Aditi Shastri

IL8-CXCR2 pathway inhibition as a therapeutic strategy against MDS and AML stem cells

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Novel therapeutic targets against preleukemic stem cells need to be identified for potentially curative strategies. We conducted parallel transcriptional analysis of highly fractionated stem and progenitor populations in MDS, AML, and control samples and found interleukin 8 (IL8) to be consistently overexpressed in patient samples. The receptor for IL8, CXCR2, was also significantly increased in MDS CD34(+) cells from a large clinical cohort and was predictive of increased transfusion dependence. High CXCR2 expression was also an adverse prognostic factor in The Cancer Genome Atlas AML cohort, further pointing to the critical role of the IL8-CXCR2 axis in AML/MDS. Functionally, CXCR2 inhibition by knockdown and pharmacologic approaches led to a significant reduction in proliferation in several leukemic cell lines and primary MDS/AML samples via induction of G0/G1 cell cycle arrest. Importantly, inhibition of CXCR2 selectively inhibited immature hematopoietic stem cells from MDS/AML samples without an effect on healthy controls. CXCR2 knockdown also impaired leukemic growth in vivo. Together, these studies demonstrate that the IL8 receptor CXCR2 is an adverse prognostic factor in MDS/AML and is a potential therapeutic target against immature leukemic stem cell-enriched cell fractions in MDS and AML.

The SILK flow diverter in the treatment of intracranial aneurysms

The SILK flow diverter (SFD; Balt Extrusion, Montmorency, France) is a flow diverting stent used in the endovascular treatment of intracranial aneurysms. It works on the principle of redirecting flow away from the aneurysm sac, leading to occlusion over time. We present a systematic review on the clinical outcomes and complications of the SFD. A literature search for English language articles were conducted on PubMed, Medline and EMBASE for articles on the treatment of intracranial aneurysms with the SILK flow diverter. The inclusion criteria were n>10, use of SFD only, data on complications and aneurysm occlusion rate (AOR). Eight studies with 285 patients and 317 intracranial aneurysms were included. The mean age was 52.7 years and nearly 80% were women. In terms of angiographic distribution, 86.8% of aneurysms were located in the anterior circulation and 13.2% in the posterior circulation. As for the aneurysm size, 37.9% were classed as small, 44.4% as large and 17.7% as giant. Ischemic complications and parent artery occlusion each occurred in 10% of patients. Aneurysm rupture rate was 3.5%, while the cumulative mortality was 4.9%. The main outcome measure, 12 month AOR, was 81.8% with complete occlusion in 216 out of 264 aneurysms. Use of flow diverters for the treatment of intracranial aneurysm with complex morphologies has gained in popularity over the last few years. Our review suggests that SFD achieves comparable AOR to its contemporary, the Pipeline Embolization Device (ev3 Endovascular, Plymouth, MN, USA) but has a higher rate of higher rate of ischemic complications, aneurysm rupture and mortality.

Modest activity of pomalidomide in patients with myelofibrosis and significant anemia

We evaluated single agent pomalidomide for myelofibrosis-associated anemia. First, 21 patients received pomalidomide 3.0mg/day on 21-day-on/7-day-off schedule. Due to poor tolerance the study was quickly suspended. Second, 29 patients received pomalidomide 0.5mg/day continuously. Three patients (10%) experienced clinical improvement in hemoglobin per International-Working-Group criteria (median time to response 1.6 months; median response duration 6.7 months). Ten patients were RBC-transfusion-dependent per Delphi criteria; 2 (20%) achieved RBC-transfusion-independence (time to response 0.9 months in both; response duration of 8.3 and 15 months). One grade 3/4 toxicity (neutropenia) occurred. Pomalidomide at low dose is well tolerated but has modest clinical activity in myelofibrosis.

Thrombolysis for Acute Ischemic Stroke in Patients With Cancer: A Population Study

Background and Purpose— The safety of thrombolysis for acute stroke in patients with cancer is not well established. Our aim is to study the outcomes after thrombolysis in patients with stroke with cancer. Methods— Patients with acute ischemic stroke who received thrombolysis were identified from the 2009 and 2010 Nationwide Inpatient Sample. Patients with cancer-associated strokes and noncancer strokes were compared based on demographics, comorbidities, and outcomes. Results— Of the 32 576 strokes treated with thrombolysis, cancer-associated strokes had significantly higher comorbidity indices overall, but fewer vascular risk factors than noncancer strokes. There was no difference in the rates of home discharge and in-hospital mortality, after adjusting for confounders. Subgroup analysis showed that compared with liquid cancers, patients with solid tumors had worse home discharge (odds ratio, 0.178; 95% confidence interval, 0.109–0.290; P<0.001) and higher in-hospital mortality (odds ratio, 3.018; 95% confidence interval, 1.37–6.646; P=0.006) after thrombolysis. Metastatic cancers had poorest outcomes, but intracerebral hemorrhage rates were similar. Conclusions— Thrombolytic therapy for acute stroke in patients with cancer is not associated with increased risk of intracerebral hemorrhage or in-hospital mortality. However, careful consideration of the cancer subtype may help delineate the subset of patients with poor response to thrombolysis. Prospective confirmation is warranted.

Phase II study of pomalidomide in combination with prednisone in patients with myelofibrosis and significant anemia

We evaluated pomalidomide with prednisone for myelofibrosis (MF) with significant anemia (hemoglobin < 10 g/dL). Patients (n = 29; 18 RBC-transfusion dependent) received 0.5mg pomalidomide daily in continuous 28-day cycles with prednisone given for the first 3 cycles only. Six (21%) patients responded (median response duration 11.4 months), including four who achieved RBC-transfusion-independence per the Delphi criteria and two who achieved clinical improvement (in platelets and spleen, respectively) per the International Working Group for Myelofibrosis Research and Treatment criteria. Grade 3 toxicity occurred in 1 patient (fatigue). Pomalidomide with prednisone is safe therapy with modest activity in patients with MF and anemia. ClinicalTrials.gov Identifier: NCT00946270.

Stem and progenitor cell alterations in myelodysplastic syndromes

Recent studies have demonstrated that myelodysplastic syndromes (MDSs) arise from a small population of disease-initiating hematopoietic stem cells (HSCs) that persist and expand through conventional therapies and are major contributors to disease progression and relapse. MDS stem and progenitor cells are characterized by key founder and driver mutations and are enriched for cytogenetic alterations. Quantitative alterations in hematopoietic stem and progenitor cell (HSPC) numbers are also seen in a stage-specific manner in human MDS samples as well as in murine models of the disease. Overexpression of several markers such as interleukin-1 (IL-1) receptor accessory protein (IL1RAP), CD99, T-cell immunoglobulin mucin-3, and CD123 have begun to differentiate MDS HSPCs from healthy counterparts. Overactivation of innate immune components such as Toll-like receptors, IL-1 receptor-associated kinase/tumor necrosis factor receptor-associated factor-6, IL8/CXCR2, and IL1RAP signaling pathways has been demonstrated in MDS HSPCs and is being targeted therapeutically in preclinical and early clinical studies. Other dysregulated pathways such as signal transducer and activator of transcription 3, tyrosine kinase with immunoglobulinlike and EGF-like domains 1/angiopoietin-1, p21-activated kinase, microRNA 21, and transforming growth factor β are also being explored as therapeutic targets against MDS HSPCs. Taken together, these studies have demonstrated that MDS stem cells are functionally critical for the initiation, transformation, and relapse of disease and need to be targeted therapeutically for future curative strategies in MDSs.

Pexmetinib: A Novel Dual Inhibitor of Tie2 and p38 MAPK with Efficacy in Preclinical Models of Myelodysplastic Syndromes and Acute Myeloid Leukemia.

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) suppress normal hematopoietic activity in part by enabling a pathogenic inflammatory milieu in the bone marrow. In this report, we show that elevation of angiopoietin-1 in myelodysplastic CD34(+) stem-like cells is associated with higher risk disease and reduced overall survival in MDS and AML patients. Increased angiopoietin-1 expression was associated with a transcriptomic signature similar to known MDS/AML stem-like cell profiles. In seeking a small-molecule inhibitor of this pathway, we discovered and validated pexmetinib (ARRY-614), an inhibitor of the angiopoietin-1 receptor Tie-2, which was also found to inhibit the proinflammatory kinase p38 MAPK (which is overactivated in MDS). Pexmetinib inhibited leukemic proliferation, prevented activation of downstream effector kinases, and abrogated the effects of TNFα on healthy hematopoietic stem cells. Notably, treatment of primary MDS specimens with this compound stimulated hematopoiesis. Our results provide preclinical proof of concept for pexmetinib as a Tie-2/p38 MAPK dual inhibitor applicable to the treatment of MDS/AML. Cancer Res; 76(16); 4841-9. ©2016 AACR.

In-hospital outcomes of thrombolysis for acute ischemic stroke in patients with primary brain tumors

Data on thrombolysis outcomes in patients with primary brain tumors are limited. Our aim was to study stroke outcomes following thrombolysis in these patients in a population-based study. Patients with acute ischemic stroke who received thrombolysis were identified from the 2002-2011 USA Nationwide Inpatient Sample. We compared demographics, comorbidities, and outcomes between primary brain tumor-associated strokes (BTS) and non-brain tumor associated strokes (NBTS). The main outcomes were inpatient mortality, home discharge and intracranial hemorrhage (ICH) rate. Of the 124,083 thrombolysis-treated stroke patients, 416 (0.34%) had brain tumors. In adjusted analysis, inpatient mortality (odds ratio [OR]: 0.98; 95% confidence interval [CI]: 0.77-1.26, p=0.918), rate of home discharge (OR: 1.15; 95% CI: 0.87-1.53, p=0.40) and rate of ICH (OR: 0.94; 95% CI: 0.62-1.44, p=0.801) were similar between BTS and NBTS. Analysis of brain tumor subtypes showed that compared to NBTS, malignant BTS were independently associated with higher in-hospital mortality (OR: 2.51; 95% CI: 1.66-3.79, p<0.001), lower home discharge (OR: 0.36, 95% CI: 0.18-0.72, p=0.004), and increased risk of ICH (OR: 2.33, 95% CI: 1.49-3.65, p<0.001). Additionally, among the BTS, intraparenchymal location of tumor was associated with higher mortality (OR: 2.51; 95% CI: 1.20-5.23, p=0.014) and lower home discharge (OR: 0.26; 95% CI: 0.13-0.53, p<0.001). Thrombolytic therapy for acute stroke appears to be safe in patients with primary brain tumors, with similar rates of ICH. Malignant BTS have worse outcomes, while benign BTS have outcomes comparable to NBTS. Careful consideration of tumor pathology may aid selection of patients with poor thrombolysis outcomes.

High prevalence and allele burden-independent prognostic importance of p53 mutations in an inner-city MDS/AML cohort

High prevalence and allele burden-independent prognostic importance of p53 mutations in an inner-city MDS/AML cohort

Adult T-cell leukemia/lymphoma in the Caribbean cohort is a distinct clinical entity with dismal response to conventional chemotherapy

Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive disease caused by human T-cell lymphotropic virus type 1 that predominantly affects Japanese and Caribbean populations. Most studies have focused on Japanese cohorts. We conducted a retrospective analysis of 53 cases of ATLL who presented to our institution between 2003-2014. ATLL in the Caribbean population presents more often as the acute and lymphomatous subtypes, is associated with complex cytogenetics, and has a high rate of CNS involvement. The overall response rate to first-line therapies with anthracycline-based regimens was poor (32%), with a median survival of only 6.9 months. A complete or partial response to first-line regimens was associated with better survival. There was no difference in survival between patients who received chemotherapy alone versus chemotherapy with antiviral agents. Allogeneic transplantation was performed in five patients, two of whom achieved complete remission despite residual or refractory disease. Recipients of allogeneic transplantation had significantly improved overall survival compared to non-transplanted patients. This is the first analysis to describe ATLL pathological features, cytogenetics, and response to standard therapy and transplantation in the Caribbean cohort.