The Yin and Yang of the Bone Marrow Microenvironment: Pros and Cons of Mesenchymal Stromal Cells in Acute Myeloid Leukemia

Mesenchymal stromal cells (MSCs) have, for a long time, been recognized as pivotal contributors in the set up and maintenance of the hematopoietic stem cell (HSC) niche, as well as in the development and differentiation of the lympho-hematopoietic system. MSCs also have a unique immunomodulatory capacity, which makes them able to affect, both in vitro and in vivo, the function of immune cells. These features, namely the facilitation of stem cell engraftment and the inhibition of lymphocyte responses, have both proven essential for successful allogeneic stem cell transplantation (allo-SCT), which remains the only curative option for several hematologic malignancies. For example, in steroid-refractory acute graft-vs. host disease developing after allo-SCT, MSCs have produced significant results and are now considered a treatment option. However, more recently, the other side of the MSC coin has been unveiled, because of their emerging role in creating a protective and immune-tolerant microenvironment able to support the survival of leukemic cells and affect the response to therapies. In this light, it has been proposed that the failure of current treatments to efficiently override the stroma-mediated protection of leukemic cells accounts for the high rate of relapse in acute myeloid leukemia, at least in part. In this review, we will focus on emerging microenvironment-driven mechanisms conferring a survival advantage to leukemic cells overt physiological HSCs. This body of evidence increasingly highlights the opportunity to consider tumor-microenvironment interactions when designing new therapeutic strategies

Chemotherapy-Induced Tumor Cell Death at the Crossroads Between Immunogenicity and Immunotolerance: Focus on Acute Myeloid Leukemia

In solid tumors and hematological malignancies, including acute myeloid leukemia, some chemotherapeutic agents, such as anthracyclines, have proven to activate an immune response via dendritic cell-based cross-priming of anti-tumor T lymphocytes. This process, known as immunogenic cell death, is characterized by a variety of tumor cell modifications, i.e., cell surface translocation of calreticulin, extracellular release of adenosine triphosphate and pro-inflammatory factors, such as high mobility group box 1 proteins. However, in addition to with immunogenic cell death, chemotherapy is known to induce inflammatory modifications within the tumor microenvironment, which may also elicit immunosuppressive pathways. In particular, DCs may be driven to acquire tolerogenic features, such as the overexpression of indoleamine 2,3-dioxygensase 1, which may ultimately hamper anti-tumor T-cells via the induction of T regulatory cells. The aim of this review is to summarize the current knowledge about the mechanisms and effects by which chemotherapy results in both activation and suppression of anti-tumor immune response. Indeed, a better understanding of the whole process underlying chemotherapy-induced alterations of the immunological tumor microenvironment has important clinical implications to fully exploit the immunogenic potential of anti-leukemia agents and tune their application

Gene expression profile predicts response to the combination of tosedostat and low-dose cytarabine in elderly AML

Tosedostat is an orally administered metalloenzyme inhibitor with antiproliferative and antiangiogenic activity against hematological and solid human cancers. Clinical activity has been demonstrated in relapsed acute myeloid leukemia (AML). Thirty-three elderly patients with AML (median age, 75 years) received 120 mg tosedostat orally once daily combined with subcutaneous low-dose cytarabine (20 mg twice per day for 10 days, up to 8 cycles), until disease progression. Induction mortality was 12%. According to an intention-to-treat analysis, the complete remission (CR) rate was 48.5%, and thus the primary end point of the study was reached (expected CR, 25%). The partial remission rate was 6.1%, with an overall response rate of 54.5%. Furthermore, 4 of 33 patients had stable disease (median: 286 days). The median progression-free survival and overall survival (OS) were 203 days and 222 days, respectively. Responding patients had a longer median OS than nonresponding patients (P = .001). A microarray analysis performed in 29 of 33 patients identified 188 genes associated with clinical response (CR vs no CR). Three of them (CD93, GORASP1, CXCL16) were validated by quantitative polymerase chain reaction, which correctly classified 83% of the patients. Specifically, CR achievement was efficiently predicted by the gene expression patterns, with an overall accuracy exceeding 90%. Finally, a negative predictive value of 100% was validated in an independent series, thus representing the first molecular predictor for clinical response to a specific combination drug treatment for AML. This trial has been registered at the European Medicines Agency and on the European Clinical Trials Database (https://www.clinicaltrialsregister.eu) as #2012-000334-19

Ultrastructural detection of environmental nanoparticles in circulating blood

The increase in the incidence of acute myeloid leukemia (AML) may suggest a possible environmental etiology. PM2.5 was declared by the International Agency for Research on Cancer (WHO organ) a Class I carcinogen. To date, no reports have focused on particulate environmental pollution together with AML. The study investigated the presence and composition of particulate matter in circulating blood with a Environmental Scanning Electron Microscope coupled with an Energy Dispersive Spectroscope for the elemental analysis of the samples. 38 peripheral blood samples, 19 AML cases and 19 healthy controls, were analysed. A significant overload of particulate matter-derived nanoparticles linked or aggregated to blood components was found in AML patients, while almost absent in matched healthy controls. Two tailed Student’s t-test, MANOVA and Principal Component Analysis indicated that the total numbers of aggregates and particles were statistically different between cases and controls (MANOVA,

Benda-BEAM High-Dose Therapy Prior to Auto-SCT is Effective in Resistant/Relapsed DLBCL

Abstract Background: The most important drawback of clinical trials of high-dose therapy (HDT) followed by autologous stem cell transplant (ASCT) in lymphomas is the high heterogeneity of histological entities. Therefore, the statistical power is reduced, and data are not conclusive. We previously demonstrated the safety of a new conditioning regimen with bendamustine, etoposide, cytarabine, and melphalan (BeEAM) prior to ASCT in resistant/relapsed lymphoma patients. This combination of drugs was able to induce a high CR rate in a population that did not have an opportunity of being cured with other therapies. However, that study enrolled both Hodgkin and non-Hodgkin lymphoma patients. Aims: We designed a phase II study to evaluate the efficacy of the BeEAM conditioning in resistant/relapsed diffuse large B-cell non-Hodgkin lymphoma (DLBCL) patients. Patients and methods: The study was registered at European Union Drug Regulating Authorities Clinical Trials (EudraCT) N. 2011-001246-14. Until now, 61 patients (median age 54 years, range 19-69) with resistant/relapsed DLBCL were enrolled. The primary end-point of the study is to evaluate the 1-year complete remission rate. Results: Briefly, 46/61 patients had advanced stage disease (III-IV); 20 were primary refractory and 41 had relapsed after a median number of 2 lines of therapy (range: 1-3). Twenty-one patients had 1 or more relevant comorbidities (range: 1- 5). 30 patients were in II or subsequent CR after salvage therapy, whereas 27 were in PR and 4 had stable or progressive disease. A median number of 5.72x106 CD34+/kg cells (range 2.21-10.60) collected from peripheral blood was reinfused to patients. All patients engrafted, with a median time to ANC>0.5x109/l of 10 days. Median times to achieve a platelet count >20x109/l and >50x109/l were 12 and 17 days respectively. Twenty-two out of 61 patients presented a fever of unknown origin (36%), whereas 24 patients (39%) presented a clinically documented infection. All patients received G-CSF after transplant for a median time of 8 days (range: 8-13). One patient died due to an incomplete hematological recovery after transplant, producing an overall transplant related mortality of 2.7%. Fifty-seven patients are evaluable for response: 48/57 (84%) obtained a CR, 3/57 (5%) a PR, whereas 6/57 (11%) did not respond to therapy. After a median follow-up of 10.5 months after transplant (range 3-37), 6/57 (11%) patients were refractory, 12/57 (21%) relapsed and 39/57 (68%) are still alive, in continuous CR. Conclusion: Our clinical trial was designed to closely resemble real-world treatment for these patients. During the study, we transplanted a similar proportion of the patients that would have received ASCT in a real-world scenario. While we cannot make sound comparisons without head-to-head trials, results from previous studies using HDT regimens in DLCBL have not been as encouraging as ours. Accordingly, our data preliminary provide the evidence that the Benda-BEAM regimen is safe and has promising high efficacy in resistant-relapsed aggressive DLBCL patients. Acknowledgments: The study was supported in part by AIL Pesaro Onlus. Mundipharma Italy is grateful acknowledged for providing Bendamustine free of charge. Disclosures Patriarca: Janssen-Cilag, Celgene, Merck Sharp & Dohme: Honoraria. Zinzani:Gilead: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; J&J: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees

Genetic profiling in acute myeloid leukemia: a path to predicting treatment outcome

Despite substantial progresses in acute myeloid leukemia (AML) diagnosis and treatment, at least half of patient will eventually die for the disease. In the last decades, the use of genetic and genomic approaches allowed the identification of patients with higher risk of recurrence after and/or resistance to CHT. However, though many novel drugs have been proposed and tested, only little clinical improvements have been made concerning the treatment of the so called 'high risk' patients. Areas covered: In this article, the authors, based on their own experience and the most updated literature, review the basic knowledge of AML prognostication and treatment prediction developed throughout genetic and genomic profiling, and focus on the use of gene expression profiling as a promising predictive tool. The role of next generation sequencing, run on qPCR/digital PCR platforms or polyvalent ones such as the Nanostring NCounter™ and RNA-sequencing techniques in the near future will also be briefly discussed. Expert commentary: The authors believe that a combination of genetic (including both germline and somatic data), epigenetic and transcriptional data will represent, in the future, the molecular basis for treatment decision with the highest predictive potential