Improving Stratification for Children With Late Bone Marrow B-Cell Acute Lymphoblastic Leukemia Relapses With Refined Response Classification and Integration of Genetics

PURPOSE

Minimal residual disease (MRD) helps to accurately assess when children with late bone marrow relapses of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) will benefit from allogeneic hematopoietic stem-cell transplantation (allo-HSCT). More detailed dissection of MRD response heterogeneity and the specific genetic aberrations could improve current practice.

PATIENTS AND METHODS

MRD was assessed after induction treatment and at different times during relapse treatment until allo-HSCT (indicated in poor responders to induction; MRD ≥ 10−3) for patients being treated for late BCP-ALL bone marrow relapses (n = 413; median follow-up, 9.4 years) in the ALL-REZ BFM 2002 trial/registry (ClinicalTrials.gov identifier: NCT00114348 ).

RESULTS

Patients with both good (MRD < 10−3) and poor responses to induction treatment reached excellent event-free survival (EFS; 72% v 65%) and overall survival (OS; 82% v 74%). Patients with MRD of 10−2 or greater after induction had reduced EFS (56%), and their MRD persisted until allo-HSCT more frequently than it did in patients with MRD of 10−3 or greater to less than 10−2 ( P = .037). Patients with 25% or more leukemic blasts after induction (early nonresponders) had the poorest prognosis (EFS, 22%). Interestingly, patients with MRD of 10−3 or greater before allo-HSCT (late nonresponders) still had an EFS of 50% and OS of 63%, which in principle justifies allo-HSCT in these patients. From a panel of selected candidate genes, TP53 alterations (frequency, 8%) were the only genetic alteration with independent prognostic value in any MRD-based response subgroup.

CONCLUSION

After induction treatment, MRD-based treatment stratification resulted in excellent survival in patients with late relapsed BCP-ALL. Prognosis could be further improved in very poor responders by intensifying treatment directly after induction. TP53 alterations can be defined as a novel genetic high-risk marker in all MRD response groups in late relapsed BCP-ALL. Here we identified early and late nonresponders to be considered as events in future trials.

Evaluation of Second Solid Cancers After Hematopoietic Stem Cell Transplantation in European Patients

Importance

Incidence and risk factors of second solid cancers (SSCs) that occur after hematopoietic stem cell transplantation (HSCT) are well documented. However, clinical outcome data of patients who developed an SSC after HSCT are limited.

Objective

To assess the outcome of patients with an SSC occurring after HSCT from the time of SSC diagnosis.

Design, Setting, and Participants

This cohort study used data of 4065 patients from 26 countries registered with the European Society for Blood and Marrow Transplantation, which has maintained clinical data since 1977 of patients who received a transplant. Information from all patients who underwent a transplant in Europe and had an SSC diagnosis between January 1, 2000, and December 31, 2014, was extracted. The cohort included patients with 18 different cancers. Data analysis was conducted from September 3, 2017, to March 17, 2018.

Main Outcomes and Measures

Median and 5-year age-standardized overall survival, causes of death, risk factor multivariate analysis using a clustered Cox proportional hazard regression model, and standardized mortality ratio were calculated for each of the 18 types of SSC.

Results

In total, 220 617 patients underwent a transplant, of whom only 4065 (1.8%) patients with a second solid cancer after HSCT were included in the study. Among the 4065 patients, 2321 (57.1%) were men and 1744 (42.9%) were women, with a mean (range) age of 59.1 (3.2-82.3) years at diagnosis of second solid cancer. The 5-year age-standardized overall survival was 47% (95% CI, 45%-49%). The 5-year overall survival rate after SSC diagnosis was poor for pancreas, lung, hepatobiliary, esophageal, brain, and gastric cancers, with a median survival between 0.6 and 1 year. The 5-year overall survival was intermediate for endometrial, colorectal, sarcomas, ovarian, bladder, oropharyngeal, and kidney cancers, with a median survival between 2 and 10 years. The 5-year overall survival was more favorable for melanoma, breast, prostate, cervix, and thyroid cancers, with a median survival of 10 or more years. Additional transplant-associated factors for mortality for patients treated with allogeneic HSCT were age at transplant, donor type, conditioning regimen, and graft-vs-host disease. In total, 1777 patients (43.7%) died, of which 1256 (74.8%) were from SSC, 344 (20.5%) from primary disease, and 79 (4.7%) from other causes. Standardized mortality ratio was higher, compared with de novo solid cancers, for melanoma, prostate, breast, kidney, bladder, colorectal, and endometrial cancers but not for the other cancers.

Conclusions and Relevance

The outcome of SSC is mainly dependent on the type of second cancer; thus, future studies should investigate the reasons the standardized mortality ratio is higher for some cancers to identify whether patients with these cancers should be treated differently and to help in screening and counseling patients who developed an SSC after HSCT.

Children and Adults with Refractory Acute Graft-versus-Host Disease Respond to Treatment with the Mesenchymal Stromal Cell Preparation "MSC-FFM"-Outcome Report of 92 Patients

(1) Background: Refractory acute graft-versus-host disease (R-aGvHD) remains a leading cause of death after allogeneic stem cell transplantation. Survival rates of 15% after four years are currently achieved; deaths are only in part due to aGvHD itself, but mostly due to adverse effects of R-aGvHD treatment with immunosuppressive agents as these predispose patients to opportunistic infections and loss of graft-versus-leukemia surveillance resulting in relapse. Mesenchymal stromal cells (MSC) from different tissues and those generated by various protocols have been proposed as a remedy for R-aGvHD but the enthusiasm raised by initial reports has not been ubiquitously reproduced. (2) Methods: We previously reported on a unique MSC product, which was generated from pooled bone marrow mononuclear cells of multiple third-party donors. The products showed dose-to-dose equipotency and greater immunosuppressive capacity than individually expanded MSCs from the same donors. This product, MSC-FFM, has entered clinical routine in Germany where it is licensed with a national hospital exemption authorization. We previously reported satisfying initial clinical outcomes, which we are now updating. The data were collected in our post-approval pharmacovigilance program, i.e., this is not a clinical study and the data is high-level and non-monitored. (3) Results: Follow-up for 92 recipients of MSC-FFM was reported, 88 with GvHD ≥°III, one-third only steroid-refractory and two-thirds therapy resistant (refractory to steroids plus ≥2 additional lines of treatment). A median of three doses of MSC-FFM was administered without apparent toxicity. Overall response rates were 82% and 81% at the first and last evaluation, respectively. At six months, the estimated overall survival was 64%, while the cumulative incidence of death from underlying disease was 3%. (4) Conclusions: MSC-FFM promises to be a safe and efficient treatment for severe R-aGvHD.

The Synergistic Use of IL-15 and IL-21 for the Generation of NK Cells From CD3/CD19-Depleted Grafts Improves Their ex vivo Expansion and Cytotoxic Potential Against Neuroblastoma: Perspective for Optimized Immunotherapy Post Haploidentical Stem Cell Transplantation

Neuroblastoma (NB) is the most common solid extracranial tumor in childhood. Despite therapeutic progress, prognosis in high-risk NB is poor and innovative therapies are urgently needed. Therefore, we addressed the potential cytotoxic capacity of interleukin (IL)-activated natural killer (NK) cells compared to cytokine-induced killer (CIK) cells for the treatment of NB. NK cells were isolated from peripheral blood mononuclear cells (PBMCs) by indirect CD56-enrichment or CD3/CD19-depletion and expanded with different cytokine combinations, such as IL-2, IL-15, and/or IL-21 under feeder-cell free conditions. CIK cells were generated from PBMCs by ex vivo stimulation with interferon-γ, IL-2, OKT-3, and IL-15. Comparative analysis of expansion rate, purity, phenotype and cytotoxicity was performed. CD56-enriched NK cells showed a median expansion rate of 4.3-fold with up to 99% NK cell content. The cell product after CD3/CD19-depletion consisted of a median 43.5% NK cells that expanded significantly faster reaching also 99% of NK cell purity. After 10–12 days of expansion, both NK cell preparations showed a significantly higher median cytotoxic capacity against NB cells relative to CIK cells. Remarkably, these NK cells were also capable of efficiently killing NB spheroidal 3D culture in long-term cytotoxicity assays. Further optimization using a novel NK cell culture medium and a prolonged culturing procedure after CD3/CD19-depletion for up to 15 days enhanced the expansion rate up to 24.4-fold by maintaining the cytotoxic potential. Addition of an IL-21 boost prior to harvesting significantly increased the cytotoxicity. The final cell product consisted for the major part of CD16⁻, NCR-expressing, poly-functional NK cells with regard to cytokine production, CD107a degranulation and antitumor capacity. In summary, our study revealed that NK cells have a significantly higher cytotoxic potential to combat NB than CIK cell products, especially following the synergistic use of IL-15 and IL-21 for NK cell activation. Therefore, the use of IL-15+IL-21 expanded NK cells generated from CD3/CD19-depleted apheresis products seems to be highly promising as an immunotherapy in combination with haploidentical stem cell transplantation (SCT) for high-risk NB patients.

Hematopoietic Stem Cell Transplantation Restores Naïve T-Cell Populations in Atm-Deficient Mice and in Preemptively Treated Patients With Ataxia-Telangiectasia

Background: Ataxia-telangiectasia (A-T) is a multisystem disorder with progressive cerebellar ataxia, immunodeficiency, chromosomal instability, and increased cancer susceptibility. Cellular immunodeficiency is based on naïve CD4⁺ and CD8⁺ T-cell lymphopenia. Hematopoietic stem cell transplantation (HSCT) offers a potential to cure immunodeficiency and cancer due to restoration of the lymphopoietic system. The aim of this investigation was to analyze the effect of HSCT on naïve CD4⁺ as well as CD8⁺ T-cell numbers in A-T.

Methods: We analyzed total numbers of peripheral naïve (CD45RA⁺CD62L⁺) and memory (CD45RO⁺CD62L⁻) CD4⁺ and CD8⁺ T-cells of 32 A-T patients. Naïve (CD62L^highCD44^low) and memory (CD62L^lowCD44^high) T-cells were also measured in Atm-deficient mice before and after HSCT with GFP-expressing bone marrow derived hematopoietic stem cells. In addition, we analyzed T-cells in the peripheral blood of two A-T patients after HLA-identic allogeneic HSCT.

Results: Like in humans, naïve CD4⁺ as well as naïve CD8⁺ lymphocytes were decreased in Atm-deficient mice. HSCT significantly inhibited thymic lymphomas and increased survival time in these animals. Donor cell chimerism increased up to more than 50% 6 months after HSCT accompanied by a significant increase of naïve CD4 and CD8 T-cell subpopulations, but not of memory T-cells. This finding was also identified in the blood of the A-T patients after HSCT.

Conclusion: HSCT seems to be a feasible strategy to overcome immunodeficiency and might be a conceivable strategy to avoid T-cell driven cancer in A-T at higher risk for malignancy. Naïve CD4 and CD8 T-cells counts are suitable markers for monitoring immune reconstitution post-HSCT. However, risks and benefits of HSCT in A-T have to be properly weighted.

Adoptive cellular immunotherapy for refractory childhood cancers: a single center experience

Prognosis of refractory childhood cancers despite multimodal treatment strategies remains poor. Here, we report a single center experience encountered in 18 patients with refractory solid malignancies treated with adoptive cellular immunotherapy (ACI) from haploidentical or matched donors following hematopoietic stem cell transplantation. While seven patients were in partial and six in complete remission (CR), five patients suffered from relapsed diseases at the time of ACI. 1.5-year probabilities of overall survival (OS) and progression-free survival (PFS) were 19.5% and 16.1% for all patients. Patients in CR showed estimated 1.5-year OS and PFS of 50.1% and 42.7%, respectively. CR was induced or rather sustained in ten children, with two still being alive 9.6 and 9.3 years after ACI. Naïve, central and effector memory T-cells correlated with responses. However, the majority of patients relapsed. Cumulative incidence of relapse was 79.8% at 1.5 years. Acute graft versus host disease (aGVHD) occurred in nine of 18 patients (50%) with aGVHD grade I–II observed in six (33%) and aGVHD grade III seen in three (17%) patients, manageable in all cases.

Altogether, study results indicate that donor-derived ACI at its current state offers palliation but no clear curative benefit for refractory childhood cancers and warrants further improvement.

Patient-reported quality of life after tisagenlecleucel infusion in children and young adults with relapsed or refractory B-cell acute lymphoblastic leukaemia: a global, single-arm, phase 2 trial

BACKGROUND

The ELIANA trial showed that 61 (81%) of 75 paediatric and young adult patients with relapsed or refractory B-cell acute lymphoblastic leukaemia achieved overall remission after treatment with tisagenlecleucel, a chimeric antigen receptor targeted against the CD19 antigen. We aimed to evaluate patient-reported quality of life in these patients before and after tisagenlecleucel infusion.

METHODS

ELIANA, a global, single-arm, open-label, phase 2 trial, was done in 25 hospitals across Australia, Austria, Belgium, Canada, France, Germany, Italy, Japan, Norway, Spain, and the USA. Patients with B-cell acute lymphoblastic leukaemia aged at least 3 years at the time of screening and 21 years or younger at the time of initial diagnosis who were in second or greater bone marrow relapse, chemorefractory, relapsed after allogeneic stem-cell transplantation, or were otherwise ineligible for allogeneic stem-cell transplantation were enrolled. Patients received a single intravenous administration of a target dose of 0·2-5 × 10⁶ transduced viable T cells per kg for patients weighing 50 kg or less or 0·1-2·5 × 10⁸ transduced viable T cells for patients weighing more than 50 kg. The primary outcome, reported previously, was the proportion of patients who achieved remission. A prespecified secondary endpoint, reported here, was patient-reported quality of life measured with the Pediatric Quality of Life Inventory (PedsQL) and European Quality of Life-5 Dimensions questionnaire (EQ-5D). Patients completed the questionnaires at baseline, day 28, and months 3, 6, 9, and 12 after treatment. The data collected were summarised using descriptive statistics and post-hoc mixed models for repeated measures. Change from baseline response profiles were illustrated with cumulative distribution function plots. The proportion of patients achieving the minimal clinically important difference and normative mean value were reported. Analysis was per protocol. This study is registered with ClinicalTrials.gov, NCT02435849.

FINDINGS

Between April 8, 2015, and April 25, 2017, 107 patients were screened, 92 were enrolled, and 75 received tisagenlecleucel. 58 patients aged 8-23 years were included in the analysis of quality of life. At baseline, 50 (86%) patients had completed the PedsQL questionnaire and 48 (83%) had completed the EQ-5D VAS. Improvements in patient-reported quality-of-life scores were observed for all measures at month 3 after tisagenlecleucel infusion (mean change from baseline to month 3 was 13·3 [95% CI 8·9-17·6] for the PedsQL total score and 16·8 [9·4-24·3] for the EQ-5D visual analogue scale). 30 (81%) of 37 patients achieved the minimal clinically important difference at month 3 for the PedsQL total score and 24 (67%) of 36 patients achieved this for the EQ-5D visual analogue scale.

INTERPRETATION

These findings, along with the activity and safety results of ELIANA, suggest a favourable benefit-risk profile of tisagenlecleucel in the treatment of paediatric and young adult patients with relapsed or refractory B-cell acute lymphoblastic leukaemia.

FUNDING

Novartis.

Long-term outcome of a randomized controlled study in patients with newly diagnosed severe aplastic anemia treated with antithymocyte globulin and cyclosporine, with or without granulocyte colony-stimulating factor: a Severe Aplastic Anemia Working Party Trial from the European Group of Blood and Marrow Transplantation

This follow-up study of a randomized, prospective trial included 192 patients with newly diagnosed severe aplastic anemia receiving antithymoglobulin and cyclosporine, with or without granulocyte colony-stimulating factor (G-CSF). We aimed to evaluate the long-term effect of G-CSF on overall survival, event-free survival, probability of secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML), clinical paroxysmal nocturnal hemoglobinuria, relapse, avascular osteonecrosis and chronic kidney disease. The median follow-up was 11.7 years (95% CI, 10.9-12.5). The overall survival rate at 15 years was 57±12% in the group given G-CSF and 63±12% in the group not given G-CSF (P=0.92); the corresponding event-free survival rates were 24±10% and 23±10%, respectively (P=0.36). In total, 9 patients developed MDS or AML, 10 only a clonal cytogenetic abnormality, 7 a solid cancer, 18 clinical paroxysmal nocturnal hemoglobinuria, 8 osteonecrosis, and 12 chronic kidney disease, without any difference between patients treated with or without G-CSF. The cumulative incidence of MDS, AML or isolated cytogenetic abnormality at 15 years was 8.5±3% for the G-CSF group and 8.2±3% for the non-G-CSF group (P=0.90). The cumulative incidence of any late event including myelodysplastic syndrome or acute myeloid leukemia, isolated cytogenetic abnormalities, solid cancer, clinical paroxysmal nocturnal hemoglobinuria, aseptic osteonecrosis, chronic kidney disease and relapse was 50±12% for the G-CSF group and 49±12% for the non-G-CSF group (P=0.65). Our results demonstrate that it is unlikely that G-CSF has an impact on the outcome of severe aplastic anemia; nevertheless, very late events are common and eventually affect the prognosis of these patients, irrespectively of their age at the time of immunosuppressive therapy (NCT01163942).

Death after hematopoietic stem cell transplantation: changes over calendar year time, infections and associated factors

Information on incidence, and factors associated with mortality is a prerequisite to improve outcome after hematopoietic stem cell transplantation (HSCT). Therefore, 55'668 deaths in 114'491 patients with HSCT (83.7% allogeneic) for leukemia were investigated in a landmark analysis for causes of death at day 30 (very early), day 100 (early), at 1 year (intermediate) and at 5 years (late). Mortality from all causes decreased from cohort 1 (1980-2001) to cohort 2 (2002-2015) in all post-transplant phases after autologous HSCT. After allogeneic HSCT, mortality from infections, GVHD, and toxicity decreased up to 1 year, increased at 5 years; deaths from relapse increased in all post-transplant phases. Infections of unknown origin were the main cause of infectious deaths. Lethal bacterial and fungal infections decreased from cohort 1 to cohort 2, not unknown or mixed infections. Infectious deaths were associated with patient-, disease-, donor type, stem cell source, center, and country- related factors. Their impact varied over the post-transplant phases. Transplant centres have successfully managed to reduce death after HSCT in the early and intermediate post-transplant phases, and have identified risk factors. Late post-transplant care could be improved by focus on groups at risk and better identification of infections of "unknown origin".

Allogeneic hematopoietic stem cell transplantation from unrelated donors is associated with higher infection rates in children with acute lymphoblastic leukemia-A prospective international multicenter trial on behalf of the BFM-SG and the EBMT-PDWP

Severe infections (SI) significantly impact on non‐relapse mortality after hematopoietic stem cell transplantation (HSCT). We assessed 432 children and adolescents with acute lymphoblastic leukemia (ALL) after total body irradiation based myeloablative HSCT within the multicenter ALL‐BFM‐SCT 2003 trial for SI grade 3 or higher according to common terminology criteria for adverse events. A total 172 patients experienced at least one SI. Transplantation from matched unrelated donors (MUD) was associated with any type of SI in the pre‐engraftment period (hazard ratio [HR]: 2.57; P < .001), and with any SI between day +30 and + 100 (HR: 2.91; P = .011). Bacterial (HR: 2.24; P = .041) and fungal infections (HR: 4.06; P = .057) occurred more often in the pre‐engraftment phase and viral infections more often before day +30 (HR: 2.66; P = .007) or between day +30 and + 100 (HR: 3.89; P = .002) after HSCT from MUD as compared to matched sibling donors. Chronic GvHD was an independent risk factor for any type of SI after day +100 (HR: 2.57; P < .002). We conclude that allogeneic HSCT from MUD in children and adolescents with pediatric ALL is associated with higher infection rates, which seems attributable to an intensified GvHD prophylaxis including serotherapy and methotrexate.

Prognostic impact of EBV serostatus in patients with lymphomas or chronic malignancies undergoing allogeneic HCT

The influence of the donor (D) and recipient (R) pre-transplant Epstein-Barr Virus (EBV) serostatus on transplant outcomes (overall survival, relapse-free survival, relapse incidence, non-relapse mortality, acute and chronic GVHD) in 12,931 patients with lymphomas or chronic malignancies undergoing allogeneic hematopoietic cell transplant (allo-HCT) between 1997-2016 was analyzed. In multivariate analysis, the risk of development of chronic GVHD was increased for EBV R+/D+ (HR = 1.26; p = 0.003), R+/D- (HR = 1.21; p = 0.044), and R-/D + (HR = 1.21; p = 0.048) in comparison to R-/D- transplants. No significance was shown for other transplant outcomes; however, in univariate analysis, EBV-seropositive patients receiving grafts from EBV-seropositive donors (EBV R+/D+transplants) had inferior transplant outcomes in comparison to EBV-seronegative recipients of grafts from EBV-seronegative donors (EBV R-/D-): inferior overall survival (59.6% vs 65.9%), inferior relapse-free survival (51.1% vs 57.5%), increased incidence of chronic GVHD (49.5% vs 41.8%), and increased incidence of de novo chronic GVHD (30.5% vs 24.0%). In conclusion, an EBV-negative recipient with lymphoma or chronic malignancy can benefit from selection of an EBV-negative donor in context of chronic GVHD, while there are no preferences in donor EBV serostatus for EBV-seropositive recipient.

The German National Registry of Primary Immunodeficiencies (2012-2017)

Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE- syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.

Allogeneic HSCT for Autoimmune Diseases: A Retrospective Study From the EBMT ADWP, IEWP, and PDWP Working Parties

Background: This retrospective study assessed the use and long-term outcome of allogeneic hematopoietic stem cell transplantation (HSCT) in patients with severe autoimmune diseases (ADs), reported to the European Society for Blood and Marrow Transplantation (EBMT) registry.

Methods: Between 1997 and 2014, 128 patients received allogeneic HSCT for various hematological (n = 49) and non-hematological (n = 79) refractory ADs. The median age was 12.7 years (0.2–62.2). Donors were syngeneic for seven, matched related for 46, unrelated for 51, haploidentical for 15, and cord blood for nine patients.

Results: The incidence of grades II-IV acute graft-vs.-host disease (GvHD) was 20.8% at 100 days. Cumulative incidence of chronic GvHD was 27.8% at 5-years. Non-relapse mortality (NRM) was 12.7% at 100-days. Overall survival (OS) and Progression-Free Survival (PFS) were 70.2 and 59.4% at 5-years, respectively. By multivariate analysis, age <18 years, males, and more recent year of transplant were found to be significantly associated with improved PFS. Reduced conditioning intensity was associated with a lower NRM. On a subgroup of 64 patients with detailed information a complete clinical response was obtained in 67% of patients at 1-year.

Conclusions: This large EBMT survey suggests the potential of allogeneic HSCT to induce long-term disease control in a large proportion of refractory ADs, with acceptable toxicities and NRM, especially in younger patients.

Abstract CT077: Potential utility of minimal residual disease (MRD) to identify relapse in pediatric and young adult (AYA) B-cell acute lymphoblastic leukemia (B-ALL) patients treated with tisagenlecleucel

Background: Detection of MRD is an important predictor of patient outcome following treatment of B-ALL; importantly, MRD is emerging as a useful tool to detect early relapse, which may fulfill a key previously unmet clinical need. Objective: To evaluate the potential of MRD to predict morphologic relapse in pediatric and AYA patients with B-ALL.

Methods: Bone marrow (BM) and peripheral blood (PB) specimens at screening (pre-tisagenlecleucel infusion), post-infusion, and relapse from two B-ALL clinical trials (ELIANA [NCT02435849] and ENSIGN [NCT02228096]) were tested using immunoglobulin next-generation sequencing (IgNGS) and flow cytometry (FC). We assessed concordance between two MRD assays to determine which method could support early relapse detection and whether using PB with IgNGS was comparable with BM testing with FC.

Results: IgNGS was performed in 300 samples from 88 patients. 237 samples from 83 patients also had FC MRD results available. Baseline samples, which had high disease burden, showed 100% MRD concordance between both assays. However, post-treatment, where the leukemic burden was dramatically reduced, IgNGS detected a greater number of MRD-positive samples vs FC at each sensitivity level tested (10-4, 10-5, and 10-6). At the highest sensitivity level of 10-6, IgNGS was able to detect 18% more MRD-positive post-treatment samples. IgNGS was able to detect MRD positivity 1-4 months ahead of clinical relapse in a small number of relapsed patients, whether relapse was CD19+ or CD19-. MRD burden in BM was higher than in PB using both FC and IgNGS. In patients with matching data available, IgNGS was able to detect more MRD-positive PB samples than FC MRD-positive BM samples. Patients who were MRD negative by both IgNGS and FC at the end of first month post-infusion had better progression-free survival (PFS) and overall survival (OS) compared with those with detectable MRD. Tumor clonality at baseline and clonal evolution following tisagenlecleucel treatment will be presented.

Conclusion: MRD detection using IgNGS in PB may be used as a surrogate for FC assessment of MRD in BM. Patients who were MRD negative by IgNGS 1 month after infusion had improved PFS and OS vs those with detectable MRD; ongoing studies will provide further information on the applicability of IgNGS MRD detection and its association with long-term outcome in tisagenlecleucel-treated pediatric and AYA relapsed/refractory B-ALL patients.

Citation Format: Michael A. Pulsipher, Xia Han, Máire Quigley, Gabor Kari, Susana Rives, Theodore W. Laetsch, Gary D. Myers, Hidefumi Hiramatsu, Gregory A. Yanik, Muna Qayed, Timothy Driscoll, Michael W. Boyer, Heather Stefanski, Jochen Buchner, Andre Baruchel, Peter Bader, Lan Yi, Creton Kalfoglou, Harlan Robins, Erik Yusko, Gullu Gorgun, Eric Bleickardt, Stephane Wong, Stephan A. Grupp. Potential utility of minimal residual disease (MRD) to identify relapse in pediatric and young adult (AYA) B-cell acute lymphoblastic leukemia (B-ALL) patients treated with tisagenlecleucel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT077.

Solid organ transplantation after hematopoietic stem cell transplantation in childhood: A multicentric retrospective survey

We report data obtained from a retrospective multicenter pediatric survey on behalf of the European Society for Blood and Marrow Transplantation (EBMT). Information on solid organ transplantation (SOT) performed in pediatric recipients of either autologous or allogeneic hematopoietic stem cell transplantation (HSCT) between 1984 and 2016 was collected in 20 pediatric EBMT Centers (25.6%). Overall, we evaluated data on 44 SOTs following HSCT including 20 liver (LTx), 12 lung (LuTx), 6 heart (HTx), and 6 kidney (KTx) transplantations. The indication for SOT was organ failure related to intractable graft-vs-host disease in 16 children (36.3%), acute or chronic HSCT-related toxicity in 18 (40.9%), and organ dysfunction related to the underlying disease in 10 (22.8%). The median follow-up was 10.9 years (95% confidence interval: 1.7-29.5). The overall survival rate at 1 and 5 years after SOT was 85.7% and 80.4%, respectively: it was 74% and 63.2% after LTx, 83.2% after HTx, and 100% equally after LuTx and KTx. This multicenter survey confirms that SOT represents a promising option in children with severe organ failure occurring after HSCT. Additional studies are needed to further establish the effectiveness of SOT after HSCT and to better understand the mechanism underlying this encouraging success.

Improving Clinical Manufacturing of IL-15 Activated Cytokine-Induced Killer (CIK) Cells

Cytokine-induced killer (CIK) cells are an immunotherapeutic approach to combat relapse following allogeneic hematopoietic stem cell transplantation (HSCT) in acute leukemia or myelodysplastic syndrome (MDS) patients. Prompt and sequential administration of escalating cell doses improves the efficacy of CIK cell therapy without exacerbating graft vs. host disease (GVHD). This study addresses manufacturing-related issues and aimed to develop a time-, personal- and cost-saving good manufacturing process (GMP)-compliant protocol for the generation of ready-for-use therapeutic CIK cell doses starting from one unstimulated donor-derived peripheral blood (PB) or leukocytapheresis (LP) products. Culture medium with or without the addition of either AB serum, fresh frozen plasma (FFP) or platelet lysate (PL) was used for culture. Fresh and cryopreserved CIK cells were compared regarding expansion rate, viability, phenotype, and ability to inhibit leukemia growth. Cell numbers increased by a median factor of 10-fold in the presence of FFP, PL, or AB serum, whereas cultivation in FFP/PL-free or AB serum-free medium failed to promote adequate CIK cell proliferation (p < 0.01) needed to provide clinical doses of 1 × 10⁶ T cells/kG, 5 × 10⁶ T cells/kG, 1 × 10⁷ T cells/kG, and 1 × 10⁸ T cells/kG recipient body weight. CIK cells consisting of T cells, T- natural killer (T-NK) cells and a minor fraction of NK cells were not significantly modified by different medium supplements. Moreover, neither cytotoxic potential against leukemic THP-1 cells nor cell activation shown by CD25 expression were significantly influenced. Moreover, overnight and long-term cryopreservation had no significant effect on the composition of CIK cells, their phenotype or cytotoxic potential. A viability of almost 93% (range: 89–96) and 89.3% (range: 84–94) was obtained after freeze-thawing procedure and long-term storage, respectively, whereas viability was 96% (range: 90-97) in fresh CIK cells. Altogether, GMP-complaint CIK cell generation from an unstimulated donor-derived PB or LP products was feasible. Introducing FFP, which is easily accessible, into CIK cell cultures was time- and cost-saving without loss of viability and potency in a 10-12 day batch culture. The feasibility of cryopreservation enabled storage and delivery of sequential highly effective ready-for-use CIK cell doses and therefore reduced the number of manufacturing cycles.

Gonadal Function after Busulfan Compared with Treosulfan in Children and Adolescents Undergoing Allogeneic Hematopoietic Stem Cell Transplant

Gonadal impairment is an important late effect with a significant impact on quality of life of transplanted patients. The aim of this study was to compare gonadal function after busulfan (Bu) or treosulfan (Treo) conditioning regimens in pre- and postpubertal children. This retrospective, multicenter study included children transplanted in pediatric European Society for Blood and Marrow Transplantation (EBMT) centers between 1992 and 2012 who did not receive gonadotoxic chemoradiotherapy before the transplant. We evaluated 137 patients transplanted in 25 pediatric EBMT centers. Median age at transplant was 11.04 years (range, 5 to 18); 89 patients were boys and 48 girls. Eighty-nine patients were prepubertal at transplant and 48 postpubertal. One hundred eighteen children received Bu and 19 Treo. A higher proportion of girls treated with Treo in the prepubertal stage reached spontaneous puberty compared with those treated with Bu (P = .02). Spontaneous menarche was more frequent after Treo than after Bu (P < .001). Postpubertal boys and girls treated with Treo had significantly lower luteinizing hormone levels (P = .03 and P = .04, respectively) compared with the Bu group. Frequency of gonadal damage associated with Treo was significantly lower than that observed after Bu. These results need to be confirmed in a larger population.

Transplant center practices for psychosocial assessment and management of pediatric hematopoietic stem cell donors

Understanding the potential emotional and psychological risks of pediatric sibling HSC donation is an area of research that remains in its infancy. A cross-sectional survey was distributed electronically to directors at all CIBMTR and EBMT centers to describe current transplant center practices for obtaining assent, preparation for the physical/emotional experiences of donation, and monitoring the post-donation well-being of pediatric donors (<18 years of age). Respondents were 45/91 (49%) and 66/144 (46%) of CIBMTR and EBMT centers, respectively. Although 78% of centers reported having a mechanism in place to ensure donor free assent, centers also reported only limited assessment of psychosocial suitability to manage the emotional risks of donation. More than half of centers reported no psychosocial follow-up assessment post-donation. Few centers have policies in place to address donor psychological needs. Future investigations should include medical and psychosocial outcomes following full integration of comprehensive psychosocial screening and surveillance of pediatric donors.

Indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders: current practice in Europe, 2019

This is the seventh special EBMT report on the indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders. Our aim is to provide general guidance on transplant indications according to prevailing clinical practice in EBMT countries and centres. In order to inform patient decisions, these recommendations must be considered together with the risk of the disease, the risk of the transplant procedure and the results of non-transplant strategies. In over two decades since the first report, the EBMT indications manuscripts have incorporated changes in transplant practice coming from scientific and technical developments in the field. In this same period, the establishment of JACIE accreditation has promoted high quality and led to improved outcomes of patient and donor care and laboratory performance in transplantation and cellular therapy. An updated report with operating definitions, revised indications and an additional set of data with overall survival at 1 year and non-relapse mortality at day 100 after transplant in the commonest standard-of-care indications is presented. Additional efforts are currently underway to enable EBMT member centres to benchmark their risk-adapted outcomes as part of the Registry upgrade Project 2020 against national and/or international outcome data.

Genetically engineered CAR NK cells display selective cytotoxicity against FLT3-positive B-ALL and inhibit in vivo leukemia growth

Chimeric antigen receptor (CAR)-engineered natural killer (NK) cells represent a promising effector cell type for adoptive cancer immunotherapy. Both, genetically modified donor-derived NK cells as well as continuously expanding NK-92 cells are currently under clinical development. To enhance their therapeutic utility for the treatment of pre-B-cell acute lymphoblastic leukemia (B-ALL), we engineered NK-92 cells by lentiviral gene transfer to express a FMS-like tyrosine kinase 3 (FLT3)-specific CAR that contains a composite CD28-CD3ζ signaling domain. FLT3 has primarily been described as a therapeutic target for acute myeloid leukemia, but overexpression of FLT3 has also been reported in B-ALL. Exposure of FLT3-positive targets to CAR NK-92 cells resulted in conjugate formation between NK and leukemia cells, NK-cell degranulation and selective cytotoxicity toward established B-ALL cell lines and primary blasts that were resistant to parental NK-92. In a SEM B-ALL xenograft model in NOD-SCID IL2R γ^null mice, treatment with CAR NK-92 but not parental NK-92 cells markedly inhibited disease progression, demonstrating high antileukemic activity in vivo. As FLT3 is known to be also expressed on precursor cells, we assessed the feasibility of incorporating an inducible caspase-9 (iCasp9) suicide switch to enhance safety of our approach. Upon addition of the chemical dimerizer AP20187 to NK-92 cells coexpressing the FLT3-specific CAR and iCasp9, rapid iCasp9 activation was observed, precluding further CAR-mediated cytotoxicity. Our data demonstrate that B-ALL can be effectively targeted by FLT3-specific CAR NK cells which may complement CD19-directed immunotherapies, particularly in cases of inherent or acquired resistance to the latter.

Clearance of Hematologic Malignancies by Allogeneic Cytokine-Induced Killer Cell or Donor Lymphocyte Infusions

Well-established donor lymphocyte infusion (DLI) and novel cytokine-induced killer (CIK) cell therapy for the treatment of relapsing hematologic malignancies after allogeneic hematopoietic stem cell transplantation (HSCT) were compared with respect to feasibility, safety, and efficacy. Altogether, a total of 221 infusions were given to 91 patients (DLI, n = 55; CIK, n = 36). T cell recovery was significantly improved after CIK cell therapy (P < .0001). Although patients with CIK cell treatment showed a significantly worse prognosis at the time of HSCT (risk score, 1.7 versus 2.1; P < .0001), DLI and CIK cell therapy induced complete remission (CR) in 29% and 53% patients, respectively, whereas relapse occurred in 71% and 47%. In both groups, all patients with overt hematologic relapse at the time of immunotherapy (DLI, n = 11; CIK, n = 8) succumbed to their disease, while 36% and 68% patients with DLI or CIK cell therapy applied due to molecular relapse or active disease at the time of transplantation achieved CR. The 6-month overall survival rate in the latter patients was 57% and 77%, respectively, with a median follow-up of 27.9 months (range, .9 to 149.2 months). The 6-month cumulative incidence of relapse was 55% and 22% in patients who received DLI and CIK cell therapy, respectively (P = .012). Acute graft-versus-host disease developed in 35% of the patients who received DLI and in 25% of those who received CIK. No transfusion-related deaths occurred. These data, while underscoring the therapeutic value of conventional DLI, suggest the improved safety and to a certain extent efficacy of CIK cell therapy for patients at high risk for post-transplantation relapse of various hematologic malignancies.