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Clonal hematopoiesis (CH) represents clonal expansion of mutated hematopoietic stem cells detectable in the peripheral blood or bone marrow through next generation sequencing. The current prevailing model posits that CH mutations detected in the peripheral blood mirror bone marrow mutations with clones widely disseminated across hematopoietic compartments. We sought to test the hypothesis that all clones are disseminated throughout hematopoietic tissues by comparing CH in hip vs peripheral blood specimens collected at the time of hip replacement surgery. Here, we show that patients with osteoarthritis have a high prevalence of CH, which involve genes encoding epigenetic modifiers and DNA damage repair pathway proteins. Importantly, we illustrate that CH, including clones with variant allele frequencies >10%, can be confined to specific bone marrow spaces and may be eliminated through surgical excision. Future work will define whether clones with somatic mutations in particular genes or clonal fractions of certain sizes are either more likely to be localized or are slower to disseminate into the peripheral blood and other bony sites.

Normal T cells express high levels of B-cell lymphoma-2 (BCL2) protein, and data regarding BCL2 expression status and its diagnostic utility in T-cell lymphoma are scarce. We evaluated BCL2 expression in a series of mature T-cell lymphoproliferations (TCLs) including indolent and more recently recognized entities (follicular helper T-cell [TFH] lymphomas). Sixty-six neoplastic biopsies (60 patients) representing mature nodal, extranodal, and leukemia T-cell neoplasms were collected from three institutes (2 US and 1 Japan) and were compared with reactive T cells in 8 benign tissues/blood and 9 T cell-rich B-cell proliferations. BCL2 immunostaining was performed and scored based on intensity-weighted H-score (0-300). Next-generation sequencing (NGS; 5 cases), BCL2 gene sequencing, and real-time polymerase chain reaction (PCR; 3 cases) were conducted. Association of H-score with overall survival (using proportional hazards modeling) was assessed in nonleukemic TCLs. Most TCLs showed significantly downregulated median BCL2 H-score (125, range: 18-300) with the exception of T-cell prolymphocytic leukemia and hepatosplenic T-cell lymphoma, both of which showed uniform strong retention of BCL2 as did the 8 reactive tissues (median H-score: 280; p = 0.000). Notably all TFH lymphoma CD4 neoplastic T cells, subcutaneous panniculitis-like T-cell lymphoma, CD8 adipocyte-rimming T cells, and T-cell large lymphocyte leukemia with pathogenic STAT5B and TP53 mutation showed BCL2 downregulation. No BCL2 mutations were observed by NGS or sequencing with decreased BCL2 mRNA transcripts by real-time PCR. BCL2 downregulation is pervasive among many TCLs and unrelated to any mutations. There is utility for BCL2 immunostaining in some challenging situations as discussed in this article.

T lymphocyte acute lymphoblastic leukemia (T-ALL) is frequently associated with increased expression of the E protein transcription factor inhibitors TAL1 and LYL1. In mouse models, ectopic expression of Tal1 or Lyl1 in T cell progenitors or inactivation of E2a, is sufficient to predispose mice to develop T-ALL. How E2a suppresses thymocyte transformation is currently unknown. Here, we show that early deletion ofE2a, prior to the DN3 stage, was required for robust leukemogenesis and was associated with alterations in thymus cellularity, T cell differentiation, and gene expression in immature CD4+CD8+ thymocytes. Introduction of wild-type thymocytes into mice with early deletion ofE2aprevented leukemogenesis, or delayed disease onset, and impacted the expression of multiple genes associated with transformation and genome instability. Our data indicate that E2a suppresses leukemogenesis by promoting T cell development and enforcing inter-thymocyte competition, a mechanism that is emerging as a safeguard against thymocyte transformation. These studies have implications for understanding how multiple essential regulators of T cell development suppress T-ALL and support the hypothesis that thymus cellularity is a determinant of leukemogenesis.

There is increasing recognition that pathogenic germ line variants drive the development of hematopoietic cancers in many individuals. Currently, patients with hereditary hematologic malignancies (HHMs) receive similar standard therapies and hematopoietic stem cell transplant (HSCT) approaches as those with sporadic disease. We hypothesize that patients with myeloid malignancies and deleterious germ line predisposition variants have different posttransplant outcomes than those without such alleles. We studied 472 patients with myeloid neoplasms, of whom 26% had deleterious germ line variants and 34% underwent HSCT. Deleterious germ line variants in CHEK2 and DDX41 were most commonly seen in American and Australian cohorts, respectively. Patients with deleterious germ line DDX41 variants had a higher incidence of severe (stage 3-4) acute graft-versus-host disease (GVHD) (38%) than recipients with deleterious CHEK2 variants (0%), other HHM variants (12%), or patients without such germ line variants (9%) (P = .002). Importantly, the use of posttransplant cyclophosphamide reduced the risk of severe acute GVHD in patients receiving HSCT for deleterious germ line DDX41-associated myeloid neoplasms (0% vs 53%, P = .03). Based on these results, we advocate the use of posttransplant cyclophosphamide when individuals with deleterious germ line DDX41 variants undergo allogeneic HSCT for myeloid malignancies, even when transplantation has been performed using wild-type donors.

conference program

The second International Cancer Stem Cell Conference in Cleveland, Ohio, on September 20–23, 2016, convened 330 attendees from academic, industrial, and clinical organizations. It featured a debate on the concepts and challenges of the cancer stem cells (CSC) as well as CSC-centered scientific sessions on clinical trials, genetics and epigenetics, tumor microenvironment, immune suppression, metastasis, therapeutic resistance, and emerging novel concepts. The conference hosted 35 renowned speakers, 100 posters, 20 short talks, and a preconference workshop. The reported advances of CSC research and therapies fostered new collaborations across national and international borders, and inspired the next generation's young scientists. Cancer Res; 77(19); 5222–7. ©2017 AACR.

Background Ovarian cancer is the most fatal gynecologic malignancy in the United States. While chemotherapy is effective in the vast majority of ovarian cancer patients, recurrence and resistance to standard systemic therapy is nearly inevitable. We discovered that activation of the non-receptor tyrosine kinase Lymphocyte Cell-Specific Protein-Tyrosine Kinase (LCK) promoted cisplatin resistance. Here, we hypothesized that treating high grade, platinum resistant endometrioid cancer cells with an LCK inhibitor (LCKi) followed by co-treatment with cisplatin would lead to increased cisplatin efficacy. Our objective was to assess clinical outcomes associated with increased LCK expression, test our hypothesis of utilizing LCKi as pre-treatment followed by co-treatment with cisplatin in platinum resistant ovarian cancer in vitro, and evaluate our findings in vivo to assess LCKi applicability as a therapeutic agent. Results Kaplan-Meier (KM) plotter data indicated LCK expression is associated with significantly worse median progression-free survival (HR 3.19, p = 0.02), and a trend toward decreased overall survival in endometrioid ovarian tumors with elevated LCK expression (HR 2.45, p = 0.41). In vitro, cisplatin resistant ovarian endometrioid cells treated first with LCKi followed by combination LCKi-cisplatin treatment showed decreased cell viability and increased apoptosis. Immunoblot studies revealed LCKi led to increased expression of phosphorylated H2A histone family X ($$\gamma$$ γ -H2AX), a marker for DNA damage. In vivo results demonstrate treatment with LCKi followed by LCKi-cisplatin led to significantly slowed tumor growth. Conclusions We identified a strategy to therapeutically target cisplatin resistant endometrioid ovarian cancer leading to chemosensitization to platinum chemotherapy via treatment with LCKi followed by co-treatment with LCKi-cisplatin.

Internal tandem duplication (-ITD) mutations of Fms-like tyrosine kinase 3 (FLT3) provide growth and pro-survival signals in the context of established driver mutations in FLT3 mutant acute myeloid leukemia (AML). Maternal embryonic leucine zipper kinase (MELK) is an aberrantly expressed gene identified as a target in AML. The MELK inhibitor OTS167 induces cell death in AML including cells with FLT3 mutations, yet the role of MELK and mechanisms of OTS167 function are not understood. OTS167 alone or in combination with tyrosine kinase inhibitors (TKIs) were used to investigate the effect of OTS167 on FLT3 signaling and expression in human FLT3 mutant AML cell lines and primary cells. We describe a mechanism whereby OTS167 blocks FLT3 expression by blocking FLT3 translation and inhibiting phosphorylation of eukaryotic initiation factor 4E–binding protein 1 (4E-BP1) and eukaryotic translation initiation factor 4B (eIF4B). OTS167 in combination with TKIs results in synergistic induction of FLT3 mutant cell death in FLT3 mutant cell lines and prolonged survival in a FLT3 mutant AML xenograft mouse model. Our findings suggest signaling through MELK is necessary for the translation and expression of FLT3-ITD, and blocking MELK with OTS167 represents a viable therapeutic strategy for patients with FLT3 mutant AML.

Lower-risk myelodysplastic syndromes (MDS) are characterized by the presence of dysplasia, low bone marrow blast percentage, low number and depth of cytopenia(s), and relatively good-risk karyotpic and molecular abnormalities. A score of ≤3.5 on the Revised International Prognostic Scoring System classifies patients as lower-risk MDS. Information from a mutational profile of the MDS at time of diagnosis (and over serial time points) can be reassuring for predicted behavior of lower-risk MDS compared with one expected to progress more rapidly (higher-risk MDS). Supportive care continues to be the crux of treatment, although the options to reduce transfusion needs have improved in 2020. Erythropoiesis stimulating agents, lenalidomide, and luspatercept address the most frequent (and symptomatic) cytopenia (anemia) and are started only when patients are transfusion dependent. Patients can derive long-term benefits (years) from these approaches but will often progress to higher-risk MDS. Interestingly, some patients with lower-risk MDS can present with an isolated thrombocytopenia for which thrombopoietin receptor analogs such as romiplostim and eltrombopag are options (as long as blast counts are low). The presence of pancytopenia and or intensifying and unremitting clinical symptoms are often treated with hypomethylating agents or (anti–thymocyte globulin if hypocellular MDS is of concern). Targeted therapies are emerging for small subsets of MDS patients with specific somatic mutations (ie, TP53, IDH1/2, FLT3), although currently, there are no approved, mutation-directed medications to treat MDS.

Simple Summary Myelodysplastic syndrome (MDS) is a disease of the bone marrow, characterized by an inability of the bone marrow to produce normal numbers of peripheral blood cells. There are several different types of MDS, and these are driven by distinct biological pathways. The past several years have seen great advances in developing new treatment strategies based on this molecular understanding of the disease drivers. Thus, accurate diagnosis and effective treatment now rely on an accurate assessment of each patient’s particular disease. Most exciting now is the recognition of precursor conditions that may allow strategies to delay or even prevent MDS development altogether. Abstract Myelodysplastic syndrome (MDS) describes a heterogeneous group of bone marrow diseases, now understood to reflect numerous germline and somatic drivers, characterized by recurrent cytogenetic abnormalities and gene mutations. Precursor conditions including clonal hematopoiesis of indeterminate potential and clonal cytopenia of undetermined significance confer risk for MDS as well as other hematopoietic malignancies and cardiovascular complications. The future is likely to bring an understanding of those individuals who are at the highest risk of progression to MDS and preventive strategies to prevent malignant transformation.

Background Ovarian cancer is the leading cause of gynecologic cancer death in the United States despite effective first-line systemic chemotherapy. Cancer stem cells (CSCs) retain the ability to self-renew and proliferate and may be a means of harboring disease that evades standard treatment strategies. We previously performed a high-throughput screen to assess differential protein expression in ovarian CSCs compared to non-CSCs and observed that Thy-1 was more highly expressed in CSCs. Our primary aim was to validate Thy-1 (CD90) as a cancer stem cell (CSC) marker in epithelial ovarian cancer (EOC), correlate with clinical outcomes, and assess as a potential therapeutic target. Results Kaplan Meier (KM) Plotter data were correlated with survival outcomes. Quantitative real-time PCR, flow cytometry, and immunoblots assessed RNA and protein expression. Limiting dilution assays assessed self-renewal capacity and proliferation assays assessed proliferative capacity. RNA in-situ hybridization was performed on patient specimens to assess feasibility. Thy-1 (CD90) is more highly expressed in ovarian CSCs than non-CSCs, in EOC compared to benign ovarian epithelium (P P P = 0 P = 0.036). Endometrioid ovarian cancers with high Thy-1 have poorer PFS, but no difference in OS (upper quartile PFS 34 v. 11 months, P = 0.013; quartile OS not reached, P = 0.69). In vitro, Thy-1 expression is higher in CSCs versus non-CSCs. EOC cells with high Thy-1 expression demonstrate increased proliferation and self-renewal. Thy-1 knockdown in EOC cells decreases proliferative capacity and self-renewal capacity, and knockdown is associated with decreased expression of stem cell transcription factors NANOG and SOX2. RNA in situ hybridization is feasible in ovarian cancer tissue specimens. Conclusions Thy-1 is a marker of ovarian CSCs. Increased expression of Thy-1 in EOC predicts poor prognosis and is associated with increased proliferative and self-renewal capacity. Thy-1 knockdown decreases proliferative and self-renewal capacity, and represents a potential therapeutic target.

Since the US Food and Drug Administration (FDA) approvals of parenteral decitabine and azacitidine, DNA methyltransferase inhibitors, otherwise referred to as DNA hypomethylating agents (HMAs), have been a mainstay in the treatment of higher-risk myelodysplastic syndromes. The development of oral HMAs has been an area of active interest; however, oral bioavailability has been quite poor due to rapid metabolism by cytidine deaminase (CDA). This led to the development of the novel CDA inhibitor cedazuridine, which was combined with an oral formulation of decitabine. Preclinical work demonstrated a pharmacokinetic and pharmacodynamic profile approximate to parenteral decitabine, leading to early-phase clinical trials of oral cedazuridine-decitabine (C-DEC) in myelodysplastic syndromes and chronic myelomonocytic leukemia (CMML). A combination of oral decitabine 35 mg with oral cedazuridine 100 mg was established as the recommended phase 2 dose. Phase 2 data confirmed bioequivalence of C-DEC when compared with parenteral decitabine, and a larger phase 3 trial has demonstrated similar results, leading to the FDA approval of C-DEC for use in intermediate/high-risk myelodysplastic syndrome (MDS) and CMML. This review will focus upon the current role of HMA therapy in MDS/CMML, preclinical and clinical development of C-DEC, and potential roles of oral HMA therapy in myeloid malignancies moving forward.

Hematopoiesis is hierarchical, and it has been postulated that acute myeloid leukemia (AML) is organized similarly with leukemia stem cells (LSCs) residing at the apex. Limited cells acquired by fluorescence activated cell sorting in tandem with targeted amplicon-based sequencing (LC-FACSeq) enables identification of mutations in small subpopulations of cells, such as LSCs. Leveraging this, we studied clonal compositions of immunophenotypically-defined compartments in AML through genomic and functional analyses at diagnosis, remission and relapse in 88 AML patients. Mutations involving DNA methylation pathways, transcription factors and spliceosomal machinery did not differ across compartments, while signaling pathway mutations were less frequent in putative LSCs. We also provide insights into TP53-mutated AML by demonstrating stepwise acquisition of mutations beginning from the preleukemic hematopoietic stem cell stage. In 10 analyzed cases, acquisition of additional mutations and del(17p) led to genetic and functional heterogeneity within the LSC pool with subclones harboring varying degrees of clonogenic potential. Finally, we use LC-FACSeq to track clonal evolution in serial samples, which can also be a powerful tool to direct targeted therapy against measurable residual disease. Therefore, studying clinically significant small subpopulations of cells can improve our understanding of AML biology and offers advantages over bulk sequencing to monitor the evolution of disease.

Background: Ovarian cancer is the most fatal gynecologic malignancy in the United States. While chemotherapy is effective in the vast majority of ovarian cancer patients, recurrence and resistance to standard systemic therapy is nearly inevitable. We discovered that CD55 via activation of the non-receptor tyrosine kinase Lymphocyte Cell-Specific Protein-Tyrosine Kinase (LCK) promoted cisplatin resistance. Here, we hypothesized that treating high grade, platinum resistant endometrioid cancer cells with an LCK inhibitor (LCKi) followed by co-treatment with cisplatin would lead to increased cisplatin efficacy. Our objective was to assess clinical outcomes associated with increased LCK expression, test our hypothesis of utilizing LCKi as pre-treatment followed by co-treatment with cisplatin in platinum resistant ovarian cancer in vitro, and evaluate our findings in vivo to assess LCKi applicability as a therapeutic agent. Results: Kaplan-Meier (KM) plotter data indicated LCK expression is associated with significantly worse median progression-free survival (HR 3.19, p=0.02), and a trend toward decreased overall survival in endometrioid ovarian tumors with elevated LCK expression (HR 2.45, p=0.41). In vitro, cisplatin resistant ovarian endometrioid cells treated first with LCKi followed by combination LCKi-cisplatin treatment showed decreased cell viability and increased apoptosis. Immunoblot studies revealed LCKi led to increased expression of phosphorylated H2A histone family X (-H2AX), a marker for DNA damage. In vivo results demonstrate treatment with LCKi followed by LCKi-cisplatin leads to significantly slowed tumor growth.Conclusions: We identified a strategy to therapeutically target cisplatin resistant endometrioid ovarian cancer leading to chemosensitization to platinum chemotherapy via treatment with LCKi followed by co-treatment with LCKi-cisplatin.

Patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) have poor outcomes and hematopoietic cell transplantation (HCT) is the only curative treatment. New targeted therapies improved survival in select patients with specific mutations, however management of patients without these molecular alterations is an unmet need. We conducted a phase one study of lenalidomide in combination with cytarabine/idarubicin salvage chemotherapy in patients with R/R AML and high‐risk myelodysplastic syndromes. A total of 33 patients were enrolled in the study (30 AML, 3 MDS), and treated at three dose levels with 3 + 3 design. Dose‐limiting toxicity (DLT) was seen in eight patients, including four hematologic DLTs. The most commonly observed non‐hematologic serious adverse events were febrile neutropenia, rash, sepsis and renal injury. Dose level −1, consisting of 25 mg/d lenalidomide D1‐21, 1 g/m2 cytarabine D5‐8, and 8 mg/m2 idarubicin D5‐7 was determined to be the maximum tolerated dose. Note, 15/33 (45%) of patients were able to receive pre‐planned 21 days of lenalidomide. Overall, 18 patients achieved complete remission (CR) (n = 14) or CR with incomplete count recovery (CRi) (n = 4) with total CR/CRi rate of 56%. The 1‐year and 2‐year overall survival (OS) were 24% and 10%, respectively. Among responders, 10/18 underwent allogeneic HCT and had a 1‐year OS of 40%. There was no molecular pattern associated with response. These data demonstrate that the combination had clinical activity in R/R AML. This regimen should be further investigated for patients who relapsed after HCT, and as a bridge therapy to HCT. (ClinicalTrials.gov identifier: NCT01132586).

Tumors adapt their phenotypes during growth and in response to therapies through dynamic changes in cellular processes. Connexin proteins enable such dynamic changes during development, and their dysregulation leads to disease states. The gap junction communication channels formed by connexins have been reported to exhibit tumor-suppressive functions, including in triple-negative breast cancer (TNBC). However, we find that connexin 26 (Cx26) is elevated in self-renewing cancer stem cells (CSCs) and is necessary and sufficient for their maintenance. Cx26 promotes CSC self-renewal by forming a signaling complex with the pluripotency transcription factor NANOG and focal adhesion kinase (FAK), resulting in NANOG stabilization and FAK activation. This FAK/NANOG-containing complex is not formed in mammary epithelial or luminal breast cancer cells. These findings challenge the paradigm that connexins are tumor suppressors in TNBC and reveal a unique function for Cx26 in regulating the core self-renewal signaling that controls CSC maintenance., Connexin proteins are usually considered as tumor suppressors. Here, the authors show that connexin 26 (Cx26) regulates the self-renewal of breast cancer stem cells via a ternary complex with FAK and NANOG.

Acute lymphoblastic leukemia (ALL) represents 20% of adult leukemias. Recent technologic advances have enabled detailed characterization of the genetic basis of leukemogenesis in ALL, including somatic structural DNA rearrangements and sequence mutations that disrupt lymphoid development, signaling, tumor suppression, and epigenetic modification. These studies also showed differences in the molecular profiles of pediatric vs adult ALL. However, adults with ALL, especially older adults (≥40 years), were underrepresented in these large series. Clinical outcomes of older adults with ALL are inferior to younger patients ( Hematopoietic stem cells accumulate DNA mutations with aging, and age-related clonal hematopoiesis (ARCH) has been linked to increased incidence of myeloid malignancies. The prevalence of ARCH increases logarithmically as the population ages, but its role in lymphoid leukemogenesis has not been fully established. We hypothesize that ARCH is a common precursor lesion for the development of ALL in older adults, and patients with ARCH-associated ALL have different clinical outcomes compared to patients whose disease do not harbor these mutations. We retrospectively studied adults with ALL treated at the University of Chicago and Moffitt Cancer Center between July 2014 and April 2021. Genetic profiling of tumor samples was performed by using Miseq Illumina next-generation sequencing (NGS) platform with a comprehensive sequencing panel covering commonly mutated myeloid and lymphoid genes. We classified pathogenicity using American College of Medical Genetics and Genomics guidelines. In total, 345 patients were studied: 286 (83%) had B-ALL, 49 (14%) had T-ALL and 10 (3%) had early T-precursor (ETP)-ALL. Overall, median age at diagnosis was 47 years (range, 18-88 years), and 211 (61%) were ≥40 years at diagnosis; 154 (45%) were women. Cytogenetic groups were as follows: 24% had Ph+ ALL, 13% had Ph-like ALL, and 3% had ALL with KMT2A rearrangement. The most frequent mutation in our adult ALL cohort was the loss of CDKN2A gene (32%), followed by mutations in TP53 (17%), IKZF1 (16%), NOTCH1 (9%), NRAS (9%), and JAK2 (6%) genes. Mutations involving the recurrently mutated genes in ARCH were seen in 110 of 345 patients (32%) with the following order of frequency: TP53 (17%), DNMT3A (5%), TET2 (4%), RUNX1 (3.5%), ASXL1 (3%), IDH1/2 (2%), BCORL1 (2%), EZH2 (1%), CUX1 (1%), and U2AF1 (1%) (Figure 1A). ARCH-associated mutations were more common in older adults (≥40 years) compared to young adults (41% vs 17%, p< 0.0001). Variant allelic frequencies (VAFs) for the ARCH-associated mutations were higher than the mutations involving signaling pathways, which suggests the ancestral nature of the former and secondary nature of the latter (Figure 1B). We further observed clonal dynamics in patients with serial diagnosis, remission and relapse samples available for sequencing. Founder ARCH clones re-emerged at the time of relapse (patient 92 and 100), and were also detectable at the time of complete remission with persistent measurable residual disease (patient 100) (Figure 1C). The overall survival (OS) for patients with ARCH-associated ALL was shorter than patients without ARCH, but the difference did not reach statistical significance (median OS, 39 months vs 84 months, p= 0.16) (Figure 1D). Our results indicate that ARCH is commonly identified as an ancestral event in older adults with ALL, with TP53 mutations being the most prevalent. Unlike patients with AML and TP53 mutations, patients with ALL and ARCH-associated mutations had comparable clinical outcomes to patients without ARCH. This may reflect the frequent use of antibody-based therapies (i.e. blinatumomab and inotuzumab) at diagnosis (on a clinical trial basis) or relapse in the two centers where these patients were treated. Collectively, these data suggest that ARCH may constitute a fertile soil for acute lymphoblastic leukemogenesis and further studies are warranted to interrogate the dynamic interplay between myeloid and lymphoid compartments of these patients. Figure 1 Figure 1. Disclosures Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Shah: BeiGene: Consultancy, Honoraria; Incyte: Research Funding; Acrotech/Spectrum: Honoraria; Novartis: Consultancy, Other: Expenses; Pfizer: Consultancy, Other: Expenses; Amgen: Consultancy; Servier Genetics: Other; Jazz Pharmaceuticals: Research Funding; Precision Biosciences: Consultancy; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Adaptive Biotechnologies: Consultancy; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses.

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis with varying degrees of dysplasia and peripheral cytopenias. MDS are driven by structural chromosomal alterations and somatic mutations in neoplastic myeloid cells, which are supported by a tumorigenic and a proinflammatory marrow microenvironment. Current treatment strategies for lower-risk MDS focus on improving quality of life and cytopenias, while prolonging survival and delaying disease progression is the focus for higher-risk MDS. Several promising drugs are in the horizon, including the hypoxia-inducible factor stabilizer roxadustat, telomerase inhibitor imetelstat, oral hypomethylating agents (CC-486), TP53 modulators (APR-246 and ALRN-6924), and the anti-CD47 antibody magrolimab. Targeted therapies approved for acute myeloid leukemia treatment, such as isocitrate dehdyrogenase inhibitors and venetoclax, are also being studied for use in MDS. In this review, we provide a brief overview of pathogenesis and current treatment strategies in MDS followed by a discussion of newer agents that are under clinical investigation.

CD55 is a membrane complement regulatory protein that attenuates complement-mediated cytotoxicity. Saygin et al. elucidate a new role for CD55 as a signaling hub for cancer stem cell self-renewal and cisplatin resistance pathways in endometrioid tumors and open a new line of research into chemotherapeutic-refractory cancers., Effective targeting of cancer stem cells (CSCs) requires neutralization of self-renewal and chemoresistance, but these phenotypes are often regulated by distinct molecular mechanisms. Here we report the ability to target both of these phenotypes via CD55, an intrinsic cell surface complement inhibitor, which was identified in a comparative analysis between CSCs and non-CSCs in endometrioid cancer models. In this context, CD55 functions in a complement-independent manner and required lipid raft localization for CSC maintenance and cisplatin resistance. CD55 regulated self-renewal and core pluripotency genes via ROR2/JNK signaling and in parallel cisplatin resistance via lymphocyte-specific protein tyrosine kinase (LCK) signaling, which induced DNA repair genes. Targeting LCK signaling via saracatinib, an inhibitor currently undergoing clinical evaluation, sensitized chemoresistant cells to cisplatin. Collectively, our findings identify CD55 as a unique signaling node that drives self-renewal and therapeutic resistance through a bifurcating signaling axis and provides an opportunity to target both signaling pathways in endometrioid tumors.

Detecting, characterizing, and monitoring rare populations of cells can increase testing sensitivity, give insight into disease mechanism, and inform clinical decision making. One area that can benefit from increased resolution is management of cancers in clinical remission but with measurable residual disease (MRD) by multicolor FACS. Detecting and monitoring genomic clonal resistance to treatment in the setting of MRD is technically difficult and resource intensive due to the limited amounts of disease cells. Here, we describe limited-cell FACS sequencing (LC-FACSeq), a reproducible, highly sensitive method of characterizing clonal evolution in rare cells relevant to different types of acute and chronic leukemias. We demonstrate the utility of LC-FACSeq for broad multigene gene panels and its application for monitoring sequential acquisition of mutations conferring therapy resistance and clonal evolution in long-term ibrutinib treatment of patients with chronic lymphocytic leukemia. This technique is generalizable for monitoring of other blood and marrow infiltrating cancers.

Tumors are composed of non-homogeneous cell populations exhibiting varying degrees of genetic and functional heterogeneity. Cancer stem cells (CSCs) are capable of sustaining tumors by manipulating genetic and non-genetic factors to metastasize, resist treatment, and maintain the tumor microenvironment. Understanding the key traits and mechanisms of CSC survival provides opportunities to improve patient outcomes via improved prognostic models and therapeutics. Here, we review the clinical significance of CSCs and results of potential CSC-targeting therapies in various cancers. We discuss barriers to translating cues from pre-clinical models into clinical applications and propose new strategies for rational design of future anti-CSC trials.

// Andrew Wiechert 1, 2, * , Caner Saygin 1, * , Praveena S. Thiagarajan 1 , Vinay S. Rao 1 , James S. Hale 1 , Nikhil Gupta 3 , Masahiro Hitomi 1, 3, 4 , Anil Belur Nagaraj 5 , Analisa DiFeo 5 , Justin D. Lathia 1, 3, 4, 5 , Ofer Reizes 1, 3, 4, 5 1 Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA 2 Division of Gynecological Oncology, Women’s Health Institute, Cleveland Clinic, Cleveland, OH 44195, USA 3 Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195 4 Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA 5 Department of Case Comprehensive Cancer Center, Cleveland, OH 44106, USA * These authors contributed equally to this work Correspondence to: Ofer Reizes, e-mail: reizeso@ccf.org Justin D. Lathia, e-mail: lathiaj@ccf.org Keywords: cancer stem cell, ovarian cancer, cisplatin, NANOG Received: December 01, 2015 Accepted: March 31, 2016 Published: April 20, 2016 ABSTRACT The mainstay of treatment for ovarian cancer is platinum-based cytotoxic chemotherapy. However, therapeutic resistance and recurrence is a common eventuality for nearly all ovarian cancer patients, resulting in poor median survival. Recurrence is postulated to be driven by a population of self-renewing, therapeutically resistant cancer stem cells (CSCs). A current limitation in CSC studies is the inability to interrogate their dynamic changes in real time. Here we utilized a GFP reporter driven by the NANOG-promoter to enrich and track ovarian CSCs. Using this approach, we identified a population of cells with CSC properties including enhanced expression of stem cell transcription factors, self-renewal, and tumor initiation. We also observed elevations in CSC properties in cisplatin-resistant ovarian cancer cells as compared to cisplatin-naive ovarian cancer cells. CD49f, a marker for CSCs in other solid tumors, enriched CSCs in cisplatin-resistant and -naive cells. NANOG-GFP enriched CSCs (GFP+ cells) were more resistant to cisplatin as compared to GFP-negative cells. Moreover, upon cisplatin treatment, the GFP signal intensity and NANOG expression increased in GFP-negative cells, indicating that cisplatin was able to induce the CSC state. Taken together, we describe a reporter-based strategy that allows for determination of the CSC state in real time and can be used to detect the induction of the CSC state upon cisplatin treatment. As cisplatin may provide an inductive stress for the stem cell state, future efforts should focus on combining cytotoxic chemotherapy with a CSC targeted therapy for greater clinical utility.

7515 Background: Therapy-related AML (tAML) is a long-term complication of cytotoxic cancer therapy. It is characterized by adverse genetics and inferior survival outcomes when compared to de novo AML. A proposed mechanism in tAML pathogenesis includes treatment-induced selection of clones harboring pre-existing mutations (i.e. clonal hematopoiesis, CH). We hypothesize that genotoxic therapies used to treat prior malignancy drive leukemogenesis through different mechanisms leading to unique clonal compositions. Methods: AML patients (pts) treated at The Ohio State University between 2015-2018 were included. Genetic profiling was performed using Miseq Illumina platform with a 49-gene targeted sequencing panel at our clinical laboratory. Results: We studied 337 AML pts (Table), of whom 53% had smoking history. Mutations involving ASXL1 were more common in smokers vs non-smokers (14% vs 5.8%, p= .001), while JAK2 mutations were more common in non-smokers (8% vs 1.2%, p= .003). Regarding specific genotoxic therapies and mutations in tAML, we investigated common CH-associated mutations including DNMT3A, TET2, and ASXL1 (DTA mutations). In tAML pts, those exposed to radiotherapy experienced a higher frequency of DTA (52% vs 27%, p= .05), NPM1 (21% vs 0%, p= .002), and SRSF2 (15% vs 0%, p= .01) mutations, and conversely, a lower incidence of TP53 mutations (21% vs 46%, p= .04). Pts with history of cytotoxic chemotherapy had a lower incidence of DTA mutations, including those who received platinum agents (8% vs 49%, p= .005) and taxanes (7% vs 52%, p< .001), but had a higher incidence of TP53 mutations (75% vs 25%, p< .001 for platinum; 53% vs 25%, p= .04 for taxanes). Similarly, alkylators and anthracyclines were associated with lower incidence of DNMT3A (0% vs 20%, p= .009) and ASXL1 (0% vs 12.5%, p= .04) mutations. Conclusions: Different genotoxic agents demonstrate unique effects in leukemia development. Our data suggest that CH clones with DTA mutations may be enriched with smoking and radiotherapy, while cytotoxic chemotherapy may confer a higher incidence of TP53 mutations. Given the adverse prognosis of TP53 mutated AML, identification of pre-existing CH clones might influence treatment selection in solid tumor pts receiving anticancer therapy. [Table: see text]

Background Cyclophosphamide (CYC) remains an important treatment option for Behcet’s syndrome (BS) patients with life-threatening conditions such as arterial aneurysms. However, several adverse events may occur with CYC and this has led to increased use of biologic agents such as rituximab in other vasculitides. Objectives The aim of this study is to delineate the outcome and short and long-term adverse events with CYC use among BS patients. Methods We conducted a retrospective chart review of all BS patients treated with oral or intravenous CYC between 1976 and 2006. Patients were called and a standard form was used for collecting demographic characteristics, CYC indication, cumulative dose of CYC and short-term serious adverse events necessitating the cessation of therapy and/or requiring hospitalisation and long-term adverse events (malignancy and infertility), and outcome. Results We identified 198 (M/W: 184/14) BS patients who had received CYC. After a median follow up of 17 (IQR: 9–26) years after the initiation of CYC therapy, 52 (26%) patients had died within a median duration of 41–12 years, 33 (17%) were lost after a median follow-up of 9 (3.5–14) years, and 113 (57%) were contacted. CYC was prescribed for vascular involvement in 132 (67%) patients, eye involvement in 52 (26%), central nervous system involvement in 5, both vascular and eye involvement in 7 and both vascular and central nervous system involvement in 2 patients. The median duration of CYC use was 12 (IQR:4–24) months and median cumulative dose was 13.5 (IQR:6–49) gr. Among the 52 patients who died, reasons for death were vascular involvement in 26, malignancies in 7, infections in 5 (5 bacterial infections, 1 additional tuberculosis), neurologic involvement in 2, ischaemic stroke in 1, traffic accident in 1, and secondary amyloidosis in 1, esophageal variceal bleeding in 1, and unknown in 5 patients. Sixteen (8%) patients experienced serious adverse events associated with short-term CYC use and 1 of them died due to infection. Among these adverse events, haemorrhagic cystitis occurred in 7 patients, infections in 4 (1/4 died), leukopenia, acute myocardial infarction, anaphylactic reaction, azoospermia, liver toxicity, and severe nausea in 1 patient each. Overall, 16 malignancies were observed in 14 (7%) patients after a median follow up of 25 (IQR:15–26) years. The malignancies were bladder carcinoma (n=4), lung adenocarcinoma (n=3), prostate adenocarcinoma (n=2), carcinoma of unknown primary origin, pancreas adenocarcinoma, t-MDS-AML, lymphoma, colon adenocarcinoma, squamous cell carcinoma and thyroid papillary carcinoma. Among the 113 patients, we were able to question regarding infertility, 67 patients (59%) had children, 22 (19.5%) did not wish to have a child and 24 (21.5%) tried to have a child, but was not able to. Conclusions Short term serious adverse events occurred in 8% of the patients during CYC treatment. During long term follow-up malignancies occurred in 7% and infertility in 21.5% of the patients. These results underline the need for safer and effective alternatives to CYC for serious organ involvement in BS, similar to that in other vasculitides. Disclosure of Interest None declared

Intermediate-risk acute myeloid leukemia (IR-AML) is a clinically heterogeneous disease, for which optimal post-remission therapy is debated. The utility of next-generation sequencing information in decision making for IR-AML has yet to be elucidated. We retrospectively studied 100 IR-AML patients, defined by European Leukemia Net classification, who had mutational information at diagnosis, received intensive chemotherapy and achieved complete remission (CR) at Cleveland Clinic (CC). The Cancer Genome Atlas (TCGA) data were used for validation. In the CC cohort, median age was 58.5 years, 64% had normal cytogenetics, and 31% required >1 induction cycles to achieve CR1. In univariable analysis, patients carrying mutations in DNMT3A, U2AF1, and EZH2 had worse overall and relapse-free survival. After adjusting for other variables, the presence of these mutations maintained an independent effect on survival in both CC and TCGA cohorts. Patients who did not have the mutations and underwent hematopoietic cell transplant (HCT) had the best outcomes. HCT improved outcomes for patients who had these mutations. RUNX1 or ASXL1 mutations did not predict survival, and performance of HCT did not confer a significant survival benefit. Our results provide evidence of clinical utility in considering mutation screening to stratify IR-AML patients after CR1 to guide therapeutic decisions.

Current methods for diagnosis and staging of prostate adenocarcinoma are not sensitive enough to distinguish between patients with indolent disease and those that should receive radical treatment. Epithelial-mesenchymal transition (EMT) is a well-characterized process involved in tumor invasion and metastasis. The aim of this study is to analyze the expression of β-catenin, Snail, and E-cadherin in prostate cancer patients with prospective evaluation of their value in predicting disease-free survival (DFS). One-hundred-and-three consecutive prostate carcinoma patients who underwent radical prostatectomy and 35 patients with benign prostate hyperplasia (BPH) were enrolled. Age, initial PSA level, tumor size and clinical stage were documented for adenocarcinoma patients and they were enrolled in active surveillance with serum PSA levels. Recurrence was defined as PSA level of ≥ 0.2 ng/ml on at least 2 occasions over a 2-month period. Immunohistochemical staining intensity was scored as negative, weakly positive, moderately positive, and strongly positive. For Snail and β-catenin immunoreaction, the tumors were considered nuclear positive when more than 5 % of the nuclei of tumor cells were positively stained. Patients with prostate cancer had weaker β-catenin (p < 0.0001), Snail (p = 0.006), and E-cadherin (p = 0.02) staining when compared to BPH patients and the frequency of nuclear positivity for β-catenin and Snail were higher in adenocarcinoma group (p < 0.0001). Increased expression and nuclear positivity of β-catenin were associated with advanced stage (p = 0.012 and p = 0.003) and higher tumor volume (p = 0.013 and p = 0.002). Additionally, patients with increased Snail expression had higher Gleason scores and tumor volume at presentation (p = 0.008 and p = 0.004). However, there were no significant DFS differences in adenocarcinoma patients who did and did not have β-catenin, Snail, and E-cadherin expression as assessed with log-rank test. Expressions of β-catenin, Snail, and E-cadherin were significantly lower in prostate cancer patients compared to BPH patients and both β-catenin and Snail had nuclear staining pattern in patients with adenocarcinoma. However, none of these markers predicted DFS in 36-month follow up of our cohort.

Behcet's s yndrome (BS) is a multisystem vasculitis with frequent mucocutaneous, joint, eye and visceral organ involvement. From early 2000s, biologic drugs have been increasingly used in the management of BS, enabling rapid and complete remission in most cases with critical organ involvement. Despite the current experience with steroids and traditional immunosuppressives, biologics are exceptionally promising for treatment of resistant cases. Among the biologics used in BS, TNF-alpha antagonists are the oldest and their efficacy has been proven in recalcitrant ocular, vascular, gastrointestinal and neurologic involvements. These drugs have significantly reduced morbidity and mortality in BS and they have an acceptable safety profile. Tocilizumab, an IL6 receptor antibody, has been shown to be effective in BS patients with neurologic involvement and amyloidosis, and IL1β antagonists such as anakinra, canakinumab, gevokizumab were effective in the management of ocular involvement. Studies investigating the efficacy of daclizumab, IL2 receptor antibody, and secukinumab, IL17 monoclonal antibody, in the management of BS with eye involvement failed to demonstrate significant clinical improvement and both studies were halted. A monoclonal vascular endothelial growth factor antagonist, bevacizumab, was shown to be effective in BS-related macular edema. Alemtuzumab and ustekinumab are among other biologics which were effective in controlling disease symptoms. In this review, we discuss the efficacy and safety of various recently developed biologic agents targeting different pathways involved in the pathogenesis of BS.

The evidence that obesity and excess fat in adipose tissue lead to poor prognosis for gynecological cancers is overwhelming. Indeed, obese women are at two to fourfold greater risk of developing endometriod cancer than normal weight women. Further, obese women with a BMI greater than 40 have a sixfold increased relative risk of death from uterine cancer compared to women with BMI of 25 or less. Adipose tissue is now well recognized as an endocrine organ capable of secreting factors called adipokines that act locally and on other organ systems, tissues, and tumors. This chapter will review the existing evidence that adipose-derived factors promote both the initiation and progression of gynecological cancers. Where available, we will discuss the evidence for interaction with specific gynecological organs sites and define future directions for approaches to disrupt the obesity-cancer link.

Outcomes of relapsed adult acute lymphoblastic leukemia (ALL) have improved over time with the introduction of new therapies as well as better supportive care. However, there is still a need for easy-to-use and accurate prognostic tools for patients in first relapse. Whether complete response (CR) with incomplete count recovery (CRh) can be grouped with CR in relapsed ALL trials has not been formally studied. We analyzed 106 ALL patients at first relapse who were treated at three academic centers and achieved CR/CRh. White blood cell count at initial diagnosis and receiving hematopoietic cell transplant (HCT) were independent predictors of overall survival after relapse, while minimal residual disease (MRD) positivity and performance of HCT were predictors of relapse free survival (RFS). Patients who achieved MRD negativity and underwent HCT had the best outcomes. Our results suggest that MRD is a more powerful predictor of outcome than CRh.