Virus-reactive T cells expanded in aplastic anemia eliminate hematopoietic progenitor cells by molecular mimicry.

ABSTRACT: Acquired aplastic anemia is a bone marrow failure syndrome characterized by hypocellular bone marrow and peripheral blood pancytopenia. Frequent clinical responses to calcineurin inhibition and antithymocyte globulin strongly suggest critical roles for hematopoietic stem/progenitor cell-reactive T-cell clones in disease pathophysiology; however, their exact contribution and antigen specificities remain unclear. We determined differentiation states and targets of dominant T-cell clones along with their potential to eliminate hematopoietic progenitor cells in the bone marrow of 15 patients with acquired aplastic anemia. Single-cell sequencing and immunophenotyping revealed oligoclonal expansion and effector differentiation of CD8+ T-cell compartments. We reexpressed 28 dominant T-cell receptors (TCRs) of 9 patients in reporter cell lines to determine reactivity with (1) in vitro-expanded CD34+ bone marrow, (2) CD34- bone marrow, or (3) peptide pools covering immunodominant epitopes of highly prevalent viruses. Besides 5 cytomegalovirus-reactive TCRs, we identified 3 TCRs that recognized antigen presented on hematopoietic progenitor cells. T cells transduced with these TCRs eliminated hematopoietic progenitor cells of the respective patients in vitro. One progenitor cell-reactive TCR (11A5) also recognized an epitope of the Epstein-Barr virus-derived latent membrane protein 1 (LMP1) presented on HLA-A∗02:01. We identified 2 LMP1-related mimotopes within the human proteome as activating targets of TCR 11A5, providing proof of concept that molecular mimicry of viral and self-epitopes can drive T cell-mediated elimination of hematopoietic progenitor cells in aplastic anemia.

Soluble lymphocyte activation gene-3 (sLAG3) and CD4/CD8 ratio dynamics as predictive biomarkers in patients undergoing immune checkpoint blockade for solid malignancies.

BACKGROUND: The search for biomarkers to identify suitable candidates for immune checkpoint inhibitor (ICI) therapy remains ongoing. We evaluate how soluble levels of the next generation immune checkpoint Lymphocyte Activation Gene-3 (sLAG-3) and its association with circulating T lymphocyte subsets could pose as a novel biomarker to predict outcome to ICI therapy. METHODS: Circulating levels of sLAG3 were analyzed using multiplex immunoassay in n = 84 patients undergoing ICI therapy for advanced solid cancer, accompanied by flow cytometry analyses of peripheral blood mononuclear cells (PBMCs). RESULTS: Uni- and multivariate analysis shows that patients with higher sLAG3 concentrations before ICI therapy had a significantly impaired progression-free (PFS) and overall survival (OS) (HRPFS: 1.005 [95%CI: 1.000-1.009], p = 0.039; HROS: 1.006 [95%CI: 1.001-1.011], p = 0.015). The CD4/CD8 cell ratio and its dynamics during therapy were strong predictors of PFS and OS with patients with a decreasing ratio between baseline and after 1-2 cycles having an improved median OS compared to patients with increasing values (p = 0.012, HR: 3.32). An immunological score combining sLAG3 and the CD4/CD8 ratio showed the highest predictive potential (HROS: 10.3). CONCLUSION: Pending prospective validation, sLAG3 and correlating circulating T-cell subsets can be used as a non-invasive predictive marker to predict outcome to ICI therapy to help identifying ideal ICI candidates in the future.

CEBPA mutations in 4708 patients with acute myeloid leukemia: differential impact of bZIP and TAD mutations on outcome.

Biallelic mutations of the CEBPA gene (CEBPAbi) define a distinct entity associated with favorable prognosis; however, the role of monoallelic mutations (CEBPAsm) is poorly understood. We retrospectively analyzed 4708 adults with acute myeloid leukemia (AML) who had been recruited into the Study Alliance Leukemia trials, to investigate the prognostic impact of CEBPAsm. CEBPA mutations were identified in 240 patients (5.1%): 131 CEBPAbi and 109 CEBPAsm (60 affecting the N-terminal transactivation domains [CEBPAsmTAD] and 49 the C-terminal DNA-binding or basic leucine zipper region [CEBPAsmbZIP]). Interestingly, patients carrying CEBPAbi or CEBPAsmbZIP shared several clinical factors: they were significantly younger (median, 46 and 50 years, respectively) and had higher white blood cell (WBC) counts at diagnosis (median, 23.7 × 109/L and 35.7 × 109/L) than patients with CEBPAsmTAD (median age, 63 years, median WBC 13.1 × 109/L; P < .001). Co-mutations were similar in both groups: GATA2 mutations (35.1% CEBPAbi; 36.7% CEBPAsmbZIP vs 6.7% CEBPAsmTAD; P < .001) or NPM1 mutations (3.1% CEBPAbi; 8.2% CEBPAsmbZIP vs 38.3% CEBPAsmTAD; P < .001). CEBPAbi and CEBPAsmbZIP, but not CEBPAsmTAD were associated with significantly improved overall (OS; median 103 and 63 vs 13 months) and event-free survival (EFS; median, 20.7 and 17.1 months vs 5.7 months), in univariate and multivariable analyses. Additional analyses revealed that the clinical and molecular features as well as the favorable survival were confined to patients with in-frame mutations in bZIP (CEBPAbZIP-inf). When patients were classified according to CEBPAbZIP-inf and CEBPAother (including CEBPAsmTAD and non-CEBPAbZIP-inf), only patients bearing CEBPAbZIP-inf showed superior complete remission rates and the longest median OS and EFS, arguing for a previously undefined prognostic role of this type of mutation.

Time from diagnosis to treatment has no impact on survival in newly diagnosed acute myeloid leukemia treated with venetoclax-based regimens.

In newly diagnosed acute myeloid leukemia (AML), immediate initiation of treatment is standard of care. However, deferral of antileukemic therapy may be indicated to assess comorbidities or pretherapeutic risk factors. We explored the impact of time from diagnosis to treatment on outcomes in newly diagnosed AML undergoing venetoclax-based therapy in two distinct cohorts. By querying the Study Alliance Leukemia database and the global health network TriNetX, we identified 138 and 717 patients respectively with an average age of 76 and 72 years who received venetoclax-based first-line therapy. When comparing patients who started treatment earlier or later than 10 days after initial diagnosis, no significant difference in median overall survival was observed - neither in the SAL cohort (7.7 vs. 9.6 months; P=0.42) nor in the TriNetX cohort (7.5 vs. 7.2 months; P=0.41). Similarly, severe infections, bleeding, and thromboembolic events were equally observed between early and later treatments, both in the overall patient groups and specific subgroups (age ≥75 years or leukocytes ≥20x109/L). This retrospective analysis indicates that delaying the start of venetoclax-based therapy in newly diagnosed AML might be a safe option for selected patients, provided that close clinical monitoring is performed.

Practical considerations in the management of patients treated with bosutinib for chronic myeloid leukemia.

Bosutinib is a second-generation tyrosine kinase inhibitor indicated for the treatment of patients with newly diagnosed Philadelphia chromosome-positive chronic phase chronic myeloid leukemia (CML), and for patients with Ph + chronic phase, accelerated phase, or blast phase CML resistant or intolerant to prior therapy. As is the case for all TKIs approved for treatment of CML, bosutinib is associated with adverse events (AEs) that require appropriate management to ensure adherence to treatment and optimized outcomes. The aim of this review is to provide physicians with updated practical information for the prevention and management of AEs occurring during treatment with bosutinib, including dosing strategies, based on the latest published evidence and clinical experience. Clinical studies and real-world evidence have shown bosutinib has a generally favorable safety profile, which has remained consistent across lines of therapy and in long-term reports. Adjusting the starting dose and/or modifying the dose during treatment with bosutinib are important strategies to manage AEs and improve tolerability, which are recognized within the label and in treatment guidelines. Dosing adjustment strategies to manage AEs are a recognized management approach for other TKIs in the treatment of CML and are not exclusive to bosutinib. In summary, long-term results from clinical trials and emerging real-world evidence demonstrate bosutinib has a safety profile that can largely be managed with treatment modifications and/or supportive care. Increased experience in managing toxicities and by using a personalized dosing approach may further improve adherence and outcomes with bosutinib.

Bone marrow biopsy in geriatric patients above the age of 85 years: invaluable or unnecessary? A retrospective analysis.

Bone marrow biopsy (BMB) is a well-established diagnostic tool for various hematological, oncological, and other medical conditions. However, treatment options for geriatric patients (pts) facing these diseases are often constrained. In this single-center, retrospective analysis we assessed the diagnostic value of BMB in geriatric pts aged ≥ 85 years and examined its impact on therapeutic decisions. We examined 156 BMB procedures in 129 pts, extracting data from the electronic patient records and applying descriptive statistical methods. Nearly half of the primary diagnostic procedures (26; 44.1%) resulted in a modification of the initially suspected diagnosis. Notably, 15 (25.4%) of these procedures, led to changes in both the diagnosis and planned interventional treatment. Among the 15 follow-up procedures (36.6%), disease progression was initially suspected based on symptoms, but BMB results excluded such progression. In lymphoma staging biopsies, only 2 (3.6%) prompted a change in therapeutic intervention. Importantly, no BMB-related complications, such as bleeding, infection or nerve damage, were reported. Median survival after BMB was 16.1 months across all pts, yet it varied based on the diagnosis and comorbidity score. The survival of pts with a change in therapy based on BMB results did not significantly differ from those who did not undergo a therapy change. In conclusion, BMB proved to be generally safe and beneficial in this geriatric cancer patient cohort beyond the age of 85 years. However, the advantages of lymphoma staging in this patient population warrant further consideration.

Activating mutations in JAK2 and CALR differentially affect intracellular calcium flux in store operated calcium entry.

BACKGROUND: Calcium (Ca2+) signaling regulates various vital cellular functions, including integrin activation and cell migration. Store-operated calcium entry (SOCE) via calcium release-activated calcium (CRAC) channels represents a major pathway for Ca2+ influx from the extracellular space in multiple cell types. The impact of JAK2-V617F and CALR mutations which are disease initiating in myeloproliferative neoplasms (MPN) on SOCE, calcium flux from the endoplasmic reticulum (ER) to the cytosol, and related key signaling pathways in the presence or absence of erythropoietin (EPO) or thrombopoietin (TPO) is poorly understood. Thus, this study aimed to elucidate the effects of these mutations on the aforementioned calcium dynamics, in cellular models of MPN. METHODS: Intracellular Ca2+ levels were measured over a time frame of 0-1080 s in Fura-2 AM labeled myeloid progenitor 32D cells expressing various mutations (JAK2-WT/EpoR, JAK2-V617F/EpoR; CALR-WT/MPL, CALR-ins5/MPL, and del52/MPL). Basal Ca2+ concentrations were assessed from 0-108 s. Subsequently, cells were stimulated with EPO/TPO in Ca2+-free Ringer solution, measuring Ca2+ levels from 109-594 s (store depletion). Then, 2 mM of Ca2+ buffer resembling physiological concentrations was added to induce SOCE, and Ca2+ levels were measured from 595-1080 s. Fura-2 AM emission ratios (F340/380) were used to quantify the integrated Ca2+ signal. Statistical significance was assessed by unpaired Student's t-test or Mann-Whitney-U-test, one-way or two-way ANOVA followed by Tukey's multiple comparison test. RESULTS: Following EPO stimulation, the area under the curve (AUC) representing SOCE significantly increased in 32D-JAK2-V617F cells compared to JAK2-WT cells. In TPO-stimulated CALR cells, we observed elevated Ca2+ levels during store depletion and SOCE in CALR-WT cells compared to CALR-ins5 and del52 cells. Notably, upon stimulation, key components of the Ca2+ signaling pathways, including PLCγ-1 and IP3R, were differentially affected in these cell lines. Hyper-activated PLCγ-1 and IP3R were observed in JAK2-V617F but not in CALR mutated cells. Inhibition of calcium regulatory mechanisms suppressed cellular growth and induced apoptosis in JAK2-V617F cells. CONCLUSIONS: This report highlights the impact of JAK2 and CALR mutations on Ca2+ flux (store depletion and SOCE) in response to stimulation with EPO and TPO. The study shows that the JAK2-V617F mutation strongly alters the regulatory mechanism of EpoR/JAK2-dependent intracellular calcium balance, affecting baseline calcium levels, EPO-induced calcium entry, and PLCγ-1 signaling pathways. Our results reveal an important role of calcium flux in the homeostasis of JAK2-V617F positive cells.

Retrospective study on pomalidomide-PACE as a salvage regimen in aggressive relapsed and refractory multiple myeloma.

OBJECTIVES: Despite major advances in treatment options for multiple myeloma (MM), patients refractory to the main drug classes and those with aggressive, especially extramedullary disease, still face a dismal outcome. For these patients, effective therapeutic options are urgently warranted. METHODS: In this retrospective study, we report on the safety and efficacy of the intensive combination regimen of pomalidomide plus cisplatin, doxorubicin, cyclophosphamide, and etoposide (Pom-PACE) in patients with relapsed refractory MM (RRMM) or plasma cell leukemia (PCL). A study population of 20 consecutive patients treated with Pom-PACE at two academic centers was included for analysis. All patients had to have a confirmed relapse according to International Myeloma Working Group criteria and adequate organ function prior to the start of therapy. Data were collected by reviewing medical charts. Exploratory analyses were performed with regard to efficacy and safety. RESULTS: Patients were heavily pretreated with a median number of four prior therapies (range: 1-10). All patients were exposed to immunomodulators, proteasome inhibitors, and alkylating agents, 80% were double-class refractory, 40% were triple-class refractory. Extramedullary MM or PCL were present in 15 patients (75%). Overall response rate (ORR) was 68%, with 31% achieving at least a very good partial response. Responses were achieved rapidly with an ORR of 64% after one cycle. Median progression-free survival was 8.9 months (0.92-not reached [NR]) and median overall survival was 11.8 months (3-40.6). Pom-PACE was associated with significant toxicity. All evaluable patients experienced Grade 4 hematological toxicity. However, no treatment related mortality was observed. CONCLUSION: Pomalidomide-PACE was able to induce rapid responses in heavily pretreated, aggressive RRMM with a manageable toxicity profile and therefore offers an effective salvage regimen and a potential bridging strategy to further treatment options such as chimeric antigen receptor T-cell therapy.

Combination of nivolumab with standard induction chemotherapy in children and adults with EBV-positive nasopharyngeal carcinoma : Protocol of a prospective multicenter phase 2 trial.

BACKGROUND: Treatment of Epstein-Barr virus(EBV)-positive nasopharyngeal carcinoma (NPC) with cisplatin/5-fluorouracil (5-FU) induction chemotherapy, followed by radiochemotherapy and subsequent interferon­ß, has yielded high survival rates in children, adolescents, and young adults. A previous study has shown that reduction of radiation dose from 59.4 to 54.0 Gy appears to be safe in patients with complete response (CR) to induction chemotherapy. As immune checkpoint-inhibitors have shown activity in NPC, we hypothesize that the addition of nivolumab to standard induction chemotherapy would increase the rate of complete tumor responses, thus allowing for a reduced radiation dose in a greater proportion of patients. METHODS: This is a prospective multicenter phase 2 clinical trial including pediatric and adult patients with their first diagnosis of EBV-positive NPC, scheduled to receive nivolumab in addition to standard induction chemotherapy. In cases of non-response to induction therapy (stable or progressive disease), and in patients with initial distant metastasis, treatment with nivolumab will be continued during radiochemotherapy. Primary endpoint is tumor response on magnetic resonance imaging (MRI) and positron emission tomography (PET) after three cycles of induction chemotherapy. Secondary endpoints are event-free (EFS) and overall survival (OS), safety, and correlation of tumor response with programmed cell death ligand 1 (PD-L1) expression. DISCUSSION: As cure rates in localized EBV-positive NPC today are high with standard multimodal treatment, the focus increasingly shifts toward prevention of late effects, the burden of which is exceptionally high, mainly due to intense radiotherapy. Furthermore, survival in patients with metastatic disease and resistant to conventional chemotherapy remains poor. Primary objective of this study is to investigate whether the addition of nivolumab to standard induction chemotherapy in children and adults with EBV-positive NPC is able to increase the rate of complete responses, thus enabling a reduction in radiation dose in more patients, but also offer patients with high risk of treatment failure the chance to benefit from the addition of nivolumab. TRIAL REGISTRATION: EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) No. 2021-006477-32.

XBP1 promotes NRASG12D pre-B acute lymphoblastic leukaemia through IL-7 receptor signalling and provides a therapeutic vulnerability for oncogenic RAS.

Activating point mutations of the RAS gene act as driver mutations for a subset of precursor-B cell acute lymphoblastic leukaemias (pre-B ALL) and represent an ambitious target for therapeutic approaches. The X box-binding protein 1 (XBP1), a key regulator of the unfolded protein response (UPR), is critical for pre-B ALL cell survival, and high expression of XBP1 confers poor prognosis in ALL patients. However, the mechanism of XBP1 activation has not yet been elucidated in RAS mutated pre-B ALL. Here, we demonstrate that XBP1 acts as a downstream linchpin of the IL-7 receptor signalling pathway and that pharmacological inhibition or genetic ablation of XBP1 selectively abrogates IL-7 receptor signalling via inhibition of its downstream effectors, JAK1 and STAT5. We show that XBP1 supports malignant cell growth of pre-B NRASG12D ALL cells and that genetic loss of XBP1 consequently leads to cell cycle arrest and apoptosis. Our findings reveal that active XBP1 prevents the cytotoxic effects of a dual PI3K/mTOR pathway inhibitor (BEZ235) in pre-B NRASG12D ALL cells. This implies targeting XBP1 in combination with BEZ235 as a promising new targeted strategy against the oncogenic RAS in NRASG12D -mutated pre-B ALL.

Telomere biology disorders may manifest as common variable immunodeficiency (CVID).

Telomere biology disorders (TBD) are caused by germline pathogenic variants in genes related to telomere maintenance and are characterized by critically short telomeres. In contrast to classical dyskeratosis congenita (DC), which is typically diagnosed in infancy, adult or late onset TBD frequently lack the typical DC triad and rather show variable organ manifestations and a cryptic disease course, thus complicating its diagnosis. Common variable immunodeficiency (CVID), on the other hand, is a primary antibody deficiency (PAD) syndrome. PADs are a heterogenous group of diseases characterized by hypogammaglobulinemia which occurs due to dysfunctional B lymphocytes and additional autoimmune and autoinflammatory complications. Genetic screening reveals a monogenic cause in a subset of CVID patients (15-35%). In our study, we screened the exomes of 491 CVID patients for the occurrence of TBD-related variants in 13 genes encoding for telomere/telomerase-associated proteins, which had previously been linked to the disease. We found 110/491 patients (22%) carrying 91 rare candidate variants in these 13 genes. Following the American College of Medical Genetics and Genomics (ACMG) guidelines, we classified two variants as benign, two as likely benign, 64 as variants of uncertain significance (VUS), four as likely pathogenic, and one heterozygous variant in an autosomal recessive disease gene as pathogenic. We performed telomere length measurement in 42 of the 110 patients with candidate variants and CVID. Two of these 42 patients showed significantly shorter telomeres compared to controls in both lymphocytes and granulocytes. Following the evaluation of the published literature and the patient's manifestations, we re-classified two VUS as likely pathogenic variants. Thus, 0.5-1% of all CVID patients in our study carry possibly pathogenic variants in telomere/telomerase-associated genes. Our data adds CVID to the broad clinical spectrum of cryptic adult-onset TBD. As the molecular diagnosis greatly impacts patient management and treatment strategies, we advise inclusion of all TBD-associated genes-despite their low prevalence-into the molecular screening of patients with antibody deficiencies.

JAK2-V617F and interferon-α induce megakaryocyte-biased stem cells characterized by decreased long-term functionality.

We studied a subset of hematopoietic stem cells (HSCs) that are defined by elevated expression of CD41 (CD41hi) and showed bias for differentiation toward megakaryocytes (Mks). Mouse models of myeloproliferative neoplasms (MPNs) expressing JAK2-V617F (VF) displayed increased frequencies and percentages of the CD41hi vs CD41lo HSCs compared with wild-type controls. An increase in CD41hi HSCs that correlated with JAK2-V617F mutant allele burden was also found in bone marrow from patients with MPN. CD41hi HSCs produced a higher number of Mk-colonies of HSCs in single-cell cultures in vitro, but showed reduced long-term reconstitution potential compared with CD41lo HSCs in competitive transplantations in vivo. RNA expression profiling showed an upregulated cell cycle, Myc, and oxidative phosphorylation gene signatures in CD41hi HSCs, whereas CD41lo HSCs showed higher gene expression of interferon and the JAK/STAT and TNFα/NFκB signaling pathways. Higher cell cycle activity and elevated levels of reactive oxygen species were confirmed in CD41hi HSCs by flow cytometry. Expression of Epcr, a marker for quiescent HSCs inversely correlated with expression of CD41 in mice, but did not show such reciprocal expression pattern in patients with MPN. Treatment with interferon-α further increased the frequency and percentage of CD41hi HSCs and reduced the number of JAK2-V617F+ HSCs in mice and patients with MPN. The shift toward the CD41hi subset of HSCs by interferon-α provides a possible mechanism of how interferon-α preferentially targets the JAK2 mutant clone.

Nintedanib targets KIT D816V neoplastic cells derived from induced pluripotent stem cells of systemic mastocytosis.

The KIT D816V mutation is found in >80% of patients with systemic mastocytosis (SM) and is key to neoplastic mast cell (MC) expansion and accumulation in affected organs. Therefore, KIT D816V represents a prime therapeutic target for SM. Here, we generated a panel of patient-specific KIT D816V induced pluripotent stem cells (iPSCs) from patients with aggressive SM and mast cell leukemia to develop a patient-specific SM disease model for mechanistic and drug-discovery studies. KIT D816V iPSCs differentiated into neoplastic hematopoietic progenitor cells and MCs with patient-specific phenotypic features, thereby reflecting the heterogeneity of the disease. CRISPR/Cas9n-engineered KIT D816V human embryonic stem cells (ESCs), when differentiated into hematopoietic cells, recapitulated the phenotype observed for KIT D816V iPSC hematopoiesis. KIT D816V causes constitutive activation of the KIT tyrosine kinase receptor, and we exploited our iPSCs and ESCs to investigate new tyrosine kinase inhibitors targeting KIT D816V. Our study identified nintedanib, a US Food and Drug Administration-approved angiokinase inhibitor that targets vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and fibroblast growth factor receptor, as a novel KIT D816V inhibitor. Nintedanib selectively reduced the viability of iPSC-derived KIT D816V hematopoietic progenitor cells and MCs in the nanomolar range. Nintedanib was also active on primary samples of KIT D816V SM patients. Molecular docking studies show that nintedanib binds to the adenosine triphosphate binding pocket of inactive KIT D816V. Our results suggest nintedanib as a new drug candidate for KIT D816V-targeted therapy of advanced SM.

Efficacy and safety of ruxolitinib in patients with newly-diagnosed polycythemia vera: futility analysis of the RuxoBEAT clinical trial of the GSG-MPN study group.

Patients (pts) with polycythemia vera (PV) suffer from pruritus, night sweats, and other symptoms, as well as from thromboembolic complications and progression to post-PV myelofibrosis. Ruxolitinib (RUX) is approved for second-line therapy in high-risk PV pts with hydroxyurea intolerance or resistance. The RuxoBEAT trial (NCT02577926, registered on October 1, 2015, at clinicaltrials.gov) is a multicenter, open-label, two-arm phase-IIb trial with a target population of 380 pts with PV or ET, randomized to receive RUX or best available therapy. This pre-specified futility analysis assesses the early clinical benefit and tolerability of RUX in previously untreated PV pts (6-week cytoreduction was allowed). Twenty-eight patients were randomly assigned to receive RUX. Compared to baseline, after 6 months of treatment, there was a significant reduction of median hematocrit (46 to 41%), the median number of phlebotomies per year (4.0 to 0), and median patient-reported pruritus scores (2 to 1), and a trend for reduced night sweat scores (1.5 to 0). JAK2V617F allele burden, as part of the scientific research program, also significantly decreased. One hundred nine adverse events (AEs) occurred in 24/28 patients (all grade 1 to 3), and no pt permanently discontinued treatment because of AEs. Thus, treatment with ruxolitinib in untreated PV pts is feasible, well-tolerated, and efficient regarding the above-mentioned endpoints.

Step-in dosing of bosutinib in pts with chronic phase chronic myeloid leukemia (CML) after second-generation tyrosine kinase inhibitor (TKI) therapy: results of the Bosutinib Dose Optimization (BODO) Study.

The approved dose of bosutinib in chronic phase CML is 400 mg QD in first-line and 500 mg QD in later-line treatment. However, given that gastrointestinal (GI) toxicity typically occurs early after treatment initiation, physicians often tend to start therapy with lower doses although this has never been tested systematically in prospective trials in the Western world. The Bosutinib Dose Optimization (BODO) Study, a multicenter phase II study, investigated the tolerability and efficacy of a step-in dosing concept of bosutinib (starting at 300 mg QD) in chronic phase CML patients in 2nd or 3rd line who were intolerant and/or refractory to previous TKI treatment. Of 57 patients included until premature closure of the study due to slow recruitment, 34 (60%) reached the targeted dose level of 500 mg QD following the 2-weekly step-in dosing regimen. While the dosing-in concept failed to reduce GI toxicity (grade II-IV, primary study endpoint) to < 40% (overall rate of 60%; 95% CI: 45-74%), bosutinib treatment (mean dosage: 403 mg/day) showed remarkable efficacy with a cumulative major molecular remission (MMR) rate of 79% (95% CI: 66 to 88%) at month 24. Of thirty patients refractory to previous therapy and not in MMR at baseline, 19 (64%) achieved an MMR during treatment. GI toxicity did not significantly impact on patient-reported outcomes (PRO) and led to treatment discontinuation in only one patient. Overall, the results of our trial support the efficacy and safety of bosutinib after failure of second-generation TKI pre-treatment. Trial registration: NCT02577926.

[Implementation of a Pilot Project Supporting Parents Suffering from Cancer with Underage Children]. / Implementierung eines Modellprojektes zur phasenübergreifenden Unterstützung von krebskranken Eltern mit minderjährigen Kindern.

OBJECTIVE: Families with one parent suffering from cancer are exposed to extraordinary emotional and organizational burdens, affecting underaged children. To help coordinated access to social and logistic support options and thus reduce the stress on family members, the project Brückenschlag was founded. The aim of this paper was to evaluate the implementation of this pilot project following the healthcare utilization model by Andersen. METHODS: A cross-sectional observational study was conducted using a mixed-method approach. Semi-structured written expert surveys (n=10) and secondary analysis of routine data of the care model (n=171 families) were combined. RESULTS: Quantitative secondary analysis: The participating families had 1-7 children (median (m) 2, range (s) 6). In 66% of the cases, the mother was affected by cancer, in 20% the diseased parent was in a single parent household. The communication structure in these families was rated "limited" to "rather open". Of the total of 171 contacts (study period 9/14 to 11/17), 133 families made use of Brückenschlag; 59.2% of the contacts were made by psycho-oncologists and the social services department of the hospital. If the contact was initiated by the patients themselves or by psycho-oncologists, a guidance was established significantly more frequently (significance of chi-squared test 0.047). Qualitative analysis: There was a lack of awareness and coordination of existing support services and a lack of family resources to use existing support offers. Both the desired and the established support fell primarily in the area of organizational support. Brückenschlag improved networking and took on a navigating function for the families. CONCLUSION: The data collected indicate that in families, matching the German average in their socio-demographic characteristics, a great need for organizational support develops as soon as one parent becomes sick with cancer. The model project Brückenschlag creates an access to support services for families with one parent suffering from cancer.

KIT D816V Mast Cells Derived from Induced Pluripotent Stem Cells Recapitulate Systemic Mastocytosis Transcriptional Profile.

Mast cells (MCs) represent a population of hematopoietic cells with a key role in innate and adaptive immunity and are well known for their detrimental role in allergic responses. Yet, MCs occur in low abundance, which hampers their detailed molecular analysis. Here, we capitalized on the potential of induced pluripotent stem (iPS) cells to give rise to all cells in the body and established a novel and robust protocol for human iPS cell differentiation toward MCs. Relying on a panel of systemic mastocytosis (SM) patient-specific iPS cell lines carrying the KIT D816V mutation, we generated functional MCs that recapitulate SM disease features: increased number of MCs, abnormal maturation kinetics and activated phenotype, CD25 and CD30 surface expression and a transcriptional signature characterized by upregulated expression of innate and inflammatory response genes. Therefore, human iPS cell-derived MCs are a reliable, inexhaustible, and close-to-human tool for disease modeling and pharmacological screening to explore novel MC therapeutics.

Clonal hematopoiesis in donors and long-term survivors of related allogeneic hematopoietic stem cell transplantation.

Clonal hematopoiesis (CH) is associated with age and an increased risk of myeloid malignancies, cardiovascular risk, and all-cause mortality. We tested for CH in a setting where hematopoietic stem cells (HSCs) of the same individual are exposed to different degrees of proliferative stress and environments, ie, in long-term survivors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and their respective related donors (n = 42 donor-recipient pairs). With a median follow-up time since allo-HSCT of 16 years (range, 10-32 years), we found a total of 35 mutations in 23 out of 84 (27.4%) study participants. Ten out of 42 donors (23.8%) and 13 out of 42 recipients (31%) had CH. CH was associated with older donor and recipient age. We identified 5 cases of donor-engrafted CH, with 1 case progressing into myelodysplastic syndrome in both donor and recipient. Four out of 5 cases showed increased clone size in recipients compared with donors. We further characterized the hematopoietic system in individuals with CH as follows: (1) CH was consistently present in myeloid cells but varied in penetrance in B and T cells; (2) colony-forming units (CFUs) revealed clonal evolution or multiple independent clones in individuals with multiple CH mutations; and (3) telomere shortening determined in granulocytes suggested ∼20 years of added proliferative history of HSCs in recipients compared with their donors, with telomere length in CH vs non-CH CFUs showing varying patterns. This study provides insight into the long-term behavior of the same human HSCs and respective CH development under different proliferative conditions.

Does time from diagnosis to treatment affect the prognosis of patients with newly diagnosed acute myeloid leukemia?

In fit patients with newly diagnosed acute myeloid leukemia (AML), immediate treatment start is recommended due to the poor prognosis of untreated acute leukemia. We explored the relationship between time from diagnosis to treatment start (TDT) and prognosis in a large real-world data set from the German Study Alliance Leukemia-Acute Myeloid Leukemia (SAL-AML) registry. All registered non-acute promyelocytic leukemia patients with intensive induction treatment and a minimum 12 months of follow-up were selected (n = 2263). We analyzed influence of TDT on remission, early death, and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0 to 5, 6 to 10, 11 to 15, and >15 days of TDT, adjusted for influence of established prognostic variables on outcomes. Median TDT was 3 days (interquartile range, 2-7). Unadjusted 2-year OS rates, stratified by TDT of 0 to 5, 6 to 10, 11 to 15, and >15 days, were 51%, 48%, 44%, and 50% (P = .211). In multivariable Cox regression analysis accounting for established prognostic variables, the TDT hazard ratio as a continuous variable was 1.00 (P = .617). In OS analyses, separately stratified for age ≤60 and >60 years and for high vs lower initial white blood cell count, no significant differences between TDT groups were observed. Our study suggests that TDT is not related to survival. As stratification in intensive first-line AML treatment evolves, TDT data suggest that it may be a feasible approach to wait for genetic and other laboratory test results so that clinically stable patients are assigned the best available treatment option. This trial was registered at www.clinicaltrials.gov as #NCT03188874.

Perspective: Pivotal translational hematology and therapeutic insights in chronic myeloid hematopoietic stem cell malignancies.

Despite much of the past 2 years being engulfed by the devastating consequences of the SAR-CoV-2 pandemic, significant progress, even breathtaking, occurred in the field of chronic myeloid malignancies. Some of this was show-cased at the 15th Post-American Society of Hematology (ASH) and the 25th John Goldman workshops on myeloproliferative neoplasms (MPN) held on 9th-10th December 2020 and 7th-10th October 2021, respectively. The inaugural Post-ASH MPN workshop was set out in 2006 by John Goldman (deceased) and Tariq Mughal to answer emerging translational hematology and therapeutics of patients with these malignancies. Rather than present a resume of the discussions, this perspective focuses on some of the pivotal translational hematology and therapeutic insights in these diseases.