, respectively, more frequently following treatment with CD28-based CARs. Fifty-one of 54 evaluable patients (94%) achieved complete response following this therapy. Relapse occurred in 22 patients: 19/43 following 4-1BB-based CARs (12 CNS relapses), and 3/12 after CD28-based CARs with subsequent HSCT (no CNS relapse). Patients treated with tisagenlecleucel for an isolated CNS relapse had a high incidence of a subsequent CNS relapse (6 of 8). CAR T-cells were found to be effective in this cohort, though the risk of CNS relapse was not completely mitigated by this approach.

The delayed recovery of adaptive immunity underlies transplant-related mortality (TRM) after αβ T cell-depleted hematopoietic stem cell transplantation (HSCT). We tested the use of low-dose memory donor lymphocyte infusions (mDLIs) after engraftment of αβ T cell-depleted grafts.

Depletion of αβ T cells from the graft prevents graft-vs.-host disease (GVHD) and improves outcome of HSCT from haploidentical donors. In a randomized trial, we aimed to evaluate the safety and efficacy of low-dose memory (CD45RA-depleted) donor lymphocytes (mDLI) after HSCT with αβ T-cell depletion. A cohort of 149 children was enrolled, 76 were randomized to receive scheduled mDLI and 73 received standard care. Conditioning was based on either 12 Gy total body irradiation or treosulfan. Rabbit antithymocyte globulin was replaced by tocilizumab and abatacept. Primary end points were the incidence of acute GVHD grades II–IV and the incidence of cytomegalovirus (CMV) viremia. The incidence of grades II–IV aGVHD was 14% in the experimental arm and 12% in the control arm, p—0.8. The incidence of CMV viremia was 45% in the experimental arm and 55% in the control arm, p—0.4. Overall, in the total cohort 2-year NRM was 2%, cumulative incidence of relapse was 25%, event-free survival 71%, and overall survival 80%, without difference between the study arms. Memory DLI was associated with improved recovery of CMV-specific T-cell responses in a subcohort of CMV IgG seropositive recipients.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine ± thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan- vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged <5 years at HSCT had a significantly better overall survival. The overall cumulative incidences of grade III to IV acute GVHD and extensive/moderate/severe chronic GVHD were 6.6% and 2.1%, respectively. Patients receiving treosulfan-based conditioning had a higher incidence of graft failure and mixed donor chimerism and more frequently underwent secondary procedures (second HSCT, unconditioned stem cell boost, donor lymphocyte infusion, or splenectomy). In summary, HSCT for WAS with conditioning regimens currently recommended by IEWP results in excellent survival and low rates of GVHD, regardless of donor or stem cell source, but age ≥5 years remains a risk factor for overall survival.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine ± thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan- vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged <5 years at HSCT had a significantly better overall survival. The overall cumulative incidences of grade III to IV acute GVHD and extensive/moderate/severe chronic GVHD were 6.6% and 2.1%, respectively. Patients receiving treosulfan-based conditioning had a higher incidence of graft failure and mixed donor chimerism and more frequently underwent secondary procedures (second HSCT, unconditioned stem cell boost, donor lymphocyte infusion, or splenectomy). In summary, HSCT for WAS with conditioning regimens currently recommended by IEWP results in excellent survival and low rates of GVHD, regardless of donor or stem cell source, but age ≥5 years remains a risk factor for overall survival.

TCRaß+/CD19+ graft depletion effectively prevents graft-versus-host disease (GVHD). In the current study, we compared the outcomes of hematopoietic stem cell transplantation (HSCT) with TCRaß+/CD19+ depletion from matched unrelated donors (MUDs) and mismatched related donors (MMRDs) in patients with primary immunodeficiency (PID). A total of 98 pediatric patients with various PIDs underwent HSCT with TCRaß+/CD19+ graft depletion from MUDs (n = 75) and MMRDs (n = 23). All patients received a fludarabine-/treosulfan-based conditioning regimen, with 73 also receiving a second alkylating agent. For GVHD prophylaxis, all but 2 received serotherapy (antithymocyte globulin) before HSCT and a short course of posttransplant immunosuppression. Neutrophil and platelet engraftment in both the MUD and MMRD groups occurred on days 14 and 13, respectively. The incidence of secondary graft failure was 0.16 and 0.17 (P = .85), respectively. The cumulative incidence of acute GVHD grade 2 to 4 was 0.17 in the MUD group and 0.22 in the MMRD group (P = .7). The incidence of cytomegalovirus (CMV) viremia was 0.5 in the MUD group and 0.6 in the MMRD group (P = .35). The frequency of CMV disease was high (17%), and the most common manifestation was retinitis. The kinetics of immune recovery was similar in both groups. The overall survival was 0.86 in the MUD group and 0.87 in the MMRD group (P = .95). In our experience, there was no difference in the outcomes of HSCT performed from MUD and MMRD. Hence, given the immediate availability of donors, in the absence of HLA-identical siblings, HSCT with TCRaß+/CD19+ graft depletion from MMRDs can be considered as the first choice in patients with PID.

TCRαβ+/CD19+graft depletion effectively prevents graft-versus-host disease (GVHD). In the current study, we compared the outcomes of hematopoietic stem cell transplantation (HSCT) with TCRαβ+/CD19+depletion from matched unrelated donors (MUDs) and mismatched related donors (MMRDs) in patients with primary immunodeficiency (PID). A total of 98 pediatric patients with various PIDs underwent HSCT with TCRαβ+/CD19+graft depletion from MUDs (n = 75) and MMRDs (n = 23). All patients received a fludarabine-/treosulfan-based conditioning regimen, with 73 also receiving a second alkylating agent. For GVHD prophylaxis, all but 2 received serotherapy (antithymocyte globulin) before HSCT and a short course of posttransplant immunosuppression. Neutrophil and platelet engraftment in both the MUD and MMRD groups occurred on days 14 and 13, respectively. The incidence of secondary graft failure was 0.16 and 0.17 (P= .85), respectively. The cumulative incidence of acute GVHD grade 2 to 4 was 0.17 in the MUD group and 0.22 in the MMRD group (P= .7). The incidence of cytomegalovirus (CMV) viremia was 0.5 in the MUD group and 0.6 in the MMRD group (P= .35). The frequency of CMV disease was high (17%), and the most common manifestation was retinitis. The kinetics of immune recovery was similar in both groups. The overall survival was 0.86 in the MUD group and 0.87 in the MMRD group (P= .95). In our experience, there was no difference in the outcomes of HSCT performed from MUD and MMRD. Hence, given the immediate availability of donors, in the absence of HLA-identical siblings, HSCT with TCRαβ+/CD19+graft depletion from MMRDs can be considered as the first choice in patients with PID.

•In case of relapsed/refractory mature T-cell lymphoma in children, allogeneic haploidentical HSCT is a potentially curative method with event-free survival of 67% and overall survival of 78%.•αβ T-cell-depleted haploidentical HSCT is effective, associated with low incidence of GVHD and NRM and provides significant chances of cure even among patients with residual tumor.•Achieving remission before HSCT significantly improves the main outcomes of transplantation.

•The impact of NK-related factors is not straightforward, and multiple factors should be considered.•There was a trend toward a lower risk of relapse associated with high NK cell dose for a KIR-mismatched cohort.•Patients with AML had a significantly higher risk of relapse, associated with high NK graft content on the background of no predicted KIR mismatch.•ATG use was associated with a trend toward reduced risk of relapse for the AML cohort.

Introduction

The phase 2, open-label study (DIALOG) of nilotinib in pediatric patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) met its coprimary end points, showing sustained nilotinib efficacy in patients with newly diagnosed (ND) or imatinib/dasatinib resistant/intolerant (R/I) CML. This update assessed growth and safety profiles in patients who had completed ≥48, 28-day treatment cycles of nilotinib 230 mg/m2 twice daily, or previously discontinued the study. Height was assessed regularly and reported using standard deviation scores (SDSs) based on World Health Organization growth charts. All data were summarized descriptively (cutoff, 6 March 2019). Overall, 33 patients in the R/I cohort and 25 patients in the ND cohort received nilotinib. Each cohort showed a negative slope in height SDS over the course of the study, indicating attenuated growth rates during nilotinib treatment: overall median change from baseline in height SDS after 48 cycles was −0.54 SDS (range, − 1.6 to 0.4) and −0.91 SDS (−1.4 to −0.1) in R/I and ND cohorts, respectively. Patients in the R/I cohort were shorter at baseline than those in the ND cohort, and remained so throughout the study. The most common all-cause adverse events were increased blood bilirubin (53.4%), headache (46.6%), pyrexia (37.9%), and increased alanine transferase (36.2%). Apart from the impact on growth, the safety profile of nilotinib was generally consistent with previous reports. This study was registered on www.clinicaltrials.gov at #NCT01844765.

The phase 2, open-label study (DIALOG) of nilotinib in pediatric patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) met its coprimary end points, showing sustained nilotinib efficacy in patients with newly diagnosed (ND) or imatinib/dasatinib resistant/intolerant (R/I) CML. This update assessed growth and safety profiles in patients who had completed ≥48, 28-day treatment cycles of nilotinib 230 mg/m2twice daily, or previously discontinued the study. Height was assessed regularly and reported using standard deviation scores (SDSs) based on World Health Organization growth charts. All data were summarized descriptively (cutoff, 6 March 2019). Overall, 33 patients in the R/I cohort and 25 patients in the ND cohort received nilotinib. Each cohort showed a negative slope in height SDS over the course of the study, indicating attenuated growth rates during nilotinib treatment: overall median change from baseline in height SDS after 48 cycles was −0.54 SDS (range, − 1.6 to 0.4) and −0.91 SDS (−1.4 to −0.1) in R/I and ND cohorts, respectively. Patients in the R/I cohort were shorter at baseline than those in the ND cohort, and remained so throughout the study. The most common all-cause adverse events were increased blood bilirubin (53.4%), headache (46.6%), pyrexia (37.9%), and increased alanine transferase (36.2%). Apart from the impact on growth, the safety profile of nilotinib was generally consistent with previous reports. This study was registered on www.clinicaltrials.govat #NCT01844765.

Therapy with irreversible Bruton's tyrosine kinase inhibitor ibrutinib in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) is associated with bleeding.

Chronic myeloid leukemia (CML) is rare in children and accounts for =15% of all myeloid leukemia cases. When we initiated this study with nilotinib, imatinib was the only tyrosine kinase inhibitor indicated for pediatric patients with Philadelphia chromosome–positive (Ph+) CML in chronic phase (CP); alternative treatment options were needed, particularly for patients who developed resistance or intolerance (R/I) to imatinib. This phase 2 study enrolled pediatric patients with either Ph+ CML-CP R/I to imatinib or dasatinib or newly diagnosed Ph+ CML-CP. Data presented are from analyses with minimum follow-up of up to 24 cycles (1 cycle is 28 days). Fifty-nine patients with Ph+ CML-CP were enrolled, and 58 were treated (R/I, n = 33; newly diagnosed, n = 25). Major molecular response (MMR) rate at cycle 6 in the R/I cohort was 39.4% (primary end point); 57.6% of patients achieved or maintained MMR and 81.8% achieved or maintained complete cytogenetic response (CCyR) by 24 cycles. In patients with newly diagnosed disease, rates of MMR by cycle 12 and CCyR at cycle 12 were 64.0% each (primary end points); by cycle 24, cumulative MMR and CCyR rates were 68.0% and 84.0%, respectively. The safety profile of nilotinib in pediatric patients was generally comparable with the known safety profile in adults, although cardiovascular events were not observed in this study, and hepatic laboratory abnormalities were more frequent; no new safety signals were identified. In summary, nilotinib demonstrated efficacy and a manageable safety profile in pediatric patients with Ph+ CML-CP. This trial was registered at www.clinicaltrials.gov as #NCT01844765.

Chronic myeloid leukemia (CML) is rare in children and accounts for ≤15% of all myeloid leukemia cases. When we initiated this study with nilotinib, imatinib was the only tyrosine kinase inhibitor indicated for pediatric patients with Philadelphia chromosome–positive (Ph+) CML in chronic phase (CP); alternative treatment options were needed, particularly for patients who developed resistance or intolerance (R/I) to imatinib. This phase 2 study enrolled pediatric patients with either Ph+CML-CP R/I to imatinib or dasatinib or newly diagnosed Ph+CML-CP. Data presented are from analyses with minimum follow-up of up to 24 cycles (1 cycle is 28 days). Fifty-nine patients with Ph+CML-CP were enrolled, and 58 were treated (R/I, n = 33; newly diagnosed, n = 25). Major molecular response (MMR) rate at cycle 6 in the R/I cohort was 39.4% (primary end point); 57.6% of patients achieved or maintained MMR and 81.8% achieved or maintained complete cytogenetic response (CCyR) by 24 cycles. In patients with newly diagnosed disease, rates of MMR by cycle 12 and CCyR at cycle 12 were 64.0% each (primary end points); by cycle 24, cumulative MMR and CCyR rates were 68.0% and 84.0%, respectively. The safety profile of nilotinib in pediatric patients was generally comparable with the known safety profile in adults, although cardiovascular events were not observed in this study, and hepatic laboratory abnormalities were more frequent; no new safety signals were identified. In summary, nilotinib demonstrated efficacy and a manageable safety profile in pediatric patients with Ph+CML-CP. This trial was registered at www.clinicaltrials.govas #NCT01844765.

Recovery of immunity is delayed in recipients of T-depleted grafts. Adoptive transfer of memory T-cells may improve immune response to common pathogens. A cohort of 53 patients with malignant (n= 36) and non-malignant conditions (n= 17) received TCR alpha/beta depleted grafts from haploidentical (n= 25) or MUD (n= 28) donors. Donor lymphocytes were depleted of CD45RA-positive cells. At a median of 48 days after transplantation, patients received DLI at 25 × 103/kg CD3 cells from haploidentical or 100 × 103/kg CD3 from MUD donors. Up to 3 doses of donor lymphocytes were administered at monthly intervals, escalating to 100 × 103/kg in haploidentical transplants and 300 × 103/kg in MUD transplants. At a median follow-up of 23 months, the cumulative incidence of de novo acute GVHD after DLI is 2% (1 of 43), while the rate of reactivation of preexisting aGVHD was 50% (5 of 10). The transplant-related mortality is 6%. The overall survival rates are 80% and 88% in malignant and non-malignant conditions, respectively. Among patients with absent CMV-specific immune reactivity at baseline (n= 31) expansion of CMV-specific T-cells was demonstrated in 20 (64.5%) within 100 days. Infusions of low dose donor memory T-lymphocytes are safe and constitute a simple measure to prevent infections in the setting of alpha/beta T cell-depleted transplantation.

Introduction

Introduction: Relapse remains a significant challenge in the management of high-risk B-cell acute lymphoblastic leukemia (B-ALL) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Existing post-transplant relapse prevention strategies for high-risk B-ALL patients after transplantation, particularly in cases of Philadelphia chromosome-negative B-ALL, have limitations and suboptimal efficacy. This study aims to evaluate the efficacy and safety profile of prophylactic or preemptive infusion of donor-derived CD19 chimeric antigen receptor T (CAR-T) cells in high-risk B-ALL patients after allo-HSCT.

αβT-cell-depleted allogeneic hematopoietic cell transplantation holds promise for the safe and accessible therapy of both malignant and non-malignant blood disorders. Here we employed molecular barcoding normalized T-cell receptor (TCR) profiling to quantitatively track T-cell immune reconstitution after TCRαβ-/CD19-depleted transplantation in children. We demonstrate that seemingly early reconstitution of αβT-cell counts 2 months after transplantation is based on only several hundred rapidly expanded clones originating from non-depleted graft cells. In further months, frequency of these hyperexpanded clones declines, and after 1 year the observed T-cell counts and TCRβ diversity are mostly provided by the newly produced T cells. We also demonstrate that high TCRβ diversity at day 60 observed for some of the patients is determined by recipient T cells and intrathymic progenitors that survived conditioning regimen. Our results indicate that further efforts on optimization of TCRαβ-/CD19-depleted transplantation protocols should be directed toward providing more efficient T-cell defense in the first months after transplantation.

IntroductionYoung patients with idiopathic aplastic anemia (AA) respond better to immunosuppressive therapy (IST) but the long-term outcome is suboptimal with non-response in 30% of patients as well as significant risks of relapse, ciclosporine (CSA) dependence and clonal evolution. Excellent results of up-front unrelated donor (UD) hematopoietic stem cell transplantation (HSCT) have been reported in a cohort of 29 children with idiopathic AA using an Alemtuzumab-based regimen, with low Graft versus Host Disease (GvHD) rates and only 1 death (Dufour C, BJH 2015). We took advantage of the SAAWP registry of the European Blood and Marrow Transplantation (EBMT) to analyze the outcomes of 65 young patients who received up-front UD HSCT in Europe.

We evaluated the depletion of TCR-alpha/beta cells from the graft of children with high-risk AML, who received transplantation from unrelated (n=20) and haploidentical donors (n=13). The preparative regimen included treosulfan, melphalan, fludarabine and anti-thymocyte globulin. Grafts were PBSC engineered by TCR-alpha/beta and CD19 depletion. The graft contained a median of 9 × 106/kg of CD34+ and 20 × 103/kg of αβ-T cells. Post-transplant immune suppression included tacrolimus till day +30 and Mtx in 21 patients, tacrolimus in 5, Mtx in 2 and no prophylaxis in 5 patients. Sixteen patients received native or TCR-alpha/beta-depleted donor lymphocytes at a median of 47 (40–204) days. Median follow-up is 1.76 years. Primary engraftment was achieved in 33 patients (100%). Cumulative incidence of acute GvHD (aGvHD) grade 2–3 was 39 (26–60)%, half of them had skin-only aGvHD. Cumulative incidence of chronic GvHD was 30(18–50)%. Transplant-related mortality is 10(4–26)%. Event-free survival (EFS) is 60(43–76)% and overall survival (OS) is 67(50–84)% at 2 years. In a subgroup of patients, who received transplantation in CR, EFS is 66(48–84)% and OS−72(53–90)% at 2 years. Our data suggest that TCR-alpha/beta and CD19 depletion is a robust method of graft manipulation, which can be used to engineer grafts for children with AML

Introduction

We evaluated frequencies of NPM1, FLT3, c-KITmutations in childhood acute myeloid leukemia (AML) in Russia and assessed prognostic relevance of the mutations. RNA and DNA were extracted from bone marrow samples of 186 (106 male and 80 female) pediatric patients younger than 17 year with de novo AML. Mutations and chromosomal rearrangements were detected by sequencing of a corresponding gene. NPM1mutations were found in 5.2, FLT3mutations in 12.1, c-KITmutations in 3.7 of the patients. NPM1 mutations were associated with the absence of chromosomal aberrations (P=0.007) and FLT3ITD (P=0.018). New data on incidence of c-KITmutations in various AML subtypes as well as new variations of c-KITmutations in the exon 8 are presented. The results are compared to previously published studies on NPM1, FLT3, c-KITmutations in various populations. No statistically significant differences in survival rates between groups with or without of FLT3, NPM1, c-KITmutations were found (P>0.05). Meanwhile, 4-year overall survival rates were higher in patients having NPM1 mutations comparing with NPM1WT patients (100 vs. 50) and in patients having FLT3mutations comparing with FLT3WT patients (70 vs. 50). The data presented contribute to knowledge on incidence and prognostic significance of the mutations in pediatric AML.

•Nilotinib treatment demonstrated sustained long-term efficacy in pediatric patients with CML-CP•The overall benefit-risk assessment of nilotinib in pediatric patients with CML remains favorable making it a valuable treatment option

The long-term outcome of allogeneic hematopoietic stem cell transplantation (HSCT) in chemorefractory acute myeloid leukemia (AML) remains suboptimal because of a high relapse rate. Enhancement of conditioning regimens by the incorporation of targeted anti-leukemia agents is a potential approach to improve the efficacy of HSCT. In a pilot trial and extended access cohort, we evaluated the safety and potential value of adding combinations of venetoclax and daratumumab to a preparative regimen among children with chemorefractory acute myeloid leukemia grafted with αβ T-cell–depleted peripheral blood stem cells. All 20 patients had active disease status of AML at the time of transplantation. The preparative regimen included myeloablative conditioning based on either total body irradiation or treosulfan. A haploidentical related donor was used as a graft source for all patients. Engraftment was not compromised, and no excess toxicity was noted. Minimal residual disease–negative complete remission was achieved in 17 patients (85%). The cumulative incidence of grade II to IV acute graft-versus-host disease (GVHD) was 17%, and the cumulative incidence of chronic GVHD was 7%. At 2 years, nonrelapse mortality was 10%, relapse incidence was 46%, event-free survival was 44%, and overall survival was 65%. Our data show the possibility of safely adding targeted agents to conditioning regimens; however, no evidence of a significant improvement in long-term transplantation outcomes in this cohort of patients was observed.

We compared the efficacy and safety of eltrombopag (ELTR) combined with immunosuppressive therapy (IST) and IST alone in treatment-naïve children with severe (SAA) and very severe (vSAA) aplastic anemia. Ninety-eight pediatric patients were randomized to receive horse antithymocyte globulin and cyclosporin A with (n=49) or without (n=49) ELTR. The primary endpoint was the overall response rate (ORR) at 4 months. After 4 months, nonresponders were crossed over to the alternative group. In all patients, the ORR in ELTR+IST and IST groups was similar (65% vs. 53%, p=0.218); however, the complete response (CR) rate was significantly higher in ELTR+IST group (31% vs. 12%, p=0.027). In severity subgroups, the ORR was 89% vs. 57% (p=0.028) in favor of IST+ELTR in SAA, but it did not differ in patients with vSAA (52% vs. 50%, p=0.902). At 6 months after the crossover, 61% of initial ELTR(-) patients achieved a response compared to 17% of initial ELTR(+) patients (p=0.016). No significant difference in ELTR+IST and IST groups was observed in the 3-year OS (89% vs. 91%, p=0.673) or the 3-year EFS (53% vs. 41%, p=0.326). There was no unexpected toxicity related to ELTR. Adding ELTR to standard IST was well tolerated and increased the CR rate. The greatest benefit from ELTR combined with IST was observed in patients with SAA, but not in those with vSAA. The second course of IST resulted in a high ORR in initial ELTR(-) patients who added ELTR and had limited efficacy among patients who received ELTR upfront. Clinicaltrials.gov#NCT03413306.

Introduction