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Myelodysplastic syndrome (MDS) is a chronic hematologic disorder that frequently evolves to more aggressive stages and in some cases leads to acute myeloid leukemia (AML). MDS arises from mutations in hematopoietic stem cells (HSCs). Thus, to define optimal therapies, it is essential to understand molecular events driving HSC pathogenesis. In this study, we report that during evolution of MDS, malignant HSCs activate distinct cellular programs that render such cells susceptible to therapeutic intervention. Specifically, metabolic analyses of the MDS stem cell compartment show a profound activation of protein synthesis machinery and increased oxidative phosphorylation. Pharmacological targeting of protein synthesis and oxidative phosphorylation demonstrated potent and selective eradication of MDS stem cells in primary human patient specimens. Taken together, our findings indicate that MDS stem cells are reliant on specific metabolic events and that such properties can be targeted prior to the onset of clinically significant AML, during antecedent MDS. Myelodysplastic syndrome (MDS) arises from mutations in hematopoietic stem cells (HSCs). Here, the authors demonstrate that HSCs in higher-risk MDS express the surface marker CD123 and are characterized by activation of protein synthesis machinery and increased oxidative phosphorylation.

Recent advances in targeting leukemic stem cells (LSCs) using venetoclax with azacitidine (ven + aza) has significantly improved outcomes for de novo acute myeloid leukemia (AML) patients. However, patients who relapse after traditional chemotherapy are often venetoclax-resistant and exhibit poor clinical outcomes. We previously described that fatty acid metabolism drives oxidative phosphorylation (OXPHOS) and acts as a mechanism of LSC survival in relapsed/refractory AML. Here, we report that chemotherapy-relapsed primary AML displays aberrant fatty acid and lipid metabolism, as well as increased fatty acid desaturation through the activity of fatty acid desaturases 1 and 2, and that fatty acid desaturases function as a mechanism of recycling NAD+ to drive relapsed LSC survival. When combined with ven + aza, the genetic and pharmacologic inhibition of fatty acid desaturation results in decreased primary AML viability in relapsed AML. This study includes the largest lipidomic profile of LSC-enriched primary AML patient cells to date and indicates that inhibition of fatty acid desaturation is a promising therapeutic target for relapsed AML.

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Leukemia stem cells (LSCs) drive the initiation and perpetuation of AML, are quantifiably associated with worse clinical outcomes, and often persist after conventional chemotherapy resulting in relapse 1 – 5 . In this report, we show that treatment of older patients with AML with the B cell lymphoma 2 (BCL-2) inhibitor venetoclax in combination with azacitidine results in deep and durable remissions and is superior to conventional treatments. We hypothesized that these promising clinical results were due to targeting LSCs. Analysis of LSCs from patients undergoing treatment with venetoclax + azacitidine showed disruption of the tricarboxylic acid (TCA) cycle manifested by decreased α-ketoglutarate and increased succinate levels, suggesting inhibition of electron transport chain complex II. In vitro modeling confirmed inhibition of complex II via reduced glutathionylation of succinate dehydrogenase. These metabolic perturbations suppress oxidative phosphorylation (OXPHOS), which efficiently and selectively targets LSCs. Our findings show for the first time that a therapeutic intervention can eradicate LSCs in patients with AML by disrupting the metabolic machinery driving energy metabolism, resulting in promising clinical activity in a patient population with historically poor outcomes. Targeting of mitochondrial metabolism in combination with BCL-2 inhibition eradicates leukemia stem cells and induces long-lasting responses in patients with acute myeloid leukemia.

We found that basal‐like breast cancer (BLBC) cells use Cdc42 to inhibit function of the redox/Fyn/c‐Cbl (RFC) pathway, which normally functions to convert small increases in oxidative status into enhanced degradation of c‐Cbl target proteins. Restoration of RFC pathway function by genetic or pharmacological Cdc42 inhibition enabled harnessing of pro‐oxidant effects of low µM tamoxifen (TMX) concentrations – concentrations utilized in trials on multiple tumour types – to suppress division and induce death of BLBC cells in vitro and to confer TMX sensitivity in vivo through oestrogen receptor‐α‐independent mechanisms. Cdc42 knockdown also inhibited generation of mammospheres in vitro and tumours in vivo , demonstrating the additional importance of this pathway in tumour initiating cell (TIC) function. These findings provide a new regulatory pathway that is subverted in cancer cells, a novel means of attacking TIC and non‐TIC aspects of BLBCs, a lead molecule (ML141) that confers sensitivity to low µM TMX in vitro and in vivo and also appear to be novel in enhancing sensitivity to a non‐canonical mode of action of an established therapeutic agent. Graphical Abstract Restoration of the redox/Fyn/c‐Cbl pathway via suppression of Cdc42 function in basal‐like breast cancer (BLBC) cells and tumours confers tamoxifen sensitivity in vitro and in vivo .

Venetoclax with azacitidine (ven/aza) has emerged as a promising regimen for acute myeloid leukemia (AML), with a high percentage of clinical remissions in newly diagnosed patients. However, approximately 30% of newly diagnosed and the majority of relapsed patients do not achieve remission with ven/aza. We previously reported that ven/aza efficacy is based on eradication of AML stem cells through a mechanism involving inhibition of amino acid metabolism, a process which is required in primitive AML cells to drive oxidative phosphorylation. Herein we demonstrate that resistance to ven/aza occurs via up-regulation of fatty acid oxidation (FAO), which occurs due to RAS pathway mutations, or as a compensatory adaptation in relapsed disease. Utilization of FAO obviates the need for amino acid metabolism, thereby rendering ven/aza ineffective. Pharmacological inhibition of FAO restores sensitivity to ven/aza in drug resistant AML cells. We propose inhibition of FAO as a therapeutic strategy to address ven/aza resistance.

In 15 all-new essays, this volume explores how science fiction and fantasy draw on materials from ancient Greece and Rome, ‘displacing’ them from their original settings—in time and space, in points of origins and genre—and encouraging readers to consider similar ‘displacements’ in the modern world. Modern examples from a wide range of media and genres—including Philip Pullman’s His Dark Materials and the novels of Helen Oyeyemi, the Rocky Horror Picture Show and Hayao Miyazaki’s Spirited Away, and the role-playing games Dungeons and Dragons and Warhammer 40K—are brought alongside episodes from ancient myth, important moments from history, and more. All together, these multifaceted studies add to our understanding of how science fiction and fantasy form important areas of classical reception, not only transmitting but also transmuting images of antiquity. The volume concludes with an inspiring personal reflection from the New York Times-bestselling author of speculative fiction, Catherynne M. Valente, offering her perspective on the limitless potential of the classical world to resonate with experience today.

OBJECTIVES/GOALS: Immunomodulatory drugs (IMiDs) are critical to multiple myeloma (MM) disease control. IMiDs act by inducing Cereblon-dependent degradation of IKZF1 and IKZF3, which leads to IRF4 and MYC downregulation (collectively termed the “Ikaros axis”). We therefore hypothesized that IMiD treatment fails to downregulate the Ikaros axis in IMiD resistant MM. METHODS/STUDY POPULATION: To measure IMiD-induced Ikaros axis downregulation, we designed an intracellular flow cytometry assay that measured relative protein levels of IKZF1, IKZF3, IRF4 and MYC in MM cells following ex vivo treatment with the IMiD Pomalidomide (Pom). We established this assay using Pom-sensitive parental and dose-escalated Pom-resistant MM cell lines before assessing Ikaros axis downregulation in CD38+CD138+ MM cells in patient samples (bone marrow aspirates). To assess the Ikaros axis in the context of MM intratumoral heterogeneity, we used a 35-marker mass cytometry panel to simultaneously characterize MM subpopulations in patient samples. Lastly, we determined ex vivo drug sensitivity in patient samples via flow cytometry. RESULTS/ANTICIPATED RESULTS: Our hypothesis was supported in MM cell lines, as resistant lines showed no IMiD-induced decrease in any Ikaros axis proteins. However, when assessed in patient samples, Pom treatment caused a significant decrease in IKZF1, IKZF3 and IRF4 regardless of IMiD sensitivity. Mass cytometry in patient samples revealed that individual Ikaros axis proteins were differentially expressed between subpopulations. When correlating this with ex vivo Pom sensitivity of MM subpopulations, we observed that low IKZF1 and IKZF3 corresponded to Pom resistance. Interestingly, most of these resistant populations still expressed MYC. We therefore assessed whether IMiD resistant MM was MYC dependent by treating with MYCi975. In 88% (7/8) of patient samples tested, IMiD resistant MM cells were sensitive to MYC inhibition. DISCUSSION/SIGNIFICANCE: While our findings did not support our initial hypothesis, our data suggest a mechanism where MYC expression becomes Ikaros axis independent to drive IMiD resistance, and resistant MM is still dependent on MYC. This suggests targeting MYC directly or indirectly via a mechanism to be determined may be an effective strategy to eradicate IMiD resistant MM.

An antibody–drug conjugate (ADC) targeting CD46 conjugated to monomethyl auristatin has a potent anti-myeloma effect in cell lines in vitro and in vivo, and patient samples treated ex vivo. Here, we tested if CD46–ADC may have the potential to target MM-initiating cells (MM-ICs). CD46 expression was measured on primary MM cells with a stem-like phenotype. A patient-derived xenograft (PDX) model was implemented utilizing implanted fetal bone fragments to provide a humanized microenvironment. Engraftment was monitored via serum human light chain ELISA, and at sacrifice via bone marrow and bone fragment flow cytometry. We then tested MM regeneration in PDX by treating mice with CD46–ADC or the nonbinding control–ADC. MM progenitor cells from patients that exhibit high aldehyde dehydrogenase activity also have a high expression of CD46. In PDX, newly diagnosed MM patient samples engrafted significantly more compared to relapsed/refractory samples. In mice transplanted with newly diagnosed samples, CD46–ADC treatment showed significantly decreased engraftment compared to control–ADC treatment. Our data further support the targeting of CD46 in MM. To our knowledge, this is the first study to show preclinical drug efficacy in a PDX model of MM. This is an important area for future study, as patient samples but not cell lines accurately represent intratumoral heterogeneity.

'Frankenstein and Its Classics' is a collection of scholarship dedicated to how Frankenstein and works inspired by it draw on ancient Greek and Roman literature, history, philosophy and myth. Presenting 12 new essays intended for students, scholars and other readers of Mary Shelley's novel, the volume explores classical receptions in some of Frankenstein's most important scenes, sources and adaptations.