Effects of the Autophagy-Inhibiting Agent Chloroquine on Acute Myeloid Leukemia Cells; Characterization of Patient Heterogeneity

Autophagy is a highly conserved cellular degradation process that prevents cell damage and promotes cell survival, and clinical efforts have exploited autophagy inhibition as a therapeutic strategy in cancer. Chloroquine is a well-known antimalarial agent that inhibits late-stage autophagy. We evaluated the effects of chloroquine on cell viability and proliferation of acute myeloid leukemia acute myeloid leukemia (AML) cells derived from 81 AML patients. Our results show that chloroquine decreased AML cell viability and proliferation for the majority of patients. Furthermore, a subgroup of AML patients showed a greater susceptibility to chloroquine, and using hierarchical cluster analysis, we identified 99 genes upregulated in this patient subgroup, including several genes related to leukemogenesis. The combination of chloroquine with low-dose cytarabine had an additive inhibitory effect on AML cell proliferation. Finally, a minority of patients showed increased extracellular constitutive mediator release in the presence of chloroquine, which was associated with strong antiproliferative effects of chloroquine as well as cytarabine. We conclude that chloroquine has antileukemic activity and should be further explored as a therapeutic drug against AML in combination with other cytotoxic or metabolic drugs; however, due to the patient heterogeneity, chloroquine therapy will probably be effective only for selected patients.

Hemophagocytic lymphohistiocytosis in a patient with COVID-19 treated with tocilizumab: a case report

Background

The understanding of coronavirus disease 2019 (COVID-19) is rapidly evolving. Although it is primarily a respiratory illness, other manifestations, such as Guillain-Barré syndrome, immune thrombocytopenia, and immune-mediated thrombotic thrombocytopenic purpura, have been described. We present a case of a patient with hemophagocytic lymphohistiocytosis secondary to COVID-19 treated with tocilizumab with a marked biochemical improvement.

Case presentation

In this case report we present a Caucasian patient with COVID-19 who developed a marked elevation of inflammatory parameters with ferritin 36,023 μg/L, but also elevated C-reactive protein 334 mg/L and lactate dehydrogenase 1074 U/L, 1 week after admission to the intensive care unit. He met five of eight criteria for hemophagocytic lymphohistiocytosis, but he lacked the high fever and cytopenia seen in the majority of cases. He was treated with tocilizumab, a monoclonal antibody targeting the interleukin-6 receptor, and over the next days, a rapid decrease in ferritin and C-reactive protein levels was observed. However, his respiratory failure only improved gradually, and he was weaned off the respirator 11 days later.

Conclusion

COVID-19 may induce a hyperinflammatory clinical picture and in some cases develop into hemophagocytic lymphohistiocytosis. In our patient’s case, therapeutic interleukin-6 blockade abrogated signs of hyperinflammation but did not seem to improve pulmonary function. Measurement of ferritin and C-reactive protein, as well as quantification of interleukin-6 on indication, should be performed in patients with severe COVID-19. Specific treatment in such patients must also be contemplated, preferably in randomized controlled trials.

Targeting Cellular Metabolism in Acute Myeloid Leukemia and The Role of Patient Heterogeneity

Acute myeloid leukemia (AML) is an aggressive blood cancer resulting in accumulation of immature, dysfunctional blood cells in the bone marrow. Changes in cell metabolism are features of many cancers, including AML and this may be exploited as a therapeutic target. In this study we investigated the in vitro antileukemic effects of seven metabolic inhibitors that target different metabolic pathways. The metabolic inhibitors were tested on AML cells derived from 81 patients using proliferation and viability assays; we also compared global gene expression and proteomic profiles for various patient subsets. Metformin, 2DG, 6AN, BPTES and ST1326 had strong antiproliferative and proapoptotic effects for most patients, whereas lonidamine and AZD3965 had an effect only for a minority. Antiproliferative effects on AML cells were additive when combined with the chemotherapeutic agent AraC. Using unsupervised hierarchical clustering, we identified a strong antiproliferative effect on AML cells after treatment with metabolic inhibitors for a subset of 29 patients. Gene expression and proteomic studies suggested that this subset was characterized by altered metabolic and transcriptional regulation. In addition, the Bcl-2 inhibitor venetoclax, in combination with 2DG or 6AN, increased the antiproliferative effects of these metabolic inhibitors on AML cells. Therapeutic targeting of cellular metabolism may have potential in AML, but the optimal strategy will likely differ between patients.

Antileukemic effects of midostaurin in acute myeloid leukemia - the possible importance of multikinase inhibition in leukemic as well as nonleukemic stromal cells

INTRODUCTION

Midostaurin is a multikinase inhibitor that inhibits receptor tyrosine kinases (Flt3, CD117/c-kit, platelet-derived growth factor receptor, vascular endothelial growth factor receptor 2) as well as non-receptor tyrosine kinases (Frg, Src, Syk, Protein kinase C). Combination of midostaurin with conventional intensive chemotherapy followed by one year maintenance monotherapy was recently reported to improve the survival of acute myeloid leukemia (AML) patients with Flt3 mutations. Areas covered: Relevant publications were identified through literature searches in the PubMed database. We searched for (i) original articles describing the results from clinical studies; (ii) published articles describing the importance of midostaurin-inhibited kinases for leukemogenesis and chemosensitivity. Expert opinion: Midostaurin monotherapy is well tolerated, combined with conventional chemotherapy gastrointestinal toxicity increases significantly. Midostaurin alters anthracycline pharmacokinetics. Furthermore, its antileukemic effects may not only be mediated through Flt3 inhibition alone; the inhibition of other kinases may also be important for the overall antileukemic effect. Midostaurin may then have direct effects on the leukemic cells but also indirect antileukemic effects through inhibition of the AML-supporting effects of neighboring stromal cells in the bone marrow microenvironment. Midostaurin may thus be used in combination with intensive chemotherapy, as maintenance treatment or as disease-stabilizing treatment for elderly unfit patients.

Pretransplant Levels of CRP and Interleukin-6 Family Cytokines; Effects on Outcome after Allogeneic Stem Cell Transplantation

Several pretransplant factors, including CRP (C-reactive protein) levels, reflect the risk of complications after allogeneic stem cell transplantation. IL-6 induces CRP increase, and we therefore investigated the effects of pretransplant IL-6, soluble IL-6 receptors, IL-6 family cytokines and CRP serum levels on outcome for 100 consecutive allotransplant recipients. All patients had related donors, none had active infections and 99 patients were in complete remission before conditioning. The incidence of acute graft versus host disease (aGVHD) requiring treatment was 40%, survival at Day +100 82%, and overall survival 48%. Despite a significant correlation between pretransplant CRP and IL-6 levels, only CRP levels significantly influenced transplant-related mortality (TRM). However, CRP did not influence overall survival (OS). Pretransplant IL-31 influenced late TRM. Finally, there was a significant association between pretransplant IL-6 and early postconditioning weight gain (i.e., fluid retention), and this fluid retention was a risk factor for aGVHD, TRM and OS. To conclude, pretransplant CRP, IL-31 and early posttransplant fluid retention were independent risk factors for TRM and survival after allotransplantation.

Targeted high-throughput sequencing for genetic diagnostics of hemophagocytic lymphohistiocytosis

Background

Hemophagocytic lymphohistiocytosis (HLH) is a rapid-onset, potentially fatal hyperinflammatory syndrome. A prompt molecular diagnosis is crucial for appropriate clinical management. Here, we validated and prospectively evaluated a targeted high-throughput sequencing approach for HLH diagnostics.

Methods

A high-throughput sequencing strategy of 12 genes linked to HLH was validated in 13 patients with previously identified HLH-associated mutations and prospectively evaluated in 58 HLH patients. Moreover, 2504 healthy individuals from the 1000 Genomes project were analyzed in silico for variants in the same genes.

Results

Analyses revealed a mutation detection sensitivity of 97.3 %, an average coverage per gene of 98.0 %, and adequate coverage over 98.6 % of sites previously reported as mutated in these genes. In the prospective cohort, we achieved a diagnosis in 22 out of 58 patients (38 %). Genetically undiagnosed HLH patients had a later age at onset and manifested higher frequencies of known secondary HLH triggers. Rare, putatively pathogenic monoallelic variants were identified in nine patients. However, such monoallelic variants were not enriched compared with healthy individuals.

Conclusions

We have established a comprehensive high-throughput platform for genetic screening of patients with HLH. Almost all cases with reduced natural killer cell function received a diagnosis, but the majority of the prospective cases remain genetically unexplained, highlighting genetic heterogeneity and environmental impact within HLH. Moreover, in silico analyses of the genetic variation affecting HLH-related genes in the general population suggest caution with respect to interpreting causality between monoallelic mutations and HLH. A complete understanding of the genetic susceptibility to HLH thus requires further in-depth investigations, including genome sequencing and detailed immunological characterization.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-015-0244-1) contains supplementary material, which is available to authorized users.