pyrimidinones and Brain-Neoplasms

Epithelioid glioblastoma multiforme (eGBM) is a rare and aggressive variant of glioblastoma multiforme (GBM) that predominantly affects younger patients and can be difficult to distinguish from other gliomas. Data on how patients with eGBM might be best treated are limited, although genomic analyses have shown that almost half of tumours harbour activating BRAF gene mutations. Here we present the case of a young female with BRAF V600E-mutant eGBM who had a prolonged response to targeted therapy with the BRAF and MEK1/2 inhibitors dabrafenib and trametinib. We review current knowledge about eGBM, including the emerging role for BRAF- ± MEK1/2- targeted therapy.

Topics: Antineoplastic Agents; Brain Neoplasms; Fatal Outcome; Female; Glioblastoma; Humans; Imidazoles; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Spinal Cord Neoplasms; Young Adult

Melanoma has a tendency to metastasize to the brain. The development of brain metastasis is observed in all mutational subgroups. Overall, they are associated with poor prognosis. They are also associated with pain, neurological deterioration and thus, have a major impact on patients' quality of life. Historically, effective palliation by systemic therapy has been rare. The availability of new therapeutic agents, however, heralds a significant improvement in management options for these patients.. The development of targeted therapies and immune activating checkpoint inhibitors with durable benefit has led to a treatment paradigm change. Several clinical studies in patients with metastatic melanoma have demonstrated improved survival compared to chemotherapy. Many of these studies however excluded patients with brain involvement. Antitumor activity in brain metastasis has now been observed with some agents; further positive data are emerging. Surgery and stereotactic radiotherapy are also used for local control of oligometastatic disease. We discuss the usefulness of the available systemic treatments for management of brain metastases and how these are integrated with local treatments to enable optimal palliation.. Advances in the treatment of melanoma are providing significant palliative benefit for patients with brain metastases. Further investigations are needed to determine optimal treatment combinations and sequences.

Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Brain Neoplasms; Combined Modality Therapy; Disease-Free Survival; Humans; Immunotherapy; Indoles; Melanoma; Molecular Targeted Therapy; Nivolumab; Prognosis; Programmed Cell Death 1 Receptor; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; Quality of Life; Skin Neoplasms; Sulfonamides; Vemurafenib

During the past several years, targeted therapies have significantly improved outcomes in advanced basal cell carcinoma, psoriasis, and metastatic melanoma. This article reviews how advances in our understanding of the molecular pathogenesis of these diseases led to the development of targeted therapies and how these therapies are improving outcomes. Research is ongoing to address continuing challenges of drug resistance, adverse effects, and how best to use the new medications.

Topics: Adult; Anilides; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Azetidines; Brain Neoplasms; Carcinoma, Basal Cell; Dermatologic Agents; Dermatology; Etanercept; Female; Humans; Imidazoles; Indoles; Interleukin-17; Male; Melanoma; Middle Aged; Molecular Targeted Therapy; Oximes; Piperidines; Proto-Oncogene Proteins B-raf; Psoriasis; Pyridines; Pyridones; Pyrimidinones; Skin Neoplasms; Sulfonamides; Tumor Necrosis Factor-alpha; Ustekinumab; Vemurafenib

Effective treatments are needed to improve outcomes for high-grade glioma and low-grade glioma. The activity and safety of dabrafenib plus trametinib were evaluated in adult patients with recurrent or progressive BRAF. This study is part of an ongoing open-label, single-arm, phase 2 Rare Oncology Agnostic Research (ROAR) basket trial at 27 community and academic cancer centres in 13 countries (Austria, Belgium, Canada, France, Germany, Italy, Japan, the Netherlands, Norway, South Korea, Spain, Sweden, and the USA). The study enrolled patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0, 1, or 2. Patients with BRAF. Between April 17, 2014, and July 25, 2018, 45 patients (31 with glioblastoma) were enrolled into the high-grade glioma cohort and 13 patients were enrolled into the low-grade glioma cohort. The results presented here are based on interim analysis 16 (data cutoff Sept 14, 2020). In the high-grade glioma cohort, median follow-up was 12·7 months (IQR 5·4-32·3) and 15 (33%; 95% CI 20-49) of 45 patients had an objective response by investigator assessment, including three complete responses and 12 partial responses. In the low-grade glioma cohort, median follow-up was 32·2 months (IQR 25·1-47·8). Nine (69%; 95% CI 39-91) of 13 patients had an objective response by investigator assessment, including one complete response, six partial responses, and two minor responses. Grade 3 or worse adverse events were reported in 31 (53%) patients, the most common being fatigue (five [9%]), decreased neutrophil count (five [9%]), headache (three [5%]), and neutropenia (three [5%]).. Dabrafenib plus trametinib showed clinically meaningful activity in patients with BRAF. Novartis.

Topics: Adolescent; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Female; Glioma; Humans; Imidazoles; Isocitrate Dehydrogenase; Male; Middle Aged; Mutation; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Young Adult

Trametinib is a MEK inhibitor with intracranial activity indicated for BRAF-mutant metastatic malignancies. Yet, the safety of trametinib concurrent with whole brain radiation therapy (WBRT) is unknown. We performed a single-institution, prospective, 3 + 3, phase I clinical trial to determine the maximum tolerated dose (MTD) of trametinib with WBRT.. Patients with brain metastases (BM) received daily trametinib for 28 days, starting 7 days prior to and continuing through WBRT (37.5 Gy/15 fractions). Dose levels (DL)1-3 were 1.0, 1.5, and 2.0 mg. The MTD of trametinib plus WBRT, the max dose where ≤1 of 6 patients experienced a dose limiting toxicity (DLT), was the primary endpoint.. 10 patients were enrolled (median age-59 [47-64], BM-5 [1-10], 50% melanoma). Three and 7 patients were assigned to DL1 and 2. One DL2 patient withdrew. 89% of remaining patients completed therapy per protocol, but 1 DL2 patient with systemic progression discontinued therapy at 30 Gy. Thirteen grade (G)3-4 toxicities were observed, of which 12 occurred at DL2 (4/6 of patients). DLT was reached at DL2 (G4 thrombocytopenia and G3 diarrhea, 1 each). There were no G5 toxicities. Median overall survival was 2.2 months. During the study period, changing practice patterns favored utilization of stereotactic radiosurgery (SRS). Thus, the trial closed early prior to completion.. In a patient population representative of modern candidates for WBRT, trametinib plus WBRT is highly toxic with a MTD <1.5 mg. The safety of trametinib with SRS remains an important question for future study.

Topics: Brain; Brain Neoplasms; Cranial Irradiation; Humans; Middle Aged; Prospective Studies; Pyridones; Pyrimidinones; Radiosurgery

Despite the poor prognosis associated with melanoma brain metastases (BM), data concerning these patients and their inclusion in clinical trials remains scarce. We report here the efficacy results of a subgroup analysis in patients with BRAFV600-mutant melanoma and BM treated with BRAF and MEK inhibitors dabrafenib (D) and trametinib (T).. This phase IIIb single-arm, open-label, multicenter, French study included patients with unresectable stage IIIc or IV BRAFV600-mutant melanoma with or without BM. The present analysis focuses on patients with BM. Response rates were determined clinically and/or radiologically as per standard clinical practice. Progression-free survival (PFS) was estimated using the Kaplan Meier analysis and modelled with multivariate Cox regression model. Risk subgroups were identified using an exponential regression tree analysis. Significance was set at p < 0.05.. Between March 2015 and November 2016, 856 patients were included and 275 (32%) patients had BM. Median PFS was 5.68 months (95% confidence interval [CI], 5.29-6.87). Significant independent factors associated with shorter PFS were ECOG ≥1, elevated serum lactate dehydrogenase (LDH), ≥3 metastatic sites, and non-naïve status. The binary-split classification and regression tree modelling identified baseline LDH and ECOG status as major prognostic factors.. This is to date the largest, close to real-world, study in advanced BRAFV600-mutant melanoma patients with BM treated with D+T. ECOG >1, ≥3 metastatic sites and elevated LDH were associated with shorter PFS, a finding previously demonstrated only in patients without BM. Further studies are warranted to determine the optimal treatment sequence in this population.

Topics: Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Imidazoles; Lactate Dehydrogenases; Male; Melanoma; Mitogen-Activated Protein Kinase Kinases; Mutation; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

Melanoma lacks validated blood-based biomarkers for monitoring and predicting treatment efficacy. Cell-free circulating tumour DNA (ctDNA) is a promising biomarker; however, various detection methods have been used, and, to date, no large studies have examined the association between serial changes in ctDNA and survival after BRAF, MEK, or BRAF plus MEK inhibitor therapy. We aimed to evaluate whether baseline ctDNA concentrations and kinetics could predict survival outcomes.. In this clinical validation study, we used analytically validated droplet digital PCR assays to measure BRAF. In COMBI-d, pretreatment plasma samples were available from 345 (82%) of 423 patients and on-treatment (week 4) plasma samples were available from 224 (53%) of 423 patients. In cohort A of COMBI-MB, pretreatment and on-treatment samples were available from 38 (50%) of 76 patients with intracranial and extracranial metastatic melanoma. ctDNA was detected in pretreatment samples from 320 (93%) of 345 patients (COMBI-d) and 34 (89%) of 38 patients (COMBI-MB). When assessed as a continuous variable, elevated baseline BRAF. Pretreatment and on-treatment BRAF. Novartis.

Topics: Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Circulating Tumor DNA; Double-Blind Method; Female; Follow-Up Studies; Humans; Imidazoles; Male; Melanoma; Middle Aged; Oximes; Prognosis; Pyridones; Pyrimidinones; Survival Rate

Dabrafenib plus trametinib improves clinical outcomes in BRAF. This ongoing, multicentre, multicohort, open-label, phase 2 study evaluated oral dabrafenib (150 mg twice per day) plus oral trametinib (2 mg once per day) in four patient cohorts with melanoma brain metastases enrolled from 32 hospitals and institutions in Europe, North America, and Australia: (A) BRAF. Between Feb 28, 2014, and Aug 5, 2016, 125 patients were enrolled in the study: 76 patients in cohort A; 16 patients in cohort B; 16 patients in cohort C; and 17 patients in cohort D. At the data cutoff (Nov 28, 2016) after a median follow-up of 8·5 months (IQR 5·5-14·0), 44 (58%; 95% CI 46-69) of 76 patients in cohort A achieved an intracranial response. Intracranial response by investigator assessment was also achieved in nine (56%; 95% CI 30-80) of 16 patients in cohort B, seven (44%; 20-70) of 16 patients in cohort C, and ten (59%; 33-82) of 17 patients in cohort D. The most common serious adverse events related to study treatment were pyrexia for dabrafenib (eight [6%] of 125 patients) and decreased ejection fraction (five [4%]) for trametinib. The most common grade 3 or worse adverse events, regardless of study drug relationship, were pyrexia (four [3%] of 125) and headache (three [2%]).. Dabrafenib plus trametinib was active with a manageable safety profile in this melanoma population that was consistent with previous dabrafenib plus trametinib studies in patients with BRAF. Novartis.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Female; Fever; Headache; Humans; Imidazoles; Magnetic Resonance Imaging; Male; Melanoma; Middle Aged; Mutation; Oximes; Prospective Studies; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Stroke Volume; Young Adult

A rapid, sensitive, and robust aqueous normal-phase chromatography method coupled with tandem mass spectrometry was developed and validated for the quantitation of AZD1775, a Wee-1 inhibitor, in human plasma and brain tumor tissue. Sample preparation involved simple protein precipitation with acetonitrile. Chromatographic separation was achieved on ethylene bridged hybrid stationary phases (i.e., Waters XBridge Amide column) under an isocratic elution with the mobile phase consisting of acetonitrile/ammonium formate in water (10mM, pH 3.0) (85:15,v/v) at a flow rate of 0.8mL/min for 5min. The lower limit of quantitation (LLOQ) was 0.2ng/mL of AZD1775 in plasma and tissue homogenate. The calibration curve was linear over AZD1775 concentration range of 0.2-1000ng/mL in plasma and tissue homogenate. The intra- and inter-day precision and accuracy were within the generally accepted criteria for bioanalytical method (<15%). The method was successfully applied to assess the penetration of AZD1775 across the blood-brain tumor barrier, as assessed by the unbound brain-to-plasma ratio, in patients with glioblastoma.

Topics: Brain; Brain Neoplasms; Cell Cycle Proteins; Chromatography, High Pressure Liquid; Glioblastoma; Humans; Limit of Detection; Nuclear Proteins; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Tandem Mass Spectrometry

Current therapies for recurrent or progressive high-grade gliomas (HGG, WHO grade 3-4) produce a 6-month progression-free survival of only 10-25%. Migration and invasion by HGG is mediated in part by matrix metalloproteases (MMPs) which promote remodeling of the extracellular matrix. Several HIV protease inhibitors (HIVPI) decrease the expression of MMPs in astrocytes and microglia. Given these mechanisms of antitumor activity of HIVPI, we evaluated the efficacy of ritonavir/lopinavir, a combination HIVPI, in patients with progressive or recurrent HGG in an open label phase II trial. Nineteen patients were treated in this study. Patients received ritonavir/lopinavir (400 mg/100 mg) orally twice daily. All patients were treated until progression of disease or unacceptable toxicity. A complete response was seen in one patient (5%). Three patients (16%) had stable disease as the best response. Fifteen patients (79%) had progressive disease. The 6-month progression free survival (PFS(6)) was 11% (2 of 19 patients). Ritonavir/lopinavir was well tolerated in patients with heavily pretreated refractory HGG, and no grade 3 or 4 toxicity was seen. The activity at the dose and schedule used in this study, however, was modest and the study did not meet its efficacy endpoint.

Topics: Adult; Aged; Brain Neoplasms; Disease Progression; Drug Therapy, Combination; Female; Glioma; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Neoplasm Recurrence, Local; Pyrimidinones; Ritonavir; Survival Rate; Treatment Outcome

Brain metastases (BM) and lactate dehydrogenase (LDH) levels above the upper limit of normal (ULN) are associated with poor prognosis in patients with melanoma. Although treatment with the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib have demonstrated long-term clinical benefit in patients with melanoma, data on their efficacy in patients with BM are limited.. DESCRIBE Italy is an observational, retrospective, real-world study evaluating dabrafenib plus trametinib in 499 patients with. Overall, 325 evaluable patients were on first-line therapy and are the focus of this analysis; of these, 76 patients (23.4%) had BM at baseline. mPFS was lower for patients with BM at baseline compared with overall patients (8.7 months vs 9.3 months, respectively). Patients with BM at diagnosis and LDH >ULN had a considerably shorter mPFS compared with patients with LDH ⩽ULN (5.3 months vs 9.9 months, respectively). mPFS was noticeably longer for patients with cerebral metastases only compared with patients with cerebral and other metastases (15.0 months vs 8.7 months, respectively).. Dabrafenib plus trametinib showed effectiveness in a real-world population of patients with advanced

Topics: Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Melanoma; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Retrospective Studies; Skin Neoplasms

Two reports from the phase II TADPOLE trial show the benefit of molecularly targeted therapy in pediatric brain tumors with BRAF mutations. Dabrafenib combined with trametinib was superior to chemotherapy in low-grade gliomas and yielded favorable responses in a single-arm study of high-grade ones, results that highlight the importance of biomarker testing in pediatric glioma care.

Topics: Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Child; Glioma; Humans; Mutation; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

We investigated why three patient-derived xenograft (PDX) childhood BRAFV600E-mutant brain tumor models are highly sensitive to trametinib. Mechanisms of acquired resistance selected in situ, and approaches to prevent resistance were also examined, which may translate to both low-grade glioma (LGG) molecular subtypes.. Sensitivity to trametinib [MEK inhibitor (MEKi)] alone or in combination with rapamycin (TORC1 inhibitor), was evaluated in pediatric PDX models. The effect of combined treatment of trametinib with rapamycin on development of trametinib resistance in vivo was examined. PDX tissue and tumor cells from trametinib-resistant xenografts were characterized.. In pediatric models TORC1 is activated through ERK-mediated inactivation of the tuberous sclerosis complex (TSC): consequently inhibition of MEK also suppressed TORC1 signaling. Trametinib-induced tumor regression correlated with dual inhibition of MAPK/TORC1 signaling, and decoupling TORC1 regulation from BRAF/MAPK control conferred trametinib resistance. In mice, acquired resistance to trametinib developed within three cycles of therapy in all three PDX models. Resistance to trametinib developed in situ is tumor-cell-intrinsic and the mechanism was tumor line specific. Rapamycin retarded or blocked development of resistance.. In these three pediatric BRAF-mutant brain tumors, TORC1 signaling is controlled by the MAPK cascade. Trametinib suppressed both MAPK/TORC1 pathways leading to tumor regression. While low-dose intermittent rapamycin to enhance inhibition of TORC1 only modestly enhanced the antitumor activity of trametinib, it prevented or retarded development of trametinib resistance, suggesting future therapeutic approaches using rapamycin analogs in combination with MEKis that may be therapeutically beneficial in both KIAA1549::BRAF- and BRAFV600E-driven gliomas.

Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Disease Models, Animal; Glioma; Humans; Mechanistic Target of Rapamycin Complex 1; Mice; Mitogen-Activated Protein Kinase Kinases; Mutation; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Sirolimus

Topics: Adolescent; Brain Neoplasms; Ganglioglioma; Humans; Imidazoles; Mitogen-Activated Protein Kinase Kinases; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Vemurafenib

Topics: Adolescent; Brain Neoplasms; Chemoradiotherapy; Fatal Outcome; Glioma; Humans; Imidazoles; Male; MAP Kinase Kinase Kinases; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Re-Irradiation

To describe a series of children with extensive PNF or treatment refractory PLGG treated on a compassionate basis with trametinib.. We report on six patients with NF-1 treated with trametinib on a compassionate basis at British Columbia Children's Hospital since 2017. Data were collected retrospectively from the patient record. RAPNO and volumetric criteria were used to evaluate the response of intracranial and extracranial lesions, respectively.. Subjects were 21 months to 14 years old at the time of initiation of trametinib therapy and 3/6 subjects are male. Duration of therapy was 4-28 months at the time of this report. All patients had partial response or were stable on analysis. Two patients with life-threatening PNF had a partial radiographic response in tandem with significant clinical improvement and developmental catch up. One subject discontinued therapy after 6 months due to paronychia and inadequate response. The most common adverse effect (AE) was grade 1-2 paronychia or dermatitis in 5/6 patients. There were no grade 3 or 4 AEs. At the time of this report, five patients remain on therapy.. Trametinib is an effective therapy for advanced PNF and refractory PLGG in patients with NF-1 and is well tolerated in children. Further data and clinical trials are required to assess tolerance, efficacy and durability of response, and length of treatment required in such patients.

Topics: Adolescent; Antineoplastic Agents; Brain Neoplasms; British Columbia; Child; Child, Preschool; Compassionate Use Trials; Dermatitis, Atopic; Drug Resistance, Neoplasm; Female; Glioma; Humans; Infant; Male; Neurofibroma, Plexiform; Neurofibromatosis 1; Paronychia; Pyridones; Pyrimidinones; Retrospective Studies; Treatment Outcome

The mitogen-activated protein kinase pathway is one of the most frequently altered pathways in cancer. It is involved in the control of cell proliferation, invasion, and metabolism, and can cause resistance to therapy. A number of aggressive malignancies, including melanoma, colon cancer, and glioma, are driven by a constitutively activating missense mutation (V600E) in the v-Raf murine sarcoma viral oncogene homolog B (BRAF) component of the pathway. Mitogen-activated protein kinase kinase (MEK) inhibition is initially effective in targeting these cancers, but reflexive activation of mammalian target of rapamycin (mTOR) signaling contributes to frequent therapy resistance. We have previously demonstrated that combination treatment with the MEK inhibitor trametinib and the dual mammalian target of rapamycin complex 1/2 inhibitor TAK228 improves survival and decreases vascularization in a BRAF

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzoxazoles; Brain Neoplasms; Cell Line, Tumor; Female; Glioma; Humans; Mice, Nude; Mitogen-Activated Protein Kinase Kinases; Phosphoproteins; Protein Kinase Inhibitors; Proteomics; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidines; Pyrimidinones; TOR Serine-Threonine Kinases

A patient who was initially considered to have a glioblastoma (GBM) had molecular analysis, showing that it was a pleomorphic xanthoastrocytoma (PXA). Up to 78% of PXA tumors have BRAF V600E mutations. Primary brain tumors with BRAF mutations can have a good response to BRAF MEK inhibitors (BRAF MEKi), and there may be a synergistic response when combined with autophagy inhibitors.. A 20-year-old man found to have a large brain mass with midline shift underwent resection. He was diagnosed with "GBM" and treated with radiation and temozolomide with subsequent disease recurrence. Review of histology showed malignant PXA with BRAF V600E mutation. Treatment with Dabrafenib and Trametinib was started, and tumor size increased in size after 14 months of treatment. Given studies showing that resistance to BRAF inhibition can be overcome by autophagy inhibition, chloroquine was added. Patient has been on "triple" therapy for 15 months and has radiographically Stable Disease. At MCC, 3% of patients with gliomas have BRAF mutations who could potentially benefit from this combination therapy.. This is the first report of a PXA patient receiving therapy with BRAF MEKi and an autophagy inhibitor with prolonged stable disease. This patient highlights the importance of a molecular interrogation in gliomas to provide an integrated diagnosis and effective treatment. This may be useful in up to 3% of glioma patients with BRAF mutations. Molecular testing in neuro-oncology is providing new avenues of diagnosis and treatment, and detailed molecular interrogation should be considered routine.

Topics: Antineoplastic Combined Chemotherapy Protocols; Astrocytoma; Brain Neoplasms; Chloroquine; Drug Resistance, Neoplasm; Humans; Imidazoles; Male; Oximes; Precision Medicine; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Young Adult

Topics: Adult; Antibodies, Monoclonal, Humanized; Antigens, CD20; Antineoplastic Agents, Immunological; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Chemotherapy, Adjuvant; Glucocorticoids; Humans; Imidazoles; Interferon-beta; Male; Melanoma; Multiple Sclerosis; Neoplasm Recurrence, Local; Oximes; Polyethylene Glycols; Pyridones; Pyrimidinones; Skin Neoplasms; Treatment Outcome

Glioblastoma (GB) is a highly aggressive, difficult to treat brain tumour. Successful treatment, consisting of maximal safe tumour de-bulking, followed by radiotherapy and treatment with the alkylating agent Temozolomide (TMZ), can extend patient survival to approximately 15 months. Combination treatments based on the inhibition of the PI3K pathway, which is the most frequently activated signalling cascade in GB, have so far only shown limited therapeutic success. Here, we use the clinically approved MEK inhibitor Trametinib to investigate its potential use in managing GB. Trametinib has a strong anti-proliferative effect on established GB cell lines, stem cell-like cells and their differentiated progeny and while it does not enhance anti-proliferative and cell death-inducing properties of the standard treatment, i.e. exposure to radiation or TMZ, neither does MEK inhibition block their effectiveness. However, upon MEK inhibition some cell populations appear to favour cell-substrate interactions in a sprouting assay and become more invasive in the Chorioallantoic Membrane assay, which assesses cell penetration into an organic membrane. While this increased invasion can be modulated by additional inhibition of the PI3K signalling cascade, there is no apparent benefit of blocking MEK compared to targeting PI3K.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Brain Neoplasms; Cell Adhesion; Cell Death; Cell Line, Tumor; Cell Proliferation; Chorioallantoic Membrane; Drug Screening Assays, Antitumor; Glioblastoma; Humans; MAP Kinase Kinase 1; Neoplasm Invasiveness; Neoplasm Metastasis; Phosphatidylinositol 3-Kinases; Phosphorylation; Pyridones; Pyrimidinones; Signal Transduction; Temozolomide; Translational Research, Biomedical

Topics: Adenocarcinoma of Lung; Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Combined Modality Therapy; Humans; Imidazoles; Lung Neoplasms; MAP Kinase Kinase 1; Mutation; Oximes; Prognosis; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Radiosurgery

Pediatric low-grade gliomas (pLGGs) are the most common CNS tumor of childhood and comprise a heterogenous group of tumors. Children with progressive pLGG often require numerous treatment modalities including surgery, chemotherapy, rarely radiation therapy and, more recently, molecularly targeted therapy. We describe our institutional experience using the MEK inhibitor, trametinib, for recurrent/progressive pLGGs.. We performed a retrospective, IRB-approved, chart review of all pediatric patients treated with trametinib for recurrent/progressive pLGGs at Dana-Farber/Boston Children's Cancer and Blood Disorder Center between 2016 and 2018.. Eleven patients were identified, of which 10 were evaluable for response. Median age at commencement of trametinib treatment was 14.7 years (range 7.3-25.9 years). Tumor molecular status included KIAA1549-BRAF fusion (n = 4), NF1 mutation (n = 4), FGFR mutation (n = 1) and CDKN2A loss (n = 1). Median number of prior treatment regimens was 5 (range 1-12). Median duration of treatment with trametinib was 19.2 months (range 3.8-29.8 months). Based on modified RANO criteria, best responses included partial (n = 2), minor response (n = 2) and stable disease (n = 6). Two patients remain on therapy (29.8 and 25.9 months, respectively). The most common toxicities attributable to trametinib were rash, fatigue and gastrointestinal disturbance. Five patients required dose reduction for toxicities. Two patients experienced significant intracranial hemorrhage (ICH) while on trametinib. While it is unclear whether ICH was directly attributable to trametinib, therapy was discontinued.. Trametinib appears to be an effective treatment for patients with recurrent/progressive pLGG. The toxicities of this therapy warrant further investigation, with particular attention to the potential risk for intracranial hemorrhage. Early phase multi-institutional clinical trials are underway.

Topics: Adolescent; Adult; Antineoplastic Agents; Brain Neoplasms; Child; Female; Follow-Up Studies; Glioma; Humans; Male; Neoplasm Recurrence, Local; Prognosis; Pyridones; Pyrimidinones; Retrospective Studies; Young Adult

Clinical trials of MEK inhibitors are underway in pediatric low-grade glioma (PLGG) with BRAF oncogene mutations and recurrent/refractory disease. Cognitive and behavioral impacts of MEK inhibitors, such as trametinib, are unknown as these outcomes have not yet been studied. This case series compared cognition and behavior in eight PLGG cases prior to and while on treatment with trametinib compared to four PLGG controls. Intelligence in the trametinib cases was mainly unchanged while on treatment, with mild decline in one of seven cases with complete data. Parent-reported depression symptoms increased in five of eight trametinib cases relative to one of four controls.

Topics: Antineoplastic Agents; Brain Neoplasms; Child; Child, Preschool; Cognitive Dysfunction; Depression; Drug-Related Side Effects and Adverse Reactions; Female; Follow-Up Studies; Glioma; Humans; Infant; Male; Neuropsychological Tests; Prognosis; Pyridones; Pyrimidinones

Aquaporin 1 (AQP1), a transmembrane protein that forms water channels, has previously been shown to facilitate growth and progression of many types of tumors by modulating tumor cell migration, proliferation and angiogenesis. Here, we determined the impact of AQP1 expression in the tumor environment on the progression of brain tumors. Primary microglia from wild type(WT) and AQP1 knockout(KO) mice were used to test AQP1 effect on microglia function by using Western blot, quantative PCR, in an experimental in vivo mouse glioma model and organotypic brain slice culture. Deletion of AQP1 in the host tissue significantly reduced the survival of the mice implanted with GL261 glioma cells. The density of glioma-associated microglia/macrophages was almost doubled in AQP1KO mice. We found that factors secreted from GL261 cells decrease microglial AQP1 expression via the MEK/ERK pathway, and that inhibition of this pathway with Trametinib reduced tumor growth and prolonged the survival of tumor bearing mice, an effect which required the presence of microglia. Deletion of AQP1 in cultured microglia resulted in an increase in migratory activity and a decrease in TLR4-dependent innate immune responses. Our study demonstrates a functional relevance of AQP1 expression in microglia and hints to AQP1 as a potential novel target for glioma therapy.

Topics: Animals; Aquaporin 1; Astrocytes; Biomarkers, Tumor; Brain Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Disease Progression; Down-Regulation; Gene Deletion; Gene Expression Regulation, Neoplastic; Glioma; Inflammation; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Phenotype; Pyridones; Pyrimidinones; RAW 264.7 Cells

There is a wide variety of pancreatic neoplasms identified, but the great majority of them are of primary origin. Metastatic disease in the pancreatic parenchyma is quite rare (2-5% of pancreatic malignancies) and most often is quite difficult to differentiate from other primary lesions. Most of the imaging studies fail to give certain discriminating features for metastatic pancreatic neoplasms, contrary to endoscopic ultrasound and tissue sampling, which can provide an accurate diagnosis. In this report, we present a case of a male middle aged man who was admitted to our hospital with painless jaundice and finally was diagnosed with a cutaneous scalp melanoma dispersedly metastasized to the pancreas and upper gastrointestinal tract (stomach and duodenum).

Topics: Adrenal Gland Neoplasms; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Cholangiopancreatography, Endoscopic Retrograde; Cranial Irradiation; Duodenal Neoplasms; Endoscopic Ultrasound-Guided Fine Needle Aspiration; Endoscopy, Digestive System; Endosonography; Humans; Imidazoles; Lung Neoplasms; Male; Melanoma; Middle Aged; Oximes; Pancreatic Neoplasms; Pyridones; Pyrimidinones; Skin Neoplasms; Stomach Neoplasms; Tomography, X-Ray Computed

Malignant melanoma is the most aggressive type of skin cancer and is closely associated with the development of brain metastases. Despite aggressive treatment, the prognosis has traditionally been poor, necessitating improved therapies. In melanoma, the mitogen activated protein kinase and the phosphoinositide 3-kinase signaling pathways are commonly altered, and therapeutically inhibiting one of the pathways often upregulates the other, leading to resistance. Thus, combined treatment targeting both pathways is a promising strategy to overcome this. Here, we studied the in vitro and in vivo effects of the PI3K inhibitor buparlisib and the MEK1/2 inhibitor trametinib, used either as targeted monotherapies or in combination, on patient-derived melanoma brain metastasis cell lines. Scratch wound and trans-well assays were carried out to assess the migratory capacity of the cells upon drug treatment, whereas flow cytometry, apoptosis array and Western blots were used to study apoptosis. Finally, an in vivo treatment experiment was carried out on NOD/SCID mice. We show that combined therapy was more effective than monotherapy. Combined treatment also more effectively increased apoptosis, and inhibited tumor growth in vivo. This suggests a clinical potential of combined treatment to overcome ceased treatment activity which is often seen after monotherapies, and strongly encourages the evaluation of the treatment strategy on melanoma patients with brain metastases.

Topics: Aminopyridines; Animals; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Cell Line, Tumor; Melanoma; Mice, Inbred NOD; Mice, SCID; Mitogen-Activated Protein Kinases; Morpholines; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; Signal Transduction; Skin Neoplasms; Treatment Outcome; Tumor Burden; Xenograft Model Antitumor Assays

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Astrocytoma; Bevacizumab; Brain Neoplasms; Female; Humans; Imidazoles; Meningeal Carcinomatosis; Mutation; Oximes; Prognosis; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

BRAF and MEK kinase inhibitors can be highly effective in treating BRAF-mutant melanomas, but their safety and activity in patients with active/symptomatic brain metastases are unclear. We sought to shed light on this open clinical question. We conducted a multicenter retrospective study on real-life patients with melanoma and active brain metastases treated with combination BRAF/MEK inhibitors. A total of 65 patients were included (38 men and 27 women; median age: 49 years). Of them, 53 patients received dabrafenib/trametinib, 10 received vemurafenib/cobimetinib, one received encorafenib/binimetinib, and one received vemurafenib/trametinib. We did not observe any unexpected treatment-related safety signals in our cohort. Overall, 17 patients continued on therapy through the cutoff date. After initiation of therapy, steroid dose could be decreased in 22 of 33 patients (11 tapered off entirely), anticonvulsants were stopped in four of 21, and narcotics were stopped in four of 12. Median progression-free survival from the start of therapy was 5.3 months (95% confidence interval: 3.6-6.1), and median overall survival was 9.5 months (95% confidence interval: 7.7-13.5). A total of 20 patients were surviving at the cutoff date. Univariate analysis of age, sex, ulceration status, thickness, stage, location, or lactate dehydrogenase did not reveal significant predictors of progression-free survival or overall survival within our cohort, but multivariate analysis suggested that older age, lower risk location of original lesion, and nodular melanoma are poor prognostic indicators. Combination therapy with BRAF/MEK inhibitors is a viable treatment option for patients with BRAF-mutant melanoma and brain metastases, but further studies should help to define the optimal treatment approach in this population.

Topics: Adolescent; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Biomarkers, Tumor; Brain Neoplasms; Female; Follow-Up Studies; Humans; Imidazoles; Male; MAP Kinase Kinase 1; Melanoma; Middle Aged; Oximes; Prognosis; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Retrospective Studies; Survival Rate; Young Adult

Glioblastoma is the most common type of primary brain tumour in adults, and its pathogenesis is particularly complicated. Among the many possible mechanisms underlying its pathogenesis, hyperactivation of the PI3K/Akt pathway is essential to the occurrence and development of glioma through the loss of PTEN or somatic activating mutations in PIK3CA. In the present study, we investigated the effect of the PI3Kβ inhibitor AZD6482 on glioma cells. The CCK-8 assay showed dose-dependent cytotoxicity in glioma cell lines treated with AZD6482. Additionally, AZD6482 treatment was found to significantly induce apoptosis and cell cycle arrest as detected using flow cytometry. Moreover, as shown using western blot analysis, the levels of p-AKT, p-GSK-3β, Bcl-2, and cyclin D1 were decreased after AZD6482 treatment. In addition, we found that AZD6482 inhibited the migration and invasion of glioma cells as detected by wound healing and Transwell invasion assays. Taken together, our findings indicate that AZD6482 exerts an antitumour effect by inhibiting proliferation and inducing apoptosis in human glioma cells. AZD6482 may be applied as an adjuvant therapy to improve the therapeutic efficacy of glioblastoma treatment.

Topics: Apoptosis; Brain Neoplasms; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Movement; Cell Proliferation; Class I Phosphatidylinositol 3-Kinases; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Glioblastoma; Humans; Mutation; ortho-Aminobenzoates; Protein Kinase Inhibitors; PTEN Phosphohydrolase; Pyrimidinones; Signal Transduction

Elevated endogenous phosphoinositide-3-kinase (PI3K) activity is critical for cell proliferation in gliomas. Iron availability is one of the essential factors for cell growth and proliferation. However, any relation between PI3K and cellular iron homeostasis has not been understood so far.. Glioma cells and human primary astrocytes were treated with class I PI3K inhibitors to examine regulation of iron homeostasis components. Regulation of ferritin was detected at mRNA and translational level. Labile iron pool (LIP) and cell proliferation were examined in glioma cells and human primary astrocytes.. Blocking of PI3K activity elevated ferritin level by 6-10 folds in glioma cells by augmenting mRNA expression of ferritin subunits and also by influencing ferritin translation. IRE-IRP interaction was affected due to conversion of IRP1 to cytosolic aconitase that was influenced by increased iron-sulfur scaffold protein iron-sulfur cluster assembly enzyme (ISCU) level. Elevated ferritin sequestered LIP to affect cell proliferation that was reversed in silencing ferritin by siRNAs of ferritin-H and ISCU. Human primary astrocyte with little PI3K activity did not show any change in ferritin level, LIP and cell proliferation by PI3K inhibitors.. PI3K inhibition promotes ferritin synthesis by dual mechanism resulting sequestration of iron to limit its availability for cell proliferation in glioma cells but not in primary astrocytes.. This observation establishes a relation between PI3K signalling and iron homeostasis in glioma cells. It also implies that activated PI3K controls ferritin expression to ensure availability of adequate iron required for cell proliferation.

Topics: Adenine; Animals; Brain Neoplasms; Cell Proliferation; Cells, Cultured; Chromones; Down-Regulation; Ferritins; Glioma; Humans; Iron; Morpholines; Phosphoinositide-3 Kinase Inhibitors; Pyrimidinones; Quinazolines; Rats; Thiazolidinediones; Up-Regulation

Topics: Adenocarcinoma of Lung; Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Imidazoles; Lung Neoplasms; Male; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

Hyperactivation of the RAS-RAF-MEK-ERK signaling pathway is exploited by glioma cells to promote their growth and evade apoptosis. MEK activation in tumor cells can increase replication of ICP34.5-deleted herpes simplex virus type 1 (HSV-1), but paradoxically its activation in tumor-associated macrophages promotes a pro-inflammatory signaling that can inhibit virus replication and propagation. Here we investigated the effect of blocking MEK signaling in conjunction with oncolytic HSV-1 (oHSV) for brain tumors.. Infected glioma cells co-cultured with microglia or macrophages treated with or without trametinib were used to test trametinib effect on macrophages/microglia. Enzyme-linked immunosorbent assay, western blotting, and flow cytometry were utilized to evaluate the effect of the combination therapy. Pharmacokinetic (PK) analysis of mouse plasma and brain tissue was used to evaluate trametinib delivery to the CNS. Intracranial human and mouse glioma-bearing immune deficient and immune competent mice were used to evaluate the antitumor efficacy.. Oncolytic HSV treatment rescued trametinib-mediated feedback reactivation of the mitogen-activated protein kinase signaling pathway in glioma. In vivo, PK analysis revealed enhanced blood-brain barrier penetration of trametinib after oHSV treatment. Treatment by trametinib, a MEK kinase inhibitor, led to a significant reduction in microglia- and macrophage-derived tumor necrosis factor alpha (TNFα) secretion in response to oHSV treatment and increased survival of glioma-bearing mice. Despite the reduced TNFα production observed in vivo, the combination treatment activated CD8+ T-cell mediated immunity and increased survival in a glioma-bearing immune-competent mouse model.. This study provides a rationale for combining oHSV with trametinib for the treatment of brain tumors.

Topics: Animals; Blood-Brain Barrier; Brain Neoplasms; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Disease Models, Animal; Glioblastoma; Glioma; Herpesvirus 1, Human; Humans; Immunocompetence; Macrophages; Mice; Microglia; Mitogen-Activated Protein Kinase Kinases; Oncolytic Virotherapy; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; RAW 264.7 Cells; Survival Rate; Tumor Necrosis Factor-alpha; Xenograft Model Antitumor Assays

Topics: Brain Neoplasms; Glioma; Humans; Oncolytic Virotherapy; Pyridones; Pyrimidinones

Pleomorphic xanthoastrocytoma is a rare brain tumor with unique high frequency of BRAF V600E mutation which is plausible for targeted therapy. The anaplastic variant has generally worse prognosis. We present an adolescent patient with a disseminated relapse of anaplastic pleomorphic xanthoastrocytoma following surgery, radiotherapy, and chemotherapy. She had a dramatic and prolonged response to a BRAF inhibitor (Dabrafinib) and later to addition of a MEK inhibitor (Trametinib) on tumor progression. With minimal side effects and a good quality of life, the patient is alive more than 2 years after initiation of targeted therapy. This experience confirms the potential role of targeted treatments in high-grade BRAF-mutated brain tumors.

Topics: Adolescent; Amino Acid Substitution; Astrocytoma; Brain Neoplasms; Female; Humans; Imidazoles; Mutation, Missense; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

Patients with brain metastases (BM) from melanoma have an overall survival (OS) of 2-6 months after whole-brain radiotherapy. Targeted therapy (TT) is an effective treatment for BRAF-mutated metastatic melanoma. Moreover, recent studies indicate intracranial responses of TT in patients with BM. We analyzed 146 patients with BM from BRAF-mutated melanoma treated with vemurafenib, dabrafenib, or dabrafenib+trametinib between 2010 and 2016. We determined clinical and radiological response, progression-free survival (PFS), and OS. Median OS of patients treated with dabrafenib+trametinib was 11.2 months [n=30; 95% confidence interval (CI): 6.8-15.7], 8.8 months for dabrafenib alone (n=31; 95% CI: 3.9-13.7), and 5.7 months for vemurafenib (n=85; 95% CI: 4.6-6.8). A significantly longer OS was observed in the dabrafenib+trametinib group than in the vemurafenib group (hazard ratio for death, 0.52; 95% CI: 0.30-0.89; P=0.02). Median intracranial PFS of all patients was 4.1 months. Median intracranial PFS for patients treated with dabrafenib+trametinib was 5.8 months (95% CI: 3.2-8.5), 5.7 months (95% CI: 3.0-8.4) for dabrafenib, and 3.6 months (95% CI: 3.5-3.8) for vemurafenib (P=0.54). A total of 63 (43%) patients had symptomatic BM. Intracranial disease control rate at 8 weeks in these patients was 65 versus 70% extracranially. Neurological symptoms improved in 46% of patients with symptomatic BM, whereas in 21%, they remained stable. Median OS in patients with BM from BRAF-mutated melanoma treated with dabrafenib+trametinib was significantly longer than for vemurafenib. Improvement of neurological symptoms was seen in almost half of the patients with symptomatic BM treated with TT.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Imidazoles; Male; MAP Kinase Kinase Kinases; Melanoma; Middle Aged; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Retrospective Studies; Skin Neoplasms; Treatment Outcome; Vemurafenib; Young Adult

Efficacy of BRAF V600E targeted therapies in brain tumors harboring the mutation has been shown in several case reports and is currently being studied in larger clinical trials. Monotherapy with vemurafenib has been associated with significant side effects, including rashes, papillomas, and squamous cell carcinomas. Here we describe an adolescent female with anaplastic ganglioglioma and significant skin reaction to vemurafenib with subsequent tumor response and tolerance to the BRAF/MEK inhibitor combination of dabrafenib and trametinib without recurrence of previous reaction.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Drug Resistance, Neoplasm; Female; Ganglioglioma; Humans; Imidazoles; MAP Kinase Kinase 1; Mutation; Oximes; Prognosis; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Vemurafenib

The strategy of using biologically targeted therapeutics for cancer has yet to translate into effective treatment of gliomas. The neuro-oncology community is beginning to recognize that phase 0 studies should be performed to account for the impact of the blood-brain barrier on the ability of a therapeutic to reach its target(s).

Topics: Brain Neoplasms; Glioblastoma; Humans; Pyrazoles; Pyrimidines; Pyrimidinones

A series of hybrid aza heterocycles containing pyrazolo[3,4-d]pyrimidin-4(5H)-ones tethered to 1,2,3-triazole scaffold were synthesized from 1,3-dipolar cycloaddition reaction of pyrazolopyrimidinone based alkyne with azides using Cu(II) catalyst in presence of sodium ascorbate and evaluated for their anticancer efficacy in vitro against C6 rat and U87 human glioma cell lines. These compounds induced a concentration dependent inhibition of C6 rat and U87 human glioma cell proliferation. Compound 5f arrested the cells at S-phase of the cell cycle and induced apoptosis in U87 GBM cell lines. Further, apoptosis was evidenced by the cleavage of Caspase-3, PARP and up regulation of p53. In silico docking studies reveal that the compounds 5a, 5f and 5l were more effective in binding with TGFBR2 than other compounds.

Topics: Animals; Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Chemistry Techniques, Synthetic; Drug Screening Assays, Antitumor; Glioma; Humans; Molecular Docking Simulation; Protein Serine-Threonine Kinases; Pyrazoles; Pyrimidinones; Rats; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Triazoles

Pediatric pilocytic astrocytomas (PAs) are low grade gliomas and the most common brain tumors in children. They often represent a therapeutic challenge when incompletely resected as they can recur and progress despite the use of several lines of chemotherapeutic agents or even radiation therapy. Genetic alterations leading to activation of the mitogen-activated-protein-kinase pathway are a hallmark of this disease and offer an interesting therapeutic alternative through the use of targeted inhibitors.. Here, we describe six children with sporadic PA who were treated with trametinib, a MEK inhibitor, following progression under conventional therapies. Retrospective chart review was performed.. The median age at diagnosis was 2.3 years (y) old [range 11 months (m)-8.5 y old]. KIAA1549-BRAF fusion was identified in five cases, and hotspot FGFR1/NF1/PTPN11 mutations in one. All patients received at least one previous line of chemotherapy (range 1-4). The median time on treatment was 11 m (range 4-20). Overall, we observed two partial responses and three minor responses as best response; three of these patients are still on therapy. Treatment was discontinued in the patient with progressive disease. The most frequent toxicities were minor to moderately severe skin rash and gastro-intestinal symptoms. Two patients had dose reduction due to skin toxicity. Quality of life was excellent with decreased hospital visits and a close to normal life.. Trametinib appears to be a suitable option for refractory pediatric low-grade glioma and warrants further investigations in case of progression.

Topics: Antineoplastic Agents; Astrocytoma; Brain Neoplasms; Child; Child, Preschool; Disease Progression; Female; Humans; Infant; Male; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; Retreatment; Retrospective Studies

It is generally known that glioblastoma is the most common primary malignant brain tumor and that it is highly aggressive and deadly. Although surgical and pharmacological therapies have made long‑term progress, glioblastoma remains extremely lethal and has an uncommonly low survival rate. Therefore, further elucidation of the molecular mechanisms of glioblastoma initiation and its pathological processes are urgent. Arsenic resistance protein 2 (Ars2) is a highly conserved gene, and it has been found to play an important role in microRNA biosynthesis and cell proliferation in recent years. Furthermore, absence of Ars2 results in developmental death in Drosophila, zebrafish and mice. However, there are few studies on the role of Ars2 in regulating tumor development, and the mechanism of its action is mostly unknown. In the present study, we revealed that Ars2 is involved in glioblastoma proliferation and we identified a potential mechanistic role for it in cell cycle control. Our data demonstrated that Ars2 knockdown significantly repressed the proliferation and tumorigenesis abilities of glioblastoma cells in vitro and in vivo. Further investigation clarified that Ars2 deficiency inhibited the activation of the MAPK/ERK pathway, leading to cell cycle arrest in the G1 phase, resulting in suppression of cell proliferation. These findings support the conclusion that Ars2 is a key regulator of glioblastoma progression.

Topics: Animals; Brain Neoplasms; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Disease Progression; Female; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Glioblastoma; Humans; MAP Kinase Signaling System; Mice; Mice, Inbred NOD; Mice, SCID; Nuclear Proteins; Phosphorylation; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; Xenograft Model Antitumor Assays

BRAFV600E mutations have been identified in a number of glioma subtypes, most frequently in pleomorphic xanthoastrocytoma, ganglioglioma, pilocytic astrocytoma, and epithelioid glioblastoma. Although the development of BRAF inhibitors has dramatically improved the clinical outcome for patients with BRAFV600E mutant tumors, resistance develops in a majority of patients due to reactivation of the MAPK pathway. Addition of MEK inhibition to BRAF inhibition improves survival. Here we report successful treatment of two patients with BRAFV600E mutant pleomorphic xanthoastrocytoma using the BRAF inhibitor dabrafenib in combination with the MEK inhibitor trametinib.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Female; Glioma; Humans; Imidazoles; Middle Aged; Mutation; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

Glioblastoma is the most common type of primary brain tumor in adults, with high mortality and morbidity rates. More effective therapeutic strategies are imperative. Previous studies have shown that the known p110-β-selective inhibitor TGX-221 blocks the activation of PKB/Akt in PTEN-deficient cells. We treated U87 and U251 glioblastoma cells with TGX-221 to determine the effect of TGX-221. We performed a Cell Counting Kit-8 (CCK-8) test, EDU staining and cell cycle distribution analysis and found that TGX-221 inhibited glioblastoma cell proliferation. Next, the effect of TGX-221 on cell apoptosis was investigated using flow cytometry. These results demonstrated that TGX-221 induced apoptosis in glioblastoma cells. Moreover, migration and invasion assays revealed that TGX-221 inhibited human glioblastoma cell migration and invasion. Collectively, our study revealed that TGX-221 could inhibit proliferation and induce apoptosis in glioblastoma cells.

Topics: Brain Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Class I Phosphatidylinositol 3-Kinases; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Morpholines; Proto-Oncogene Proteins c-akt; Pyrimidinones; Signal Transduction

Topics: Aged; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Imidazoles; Male; Melanoma; Oximes; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Remission Induction; Skin Neoplasms

A phase I/II clinical trial suggests that dabrafenib shrinks or stabilizes low-grade gliomas in children with the BRAF V600E mutation. Objective, durable responses occurred in 38% of patients, and the side effects were less severe than with chemotherapy. The researchers have started a second trial for patients with glioma and other BRAF-mutant tumor types, this time evaluating dabrafenib combined with trametinib.

Topics: Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Child; Clinical Trials as Topic; Disease-Free Survival; Female; Glioma; Humans; Imidazoles; Male; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Survival Analysis; Treatment Outcome

The combined use of the BRAF inhibitor dabrafenib and MEK inhibitor trametinib has been found to improve survival over dabrafenib alone. The management of melanoma brain metastases continues to present challenges. In this study, we report our initial experience in the management of melanoma brain metastases with stereotactic radiosurgery (SRS) with the use of BRAF and MEK inhibitors. We identified six patients treated with SRS for 17 brain metastases within 3 months of BRAF and MEK inhibitor administration. The median planning target volume was 0.42 cm (range: 0.078-2.08 cm). The median treatment dose was 21 Gy (range 18-24 Gy). The median follow-up of all lesions from SRS was 10.6 months (range 5.8-28.5 months). One lesion was found to undergo local failure 21.7 months following SRS treatment. The median overall survival was 20.0 months (range 6.1-31.8 months) from the time of SRS treatment and 23.1 months (range: 12.1-30.9 months) from the date of BRAFi and MEKi administration. There was no evidence of increased nor unexpected toxicity with the two modalities combined. In this initial experience of melanoma brain metastases treated with BRAF and MEK inhibition with SRS, we find the two modalities can be combined safely. These outcomes should be assessed further in prospective evaluations.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Chemoradiotherapy; Female; Humans; Imidazoles; Male; MAP Kinase Kinase 1; Melanoma; Middle Aged; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Radiosurgery; Skin Neoplasms

Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332-43. ©2016 AACR.

Topics: Animals; Biomarkers, Tumor; Brain Neoplasms; CDC2 Protein Kinase; Cell Cycle Proteins; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Mass Spectrometry; Mice; Molecular Targeted Therapy; Nuclear Proteins; Phosphorylation; Protein-Tyrosine Kinases; Proteomics; Pyrazoles; Pyrimidines; Pyrimidinones; Xenograft Model Antitumor Assays

Novel systemic therapies with anti-tumor activity in the brain including small molecules targeting BRAF and MEK, and immune checkpoint inhibition, offer the possibility of improved control of intracranial disease. A number of prospective trials support the judicious use of modern systemic therapies in patients with melanoma and limited brain metastases .The intracranial clinical course of patients who progress extracranially on BRAF/MEK inhibition remains poorly described in the literature. In this report, we highlight a series of clinical cases, with rapid progression of intracranial disease following discontinuation of dabrafenib/trametinib for extracranial disease progression or toxicity, a previously unreported finding in the medical literature with significant implications for patient care.

Topics: Adult; Brain Neoplasms; Humans; Imidazoles; Magnetic Resonance Imaging; Male; MAP Kinase Kinase Kinases; Melanoma; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

Combination therapy with dabrafenib and trametinib is safer and more effective than BRAF inhibitor-based monotherapy for metastatic melanoma.. We retrospectively analyzed BRAF-mutated metastatic melanoma patients treated at our institution with daily oral dabrafenib 300 mg and trametinib 2 mg from November 2013 to April 2016. This clinical record included both untreated and previously treated stage IV melanomas. Physical examination and laboratory examinations were performed monthly and disease re-evaluations were performed every 3 months.. A total of 48 patients (24 male, 24 female) with BRAF-mutated metastatic melanoma received dabrafenib and trametinib; median age was 48 years (range 23-75). Median follow-up was 362.5 days (range 72-879). Best overall response rate consisted of 6.2% (3 patients) complete response, 64.6% (31) partial response, and 25% (12) stable disease; median time to best response was 11 weeks (range 5.7-125.5). Progression of disease was seen in 19 patients (39.6%), with median time to progression (TTP) of 26 weeks (range 8-54). A total of 15 patients (31.2%) died due to progression of disease. Median progression-free survival and median overall survival were not reached. To date, 30 patients (62.5%) are still under treatment. A total of 27 (56.2%) patients had at least one adverse event (AE); grade 3-4 AEs were seen in 4 cases (8.3%). The main toxicities were fever (25%), skin rash (14.6%), arthralgias (10.4%), and aspartate aminotransferase/alanine aminotransferase increase (8.3%). Treatment dose was reduced in 7 subjects (14.6%), with only one case of discontinuation due to AE.. Our data, using combined targeted therapy, are in line with the scientific literature in terms of both safety and effectiveness in a real-life setting.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Female; Follow-Up Studies; Humans; Imidazoles; Male; Melanoma; Middle Aged; Molecular Targeted Therapy; Mutation; Neoplasm Metastasis; Neoplasm Staging; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Retrospective Studies; Treatment Outcome; Young Adult

Biosensor imaging of redundant deviation in shifts (BIRDS), an ultrafast chemical shift imaging technique, requires infusion of paramagnetic probes such as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis methylene phosphonate (DOTP(8-) ) complexed with thulium (Tm(3+) ) ion (i.e. TmDOTP(5-) ), where the pH-sensitive resonances of hyperfine-shifted non-exchangeable protons contained within the paramagnetic probe are detected. While imaging extracellular pH (pHe ) with BIRDS meets an important cancer research need by mapping the intratumoral-peritumoral pHe gradient, the surgical intervention used to raise the probe's plasma concentration limits longitudinal scans on the same subject. Here we describe using probenecid (i.e. an organic anion transporter inhibitor) to temporarily restrict renal clearance of TmDOTP(5-) , thereby facilitating molecular imaging by BIRDS without surgical intervention. Co-infusion of probenecid with TmDOTP(5-) increased the probe's distribution into various organs, including the brain, compared with infusing TmDOTP(5-) alone. In vivo BIRDS data using the probenecid-TmDOTP(5-) co-infusion method in rats bearing RG2, 9 L, and U87 brain tumors showed intratumoral-peritumoral pHe gradients that were unaffected by the probe dose. This co-infusion method can be used for pHe mapping with BIRDS in preclinical models for tumor characterization and therapeutic monitoring, given the possibility of repeated scans with BIRDS (e.g. over days and even weeks) in the same subject. The longitudinal pHe readout by the probenecid-TmDOTP(5-) co-infusion method for BIRDS adds translational value in tumor assessment and treatment. Copyright © 2016 John Wiley & Sons, Ltd.

Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Glioma; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Male; Molecular Probe Techniques; Molecular Probes; Oxazoles; Pyrimidinones; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Reproducibility of Results; Sensitivity and Specificity

Here, we studied the anti-glioma cell activity by a novel AMP-activated protein kinase (AMPK) activator GSK621. We showed that GSK621 was cytotoxic to human glioma cells (U87MG and U251MG lines), possibly via provoking caspase-dependent apoptotic cell death. Its cytotoxicity was alleviated by caspase inhibitors. GSK621 activated AMPK to inhibit mammalian target of rapamycin (mTOR) and downregulate Tetraspanin 8 (Tspan8) in glioma cells. AMPK inhibition, through shRNA knockdown of AMPKα or introduction of a dominant negative (T172A) AMPKα, almost reversed GSK621-induced AMPK activation, mTOR inhibition and Tspan8 degradation. Consequently, GSK621's cytotoxicity in glioma cells was also significantly attenuated by AMPKα knockdown or mutation. Further studies showed that GSK621, at a relatively low concentration, significantly potentiated temozolomide (TMZ)'s sensitivity and lethality against glioma cells. We summarized that GSK621 inhibits human glioma cells possibly via activating AMPK signaling. This novel AMPK activator could be a novel and promising anti-glioma cell agent.

Topics: AMP-Activated Protein Kinases; Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cell Survival; Dacarbazine; Down-Regulation; Drug Resistance, Neoplasm; Enzyme Activation; Gene Knockdown Techniques; Glioma; Humans; Imidazoles; Pyrimidinones; Signal Transduction; Temozolomide; Tetraspanins; TOR Serine-Threonine Kinases

The standard management of a single brain metastasis is usually maximal resection when feasible followed by radiotherapy. In case of multiple lesions, several options have to be considered depending on the natural behavior of the primary tumor, the localization of brain lesions, their functional impact and related symptoms. In case of life-threatening brain metastasis, debulking surgery is often proposed first, with the risk of major bleeding and postponing the initiation of other treatments. This approach is now challenged by the rapid tumor shrinkage that could be observed with novel targeted therapies. Here we report the case of a patient suffering from a melanoma with multiple brain metastasis, treated with BRAF and MEK double blockade, with impressive and rapid response.

Topics: Brain; Brain Neoplasms; Humans; Imidazoles; Lymph Node Excision; Lymph Nodes; Magnetic Resonance Imaging; Melanoma; Middle Aged; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones

The management of metastatic melanoma has changed significantly in the past decade with the development of immunotherapies and targeted molecular therapies. Trials of targeted therapies have focused mainly on patients with the most common BRAF V600 mutations, namely V600E/K substitutions, with very little information available on the benefit of targeted therapies on less commonly occurring mutations such as V600R/D and M.. We present a 54-year-old man with metastatic melanoma harbouring a rare BRAF V600M mutation, who experienced clinical and radiological response to combined therapy with the BRAF inhibitor dabrafenib and MEK inhibitor trametinib.. As our understanding of these therapies evolves and an increasing number of patients have mutational testing performed, there is a clear imperative--as highlighted by this case--to test for rarer mutations and facilitate their inclusion both in everyday practice and in future clinical trials.

Topics: Abdominal Neoplasms; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Humans; Imidazoles; Intestinal Neoplasms; Lymphatic Metastasis; Male; Melanoma; Middle Aged; Molecular Targeted Therapy; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Skin Neoplasms; Treatment Outcome

Topics: Aged; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Brain Neoplasms; Carrier Proteins; Disease Progression; DNA Mutational Analysis; Female; Humans; Intracellular Signaling Peptides and Proteins; Magnetic Resonance Imaging; Male; MAP Kinase Kinase Kinases; Melanoma; Membrane Proteins; Middle Aged; Neoplasm Metastasis; Oncogene Proteins, Fusion; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Skin Neoplasms; Treatment Outcome

We investigated the efficacy of the Wee1 inhibitor MK-1775 in combination with radiation for the treatment of pediatric high-grade gliomas (HGGs), including diffuse intrinsic pontine gliomas (DIPGs).. Gene expression analysis was performed for 38 primary pediatric gliomas (3 grade I, 10 grade II, 11 grade III, 14 grade IV) and 8 normal brain samples using the Agilent 4 × 44 K array. Clonogenic survival assays were carried out in pediatric and adult HGG cell lines (n = 6) to assess radiosensitizing effects of MK-1775. DNA repair capacity was evaluated by measuring protein levels of γ-H2AX, a marker of double strand DNA breaks. In vivo activity of MK-1775 with radiation was assessed in 2 distinct orthotopic engraftment models of pediatric HGG, including 1 derived from a genetically engineered mouse carrying a BRAF(V600E) mutation, and 1 xenograft model in which tumor cells were derived from a patient's DIPG.. Wee1 is overexpressed in pediatric HGGs, with increasing expression positively correlated with malignancy (P = .007 for grade III + IV vs I + II) and markedly high expression in DIPG. Combination treatment of MK-1775 and radiation reduced clonogenic survival and increased expression of γ-H2AX to a greater extent than achieved by radiation alone. Finally, combined MK-1775 and radiation conferred greater survival benefit to mice bearing engrafted, orthotopic HGG and DIPG tumors, compared with treatment with radiation alone (BRAF(V600E) model P = .0061 and DIPG brainstem model P = .0163).. Our results highlight MK-1775 as a promising new therapeutic agent for use in combination with radiation for the treatment of pediatric HGGs, including DIPG.

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Cell Death; Cell Line, Tumor; Chemoradiotherapy; Glioblastoma; Humans; Mice; Mice, Transgenic; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Glioblastoma; Humans; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones

Dabrafenib and trametinib were approved for use as monotherapies in BRAF-mutant metastatic melanoma by the U.S. Food and Drug Administration (FDA) in 2013, and most recently, their use in combination has received accelerated FDA approval. Both drugs target the mitogen-activated protein kinase (MAPK) pathway: dabrafenib selectively inhibits mutant BRAF that constitutively activates the pathway, and trametinib selectively inhibits MEK1 and MEK2 proteins activated by RAF kinases. The phase III study of dabrafenib in BRAF(V600E) metastatic melanoma reported rapid tumor regression in most patients and a 59% objective RECIST response rate. The median progression-free survival (PFS) and overall survival (OS) were improved compared with dacarbazine. Toxicities were well tolerated and different from those reported for vemurafenib, the first FDA-approved BRAF inhibitor. Efficacy has been demonstrated in other BRAF-mutant genotypes. The phase III study of trametinib in BRAF inhibitor-naïve patients with BRAF(V600E) or BRAF(V600K) also showed benefit with a prolonged median PFS and OS compared with chemotherapy. Trametinib is ineffective in patients who have progressed on BRAF inhibitors. A phase II trial of combined dabrafenib and trametinib demonstrated higher response rates and longer median PFS than dabrafenib monotherapy, with less cutaneous toxicity. Here, we review the clinical development of both drugs as monotherapies and in combination, and discuss their role in the management of BRAF-mutant melanoma.

Topics: Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Disease-Free Survival; Exanthema; Fatigue; Humans; Imidazoles; Melanoma; Mutation; Oximes; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Pyridones; Pyrimidinones; Treatment Outcome

Brain metastases are a major cause of mortality in patients with advanced melanoma. Adequate brain distribution of targeted agents for melanoma will be critical for treatment success. Recently, improvement in overall survival led to US Food and Drug Administration (FDA) approval of the v-raf murine sarcoma viral oncogene homolog B (BRAF) inhibitors, vemurafenib and dabrafenib, and the mitogen-activated protein kinase kinase-1 (MEK)-1/2 inhibitor, trametinib. However, brain metastases and emergence of resistance remain a significant problem. MEK-1/2 is downstream of BRAF in the mitogen-activated protein kinase (MAPK) signaling pathway, making it an attractive target to combat resistance. The recently approved combination of dabrafenib and trametinib has shown improvement in progression-free survival; however, adequate brain distribution of both compounds is required to effectively treat brain metastases. In previous studies, we found limited brain distribution of dabrafenib. The purpose of the current study was to investigate factors influencing the brain distribution of trametinib. In vitro studies indicated that trametinib is a substrate for both P-glycoprotein (P-gp) and Bcrp, efflux transporters found at the blood-brain barrier. In vivo studies in transgenic mouse models confirmed that P-gp plays an important role in restricting brain distribution of trametinib. The brain-to-plasma partition coefficient (AUCbrain/AUCplasma) was approximately 5-fold higher in Mdr1a/b((-/-)) (P-gp knockout) and Mdr1a/b((-/-))Bcrp1((-/-)) (triple knockout) mice when compared with wild-type and Bcrp1((-/-)) (Bcrp knockout) mice. The brain distribution of trametinib was similar between the wild-type and Bcrp knockout mice. These results show that P-gp plays an important role in limiting brain distribution of trametinib and may have important implications for use of trametinib as single agent or in combination therapy for treatment of melanoma brain metastases.

Topics: Animals; Area Under Curve; ATP Binding Cassette Transporter, Subfamily B; ATP-Binding Cassette Transporters; Biological Transport; Blood-Brain Barrier; Brain Neoplasms; Combined Modality Therapy; Dogs; Madin Darby Canine Kidney Cells; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Melanoma; Mice; Mice, Knockout; Mice, Transgenic; Plasma; Protein Kinase Inhibitors; Pyridones; Pyrimidinones

Although diacylglycerol kinase α (DGKα) has been linked to several signaling pathways related to cancer cell biology, it has been neglected as a target for cancer therapy. The attenuation of DGKα activity via DGKα-targeting siRNA and small-molecule inhibitors R59022 and R59949 induced caspase-mediated apoptosis in glioblastoma cells and in other cancers, but lacked toxicity in noncancerous cells. We determined that mTOR and hypoxia-inducible factor-1α (HIF-1α) are key targets of DGKα inhibition, in addition to its regulation of other oncogenes. DGKα regulates mTOR transcription via a unique pathway involving cyclic AMP. Finally, we showed the efficacy of DGKα inhibition with short hairpin RNA or a small-molecule agent in glioblastoma and melanoma xenograft treatment models, with growth delay and decreased vascularity. This study establishes DGKα as a central signaling hub and a promising therapeutic target in the treatment of cancer.

Topics: Apoptosis; Brain Neoplasms; Cell Line, Tumor; Diacylglycerol Kinase; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Molecular Targeted Therapy; Piperidines; Pyrimidinones; Quinazolinones; RNA, Small Interfering; Thiazoles

The purpose of this study was to determine the capacity of MK-1775, a potent Wee-1 inhibitor, to abrogate the radiation-induced G(2) checkpoint arrest and modulate radiosensitivity in glioblastoma cell models and normal human astrocytes. The radiation-induced checkpoint response of established glioblastoma cell lines, glioblastoma neural stem (GNS) cells, and astrocytes were determined in vitro by flow cytometry and in vivo by mitosis-specific staining using immunohistochemistry. Mechanisms underlying MK-1775 radiosensitization were determined by mitotic catastrophe and γH2AX expression. Radiosensitivity was determined in vitro by the clonogenic assay and in vivo by tumor growth delay. MK-1775 abrogated the radiation-induced G(2) checkpoint and enhanced radiosensitivity in established glioblastoma cell lines in vitro and in vivo, without modulating radiation response in normal human astrocytes. MK-1775 appeared to attenuate the early-phase of the G(2) checkpoint arrest in GNS cell lines, although the arrest was not sustained and did not lead to increased radiosensitivity. These results show that MK-1775 can selectively enhance radiosensitivity in established glioblastoma cell lines. Further work is required to determine the role Wee-1 plays in checkpoint activation of GNS cells.

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; G2 Phase Cell Cycle Checkpoints; Glioblastoma; Humans; Mice; Mice, Nude; Molecular Targeted Therapy; Nuclear Proteins; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Radiation Tolerance; Radiation-Sensitizing Agents; Up-Regulation; Xenograft Model Antitumor Assays