Durable responses in acute lymphoblastic leukaemia with the use of FLT3 and IDH inhibitors

Data regarding the use of FMS-like tyrosine kinase 3 (FLT3) and isocitrate dehydrogenase 1/2 (IDH1/2) inhibitors in acute lymphoblastic leukaemia (ALL) are lacking. We identified 14 patients with FLT3- or IDH1/2-mutated ALL. Three early T-cell precursor-ALL patients received FLT3 or IDH2 inhibitors. Patient 1 maintains a complete remission (CR) with enasidenib after intolerance to chemotherapy. Patient 2 maintained a CR for 27 months after treatment with enasidenib for relapsed disease. Patient 3 was treated with venetoclax and gilteritinib at the time of relapse and maintained a CR with gilteritinib for 8 months. These cases suggest that FLT3 and IDH inhibitors could represent a viable therapeutic option for ALL patients with these mutations.

Sequential tumor molecular profiling identifies likely germline variants

PURPOSE

To identify likely germline DNA variants from sequential tumor profiling data from hematopoietic malignancies (HMs).

METHODS

The coefficient of variance was calculated from variant allele frequency of next-generation sequencing assays. Variants' likelihood of being germline was ranked on a 1 to 5 scale. Outcomes were examined in patients with such variants.

RESULTS

In a pilot set of 33 genes, 89% of grade 1, 77% of grade 2, 62% of grade 3, 52% of grade 4, and 21% of grade 5 variants were confirmed to be germline. Among those, 22% were pathogenic or likely pathogenic in genes recognized as conferring hereditary HM risk, including BRCA1/2, CHEK2, CSF3R, and DDX41. To determine if this approach identified genes with known autosomal dominant inheritance, we analyzed sequential data from 1336 genes in 1135 HM patients. Among unique variants, 16% occurred in hereditary HM genes, and 15% were deleterious. Patients with grade 1/2 alleles had decreased survival 2 years after initial molecular testing (78% versus 88%, P = .0037) and increased all-cause mortality compared with those without (hazard ratio 2.02, 95% CI 1.18-3.46, P = .019).

CONCLUSION

Variant germline status may be predicted using sequential tumor profiling and patients with likely germline variants experience inferior outcomes compared with those without.

Loss of thymocyte competition underlies the tumor suppressive functions of the E2a transcription factor in T-ALL

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 of E2a, 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 of E2a prevented 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 thymocyte competition suppresses leukemogenesis.

Socioeconomic determinants of the biology and outcomes of acute lymphoblastic leukemia in adults

ABSTRACT

Various socioeconomic and biologic factors affect cancer health disparities and differences in health outcomes. To better characterize the socioeconomic vs biologic determinants of acute lymphoblastic leukemia (ALL) outcomes, we conducted a single-institution, retrospective analysis of adult patients with ALL treated at the University of Chicago (UChicago) from 2010 to 2022 and compared our outcomes with the US national data (the Surveillance, Epidemiology, and End Results [SEER] database). Among 221 adult patients with ALL treated at UChicago, BCR::ABL1 was more frequent in patients with higher body mass index (BMI; odds ratio [OR], 7.64; 95% confidence interval [CI], 1.17-49.9) and non-Hispanic Black (NHB) ancestry (59% vs 24% in non-Hispanic White (NHW) and 20% in Hispanic patients; P = .001). In a multivariable analysis, age (hazard ratio [HR], 6.93; 95% CI, 2.27-21.1) and higher BMI at diagnosis (HR, 10.3; 95% CI, 2.56-41.5) were independent predictors of poor overall survival (OS). In contrast, race or income were not predictors of OS in the UChicago cohort. Analysis of the national SEER database (2010-2020) demonstrated worse survival outcomes in Hispanic and NHB patients than in NHW patients among adolescent and young adults (AYAs) but not in older adults (aged >40 years). Both AYA and older adult patients with higher median household income had better OS than those with lower income. Therefore, multidisciplinary medical care coupled with essential supportive care services offered at centers experienced in ALL care may alleviate the socioeconomic disparities in ALL outcomes in the United States.

Acute lymphoblastic leukemia with myeloid mutations is a high-risk disease associated with clonal hematopoiesis

Myeloid neoplasms arise from pre-existing clonal hematopoiesis (CH), however the role of CH in pathogenesis of ALL is unknown. We found that 18% of adult ALL cases harbored TP53, and 16% had myeloid CH-associated gene mutations. ALL with myeloid mutations (MyM) had distinct genetic and clinical characteristics, associated with inferior survival. By using single cell proteogenomic analysis, we demonstrated that myeloid mutations were present years before the diagnosis of ALL, and a subset of these clones expanded over time to manifest as dominant clones in ALL. Single cell RNA-sequencing revealed upregulation of genes associated with cell survival and resistance to apoptosis in B-ALL with MyM, which responds better to newer immunotherapeutic approaches. These findings define ALL with MyM as a high-risk disease that can arise from antecedent CH and offer new mechanistic insights to develop better therapeutic and preventative strategies.

Dual Targeting of Apoptotic and Signaling Pathways in T-Lineage Acute Lymphoblastic Leukemia

PURPOSE

Relapsed T-acute lymphoblastic leukemia (T-ALL) has limited treatment options. We investigated mechanisms of resistance to BH3 mimetics in T-ALL to develop rational combination strategies. We also looked at the preclinical efficacy of NWP-0476, a novel BCL-2/BCL-xL inhibitor, as single agent and combination therapy in T-ALL.

EXPERIMENTAL DESIGN

We used BH3 profiling as a predictive tool for BH3 mimetic response in T-ALL. Using isogenic control, venetoclax-resistant (ven-R) and NWP-0476-resistant (NWP-R) cells, phosphokinase array was performed to identify differentially regulated signaling pathways.

RESULTS

Typical T-ALL cells had increased dependence on BCL-xL, whereas early T-precursor (ETP)-ALL cells had higher BCL-2 dependence for survival. BCL-2/BCL-xL dual inhibitors were effective against both subtypes of T-lineage ALL. A 71-protein human phosphokinase array showed increased LCK activity in ven-R cells, and increased ACK1 activity in ven-R and NWP-R cells. We hypothesized that pre-TCR and ACK1 signaling pathways are drivers of resistance to BCL-2 and BCL-xL inhibition, respectively. First, we silenced LCK gene in T-ALL cell lines, which resulted in increased sensitivity to BCL-2 inhibition. Mechanistically, LCK activated NF-κB pathway and the expression of BCL-xL. Silencing ACK1 gene resulted in increased sensitivity to both BCL-2 and BCL-xL inhibitors. ACK1 signaling upregulated AKT pathway, which inhibited the pro-apoptotic function of BAD. In a T-ALL patient-derived xenograft model, combination of NWP-0476 and dasatinib demonstrated synergy without major organ toxicity.

CONCLUSIONS

LCK and ACK1 signaling pathways are critical regulators of BH3 mimetic resistance in T-ALL. Combination of BH3 mimetics with tyrosine kinase inhibitors might be effective against relapsed T-ALL.

Paired bone marrow and peripheral blood samples demonstrate lack of widespread dissemination of some CH clones

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.

Loss of thymocyte competition underlies the tumor suppressive functions of the E2a transcription factor in T lymphocyte acute lymphoblastic leukemia

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 of E2a , 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 of E2a prevented 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.

Allogeneic hematopoietic stem cell transplant outcomes in adults with inherited myeloid malignancies

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.

Measurable residual disease in acute lymphoblastic leukemia: methods and clinical context in adult patients

Measurable residual disease (MRD) is the most powerful independent predictor of risk of relapse and long-term survival in adults and children with acute lymphoblastic leukemia (ALL). For almost all patients with ALL there is a reliable method to evaluate MRD, which can be done using multi-color flow cytometry, quantitative polymerase chain reaction to detect specific fusion transcripts or immunoglobulin/T-cell receptor gene rearrangements, and high-throughput next-generation sequencing. While next-generation sequencing-based MRD detection has been increasingly utilized in clinical practice due to its high sensitivity, the clinical significance of very low MRD levels (<10-4) is not fully characterized. Several new immunotherapy approaches including blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor T-cell therapies have demonstrated efficacy in eradicating MRD in patients with B-ALL. However, new approaches to target MRD in patients with T-ALL remain an unmet need. As our MRD detection assays become more sensitive and expanding novel therapeutics enter clinical development, the future of ALL therapy will increasingly utilize MRD as a criterion to either intensify or modify therapy to prevent relapse or de-escalate therapy to reduce treatment-related morbidity and mortality.

B-cell lymphoma-2 (BCL2) downregulation is a useful feature -supporting a neoplastic phenotype in mature T-cell lymphomas

Normal T-cells express high levels of BCL2 protein, data regarding BCL2 expression status and its diagnostic utility in T-cell lymphoma is scarce. We evaluated BCL2 expression in a series of mature T-cell lymphoproliferations 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 (5 cases), BCL2 gene sequencing, and real time-PCR (3 cases) were conducted. Association of H-score with overall survival (using proportional hazards modeling) was assessed in non-leukemic T-cell lymphoproliferations (TCL). Most TCLs showed significantly downregulated median BCL2 H-score (125, range 18-300) with the exception of T-cell prolymphocytic leukemia (T-PLL) and hepatosplenic T-cell lymphoma (HSTL) 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 (SPTCL) CD8 adipocyte-rimming T-cells and T-cell large lymphocyte leukemia (T-LGLL) 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 T-cell lymphoproliferations and unrelated to any mutations. There is utility for BCL2 immunostaining in some challenging situations as discussed in manuscript.

Cytopenias After CD19 Chimeric Antigen Receptor T-Cells (CAR-T) Therapy for Diffuse Large B-Cell Lymphomas or Transformed Follicular Lymphoma: A Single Institution Experience

INTRODUCTION

Patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) have poor outcomes. Treatment with CD19 chimeric antigen receptor (CAR-T) cells, tisagenlecleucel and axicabtagene ciloleucel, has been associated with improved outcomes. Cytopenias were observed in clinical trials with both products; however, little is known regarding the patterns and outcomes of these cytopenias.

SUBJECTS AND METHODS

We reviewed DLBCL patients (n=32) receiving either product between January and September 2018 at our institution.

RESULTS

Median duration of leukopenia, neutropenia, lymphopenia, anemia, and thrombocytopenia was 49, 9, 117.5, 125, and 95.5 days after CAR-T infusion, respectively. Filgrastim was used in 63% of patients, and 50% of patients received red cell or platelet transfusions. With the exception of neutropenia, increase in the duration of cytopenia of any lineage was associated with improvement in progression-free survival, and in overall survival in case of anemia. There was no association between the duration of cytopenias with either cytokine release syndrome or neurotoxicity.

DISCUSSION

Our data suggest a correlation between cytopenias and survival outcomes after CD19 CAR-T therapy. If validated, cytopenia may be proven useful as a biomarker of response and survival after CAR-T therapy.

Cedazuridine/decitabine: from preclinical to clinical development in myeloid malignancies

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.

Therapy for lower-risk MDS

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.

A phase I study of lenalidomide plus chemotherapy with idarubicin and cytarabine in patients with relapsed or refractory acute myeloid leukemia and high-risk myelodysplastic syndrome

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).

LC-FACSeq is a method for detecting rare clones in leukemia

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.

Type of prior genotoxic insult determines the genomic characteristics of therapy-related acute myeloid leukemia

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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]

Thy-1 predicts poor prognosis and is associated with self-renewal in ovarian cancer

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 < 0.001), and is highest in serous EOC (P < 0.05). Serous ovarian cancers with high Thy-1 expression have poorer outcomes (median PFS 15.8 vs. 18.3 months, P = 0 < 0.001; median OS 40.1 v. 45.8 months, 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.

Targeting Cancer Stemness in the Clinic: From Hype to Hope

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.

Cx26 drives self-renewal in triple-negative breast cancer via interaction with NANOG and focal adhesion kinase

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.

Mutations in DNMT3A, U2AF1, and EZH2 identify intermediate-risk acute myeloid leukemia patients with poor outcome after CR1

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.

Reporter Systems to Study Cancer Stem Cells

Cancer stem cells have been identified in primary tumors, patient derived xenografts, and established cancer cell lines. The development of reporters has enabled investigators to rapidly enrich for these cells and more importantly track these cells in real time. Here we describe the current state of the reporter field and their use and limitations in multiple cancers.

Cisplatin induces stemness in ovarian cancer

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-naïve ovarian cancer cells. CD49f, a marker for CSCs in other solid tumors, enriched CSCs in cisplatin-resistant and -naïve 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.

Predicting Successful Phase Advancement and Regulatory Approval in Multiple Myeloma From Phase I Overall Response Rates

PURPOSE

Drug development in oncology is resource intensive, time consuming, and frequently unsuccessful. Here, we hypothesized that therapeutic benefit of published phase I studies of antimyeloma investigational agents was associated with advancement to phase II and future regulatory approval.

PATIENTS AND METHODS

Seventy four phase I trials that treated patients with multiple myeloma (n = 2,408) conducted from 2004 to 2015 were analyzed to assess drug safety, efficacy, phase advancement, and regulatory approval.

RESULTS

The median overall response rate (ORR) for all single-agent trials evaluated was 13.2%. However, the ORR in trials that advanced to phase II was 19%, whereas it was only 4% in trials that failed to advance. The median ORR was 23% for trials testing agents that were ultimately approved by the US Food and Drug Administration compared with only 8% for trials testing agents that were not approved (hazard ratio, 2.21; 95% CI, 2.01 to 2.61; P = .012). Importantly, the absolute number of phase I trials in multiple myeloma, but not the success rate, significantly increased over the period studied. The proportion of industry-sponsored trials also steadily increased over that same period. The ratio of initial dose to maximum tolerated dose was 0.29, suggesting that many patients were undertreated.

CONCLUSION

Investigational agents with higher ORRs in phase I trials were more likely to advance to phase II trials and achieve US Food and Drug Administration approval. Our results suggest that designing phase I trials to maximize the antimyeloma efficacy of a given compound may lead to more successful and cost-effective drug development.

Impact of comorbidities on outcomes of elderly patients with diffuse large B-cell lymphoma

International prognostic index (IPI) has remained the primary prognostic tool in diffuse large B cell lymphoma (DLBCL) for more than 20 years. Even though the disease is more common in older population, the impact of comorbidities, dose reductions, and treatment-related adverse events (TAEs) on the outcome in elderly DLBCL patients has not been well established. We studied 413 consecutive patients aged ≥ 60 years who were treated at the Cleveland Clinic. The median age at diagnosis was 69 years, 58% of patients had high IPI score, and 85% had low Charlson comorbidity index (CCI). Forty percent of patients required dose reductions during treatment, 78% achieved CR, and 70% experienced at least one grade II-IV TAE. High IPI score, high CCI, reduced dose chemotherapy, TAE, and hospitalization were significant predictors of death and relapse. In multivariable analysis, high IPI and CCI were independent predictors of overall and progression free survival. A simple model combining IPI and CCI could reliably distinguish three prognostically separate risk groups. Our results suggest that incorporation of CCI in current prognostic models can improve prognostication of older DLBCL patients and CCI might be a valuable tool in evaluating the eligibility of older patients for clinical trial enrollment.

New Advances and Challenges of Targeting Cancer Stem Cells

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.

CD55 regulates self-renewal and cisplatin resistance in endometrioid tumors

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.

Emerging therapies for acute myeloid leukemia

Acute myeloid leukemia (AML) is characterized by clinical and biological heterogeneity. Despite the advances in our understanding of its pathobiology, the chemotherapy-directed management has remained largely unchanged in the past 40 years. However, various novel agents have demonstrated clinical activity, either as single agents (e.g., isocitrate dehydrogenase (IDH) inhibitors, vadastuximab) or in combination with standard induction/consolidation at diagnosis and with salvage regimens at relapse. The classes of agents described in this review include novel cytotoxic chemotherapies (CPX-351 and vosaroxin), epigenetic modifiers (guadecitabine, IDH inhibitors, histone deacetylase (HDAC) inhibitors, bromodomain and extraterminal (BET) inhibitors), FMS-like tyrosine kinase receptor 3 (FLT3) inhibitors, and antibody-drug conjugates (vadastuximab), as well as cell cycle inhibitors (volasertib), B-cell lymphoma 2 (BCL-2) inhibitors, and aminopeptidase inhibitors. These agents are actively undergoing clinical investigation alone or in combination with available chemotherapy.

Suicidal ideation among patients with Behçet's syndrome

OBJECTIVES

To evaluate the frequency of suicidal ideation among Behçet's syndrome (BS) patients compared to healthy and diseased controls and to delineate possible factors predicting an increase in suicidal ideation.

METHODS

We included consecutive BS patients attending our outpatient clinic, patients with ankylosing spondylitis (AS) and healthy hospital staff as controls. Suicidal ideation was assessed by a standard questionnaire. Linear regression was used to identify the factors associated with suicidal ideation, such as demographic and clinical features, drugs, disease activity assessed using the Behçet's disease current activity form (BDCAF) for BS patients and BASDAI for AS patients, Behçet's disease quality of life (BDQoL) and Beck depression inventory (BDI) score.

RESULTS

We surveyed 303 BS patients, 52 AS patients and 106 healthy controls. Suicidal thoughts, as reflected by a positive response to the first three items of the questionnaire, were higher among BS patients with major organ involvement (42%) than those with mucocutaneous involvement (35%) and the control groups. There were significantly more BS patients with active major organ involvement who had thought to terminate their lives without plans within the last year (25.5%) compared to those with active mucocutaneous involvement (8.7%) and active AS patients (10%) (p=0.012). Patient-reported joint pain (β=-0.155, p=0.046), BDQoL (β=0.176, p=0.032), and BDI (β=0.017, p<0.0001) scores, suicidal thoughts before the onset of BS (β=-0.124, p=0.043), neurologic involvement (β=0.119, p=0.047) and past prednisone use (β=0.212, p=0.005) were independent predictors of suicidal thoughts.

CONCLUSIONS

BS patients with major organ involvement have increased thoughts of suicide during the active stages of their disease. A number of risk factors could help physicians to identify patients with increased suicidal thoughts.

No appreciable decrease in fertility in Behçet's syndrome

OBJECTIVES

Behçet's syndrome (BS) follows an active course during the childbearing years in both men and women. We formally surveyed the infertility rate and the effect of drugs and types of organ involvement on fertility in BS.

METHODS

We compared fertility among BS patients with and without major organ involvement with those with FMF, AS and healthy controls. A structured interview was performed and the medical records of the patients were reviewed to confirm the sites of involvement and drugs they used during their entire follow-up.

RESULTS

The number of female patients who were not able to ever conceive, who were not able to conceive before or after disease onset or who were able to conceive late or only with assisted reproductive technology was not increased among the BS group. The same was true for the male patients to successfully achieve a conception and/or father a child. The average number of children, miscarriages, terminations and ectopic pregnancies were similar among the groups. Infertility was more common in BS patients with major organ involvement who used cyclophosphamide (CYC) compared with those who did not (P = 0.009).

CONCLUSION

Infertility is not appreciably increased among BS patients attending a dedicated outpatient clinic. Major organ involvement does not increase the risk of infertility and CYC is the only drug that seems to compromise fertility in BS.

Dendritic cell sarcoma: a pooled analysis including 462 cases with presentation of our case series

Dendritic cell tumors are extremely rare and current knowledge on these tumors is limited. The characteristics of three dendritic cell sarcoma subtypes and their optimal treatment approaches are not fully clarified. We aimed to make a systematic review of the literature and enrich the current data with five new cases. Pooled analysis of 462 reported cases revealed that the tumor had no age, gender or racial predilection. Our analysis suggests that the young age, advanced stage, intraabdominal involvement and unfavorable histological features (i.e. large tumor size, absence of lymphoplasmacytic infiltration, coagulative necrosis, high mitotic count) may predict poor prognosis. Subtypes of this tumor have different clinical behaviors with interdigitating dendritic cell sarcoma being the most aggressive form. In general, surgery is the most effective treatment modality and adjuvant radiotherapy has no significant effect on overall survival of patients. The role of chemotherapy for the management of advanced disease is controversial.

Expression of MMP-1, MMP-9 and TIMP-2 in prostate carcinoma and their influence on prognosis and survival

PURPOSE

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) participate in tumorigenesis, and their association with disease outcome is highly controversial. The present study investigates the influence of MMP-1, MMP-9 and TIMP-2 on different clinicopathologic variables and disease-free survival (DFS) of patients with prostate carcinoma.

METHODS

Hundred and forty-five cases are included in the study, and levels of MMP/TIMP expressions are assessed in three tissue compartments (i.e., tumor, stroma and normal glands) with immunohistochemistry.

RESULTS

Matrix metalloproteinase-1 expression in tumor cells was associated with lower Gleason scores, pretreatment prostate-specific antigen levels and lower incidence of vascular, perineural and extracapsular invasions. Moreover, MMP-9 positivity and TIMP-2 expression in normal glands were correlated with lower Gleason patterns and early stage at presentation. Expression of MMP in tumor cells and the presence of TIMP-2 in normal glands were associated with better DFS.

CONCLUSION

Variability of MMP/TIMP expressions from case to case makes it difficult to evaluate their impact on clinical outcome. However, these proteins might be new and promising targets for prostate cancer therapy in the future.

Primary central nervous system lymphoma in immunocompetent individuals: a single center experience

Primary central nervous system lymphoma (PCNSL) is defined as the involvement of brain, leptomeninges, eyes or spinal cord by non-Hodgkin lymphoma. The role of various prognostic markers in predicting adverse outcome is debated.

OBJECTIVES

To investigate the clinical and immunohistochemical findings of immunocompetent PCNSL cases (39 cases) diagnosed at the study center, and evaluate the influence of potential prognostic factors on overall survival (OS) of patients.

METHODS

Data regarding patient characteristics, neuroimaging, pathological and immunohistochemical features and follow-up were obtained from patient records. The influence of potential prognostic parameters on OS was investigated by log-rank test and Cox regression analysis.

RESULTS

Patients who received combined chemotherapy and radiotherapy had a significantly better OS when compared to chemotherapy alone. Other variables included in this study were not associated with a significant survival advantage.

CONCLUSION

In this study, we failed to demonstrate a relationship between different clinicopathological variables and OS of patients. Prospective studies with large patient series are needed to investigate other potential prognostic factors.