VEXAS syndrome: complete molecular remission after hypomethylating therapy

The VEXAS syndrome, a genetically defined autoimmune disease, associated with various hematological neoplasms has been attracting growing attention since its initial description in 2020. While various therapeutic strategies have been explored in case studies, the optimal treatment strategy is still under investigation and allogeneic cell transplantation is considered the only curative treatment. Here, we describe 2 patients who achieved complete molecular remission of the underlying UBA1 mutant clone outside the context of allogeneic HCT. Both patients received treatment with the hypomethylating agent azacitidine, and deep molecular remission triggered treatment de-escalation and even cessation with sustained molecular remission in one of them. Prospective studies are necessary to clarify which VEXAS patients will benefit most from hypomethylating therapy and to understand the variability in the response to different treatment strategies.

Signaling-induced systematic repression of miRNAs uncovers cancer vulnerabilities and targeted therapy sensitivity

Targeted therapies are effective in treating cancer, but success depends on identifying cancer vulnerabilities. In our study, we utilize small RNA sequencing to examine the impact of pathway activation on microRNA (miRNA) expression patterns. Interestingly, we discover that miRNAs capable of inhibiting key members of activated pathways are frequently diminished. Building on this observation, we develop an approach that integrates a low-miRNA-expression signature to identify druggable target genes in cancer. We train and validate our approach in colorectal cancer cells and extend it to diverse cancer models using patient-derived in vitro and in vivo systems. Finally, we demonstrate its additional value to support genomic and transcriptomic-based drug prediction strategies in a pan-cancer patient cohort from the National Center for Tumor Diseases (NCT)/German Cancer Consortium (DKTK) Molecularly Aided Stratification for Tumor Eradication (MASTER) precision oncology trial. In conclusion, our strategy can predict cancer vulnerabilities with high sensitivity and accuracy and might be suitable for future therapy recommendations in a variety of cancer subtypes.

Clinical implications of SRSF2 mutations in AML patients undergoing allogeneic stem cell transplantation

The SRSF2 mutations are frequently found in acute myeloid leukemia (AML) and mostly affect the P95 residue. Mutations in this splicing factor mediate abnormal splicing associated with exon skipping events, including EZH2 as a crucial target. While SRSF2 mutations are enriched in secondary AML and associated with worse outcomes following chemotherapy consolidation, very little is known about the associated biological and clinical implications in AML patients consolidated with allogeneic hematopoietic stemcell transplantation (HSCT). Here we retrospectively analyzed 263 adult AML patients who received an allogeneic HSCT regarding the biological and clinical implications of the SRSF2 mutation status at diagnosis and in morphologic remission at HSCT. We found 12.5% of the patients to be SRSF2 mutated at diagnosis. Mutated patients had increased EZH2 missplicing events with P95H likely driving this pathobiology most effectively. However, the amount of EZH2 missplicing events, as a functional surrogate marker did not associate with relevant biological or clinical characteristics. We observed a persistence of mutations in remission before HSCT in the majority (93%) of SRSF2 mutated AML patients. Importantly, the variant allele frequency (VAF) levels of SRSF2 mutations in remission at HSCT did not correlate with outcomes following HSCT consolidation, limiting the applicability of SRSF2 mutations as a marker for residual AML disease. Following allogeneic HSCT SRSF2 mutated AML patients experienced a 2-year overall survival of 77%, indicating that SRSF2 mutated AML patients may benefit from HSCT consolidation.

Clinical and molecular relevance of genetic variants in the non-coding transcriptome of patients with cytogenetically normal acute myeloid leukemia

Expression levels of long non-coding RNAs (lncRNAs) have been shown to associate with clinical outcome of patients with cytogenetically normal acute myeloid leukemia (CN-AML). However, the frequency and clinical significance of genetic variants in the nucleotide sequences of lncRNAs in AML patients is unknown. Herein, we analyzed total RNA sequencing data of 377 younger adults (aged.

Clinical and molecular relevance of genetic variants in the non-coding transcriptome of patients with cytogenetically normal acute myeloid leukemia

Expression levels of long non-coding RNA (lncRNA) have been shown to associate with clinical outcome of patients with cytogenetically normal acute myeloid leukemia (CN-AML). However, the frequency and clinical significance of genetic variants in the nucleotide sequences of lncRNA in AML patients is unknown. Herein, we analyzed total RNA sequencing data of 377 younger adults (aged <60 years) with CN-AML, who were comprehensively characterized with regard to clinical outcome. We used available genomic databases and stringent filters to annotate genetic variants unequivocally located in the non-coding transcriptome of AML patients. We detected 981 variants, which are recurrently present in lncRNA that are expressed in leukemic blasts. Among these variants, we identified a cytosine-to-thymidine variant in the lncRNA RP5-1074L1.4 and a cytosine-to-thymidine variant in the lncRNA SNHG15, which independently associated with longer survival of CN-AML patients. The presence of the SNHG15 cytosine-to-thymidine variant was also found to associate with better outcome in an independent dataset of CN-AML patients, despite differences in treatment protocols and RNA sequencing techniques. In order to gain biological insights, we cloned and overexpressed both wild-type and variant versions of the SNHG15 lncRNA. In keeping with its negative prognostic impact, overexpression of the wild-type SNHG15 associated with higher proliferation rate of leukemic blasts when compared with the cytosine-to-thymidine variant. We conclude that recurrent genetic variants of lncRNA that are expressed in the leukemic blasts of CN-AML patients have prognostic and potential biological significance.

Precision oncology in AML: validation of the prognostic value of the knowledge bank approach and suggestions for improvement

Recently, a novel knowledge bank (KB) approach to predict outcomes of individual patients with acute myeloid leukemia (AML) was developed using unbiased machine learning. To validate its prognostic value, we analyzed 1612 adults with de novo AML treated on Cancer and Leukemia Group B front-line trials who had pretreatment clinical, cytogenetics, and mutation data on 81 leukemia/cancer-associated genes available. We used receiver operating characteristic (ROC) curves and the area under the curve (AUC) to evaluate the predictive values of the KB algorithm and other risk classifications. The KB algorithm predicted 3-year overall survival (OS) probability in the entire patient cohort (AUC_KB = 0.799), and both younger (< 60 years) (AUC_KB = 0.747) and older patients (AUC_KB = 0.770). The KB algorithm predicted non-remission death (AUC_KB = 0.860) well but was less accurate in predicting relapse death (AUC_KB = 0.695) and death in first complete remission (AUC_KB = 0.603). The KB algorithm’s 3-year OS predictive value was higher than that of the 2017 European LeukemiaNet (ELN) classification (AUC_2017ELN = 0.707, p < 0.001) and 2010 ELN classification (AUC_2010ELN = 0.721, p < 0.001) but did not differ significantly from that of the 17-gene stemness score (AUC_17-gene = 0.732, p = 0.10). Analysis of additional cytogenetic and molecular markers not included in the KB algorithm revealed that taking into account atypical complex karyotype, infrequent recurrent balanced chromosome rearrangements and mutational status of the SAMHD1, AXL and NOTCH1 genes may improve the KB algorithm. We conclude that the KB algorithm has a high predictive value that is higher than those of the 2017 and 2010 ELN classifications. Inclusion of additional genetic features might refine the KB algorithm.

ELN risk stratification and outcomes in secondary and therapy-related AML patients consolidated with allogeneic stem cell transplantation

Secondary or therapy-related acute myeloid leukemia (s/tAML) differs biologically from de novo disease. In general s/tAML patients have inferior outcomes after chemotherapy, compared to de novo cases and often receive allogeneic stem cell transplantation (HSCT) for consolidation. The European LeukemiaNet (ELN) risk stratification system is commonly applied in AML but the clinical significance is unknown in s/tAML. We analyzed 644 s/tAML or de novo AML patients receiving HSCT. s/tAML associated with older age and adverse risk, including higher ELN risk. Overall, s/tAML patients had similar cumulative incidence of relapse (CIR), but higher non-relapse mortality (NRM) and shorter overall survival (OS). In multivariate analyses, after adjustment for ELN risk and pre-HSCT measurable residual disease status, disease origin did not impact outcomes. Within the ELN favorable risk group, CIR was higher in s/tAML compared to de novo AML patients likely due to a different distribution of genetic aberrations, which did not translate into shorter OS. Within the ELN intermediate and adverse group outcomes were similar in de novo and s/tAML patients. Thus, not all s/tAML have a dismal prognosis and outcomes of s/tAML after allogeneic HSCT in remission are comparable to de novo patients when considering ELN risk.

Allogeneic stem cell transplantation mitigates the adverse prognostic impact of high diagnostic BAALC and MN1 expression in AML

For most acute myeloid leukemia (AML) patients, an allogeneic hematopoietic stem cell transplantation (HSCT) offers the highest chance of sustained remissions and long-term survival. At diagnosis, high expression of the AML-associated genes BAALC (brain and acute leukemia, cytoplasmic) and MN1 (meningioma-1) were repeatedly linked to inferior outcomes in patients consolidated with chemotherapy while data for patients receiving HSCT remain limited. Using clinically applicable digital droplet PCR assays, we analyzed the diagnostic BAALC/ABL1 and MN1/ABL1 copy numbers in 302 AML patients. High BAALC/ABL1 and MN1/ABL1 copy numbers associated with common adverse prognostic factors at diagnosis. However, while high diagnostic copy numbers of both genes associated with shorter event free survival (EFS) and overall survival (OS) in patients receiving chemotherapy, there was no prognostic impact in patients undergoing HSCT. Our data suggests that the adverse prognostic impact of high BAALC and MN1 expression are mitigated by allogeneic HSCT. But preHSCT BAALC/ABL1 and MN1/ABL1 assessed in remission prior to HSCT remained prognosticators for EFS and OS independent of the diagnostic expression status. Whether allogeneic HSCT may improve survival for AML patients with high diagnostic BAALC or MN1 expression should be investigated prospectively and may improve informed decisions towards individualized consolidation options in AML.

EGFL7 Antagonizes NOTCH Signaling and Represents a Novel Therapeutic Target in Acute Myeloid Leukemia

PURPOSE

EGF-like domain 7 (EGFL7) is a secreted protein and recently has been shown to play an important role in acute myeloid leukemia (AML); however, the underlying mechanism by which EGFL7 promotes leukemogenesis is largely unknown.

EXPERIMENTAL DESIGN

Using an antibody interaction array, we measured the ability of EGFL7 to bind directly approximately 400 proteins expressed by primary AML blasts. Primary patient samples were stimulated in vitro with recombinant EGFL7 (rEGFL7) or anti-EGFL7 blocking antibody to assess alterations in downstream signaling and the ability to effect blast differentiation and survival. We treated three independent AML models with anti-EGFL7 or IgG1 control to determine whether anti-EGFL7 could prolong survival in vivo.

RESULTS

We found EGFL7 significantly binds several signaling proteins important for normal and malignant hematopoiesis including NOTCH. Stimulation of AML blasts with rEGFL7 reduced NOTCH intracellular domain and NOTCH target gene expression while treatment with an anti-EGFL7 blocking antibody resulted in reactivation of NOTCH signaling, increased differentiation, and apoptosis. Competitive ligand-binding assays showed rEGFL7 inhibits DELTA-like (DLL) 4-mediated NOTCH activation while anti-EGFL7 combined with DLL4 significantly increased NOTCH activation and induced apoptosis. Using three different AML mouse models, we demonstrated that in vivo treatment with anti-EGFL7 alone results in increased survival.

CONCLUSIONS

Our data demonstrate that EGFL7 contributes to NOTCH silencing in AML by antagonizing canonical NOTCH ligand binding. Reactivation of NOTCH signaling in vivo using anti-EGFL7 results in prolonged survival of leukemic mice, supporting the use of EGFL7 as a novel therapeutic target in AML.

Clinical and functional significance of circular RNAs in cytogenetically normal AML

Circular RNAs (circRNAs) are noncoding RNA molecules that display a perturbed arrangement of exons, called backsplicing. To examine the prognostic and biologic significance of circRNA expression in cytogenetically normal acute myeloid leukemia (CN-AML), we conducted whole-transcriptome profiling in 365 younger adults (age 18-60 years) with CN-AML. We applied a novel pipeline, called Massive Scan for circRNA, to identify and quantify circRNA expression. We validated the high sensitivity and specificity of our pipeline by performing RNase R treatment and RNA sequencing in samples of AML patients and cell lines. Unsupervised clustering analyses identified 3 distinct circRNA expression-based clusters with different frequencies of clinical and molecular features. After dividing our cohort into training and validation data sets, we identified 4 circRNAs (circCFLAR, circKLHL8, circSMC1A, and circFCHO2) that were prognostic in both data sets; high expression of each prognostic circRNA was associated with longer disease-free, overall, and event-free survival. In multivariable analyses, high circKLHL8 and high circFCHO2 expression were independently associated with better clinical outcome of CN-AML patients, after adjusting for other covariates. To examine the biologic relevance of circRNA expression, we performed knockdown screening experiments in a subset of prognostic and gene mutation-related candidate circRNAs. We identified circFBXW7, but not its linear messenger RNA, as a regulator of the proliferative capacity of AML blasts. In summary, our findings underscore the molecular associations, prognostic significance, and functional relevance of circRNA expression in CN-AML.

The long non-coding RNA HOXB-AS3 regulates ribosomal RNA transcription in NPM1-mutated acute myeloid leukemia

Long non-coding RNAs (lncRNAs) are important regulatory molecules that are implicated in cellular physiology and pathology. In this work, we dissect the functional role of the HOXB-AS3 lncRNA in patients with NPM1-mutated (NPM1mut) acute myeloid leukemia (AML). We show that HOXB-AS3 regulates the proliferative capacity of NPM1mut AML blasts in vitro and in vivo. HOXB-AS3 is shown to interact with the ErbB3-binding protein 1 (EBP1) and guide EBP1 to the ribosomal DNA locus. Via this mechanism, HOXB-AS3 regulates ribosomal RNA transcription and de novo protein synthesis. We propose that in the context of NPM1 mutations, HOXB-AS3 overexpression acts as a compensatory mechanism, which allows adequate protein production in leukemic blasts.

Mutations associated with a 17-gene leukemia stem cell score and the score's prognostic relevance in the context of the European LeukemiaNet classification of acute myeloid leukemia

Leukemia stem cells (LSC) are more resistant to standard chemotherapy and their persistence during remission can cause relapse, which is still one of the major clinical challenges in the treatment of acute myeloid leukemia (AML). A better understanding of the mutational patterns and the prognostic impact of molecular markers associated with stemness could lead to better clinical management and improve patients’ outcomes. We applied a previously described 17-gene expression score comprising genes differently expressed between LSC and leukemic bulk blasts, for 934 adult patients with de novo AML, and studied associations of the 17-gene LSC score with clinical data and mutation status of 81 genes recurrently mutated in cancer and leukemia. We found that patients with a high 17-gene score were older and had more mutations. The 17-gene score was found to have a prognostic impact in both younger (aged <60 years) and older (aged ≥60 years) patients with AML. We also analyzed the 17-gene LSC score in the context of the 2017 European LeukemiaNet genetic-risk classification and found that for younger patients the score refined the classification, and identified patients currently classified in the European LeukemiaNet Favorable-risk category who had a worse outcome.

Genetic Characterization and Prognostic Relevance of Acquired Uniparental Disomies in Cytogenetically Normal Acute Myeloid Leukemia

PURPOSE

Uniparental disomy (UPD) is a way cancer cells duplicate a mutated gene, causing loss of heterozygosity (LOH). Patients with cytogenetically normal acute myeloid leukemia (CN-AML) do not have microscopically detectable chromosome abnormalities, but can harbor UPDs. We examined the prognostic significance of UPDs and frequency of LOH in patients with CN-AML.Experimental Design: We examined the frequency and prognostic significance of UPDs in a set of 425 adult patients with de novo CN-AML who were previously sequenced for 81 genes typically mutated in cancer. Associations of UPDs with outcome were analyzed in the 315 patients with CN-AML younger than 60 years.

RESULTS

We detected 127 UPDs in 109 patients. Most UPDs were large and typically encompassed all or most of the affected chromosome arm. The most common UPDs occurred on chromosome arms 13q (7.5% of patients), 6p (2.8%), and 11p (2.8%). Many UPDs significantly cooccurred with mutations in genes they encompassed, including 13q UPD with FLT3-internal tandem duplication (FLT3-ITD; P < 0.001), and 11p UPD with WT1 mutations (P = 0.02). Among patients younger than 60 years, UPD of 11p was associated with longer overall survival (OS) and 13q UPD with shorter disease-free survival (DFS) and OS. In multivariable models that accounted for known prognostic markers, including FLT3-ITD and WT1 mutations, UPD of 13q maintained association with shorter DFS, and UPD of 11p maintained association with longer OS.

CONCLUSIONS

LOH mediated by UPD is a recurrent feature of CN-AML. Detection of UPDs of 13q and 11p might be useful for genetic risk stratification of patients with CN-AML.

Expression and functional relevance of long non-coding RNAs in acute myeloid leukemia stem cells

In acute myeloid leukemia (AML), novel therapies are needed to target not only the rapidly dividing AML blasts but also the distinct population of leukemia stem cells (LSCs), which have abnormal self-renewal capacity and increased chemotherapy resistance. Elucidation of the expression and function of deregulated genes in LSCs is critical to specifically target LSCs and may consequently lead to improving outcomes of AML patients. Here, we correlated long non-coding RNA (lncRNA) expression profiles obtained from two RNA-seq datasets of 375 younger (aged <60 years) 76 older (≥60 years) adults with cytogenetically normal AML with a 'core enriched' (CE) gene expression signature (GES) associated with LSCs. We identified a LSC-specific signature of 111 lncRNAs that correlated strongly with the CE-GES. Among the top upregulated LSC-associated lncRNAs, we identified the lncRNA DANCR. Further experiments confirmed that DANCR is upregulated in functionally validated LSC-enriched populations. DANCR knock-down in LSCs resulted in decreased stem-cell renewal and quiescence. Furthermore, we showed that targeting Dancr in vivo using a primary murine model of AML (expressing both Mll partial tandem duplication/Flt3 internal tandem duplication) prolonged the survival of mice after serial transplantation. Our data suggest that LSCs have a distinct lncRNA signature with functional relevance and therapeutic potential.

Complex karyotype in de novo acute myeloid leukemia: typical and atypical subtypes differ molecularly and clinically

Complex karyotype (CK) with ≥3 abnormalities is detected in 10-12% of patients with acute myeloid leukemia (AML) and associated with poor prognosis. The most common unbalanced abnormalities found in CK result in loss of material from the 5q, 7q and/or 17p chromosome arms. The presence of 5q, 7q and/or 17p abnormalities denotes typical CK and their absence denotes atypical CK. Since molecular features of CK-AML are not well-characterized, we investigated mutational status of 81 leukemia/cancer-associated genes in 160 clinically well-characterized patients. They included 136 patients with ≥3 exclusively unbalanced chromosome abnormalities, 96 of whom had a typical CK and 40 atypical CK, and 24 patients with ≥1 balanced abnormality in addition to ≥2 unbalanced ones. Patients with atypical CK-AML differed from those with typical CK-AML: they carried TP53 mutations less often (P<0.001) and more often PHF6 (P=0.008), FLT3-TKD (P=0.02), MED12 (P=0.02) and NPM1 (P=0.02) mutations. They were younger (P=0.007), had higher WBC (P=0.001) and percentages of marrow (P<0.001) and blood (P=0.006) blasts, higher complete remission rates (P=0.02) and longer overall survival (P<0.001), thus indicating that atypical and typical CK-AMLs constitute distinct disease subtypes. We also identified smaller patient subsets within both typical and atypical CK-AML that differed molecularly and clinically.

Abstract 519: The long non-coding RNA (lncRNA) HOXB-AS3 regulates transcription of ribosomal RNA (rRNA) in NPM1-mutated (NPM1mut) acute myeloid leukemia (AML)

Background: A HOXB-locus-embedded lncRNA, named HOXB-AS3 significantly associates with NPM1 mutations in AML. Herein, we evaluate the functional role of HOXB-AS3 expression in NPM1mut AML.

Methods: HOXB-AS3 expression was measured by real-time PCR. Knock-down (KD) of HOXB-AS3 was performed in vitro and in vivo with locked nucleic acid-modified gapmers. RNA antisense purification (RAP), RNA-immunoprecipitation (RIP), and Chromatin-immunoprecipitation (ChIP) experiments were performed according to published protocols.

Results: Among 7 AML cell lines tested, only OCI-AML3 cells, which harbor NPM1mut, showed detectable HOXB-AS3 expression. HOXB-AS3 was more abundant in NPM1mut AML patient (pt) blasts than blasts of AML pts with wild-type NPM1 (P=.001) and bone marrow samples from healthy donors(P=.001). HOXB-AS3 localized in the nucleus and did not associate with isolated polysomes of OCI-AML3 cells.

In vitro HOXB-AS3 KD in OCI-AML3 cells decreased the cells in S phase (P&lt;.001) and increased those in G2/M phase (P=.006). HOXB-AS3 KD reduced the number of formed colonies by OCI-AML3 cells (P=.02). In contrast, overexpression of HOXB-AS3 in K562 cells increased the cells in S phase (P=.02) and decreased those in G0/G1 phase (P=.008). HOXB-AS3 KD in blasts of 3 NPM1mut AML pts decreased the number of formed colonies (P=.03, P=.02, and P&lt;.001). In vivo HOXB-AS3 KD in murine patient-derived xenografts of 2 NPM1mut AML pts prolonged their overall survival (P&lt;.001 and P=.03). RAP-based isolation of HOXB-AS3 and comparative proteomic analyses identified 23 candidate HOXB-AS3-binding proteins. EBP1 was validated as the most avid HOXB-AS3 interactor (P&lt;.001) by RIP experiments. Manipulations of HOXB-AS3 impacted on the (previously reported) EBP1 interaction with NPM1; HOXB-AS3 KD reduced, whereas overexpression of HOXB-AS3 increased the EBP1-NPM1 complex formation. Consequently, HOXB-AS3 KD reduced transcription of rRNA and de novo protein synthesis in OCI-AML3 cells (P&lt;.001 and P=.002) and AML pt blasts (P&lt;.001 and P=.03, respectively). Overexpression of HOXB-AS3 increased rRNA transcription (P&lt;.001), de novo protein synthesis (P=.001). ribosomal DNA (rDNA) promoter occupancy by RNA-Polymerase I (P=.001), and activity of an rDNA promoter-containing luciferase reporter (P=.002) in K562 cells. We hypothesized that HOXB-AS3 guides EBP1 to the rDNA locus. RAP-DNA experiments validated the interaction of HOXB-AS3 with rDNA chromatin (P=.001) and HOXB-AS3 KD decreased the occupancy of the rDNA promoter by EBP1 (P=.002), as shown by ChIP assays.

Conclusions: We describe the function of the HOXB-AS3 lncRNA as a compensatory mechanism, which mediates increased rRNA transcription and adequate protein production, in

NPM1mut AML. From a therapeutic standpoint, we show that HOXB-AS3-targeting yields anti-leukemic activity in pre-clinical models.

Citation Format: Dimitrios Papaioannou, Andreas Petri, Sara Terreri, Charlotte A. Thrue, Deedra Nicolet, Frances A. Collins, Lauren A. Woodward, Prasanthi Kumchala, Malith Karunasiri, Felice Pepe, Marius Bill, Nina Zitzer, Guramrit Singh, Sakari Kaupinnen, Clara D. Bloomfield, Adrienne M. Dorrance, Ramiro Garzon. The long non-coding RNA (lncRNA) HOXB-AS3 regulates transcription of ribosomal RNA (rRNA) in NPM1-mutated (NPM1mut) acute myeloid leukemia (AML) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 519.

Abstract 2455: The long non-coding RNA (lncRNA) DANCR in acute myeloid leukemia (AML) stem cells (LSC)

Introduction: Prognosis for AML patients (pts) is inadequate. Therapeutic strategies are needed to target not only bulk blasts but also the distinct LSCs, which are more resistant to chemotherapy & cause relapse. lncRNAs are non-coding RNA transcripts longer than 200 nucleotides that regulate cellular processes. A functional role in LSCs has yet to be elucidated.

Methods: We derived a LSC-specific lncRNA profile using whole transcriptome sequencing (RNA-seq) data of 377 pts (&lt;60 years) with cytogenetically normal (CN) AML. These data were correlated with a 'core enriched' (CE) gene expression signature representing 44 genes deregulated in LSCs (Eppert, Nat.Med. 2011). DANCR expression in the LSC-enriched compartment was validated using qRT-PCR. Transferrin/antibody conjugated nanoparticle (NP) knock down (KD) was used as an efficient & less toxic avenue to deliver siRNA against DANCR or scramble (SCR) in vitro & in vivo. LSC features (self-renewal, quiescence, engraftment) were analyzed & frequency determined in 3 primary AML samples and a CN-AML (Flt3ITD/WT/MllPTD/WT) mouse model.

Results: 161 lncRNAs were consistently deregulated in CEhigh pts with a p&lt;.001 & a correlation coefficient &gt;.5 (Spearmen correlation test). We chose DANCR to further analyze because it was among the top lncRNAs upregulated in CEhigh pts, is highly conserved between human & mouse, & was previously shown to have a role in promoting stemness in hepatocellular carcinoma (Yuan, Hepatology 2016). We confirmed that DANCR expression was significantly higher in functionally validated LSC enriched populations (p=.05). To assess the role in self-renewal, we KD DANCR in pts cells & found a decrease in colony numbers after replating (average decrease vs SCR: 38.9%, p=.03). Using membrane labeling assays, we found a decrease of quiescent cells after DANCR KD (average decrease: 36.1%, p=.04). Long term colony-initiating cell cultures were performed to determine the LSC frequency & we found significant decreases in the number of LSCs in primary pts samples after DANCR KD (average decrease of LSC frequency: 79.2%, p=.001). Mice transplanted with murine AML cells (CD45.2+) were treated with NP (n=3 per group) for 5 days (d). 2d later, bone marrow was harvested & retransplantated (Tx) using limiting dilutions (2x106, 1x106, 5x105) into irradiated BoyJ (CD45.1+) recipients (n=30). 14d post-Tx, anti-Dancr recipient mice showed a lower engraftment (CD45.2/CD45.1: 37% vs 47%, p=.03) and also a concomitant improvement in survival (p&lt;.001).

Conclusion: We show for the first time that LSCs have a distinct lncRNA profile. Among the highly expressed lncRNAs associated with LSCs we identified & validated DANCR. Our data show that DANCR has an impact on LSC function (self-renewal, quiescence, engraftment) & regulates LSC frequency. DANCR is the first lncRNA shown to have a functional role in LSCs & represents a novel target for AML treatment.

Citation Format: Marius Bill, Malith Karunasiri, Jessica Kohlschmidt, Allison E. Walker, Zachary Brannan, Stefano Volinia, Clara D. Bloomfield, Ramiro Garzon, Adrienne M. Dorrance. The long non-coding RNA (lncRNA) DANCR in acute myeloid leukemia (AML) stem cells (LSC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2455.

High BAALC copy numbers in peripheral blood prior to allogeneic transplantation predict early relapse in acute myeloid leukemia patients

High BAALC expression levels at acute myeloid leukemia diagnosis have been linked to adverse outcomes. Recent data indicate that high BAALC expression levels may also be used as marker for residual disease following acute myeloid leukemia treatment. Allogeneic hematopoietic stem cell transplantation (HSCT) offers a curative treatment for acute myeloid leukemia patients. However, disease recurrence remains a major clinical challenge and identification of high-risk patients prior to HSCT is crucial to improve outcomes. We performed absolute quantification of BAALC copy numbers in peripheral blood prior (median 7 days) to HSCT in complete remission (CR) or CR with incomplete peripheral recovery in 82 acute myeloid leukemia patients using digital droplet PCR (ddPCR) technology. An optimal cut-off of 0.14 BAALC/ABL1 copy numbers was determined and applied to define patients with high or low BAALC/ABL1 copy numbers. High pre-HSCT BAALC/ABL1 copy numbers significantly associated with higher cumulative incidence of relapse and shorter overall survival in univariable and multivariable models. Patients with high pre-HSCT BAALC/ABL1 copy numbers were more likely to experience relapse within 100 days after HSCT. Evaluation of pre-HSCT BAALC/ABL1 copy numbers in peripheral blood by ddPCR represents a feasible and rapid way to identify acute myeloid leukemia patients at high risk of early relapse after HSCT. The prognostic impact was also observed independently of other known clinical, genetic, and molecular prognosticators. In the future, prospective studies should evaluate whether acute myeloid leukemia patients with high pre-HSCT BAALC/ABL1 copy numbers benefit from additional treatment before or early intervention after HSCT.

Lenalidomide in combination with bendamustine and prednisolone in relapsed/refractory multiple myeloma: results of a phase 2 clinical trial (OSHO-#077)

INTRODUCTION

While lenalidomide monotherapy is established for relapsed and/or refractory multiple myeloma (MM) treatment, combination therapies including lenalidomide are still under investigation in a number of phase 2/3 studies. In the current study, a treatment regime of lenalidomide (Revlimid^®), bendamustine and prednisolone (RBP) was tested in patients with relapsed/refractory MM.

METHODS

In the previously completed phase 1 study RBP with a dose of 75 mg/m² bendamustine days 1-2, prednisolone 100 mg days 1-4 and 25 mg lenalidomide days 1-21 was well tolerated.

RESULTS

Between July 2011 and September 2013, 25 patients were included in this analysis. The median number of previous treatments was 1 (range 1-2). Twenty-two patients (88%) responded after at least two cycles of RBP (one sCR, five nCR, eight VGPR and eight PR). The median time to first haematological response was 28 days, and median time to best response was 56 days. Due to increased haematological toxicity a dose reduction in most patients required in subsequent cycles of therapy. The median progression-free and overall survival was 22 and 38 months, respectively. In conclusion RBP is a highly effective therapy for patients with relapsed/refractory MM. In contrast to our phase 1 study, dose reduction was necessary in many patients because of haematological toxicity.

Disruption of the C/EBPα-miR-182 balance impairs granulocytic differentiation

Transcription factor C/EBPα is a master regulator of myelopoiesis and its inactivation is associated with acute myeloid leukemia. Deregulation of C/EBPα by microRNAs during granulopoiesis or acute myeloid leukemia development has not been studied. Here we show that oncogenic miR-182 is a strong regulator of C/EBPα. Moreover, we identify a regulatory loop between C/EBPα and miR-182. While C/EBPα blocks miR-182 expression by direct promoter binding during myeloid differentiation, enforced expression of miR-182 reduces C/EBPα protein level and impairs granulopoiesis in vitro and in vivo. In addition, miR-182 expression is highly elevated particularly in acute myeloid leukemia patients with C-terminal CEBPA mutations, thereby depicting a mechanism by which C/EBPα blocks miR-182 expression. Furthermore, we present miR-182 expression as a prognostic marker in cytogenetically high-risk acute myeloid leukemia patients. Our data demonstrate the importance of a controlled balance between C/EBPα and miR-182 for the maintenance of healthy granulopoiesis.

C/EBPα is a critical transcription factor involved in myelopoiesis and its inactivation is associated with acute myeloid leukemia (AML). Here the authors show a negative feedback loop between C/EBPα and miR-182 and identify this miRNA as a marker of high-risk AML.

Unsupervised hierarchical clustering of surface antigen expression to identify normal karyotype AML patients with distinct disease characteristics and poor outcome

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Background: Surface antigen expression evaluation is part of the standard work-up at acute myeloid leukemia (AML) diagnosis. The biological & prognostic implications of surface antigen expression patterns in normal karyotype (NK) AML patients (pts) remain unknown. Methods: The diagnostic antigen expression patterns of mononuclear cells in bone marrow (BM) of 111 NK-AML pts were assessed using a standard flow cytometric panel. At diagnosis common AML gene mutations (mut) & expression levels were analyzed. Pts received stem cell transplantation (SCT, 98% allogeneic, 2% autologous; median age 63 years [y, range 26-74y]) after induction therapy at our institution. Median follow up was 3.3y. With R’s gplot package unsupervised hierarchical clustering of surface antigens was performed & revealed 4 distinct clusters. Results: Pts in cluster 1 (n = 36) had higher expression of immature, in cluster 2 (n = 31) of thrombocytic/T-cell/erythroid, in cluster 3 (n = 24) of monocytic & in cluster 4 (n = 20) of myeloid surface antigens. All 4 clusters associated with distinct clinical & molecular features. At diagnosis, compared to all others, pts in cluster 1 had a higher CD34+/CD38- cell burden ( P< .001), higher blood blasts ( P< .03) & BM blasts ( P< .06) by trend. They had less NPM1 mut ( P< .001) & DNMT3A mut ( P= .02), were more likely to be EVI1 positive ( P= .03) & had higher EZH2 ( P= .02), RUNX1 ( P= .009), BAALC ( P< .001), ERG ( P= .02) & MN1 ( P< .001) expression. Compared to all others, pts in cluster 1 had a higher cumulative incidence of relapse (CIR, P= .002, at 1y 41% vs 15%) & shorter event-free survival (EFS, P= .02, at 1y 50% vs 69%). In multivariate analysis, cluster 1 pts had a significantly higher CIR (Hazard Ratio [HR] 5.4, P= .01) after adjustment for FLT3-ITD & shorter EFS (HR 2.1, P= .02) after adjustment for FLT3-ITD, age & disease status at SCT. Conclusions: Pts in cluster 1 had high expression of immature surface antigens (eg CD34, CD117, CD13), genes involved in stem cell renewal & worse outcome. Our data indicate a relationship between easily accessible surface antigen expression patterns at diagnosis, molecular disease features & aggressiveness of the NK-AML phenotype.

Prognostic impact of the CD34+/CD38- cell burden in patients with acute myeloid leukemia receiving allogeneic stem cell transplantation

In acute myeloid leukemia (AML), leukemia-initiating cells exist within the CD34+/CD38- cell compartment. They are assumed to be more resistant to chemotherapy, enriched in minimal residual disease cell populations, and responsible for relapse. Here we evaluated clinical and biological associations and the prognostic impact of a high diagnostic CD34+/CD38- cell burden in 169 AML patients receiving an allogeneic stem cell transplantation in complete remission. Here, the therapeutic approach is mainly based on immunological graft-versus-leukemia effects. Percentage of bone marrow CD34+/CD38- cell burden at diagnosis was measured using flow cytometry and was highly variable (median 0.5%, range 0%-89% of all mononuclear cells). A high CD34+/CD38- cell burden at diagnosis associated with worse genetic risk and secondary AML. Patients with a high CD34+/CD38- cell burden had shorter relapse-free and overall survival which may be mediated by residual leukemia-initiating cells in the CD34+/CD38- cell population, escaping the graft-versus-leukemia effect after allogeneic transplantation. Evaluating the CD34+/CD38- cell burden at diagnosis may help to identify patients at high risk of relapse after allogeneic transplantation. Further studies to understand leukemia-initiating cell biology and develop targeting therapies to improve outcomes of AML patients are needed.

A series of case studies on the effect of a midfoot control ankle foot orthosis in the prevention of unresolved pressure areas in children with cerebral palsy

This paper reports on a series of case studies where improvements were sought in muscle tone and gait in children with cerebral palsy. A Midfoot Control Ankle Foot Orthosis (AFO) was developed to control foot position in a cohort of patients with cerebral palsy (CP). The concept of controlling midfoot and hindfoot with an encapsulated internal Supra-Malleolar AFO that fitted into an external AFO was shown to be effective in ambulant children with CP. Some initial problems of compliance were noted and postulated to be due to difficulties associated with previous orthotic devices. Evidence from the case studies suggest that the developed Supra-Malleolar AFO orthoses enables children with CP to maintain mobility without skin tissue damage, delays the need for surgery and at the same time maintains the length of the Triceps Surae (Gastrocnemius and Soleus) complex. Plans for further research are discussed which will contribute to the evidence base for this particular orthotic device.

Carbon isotope fractionation during abiotic reductive dehalogenation of trichloroethene (TCE)

Dehalogenation of trichloroethene (TCE) in the aqueous phase, either on palladium catalysts with hydrogen as the reductant or on metallic iron, was associated with strong changes in delta13C. In general, the delta13C of product phases were more negative than those of the parent compound and were enriched with time and fraction of TCE remaining. For dehalogenation with iron, the delta13C of TCE and products varied from -42/1000 to +5/1000. For the palladium experiments, the final product, ethane, reached the initial delta13C of TCE at completion of the dehalogenation reaction. During dehalogenation, the carbon isotope fractionation between TCE and product phases was not constant. The variation in delta13C of TCE and products offers a new monitoring tool that operates independently of the initial concentration of pollutants for abiotic degradation processes of TCE in the subsurface, and may be useful for evaluation of remediation efficiency.

[The effect of hypolipidemia treatment on the function of kidney transplanted from cadavers]

The high prevalence of hypercholesterolemia (HCh) in kidney transplant recipients probably contributes to the high cardiovascular mortality of these patients. Additionally, HCh is a contributing factor to the progression of renal failure. We conducted a prospective, randomised study with low dose Lovastatin in 42 kidney transplant recipients during 32 weeks, focusing on side effect and kidney function 42 consecutive patients with kidney transplanted in our Institute, with stable renal function (creatinine level < 160 mmol/l) treated with ciclosporine, azathioprine, prednisone were enrolled for the study (regardless of the initial cholesterol level). Every second patient was given Lovastatin 20 mg/night. In the Lovastatin group total cholesterol (TC) and LDL concentration were significantly lower after 6 months of treatment (TC was reduced from 242.5 +/- 12.8 to 220 +/- 15.4 mg/dl, p < 0.05) in Lovastatin group whereas in control group it increased nonsignificantly. Similarly LDL in Lovastatin group decreased from 140.0 +/- 7.0 to 121.3 +/- 10.8 mg/dl, p < 0.02 whereas in control group it increased from 143.6 +/- 5.4 to 169.9 +/- 10.3 mg/dl, p < 0.01. HDL and trigliceride concentrations were unchanged. The Lovastatin treatment did not results in more adverse events than the placebo treatment. Notably, the tendency to increase creatinine level in Lovastatin group was observed from 1.59 +/- 0.17 to 1.74 +/- 0.22 in Lovastatin group versus 1.89 +/- 0.22 to 2.21 +/- 0.35 mg/dl (NS). Low dose Lovastatin treatment seems to be safe and efficient cholesterol-lowering procedure. However we did not observe beneficial effect on kidney graft function.