Epigenetic activation of O-linked ß-N-acetylglucosamine transferase overrides the differentiation blockage in acute leukemia.

BACKGROUND: Overriding the differentiation blockage in acute myeloid leukemia (AML) is the most successful mode-of-action in leukemia therapy - now curing the vast majority of patients with acute promyelocytic leukemia (APL) using all-trans retinoic acid (ATRA)-based regimens. Similar approaches in other leukemia subtypes, such as IDH1/2-mutated AML, are under active investigation. We herein present successful release of the differentiation blockage upon treatment with the natural (-)-Δ9-Tetrahydrocannabinol isomer dronabinol in vitro and in vivo. METHODS: Cellular maturation and differentiation were followed in two patients employing whole genome methylation profiling, proteome analyses, NGS deep sequencing and multispectral imaging flow cytometry. For functional studies lentiviral OGT knock-down in vitro and ex vivo cell models were created to evaluate proliferative, apoptotic and differentiating effects of OGT in acute leukemia. FINDINGS: In here, we provide molecular evidence that dronbinol is capable to override the differentiation blockage of acute leukemia blasts at the state of the leukemia-initiating clone. We further identify the O-linked ß-N-acetyl glucosamine (O-GlcNAc) transferase (OGT) to be crucial in this process. OGT is a master regulator enzyme adding O-GlcNAc to serine or threonine residues in a multitude of target proteins. Aberrant O-GlcNAc modification is implicated in pathologies of metabolic, neurodegenerative and autoimme diseases as well as cancers. We provide evidence that dronabinol induces transcription of OGT via epigenetic hypomethylation of the transcription start site (TSS). A lentiviral OGT-knock out approach proves the central role of OGT exerting antileukemic efficacy via a dual-mechanism of action: High concentrations of dronabinol result in induction of apoptosis, whereas lower concentrations drive cellular maturation. Most intriguingly, overriding of the differentiation blockage of acute leukemia blasts is validated in vivo following two patients treated with dronabinol. INTERPRETATION: In conclusion, we provide evidence for overcoming the differentiation blockage in acute leukemia in subentities beyond promyelocytic and IDH1/2-mutated leukemia and thereby identify O-GlcNAcylation as a novel (drugable) field for future leukemia research. FUNDING: Unrestricted grant support by the IZKF Program of the Medical Faculty Tübingen (MMS) and Brigitte Schlieben-Lange Program as well as the Margarete von Wrangell Program of the Ministry of Science, Research and the Arts, Baden-Württemberg, Germany (KKS) and Athene Program of the excellence initiative University of Tübingen (KKS).

A phase I pharmacokinetic study of matuzumab in combination with paclitaxel in patients with EGFR-expressing advanced non-small cell lung cancer.

Matuzumab is a humanized IgG1 EGFR monoclonal antibody. This phase I study investigated the tolerability, safety and pharmacokinetics (PK) of matuzumab in combination with paclitaxel in patients with EGFR-expressing advanced non-small cell lung cancer (NSCLC). Six dose levels/schedules of matuzumab were explored in combination with paclitaxel. Dose was escalated from 100 mg to 1,600 mg on a modified Fibonacci scheme according to the incidence of dose-limiting toxicity (DLT) over the first two cycles. DLT was assessed in patients who completed the first two treatment cycles or who stopped treatment because of a DLT during those cycles. Patients with non-progressive disease could then continue to receive study treatment for up to 6 months. The safety population comprised 44 patients, with DLT evaluable in 33. The maximum tolerated dose was not reached, with only one DLT reported at the 1,600 mg 3-weekly dose level. The most frequent grade 3/4 adverse events across all cycles were dyspnea (23 %) and neutropenia (11 %). Matuzumab exhibited non-linear PK, with accumulation after escalation and repeated dosing. Tumor growth control was seen in 15/44 (34 %) patients, including 5/9 (56 %) at the 800 mg weekly dose level. Matuzumab combined with paclitaxel was generally well tolerated in patients with advanced NSCLC. There was some evidence of anticancer activity in relation to the matuzumab 800 mg weekly dose.

FLT3 K663Q is a novel AML-associated oncogenic kinase: Determination of biochemical properties and sensitivity to Sunitinib (SU11248).

Somatic mutations of FLT3 resulting in constitutive kinase activation are the most common acquired genomic abnormality found in acute myeloid leukemia (AML). The majority of these mutations are internal tandem duplications (ITD) of the juxtamembrane region (JM). In addition, a minority of cases of AML are associated with mutation of the FLT3 activation loop (AL), typically involving codons D835 and/or I836. We hypothesized that other novel mutations of FLT3 could also contribute to leukemogenesis. We genotyped 109 cases of AML and identified two novel gain-of-function mutations. The first mutation, N841 H, is similar to previously described mutations involving amino-acid substitutions of codon 841. The other novel mutation, FLT3 K663Q, is the first AML-associated gain-of-function mutation located outside the JM and AL domains. Of note, this mutation was potently inhibited by Sunitinib (SU11248), a previously described FLT3 kinase inhibitor. Sunitinib reduced the proliferation and induced apoptosis of transformed Ba/F3 cells expressing FLT3 K663Q. The potency of Sunitinib against FLT3 K663Q was similar to its potency against FLT3 ITD mutations. We conclude that FLT3 mutations in AML can involve novel regions of the TK1. Future studies are needed to define the incidence and prognostic significance of FLT3 mutations outside the well-established JM and AL regions.

A phase I study of the humanized monoclonal anti-epidermal growth factor receptor (EGFR) antibody EMD 72000 (matuzumab) in combination with paclitaxel in patients with EGFR-positive advanced non-small-cell lung cancer (NSCLC).

BACKGROUND: Epidermal growth factor receptor (EGFR) is overexpressed in 80%-90% of non-small-cell lung cancer (NSCLC). Matuzumab, a humanized immunoglobulin G(1) (IgG(1)) anti-EGFR monoclonal antibody, blocks activation of EGFR. Paclitaxel and EGFR inhibitors have additive antitumour effects in vitro. This phase I study assessed the tolerability, pharmacokinetics and efficacy of the combination of matuzumab and paclitaxel in patients with advanced NSCLC. MATERIALS AND METHODS: Eighteen chemotherapy-naïve (n = 9) or pretreated (n = 9) patients with stage IIIB or IV EGFR-positive NSCLC received weekly doses of matuzumab (100, 200, 400 or 800 mg) followed by paclitaxel 175 mg/m(2) every 3 weeks. Toxicity was evaluated weekly and pharmacokinetics were measured during cycles 1 and 2. RESULTS: The maximum planned matuzumab dose of 800 mg was achieved without reaching the maximum tolerated dose. Grade 4 neutropenia occurred in one of three patients at 800 mg but resolved within 1 week; five additional patients treated with 800 mg had no dose-limiting toxicity (DLT). Grade 1/2 acneiform skin rash in 14 patients was the most frequent matuzumab-related side-effect. There were no higher-grade adverse events. Grade 2 toxicities included pruritus (n = 2), bronchospasm (n = 1), fissures (n = 1), abdominal pain (n = 1) and hot flushes (n = 1). Paclitaxel was discontinued in four patients due to allergic reactions. Coadministration of paclitaxel did not alter matuzumab pharmacokinetics. Responses occurred in four of 18 patients and included one complete response. CONCLUSIONS: Matuzumab doses up to 800 mg weekly with paclitaxel 175 mg/m(2) every 3 weeks are well tolerated, with no apparent drug interactions and with evidence of antitumor activity.

Efficacy of cytotoxic agents used in the treatment of testicular germ cell tumours under normoxic and hypoxic conditions in vitro.

Platinum-based chemotherapy is the main treatment element to achieve cure for patients with metastatic germ cell tumours. Drug resistance in testicular germ cell tumours (TGCTs) is rare and the reasons are not fully understood. While recent investigations have indicated decreased efficacy of chemotherapy in several tumour types under hypoxic conditions, this aspect has not been investigated in TGCTs so far. Furthermore, for cisplatin - the most active drug in this disease - controversial effects of hypoxia on cytotoxic efficacy have been reported. The relative efficacy of cytotoxic agents for the treatment of TGCT patients was studied in three different cell lines derived from human embryonal carcinomas (EC) in an in vitro hypoxia model. NT2, 2102 EP, and NCCIT were tested for their sensitivity towards cisplatin, etoposide, bleomycin, 4-OOH-ifosfamide, carboplatin, paclitaxel, gemcitabine, oxaliplatin, irinotecan, and mitomycin C under normoxic and hypoxic conditions using the MTT assay. Inhibitory concentrations IC(50) of the tested agents under both conditions were compared. Selected results were confirmed by flow-cytometric assessment of the apoptotic index. In all cells, doubling times were prolonged in hypoxia (NT2

Complete remission of third recurrence of acute myeloid leukemia after treatment with imatinib (STI-571).

We report the case of a 76-year old patient with third relapse of AML who was successfully treated with Imatinib. The decision to try Imatinib was guided by bright expression of c-kit on the patient's blasts. Treatment was well tolerated but the dose was reduced for pancytopenia and later stopped completely because of pneumonia. The patient recovered with i.v. antibiotics, antimycotics and s.c. G-CSF. Reevaluation of the bone marrow after the end of treatment demonstrated the absence of malignant blasts. Treatment with Imatinib was started again with the intention to prolong remission duration. During the following months peripheral blood counts stabilized in the normal range indicating that a fourth complete remission has been achieved in this patient. This is the first report demonstrating that Imatinib can induce complete remission in relapsed c-kit positive AML in an elderly patient. Prolonged cytopenia remains a considerable problem indicating that normal haematopoiesis is not completely independent of the signalling cascades inhibited by Imatinib. Nevertheless our report supports further study of this drug in c-kit positive AML.

Functional response of leukaemic blasts to stromal cell-derived factor-1 correlates with preferential expression of the chemokine receptor CXCR4 in acute myelomonocytic and lymphoblastic leukaemia.

The chemokine stromal cell-derived factor-1 (SDF-1) that is released by bone marrow (BM) stromal cells and contributes to stem cell homing may also play a role in the trafficking of leukaemic cells. We analysed SDF-1-induced intracellular calcium fluxes in leukaemic blasts from the peripheral blood of patients with newly diagnosed acute myeloid leukaemia (AML) and lymphoblastic leukaemia (B-lineage ALL), determined the effect of BM stromal cell-conditioned medium on in vitro transendothelial migration (TM) and measured expression of the SDF-1 receptor, CXCR4, by flow cytometry. AML FAB M1/2 blasts did not show calcium fluxes and TM was not stimulated. In myelomonocytic AML (M4/5), however, SDF-1 induced significant calcium fluxes and TM was increased twofold by the conditioned medium. M3 and M4 blasts with eosinophilia (M4eo) showed intermediate activity and M6 blasts showed no functional activity. In ALL, strong calcium fluxes and increased TM (2.5-fold) were observed. Accordingly, expression of CXCR4 was low in undifferentiated (M0) AML, myeloid (M1/2) AML and erythroid (M6) AML, but high [mean fluorescence (MF) > 50] in promyelocytic (M3) AML, myelomonocytic (M4/5) AML and B-lineage ALL. We conclude that, in AML, SDF-1 is preferentially active in myelomonocytic blasts as a result of differentiation-related expression of CXCR4. Functional activity of SDF-1 and high expression of CXCR4 in B-lineage ALL is in accordance with the previously described activity of SDF-1 in early B cells. SDF-1 may contribute to leukaemic marrow infiltration, as suggested by increased CXCR4 expression and migratory response in BM-derived blasts compared with circulating cells.