Michel van Gelder

High Prognostic Impact of Flow Cytometric Minimal Residual Disease Detection in Acute Myeloid Leukemia: Data From the HOVON/SAKK AML 42A Study

PURPOSE Half the patients with acute myeloid leukemia (AML) who achieve complete remission (CR), ultimately relapse. Residual treatment-surviving leukemia is considered responsible for the outgrowth of AML. In many retrospective studies, detection of minimal residual disease (MRD) has been shown to enable identification of these poor-outcome patients by showing its independent prognostic impact. Most studies focus on molecular markers or analyze data in retrospect. This study establishes the value of immunophenotypically assessed MRD in the context of a multicenter clinical trial in adult AML with sample collection and analysis performed in a few specialized centers. PATIENTS AND METHODS In adults (younger than age 60 years) with AML enrolled onto the Dutch-Belgian Hemato-Oncology Cooperative Group/Swiss Group for Clinical Cancer Research Acute Myeloid Leukemia 42A study, MRD was evaluated in bone marrow samples in CR (164 after induction cycle 1, 183 after cycle 2, 124 after consolidation therapy). RESULTS After all courses of therapy, low MRD values distinguished patients with relatively favorable outcome from those with high relapse rate and adverse relapse-free and overall survival. In the whole patient group and in the subgroup with intermediate-risk cytogenetics, MRD was an independent prognostic factor. Multivariate analysis after cycle 2, when decisions about consolidation treatment have to be made, confirmed that high MRD values (> 0.1% of WBC) were associated with a higher risk of relapse after adjustment for consolidation treatment time-dependent covariate risk score and early or later CR. CONCLUSION In future treatment studies, risk stratification should be based not only on risk estimation assessed at diagnosis but also on MRD as a therapy-dependent prognostic factor.

Managing high-risk CLL during transition to a new treatment era: stem cell transplantation or novel agents?

Allogeneic hematopoietic stem cell transplantation (HSCT) has been considered as the treatment of choice for patients with high-risk chronic lymphocytic leukemia (HR-CLL; ie, refractory to purine analogs, short response [<24 months] to chemoimmunotherapy, and/or presence of del[17p]/TP53 mutations). Currently, treatment algorithms for HR-CLL are being challenged by the introduction of novel classes of drugs. Among them, BCR signal inhibitors (BCRi) and B-cell lymphoma 2 antagonists (BCL2a) appear particularly promising. As a result of the growing body of favorable outcome data reported for BCRi/BCL2a, uncertainty is emerging on how to advise patients with HR-CLL about indication for and timing of HSCT. This article provides an overview of currently available evidence and theoretical considerations to guide this difficult decision process. Until the risks and benefits of different treatment strategies are settled, all patients with HR-CLL should be considered for treatment with BCRi/BCL2a. For patients who respond to these agents, there are 2 treatment possibilities: (1) performing an HSCT or (2) continuing treatment with the novel drug. Individual disease-specific and transplant-related risk factors, along with patients preferences, should be taken into account when recommending one of these treatments over the other.

Hypoxia Induced Impairment of NK Cell Cytotoxicity against Multiple Myeloma Can Be Overcome by IL-2 Activation of the NK Cells

Background Multiple Myeloma (MM) is an incurable plasma cell malignancy residing within the bone marrow (BM). We aim to develop allogeneic Natural Killer (NK) cell immunotherapy for MM. As the BM contains hypoxic regions and the tumor environment can be immunosuppressive, we hypothesized that hypoxia inhibits NK cell anti-MM responses. Methods NK cells were isolated from healthy donors by negative selection and NK cell function and phenotype were examined at oxygen levels representative of hypoxic BM using flowcytometry. Additionally, NK cells were activated with IL-2 to enhance NK cell cytotoxicity under hypoxia. Results Hypoxia reduced NK cell killing of MM cell lines in an oxygen dependent manner. Under hypoxia, NK cells maintained their ability to degranulate in response to target cells, though, the percentage of degranulating NK cells was slightly reduced. Adaptation of NK- or MM cells to hypoxia was not required, hence, the oxygen level during the killing process was critical. Hypoxia did not alter surface expression of NK cell ligands (HLA-ABC, -E, MICA/B and ULBP1-2) and receptors (KIR, NKG2A/C, DNAM-1, NCRs and 2B4). It did, however, decrease expression of the activating NKG2D receptor and of intracellular perforin and granzyme B. Pre-activation of NK cells by IL-2 abrogated the detrimental effects of hypoxia and increased NKG2D expression. This emphasized that activated NK cells can mediate anti-MM effects, even under hypoxic conditions. Conclusions Hypoxia abolishes the killing potential of NK cells against multiple myeloma, which can be restored by IL-2 activation. Our study shows that for the design of NK cell-based immunotherapy it is necessary to study biological interactions between NK- and tumor cells also under hypoxic conditions.

Allogeneic hematopoietic stem cell transplantation for MDS and CMML: recommendations from an international expert panel.

An international expert panel, active within the European Society for Blood and Marrow Transplantation, European LeukemiaNet, Blood and Marrow Transplant Clinical Trial Group, and the International Myelodysplastic Syndromes Foundation developed recommendations for allogeneic hematopoietic stem cell transplantation (HSCT) in myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). Disease risks scored according to the revised International Prognostic Scoring System (IPSS-R) and presence of comorbidity graded according to the HCT Comorbidity Index (HCT-CI) were recognized as relevant clinical variables for HSCT eligibility. Fit patients with higher-risk IPSS-R and those with lower-risk IPSS-R with poor-risk genetic features, profound cytopenias, and high transfusion burden are candidates for HSCT. Patients with a very high MDS transplantation risk score, based on combination of advanced age, high HCT-CI, very poor-risk cytogenetic and molecular features, and high IPSS-R score have a low chance of cure with standard HSCT and consideration should be given to treating these patients in investigational studies. Cytoreductive therapy prior to HSCT is advised for patients with ≥10% bone marrow myeloblasts. Evidence from prospective randomized clinical trials does not provide support for specific recommendations on the optimal high intensity conditioning regimen. For patients with contraindications to high-intensity preparative regimens, reduced intensity conditioning should be considered. Optimal timing of HSCT requires careful evaluation of the available effective nontransplant strategies. Prophylactic donor lymphocyte infusion (DLI) strategies are recommended in patients at high risk of relapse after HSCT. Immune modulation by DLI strategies or second HSCT is advised if relapse occurs beyond 6 months after HSCT.

Klebsiella pneumoniae-triggered DC recruit human NK cells in a CCR5-dependent manner leading to increased CCL19-responsiveness and activation of NK cells.

Besides their role in destruction of altered self‐cells, NK cells have been shown to potentiate T‐cell responses by interacting with DC. To take advantage of NK–DC crosstalk in therapeutic DC‐based vaccination for infectious diseases and cancer, it is essential to understand the biology of this crosstalk. We aimed to elucidate the in vitro mechanisms responsible for NK‐cell recruitment and activation by DC during infection. To mimic bacterial infection, DC were exposed to a membrane fraction of Klebsiella pneumoniae, which triggers TLR2/4. DC matured with these bacterial fragments can actively recruit NK cells in a CCR5‐dependent manner. An additional mechanism of DC‐induced NK‐cell recruitment is characterized by the induction of CCR7 expression on CD56dimCD16+ NK cells after physical contact with membrane fraction of K. pneumoniae‐matured DC, resulting in an enhanced migratory responsiveness to the lymph node‐associated chemokine CCL19. Bacterial fragment‐matured DC do not only mediate NK‐cell migration but also meet the prerequisites needed for augmentation of NK‐cell cytotoxicity and IFN‐γ production, the latter of which contributes to Th1 polarization.

Incidence and management of toxicity associated with ibrutinib and idelalisib: a practical approach

The use of novel B-cell receptor signaling inhibitors results in high response rates and long progression-free survival in patients with indolent B-cell malignancies, such as chronic lymphocytic leukemia, follicular lymphoma, mantle cell lymphoma and Waldenström macroglobulinemia. Ibrutinib, the first-in-class inhibitor of Bruton tyrosine kinase, and idelalisib, the first-in-class inhibitor of phosphatidylinositol 3-kinase δ, have recently been approved for the treatment of several indolent B-cell malignancies. These drugs are especially being used for previously unmet needs, i.e., for patients with relapsed or refractory disease, high-risk cytogenetic or molecular abnormalities, or with comorbidities. Treatment with ibrutinib and idelalisib is generally well tolerated, even by elderly patients. However, the use of these drugs may come with toxicities that are distinct from the side effects of immunochemotherapy. In this review we discuss the most commonly reported and/or most clinically relevant adverse events associated with these B-cell receptor inhibitors, with special emphasis on recommendations for their management.

Compartmentalization of Acyclovir-Resistant Varicella Zoster Virus: Implications for Sampling in Molecular Diagnostics

BACKGROUND Acyclovir resistance of varicella zoster virus (VZV) may arise in stem cell transplant (SCT) recipients with VZV disease and is usually a result of mutations in VZV thymidine kinase (TK), which is the target protein of acyclovir. Early detection of such mutations is necessary to enable timely therapy adaptation, for example, to foscarnet. We aimed to investigate whether TK mutations arise over time, and what sample types might be the most useful for this method. METHODS Spatially and temporally distinct samples from 3 SCT recipients with VZV disease unresponsive to acyclovir treatment were retrospectively investigated for the presence of TK mutations by polymerase chain reaction and sequence analysis. RESULTS In all 3 patients, a mutation in the VZV TK coding region was found resulting in an amino acid substitution. TK mutations were not only temporally but also spatially compartmentalized. In particular, plasma samples frequently showed wild-type TK sequences, whereas cerebrospinal fluid or skin vesicle fluid acquired on the same day contained mutant sequences. CONCLUSIONS This study shows the importance of careful sampling for molecular diagnostics of acyclovir resistance in VZV disease. All affected body sites should be sampled and plasma samples may not be representative for the viral mutation status.

Comparison of allogeneic stem cell transplantation and non-transplant approaches in elderly patients with advanced myelodysplastic syndrome: optimal statistical approaches and a critical appraisal of clinical results using non-randomized data.

Allogeneic stem cell transplantation (ASCT) from related or unrelated donors may cure patients with myelodysplastic syndromes (MDS), a heterogeneous group of clonal stem cell disorders. We analysed 384 elderly patients (55-69 years) with advanced MDS who received either ASCT (n=247) and were reported to The European Group for Blood and Marrow Transplantation (EBMT) or a non –transplant approach (n=137) reported to the Düsseldorf registry. Besides an attempt to answer the question of „comparison“, the purpose of this work is to explain the difficulties in comparing a non-transplant with a transplant cohort, when death before transplant is likely but unknown and the selection of patients for transplant is based on assumptions. It shows which methods are almost always biased and that even the most sophisticated approaches crucially rely on clinical assumptions. Using the most appropriate model for our data, we derive an overall univariate non-significant survival disadvantage for the transplant cohort (HR: 1.29, p = 0.11). We show that such an “average” hazard ratio is however misleading due to non-proportionality of the hazards reflecting early treatment related mortality, the occurring of which is logically correlated with the interval between diagnosis and transplant creating a disproportional drop in the (reconstructed) survival curve of the transplanted patients. Also in multivariate analysis (correcting for age > 60 (HR: 1.4, p = 0.02) and abnormal cytogenetics (HR: 1.46, p = 0.01)), transplantation seems to be worse (HR: 1.39, p = 0.05) but only in the (incorrect but commonly applied) model without time varying covariates. The long term (time depending) hazard ratio is shown to be virtually 1 and overall survival is virtually identical in both groups. Nonetheless no conclusion can be reached from a clinical point of view without assumptions which are by their very nature untestable unless all patients would be followed from diagnosis.

Improved relapse‐free survival after autologous stem cell transplantation does not translate into better quality of life in chronic lymphocytic leukemia: Lessons from the randomized European Society for Blood and Marrow Transplantation‐Intergroup study

In chronic lymphocytic leukemia (CLL) medical progress is driven by clinical studies with relapse‐free survival (RFS) as the primary endpoint. The randomized EBMT‐Intergroup trial compared high‐dose therapy and autologous stem cell transplantation (ASCT) to observation and demonstrated a substantial improvement of RFS without showing improved overall survival for the transplant arm. Here we report quality of life (QoL) information of the first 3 years following randomization from that study. The main objective was to assess the impact of treatment on QoL over time. Two secondary analyses were performed to further investigate the impact of ASCT and relapse on QoL. In the primary analysis, we demonstrate an adverse impact of ASCT on QoL which was largest at 4 months and continued throughout the first year after randomization. Further, we demonstrated a sustained adverse impact of relapse on QoL which worsened over time. Despite better disease control by ASCT the side effects thus turned the net effect towards inferior QoL in the first year and comparable QoL in the following 2 years after randomization. This study emphasizes the importance of information concerning QoL impacts when patients are counseled about treatments aimed at improving RFS in the absence of a survival benefit. Am. J. Hematol. 89:174–180, 2014.

Centre characteristics and procedure-related factors have an impact on outcomes of allogeneic transplantation for patients with CLL: a retrospective analysis from the European Society for Blood and Marrow Transplantation (EBMT)

The best approach for allogeneic haematopoietic stem cell transplantations (alloHCT) in patients with chronic lymphocytic leukaemia (CLL) is unknown. We therefore analysed the impact of procedure‐ and centre‐related factors on 5‐year event‐free survival (EFS) in a large retrospective study. Data of 684 CLL patients who received a first alloHCT between 2000 and 2011 were analysed by multivariable Cox proportional hazards models with a frailty component to investigate unexplained centre heterogeneity. Five‐year EFS of the whole cohort was 37% (95% confidence interval [CI], 34–42%). Larger numbers of CLL alloHCTs (hazard ratio [HR] 0·96, P = 0·002), certification of quality management (HR 0·7, P = 0·045) and a higher gross national income per capita (HR 0·4, P = 0·04) improved EFS. In vivo T‐cell depletion (TCD) with alemtuzumab compared to no TCD (HR 1·5, P = 0·03), and a female donor compared to a male donor for a male patient (HR 1·4, P = 0·02) had a negative impact on EFS, but not non‐myeloablative versus more intensive conditioning. After correcting for patient‐, procedure‐ and centre‐characteristics, significant variation in centre outcomes persisted. In conclusion, further research on the impact of centre and procedural characteristics is warranted. Non‐myeloablative conditioning appears to be the preferable approach for patients with CLL.