Prognostic impact of plasma level of NT-pro BNP in patients with microvascular angina – a report from the international cohort study by COVADIS

Aims

Although the importance of microvascular angina (MVA) has been emerging, prognostic biomarkers for MVA remain to be developed. We thus aimed to examine whether plasma level of N-terminal prohormone of brain natriuretic peptide (NT-pro BNP) could predict the prognosis of MVA patients.

Methods

In the international prospective cohort study of MVA patients by the Coronary Vasomotor Disorders International Study (COVADIS) group, we evaluated the association between plasma level of NT-pro BNP and the incidence of major adverse cardiovascular events (MACE), including cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization due to heart failure or unstable angina.

Results

We examined a total of 226 MVA patients (M/F 66/160, 61.9±10.2 [SD] years) with both plasma NT-pro BNP levels and echocardiographic data in the COVADIS study. Plasma NT-pro BNP level was elevated (median 94 pg/ml, IQR 45–190) while mean LVEF (69.2±10.9%) and E/e' (10.7±5.2) were almost normal. During follow-up period of a median of 365 days (IQR 365–482), 29 MACEs occurred. ROC curve analysis identified plasma NT-pro BNP level of 78 pg/ml as the optimal cut-off value. Multivariable logistic regression analysis revealed that plasma NT-pro BNP level ≥78 pg/ml significantly correlated with the incidence of MACE (odds ratio (OR) [95% confidence interval (CI)] 3.11 [1.14–8.49], P=0.03). When divided into 2 groups by NT-pro BNP 78 pg/ml, the Kaplan-Meier survival analysis showed a significantly worse prognosis in the group with NT-pro BNP ≥78 (log lank, P=0.03) (Figure).

Conclusions

These results indicate that plasma NT-pro BNP level is a novel prognostic biomarker for MVA patients.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Japan Heart Foundation

Abstract CT006: Phase Ib expansion trial of the safety and efficacy of the oral ataxia telangiectasia and Rad3-related (ATR) inhibitor elimusertib in advanced solid tumors with DNA damage response (DDR) defects

Introduction: ATR kinase is a critical component of DDR machinery and is activated by DNA damage or replication stress. Elimusertib is a selective ATR inhibitor with promising antitumor activity in pts with advanced solid tumors with ataxia telangiectasia mutated (ATM) protein loss and/or ATM putative deleterious alterations (Yap et al. Cancer Discov 2021). We report here the safety and efficacy of elimusertib in expansion cohorts of pts with a range of cancer types and DDR deficiencies and/or ATM loss. We also explored an alternative dose schedule in pts with ATM aberrations.

Methods: Pts with advanced solid tumors resistant or refractory to standard treatment were screened for pathogenic DDR defects by next-generation sequencing or ATM protein loss by immunohistochemistry (IHC) analysis of baseline tumor tissue. Pts were assigned to cohorts: colorectal cancer (CRC); castration-resistant prostate cancer (CRPC); HER2− breast cancer (BC); gynecologic (GYN, mainly ovarian and endometrial); and advanced cancers with ATM IHC loss. Pts were treated with elimusertib 40 mg twice daily (BID) 3 days on/4 days off (3 on/4 off). A schedule of 3 on/11 off was also explored by dose escalation in pts with ATM loss or inactivating mutation.

Results: 143 pts received ≥1 dose of elimusertib 40 mg BID 3 on/4 off, including 24 CRC, 19 CRPC, 19 BC, 45 GYN, and 36 ATM loss. 56% of pts had ≥4 prior therapy lines. Drug-related grade 3 and 4 treatment-emergent adverse events (TEAEs) were observed in 69% and 15% of pts, respectively, mainly anemia, leukopenia/neutropenia, and thrombocytopenia leading to dose modification but not withdrawal. 32 pts were treated 3 on/11 off with doses from 60 to 120 mg BID. Compared with 3 on/4 off, drug-related grade ≥3 hematologic TEAEs and dose modifications improved at lower doses, with 80 mg 3 on/11 off determined as the recommended dose. In pts receiving elimusertib 3 on/4 off, 5 RECIST partial responses were observed: 1 in ovarian (BRCA1 heterozygous mutation), 1 in BC (BRCA2 mutation), and 3 in ATM IHC loss: 2 CRPC pts both with ATM mutations (1 heterozygous, 1 homozygous), including 1 with FANCA mutation; 1 esophageal with ATM mutation. In pts with ATM IHC loss, objective response rate (ORR) was 9% and disease control rate (DCR) was 65%. A similar ORR was seen on 3 on/11 off in pts with ATM aberrations. In GYN pts, ORR was 2.3% and DCR was 73%.

Conclusions: Elimusertib monotherapy demonstrated clinical activity in pts with DDR defects. Overall safety was manageable and hematologic toxicity improved on the 3 on/11 off schedule. Further biomarker analysis is underway to identify potential gene signatures associated with response. Clinical development of elimusertib in combination with checkpoint inhibitors and chemotherapy is ongoing (NCT04095273, NCT04514497).

Citation Format: Timothy A. Yap, David S. Tan, Anastasios Stathis, Geoffrey I. Shapiro, Satoru Iwasa, Markus Joerger, Jingsong Zhang, Ruth Plummer, Michael Sawyer, Aaron C. Tan, Vincent Castonguay, Nashat Gabrail, Nobuaki Matsubara, Gary Wilkinson, Matthias Ludwig, Yinghui Zhou, Claudia Merz, Joseph Hreiki, Neelesh Sharma, Johan deBono. Phase Ib expansion trial of the safety and efficacy of the oral ataxia telangiectasia and Rad3-related (ATR) inhibitor elimusertib in advanced solid tumors with DNA damage response (DDR) defects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT006.

First-in-human dose escalation study of cyclin-dependent kinase-9 inhibitor VIP152 in patients with advanced malignancies shows early signs of clinical efficacy

PURPOSE

To report on the first-in-human phase I study of VIP152 (NCT02635672), a potent and highly selective CDK9 inhibitor.

PATIENTS AND METHODS

Adults with solid tumors or aggressive non-Hodgkin lymphoma (NHL) who were refractory to or had exhausted all available therapies received VIP152 monotherapy as a 30-minute intravenous, once weekly infusion, as escalating doses (5, 10, 15, 22.5, or 30 mg in 21-day cycles) until the maximum tolerated dose (MTD) was determined.

RESULTS

Thirty-seven patients received {greater than or equal to} 1 VIP152 dose, with 30 mg identified as the MTD based on dose-limiting toxicity of grade 3/4 neutropenia. The most common adverse events were nausea and vomiting (75.7% and 56.8%, respectively), all of grade 1/2 severity. Of the most common events, Grade 3/4 events occurring in > 1 patient were neutropenia (22%), anemia (11%), abdominal pain (8%), increased alkaline phosphatase (8%), and hyponatremia (8%). Day 1 exposure for the MTD exceeded the predicted minimum therapeutic exposure and reproducibly achieved maximal pathway modulation; no accumulation occurred after multiple doses. Seven of 30 patients with solid tumors had stable disease (including 9.5 and 16.8 months in individual patients with pancreatic cancer and salivary gland cancer, respectively), and 2 of 7 patients with high-grade B-cell lymphoma with MYC and BCL2/BCL6 translocations (HGL) achieved durable complete metabolic remission (ongoing at study discontinuation, after 3.7 and 2.3 years of treatment).

CONCLUSION

VIP152 monotherapy, administered intravenously once weekly, demonstrated a favorable safety profile and evidence of clinical benefit in patients with advanced HGL and solid tumors.

Safety and efficacy of VIP152, a CDK9 inhibitor, in patients with double-hit lymphoma (DHL)

7538

Background: PTEFb/CDK9-mediated transcription of short-lived anti-apoptotic survival proteins and oncogenes like MCL-1 and MYC plays a critical role in a variety of cancers. VIP152 (formerly BAY 1251152), a potent and highly selective CDK9 inhibitor, has been evaluated in a Phase 1 dose-escalation study in patients with advanced cancer. The maximum tolerated dose was 30 mg once weekly administered in consecutive 21-day cycles, based on neutropenia as the dose-limiting toxicity (JCO 2018;36:2507; NCT02635672). DHL is defined as dual rearrangement of the MYC gene and either the BCL2 or BCL6 genes; the resulting overexpression of MYC and BCL2/BCL6 make it particularly difficult to treat. Patients with DHL have a poor prognosis and no standard of care. Considering the impact of CDK9 inhibition on MYC, an exploratory cohort of patients with DHL was added to the study. Methods: Patients with refractory or relapsed DHL were eligible. VIP152 was administered once weekly as a 30-minute IV infusion on Days 1, 8 and 15 of a 21-day cycle. Tumor response was assessed according to the revised Cheson criteria (2007). Results: To date a total of 7 patients have been enrolled and were evaluable at the time of data cutoff (24NOV2020). The patients were mostly men (6/7 pts, 86%) with a median (range) age of 70 (58-84) years. All patients received ≥2 prior therapies, including 2 patients with bone marrow transplant. Three of 7 patients (29%) had ≥3 prior therapies. The median time on treatment was 22 days (range 8-1361 days). The most common adverse events of any grade were: constipation, fatigue, nausea (each 3/7 pts, 43%) and abdominal pain, diarrhea, lymphocyte count decrease, neutrophil count decrease, skin infection, tumor pain, and vomiting (each 2/7 pts, 29%). Most were Grade 1 and Grade 2. The Grade 3 adverse events were fatigue, lymphocyte count decrease, neutrophil count decrease (each 1/7 pts, 14%) and tumor pain (2/7 pts, 29%). One Grade 4 lymphocyte count decrease was reported. Two patients had a serious adverse event (Grade 3 syncope and Grade 3 tumor pain). Two patients had dosing held for an adverse event; however, no patient withdrew from treatment due to any adverse events. One death occurred due to disease progression. Pharmacodynamic biomarker analysis showed significant reduction of MYC, PCNA, and MCL-1 mRNA in all patients across multiple timepoints. Antitumor activity consisted of 2 complete metabolic responses in 7 patients (29%) based on investigator-assessed FDG-PET scans. Due to the COVID pandemic, the patients withdrew consent after 3.7 and 2.3 years, respectively, of treatment. Both patients were in complete metabolic response. Conclusions: VIP152 had a manageable safety profile, on-target pharmacodynamic activity and signs of durable monotherapy antitumor activity in patients with DHL. These encouraging results warrant further evaluation of VIP152 in patients with MYC-driven lymphoma and solid tumors. Clinical trial information: NCT02635672.

P14.52 Differential methylation of a single CpG site in the CD95 ligand promoter affects gene activity and correlates with invasiveness of glioma cells

BACKGROUND

CD95 ligand (TNFSF6/APO-1L/FASLG) is a member of the Tumour Necrosis Factor Super Family (TNF-SF). Binding of the CD95 ligand (CD95L) to CD95 expressed on intrinsically apoptosis-resistant cancer cells like glioblastoma, triggers intracellular signal transduction resulting in increased tumour growth and invasiveness. A phase II clinical trial in patients with recurrent glioblastoma (NCT01071837) treated by Asunercept (a recombinant glycosylated fusion protein, which selectively binds and inhibits CD95L activity) was followed by a genome-wide assessment of DNA methylation. Here, a CpG-site (designated CpG2) within the CD95L-promotor was identified, exhibiting differential methylation between Asunercept responders (PFS>5 months) and non-responders (PFS < 2 months) with a significant survival benefit achieved in Asunercept treated patients with low CpG2 methylation (HR 0.34, p = 0.025).

METHODS AND RESULTS

We have performed in vitro studies to establish a link between the CpG2 methylation status and cellular characteristics of glioblastoma cell lines. A 3-dimensional spheroid invasion assay showed that highly methylated glioma cells like T98G did not grow and invade the surrounding matrix as aggressively compared to spheroids formed from low methylated glioma cells, e.g. U87-MG. Invasive growth of U87-MG spheroids in these assays was suppressed in the presence of Asunercept. A 1 kb fragment of the T98G CD95L promoter was subsequently cloned into a CpG-free reporter gene plasmid. Luciferase-based reporter gene assays of in vitro methylated and unmethylated plasmids in transfected HEK cells indicate that the CD95L promoter, despite the observed sparseness of CpG sites, is at least partially regulated by its methylation level. Furthermore, mutational disruption of the CpG2 site completely silenced reporter gene activity in vitro, which insinuates that both methylation level and gene promoter sequence are involved in regulation of the CD95L gene.

CONCLUSION

In essence, the level of CpG2 methylation correlates to aggressiveness of glioma derived cancer spheroids in vitro, and methylation of the CD95L promoter in glioblastoma tissue from patients might warrant use as a potential biomarker predicting response to therapy with Asunercept. We are currently developing a specific and sensitive assay to quantify CpG2 methylation considered as a companion diagnostic for further clinical studies.

Abstract 2: Discovery of BAY 2402234 by phenotypic screening: A human Dihydroorotate Dehydrogenase (DHODH) inhibitor in clinical trials for the treatment of myeloid malignancies

DHODH is a key enzyme in the biosynthesis of pyrimidines and recent studies have renewed interest in this old anti-cancer target. Here, we disclose the discovery of 4-triazolosalicylamides as inhibitors of DHODH and their structure activity relationship (SAR). The hit cluster was discovered during a phenotypic high throughput screen (HTS) of 2.5 million compounds where proliferation of H460 lung cancer cells was used as read-out. DHODH was successfully identified as the molecular target by comparing the activity profile of the hits in a panel of cell lines to a set of inhibitors with known pharmacological activity. The hit compounds showed good cellular potency but had undesirable DMPK properties. Interestingly, the compounds are non-ionizable in contrast to many other DHODH inhibitors and show no potency shift from biochemical to cellular assays. Structural modifications lead to compounds with sub-nanomolar potency in cellular assays and increased metabolic stability enabling the proof of concept in vivo xenograft experiments. Further optimization guided by lipophilicity efficiency and identification of metabolic hot spots resulted in molecules with low clearance and improved solubility. BAY 2402234 was selected as the clinical candidate after side by side comparison of a number of promising compounds. It shows great oral bioavailability, target engagement in all preclinical species tested, induces differentiation in AML models, and has excellent activity in a variety of leukemia models. A clinical phase I study has been initiated in patients with myeloid malignancies. (NCT03404726)

Citation Format: Stefan N. Gradl, Thomas Mueller, Steven Ferrara, Sherif El Sheikh, Andreas Janzer, Han-Jie Zhou, Anders Friberg, Judith Guenther, Martina Schaefer, Timo Stellfeld, Knut Eis, Michael Kroeber, Duy Nguyen, Claudia Merz, Michael Niehues, Detlef Stoeckigt, Sven Christian, Katja Zimmermann, Pascal Lejeune, Michael Bruening, Hanna Meyer, Vera Puetter, David T. Scadden, David B. Sykes, Henrik Seidel, Ashley Eheim, Martin Michels, Andrea Haegebarth, Marcus Bauser. Discovery of BAY 2402234 by phenotypic screening: A human Dihydroorotate Dehydrogenase (DHODH) inhibitor in clinical trials for the treatment of myeloid malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2.

Abstract 3597: BAY 2402234: Preclinical evaluation of a novel, selective dihydroorotate dehydrogenase (DHODH) inhibitor for the treatment of diffuse large B-cell lymphoma (DLBCL)

DLBCL is the most common type of non-Hodgkin lymphoma. It is an aggressive and fast growing tumor with two major molecular subtypes: germinal center (GCB) and activated B-cell like (ABC). While the majority of patients are 60 years or older, DLBCL can occur at any age.

Despite a cure rate of around 50% the need for novel therapies remains high, especially for relapsed/refractory DLBCL patients not eligible for stem cell transplant.

DHODH is a key enzyme in the de novo pyrimidine synthesis converting dihydroorotate to orotate. We recently discovered its role in AML differentiation (Sykes et al 2016, Cell) and we are investigating the novel DHODH inhibitor BAY 2402234 in an ongoing phase I study in myeloid malignancies (NCT03404726). Further screening of non-leukemia cancer types identified DLBCL as highly responsive to DHODH inhibition in preclinical studies.

Here, we disclose for the first time the functional preclinical characterization of BAY 2402234 in DLBCL. BAY 2402234 is a selective low-nanomolar inhibitor of human DHODH enzymatic activity. In vitro it potently inhibits proliferation of DLBCL cell lines in the sub-nanomolar to low-nanomolar range. The anti-proliferative effects can be rescued by uridine supplementation which bypasses DHODH via the salvage pathway and demonstrates the on-target specificity of the inhibitor. In vivo, BAY 2402234 exhibits strong in vivo anti-tumor efficacy in monotherapy in subcutaneous models derived from patient-derived xenograft (PDX) and cell lines representing various DLBCL subtypes, including GCB and ABC. Dose dependent target engagement and drug exposure of BAY 2402234 could be observed by increases in plasma dihydroorotate levels and unbound plasma drug levels after treatment with the inhibitor.

Based on preclinical data presented herein we plan to start clinical investigations of BAY 2402234 in patients with DLBCL in early 2019.

Citation Format: Ashley Eheim, Sven Christian, Hanna Meyer, Detlef Stoeckigt, Claudia Merz, Katja Zimmermann, Marcus Bauser, Andrea Haegebarth, Steven Ferrara, David B. Sykes, David T. Scadden, Stefan Gradl, Andreas Janzer. BAY 2402234: Preclinical evaluation of a novel, selective dihydroorotate dehydrogenase (DHODH) inhibitor for the treatment of diffuse large B-cell lymphoma (DLBCL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3597.

Preclinical Efficacy of the Novel Monocarboxylate Transporter 1 Inhibitor BAY-8002 and Associated Markers of Resistance

The lactate transporter SLC16A1/monocarboxylate transporter 1 (MCT1) plays a central role in tumor cell energy homeostasis. In a cell-based screen, we identified a novel class of MCT1 inhibitors, including BAY-8002, which potently suppress bidirectional lactate transport. We investigated the antiproliferative activity of BAY-8002 in a panel of 246 cancer cell lines and show that hematopoietic tumor cells, in particular diffuse large B-cell lymphoma cell lines, and subsets of solid tumor models are particularly sensitive to MCT1 inhibition. Associated markers of sensitivity were, among others, lack of MCT4 expression, low pleckstrin homology like domain family A member 2, and high pellino E3 ubiquitin protein ligase 1 expression. The antitumor effect of MCT1 inhibition was less pronounced on tumor xenografts, with tumor stasis being the maximal response. BAY-8002 significantly increased intratumor lactate levels and transiently modulated pyruvate levels. In order to address potential acquired resistance mechanisms to MCT1 inhibition, we generated MCT1 inhibitor-resistant cell lines and show that resistance can occur by upregulation of MCT4 even in the presence of sufficient oxygen, as well as by shifting energy generation toward oxidative phosphorylation. These findings provide insight into novel aspects of tumor response to MCT1 modulation and offer further rationale for patient selection in the clinical development of MCT1 inhibitors. Mol Cancer Ther; 17(11); 2285-96. ©2018 AACR.

Abstract DDT02-04: BAY 2402234: A novel, selective dihydroorotate dehydrogenase (DHODH) inhibitor for the treatment of myeloid malignancies

Acute myeloid leukemia (AML), the most common acute leukemia in adults, is an aggressive hematologic malignancy resulting in bone marrow failure with a poor outcome; overall survival is approximately 25% at five years. Treatment options, in particular for the elderly population, are limited. Induction chemotherapy of cytarabine and an anthracycline (7+3) remains unchanged standard of care since its introduction in the early 1970s and there is a high medical need for new therapies (Yates et al. Cancer Chemother Rep 1973). DHODH is a key enzyme in the de novo pyrimidine synthesis converting dihydroorotate to orotate. Using a HOXA9 driven phenotypic screen to overcome differentiation arrest in myeloid cells, we have recently identified DHODH as a surprising novel target to overcome differentiation blockade in AML (Sykes et al. Cell 2016). Differentiation therapy already showed its enormous clinical benefit potential in the small subset of patients diagnosed with acute promyelocytic leukemia (APL) following treatment with all-trans retinoic acid with five-year survival exceeding 85% and should be considered the ultimate therapeutic goal for all AML subsets (Lo-Coco et al. NEJM 2013). Here, we disclose for the first time the structure and functional characterization of the novel DHODH inhibitor BAY 2402234. BAY 2402234 is a selective low-nanomolar inhibitor of human DHODH enzymatic activity. In vitro, it potently inhibits proliferation of AML cell lines in the sub-nanomolar to low-nanomolar range. BAY 2402234 induces differentiation of AML cell lines also in a sub-nanomolar to low-nanomolar range, demonstrating the anticipated mode of action in cellular mechanistic assays. In vivo, BAY 2402234 exhibits strong in vivo anti-tumor efficacy in monotherapy in several subcutaneous and disseminated AML xenografts as well as AML patient-derived xenograft (PDX) models. Target engagement of the novel DHODH inhibitor BAY 2402234 can be observed by increase of tumoral and plasma dihydroorotate levels after treatment with the inhibitor. Consistent with the in vitro data BAY 2402234 induces AML differentiation in vivo as detected by upregulation of differentiation cell surface markers in xenograft and PDX models after treatment with the inhibitor. Furthermore, differentiation-associated transcriptomic changes were evident following a single administration of BAY 2402234 in vivo. The start of clinical investigations of BAY 2402234 is planned for early 2018.

Citation Format: Andreas Janzer, Stefan Gradl, Sven Christian, Katja Zimmermann, Claudia Merz, Hanna Meyer, Timo Stellfeld, Judith Guenther, Detlef Stoeckigt, Henrik Seidel, Pascale Lejeune, Michael Bruening, Ashley Eheim, Thomas Mueller, Ralf Lesche, Martin Michels, Andrea Haegebarth, Marcus Bauser, Sherif El Sheikh, Steven Ferrara, David Sykes, David Scadden. BAY 2402234: A novel, selective dihydroorotate dehydrogenase (DHODH) inhibitor for the treatment of myeloid malignancies [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 DDT02-04.

Abstract 3086: Inhibitors of the enzyme dihydroorotate dehydrogenase, overcome the differentiation blockade in acute myeloid leukemia

The prognosis for adults diagnosed with acute myeloid leukemia (AML) remains poor, with a five-year survival of only 25%. This prognosis is even more dismal in older patients who are not well enough to receive standard induction chemotherapy. Speaking to the need for new therapies is the fact that our therapeutic backbone - a combination of cytarabine and an anthracycline - remains unchanged since 1973. The promise of differentiation therapy was realized in the small subset of patients diagnosed with acute promyelocytic leukemia (APL). Here, treatment in the form of all-trans retinoic acid (ATRA) and arsenic trioxide inverted the survival curve; where APL was once the worst form of myeloid leukemia, it now carries the best prognosis, with a five-year survival exceeding 85%. The goal of this study was thus to develop differentiation therapy for patients with non-promyelocytic AML with the question: “Can we identify small molecules that overcome myeloid differentiation arrest?” A phenotypic differentiation screen in a HOXA9 driven leukemia model followed by target deconvolution, identified DHODH as an unexpected target for overcoming differentiation arrest in AML. We used 2 potent small molecule inhibitors of DHODH to validate this initial finding: Brequinar, a known DHODH inhibitor and an in house compound BAY DHODHi. In several in vitro experiments we demonstrated induction of AML differentiation in a dose dependent fashion. Interestingly, these effects could be completely rescued by addition of uridine, confirming target specificity. Treating mice in multiple genetically diverse AML in vivo models with a DHODH inhibitor led to tumor growth reduction and AML differentiation. Expression analysis of leukemia cells explanted from mice xenografts treated with a DHODH inhibitor demonstrate an early onset of differentiation markers indicating a direct role of DHODH with the onset of differentiation in vivo. The mechanism for selective vulnerability of leukemia cells to DHODH inhibition remains under investigation. Despite the observation that DHODH is expressed in all cells, normal and malignant, mice can tolerate DHODH inhibitor therapy for more than 100 days without weight-loss or other concerning side-effects. Thus, our pre-clinical studies point towards DHODH as a new metabolic target in the differentiation treatment of AML. Hopefully, small molecule DHODH inhibitors will provide a much-needed differentiation therapy for patients with acute myeloid leukemia.

Citation Format: Andreas Janzer, David Sykes, Stefan Gradl, Steven Ferrara, Sven Christian, Claudia Merz, Henrik Seidel, Andreas Bernthaler, Ralf Lesche, Mathias Wawer, David T. Scadden. Inhibitors of the enzyme dihydroorotate dehydrogenase, overcome the differentiation blockade in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3086. doi:10.1158/1538-7445.AM2017-3086

Abstract 1049: Pharmacological characterization of a novel potent nicotinamide phosphoribosyltransferase (NAMPT) inhibitor with robust in vivo efficacy and increased therapeutic index with niacin supplementation

Nicotinamide adenine dinucleotide (NAD+) is an important metabolite and cofactor for a number of cellular processes including genomic stability and epigenetic regulation. Nicotinamide phosphoribosyltransferase (NAMPT) is the rate limiting enzyme in NAD+ salvaging from nicotinamide. Many tumor cells have an increased need for NAD+ and are therefore highly sensitive to NAMPT inhibition. We have developed a selective and potent small molecule inhibitor, Cmpd1, which inhibits the NAMPT enzyme with sub-nanomolar potency. In cells, Cmpd1 treatment leads to an almost complete reduction of both NAD- and ATP-levels, followed by the induction of cell death. In order to identify sensitive cancer subtypes and associated biomarkers, we analyzed cell sensitivity to NAMPT inhibition in a panel of 240 cell lines. Small cell lung cancer and hematological malignancies were particularly sensitive to NAMPT inhibition. Overall, expression levels of NAMPT and NAD+ consuming enzymes correlated well with sensitivity to NAMPT inhibition.

In order to investigate the effect of niacin on the antiproliferative effect of NAMPT inhibition across the cell panel, we further analyzed the cell sensitivity in the presence of niacin. Cells with a functional Preiss-Handler pathway can generate NAD+ from niacin, independent of NAMPT. We found that the antiproliferative effect of Cmpd1 was neutralized by niacin in 60% of the analyzed cells. The mRNA levels of nicotinate phosphoribosyltransferase 1 (NAPRT1), a central enzyme of the Preiss-Haendler pathway, predicted well the niacin rescue status of the cells. In vivo, niacin supplementation led to an at least 10-fold increase in the maximum tolerated dose of Cmpd1 in mice. Antitumor efficacy of Cmpd1 was abolished by niacin supplementation in xenografts derived from NAPRT1 expressing cells, but not in NAPRT1-deficient models. These data demonstrate that the therapeutic index of NAMPT inhibitors may be increased in NAPRT1-deficient tumors by niacin supplementation.

Citation Format: Maria Quanz, Claudia Merz, Andreas Bernthaler, Stefan Kaulfuss, Anja Richter, Marcus Bauser, Andrea Haegebarth. Pharmacological characterization of a novel potent nicotinamide phosphoribosyltransferase (NAMPT) inhibitor with robust in vivo efficacy and increased therapeutic index with niacin supplementation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1049.

Behavior of organophosphates and hydrophilic ethers during bank filtration and their potential application as organic tracers. A field study from the Oderbruch, Germany

The behavior of organophosphates and ethers during riverbank filtration and groundwater flow was assessed to determine their suitability as organic tracers. Four sampling campaigns were conducted at the Oderbruch polder, Germany to establish the presence of chlorinated flame retardants (TCEP, TCPP, TDCP), non-chlorinated plasticizers (TBEP, TiBP, TnBP), and hydrophilic ethers (1,4-dioxane, monoglyme, diglyme, triglyme, tetraglyme) in the Oder River, main drainage ditch, and anoxic aquifer. Selected parameters were measured in order to determine the hydro-chemical composition of both, river water and groundwater. The results of the study confirm that organophosphates (OPs) are more readily attenuated during bank filtration compared to ethers. Both in the river and the groundwater, TCPP was the most abundant OP with concentrations in the main drainage ditch ranging between 105 and 958 ng L(-1). 1,4-dioxane, triglyme, and tetraglyme demonstrated persistent behavior during bank filtration and in the anoxic groundwater. In the drainage ditch concentrations of 1,4-dioxane, triglyme, and tetraglyme ranged between 1090 and 1467 ng L(-1), 37 and 149 ng L(-1), and 496 and 1403 ng L(-1), respectively. A positive correlation was found for the inorganic tracer chloride with 1,4-dioxane and tetraglyme. These results confirm the possible application of these ethers as environmental organic tracers. Both inorganic and organic compounds showed temporal variability in the surface- and groundwater. Discharge of the river water, concentrations of analytes at the time of infiltration and attenuation were identified as factors influencing the variable amounts of the analytes in the surface and groundwater. These findings are also of great importance for the production of drinking water via bank filtration and natural and artificial groundwater recharge as the physicochemical properties of ethers create challenges in their removal.

Evaluation of activity and combination strategies with the microtubule-targeting drug sagopilone in breast cancer cell lines

Sagopilone, a fully synthetic epothilone, is a microtubule-stabilizing agent optimized for high in vitro and in vivo activity against a broad range of tumor models, including those resistant to paclitaxel and other systemic treatments. Sagopilone development is accompanied by translational research studies to evaluate the molecular mode of action, to recognize mechanisms leading to resistance, to identify predictive response biomarkers, and to establish a rationale for combination with different therapies. Here, we profiled sagopilone activity in breast cancer cell lines. To analyze the mechanisms of mitotic arrest and apoptosis and to identify additional targets and biomarkers, an siRNA-based RNAi drug modifier screen interrogating 300 genes was performed in four cancer cell lines. Defects of the spindle assembly checkpoint (SAC) were identified to cause resistance against sagopilone-induced mitotic arrest and apoptosis. Potential biomarkers for resistance could therefore be functional defects like polymorphisms or mutations in the SAC, particularly in the central SAC kinase BUB1B. Moreover, chromosomal heterogeneity and polyploidy are also potential biomarkers of sagopilone resistance since they imply an increased tolerance for aberrant mitosis. RNAi screening further demonstrated that the sagopilone-induced mitotic arrest can be enhanced by concomitant inhibition of mitotic kinesins, thus suggesting a potential combination therapy of sagopilone with a KIF2C (MCAK) kinesin inhibitor. However, the combination of sagopilone and inhibition of the prophase kinesin KIF11 (EG5) is antagonistic, indicating that the kinesin inhibitor has to be highly specific to bring about the required therapeutic benefit.

Inhibition of the IL-2-inducible tyrosine kinase (Itk) activity: a new concept for the therapy of inflammatory skin diseases

T-cell-mediated processes play an essential role in the pathogenesis of several inflammatory skin diseases such as atopic dermatitis, allergic contact dermatitis and psoriasis. The aim of this study was to investigate the role of the IL-2-inducible tyrosine kinase (Itk), an enzyme acting downstream of the T-cell receptor (TCR), in T-cell-dependent skin inflammation using three approaches. Itk knockout mice display significantly reduced inflammatory symptoms in mouse models of acute and subacute contact hypersensitivity (CHS) reactions. Systemic administration of a novel small molecule Itk inhibitor, Compound 44, created by chemical optimization of an initial high-throughput screening hit, inhibited Itk's activity with an IC50 in the nanomolar range. Compound 44 substantially reduced proinflammatory immune responses in vitro and in vivo after systemic administration in two acute CHS models. In addition, our data reveal that human Itk, comparable to its murine homologue, is expressed mainly in T cells and is increased in lesional skin from patients with atopic dermatitis and allergic contact dermatitis. Finally, silencing of Itk by RNA interference in primary human T cells efficiently blocks TCR-induced lymphokine secretion. In conclusion, Itk represents an interesting new target for the therapy of T-cell-mediated inflammatory skin diseases.

RNA interference-mediated gene silencing in murine T cells: in vitro and in vivo validation of proinflammatory target genes

Background

T cells play a central role in many inflammatory diseases, hence the identification and validation of T cell-specific target genes will increase the understanding of T cell function in pathologic inflammatory situations. RNA interference (RNAi), with its ability to induce specific gene silencing in mammalian cells, represents a powerful technology to investigate and validate the function of pharmaceutical target genes in vitro and in vivo. The aim of the present study was to systematically explore RNAi-mediated gene-silencing of known T cell-specific model signaling molecules in primary murine T cells in vitro and in vivo.

Results

We demonstrate that siRNA delivery and subsequent silencing of T cell specific genes is substantially increased, if murine T cells were activated prior siRNA transfection. Silencing of ZAP70, p56Lck as well as PLC-γ1 protein expression resulted in impaired function of T cells in vitro. Furthermore, delayed type hypersensitivity (DTH) was ameliorated in vivo after adoptive transfer of ZAP70-silenced T cells.

Coclusion

The combination of RNAi-mediated gene silencing and adoptive transfer of gene-silenced T cells, thus, may allow the identification and analysis of T cell-specific targets for therapeutic intervention. Additionally, this model system may represent an alternative to conventional time consuming and cost intensive gene targeting approaches.

Association of polymorphisms in the mannose-binding lectin gene and pulmonary morbidity in preterm infants

Deficiency in the collectin mannose-binding lectin (MBL) increases the risk for pulmonary and systemic infections and its complications in children and adults. The aim of this prospective cohort study was to determine the genetic association of sequence variations within the MBL gene with systemic infections and pulmonary short- and long-term complications in preterm infants below 32 weeks gestational age (GA). Three single-nucleotide polymorphisms (SNPs) in the coding region and one SNP in the promotor region of MBL2 were genotyped by direct sequencing and with sequence-specific probes in 284 newborn infants <32 weeks GA. Clinical variables were comprehensively monitored. An association was found between two SNPs and the development of bronchopulmonary dysplasia (BPD), defined as persistent oxygen requirement at 36 weeks postmenstrual age, adjusting for covariates GA, grade of respiratory distress syndrome and days on mechanical ventilation (rs1800450 (exon 1 at codon 54, B variant): odds ratio dominant model (OR)=3.59, 95% confidence interval (CI)=1.62-7.98; rs7096206 (-221, X variant): OR=2.40, 95% CI=1.16-4.96). Haplotype analyses confirmed the association to BPD, and a single haplotype (frequency 56%) including all SNPs in their wild-type form showed a negative association with the development of BPD. We detected no association between the MBL gene variations and the development of early-onset infections or further pulmonary complications. Frequent variants of the MBL gene, leading to low MBL concentrations, are associated with the diagnosis of BPD in preterm infants. This provides a basis for potential therapeutic options and further genetic and proteomic analysis of the function of MBL in the resistance against pulmonary long-term complications in preterm infants.

Differentiation of vascular birthmarks by MR imaging. An investigation of hemangiomas, venous and lymphatic malformations

PURPOSE

To evaluate the use of MR imaging using standard sequences in the differentiation of common vascular birthmarks of soft tissues in childhood.

MATERIAL AND METHODS

Forty-three lesions in 37 children (median age 33 months) with hemangiomas (n=25), venous (n=8) and lymphatic (n=10) malformations were retrospectively studied. Images were obtained with a 0.2 T and a 1.5 T MR unit, using T1-weighted spin-echo, T2-weighted turbo spin-echo and turbo STIR sequences. In addition, 19 contrast studies were evaluated. Signal intensities and morphological characteristics were analyzed.

RESULTS

All hemangiomas were hyperintense in T2-weighted, and mostly (22/25) isointense compared to the surrounding skeletal muscle in T1-weighted images. The lesions were homogeneous or mildly inhomogeneous and well defined. Venous and lymphatic malformations showed similar patterns. Contrary to other lesions, no vessels or lobular architecture were detectable and contrast enhancement was absent in lymphatic malformations.

CONCLUSION

A reliable differentiation between hemangiomas, venous and lymphatic malformations in childhood is not possible by standard MR sequences alone. Contrast media may be helpful as lymphatic malformations show no contrast enhancement. The main role of MR imaging is to determine the local extent or infiltration of deeper tissue layers and narrow the differential diagnosis of other soft tissue tumors.

Comparison between a screen-film system and a selenium radiography system. An ROC study using simulated thoracic lesions

RATIONALE AND OBJECTIVES

To evaluate the diagnostic image quality of the hard copies of a commercially available selenium detector-based computed radiography system compared to that of a conventional screen-film system.

METHODS

Ten radiographs of an anthropomorphic chest phantom with simulated nodular and linear-reticular lesions were produced using either system. Each radiograph was subdivided into 15 fields containing zero lesions, one nodular lesion, one linear-reticular lesion, or both lesions. The total of 150 fields for each modality was reviewed by six radiologists, and receiver operating analysis was performed.

RESULTS

The conventional screen-film system performed significantly better for nodular lesions, whereas no statistically significant difference was found between the detection rates of both systems for linear-reticular lesions.

CONCLUSIONS

The better detection of nodules with the dedicated selenium detector can be explained by the higher dynamic range of the system. Detection of linear-reticular lesions was slightly but not significantly better with the screen-film system, but the detection rate of the selenium detector might be further improved with a different image processing technique.

Does intraoperative blood loss affect antibiotic serum and tissue concentrations?

OBJECTIVE

To determine the effect of intraoperative blood loss on prophylactic cefazolin and gentamicin serum and tissue concentrations.

DESIGN

A prospective study of elective spinal instrumentation surgical procedures with an expected large blood loss.

SETTING

Tertiary care, inner-city university hospital.

PATIENTS

Eleven adult patients who underwent an elective surgical procedure that involved spinal instrumentation.

INTERVENTION

Standard perioperative administration of a combination of cefazolin and gentamicin. Serum and tissue samples were obtained consecutively throughout the surgical procedure.

MAIN OUTCOME MEASURES

The effect of intraoperative blood loss on serum and tissue cefazolin and gentamicin concentrations and their pharmacokinetics.

RESULTS

At the time of the incision, serum cefazolin concentrations were greater than tissue concentrations (P = .07). A mean dose of 1.8-mg/kg gentamicin yielded low or nontherapeutic serum and tissue gentamicin concentrations. Cefazolin and gentamicin were eliminated from the tissue compartment slower than from the serum compartment (P < .03), while the half-life of cefazolin was significantly (P = .06) longer in the tissue compartment. The volume of distribution of cefazolin was normal (ie, 12.5 L), while the volume of distribution of gentamicin was 5-fold greater than expected. At 60 minutes after the incision, blood loss correlated with cefazolin tissue concentrations (r = -0.66, P = .05). Blood loss correlated with the change in tissue antibiotic concentrations for cefazolin (r = 0.73, P = .04). In addition, the clearance of gentamicin from the tissues correlated with blood loss (r = 0.82, P = .01).

CONCLUSIONS

Based on measured pharmacokinetic values, additional doses of cefazolin should be administered when the operation exceeds 3 hours and blood loss is greater than 1500 mL. Doses of gentamicin greater than 1.8 mg/kg should be administered more than 30 minutes prior to the surgical incision.

Clostridium difficile colitis: an efficient clinical approach to diagnosis

OBJECTIVE

To define clinical and laboratory variables that suggest the presence of Clostridium difficile colitis and to establish the number of stool specimens needed to reasonably exclude the diagnosis of C. difficile colitis.

DESIGN

Prospective study of consecutive inpatients whose stool specimens were sent to be evaluated for the presence of C. difficile toxin.

SETTING

University teaching hospital.

PATIENTS

268 hospital inpatients in medical, surgical, and gynecology units.

MEASUREMENTS

Structured history and physical examination; detection of C. difficile toxin by cytotoxin tissue-culture assay with anti-C. difficile antiserum neutralization and by enzyme-linked immunoassay (EIA) for C. difficile toxins A and B; and detection of fecal leukocytes by microscopic examination and by latex agglutination lactoferrin assay.

RESULTS

43 of 268 consecutive inpatients were positive for C. difficile toxin by EIA or tissue-culture assay. Although toxin was detected by EIA alone in 39 of the 43 patients, it was detected in an additional 4 patients (10%) by tissue-culture assay alone. Univariate and multivariate logistic regression analysis showed that the following clinical and laboratory features were associated with C. difficile toxin positivity: the onset of diarrhea 6 or more days after the administration of antibiotics (odds ratio, 1.38 [95% CI, 1.10 to 3.79]); hospital stay longer than 15 days (odds ratio, 1.33 [CI, 1.09 to 3.95]); the presence of fecal leukocytes determined by microscopy (odds ratio, 2.39 [CI, 1.05 to 5.42]) or lactoferrin assay (odds ratio, 3.74 [CI, 1.80 to 7.76]); the presence of semiformed (as opposed to watery) stools (odds ratio, 2.33 [CI, 1.10 to 4.90]); and cephalosporin use (odds ratio, 2.36 [CI, 1.10 to 5.09]). Toxin-positive patients were no more likely than controls to have had fever, abdominal pain or cramps, leukocytosis, green-colored diarrhea, or blood in the stool or to have received clindamycin or penicillin derivatives. Of the 43 patients with C. difficile toxin, 34 (79%) had positive results for the toxin on the first stool specimen, 5 (cumulative, 91%) had positive results on the second specimen, and 4 had positive results on the third specimen. Overall, the negative predictive value of the first stool specimen was 97%. All patients who had two or more clinical or laboratory predictors were diagnosed with C. difficile disease when either the first or the second stool specimen was positive for toxin.

CONCLUSIONS

Clinicians at the bedside can use readily available clinical and laboratory information to decide which patients are likely to have C. difficile disease and when it is appropriate and useful to order specific diagnostic tests for C. difficile toxin. Such data are also useful in determining the number of stool samples that reasonably excludes the diagnosis of C. difficile colitis.