The crosstalk between non-coding RNAs and cell-cycle events: A new frontier in cancer therapy

The cell cycle comprises sequential events during which a cell duplicates its genome and divides it into two daughter cells. This process is tightly regulated to ensure that the daughter cell receives identical copied chromosomal DNA and that any errors in the DNA during replication are correctly repaired. Cyclins and their enzyme partners, cyclin-dependent kinases (CDKs), are critical regulators of G- to M-phase transitions during the cell cycle. Mitogenic signals induce the formation of the cyclin/CDK complexes, resulting in phosphorylation and activation of the CDKs. Once activated, cyclin/CDK complexes phosphorylate specific substrates that drive the cell cycle forward. The sequential activation and inactivation of cyclin-CDK complexes are tightly controlled by activating and inactivating phosphorylation events induced by cell-cycle proteins. The non-coding RNAs (ncRNAs), which do not code for proteins, regulate cell-cycle proteins at the transcriptional and translational levels, thereby controlling their expression at different cell-cycle phases. Deregulation of ncRNAs can cause abnormal expression patterns of cell-cycle-regulating proteins, resulting in abnormalities in cell-cycle regulation and cancer development. This review explores how ncRNA dysregulation can disrupt cell division balance and discusses potential therapeutic approaches targeting these ncRNAs to control cell-cycle events in cancer treatment.

Lessons learned from COVID-19 pandemic: outcomes after SARS-CoV-2 infection in hematopoietic cell transplant and cell therapy recipients

We investigated the outcomes after Coronavirus disease 2019 (COVID) in hematopoietic cell transplant (HCT) or chimeric antigen receptor-T cell (CART) therapy recipients in a single-centre study including all (n = 261)HCT/CART recipients (allogeneic-HCT 49%, autologous-HCT 40%, CART 11%). The median age was 60 (22-80) years. COVID severity was mild (74%), moderate (11%), and severe/critical (16%) with a mortality rate of 7% and a median duration of infection of 5.7 weeks. Significant predictors of COVID severe disease or mortality included concurrent infection (HR 14.9, 95% CI 2.2-5.6) and immunosuppressive therapy (OR 4.8, 95% CI 1.2-3.4).HCT/CART recipients have a higher risk of mortality with COVID and warrant vigilant interventions.

Use of endpoints in phase III randomized controlled trials for acute myeloid leukemia over the last 15 years: a systematic review

We systematically evaluated the primary and secondary endpoints used in acute myeloid leukemia (AML) phase III randomized controlled trials (RCTs). We included 238 phase III AML RCTs in the past 15 years that reported 279 primary endpoints and 657 secondary endpoints. Overall survival (OS), progression-free survival (PFS), event-free survival (EFS), and complete remission (CR) were primary endpoints in 120 (43%), 34 (12%), 30 (11%), and 41 (15%) studies, respectively. OS (12.5%), PFS (13.2%), CR (14%), safety (11%), and EFS (9%) were commonly reported secondary endpoints. Among primary endpoints, a higher use of OS (OR 2.03, 95%CI 1.10-3.75, p = 0.023) and lower use of PFS (OR 0.25, 95%CI 0.12-0.52, p < 0.001) was observed from 2014 to 2021 compared to 2006-2013; CR was frequently used in relapsed/refractory compared to frontline RCTs (OR 2.20, 95%CI 1.11-4.38, p = 0.025); EFS was frequently used in frontline compared to relapsed/refractory AML RCTs (OR 10.11, 95%CI 1.34-76.34, p = 0.025). A higher trend in the use of clinically meaningful and objective endpoint of OS over the last 15 years.

Outcomes with allogeneic hematopoietic stem cell transplantation in TP53-mutated acute myeloid leukemia: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis to evaluate outcomes after allogeneic hematopoietic stem cell transplantation (HSCT) in TP53-mutated acute myeloid leukemia (AML). We performed a literature search on PubMed, Embase, Cochrane Library, and ClinicalTrials.gov. After screening 592 manuscripts, eight studies were included. Data were extracted following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Pooled analysis was done using the meta-package by Schwarzer et al. Proportions with 95% confidence intervals (CIs) were computed. We analyzed 297 patients. The median follow-up was 45 (0.9-407.3) months. The pooled 2-year overall survival was 29.7% (95% CI 0.17-0.43, n = 82/248). The pooled relapse rate was 61.4% (95% CI 0.41-0.79, n = 139/247) at a median follow-up time of 2 (0.26-3) years. Three-year progression-free survival and non-relapse mortality were reported by one study as 7.5% and 32.5%, respectively. Outcomes of HSCT for TP53-mutated AML are poor; however, HSCT confers a survival advantage as compared to non-transplant palliative therapies.

Glutathione peroxidase 4 inhibition induces ferroptosis and mTOR pathway suppression in thyroid cancer

Papillary thyroid carcinoma (PTC) demonstrates significantly reduced patient survival with metastatic progression. Tumor progression can be influenced by metabolism, including antioxidant glutathione (GSH). Glutathione peroxidase 4 (GPX4) is a selenoenzyme that uses GSH as a co-factor to regulate lipid peroxidation of cell membranes during increased oxidative stress. GPX4 suppression in tumor cells can induce ferroptosis. This study aims to examine ferroptosis as a potentially critical pathway in effective targeting of thyroid cancer (TC) cells. We treated human TC cells (K1, MDA-T68, MDA-T32, TPC1) with (1S,3R)-RSL3 (RSL3), a small-molecule inhibitor of GPX4 and examined the effects on ferroptosis, tumor cell survival and migration, spheroid formation, oxidative stress, DNA damage repair response, and mTOR signaling pathway in vitro. GPX4 inhibition activated ferroptosis, inducing TC cell death, rapid rise in reactive oxygen species and effectively arrested cell migration in vitro. Suppression of mTOR signaling pathway triggered autophagy. GPX4 genetic knockdown mirrored RSL3 effect on mTOR pathway suppression. RSL3 subdued DNA damage repair response by suppressing phosphorylation of nucleophosmin 1 (NPM1). Thus, observed potent induction of ferroptosis, GPX4-dependent novel suppression of mTOR pathway and DNA damage repair response in preclinical in vitro model of TC supports GPX4 targeting for therapeutic benefit in advanced therapy-resistant thyroid cancers.

Impact of natural killer cells on outcomes after allogeneic hematopoietic stem cell transplantation: A systematic review and meta-analysis

Background

Natural killer (NK) cells play a vital role in early immune reconstitution following allogeneic hematopoietic stem cell transplantation (HSCT).

Methods

A literature search was performed on PubMed, Cochrane, and Clinical trials.gov through April 20, 2022. We included 21 studies reporting data on the impact of NK cells on outcomes after HSCT. Data was extracted following the PRISMA guidelines. Pooled analysis was done using the meta-package (Schwarzer et al.). Proportions with 95% confidence intervals (CI) were computed.

Results

We included 1785 patients from 21 studies investigating the impact of NK cell reconstitution post-HSCT (8 studies/1455 patients), stem cell graft NK cell content (4 studies/185 patients), therapeutic NK cell infusions post-HSCT (5 studies/74 patients), and pre-emptive/prophylactic NK cell infusions post-HSCT (4 studies/77 patients). Higher NK cell reconstitution was associated with a better 2-year overall survival (OS) (high: 77%, 95%CI 0.73-0.82 vs low: 55%, 95%CI 0.37-0.72; n=899), however, pooled analysis for relapse rate (RR) or graft versus host disease (GVHD) could not be performed due to insufficient data. Higher graft NK cell content demonstrated a trend towards a better pooled OS (high: 65.2%, 95%CI 0.47-0.81 vs low: 46.5%, 95%CI 0.24-0.70; n=157), lower RR (high: 16.9%, 95%CI 0.10-0.25 vs low: 33%, 95%CI 0.04-0.72; n=157), and lower acute GVHD incidence (high: 27.6%, 95%CI 0.20-0.36 vs low: 49.7%, 95%CI 0.26-0.74; n=157). Therapeutic NK or cytokine-induced killer (CIK) cell infusions for hematologic relapse post-HSCT reported an overall response rate (ORR) and complete response (CR) of 48.9% and 11% with CIK cell infusions and 82.8% and 44.8% with NK cell infusions, respectively. RR, acute GVHD, and chronic GVHD were observed in 55.6% and 51.7%, 34.5% and 20%, and 20.7% and 11.1% of patients with CIK and NK cell infusions, respectively. Pre-emptive donor-derived NK cell infusions to prevent relapse post-HSCT had promising outcomes with 1-year OS of 69%, CR rate of 42%, ORR of 77%, RR of 28%, and acute and chronic GVHD rates of 24.9% and 3.7%, respectively.

Conclusion

NK cells have a favorable impact on outcomes after HSCT. The optimal use of NK cell infusions post-HSCT may be in a pre-emptive fashion to prevent disease relapse.

Impact of SARS-CoV-2 in Hematopoietic Stem Cell Transplantation and Chimeric Antigen Receptor T Cell Therapy Recipients

Coronavirus disease 2019 (COVID-19), a respiratory illness caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a pandemic in March 2020, and has caused more than 600,000 deaths in the United States at the time of this report. Hematopoietic stem cell transplantation (HCT) or chimeric antigen receptor T cell (CAR-T) therapy recipients have a higher risk of mortality with COVID-19 owing to profound immune dysregulation. In this study, we investigated the impact of SARS-CoV-2 in HCT/CAR-T therapy recipients. This single-center prospective study included all (n = 58) adult HCT/CAR-T recipients who were diagnosed with COVID-19 at the University of Kansas Medical Center between March 2020 and May 2021. Baseline and disease-related characteristics were ascertained from medical records. Data were analyzed using SPSS version 21 (IBM, Armonk, NY). Bivariate analyses, using the chi-square and t-test, and logistic regression analyses were conducted. The study included 58 HCT/CAR-T patients who acquired SARS-CoV-2 infection, including recipients of allogeneic HCT (n = 32), autologous HCT (n = 23), and CAR-T therapy (n = 3). The median patient age was 58 years (range, 24 to 77 years), and 64% were males. The median time from HCT/CAR-T therapy to SARS-CoV-2 infection was 17.7 months (range, 0.2 to 201.9 months), and 22% of the patients acquired SARS-CoV-2 within the first 100 days post-HCT/CAR-T therapy. The primary hematologic disorders were plasma cell (36%), myeloid (38%), and lymphoid (26%) malignancies. Myeloablative conditioning was performed in 62% of patients. Donors were autologous (45%), matched sibling (15%), matched unrelated (21%), and haploidentical (19%). Prior history of grade II-IV acute graft-versus-host disease (GVHD), active GVHD, and current immunosuppressive therapy (IST) was noted in 22%, 31%, and 36% of patients, respectively. Concurrent infections were observed in 19%. Lymphopenia (P = .049) and high serum ferritin concentration (P = .020) were associated with mortality. COVID-19 severity was mild in 50% of the patients, moderate in 22%, and severe in 28%. Clinical findings included pneumonia or abnormal chest imaging (in 50%), hypoxia (28%), intensive care unit admission (19%), and mechanical ventilation (10%). Therapies included remdesivir (in 41%), convalescent plasma (35%), dexamethasone (22%), monoclonal antibodies (19%), and tocilizumab (3%). The median duration of viral shedding (positive SARS-CoV-2 PCR) was 7.7 weeks (range, 2 to 18.7 weeks), and 2 patients had a persistent infection for >5 months post-CAR-T therapy. After a median follow-up of 6.1 months (range, 0.5-13.6 months), the mortality rate was 16% in all patients and 28% in allogeneic HCT recipients. Among 9 patients who died, the median survival after SARS-CoV-2 infection was 23 days (range, 14 to 140 days). In survivors with moderate-severe COVID-19, the median time to recovery was 4.2 weeks (range, 1.1 to 24.7 weeks). Among allogeneic HCT recipients, 5 (16%) developed subsequent pulmonary chronic GVHD necessitating systemic steroids and additional IST. Significant predictors of COVID-19 severity included allogeneic HCT (odds ratio [OR], 3.6, 95% confidence interval [CI], 1.2 to 10.8; P = .020), history of grade II-IV acute GVHD (OR, 4.6; 95% CI, 1.10 to 18.86; P = .036) and concurrent IST (OR, 5.9; 95% CI, 1.8 to 19.8; P = .004). HCT and CAR-T cell therapy recipients are at an increased risk of moderate-severe COVID-19 pneumonia and higher mortality with SARS-CoV-2 infection. Our findings confirm the need for continuing vigilance with social distancing and masks, vaccination prioritization, close monitoring, and aggressive treatment of HCT/CAR-T therapy recipients.

Outcomes with CD34-Selected Stem Cell Boost for Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Review and Meta-Analysis

Poor graft function (PGF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT) characterized by multilineage cytopenia in the absence of mixed donor chimerism (<95% donor), relapse, or severe graft-versus-host disease (GVHD). We present a systemic review and meta-analysis aimed at assessing the outcomes with CD34-selected stem cell boost (SCB) for PGF in adult allo-HSCT recipients. We screened a total of 1753 records identified from 4 databases (PubMed, Embase, Cochrane, and ClinicalTrials.gov) following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, using the search terms "hematological malignancies," "hematopoietic stem cell transplantation," "CD34 antigen(s)," "graft failure," and "poor graft function," from the date of inception to January 2021. After excluding review, duplicate, and nonrelevant articles, we included 7 studies reporting outcomes following administration of CD34-selected SCB for PGF after allo-HSCT, including hematologic complete response (CR) and overall response rate (ORR), GVHD, and overall survival (OS). Quality evaluation was done using the National Institutes of Health quality assessment tool. Pooled analysis was done using the R 'meta' package, and proportions with 95% confidence intervals (CIs) were computed. The inter-study variance was calculated using the Der Simonian-Laird estimator. We identified 209 patients who received CD34-selected SCB for PGF after allo-HSCT. The median age was 49 years (range, 18 to 69 years), and 61% were men. Primary graft sources included peripheral blood stem cells (72%) and bone marrow (28%). Donor types were matched sibling (37%), matched unrelated (36%), mismatched unrelated (22%), and haploidentical donors (5%). The median time from allo-HSCT to SCB was 138 days (range, 113 to 450 days). The median SCB dose was 3.45 × 10⁶ CD34 cells/kg (range, 3.1 to 4.9 × 10⁶ cells/kg). CR and ORR were 72% (95% CI, 63% to 79%; I² = 26%) and 80% (95% CI, 74% to 85%; I² = 0%), respectively. After a median follow-up of 42 months (range, 30 to 77 months), the actuarial survival rate was 54% (95% CI, 47% to 61%; I² = 0%). OS ranged from 80% at 1 year to 40% at 9 years. The incidences of acute and chronic GVHD after SCB were 17% (95% CI, 13% to 23%; I² = 0%) and 18% (95% CI, 8% to 34%; I² = 76%), respectively. Nonrelapse mortality was reported in 42 patients, with a pooled rate of 27% (95% CI, 17% to 40; I² = 59%), and death due to relapse was reported in 25 patients, with a pooled rate of 17% (95% CI, 11% to 23%; I² = 0%). Our data show that CD34-selected SCB improves outcomes after PGF post allo-HSCT with an acceptable toxicity profile. The literature lacks high-quality randomized evidence, and there remains an unmet need for prospective studies to address the optimal dosing and manipulation of SCB. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Outcomes with COVID-19 in hematopoietic stem cell transplant and cellular therapy patients

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Background: The Coronavirus Disease 2019 (COVID-19) has caused over 25 million infections in the US with over 0.4 million deaths. Hematogenic stem cell transplant (HCT) or cellular therapy (CT) recipients have a high risk of mortality with COVID-19 due to profound immune dysregulation. We aimed to assess the outcomes with COVID-19 in HCT/CT recipients. Methods: A single-center prospective study was conducted, including all (n=40) adult HCT/CT patients who were diagnosed with COVID-19 at the University of Kansas from Apr 2020 to Jan 2021. Baseline and disease-related characteristics were ascertained from medical records. Data were analyzed using SPSS version 21 (SPSS Inc, Chicago, IL). Bivariate analyses, using chi-square and t-test, and logistic regression analyses were conducted. Results: The study included 40 COVID-19 patients (72.5% Oct 2020-Jan 2021), including allogeneic HCT (n=25), autologous HCT (n=13) and CAR-T CT (n=2) with median time since HCT/CT of 12.4 (1-201.9), 37.2 (0.4-118.7), and 3.8 (2.8-4.8) months. Seventy percent were Caucasians and 17.5 were Hispanics. Primary hematologic malignancy was myeloid (37.5%), lymphoid (35%) or plasma cell disorder (27.5%). Myeloablative conditioning was performed in 65% of patients. Donors were autologous (37.5%), matched sibling (17.5%), matched unrelated (22.5%) and haploidentical (22.5%). COVID-19 was mild (42.5%), moderate (42.5%) or severe (15%). Clinical findings included pneumonia (62.5%), hypoxia (25%) and ICU admission (17.5%) while therapies included remdesivir (47.5%), convalescent plasma (40%), dexamethasone (25%) and monoclonal antibodies (17.5%). Concurrent cancer treatment, other infections and active GVHD were reported in 25% (all myeloma), 20% and 32.5% of patients. After a median follow-up of 74 days (7-269), the mortality rate was 12.5% in all patients and 20% in allo-HCT patients. Significant predictors of COVID-19 severity included allogeneic HCT, concurrent immune suppression and elevated inflammatory markers. (Table). Conclusions: Hematopoietic stem cell transplant recipients have an increased risk of mortality with COVID-19. Our findings confirm the need for vaccination prioritization, close monitoring, and aggressive treatment in HCT/CT patients.[Table: see text]

Outcomes with venetoclax in myelodysplastic syndromes: A systematic review

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Background: Myelodysplastic syndromes (MDS) are clonal hemopoietic disorders causing cytopenia(s) and increased risk of transformation to acute myeloid leukemia (AML). Venetoclax is a B-cell lymphoma-2 (BCL-2) inhibitor that induces apoptosis in malignant cells. The FDA has approved venetoclax for the treatment of newly diagnosed adult AML patients unfit for intensive chemotherapy and its utility in MDS is being explored. We present a systematic review aimed to evaluate outcomes with venetoclax in MDS patients. Methods: We performed a literature search on 3 databases (Pubmed, Cochrane, and Clinicaltrials.gov) following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We screened 62 studies using the Mesh terms ‘myelodysplastic syndrome’ and ‘venetoclax’. After excluding review, duplicate and non-relevant articles, 8 studies were included in the analysis. Quality evaluation was done using the NIH quality assessment tool. Pooled analysis was done using the ‘meta’ package (Schwarzer et al, R programming language) and proportions with 95% confidence intervals (CI) were computed. The Inter-study heterogeneity among the studies was assessed using the Q statistic proposed by Cochrane and the I2 index introduced by Higgins and Thompson. Results: We identified 313 patients from 8 studies (1 prospective, 3 retrospective, 2 ex-vivo, 2 clinical trials). Venetoclax was used in combination with hypomethylating agents (HMA) in 6 studies and with other agents in 2 studies. Most patients were pre-treated. Complete response (CR) with or without hematological recovery (CRi) was reported in 45% of patients (95% CI 0.26-0.66, I2= 90%, n = 292). Stable disease (SD) was seen in 18% patients (95% CI 0.08-0.37, I2= 85%, n = 223). Overall response rate (ORR) was 51% (95% CI 0.31-0.70, I2= 89%, n = 122). Hematopoietic stem cell transplant (HCT) was performed in 22% patients (95% CI 0.09-0.44, I2= 75%, n = 122). Twenty percent patients (95% CI 0.15-0.28, I2= 0%, n = 149) died. Common adverse events seen with venetoclax were cytopenias, gastrointestinal side effects and infections, often requiring drug interruption or dose. Conclusions: Despite heterogeneity of available literature, venetoclax seems to be a promising agent in treatment of MDS patients. Prospective clinical trial data is needed to ascertain safety and efficacy of venetoclax in MDS and impact on overall survival, in particular, in patients proceeding to HCT.[Table: see text]

Gender disparities in National Institute of Health funding for hematologic malignancies, hematopoietic stem cell transplantation, and cellular therapeutics

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Background: Gender inequality in research funding has been studied extensively; however, the literature lacks evidence in Hematology. We investigated trends in National Institutes of Health (NIH) funding for hematologic malignancies (HM), hematopoietic stem cell transplantation (HSCT), and cellular therapeutics (CT). Methods: The data on Hematology funding was retrieved from NIH Research Portfolio Online Reporting Tools (RePORT) Categorical Spending for fiscal years 2018 and 2019. A total of 6351 entries were reported. Only grants (n=1834) that were related to HM, HSCT, and CT were included. After excluding non-relevant, 975 principal investigators (PIs) were included in the analysis. Additional data regarding PIs was ascertained from the Scopus database, LinkedIn, Doximity, and departmental websites, including the number of publications, number of years of active research, H-index, highest degree, gender, and institution. Data were analyzed using SPSS version 21. Bivariate analyses, using chi-square and t-test, and linear regression analyses were performed. Results: In 2018 and 2019, 1834 grants totaling $799.4 million were awarded by the NIH for malignant hematology research (men 1301, 71% vs women 533, 29%). Of 975 PIs, 680 (70%) were men and 295 (30%) were women. Table highlights gender disparities in NIH funding and associated factors. Most of the grant recipients were Ph.D. or M.D./Ph.D. About 70% of total funding was awarded to male PIs. There were no gender differences in the mean number of grants and mean grant amount. Women had significantly lower years of active research and academic productivity. Conclusions: Although the gender gap in academic hematology has decreased in recent years, the latest trend suggests significant gender inequality in NIH funding for malignant hematology, transplantation, and cellular therapy.[Table: see text]

Outcomes with CD34 stem cell boost for poor graft function after allogeneic hematopoietic stem cell transplantation for hematologic malignancies: A systemic review and meta-analysis

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Background: Poor graft function (PGF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HCT) characterized by severe multilineage cytopenia in the absence of mixed donor chimerism, relapse, or severe graft-vs-host disease (GVHD). We present a systemic review and meta-analysis aimed to assess the outcomes with stem cell boost (SCB) for PGF in adult allo-HCT patients. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, 752 articles were screened from 4 databases (PubMed, Embase, Cochrane, and Clinical trials.gov) using MeSH terms and keywords for “hematological malignancies”, “hematopoietic stem cell transplantation”, “CD34 antigen(s)” and “treatment outcome(s)” from the date of inception to Jan 2021. After excluding review, duplicate and non-relevant articles, we included 8 studies (1 prospective, 7 retrospective) reporting hematologic complete/overall response rate (CR/ORR), GVHD and overall survival (OS) after SCB for PGF after Allo-HSCT. Quality evaluation was done using the NIH quality assessment tool. Pooled analysis was done using the ‘meta’ package (Schwarzer et al, R programming language) and proportions with 95% confidence intervals (CI) were computed. Inter-study variance was calculated using Der Simonian-Laird Estimator. Results: We identified 217 patients who received SCB for PGF after allo-HCT. Median age, time since transplant and SCB dose were 48 (37-54) years, 133 (113-450) days and 3.43 (1.7-4.9) million CD34 cells/kg respectively. CR and ORR were 71% (95%CI 0.63-0.77, I216%) and 80% (95%CI 0.74-0.85, I20%) respectively. After median follow up of 41.5 (5-77) months, actuarial survival rate (ASR) was 54% (95%CI 0.48-0.61, I20%). OS was reported from 80% (1y) to 40% (9y) Acute and chronic GVHD incidence after SCB was 17% (95% CI 0.12-0.23, I2=0%) and 17% (95% CI 0.08-0.32, I2=72%, n=197) respectively, and 25% (95% CI 0.14-0.39, I2=63%, n=163) deaths were due to relapse (Table). Conclusions: CD34 SCB improves outcomes after PGF after allo-HSCT with acceptable toxicity profile. However, current literature lacks high-quality randomized evidence and there remains an unmet need for prospective studies to address optimal dosing and manipulation of SCB. Outcomes with SCB for PGF after allo-HCT (n=217).[Table: see text]

Outcomes with COVID-19 in patients with hematopoietic stem cell transplant and cellular therapy: A systemic review and meta-analysis

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Background: Coronavirus Disease 2019 (COVID-19) was declared a pandemic on March 11, 2020. COVID-19 has caused over 100 million infections and over 2 million deaths globally. Patients who have received a hematogenic stem cell transplant or cellular therapy (HCT) have a high risk of mortality and morbidity with COVID-19 due to severe immune dysregulation. We conducted a systematic review and meta-analysis aimed to evaluate the outcomes of COVID-19 in HCT patients. Methods: A literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines (PRISMA) guidelines was performed on 3 databases (PubMed, Cochrane, and Clinical trials.gov) from the date of inception to Jan 2021. MeSH terms included ‘hematological malignancies’, ‘hematopoietic stem cell transplantation’, ‘SARS-CoV-2’, and ‘COVID 19’. We screened 99 articles and 6 studies (4 retrospective studies, 2 prospective) were included after excluding review, duplicate, and non-relevant articles. Quality evaluation was done using the NIH quality assessment tool. The Inter-study heterogeneity among the studies was assessed using the Q statistic proposed by Cochrane and the I2 index introduced by Higgins and Thompson. Pooled analysis was done using the ‘metaXL’, and the random effects model was used to estimate the pooled prevalence with 95% CI. Results: Of 1619 patients in 6studies, 646 HCT patients were analyzed (Table ). The median age of patients was 63 years and 59% were males. Median days since HCT for autologous (auto) HCT and allogeneic (allo) HCT patients were 690 and 450 days respectively. The average follow-up duration after COVID-19 was 24 days. COVID-19 mortality in HCT patients was 20% (95%CI 0.17 to 0.23, I2=0). Roedl et al (n=6) reported a mortality of 83% and was excluded from the pooled analysis. The mortality rate was 19% (95% CI 0.15 to 0.24, I2=0%) in auto HCT patients and 21% (95% CI 0.17 to 0.25, I2=0%) in allo HCT patients. Conclusions: The HCT patients are at significant risk of increased mortality and morbidity due to COVID-19. There is a need to prioritize HCT patients for COVID-19 vaccination, close surveillance, and aggressive management.[Table: see text]

Outcomes with preemptive donor lymphocyte infusions after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia and myelodysplastic syndromes: A systematic review and meta-analysis

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Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) but relapse and graft versus host disease (GVHD) remain the most common challenges. Donor lymphocyte infusion (DLI) is the infusion in which lymphocytes from the original stem cell donor are infused, after the transplant, to augment an anti-tumor response or to ensure that the donor stem cells remain engrafted. In this systematic review and meta-analysis, we focused at outcomes of preemptive DLI in AML and MDS. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines (PRISMA) PubMed, CINAHL, Cochrane, and Clinical trials.gov were searched. We included 8 out of 214 articles, excluding duplicates and non-relevant articles. The quality of the included studies was evaluated using NIH quality assessment tool. Proportions along with 95% Confidence Interval (CI) were extracted to compute pooled analysis using the ‘meta’ package by Schwarzer et al. in the R programming language (version 4.16-2) to report the efficacy of preemptive DLI. We pooled the experimental arms results of the included trials using the inverse variance method and logit transformation. Between studies, the variance was calculated using Der Simonian-Laird Estimator. Results: We identified 222 patients who received preemptive DLI. Median age, time since transplant and DLI dose were 48 (32-58) years, 82 (7-160) days and 1.4 million cells/kg respectively. CR and PR were 43% (95%CI 0.14-0.78, I293%, n= 127) and 61% (95%CI 0.40-0.78, I262%, n= 81) respectively. After median follow up of 46 months, non-relapsed mortality (NRM) was 52% (95%CI 0.38-0.65, I249%, n = 121). OS was reported 72% (95%CI 0.62-0.80, I20%, n= 100). Acute and chronic GVHD incidence after DLI was 20% (95% CI 0.13-0.29, I24%, n= 105) and 25% (95% CI 0.08-0.56, I2=79%, n=101) respectively (Table). Conclusions: Preemptive DLI significantly improves OS with a low incidence of acute and chronic GVHD. However, NRM was seen in more than half of all the patients and prospective studies are needed to evaluate safety of preemptive DLI. Outcomes with preemptive DLI (n= 222).[Table: see text]

Preclinical Evaluation of Gilteritinib on NPM1-ALK-Driven Anaplastic Large Cell Lymphoma Cells

Anaplastic large cell lymphoma (ALCL) is an aggressive type of non-Hodgkin lymphoma. More than three-fourths of anaplastic lymphoma kinase (ALK)-positive ALCL cases express the nucleophosmin 1 (NPM1)-ALK fusion gene as a result of t(2;5) chromosomal translocation. The homodimerization of NPM1-ALK fusion protein mediates constitutive activation of the chimeric tyrosine kinase activity and downstream signaling pathways responsible for lymphoma cell proliferation and survival. Gilteritinib is a tyrosine kinase inhibitor recently approved by the FDA for the treatment of FMS-like tyrosine kinase mutation-positive acute myeloid leukemia. In this study, we demonstrate for the first time gilteritinib-mediated growth inhibitory effects on NPM1-ALK-driven ALCL cells. We utilized a total of five ALCL model cell lines, including both human and murine. Gilteritinib treatment inhibits NPM1-ALK fusion kinase phosphorylation and downstream signaling, resulting in induced apoptosis. Gilteritinib-mediated apoptosis was associated with caspase 3/9, PARP cleavage, the increased expression of proapoptotic protein BAD, and decreased expression of antiapoptotic proteins, survivin and MCL-1. We also found downregulation of fusion kinase activity resulted in decreased c-Myc protein levels. Furthermore, cell-cycle analysis indicated gilteritinib induced G₀-G₁-phase cell-cycle arrest and reduced CD30 expression. In summary, our preclinical studies explored the novel therapeutic potential of gilteritinib in the treatment of ALCL cells expressing NPM1-ALK and potentially in other ALK or ALK fusion-driven hematologic or solid malignancies. IMPLICATIONS: Our preclinical results explore the use of gilteritinib for the treatment of NPM1-ALK-driven ALCL cells and pave a path for developing future clinical trials. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/5/913/F1.large.jpg.

A novel tetrazole analogue of resveratrol is a potent anticancer agent

A series of novel tetrazole analogues of resveratrol were synthesized and evaluated for their anti-leukemic activity against an extensive panel of human cancer cell lines and against the MV4-11 AML cell line. These molecules were designed as drug-like derivatives of the resveratrol analogue DMU-212 and its cyano derivatives. Four compounds 8g, 8h, 10a and 10b exhibited LD₅₀ values of 4.60 µM, 0.02 µM, 1.46 µM, and 1.08 µM, respectively, against MV4-11 leukemia cells. The most potent compounds, 8h and 10b, were also found to be active against an extensive panel of human hematological and solid tumor cell lines; compound 8h was the most potent compound with GI₅₀ values <10 nM against more than 90% of the human cancer cell lines in the 60-cell panel. Analogues 8g, 8h, 10a and 10b were also tested for their ability to inhibit the polymerization of tubulin, and compound 8h was found to be the most potent analogue. Molecular modeling studies demonstrated that 8h binds to the colchicine binding site on tubulin. Thus, compound 8h is considered to be a lead druglike molecule from this tetrazole series of compounds.

Targeted Therapy for EBV-Associated B-cell Neoplasms

Epstein-Barr virus (EBV) is directly implicated in several B-cell lymphoid malignancies. EBV-associated lymphomas are characterized by prominent activation of the NF-κB pathway and targeting this pathway establishes a rationale for a therapeutic approach. The ubiquitin/proteasome signaling plays an essential role in the regulation of the NF-κB pathway. Ixazomib is an FDA-approved, orally bioavailable proteasome inhibitor. Here we report the first preclinical evaluation of ixazomib-mediated growth-inhibitory effects on EBV-infected B-lymphoblastoid cell lines Raji and Daudi. Ixazomib induced apoptosis in these cell lines in a dose-dependent manner. Cell-cycle analysis demonstrated ixazomib treatment induced cell-cycle arrest at the G₂-M phase with a concomitant decrease in G₀-G₁ and S phases. The results further revealed an increase in p53, p21, and p27 levels and a decrease in survivin and c-Myc protein levels. Mechanistically, ixazomib treatment resulted in the accumulation of polyubiquitinated proteins, including phosphorylated IκBα with a significant reduction of p65 subunit nuclear translocation. Altogether, our preclinical data support the rationale for in vivo testing of ixazomib in EBV-associated B-cell neoplasms. IMPLICATIONS: This preclinical study supports the use of oral proteasome inhibitor ixazomib for targeting NF-κB signaling in the treatment of EBV-associated B-cell neoplasms.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/17/4/839/F1.large.jpg.

Silver carbene complexes: An emerging class of anticancer agents

Cancer is a major global health problem with large therapeutic challenges. Although substantial progress has been made in cancer therapy, there still remains a need to develop novel and effective treatment strategies to treat several relapsed and refractory cancers. Recently, there has been growing demand for considering organometallics as antineoplastic agents. This review is focused on a group of organometallics, silver N-heterocyclic carbene complexes (SCCs) and their anticancer efficacy in targeting multiple pathways in various in vitro cancer model systems. However, the precise molecular mechanism of SCCs anticancer properties remains unclear. Here, we discuss the SCCs chemistry, potential molecular targets, possible molecular mechanism of action, and their application in cancer therapies.

Leukemogenic nucleophosmin mutation disrupts the transcription factor hub that regulates granulomonocytic fates

Nucleophosmin (NPM1) is among the most frequently mutated genes in acute myeloid leukemia (AML). It is not known, however, how the resulting oncoprotein mutant NPM1 is leukemogenic. To reveal the cellular machinery in which NPM1 participates in myeloid cells, we analyzed the endogenous NPM1 protein interactome by mass spectrometry and discovered abundant amounts of the master transcription factor driver of monocyte lineage differentiation PU.1 (also known as SPI1). Mutant NPM1, which aberrantly accumulates in cytoplasm, dislocated PU.1 into cytoplasm with it. CEBPA and RUNX1, the master transcription factors that collaborate with PU.1 to activate granulomonocytic lineage fates, remained nuclear; but without PU.1, their coregulator interactions were toggled from coactivators to corepressors, repressing instead of activating more than 500 granulocyte and monocyte terminal differentiation genes. An inhibitor of nuclear export, selinexor, by locking mutant NPM1/PU.1 in the nucleus, activated terminal monocytic fates. Direct depletion of the corepressor DNA methyltransferase 1 (DNMT1) from the CEBPA/RUNX1 protein interactome using the clinical drug decitabine activated terminal granulocytic fates. Together, these noncytotoxic treatments extended survival by more than 160 days versus vehicle in a patient-derived xenotransplant model of NPM1/FLT3-mutated AML. In sum, mutant NPM1 represses monocyte and granulocyte terminal differentiation by disrupting PU.1/CEBPA/RUNX1 collaboration, a transforming action that can be reversed by pharmacodynamically directed dosing of clinical small molecules.

1-Benzyl-2-methyl-3-indolylmethylene barbituric acid derivatives: Anti-cancer agents that target nucleophosmin 1 (NPM1)

In the present study, we have designed and synthesized a series of 1-benzyl-2-methyl-3-indolylmethylene barbituric acid analogs (7a-7h) and 1-benzyl-2-methyl-3-indolylmethylene thiobarbituric acid analogs (7 i-7 l) as nucleophosmin 1 (NPM1) inhibitors and have evaluated them for their anti-cancer activity against a panel of 60 different human cancer cell lines. Among these analogs 7 i, 7 j, and 7 k demonstrated potent growth inhibitory effects in various cancer cell types with GI50 values <2 μM. Compound 7 k exhibited growth inhibitory effects on a sub-panel of six leukemia cell lines with GI50 values in the range 0.22-0.35 μM. Analog 7 i also exhibited GI50 values <0.35 μM against three of the leukemia cell lines in the sub-panel. Analogs 7 i, 7 j, 7 k and 7 l were also evaluated against the mutant NPM1 expressing OCI-AML3 cell line and compounds 7 k and 7 l were found to cause dose-dependent apoptosis (AP50 = 1.75 μM and 3.3 μM, respectively). Compound 7k also exhibited potent growth inhibition against a wide variety of solid tumor cell lines: that is, A498 renal cancer (GI50 = 0.19 μM), HOP-92 and NCI-H522 lung cancer (GI50 = 0.25 μM), COLO 205 and HCT-116 colon cancer (GI50 = 0.20 and 0.26 μM, respectively), CNS cancer SF-539 (GI50 = 0.22 μM), melanoma MDA-MB-435 (GI50 = 0.22 μM), and breast cancer HS 578T (GI50 = 0.22 μM) cell lines. Molecular docking studies suggest that compounds 7 k and 7 l exert their anti-leukemic activity by binding to a pocket in the central channel of the NPM1 pentameric structure. These results indicate that the small molecule inhibitors 7 i, 7 j, 7 k, and 7 l could be potentially developed into anti-NPM1 drugs for the treatment of a variety of hematologic malignancies and solid tumors.

Abstract 776: Pre-clinical evaluation of ceritinib in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is an aggressive CD30+ T-Cell lymphoma that accounts for 2-8% and 10-15% non-Hodgkin lymphomas in adults and children, respectively. The currently used standard therapy for anaplastic lymphoma kinase (ALK, a member of insulin receptor superfamily) positive ALCL has limited effectiveness, resulting in a substantial percentage of cases with poor outcome, either failing to enter remission or relapsing within a few months after starting the treatment. Thus, there is a clear unmet clinical need for developing novel, effective and safer therapeutic strategies for ALCL. Nucleophosmin 1 (NPM1) is a nucleolar phosphoprotein, which functions as a molecular chaperone for proteins and nucleic acids. Approximately 50% of ALCL cases are positive for the NPM-ALK fusion chimera generated by the t(2;5) chromosomal translocation. The oligomerization domain of NPM1 in the fusion protein NPM-ALK, mediates the ligand-independent dimerization of chimeric protein, which results in constitutive activation of the chimeric tyrosine kinase activity leading to downstream signaling pathways responsible for the oncogenicity. Ceritinib is a second generation FDA approved ALK inhibitor for the treatment of ALK-positive metastatic non-small cell lung cancer. Here we report the first preclinical evaluation of ceritinib growth inhibitory effects on ALK-positive ALCL cells. The NPM-ALK expressing ALCL model cell line SUDHL-1 used in our studies. Treatment with ceritinib significantly induced apoptosis dose dependently (10-50nM) in ALCL cells associated with poly (ADP-ribose) polymerase cleavage. Mechanistically, ceritinib blocked phosphorylation of ALK and its downstream signaling effectors STAT3, AKT and ERK1/2. Cell cycle analysis by flow cytometry showed that ceritinib induced G0/G1 arrest with concomitant decrease in the percentage of cells in S and G2/M phases which was associated with decreased cyclin D1 and increased p21 expression. ALCL is also characterized by strong expression of the cytokine receptor CD30 (a member of the TNF receptor family). CD30 stimulation leads to NF-kB activation and the induction of anti-apoptotic mechanisms. In response to ceritinib treatment, flow cytometry data showed that reduced CD30 expression in a dose dependent manner. Altogether, these pre-clinical results demonstrate that ceritinib induces apoptosis in ALCL cells by inhibiting ALK downstream signaling cascade and support the rational for in vivo testing of ceritinib for the treatment of ALK positive lymphomas.

Citation Format: Siddhartha Ganguly, Sudhakiranmayi Kuravi, Satyanarayana Alleboina, Brandon Weckbaugh, Deepti Satelli, Jensen Roy, Scott Weir, Joseph McGuirk, Ramesh Balusu. Pre-clinical evaluation of ceritinib in anaplastic large cell lymphoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 776. doi:10.1158/1538-7445.AM2015-776

Abstract 4905: Targeting NPM1 for the radiosensitization of NSCLC

Lung cancer is a global scourge. In 2008 alone there were more than 1.25 million deaths from this disease worldwide. Eighty five percent of lung cancers are classified as non-small cell lung cancer (NSCLC) and for those NSCLC patients who present with locally advanced stage IIIA/B disease the standard of care is chemo/radiation therapy. Yet even with this approach the median duration of survival is only 17 months. Thus, there is an urgent need for the development of new strategies that improve therapeutic outcomes. We addressed this challenge by employing a forward chemical genetics screen designed to identify compounds that could be used to exploit DNA repair pathways in tumor cells burdened with oncogenesis-mediated replication stress. Using this approach we identified YTR107, a substituted 5-((N-benzyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H) trione, that amplifies replication stress and inhibits repair of DNA DSBs. Using biochemical approaches we identified NPM1 as a potential target and found that YTR107 impairs NPM1 oligomerization, a requirement for NPM1's biochemical activity. However, direct genetic evidence demonstrating that the specific targeting of NPM1 is a radiosensitizing event remains to be established. Therefore we employed a defined genetic model consisting of NPM1 null and wild type mouse embryo fibroblasts (MEFs). We found that proliferating NPM1-null mouse embryo fibroblasts (MEFs), but not wild type MEFs, are burdened with high levels of γH2AX foci, a characteristic of replication stress. NPM1-null MEFs exhibit a defect in Rad51-mediated repair of DNA DSBs that increases radiation sensitivity. Use of this model allowed us to demonstrate that YTR107-mediated radiosensitization requires NPM1. Because the DNA damage response pathway is continuously activated in NSCLC in response to constant replication stress, and with the knowledge that NPM1 expression minimizes such stress, we hypothesized that NSCLC tumors might require significant expression of NPM1. This hypothesis was validated by analyzing a NSCLC tumor microarray. We then showed that YTR107-mediated targeting of NPM1 is a radiosensitizing event in 6 NSCLC cell lines and in a syngeneic tumor model. We also found that YTR107 is well tolerated in mice, does not produce overt toxicity, and does not potentiate radiation-mediated pulmonary fibrosis. These data suggest that NPM1 represents a potential molecular target for radiosensitization of NSCLC.

Citation Format: Konjeti R. Sekhar, Mouadh Benamar, Amudhan Venkateswaran, Narsimha R. Penthala, Peter A. Crooks, Stephen R. Hann, Ling Geng, Ramesh Balusu, Tarek Abbas, Michael L. Freeman. Targeting NPM1 for the radiosensitization of NSCLC. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4905. doi:10.1158/1538-7445.AM2014-4905

Abstract 2034: Co-treatment with NPM1 antagonist and FLT3 inhibitor or pan-histone deacetylase inhibitor exerts superior efficacy against cultured and primary human AML cells co-expressing mutant NPM1 and FLT3-ITD

In approximately 50% of the normal-karyotype (NK) AML, a mutant (mt) NPM1 is localized in the cytoplasm (NPM1c+), which is pathogenetic for AML. Co-expression of FLT3-ITD with mtNPM1 results in poor outcome in AML. We have previously reported that in the cultured (OCI-AML3) cells carrying mtNPM1, shRNA-mediated knockdown of both the wild-type and mtNPM1 induced p53, p21, p27 and CEBPα, while attenuating the levels of HOXA9 and Meis1. This was associated with the morphologic features of myeloid differentiation, apoptosis, as well as a marked inhibition of the colony growth of OCI-AML3 cells (p&lt;0.01). Additionally, knockdown of NPM1 sensitized OCI-AML3 cells to all-trans retinoic acid (ATRA) (0.25 to 2.0 μM)-induced differentiation and apoptosis (p&lt;0.01). Findings of our present studies demonstrate that, as compared to the shRNA-mediated knockdown of total NPM1 (wild-type and mtNPM1), selective knockdown of mtNPM1 alone induced less differentiation and apoptosis of OCI-AML3 cells, as well as caused less inhibition of the leukemogenic potential of OCI-AML3 cells in NOD/SCID mice. The small molecule inhibitor NSC348884 is known to disrupt the oligomerization of wild-type and mtNPM1. NSC348884 dose-dependently (1.0 to 3.0 μM) induced apoptosis and sensitized OCI-AML3 and primary AML cells expressing NPM1c+ to ATRA-induced apoptosis (p&lt;0.01). Patient-derived primary AML cells co-expressing mtNPM1 and FLT3-ITD, as well as OCI-AML3 cells transfected with FLT3-ITD lentivirus (OCI-AML3/FI cells) that co-expressed NPM1c+ and FLT3-ITD were relatively resistant to NSC348884 and/or ATRA. Notably, combination with NSC348884 (2.0-5.0 μM) and the FLT3 antagonists ponatinib (0.5 to 1.0 μM), AC220 (0.2 to 1.0 μM) or midostaurin (100 to 500 nM) induced more apoptosis than either agent alone against OCI-AML3/FI and primary AML cells co-expressing mtNPM1 and FLT3-ITD (p&lt;0.01). Importantly, treatment with the clinically achievable levels of pan-histone deacetylase inhibitor panobinostat (PS, 10 to 50 nM) depleted NPM1 levels and induced differentiation of OCI-AML3, OCI-AML3/FI, and primary AML cells co-expressing mtNPM1 and FLT3-ITD (40 to 70%). Additionally, as compared to treatment with each agent alone, co-treatment with NSC348884 and PS induced significantly more apoptosis in these cells (p&lt;0.01). This was associated with reduction in the levels of p-FLT3, p-AKT, p-STAT5 and NPM1, as well as induction of p53 and p21 levels. Therefore, co-treatment with an NPM1 antagonist and PS or FLT3 inhibitor is highly active against AML cells co-expressing mtNPM1 and FLT3-ITD. These findings support the rationale for in vivo testing of these combination therapies against AML with co-expression of mtNPM1 and FLT3-ITD.

Citation Format: Warren Fiskus, Ramesh Balusu, Karissa Peth, Stacey Hembruff, Sunil Abhyankar, Joseph McGuirk, Kapil N. Bhalla. Co-treatment with NPM1 antagonist and FLT3 inhibitor or pan-histone deacetylase inhibitor exerts superior efficacy against cultured and primary human AML cells co-expressing mutant NPM1 and FLT3-ITD. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2034. doi:10.1158/1538-7445.AM2013-2034

Superior efficacy of a combined epigenetic therapy against human mantle cell lymphoma cells

PURPOSE

A deregulated epigenome contributes to the transformed phenotype of mantle cell lymphoma (MCL). This involves activity of the polycomb repressive complex (PRC) 2, containing three core proteins, EZH2, SUZ12, and EED, in which the SET domain of EZH2 mediates the histone methyltransferase activity. We determined the effects of 3-deazaneplanocin A (DZNep), an S-adenosylhomocysteine hydrolase inhibitor, and/or pan-histone deacetylase inhibitor panobinostat (PS) on cultured and primary MCL cells.

EXPERIMENTAL DESIGN

Following treatment with DZNep and/or PS, apoptosis and the levels and activity of EZH2 and PRC2 proteins in cultured and primary MCL cells were determined.

RESULTS

Treatment with DZNep depleted EZH2, SUZ12, and 3MeK27H3 in the cultured human MCL cells. DZNep also increased expression of p21, p27, and FBXO32, whereas it depleted Cyclin D1 and Cyclin E1 levels in MCL cells. In addition, DZNep treatment induced cell-cycle arrest and apoptosis in cultured and primary MCL cells. Furthermore, as compared with treatment with each agent alone, cotreatment with DZNep and PS caused greater depletion of EZH2, SUZ12, 3MeK27H3, and Cyclin D1 levels, whereas it induced greater expression of FBXO32, p16, p21, and p27. Combined treatment with DZNep and PS synergistically induced apoptosis of cultured and primary MCL cells while relatively sparing normal CD34 + cells. Cotreatment with DZNep and PS also caused significantly greater inhibition of tumor growth of JeKo-1 xenografts in NOD/SCID mice.

CONCLUSIONS

These preclinical in vitro and in vivo findings show that cotreatment with DZNep and PS is an active combined epigenetic therapy worthy of further in vivo testing against MCL.

Combined targeting of LSD1 (KDM1A) and histone deacetylases exerts superior efficacy against human AML

10549

Background: LSD1 (KDM1A) is FAD-dependent histone H3K4Me2 demethylase. Inhibition of LSD1 increases H3K4Me3-a permissive mark for gene expression, and inhibits growth of pluripotent cancer cells. We have previously noted that treatment with the histone deacetylase (HDAC) inhibitor panobinostat (PS) depletes EZH2 (the catalytic subunit of the polycomb repressive complex 2, PRC2) and disrupts its interaction with the other PRC2 proteins, attenuates LSD1, and de-represses growth inhibitory and pro-apoptosis genes. Methods: In the present studies, we determined the chromatin effects and the pre-clinical in vitro and in vivo anti-AML activity of the novel, non-monoamine oxidase, reversible inhibitor of LSD1, HCI2509 (100 to 500 nM), alone and in combination with PS, utilizing cultured (OCI-AML3 and HL-60) and primary human AML blast progenitor cells. Results: Treatment with HCI2509 dose-dependently increased the levels of H3K4Me3, p16, p27, and CEBPα in cultured AML cells. This correlated with inhibition of cell growth and induction of morphologic differentiation in AML cells. Exposure to HCI2509 disrupted the binding of LSD1 with the co-repressor CoREST and HDAC1. Treatment with PS (10 to 50 nM) dose-dependently depleted not only LSD1 but also EZH2, SUZ12 and BMI1 in AML cells. Co-treatment with PS enhanced the chromatin modifying effects of HCI2509. The combination also synergistically induced loss of viability of cultured and primary AML cells (combination indices, CI <1.0). Following tail vein infusion and establishment of AML by OCI-AML3 cells in NOD-SCID mice, treatment with HCI2509 (25 mg/kg, b.i.w, IP, for 3 weeks) improved survival, as compared to the control mice (p <0.001). HCI2509 treatment (15 mg/kg IP) also dramatically improved survival of NSG mice with established human AML following tail-vein injection of primary AML blasts expressing FLT3-ITD. Survival was further improved upon co-treatment with HCI2509 and PS (5 mg/kg IP, MWF). Mice did not experience any toxicity or weight loss. Conclusions: Combined epigenetic therapy with HCI2509 and PS exerts superior pre-clinical activity, warranting further in vivo development and testing of HCI2509 against human AML.

Abstract 4698: Inhibition of histone deacetylase (HDAC) 3 induces hyperacetylation and inhibition of nuclear heat shock protein (hsp) 90 leading to depletion of ATR and CHK1 with sensitization to DNA damage in breast and cervical cancer cells

We have recently reported that in addition to checkpoint kinase 1 (CHK1), ataxia-telangiectasia mutated and Rad3- related (ATR) is chaperoned by hsp90. Treatment of breast and cervical cancer cells with hsp90 inhibitor induces proteasomal degradation and depletion of ATR and CHK1. This results in impairment of the DNA damage response (DDR) and causes sensitization to α-irradiation and replication stress due to hydroxyurea (Mol Cancer Ther 10:1194, 3011). In the present studies, we determined that treatment with pan-histone deacetylase (HDAC) inhibitor panobinostat (20 to 50 nM) or vorinostat (0.5 to 2 μM) induced polyubiquitylation and depletion of ATR and CHK1. Co-treatment with bortezomib, a proteasome inhibitor, restored PS-mediated depletion of ATR and CHK1. Notably, treatment with panobinostat induced hyperacetylation of both nuclear and cytoplasmic hsp90. This inhibited the chaperone association of nuclear hsp90 with ATR and CHK1, thereby promoting their degradation. PS treatment induced γ-H2AX levels, which were inhibited by co-treatment with N-acetylcysteine, suggesting that PS-induced ROS is involved in DNA damage. Moreover, PS treatment further increased α-irradiation induced DNA damage and its repair, characterized by the increase in α-irradiation-induced comet tail moment and the lack of DNA repair-mediated attenuation of the comet tail moment. To determine which class I HDAC is involved in deacetylation of nuclear hsp90, we individually knocked down (KD) HDAC 1, 2 and 3, by utilizing specific shRNA, and determined the effect on nuclear hsp90 hyperacetylation and the levels of ATR and CHK1. Our findings show that HDAC3 binds to hsp90 and KD of HDAC3, but not of HDAC1 or 2, caused hyperacetylation of nuclear hsp90 and depletion of ATR and CHK1. This was also observed in HDAC3 null mouse embryonic fibroblasts (MEFs). Ectopic overexpression of HDAC3 inhibited nuclear hsp90 acetylation in transformed cells. These findings demonstrate that HDAC3 is the nuclear hsp90 lysine deacetylase. They also demonstrate that genetic KD of HDAC3, or its inhibition by pan-HDAC inhibitors, induces hyperacetylation of hsp90, mediates loss of hsp90 chaperone association and depletion of ATR and CHK1, abrogates α-irradiation-induced DDR, and results in sensitization of transformed cells to DNA damage due to α-irradiation or replication stress.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4698. doi:1538-7445.AM2012-4698

Abstract 1043: Combined targeting of chromatin modifying enzymes LSD1, histone deacetylases (HDACs) and EZH2 has superior efficacy against human acute myeloid leukemia cells

LSD1 or KDM1A is a FAD-dependent demethylase, with homology to amine oxidases. LSD1 demethylates di- and mono-methylated lysine (K)4 on histone H3, reducing the permissive H3K4Me3 chromatin mark. LSD1 inhibition attenuates growth of pluripotent cancer cells with OCT4 and SOX2 expression. LSD1 complexes with HDAC1/2 and Co-REST, and high LSD1 expression confers poor prognosis in cancers. Previous studies have shown that HDAC inhibitors downregulate LSD1 thru Sp1 inhibition. Inhibition of LSD1 leads to increase in H3K4Me3-a permissive mark for gene expression. HCI2509 is an FAD-binding pocket, non-MAOA and MAOB LSD1 inhibitor. In the present studies, we determined the chromatin-modifying and cytotoxic effects of HCI2509 alone and in combination with the pan-histone deacetylase inhibitor, panobinostat (PS) in cultured (HL-60 and OCI-AML3) and primary human acute myeloid leukemia (AML) cells. Treatment with HCI2509 (100 to 500 nM), dose-dependently increased the levels of H3K4Me2 & Me3, p16 and p27, which was associated with inhibition of cell proliferation as measured by a decrease in Ki-67 expression. Chromatin immunoprecipitation followed by PCR demonstrated that treatment with HCI2509 increased the H3K4Me3 mark on the promoters of KLF4, HMOX1, and CDH1 in AML cells. Treatment with HCI2509 also induced C/EBPα expression and features of morphologic differentiation of cultured and primary AML cells. Treatment with HCI2509 (25 mg/kg B.I.W. via IP injection) significantly improved the survival of NOD/SCID mice bearing OCI-AML3- AML xenografts. We have previously reported that treatment with PS (Novartis Pharma) depleted PRC2 complex proteins EZH2, and SUZ12 but also modestly depleted LSD1 expression in AML cells. Co-treatment with PS enhanced the chromatin modifying effects of HCI2509 on K4 of Histone H3 in AML cells. Co-treatment with HCI2509 and PS synergistically induced apoptosis of the cultured AML cells (combination indices, CI &lt;1.0). This was associated with greater induction of p16, and p27. Co-treatment with HCI2509 and PS also induced significantly greater loss of viability of primary AML cells but not of normal CD34+ cells. We have previously reported that treatment with the S-adenosylhomocysteine hydrolase and EZH2 inhibitor, DZNep, dose-dependently depleted EZH2, and SUZ12 levels in cultured and primary AML cells. Combined treatment with HCI2509 enhanced the apoptosis of AML cells induced by DZNep. Taken together, these findings indicate that combined targeted depletion of the level and activity of LSD1 and HDACs by PS and HCI2509, along with PS-mediated depletion of PRC2 proteins, exerts superior and selective cytotoxic activity against AML cells. These findings also support the in vivo testing of combined epigenetic therapies in the treatment of AML.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1043. doi:1538-7445.AM2012-1043

Abstract 2078: Treatment with auranofin induces oxidative and lethal endoplasmic reticulum (ER) stress exerting single agent activity against mantle cell lymphoma cells

Auranofin (AF) (Ridaura®) is an oral, FDA-approved, lipophilic, gold-containing compound used for the treatment of rheumatoid arthritis. In the present studies, we determined for the first time the lethal activity of AF (100 to 1000 nM) and its underlying mechanism(s) in cultured and primary Mantle Cell Lymphoma (MCL) cells. We demonstrate that treatment with AF in JeKo-1 and Z138C cells induced 2 to 3.5 fold increase in reactive oxygen species (ROS) levels (assessed by flow cytometry), decrease in thioredoxin reductase (TRR) activity (mean reduction of 35-40%) without alteration in the expression of TRR. These findings were associated with induction of nuclear factor erythroid 2-related factor 2 (NRF2) activity marked by substantial increase in heme oxygenase-1 (HMOX1) expression. Microarray analysis revealed that AF treatment significantly upregulated ER stress and oxidative stress inducible genes including that of the ER-stress induced pro-apoptotic transcription factor CHOP (CAAT/enhancer binding protein homologous protein), ATF3 (Activated Transcription Factor 3) and Glutamate-cysteine ligase (GCL), modifier subunit (GCLM), the rate-limiting enzyme in the glutathione (GSH) biosynthesis. Exposure to AF induced significantly more apoptosis in primary MCL cells, as compared to CD19+ normal B cells, CD34+ human cord blood and bone marrow progenitor cells (&lt; 15% apoptosis) (p &lt; 0.01). Based on the observations that AF treatment induced oxidative and ER stress, we determined whether exposure to AF increased the intracellular levels of misfolded and polyubiquitylated proteins, which would disrupt the cytosolic complex consisting of the heat shock protein (hsp) 90, heat shock factor (hsf) 1, histone deacetylase 6 (HDAC6) and p97/VCP, resulting in hyperacetylation and inhibition of the chaperone function of hsp90. Indeed, treatment with AF disrupted the association between hsp90 and HDAC6, HSF1 and p97, resulting in hyperacetylation of hsp90 and depletion of the levels of hsp90 client proteins including HDAC6, AKT and Cyclin D1 in MCL cells. Co-treatment of MCL cells with AF and the proteasome inhibitor carfilzomib (CZ) resulted in synergistic apoptosis in cultured MCL cells and significantly more apoptosis in primary MCL cells, than treatment with each agent alone. Based on the induction of GCLM and anti-oxidant response genes following AF treatment, we tested the anti-MCL activity of the combination of AF and the GCL inhibitor Buthionine sulphoximine (BSO), against MCL cells. Co-treatment with BSO and AF resulted in significantly more apoptosis of MCL cells than treatment with each agent alone. Collectively, our data creates a strong rationale for determining the in vivo activity of AF in patients with MCL as a single agent and in combination with other ER and oxidative stress-inducing agents, especially GCL inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2078. doi:1538-7445.AM2012-2078

Combination of pan-histone deacetylase inhibitor and autophagy inhibitor exerts superior efficacy against triple-negative human breast cancer cells

Histone deacetylase (HDAC) inhibitors (HDI) induce endoplasmic reticulum (ER) stress and apoptosis, while promoting autophagy, which promotes cancer cell survival when apoptosis is compromised. Here, we determined the in vitro and in vivo activity of the combination of the pan-HDI panobinostat and the autophagy inhibitor chloroquine against human estrogen/progesterone receptor and HER2 (triple)-negative breast cancer (TNBC) cells. Treatment of MB-231 and SUM159PT cells with panobinostat disrupted the hsp90/histone deacetylase 6/HSF1/p97 complex, resulting in the upregulation of hsp. This was accompanied by the induction of enhanced autophagic flux as evidenced by increased expression of LC3B-II and the degradation of the autophagic substrate p62. Treatment with panobinostat also induced the accumulation and colocalization of p62 with LC3B-II in cytosolic foci as evidenced by immunofluorescent confocal microscopy. Inhibition of panobinostat-induced autophagic flux by chloroquine markedly induced the accumulation of polyubiquitylated proteins and p62, caused synergistic cell death of MB-231 and SUM159PT cells, and inhibited mammosphere formation in MB-231 cells, compared with treatment with each agent alone. Finally, in mouse mammary fat pad xenografts of MB-231 cells, a tumor size-dependent induction of heat shock response, ER stress and autophagy were observed. Cotreatment with panobinostat and chloroquine resulted in reduced tumor burden and increased the survival of MB-231 breast cancer xenografts. Collectively, our findings show that cotreatment with an autophagy inhibitor and pan-HDI, for example, chloroquine and panobinostat results in accumulation of toxic polyubiquitylated proteins, exerts superior inhibitory effects on TNBC cell growth, and increases the survival of TNBC xenografts.

Heat shock protein 90 inhibitor is synergistic with JAK2 inhibitor and overcomes resistance to JAK2-TKI in human myeloproliferative neoplasm cells

PURPOSE

We determined the activity of hsp90 inhibitor, and/or Janus-activated kinase 2 (JAK2) tyrosine kinase inhibitor (TKI), against JAK2-V617F-expressing cultured mouse (Ba/F3-JAK2-V617F) and human (HEL92.1.7 and UKE-1) or primary human CD34(+) myeloproliferative neoplasm (MPN) cells.

EXPERIMENTAL DESIGN

Following exposure to the hsp90 inhibitor AUY922 and/or JAK2-TKI TG101209, the levels of JAK2-V617F, its downstream signaling proteins, as well as apoptosis were determined.

RESULTS

Treatment with AUY922 induced proteasomal degradation and depletion of JAK2-V617F as well as attenuated the signaling proteins downstream of JAK2-V617F, that is, phospho (p)-STAT5, p-AKT, and p-ERK1/2. AUY922 treatment also induced apoptosis of HEL92.1.7, UKE-1, and Ba/F3-hJAK2-V617F cells. Combined treatment with AUY922 and TG101209 caused greater depletion of the signaling proteins than either agent alone and synergistically induced apoptosis of HEL92.1.7 and UKE-1 cells. Cotreatment with AUY922 and TG101209 also induced significantly more apoptosis of human CD34(+) MPN than normal hematopoietic progenitor cells. As compared with the sensitive controls, JAK2-TKI-resistant HEL/TGR and UKE-1/TGR cells exhibited significantly higher IC(50) values for JAK2-TKI (P < 0.001), which was associated with higher expression of p-JAK2, p-STAT5, p-AKT, and Bcl-xL, but reduced levels of BIM. Unlike the sensitive controls, HEL/TGR and UKE/TGR cells were collaterally sensitive to the hsp90 inhibitors AUY922 and 17-AAG, accompanied by marked reduction in p-JAK2, p-STAT5, p-AKT, and Bcl-xL, with concomitant induction of BIM.

CONCLUSIONS

Findings presented here show that cotreatment with hsp90 inhibitor and JAK2-TKI exerts synergistic activity against cultured and primary MPN cells. In addition, treatment with hsp90 inhibitor may overcome resistance to JAK2-TKI in human MPN cells.

Hsp90 inhibitor-mediated disruption of chaperone association of ATR with hsp90 sensitizes cancer cells to DNA damage

Following DNA damage that results in stalled replication fork, activation of ATR-CHK1 signaling induces the DNA damage response (DDR) in transformed cells. In the present studies on human cervical and breast cancer cells, we determined the effects of hsp90 inhibition on the levels and accumulation of DNA damage/repair-associated proteins following exposure to γ-ionizing radiation (IR; 4 Gy). We show that hsp90 inhibition with 17-allylamino-demehoxygeldanamycin or the novel, nongeldanamycin analogue AUY922 (resorcinylic isoxazole amide; Novartis Pharma) dose-dependently reduced the levels of ATR and CHK1 without affecting ATM levels. AUY922-mediated depletion of ATR and CHK1 was associated with an increase in their polyubiquitylation and decreased binding to hsp90. Cotreatment with bortezomib partially restored AUY922-mediated depletion of ATR and CHK1 levels. Additionally, treatment with AUY922 reduced the accumulation of ATR, p53BP1, and CHK1 but not γ-H2AX to the sites of DNA damage. Following exposure to IR, AUY922 treatment abrogated IR-induced phospho (p)-ATR and p-CHK1 levels, but significantly enhanced γ-H2AX levels. AUY922 treatment also increased IR-induced accumulation of the cells in G(2)-M phase of the cell cycle, inhibited the repair of IR-induced DNA damage, and augmented IR-mediated loss of clonogenic survival. Short hairpin RNA-mediated depletion of ATR also inhibited IR-induced p-ATR and p-CHK1, but increased γ-H2AX levels, sensitizing cancer cells to IR-induced apoptosis and loss of clonogenic survival. These findings indicate that ATR is a bona fide hsp90 client protein and post-IR administration of AUY922, by inhibiting ATR-CHK1-mediated DDR, sensitizes cancer cells to IR.

Abstract 2076: HSF1 inhibition accentuates the lethal activity of proteasome inhibitor in human pancreatic cancer cells

Presence of aneuploidy increases the intracellular levels of misfolded proteins and proteotoxic stress phenotype in cancer cells, which is exploited and further accentuated by the therapeutic use of a proteasome inhibitor, e.g., the novel, orally bioavailable carfilzomib (CF). This results in the disruption of the cytosolic complex of the histone deacetylase 6 (HDAC6), the ATPase and segregase p97 and the heat shock factor 1 (HSF1)-a transcription factor involved in the transactivation of heat shock proteins (hsps). In the present studies, we demonstrate that treatment of the pancreatic cancer Hs766T and Panc1 cells with CF increased the levels of misfolded polyubiquitylated proteins, which disrupts the repressive HSF1/hsp90/HDAC6/Vp97 complex. This induces the phosphorylation, nuclear localization and activation of HSF1, which transactivated hsps (e.g., hsp70, hsp40 and hsp27) as an adaptive response to CF-induced proteotoxic stress. Treatment with CF also induced endoplasmic reticulum (ER) stress, represented by upregulation of GRP78 and the pro-apoptotic transcription factor CHOP, which induced the BH3 only pro-apoptotic protein Bim. Treatment with CF also dose-dependently decreased the viability of Hs766T and Panc1 cells. To further elucidate the role of HSF1 in the adaptive, protective response to CF-induced proteotoxic stress, we stably knocked down HSF1 in Hs766T cells. As compared to the control cells, following heat shock, Hs766T cells with knockdown (KD) of HSF1 displayed reduced expression of hsps. In the HSF1-KD versus the control Hs766T cells, treatment with CF resulted in a dose-dependent induction of polyubiquitylated proteins, GRP78, CHOP, and Bim, as well as induced significantly more apoptosis. HSF1-KD versus the control Hs766T cells exhibited markedly lower levels of HDAC6 and, consequently, displayed reduced CF-induced perinuclear protective aggresome formation, as determined by confocal microscopy. Additionally, as compared to the control cells, Hs766T cells with HSF1-KD demonstrated higher levels of p-AMPK and CF (5 to 20 nM) or the pan-HDAC inhibitor panobinostat (PS, 50 nM)-induced autophagy, as demonstrated by the accumulation of LC3-II (by immunoblot analysis) and LC3 puncta by immunofluorescent staining. Importantly, co-treatment with the autophagy inhibitor hydroxy-chloroquine (HCQ) induced more CF-induced cell death of HSF1-KD versus the control Hs766T cells. Using an acid-sensitive mCherry-GFP-LC3 reporter, we determined that the induction of LC3-II in the Hs766T HSF1-KD cells is the result of enhanced autophagic flux and not due to inefficient fusion of autophagosomes with lysosomes. Collectively, these findings indicate that inhibition of the transcriptional activity of HSF1 sensitizes pancreatic cancer cells to CF or PS-induced cells death, which is augmented by co-treatment with an autophagy inhibitor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2076. doi:10.1158/1538-7445.AM2011-2076

Heat shock protein 90 inhibition depletes TrkA levels and signaling in human acute leukemia cells

Nerve growth factor (NGF) induces autophosphorylation and downstream progrowth and prosurvival signaling from the receptor tyrosine kinase TrkA. Overexpression or activating mutation of TrkA has been described in human acute myeloid leukemia cells. In the present study, we show the chaperone association of TrkA with heat shock protein 90 (hsp90) and the inhibitory effect of the hsp90 inhibitor, 17-DMAG, on TrkA levels and signaling in cultured and primary myeloid leukemia cells. Treatment with 17-DMAG disrupted the binding of TrkA with hsp90 and the cochaperone cdc37, resulting in polyubiquitylation, proteasomal degradation, and depletion of TrkA. Exposure to 17-DMAG inhibited NGF-induced p-TrkA, p-AKT, and p-ERK1/2 levels, as well as induced apoptosis of K562, 32D cells with ectopic expression of wild-type TrkA or the constitutively active mutant Delta TrkA, and of primary myeloid leukemia cells. Additionally, 17-DMAG treatment inhibited NGF-induced neurite formation in the rat pheochromocytoma PC-12 cells. Cotreatment with 17-DMAG and K-252a, an inhibitor of TrkA-mediated signaling, induced synergistic loss of viability of cultured and primary myeloid leukemia cells. These findings show that TrkA is an hsp90 client protein, and inhibition of hsp90 depletes TrkA and its progrowth and prosurvival signaling in myeloid leukemia cells. These findings also support further evaluation of the combined activity of an hsp90 inhibitor and TrkA antagonist against myeloid leukemia cells.

Role of CAAT/enhancer binding protein homologous protein in panobinostat-mediated potentiation of bortezomib-induced lethal endoplasmic reticulum stress in mantle cell lymphoma cells

PURPOSE

Bortezomib induces unfolded protein response (UPR) and endoplasmic reticulum stress, as well as exhibits clinical activity in patients with relapsed and refractory mantle cell lymphoma (MCL). Here, we determined the molecular basis of the improved in vitro and in vivo activity of the combination of the pan-histone deacetylase inhibitor panobinostat and bortezomib against human, cultured, and primary MCL cells.

EXPERIMENTAL DESIGN

Immunoblot analyses, reverse transcription-PCR, and immunofluorescent and electron microscopy were used to determine the effects of panobinostat on bortezomib-induced aggresome formation and endoplasmic reticulum stress in MCL cells.

RESULTS

Treatment with panobinostat induced heat shock protein 90 acetylation; depleted the levels of heat shock protein 90 client proteins, cyclin-dependent kinase 4, c-RAF, and AKT; and abrogated bortezomib-induced aggresome formation in MCL cells. Panobinostat also induced lethal UPR, associated with induction of CAAT/enhancer binding protein homologous protein (CHOP). Conversely, knockdown of CHOP attenuated panobinostat-induced cell death of MCL cells. Compared with each agent alone, cotreatment with panobinostat increased bortezomib-induced expression of CHOP and NOXA, as well as increased bortezomib-induced UPR and apoptosis of cultured and primary MCL cells. Cotreatment with panobinostat also increased bortezomib-mediated in vivo tumor growth inhibition and improved survival of mice bearing human Z138C MCL cell xenograft.

CONCLUSION

These findings suggest that increased UPR and induction of CHOP are involved in enhanced anti-MCL activity of the combination of panobinostat and bortezomib.

Abstract C196: Co-treatment with NVP-BEZ235 and heat shock protein (hsp) 90 or pan-deacetylase (DAC) inhibitor is synergistically active against non-small cell lung cancer (NSCLC) cells with mutant RAS and LKB1

Inactivating somatic mutation of LKB1 is found in approximately 30% of NSCLC and is often coincident with activating K-RAS mutation. In a mutant K-RAS-driven model of mouse lung cancer, strong cooperation and aggressive phenotype was seen with hemizygous inactivation of LKB1. Loss of LKB1 results in activation of mTOR pathway while somatic activating mutation in K-RAS results in activation of PI3K/AKT and RAS/RAF/ERK. Therefore therapeutic stratagies which target these pathways may have significant affect on the outcome of these cancers. NVP-BEZ235 is a dual PI3K and mTOR inhibitor and panobinostat (PS) (Novartis Pharmaceuticals Inc) is a pan-histone deacetylase (HDAC) inhibitor, which has been shown to induce proteasomal degradation and depletion of the levels of hsp90 client proteins, including AKT and c-RAF. Here, we determined the effects of BEZ235 and/or PS or AUY922 (an hsp90 inhibitor) on NSCLC A549 and H460 cells with LKB1 and K-RAS mutations (A549 and H460). Treatment with BEZ235 (200 to 1000 nM), PS (25 to 50 nM) or AUY922 (25 to 100 nM) dose-dependently increased % of cells in G2/M and decreased % of cells in S phase of cell cycle, as well as induced apoptosis of the NSCLC cells. Co-treatment with AUY922 or PS increased BEZ235 mediated depletion of p-AKT, p-4EBP1 and p-p70S6K levels, as well as synergistically induced apoptosis of A549 and H460 cells (combination indices &lt; 1.0). Combined therapy with BEZ235 (25 mg/Kg) and PS (10 mg/Kg) or AUY922 (20 mg/Kg) resulted in significantly more tumor growth delay than treatment with each of the agents alone of A549 cell xenografts in nude mice (p &lt; 05). We also determined the activity of BEZ235 and/or PS in the NSCLC H368 cells with mutant K-RAS and either wild-type (H358 cells) or stable knock down of LKB1 expression (H358/LKB1-KD cells), achieved by shRNA against LKB1, mimicking the presence of mutant LKB1. As compared to each agent alone, co-treatment with BEZ235 and PS exhibited a higher level of antitumor synergy against H358/LKB1-KD versus H358 cells. These pre-clinical in vitro and in vivo studies demonstrate that combined treatment with the dual PI3K/mTOR inhibitor BEZ235 and PS or AUY922 could potentially be a promising targeted therapy for NSCLC that harbors K-ras and LKB1 mutations.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C196.

Cotreatment with panobinostat and JAK2 inhibitor TG101209 attenuates JAK2V617F levels and signaling and exerts synergistic cytotoxic effects against human myeloproliferative neoplastic cells

The mutant JAK2V617F tyrosine kinase (TK) is present in the majority of patients with BCR-ABL-negative myeloproliferative neoplasms (MPNs). JAK2V617F activates downstream signaling through the signal transducers and activators of transcription (STAT), RAS/mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3 (PI3)/AKT pathways, conferring proliferative and survival advantages in the MPN hematopoietic progenitor cells (HPCs). Treatment with the pan-histone deacetylase (HDAC) inhibitor panobinostat (PS) is known to inhibit the chaperone function of heat shock protein 90, as well as induce growth arrest and apoptosis of transformed HPCs. Here, we demonstrate that PS treatment depletes the autophosphorylation, expression, and downstream signaling of JAK2V617F. Treatment with PS also disrupted the chaperone association of JAK2V617F with hsp90, promoting proteasomal degradation of JAK2V617F. PS also induced apoptosis of the cultured JAK2V617F-expressing human erythroleukemia HEL92.1.7 and Ba/F3-JAK2V617F cells. Treatment with the JAK2 TK inhibitor TG101209 attenuated JAK2V617F autophosphorylation and induced apoptosis of HEL92.1.7 and Ba/F3-JAK2V617F cells. Cotreatment with PS and TG101209 further depleted JAK/STAT signaling and synergistically induced apoptosis of HEL92.1.7 and Ba/F3-JAK2V617F cells. Cotreatment with TG101209 and PS exerted greater cytotoxicity against primary CD34(+) MPN cells than normal CD34(+) HPCs. These in vitro findings suggest combination therapy with HDAC and JAK2V617F inhibitors is of potential value for the treatment of JAK2V617F-positive MPN.

Co-treatment with heat shock protein 90 inhibitor 17-dimethylaminoethylamino-17-demethoxygeldanamycin (DMAG) and vorinostat: a highly active combination against human mantle cell lymphoma (MCL) cells

Heat shock protein (hsp) 90 inhibitors promote proteasomal degradation of pro-growth and pro-survival hsp90 client proteins, including CDK4, c-RAF and AKT, and induce apoptosis of human lymphoma cells. The pan-histone deacetylase inhibitor vorinostat has also been shown to induce growth arrest and apoptosis of lymphoma cells. Here, we determined the effects of the more soluble, orally bio-available, geldanamycin analogue 17-NN-dimethyl ethylenediamine geldanamycin (DMAG, Kosan Biosciences Inc.) and/or vorinostat in cultured and primary human MCL cells. While vorinostat induced accumulation in the G(1) phase, treatment with DMAG arrested MCL cells in the G(2)/M phase of the cell cycle. Both agents dose-dependently induced apoptosis of MCL cells. Vorinostat also induced hyperacetylation of hsp90 and disrupted the association of hsp90 with its co-chaperones p23 and cdc37, as well as with its client proteins CDK4 and c-RAF. Treatment of MCL cells with vorinostat or 17-DMAG was associated with the inductionof p21 and p27, as well as with depletion of c-Myc, c-RAF, AKT and CDK4. Compared to treatment with either agent alone, co-treatment with DMAG and vorinostat markedly attenuated the levels of cyclin D1 and CDK4, as well as of c-Myc, c-RAF and AKT. Combined treatment with DMAG and vorinostat synergistically induced apoptosis of the cultured MCL cells, as well as induced more apoptosis of primary MCL cells than either agent alone. Therefore, these findings support the rationale to determine the in vivo efficacy of co-treatment with vorinostat and DMAG against human MCL cells.

Panobinostat treatment depletes EZH2 and DNMT1 levels and enhances decitabine mediated de-repression of JunB and loss of survival of human acute leukemia cells

The PRC2 complex protein EZH2 is a histone methyltransferase that is known to bind and recruit DNMT1 to the DNA to modulate DNA methylation. Here, we determined that the pan-HDAC inhibitor panobinostat (LBH589) treatment depletes DNMT1 and EZH2 protein levels, disrupts the interaction of DNMT1 with EZH2, as well as de-represses JunB in human acute leukemia cells. Similar to treatment with the hsp90 inhibitor 17-DMAG, treatment with panobinostat also inhibited the chaperone association of heat shock protein 90 with DNMT1 and EZH2, which promoted the proteasomal degradation of DNMT1 and EZH2. Unlike treatment with the DNA methyltransferase inhibitor decitabine, which demethylates JunB promoter DNA, panobinostat treatment mediated chromatin alterations in the JunB promoter. Combined treatment with panobinostat and decitabine caused greater attenuation of DNMT1 and EZH2 levels than either agent alone, which was accompanied by more JunB de-repression and loss of clonogenic survival of K562 cells. Co-treatment with panobinostat and decitabine also caused more loss of viability of primary AML but not normal CD34(+) bone marrow progenitor cells. Collectively, these findings indicate that co-treatment with panobinostat and decitabine targets multiple epigenetic mechanisms to de-repress JunB and exerts antileukemia activity against human acute myeloid leukemia cells.

C/EBPbeta-mediated transcriptional regulation of bcl-xl gene expression in human breast epithelial cells in response to cigarette smoke condensate

In previous studies, we have shown that cigarette smoke condensate (CSC), a surrogate for cigarette smoke, is capable of transforming the spontaneously immortalized human breast epithelial cell line, MCF10A. These transformed cells displayed upregulation of the anti-apoptotic gene, bcl-xl. Upregulation of this gene may impede the apoptotic pathway and allow the accumulation of DNA damage that can lead to cell transformation and carcinogenesis. In the present study, we have determined the mechanism of CSC-mediated transcriptional upregulation of bcl-xl gene expression in MCF10A cells. We cloned the human bcl-xl promoter (pBcl-xLP) and identified putative transcription factor binding sites. Sequential deletion constructs that removed the putative cis-elements were constructed and transfected into MCF10A cells to determine the CSC-responsive cis-element(s) on the pBcl-xLP. Gel-shift, supershift, and chromatin immunoprecipitation (ChIP) analysis confirmed that C/EBPβ specifically bound to a C/EBP-binding site on the pBcl-xLP in vitro and in vivo. Additionally, overexpression of C/EBPβ-LAP2 stimulated pBcl-xLP activity and Bcl-xL protein levels, which mimicked the conditions of CSC treatment. Our results indicate that C/EBPβ regulates bcl-xl gene expression in MCF10A cells in response to CSC treatment, therefore making it a potential target for chemotherapeutic intervention of cigarette smoke-induced breast carcinogenesis.

Cotreatment with vorinostat enhances activity of MK-0457 (VX-680) against acute and chronic myelogenous leukemia cells

PURPOSE

We determined the effects of vorinostat (suberoylanalide hydroxamic acid) and/or MK-0457 (VX-680), an Aurora kinase inhibitor on the cultured human (HL-60, OCI-AML3, and K562) and primary acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML), as well as on the murine pro-B BaF3 cells with ectopic expression of the unmutated and mutant forms of Bcr-Abl.

EXPERIMENTAL DESIGN

Following exposure to MK-0457 and/or vorinostat, apoptosis, loss of viability, as well as activity and levels of Aurora kinase and Bcr-Abl proteins were determined.

RESULTS

Treatment with MK-0457 decreased the phosphorylation of Aurora kinase substrates including serine (S)10 on histone H3 and survivin, and led to aberrant mitosis, DNA endoreduplication as well as apoptosis of the cultured human acute leukemia HL-60, OCI-AML3, and K562 cells. Combined treatment with vorinostat and MK-0457 resulted in greater attenuation of Aurora and Bcr-Abl (in K562) kinase activity and levels as well as synergistically induced apoptosis of OCI-AML3, HL-60, and K562 cells. MK-0457 plus vorinostat also induced synergistic apoptosis of BaF3 cells with ectopic overexpression of wild-type or mutant Bcr-Abl. Finally, cotreatment with MK-0457 and vorinostat induced more loss of viability of primary AML and imatinib-refractory CML than treatment with either agent alone, but exhibited minimal toxicity to normal CD34+ progenitor cells.

CONCLUSIONS

Combined in vitro treatment with MK-0457 and vorinostat is highly active against cultured and primary leukemia cells. These findings merit in vivo testing of the combination against human AML and CML cells, especially against imatinib mesylate-resistant Bcr-AblT315I-expressing CML Cells.