FBP1-Altered Carbohydrate Metabolism Reduces Leukemic Viability through Activating P53 and Modulating the Mitochondrial Quality Control System In Vitro.

Acute myeloid leukemia (AML)-the most frequent form of adult blood cancer-is characterized by heterogeneous mechanisms and disease progression. Developing an effective therapeutic strategy that targets metabolic homeostasis and energy production in immature leukemic cells (blasts) is essential for overcoming relapse and improving the prognosis of AML patients with different subtypes. With respect to metabolic regulation, fructose-1,6-bisphosphatase 1 (FBP1) is a gluconeogenic enzyme that is vital to carbohydrate metabolism, since gluconeogenesis is the central pathway for the production of important metabolites and energy necessary to maintain normal cellular activities. Beyond its catalytic activity, FBP1 inhibits aerobic glycolysis-known as the "Warburg effect"-in cancer cells. Importantly, while downregulation of FBP1 is associated with carcinogenesis in major human organs, restoration of FBP1 in cancer cells promotes apoptosis and prevents disease progression in solid tumors. Recently, our large-scale sequencing analyses revealed FBP1 as a novel inducible therapeutic target among 17,757 vitamin-D-responsive genes in MV4-11 or MOLM-14 blasts in vitro, both of which were derived from AML patients with FLT3 mutations. To investigate FBP1's anti-leukemic function in this study, we generated a new AML cell line through lentiviral overexpression of an FBP1 transgene in vitro (named FBP1-MV4-11). Results showed that FBP1-MV4-11 blasts are more prone to apoptosis than MV4-11 blasts. Mechanistically, FBP1-MV4-11 blasts have significantly increased gene and protein expression of P53, as confirmed by the P53 promoter assay in vitro. However, enhanced cell death and reduced proliferation of FBP1-MV4-11 blasts could be reversed by supplementation with post-glycolytic metabolites in vitro. Additionally, FBP1-MV4-11 blasts were found to have impaired mitochondrial homeostasis through reduced cytochrome c oxidase subunit 2 (COX2 or MT-CO2) and upregulated PTEN-induced kinase (PINK1) expressions. In summary, this is the first in vitro evidence that FBP1-altered carbohydrate metabolism and FBP1-activated P53 can initiate leukemic death by activating mitochondrial reprogramming in AML blasts, supporting the clinical potential of FBP1-based therapies for AML-like cancers.

Effects of green tea epigallocatechin-3-gallate on transcription factors regulating expression of FLT3.

PURPOSE: In our previous paper we previously reported that epigallocatechin-3-gallate (EGCG) inhibits FLT3 expression in cell lines harboring FLT3 mutations. In this research, we carried on to investigate the influence of EGCG on FLT3 promoter activity and FLT3 transcription. Methods The effect of EGCG on the mRNA expression of flt3 and flt3-promoter activity was evaluated using semiquantitative reverse transcription-PCR and luciferase reporter assay. The gene expression profiling analysis was done for detecting the effect of EGCG on flt3-transcription factors. Then, the protein level of C-MyB was obsvered using western blot analysis. RESULTS: The results showed that EGCG reduced the transcription level of FLT3 by suppressing its promoter activity. By doing gene expression profile analysis in MOLM-13 cells established from acute monocytic leukemia patient with two mutations within FLT3 EXON 14 in a time-dependent manner, we found that the expression of mRNA of FLT3 was first observed to downregulate at 6 h together with the decreasing of Homeobox A9 (HOXA9) transcription factor after EGCG treatment. The changing of C/EBPα expression was found at 8 h. Interestingly, the reducing mRNA of c-Myb by EGCG was observed at 4 h, earlier than FLT3 was downregulated. There was no change in Meis Homeobox 1 (Meis1) by EGCG. We also found the protein level c-Myb was inhibited by EGCG in MOLM-13 and MOLM-14 cells after treating these cells with 60µM of EGCG for 8 h. CONCLUSION: This data indicated the involvement of transcription factors in controlling the expression of FLT3 by EGCG.

Isoliquiritigenin, an Orally Available Natural FLT3 Inhibitor from Licorice, Exhibits Selective Anti-Acute Myeloid Leukemia Efficacy In Vitro and In Vivo.

Licorice is a medicinal herb widely used to treat inflammation-related diseases in China. Isoliquiritigenin (ISL) is an important constituent of licorice and possesses multiple bioactivities. In this study, we examined the selective anti-AML (acute myeloid leukemia) property of ISL via targeting FMS-like tyrosine kinase-3 (FLT3), a certified valid target for treating AML. In vitro, ISL potently inhibited FLT3 kinase, with an IC50 value of 115.1 ± 4.2 nM, and selectively inhibited the proliferation of FLT3-internal tandem duplication (FLT3-ITD) or FLT3-ITD/F691L mutant AML cells. Moreover, it showed very weak activity toward other tested cell lines or kinases. Western blot immunoassay revealed that ISL significantly inhibited the activation of FLT3/Erk1/2/signal transducer and activator of transcription 5 (STAT5) signal in AML cells. Meanwhile, a molecular docking study indicated that ISL could stably form aromatic interactions and hydrogen bonds within the kinase domain of FLT3. In vivo, oral administration of ISL significantly inhibited the MV4-11 flank tumor growth and prolonged survival in the bone marrow transplant model via decreasing the expression of Ki67 and inducing apoptosis. Taken together, the present study identified a novel function of ISL as a selective FLT3 inhibitor. ISL could also be a potential natural bioactive compound for treating AML with FLT3-ITD or FLT3-ITD/F691L mutations. Thus, ISL and licorice might possess potential therapeutic effects for treating AML, providing a new strategy for anti-AML.

Discovery of N-(4-(6-Acetamidopyrimidin-4-yloxy)phenyl)-2-(2-(trifluoromethyl)phenyl)acetamide (CHMFL-FLT3-335) as a Potent FMS-like Tyrosine Kinase 3 Internal Tandem Duplication (FLT3-ITD) Mutant Selective Inhibitor for Acute Myeloid Leukemia.

Most of the current FMS-like tyrosine kinase 3 (FLT3) inhibitors lack selectivity between FLT3 kinase and cKIT kinase as well as the FLT3 wt and internal tandem duplication (ITD) mutants. We report a new compound 27, which displays GI50 values of 30-80 nM against different ITD mutants and achieves selectivity over both FLT3 wt (8-fold) and cKIT kinase in the transformed BaF3 cells (>300-fold). 27 potently inhibits the proliferation of the FLT3-ITD-positive acute myeloid leukemia cancer lines through suppression of the phosphorylation of FLT3 kinase and downstream signaling pathways, induction of apoptosis, and arresting the cell cycle into the G0/G1 phase. 27 also displays potent antiproliferative effect against FLT3-ITD-positive patient primary cells, whereas it does not apparently affect FLT3 wt primary cells. In addition, it also exhibits a good therapeutic window to PBMC compared to PKC412. In the in vivo studies, 27 demonstrates favorable PK profiles and suppresses the tumor growth in the MV4-11 cell inoculated mouse xenograft model.

Incubation of Immune Cell Grafts With MAX.16H5 IgG1 Anti-Human CD4 Antibody Prolonged Survival After Hematopoietic Stem Cell Transplantation in a Mouse Model for Fms Like Tyrosine Kinase 3 Positive Acute Myeloid Leukemia.

Despite the constant development of innovative therapeutic options for hematological malignancies, the gold-standard therapy regimen for curative treatment often includes allogeneic hematopoietic stem cell transplantation (HSCT). The graft-vs.-leukemia effect (GVL) is one of the main therapeutic goals that arises from HSCT. On the other hand, graft-vs.-host disease (GVHD) is still one of the main and most serious complications following allogeneic HSCT. In acute myeloid leukemia (AML), HSCT together with high-dose chemotherapy is used as a treatment option. An aggressive progression of the disease, a decreased response to treatment, and a poor prognosis are connected to internal tandem duplication (ITD) mutations in the Fms like tyrosine kinase 3 (FLT3) gene, which affects around 30% of AML patients. In this study, C3H/HeN mice received an allogeneic graft together with 32D-FLT3ITD AML cells to induce acute GVHD and GVL. It was examined if pre-incubation of the graft with the anti-human cluster of differentiation (CD) 4 antibody MAX.16H5 IgG1 prevented the development of GVHD and whether the graft function was impaired. Animals receiving grafts pre-incubated with the antibody together with FLT3ITD AML cells survived significantly longer than mice receiving untreated grafts. The observed prolonged survival due to MAX.16H5 incubation of immune cell grafts prior to transplantation may allow an extended application of additional targeted strategies in the treatment of AML.

Sorafenib as a Salvage Therapy in FLT3-ITD Negative Relapse/ Refractory Acute Myeloid Leukemia.

BACKGROUND: Multi-kinase inhibitor sorafenib showed dramatic effects in acute myeloid leukemia (AML) cells harboring fms-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation. However, FLT3-ITD mutation only occurs in 25% of AML cases. The therapeutic effects of sorafenib in AML patients without FLT3-ITD are still in need of further investigation. METHODS: A young AML patient with central nervous system (CNS) relapse was treated with sorafenib combined with chemotherapy. Another patient with refractory AML arising form chronic myelomonocytic leukemia (CMML) was treated with sorafenib monotherapy. Spinal and cranial magnetic resonance imaging (MRI), minimal residual disease (MRD) and peripheral blood cell count were monitored to evaluate disease status. RESULTS: The patient with CNS relapse exhibited significant shrink of tumor volume. The other patient with refractory AML achieved hematological improvements. CONCLUSION: These two cases suggested that sorafenib might be utilized as a potent salvage therapy for some refractory/relapsed AML patients without the FLT3-ITD mutation.

Glutaminolysis is a metabolic dependency in FLT3ITD acute myeloid leukemia unmasked by FLT3 tyrosine kinase inhibition.

FLT3 internal tandem duplication (FLT3ITD) mutations are common in acute myeloid leukemia (AML) associated with poor patient prognosis. Although new-generation FLT3 tyrosine kinase inhibitors (TKI) have shown promising results, the outcome of FLT3ITD AML patients remains poor and demands the identification of novel, specific, and validated therapeutic targets for this highly aggressive AML subtype. Utilizing an unbiased genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screen, we identify GLS, the first enzyme in glutamine metabolism, as synthetically lethal with FLT3-TKI treatment. Using complementary metabolomic and gene-expression analysis, we demonstrate that glutamine metabolism, through its ability to support both mitochondrial function and cellular redox metabolism, becomes a metabolic dependency of FLT3ITD AML, specifically unmasked by FLT3-TKI treatment. We extend these findings to AML subtypes driven by other tyrosine kinase (TK) activating mutations and validate the role of GLS as a clinically actionable therapeutic target in both primary AML and in vivo models. Our work highlights the role of metabolic adaptations as a resistance mechanism to several TKI and suggests glutaminolysis as a therapeutically targetable vulnerability when combined with specific TKI in FLT3ITD and other TK activating mutation-driven leukemias.

Hypoxia-induced upregulation of BMX kinase mediates therapeutic resistance in acute myeloid leukemia.

Oncogenic addiction to the Fms-like tyrosine kinase 3 (FLT3) is a hallmark of acute myeloid leukemia (AML) that harbors the FLT3-internal tandem duplication (FLT3-ITD) mutation. While FLT3 inhibitors like sorafenib show initial therapeutic efficacy, resistance rapidly develops through mechanisms that are incompletely understood. Here, we used RNA-Seq-based analysis of patient leukemic cells and found that upregulation of the Tec family kinase BMX occurs during sorafenib resistance. This upregulation was recapitulated in an in vivo murine FLT3-ITD-positive (FLT3-ITD+) model of sorafenib resistance. Mechanistically, the antiangiogenic effects of sorafenib led to increased bone marrow hypoxia, which contributed to HIF-dependent BMX upregulation. In in vitro experiments, hypoxia-dependent BMX upregulation was observed in both AML and non-AML cell lines. Functional studies in human FLT3-ITD+ cell lines showed that BMX is part of a compensatory signaling mechanism that promotes AML cell survival during FLT3 inhibition. Taken together, our results demonstrate that hypoxia-dependent upregulation of BMX contributes to therapeutic resistance through a compensatory prosurvival signaling mechanism. These results also reveal the role of off-target drug effects on tumor microenvironment and development of acquired drug resistance. We propose that the bone marrow niche can be altered by anticancer therapeutics, resulting in drug resistance through cell-nonautonomous microenvironment-dependent effects.

In vitro and in vivo anticancer activity of 2-acetyl-benzylamine isolated from Adhatoda vasica L. leaves.

One of the important aims of drug discovery for cancer is to find therapeutic agents from natural products that are effective and safe for cancer treatment. In the current study, an alkaloid, 2-acetyl-benzylamine, isolated from Adhatoda vasica, was screened for potent anticancer properties against leukemia cells. We used seven different types of leukemia cells such as CEM, NB-4, MOLM-14, Jurkat, IM-9, K562 and HL-60 for cytotoxic studies. 2-acetyl-benzylamine showed significant cytotoxic properties against MOLM-14 and NB-4 cells with IC50 values of 0.40 and 0.39mM at 24h when compared to other tested cells, respectively. Apoptosis was confirmed by annexin V-FITC/PI kit using flow cytometry and confocal microscope in MOLM-14 and NB-4 cells. In addition, 2-acetyl-benzylamine induced cell cycle arrest at G2/M phase in MOLM-14 cells and G0/G1 phase in NB-4 cells. Apoptosis mechanism was confirmed by RT-PCR and Western blot analysis. Treatment with 2-acetyl-benzylamine decreased the Bcl-2 activity and increased the Bax expression; cytochrome c was released and caspases-3 was activated in MOLM-14 and NB-4 cells. Besides, 2-acetyl-benzylamine inhibited the expression of JAK2/STAT3 in MOLM-14 and NB-4 cells. In vivo administration of 2-acetyl-benzylamine inhibited the growth of MOLM-14 cells in xenograft mice model. Molecular docking study has been performed to investigate the binding mode and to estimate the binding energy of 2-acetyl-benzylamine with the active site of JAK-2, AKT1, FLT3 and Bcl-2. The above findings proved that 2-acetyl-benzylamine could be developed as a potential therapeutic agent against cancer.

FLT3 Inhibitors in Acute Myeloid Leukemia: Current Status and Future Directions.

The receptor tyrosine kinase fms-like tyrosine kinase 3 (FLT3), involved in regulating survival, proliferation, and differentiation of hematopoietic stem/progenitor cells, is expressed on acute myeloid leukemia (AML) cells in most patients. Mutations of FLT3 resulting in constitutive signaling are common in AML, including internal tandem duplication (ITD) in the juxtamembrane domain in 25% of patients and point mutations in the tyrosine kinase domain in 5%. Patients with AML with FLT3-ITD have a high relapse rate and short relapse-free and overall survival after chemotherapy and after transplant. A number of inhibitors of FLT3 signaling have been identified and are in clinical trials, both alone and with chemotherapy, with the goal of improving clinical outcomes in patients with AML with FLT3 mutations. While inhibitor monotherapy produces clinical responses, they are usually incomplete and transient, and resistance develops rapidly. Diverse combination therapies have been suggested to potentiate the efficacy of FLT3 inhibitors and to prevent development of resistance or overcome resistance. Combinations with epigenetic therapies, proteasome inhibitors, downstream kinase inhibitors, phosphatase activators, and other drugs that alter signaling are being explored. This review summarizes the current status of translational and clinical research on FLT3 inhibitors in AML, and discusses novel combination approaches. Mol Cancer Ther; 16(6); 991-1001. ©2017 AACR.

Chronic myelomonocytic leukemia with double-mutations in DNMT3A and FLT3-ITD treated with decitabine and sorafenib.

Chronic myelomonocytic leukemia (CMML) is a heterogeneous neoplastic hematologic disorder with worse overall survival. Half of CMML have mutations, but case with concomitant mutations of DNA methyltransferase 3A (DNMT3A) and Internal tandem duplications of the juxtamembrane domain of FLT3 (FLT3-ITD) in CMML was not reported before. We reported a 51-year-old man who had CMML with concomitant mutations in DNMT3A and FLT3-ITD.The patient received decitabine and sorafenib combined treatment. In this report, we reviewed DNMT3A mutation and FLT3 mutation, and we reviewed treatment of decitabine and sorafenib. This report is significant. First: This is the first report on CMML with double-mutations of DNMT3A and FLT3-ITD. Second: It shows the importance of targeted drug in combined treatment of CMML.

Homoharringtonine (omacetaxine mepesuccinate) as an adjunct for FLT3-ITD acute myeloid leukemia.

An in vitro drug-screening platform on patient samples was developed and validated to design personalized treatment for relapsed/refractory acute myeloid leukemia (AML). Unbiased clustering and correlation showed that homoharringtonine (HHT), also known as omacetaxine mepesuccinate, exhibited preferential antileukemia effect against AML carrying internal tandem duplication of fms-like tyrosine kinase 3 (FLT3-ITD). It worked synergistically with FLT3 inhibitors to suppress leukemia growth in vitro and in xenograft mouse models. Mechanistically, the effect was mediated by protein synthesis inhibition and reduction of short-lived proteins, including total and phosphorylated forms of FLT3 and its downstream signaling proteins. A phase 2 clinical trial of sorafenib and HHT combination treatment in FLT3-ITD AML patients resulted in complete remission (true or with insufficient hematological recovery) in 20 of 24 patients (83.3%), reduction of ITD allelic burden, and median leukemia-free and overall survivals of 12 and 33 weeks. The regimen has successfully bridged five patients to allogeneic hematopoietic stem cell transplantation and was well tolerated in patients unfit for conventional chemotherapy, including elderly and heavily pretreated patients. This study validated the principle and clinical relevance of in vitro drug testing and identified an improved treatment for FLT3-ITD AML. The results provided the foundation for phase 2/3 clinical trials to ascertain the clinical efficacy of FLT3 inhibitors and HHT in combination.

[Clinical Efficacy of Sorafenib Combined with Low Dose Cytarabine for Treating Patients with FLT3+ Relapsed and Refractory Acute Myeloid Leukemia].

OBJECTIVE: To study the efficacy and safety of sorafenib combined with low dose cytarabine for treating patients with FLT3(+) relapsed and refractory acute myeloid leukemia (FLT3(+) RR-AML). METHODS: Seven patients with FLT3(+) RR-AML were treated with sorafenib and low dose cytarabine. The curative rate and adverse effects were observed in these patients. RESULTS: Out of 7 RR-AML patients after treatment, 5 patients achieved complete remission (CR), 2 patients achieved partial remission (PR), and the overall response rate (ORR) after one course of therapy was 100%. No severe bleeding, nausea, vomiting and other side effects were found in these patients. CONCLUSION: Sorafenib combined with low dose cytarabine can effectively induce the remission of FLT3(+) RR-AML patients, and is worth for further clinical trails to verify its safty and efficiency.

Decitabine and Sorafenib Therapy in FLT-3 ITD-Mutant Acute Myeloid Leukemia.

BACKGROUND: Acute myeloid leukemia (AML) characterized by Feline McDonough Sarcoma-like tyrosine kinase-3 (FLT-3) internal tandem duplication (ITD) mutations have poor outcomes. Treatment options are limited, because these mutations confer resistance to conventional chemotherapy. FLT-3 inhibitors such as sorafenib have been studied as a single agent and in combination with conventional chemotherapy or azacytidine with fair responses. PATIENTS AND METHODS: Here we describe our preclinical and clinical experience with the combination of the DNA hypomethylating agent, decitabine and sorafenib for the treatment of FLT-3 ITD-mutant AML. RESULTS: In vitro treatment of the human FLT-3 ITD-mutant AML cell line, MV4-11, with both drugs significantly improved growth inhibition over single-agent therapy and resulted in synergistic antitumor effects (combination index < 1). A case series of 6 patients treated with off protocol combination of decitabine and sorafenib demonstrated overall responses in 5 patients (83%) with a median survival of 155 days. Four of the 5 patients (80%) with relapsed/refractory AML achieved complete responses with incomplete count recovery. The combination was also well tolerated. CONCLUSION: Further investigation is warranted to confirm these responses.

NFATc1 as a therapeutic target in FLT3-ITD-positive AML.

Internal tandem duplications (ITD) in the Fms-related tyrosine kinase 3 receptor (FLT3) are associated with a dismal prognosis in acute myeloid leukemia (AML). FLT3 inhibitors such as sorafenib may improve outcome, but only few patients display long-term responses, prompting the search for underlying resistance mechanisms and therapeutic strategies to overcome them. Here we identified that the nuclear factor of activated T cells, NFATc1, is frequently overexpressed in FLT3-ITD-positive (FLT3-ITD+) AML. NFATc1 knockdown using inducible short hairpin RNA or pharmacological NFAT inhibition with cyclosporine A (CsA) or VIVIT significantly augmented sorafenib-induced apoptosis of FLT3-ITD+ cells. CsA also potently overcame sorafenib resistance in FLT3-ITD+ cell lines and primary AML. Vice versa, de novo expression of a constitutively nuclear NFATc1-mutant mediated instant and robust sorafenib resistance in vitro. Intriguingly, FLT3-ITD+ AML patients (n=26) who received CsA as part of their rescue chemotherapy displayed a superior outcome when compared with wild-type FLT3 (FLT3-WT) AML patients. Our data unveil NFATc1 as a novel mediator of sorafenib resistance in FLT3-ITD+ AML. CsA counteracts sorafenib resistance and may improve treatment outcome in AML by means of inhibiting NFAT.

Tyrosine kinase inhibition in leukemia induces an altered metabolic state sensitive to mitochondrial perturbations.

PURPOSE: Although tyrosine kinase inhibitors (TKI) can be effective therapies for leukemia, they fail to fully eliminate leukemic cells and achieve durable remissions for many patients with advanced BCR-ABL(+) leukemias or acute myelogenous leukemia (AML). Through a large-scale synthetic lethal RNAi screen, we identified pyruvate dehydrogenase, the limiting enzyme for pyruvate entry into the mitochondrial tricarboxylic acid cycle, as critical for the survival of chronic myelogenous leukemia (CML) cells upon BCR-ABL inhibition. Here, we examined the role of mitochondrial metabolism in the survival of Ph(+) leukemia and AML upon TK inhibition. EXPERIMENTAL DESIGN: Ph(+) cancer cell lines, AML cell lines, leukemia xenografts, cord blood, and patient samples were examined. RESULTS: We showed that the mitochondrial ATP-synthase inhibitor oligomycin-A greatly sensitized leukemia cells to TKI in vitro. Surprisingly, oligomycin-A sensitized leukemia cells to BCR-ABL inhibition at concentrations of 100- to 1,000-fold below those required for inhibition of respiration. Oligomycin-A treatment rapidly led to mitochondrial membrane depolarization and reduced ATP levels, and promoted superoxide production and leukemia cell apoptosis when combined with TKI. Importantly, oligomycin-A enhanced elimination of BCR-ABL(+) leukemia cells by TKI in a mouse model and in primary blast crisis CML samples. Moreover, oligomycin-A also greatly potentiated the elimination of FLT3-dependent AML cells when combined with an FLT3 TKI, both in vitro and in vivo. CONCLUSIONS: TKI therapy in leukemia cells creates a novel metabolic state that is highly sensitive to particular mitochondrial perturbations. Targeting mitochondrial metabolism as an adjuvant therapy could therefore improve therapeutic responses to TKI for patients with BCR-ABL(+) and FLT3(ITD) leukemias.

Effectiveness and preclinical safety profile of doxycycline to be used "off-label" to induce therapeutic transgene expression in a phase I clinical trial for glioma.

Glioblastoma multiforme (GBM) is the most common malignant primary brain cancer in adults; it carries a dismal prognosis despite improvements in standard of care. We developed a combined gene therapy strategy using (1) herpes simplex type 1-thymidine kinase in conjunction with the cytotoxic prodrug ganciclovir to kill actively proliferating tumor cells and (2) doxycycline (DOX)-inducible Fms-like tyrosine kinase 3 ligand (Flt3L), an immune stimulatory molecule that induces anti-GBM immunity. As a prelude to a phase I clinical trial, we examined the efficacy and safety of this approach (Muhammad et al., 2010, 2012). In the present article, we investigated the efficacy and safety of the "off-label" use of the antibiotic DOX to turn on the high-capacity adenoviral vector (HC-Ad) encoding therapeutic Flt3L expression. DOX-inducible Flt3L expression in male Lewis rats was assessed using DOX doses of 30.8 mg/kg/day (low-DOX) or 46.2 mg/kg/day (high-DOX), which are allometrically equivalent (Voisin et al., 1990) to the human doses that are recommended for the treatment of infections: 200 or 300 mg/day. Naïve rats were intracranially injected with 1×10(9) viral particles of HC-Ad-TetOn-Flt3L, and expression of the therapeutic transgene, that is, Flt3L, was assessed using immunohistochemistry in brain sections after 2 weeks of DOX administration via oral gavage. The results show robust expression of Flt3L in the rat brain parenchyma in areas near the injection site in both the low-DOX and the high-DOX groups, suggesting that Flt3L will be expressed in human glioma patients at a DOX dose of 200 or 300 mg/day. These doses have been approved by the U.S. Food and Drug Administration to treat infections in humans and would thus be considered safe for an off-label use to treat GBM patients undergoing HC-Ad-mediated gene therapy in a phase I clinical trial.

Rapid induction of complete molecular remission by sequential therapy with LDAC and sorafenib in FLT3-ITD-positive patients unfit for intensive treatment: two cases and review of the literature.

Treatment of acute myeloid leukemia remains a therapeutic challenge. Even in younger patients with a low rate of co-morbidities less than 50% of patients can be cured. For older patients or patients with significant co-morbidities, the situation appears even worse. In patients not eligible for intensive treatment approaches - e.g. due to underlying medical conditions - therapeutic approaches remain almost exclusively palliative. However, even with less intense treatment approaches, temporary remission can be achieved and this contributes to prolonged survival and improved quality of life of the respective patient. Targeted therapies have been widely used as palliative treatment in- and outside clinical trials as single agents. Combination with low-dose cytarabine (LDAC) potentially improves remission rates and can be safely administered in an outpatient setting.Previous studies showed that additive hematologic toxicity of combinatory therapeutic approaches may arise from simultaneous treatment (e.g. chemotherapy plus targeted therapies). However, sequential therapies have already proven their feasibility in clinical trials. Here, we report two cases of rapid induction of complete molecular remission by sequential therapy with LDAC and sorafenib in patients unfit for intensive chemotherapy without significant long-term toxicity.