Relapsed Acute Lymphoblastic Leukemia (ALL) is among the most common causes of cancer-associated deaths in children. However, little is known about the implications of deviations from ALL treatment protocols on survival rates. The present study elucidates the various characteristics of treatment deviations in children with relapsed ALL included in the ALL-REZ BFM 2002 (i.e., Relapse Berlin-Frankfurt- Münster) trial and determines their prognostic relevance for relapse and death rates. Among 687 patients, 100 were identified with treatment deviations, further classified, and examined by occurrence time, cause and type. Protocol deviation was considered a time-dependent variable and its impact on Disease Free Survival (DFS) and Overall Survival (OS) was examined using the time-dependent model Mantel Byar. Five years after the relapse diagnosis, deviations were significantly related to both inferior DFS (38

BACKGROUND:Quantitative measurement of minimal residual disease (MRD) is the "gold standard" for estimating the response to therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Nevertheless, the speed of the MRD response differs for different cytogenetic subgroups. Here we present results of MRD measurement in children with BCP-ALL, in terms of genetic subgroups with relation to clinically defined risk groups. METHODS:A total of 485 children with non-high-risk BCP-ALL with available cytogenetic data and MRD studied at the end-of-induction (EOI) by multicolor flow cytometry (MFC) were included. All patients were treated with standard-risk (SR) of intermediate-risk (ImR) regimens of "ALL-MB 2008" reduced-intensity protocol. RESULTS AND DISCUSSION:Among all study group patients, 203 were found to have low-risk cytogenetics (ETV6::RUNX1 or high hyperdiploidy), while remaining 282 children were classified in intermediate cytogenetic risk group. For the patients with favorable and intermediate risk cytogenetics, the most significant thresholds for MFC-MRD values were different: 0.03% and 0.04% respectively. Nevertheless, the most meaningful thresholds were different for clinically defined SR and ImR groups. For the SR group, irrespective to presence/absence of favorable genetic lesions, MFC-MRD threshold of 0.1% was the most clinically valuable, although for ImR group the most informative thresholds were different in patients from low-(0.03%) and intermediate (0.01%) cytogenetic risk groups. CONCLUSION:Our data show that combining clinical risk factors with MFC-MRD measurement is the most useful tool for risk group stratification of children with BCP-ALL in the reduced-intensity protocols. However, this algorithm can be supplemented with cytogenetic data for part of the ImR group.

The bispecific T cell-binding antibody blinatumomab (CD19/CD3) is widely and successfully used for the treatment of children with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Here, we report the efficacy of a single course of blinatumomab instead of consolidation chemotherapy to eliminate minimal residual disease (MRD) and maintain stable MRD-negativity in children with primary BCP-ALL.Between February 2020 and November 2022, 177 children with non-high-risk BCP-ALL were enrolled in the ALL-MB 2019 pilot study (NCT04723342). Patients received the usual risk-adapted induction therapy according to the ALL-MB 2015 protocol. Those who achieved a complete remission at the end of induction (EOI) received treatment with blinatumomab immediately after induction at a dose of 5 μg/m2/day for 7 days and 21 days at a dose of 15 μg/m2/day, followed by 12 months of maintenance therapy. MRD was measured using multicolor flow cytometry (MFC) at the EOI, then immediately after blinatumomab treatment, and then four times during maintenance therapy at 3-month intervals.All 177 patients successfully completed induction therapy and achieved a complete hematological remission. In 174 of these, MFC-MRD was measured at the EOI. 143 patients (82.2%) were MFC-MRD negative and the remaining 31 patients had varying degrees of MFC-MRD positivity.MFC-MRD was assessed in all 176 patients who completed the blinatumomab course. With one exception, all patients achieved MFC-MRD negativity after blinatumomab, regardless of the MFC-MRD score at EOI. One adolescent girl with high MFC-MRD positivity at EOI remained MFC-MRD positive. Of 175 patients who had completed 6 months of maintenance therapy, MFC-MRD data were available for 156 children. Of these, 155 (99.4%) were MFC-MRD negative. Only one boy with t(12;21) (p13;q22)/ETV6::RUNX1 became MFC-MRD positive again. The remaining 174 children had completed the entire therapy. MFC-MRD was examined in 154 of them, and 153 were MFC-MRD negative. A girl with hypodiploid BCP-ALL showed a reappearance of MFC-MRD with subsequent relapse.In summary, a single 28-day course of blinatumomab immediately after induction, followed by 12 months of maintenance therapy, is highly effective in achieving MRD-negativity in children with newly diagnosed non-high risk BCP-ALL and maintaining MRD-negative remission at least during the treatment period.

Sequential monitoring of minimal residual disease (MRD) by molecular techniques or multicolor flow cytometry (MFC) has emerged over the past two decades as the primary tool to optimize treatment in pediatric B‐cell precursor acute lymphoblastic leukemia (BCP‐ALL). The aim of our study was to compare the prognostic power of repeated MFC–MRD measurement with single‐point MRD assessment in children with BCP‐ALL treated with the reduced‐intensity protocol ALL‐MB 2008. Data from consecutive MFC–MRD at day 15 and day 36 (end of induction, EOI) were available for 507 children with Philadelphia‐negative BCP‐ALL. They were stratified into standard risk (SR, n = 265), intermediate risk (ImR, n = 211), and high risk (HR, n = 31) according to the initial clinical characteristics defined in the ALL‐MB 2008 protocol. Quantitative (relative to quantitative thresholds) and kinetic (logarithmic reduction) assessments of MFC–MRD at both time points effectively separated patients into three groups with different risk of recurrence. On the other hand, starting with low (for the SR group) and moderate (for the ImR group) induction therapy, a single MFC–MRD measurement at EOI proved sufficient to unequivocally identify patients in whom this therapy is highly effective and distinguish them from those who cannot be successfully treated with such therapy. Therefore, initiating treatment with low or moderate treatment from the start, together with careful consideration of initial clinical risk factors and just one EOI–MFC–MRD measurement is simple, inexpensive, and entirely sufficient for treatment optimization. Furthermore, for a large proportion of patients, this approach allows better adjustment, in particular also reduction of therapy intensity than sequential MRD measurements.

The aim of this study was to present the diagnostic and outcome characteristics of infants with germline status of KMT2A gene (KMT2A‐g) B‐cell precursor acute lymphoblastic leukemia (BCP‐ALL) treated consistently according to the MLL‐Baby protocol, a moderate‐intensity protocol. Of the 139 patients enrolled in the MLL‐Baby study, 100 (71.9%) carried different types of rearranged KMT2A (KMT2A‐r), while the remaining 39 infants (28.1%) had KMT2A‐g. KMT2A‐g patients were generally older (77% older than 6 months), less likely to have a very high white blood cell count (greater than 100 × 109/L), less likely to be central nervous system (CNS)‐positive, and more likely to be CD10‐positive. The 6‐year event‐free survival and overall survival rates for all 39 patients were 0.74 (standard error [SE] 0.07) and 0.80 (SE 0.07), respectively. Relapse was the most common adverse event (n = 5), with a cumulative incidence of relapse (CIR) of 0.13 (SE 0.06), while the incidence of a second malignancy (n = 1) and death in remission (n = 3) was 0.03 (SE 0.04) and 0.08 (SE 0.04), respectively. None of the initial parameters, including genetics and the presence of recently described fusions of NUTM1 and PAX5 genes, was able to distinguish patients with different outcomes. Only rapidity of response, measured as minimal residual disease (MRD) by flow cytometry, showed a statistically significant impact. Moderate‐intensity therapy, as used in the MLL‐Baby protocol in infants with KMT2A‐g BCP‐ALL, yields results comparable to other infant studies. Patients with a slow multicolor flow cytometry (MFC)‐MRD response should be subjected to advanced therapies, such as targeted or immunotherapies.

Acute lymphoblastic leukemia (ALL) represents the most frequent malignancy in children, and relapse/refractory (r/r) disease is difficult to treat, both in children and adults. In search for novel treatment options against r/r ALL, we studied inhibitor of apoptosis proteins (IAP) and Smac mimetics (SM). SM‐sensitized r/r ALL cells towards conventional chemotherapy, even upon resistance against SM alone. The combination of SM and chemotherapy‐induced cell death via caspases and PARP, but independent from cIAP‐1/2, RIPK1, TNFα or NF‐κB. Instead, XIAP was identified to mediate SM effects. Molecular manipulation of XIAP in vivo using microRNA‐30 flanked shRNA expression in cell lines and patient‐derived xenograft (PDX) models of r/r ALL mimicked SM effects and intermediate XIAP knockdown‐sensitized r/r ALL cells towards chemotherapy‐induced apoptosis. Interestingly, upon strong XIAP knockdown, PDX r/r ALL cells were outcompeted in vivo, even in the absence of chemotherapy. Our results indicate a yet unknown essential function of XIAP in r/r ALL and reveal XIAP as a promising therapeutic target for r/r ALL. Smac mimetics sensitize relapsed/refractory acute leukemia (r/r ALL) cell lines towards chemotherapy, independently from TNFα, RIPK1, NFκB and cIAP1/2 signaling. Knockdown in PDX models shows that XIAP harbors an essential function in vivo and represents an important therapeutic target for r/r ALL. Smac mimetics sensitize relapsed/refractory acute leukemia (r/r ALL) cell lines towards chemotherapy, independently from TNFα, RIPK1, NFκB and cIAP1/2 signaling. Knockdown in PDX models shows that XIAP harbors an essential function in vivo and represents an important therapeutic target for r/r ALL.

The excellent results of posttransplant cyclophosphamide in decreasing graft-versus-host disease (GVHD) after haploidentical (HI) allogeneic transplant have challenged current donor selection algorithms.We compared outcomes after matched sibling (MSD) versus alternative donor transplant using identical graft-versus-host disease (GVHD) prophylaxis including posttransplant cyclophosphamide (PTCy. Endpoints included engraftment, time outside of the hospital in the first 100 days after transplant, overall survival (OS), non-relapse mortality (NRM) and percentage of patients disease-free and off immunosuppression (DFOI) at one year and at the last follow-up.There were significant differences at baseline between matched donor versus HI donor transplants with higher disease-risk index (DRI), more female-to-male donor recipient pairs and a higher percentage of Black patients in the HI group. Engraftment and time out of the hospital favored MSD and matched unrelated donor transplants. Multivariate analysis showed that high DRI and Black race were associated with decreased survival and Black race was associated with a higher NRM.With the use of PTCy, our results support current donor selection algorithms. The finding of decreased survival and increased NRM in Black patients requires confirmation in a larger number of patients as well as the development of mitigation strategies.

Measurement of minimal residual disease (MRD) with multicolor flow cytometry (MFC) has become an important tool in childhood acute lymphoblastic leukemia (ALL), mainly to identify rapid responders and reduce their therapy intensity. Protocols of the Moscow–Berlin (MB) group use a comparatively low (for standard risk; SR) or moderate (for intermediate risk; ImR) treatment intensity from the onset, based on initial patient characteristics. Recently, we reported that 90

Abstract Introduction: Acute lymphoblastic leukemia (ALL) is the most common cancer affecting children and its cure rates are close to 90%. Nevertheless, relapsed ALL is still a major cause of cancer-associated deaths in children. Therefore, the multicenter trial Acute Lymphoblastic Leukemia-Relapse Study of the Berlin-Frankfurt-Münster Group (ALL-REZ BFM) 2002 was designed to improve the prognosis of children with relapsed ALL by introducing new chemotherapy elements. Little is known though about the prognostic relevance of deviations from the ALL protocols. This study aimed to investigate the characteristics of such protocol deviations and to determine their prognostic relevance for the relapsed disease. Methods: We performed a retrospective analysis of 686 children and adolescents up to 18 years of age with first relapse of ALL who were enrolled between 2002 and 2012 in the ALL-REZ BFM 2002 Study. Deviations were identified in terms of time and type. In order to investigate the prognostic importance of the time delay, the 90th percentile of delays between defined treatment elements (i.e. 15.5 days) was used as a cut-off point. Furthermore, deviations were categorized as avoidable (logistics, family/PI decisions) and non-avoidable (clear medical indication). The protocol deviation occurred during the course of therapy was therefore considered as a time-dependent variable. Disease-free survival, (DFS, induction failures excluded) and OS were analyzed using Kaplan-Meier estimate, log-rank test, Mantel-Byar test and Cox/logistic regression (univariate and multivariate analyses). Results: A total of 587 patients (86%) received the protocol therapy, whereas 99 patients (14%) underwent deviations during their treatment. Baseline characteristics were compared in both groups (Table 1). Deviations were categorized as: change of chemotherapy in 48% of the patients (n=47/99), stop of chemotherapy in 10 % (n=10/99), non-protocol compliant reaction to MRD findings in 28% (n=28/99) and change of radiation treatment in 14% (n=14/99). The cumulative incidence of protocol deviation was 6% and 15.5% at 3 and 9 months, respectively (Figure 1). The remission rate of patients with protocol deviation during induction was slightly lower compared to patients without such deviation (24/29, 83% vs. 579/657, 88%; P=0.38). The estimated 5-year probabilities of DFS and OS between the patients treated according to protocol therapy and those with deviations were significantly different (pDFS, Protocol therapy: 0.61 ± 0.02 vs. Deviation: 0.38 ± 0.05, P < 0.001; pOS, Protocol: 0.70 ± 0.02 vs. Deviation: 0.57 ± 0.05, P < 0.001; Figure 2, 3). In multivariate analyses protocol deviation, time point of relapse and immunophenotype turned out to be independent prognostic factors of the DFS (Table2). The hazard ratio of the protocol deviation was significant only in patients with the late relapse, whereas in patients with early/very early relapse no significant prognostic effect could be found [late (n=40): HR=2.53, 95%CI 1.53-4.21, P<0.001; early (n=29): HR=1.49, 95%CI 0.88-2.51, P=0.13; very early (n=25): HR=1.50, 95%CI 0.84-2.66, P=0.17]. Moreover, DFS probabilities were comparable for avoidable (n=63) and non-avoidable (n=31) deviations (0.43 ± 0.07 vs. 0.40 ± 0.09, P=0.9; Non avoidable: HR=1.19, 95%CI=0.68-2.10, P= 0.53). In terms of the time-related deviations, the extent of the delays between induction and beginning of consolidation therapy was not significantly associated with the DFS [≤90th percentile (n=319/603); pDFS: =0.60 ± 0.02 vs. >90th percentile (n=36/603); pDFS: 0.56 ± 0.08, P=0.3]. Treatment delays during other phases of the protocol were also not related to the outcome. Conclusion: While protocol deviations did not significantly affect remission rates in this study, they were significantly related to inferior DFS. Since a relevant part of the protocol deviations could be classified as avoidable, strict protocol compliance should lead to improved outcomes. The prognostic impact of protocol deviations was in particular relevant in patients with late relapse with generally rather chemosensitive diseases and better prognosis. In this analysis, treatment delays did not influence the outcome. Figure 1 Figure 1. Disclosures von Stackelberg: Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Miltenyi: Consultancy, Honoraria.

Children with other extramedullary relapse of acute lymphoblastic leukemia are currently poorly characterized. We aim to assess the prevalence and the clinical, therapeutic and prognostic features of extramedullary localizations other than central nervous system or testis in children with relapse of acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) treated on a relapsed ALL protocol.PATIENTS AND METHODS:Patients with relapse of ALL and LBL, treated according to the multicentric ALL-REZ BFM trials between 1983 and 2015, were analyzed for other extramedullary relapse (OEMR) of the disease regarding clinical features, treatment and outcome. Local treatment/irradiation has been recommended on an individual basis and performed only in a minority of patients.RESULTS:A total of 132 out of 2323 (5.6%) patients with ALL relapse presented with an OEMR (combined bone marrow relapse n = 78; isolated extramedullary relapse n = 54). Compared to the non-OEMR group, patients with OEMR had a higher rate of T-immunophenotype (p < 0.001), a higher rate of LBL (p < 0.001) and a significantly different distribution of time to relapse, i.e., more very early and late relapses compared to the non-OEMR group (p = 0.01). Ten-year probabilities of event-free survival (pEFS) and overall survival (pOS) in non-OEMR vs. OEMR were 0.38 ± 0.01 and 0.32 ± 0.04 (p = 0.0204) vs. 0.45 ± 0.01 and 0.37 ± 0.04 (p = 0.0112), respectively. OEMRs have been classified into five subgroups according to the main affected compartment: lymphatic organs (n = 32, 10y-pEFS 0.50 ± 0.09), mediastinum (n = 35, 10y-pEFS 0.11 ± 0.05), bone (n = 12, 0.17 ± 0.11), skin and glands (n = 21, 0.32 ± 0.11) and other localizations (n = 32, 0.41 ± 0.09). Patients with OEMR and T-lineage ALL/LBL showed a significantly worse 10y-pEFS (0.15 ± 0.04) than those with B-Precursor-ALL (0.49 ± 0.06, p < 0.001). Stratified into standard risk (SR) and high risk (HR) groups, pEFS and pOS of OEMR subgroups were in the expected range whereas the mediastinal subgroup had a significantly worse outcome. Subsequent relapses involved more frequently the bone marrow (58.4%) than isolated extramedullary compartments (41.7%). In multivariate Cox regression, OEMR confers an independent prognostic factor for inferior pEFS and pOS.CONCLUSION:OEMR is adversely related to prognosis. However, the established risk classification can be applied for all subgroups except mediastinal relapses requiring treatment intensification. Generally, isolated OEMR of T-cell-origin needs an intensified treatment including allogeneic stem cell transplantation (HSCT) as a curative approach independent from time to relapse. Local therapy such as surgery and irradiation may be of benefit in selected cases. The indication needs to be clarified in further investigations.

Purpose Neuroblastoma (NB) is the most frequent extracranial tumor in children. The detection of bone marrow (BM) involvement is crucial for correct staging and risk-adapted treatment. We compared three methods regarding the detection of NB involvement in BM. Methods Eighty-one patients with NB were included in this retrospective study. BM samples were obtained at designated time points at study entry and during treatment or follow-up. The diagnostic tools for BM analysis included cytomorphology (CM), flow cytometry (FCM) and automatic immunofluorescence plus fluorescence in situ hybridization (AIPF). Results We analyzed 369 aspirates in 81 patients in whom AIPF, CM, and FCM were simultaneously available. During the observation period, NB cells were detected in 86/369 (23.3%) cases, by CM in 32/369 (8.7%), by FCM in 52 (14.1%), and by AIPF in 72 (19.5%) samples. AIPF and/or FCM confirmed all positive results obtained in CM and detected 11 additional positive BM aspirates in 294 CM negative samples ( p < 0,001). Survival of patients with BM involvement at study entry identified solely by FCM/AIPF was 17.4% versus 0% for patients in whom BM involvement was already identified by CM. Conclusion The combination of AIPF/FCM yielded the highest detection rate of NB cells in BM. AIPF was the single, most sensitive method in detecting these cells. Although CM did not provide any additional positive results, it is still a useful, readily available and cost-effective tool. The prognostic significance of FCM and AIPF should be confirmed in a prospective study with a larger number of patients.

Targeting the pan-B-lymphocyte antigen CD19 with the bispecific T-cell engager blinatumomab is one of the modern ways of treating acute lymphocytic B-cell precursor leukaemia (BCP-ALL). This drug has been very successful in treating patients with relapsed/refractory (R/R) disease, but it has recently been shown that blinatumomab is also effective in eradicating minimal residual disease (MRD) in patients with relapsed or primary BCP-ALL. Loss of the target molecule is one of the key mechanisms for leukaemia cells to escape the selective pressure of blinatumomab. The resulting possible CD19 negativity interferes with MRD monitoring by multicolour flow cytometry (MFC), which is usually based on analysis of the CD19-positive compartment. On the other hand, the use of other early B-line antigens [CD22, CD24, CD10, intracellular (i) CD79a] instead of CD19 for primary B-cell gating, such as to improve the MFC-MRD technique in the case of CD19-targeted treatment, could lead to errors in the interpretation of the immunophenotype of normal haematopoietic cells. Recently we have shown that after CD19 targeting in children with R/R BCP-ALL by either blinatumomab or chimaeric antigen receptor (CAR)-T cells, a relative expansion of normal very early CD19-negative BCPs can be observed. Due to the specific immunophenotype, which is very different from that of mature CD19-positive BCPs, these normal cells could be misinterpreted during the MFC-MRD assessment as developing a CD19-negative relapse. MRD studies are central to evaluating the effectiveness of targeted treatment. Therefore, the possible detection of such CD19negative normal precursors in the majority (almost 60–70%) of children after CD19-directed immunotherapy should be viewed as one of the cornerstones of MFC-MRD monitoring after blinatumomab therapy. At the same time, the inclusion of blinatumomab in treatment protocols for primary ALL requires additional assessment of the normal antigen expression pattern of bone marrow (BM) cells. It should be borne in mind that regeneration of BM cells may be more active during first-line therapy for ALL compared to heavily pre-treated R/R patients. In this study, we wanted to investigate the incidence and distribution of early CD19-negative BCPs in children with primary ALL after treatment with blinatumomab. Between February 2020 and March 2021, fifty consecutive children (Table SI) with primary BCP-ALL were enrolled in the pilot study ALL-MB 2019 (NCT04723342). This protocol was developed for the treatment of children and adolescents where immunotherapy with blinatumomab immediately followed the induction therapy. After achieving complete remission on the end of induction (EOI), a four-week course of blinatumomab is given, followed by 12 months of maintenance therapy. At the time of the data analysis, 48 of 50 children had completed the blinatumomab courses and were therefore included in the analysis. According to the protocol, BM samples were collected immediately after completion of CD19 targeting (n = 48) and then after three (n = 26), six (n = 19), nine (n = 12) and 12 (n = 7) months of maintenance. The MFC-MRD detection was carried out according to the method described previously, adapted to possible CD19 loss. Immunophenotype of BM cells was studied by 11colour MFC using a three-laser CytoFLEX flow cytometer (Beckman Coulter Inc, Brea, CA, USA). The MRD-targeted combinations contained fluorochrome-conjugated antibodies against CD45, CD19, CD10, CD38, CD34, CD58, CD20, CD22, CD24 and iCD79a (Table SII). CD19-negative B-cell precursors were gated as described previously. All BM samples obtained after completion of blinatumomab were MFC-MRD-negative, including those from patients who were MFC-MRD-positive at EOI (n = 7, median MFC-MRD 0 030%, range 0 001–0 166%). On the other hand, CD19-negative BCPs were detected in all 48 samples obtained at the end of the blinatumomab course (median 0 182%, range 0 008–0 476% among all nucleated cells). These cells were also found in all patients at all timepoints during maintenance therapy (Fig. 1). The quantitative level of these CD19-negative BCPs did not differ between time points, which was remarkable throughout the maintenance therapy (Fig. 2A). In contrast, more mature CD19-positive normal BCPs were only detectable in 31 of 48 samples (64 6%) obtained at the end of blinatumomab treatment (median 0 020%, range 0 009–3 061%). In contrast to the CD19-negative precursors, the level of CD19-positives increased significantly during the first three months of Correspondence

Aim: Outcomes of children with high-risk (HR) relapsed acute lymphoblastic leukaemia (ALL) (N = 393), recruited to ALLR3 and ALL-REZ BFM 2002 trials, were analysed. Minimal residual disease (MRD) was assessed after induction and at predetermined time points until haematopoietic stem cell transplantation (SCT). Methods: Genetic analyses included karyotype, copy-number alterations and mutation analyses. Ten-year survivals were analysed using Kaplan-Meier and Cox models for multivariable analyses. Results: Outcomes of patients were comparable in ALLR3 and ALL-REZ BFM 2002. The eventfree survival of B-cell precursor (BCP) and T-cell ALL (T-ALL) was 22.6% and 26.2% (P = 0.94), respectively, and the overall survival (OS) was 32.6% and 28.2% (P = 0.11), respectively. Induction failures (38%) were associated with deletions of NR3C1 (P = 0.002) and BTG1 (P = 0.03) in BCP-ALL. The disease-free survival (DFS) and OS in patients with good vs poor MRD responses were 57.4% vs 22.6% (P < 0.0001) and 57.8% vs 32.0% (P = 0.0004), respectively. For BCP- and T-ALL, the post-SCT DFS and OS were 42.1% and 56.8% (P = 0.26) and 51.6% and 55.4% (P = 0.67), respectively. The cumulative incidences of post-SCT relapse for BCP- and T-ALL were 36.9% and 17.8% (P = 0.012) and of death were 10.7% and 25.5% (P = 0.013), respectively. Determinants of outcomes after SCT were acute graft versus host disease, preSCT MRD (>= 10(-3)), HR cytogenetics and TP53 alterations in BCP-ALL. Conclusion: Improvements in outcomes for HR ALL relapses require novel compounds in induction therapy to improve remission rates and immune targeted therapy after induction to maintain remission after SCT. (C) 2021 The Author(s). Published by Elsevier Ltd.

BACKGROUND:Neuroblastoma (NB) is the most frequent extracranial solid tumor in children. More than 50% of patients present with widespread (stage M) or refractory disease. In these patients, event-free and overall survival was improved by the addition of the anti-disialoganglioside antibody dinutuximab beta (DB) following multimodal conventional therapy. However, the prognosis of patients with refractory/relapsed NB remains poor. In the past decade, immunotherapy approaches with checkpoint inhibitors were approved for patients with certain malignant diseases such as melanoma or Hodgkin lymphoma. In preclinical models, DB resulted in an upregulation of the programmed cell death protein 1 (PD-1) checkpoint in NB cell lines and a combined treatment of DB with a murine anti-PD-1 checkpoint inhibitor showed a synergistic effect in a NB mouse model.CASE PRESENTATIONS:Two patients were admitted with refractory metastatic NB. In the 4-year-old girl, NB was diagnosed in 2013. She completed her first-line therapy with a first remission in 2015, but suffered a relapse in 2017. Treatment with chemotherapy and DB resulted in progressive disease after transient improvement. In the 17-year-old young man, NB was first diagnosed in April 2010. After two local relapses in 2011 and 2014, a metastatic relapse and a large abdominal tumor bulk were found in 2018. Despite transient improvement with multimodal therapy, progressive metastatic disease was observed in May 2019. Both patients had a satisfactory quality of life. Therefore, treatment with DB and nivolumab was performed-in the girl from October 2018 until August 2019, in the young man since June 2019. Tolerance to treatment was excellent. The girl continues to be in complete remission 6 months after therapy was stopped. In the young man, the soft tissue lesions disappeared completely, the skeletal lesions regressed substantially after 9 months of his still ongoing treatment.CONCLUSIONS:The combination of DB with the checkpoint inhibitor nivolumab led to complete and a very good partial remission in two patients with relapsed/refractory NB. Prospective trials are warranted to clarify the role of this novel approach in a larger number of patients.

Background Usually, central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL) is diagnosed by cytomorphology (CM) of cerebrospinal fluid (CSF) on cytospin slides. Multicolor flow cytometry (MFC) provides the opportunity to detect low numbers of leukemia cells undetectable by CM. The present study aimed at evaluating the clinical significance of MFC for the diagnosis of CNS involvement at initial manifestation of childhood ALL. Methods In 155 children with ALL, CSF samples were studied in parallel by CM and MFC. Patients were treated according to protocol ALL-MB-2008 for childhood ALL. The prognostic impact of the leukemia burden in CSF was determined categorizing the findings as positive/negative. In addition, the absolute blast cell count per 1 ml of CSF was studied as a continuous variable. Results CSF positivity was significantly more frequent using MFC compared with CM (35.3% vs. 15.3% of patients). The outcome of MFC-positive and MFC-negative patients was not different in clinically relevant patient risk groups—CNS1, standard and intermediate-risk groups. Using the quantitative approach, at the threshold level of 20 blasts per ml of CSF, patients could be divided into two groups with a significantly different outcome, irrespective of the clinical risk group, the type of CNS-directed therapy, and the CNS status determined by CM. Conclusions Our data do not support the concept of re-stratification and modification of therapy based on qualitative CSF investigation by MFC. However, MFC is a highly sensitive technique of CSF investigation improving the definition of CNS involvement in childhood ALL, and quantitative measurement of blast cells in CSF, if well-organized, can be a useful additional tool for stratification of patients in clinical trials.

RATIONALE:Tumor rupture and bleeding at initial presentation of infants with neuroblastoma (NBL) is a rare, but life threatening condition and challenge in pediatric oncology. Here, we report successful multidisciplinary management of an abdominal compartment syndrome as a result of tumor rupture and bleeding in an infant with bilateral high risk stage 4 NBL.PATIENT CONCERNS:The patient was admitted to a cooperating hospital with vomiting, failure to thrive and a large mass in the abdomen and was then referred to our center.DIAGNOSES:Stage 4 NBL with MYC-N amplification and 1p36 deletion was diagnosed in an 11 months old girl. Due to rapid and massive tumor growth she developed abdominal compression with renal failure, severe bleeding, and tumor lysis syndrome (TLS).INTERVENTIONS:Surgical decompression by enterostomy, local, and systemic bleeding control with platelets and coagulation factors, antiinfective and TLS therapy were effective in stabilizing the patient's condition. This allowed initiation of the multimodal antineoplastic treatment according to protocol NB 2004.OUTCOMES:Mechanical ventilation was stopped after 11 days, the abdominal wall was closed 3 months after the start of therapy, and treatment according to the protocol be started and successfully completed.LESSONS:Only the immediate, coordinated multidisciplinary intervention managed to overcome the life-threatening abdominal compartment syndrome and its associated problems, eventually enabling successful curative treatment.