scholarly journals PTEN Status Alters the Molecular Route to Resistance to BRAF Inhibitor in Melanoma

2019 ◽  
pp. 1-3
Author(s):  
Qiang Zuo ◽  
Yanlin Yu
Keyword(s):  
Mapk Pathway ◽  
Acquired Resistance ◽  
Braf Inhibitor ◽  
Mek Inhibitor ◽  
Mapk Signaling ◽  
Acquired Drug Resistance ◽  
Survival Pathway ◽  
Clinical Benefits ◽  
Dual Inhibitors ◽  
Melanoma Patients

Although targeted treatment by BRAF inhibitors (BRAFi) achieved a remarkable clinical response for patients with BRAF mutation, the strength of efficacy is short and limited by acquired drug resistance [1]. Recent studies identified many mechanisms of acquired resistance to BRAFi, such as mutations in NRAS or MEK1 and overexpression of COT, EGFR, PDGFRβ, IGF1R or MET, lead the reactivation of MAPK pathway and drive the cell proliferation, suggesting that co-targeting this hyperactivated survival pathway by combination inhibitors might gain the maximum clinical benefits for melanoma patients [2]. Based on these findings, FDA approved the combination of dabrafenib (BRAFi) with trametinib (MEK inhibitor) or vemurafenib (BRAFi) with cobimetinib (MEK inhibitor) to inhibit the MAPK signaling pathway in 2014 and 2015 more effectively. Indeed, the dual inhibitors of MEK and mutant BRAF kinases have shown a higher overall survival rate and exciting results in initial tumor response in clinical.

scholarly journals Vemurafenib resistant melanoma cells acquire mesenchymal stem cell-like properties

2019 ◽  
Vol 6 (4) ◽  
pp. 47-57
Author(s):  
A. A. Vartanian ◽  
O. S. Burova ◽  
Kh. S. Vishnyakova ◽  
I. V. Samoylenko ◽  
V. A. Misyurin ◽  
...  
Keyword(s):  
Cell Lines ◽  
Melanoma Cell ◽  
Acquired Resistance ◽  
Melanoma Cells ◽  
Mapk Signaling ◽  
Brafv600e Mutation ◽  
Acquired Drug Resistance ◽  
Melanoma Patients ◽  
Braf Mutant ◽  
Melanoma Cell Lines

Background. Activating mutations in the BRAF gene leads to a constitutive activation of the MAPK signaling. The highly selective BRAFV600E inhibitor, vemurafenib, improves the overall survival of BRAF-mutant melanoma patients. However, despite the excellent results of response rate, the average duration of the response was short and acquired resistance develops in most BRAF mutated melanoma patients within a few months. Objective: to derive melanoma cell lines from surgical species of patients with BRAF mutant melanomas resistant to vemurafenib and to elucidate the mechanisms involved in acquired drug resistance.Materials and methods. Mel Ki and Mel F1702 melanoma cells were obtained from metastases of disseminated melanoma patients with BRAFV600E mutation. 2D tumor cell culture, MTT test, immunicytochemistry, flow cytometry, real-time polimerase chain reaction and osteogenic and adipocytic differentiation were used in the study.Results. We have derived two melanoma cell lines Mel Ki and Mel F1702 from tumor samples of patients with BRAFV600E mutation resistant to vemurafenib. These cells were homogenous and had fibroblastic morphology. The IC50 values for Mel Ki and Mel F1702 were 4.7 and 6.3 μM, respectively. The expression of cancer-testis antigens was not detected in both types of cells suggesting the stemness of Mel Ki and Mel F1702 melanoma cells. The immunophenotypic profile of the vemurafenib resistsant melanoma cells showed the expression of typical mesenchymal stem cells markers such as CD90, CD105 and CD44. In addition, we found that the melanoma cell lines derived from tumor resistant to vemurafenib differentiated into osteoblastand adipocyte-like cells. Conclusion. In this study we are offering an experimental evidence of the phenotypic transition of the vemurafenib-resistant melanoma cells into mesenchymal stem-like cells.

scholarly journals A screen for combination therapies inBRAF/NRASwild type melanoma identifies nilotinib plus MEK inhibitor as a synergistic combination

2017 ◽  
Author(s):  
Marco Ranzani ◽  
Kristel Kemper ◽  
Magali Michaut ◽  
Oscar Krijgsman ◽  
Nanne Aben ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Genome Wide ◽  
Melanoma Patients ◽  
Inhibitor Combination

AbstractDespite recent therapeutic advances in the management ofBRAFV600-mutant melanoma, there is still a compelling need for more effective treatments for patients who developedBRAF/NRASwild type disease. Since the activity of single targeted agents is limited by innate and acquired resistance, we performed a high-throughput drug screen using 180 drug combinations to generate over 18,000 viability curves, with the aim of identifying agents that synergise to killBRAF/NRASwild type melanoma cells. From this screen we observed strong synergy between the tyrosine kinase inhibitor nilotinib and MEK inhibitors and validated this combination in an independent cell line collection. We found that AXL expression was associated with synergy to the nilotinib/MEK inhibitor combination, and that both drugs work in concert to suppress pERK. This finding was supported by genome-wide CRISPR screening which revealed that resistance mechanisms converge on regulators of the MAPK pathway. Finally, we validated the synergy of nilotinib/trametinib combinationin vivousing patient-derived xenografts. Our results indicate that a nilotinib/MEK inhibitor combination may represent an effective therapy inBRAF/NRASwild type melanoma patients.

Pharmacodynamic Effects and Mechanisms of Resistance to Vemurafenib in Patients With Metastatic Melanoma

2013 ◽  
Vol 31 (14) ◽  
pp. 1767-1774 ◽  
Author(s):  
Kerstin Trunzer ◽  
Anna C. Pavlick ◽  
Lynn Schuchter ◽  
Rene Gonzalez ◽  
Grant A. McArthur ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Metastatic Melanoma ◽  
Cell Cycle Progression ◽  
Mapk Pathway ◽  
Objective Response ◽  
Acquired Resistance ◽  
Braf Inhibitor ◽  
Mapk Signaling ◽  
Cycle Progression ◽  
Pharmacodynamic Effects

Purpose To assess pharmacodynamic effects and intrinsic and acquired resistance mechanisms of the BRAF inhibitor vemurafenib in BRAFV600-mutant melanoma, leading to an understanding of the mechanism of action of vemurafenib and ultimately to optimization of metastatic melanoma therapy. Methods In the phase II clinical study NP22657 (BRIM-2), patients received oral doses of vemurafenib (960 mg twice per day). Serial biopsies were collected to study changes in mitogen-activated protein kinase (MAPK) signaling, cell-cycle progression, and factors causing intrinsic or acquired resistance by immunohistochemistry, DNA sequencing, or somatic mutation profiling. Results Vemurafenib inhibited MAPK signaling and cell-cycle progression. An association between the decrease in extracellular signal-related kinase (ERK) phosphorylation and objective response was observed in paired biopsies (n = 22; P = .013). Low expression of phosphatase and tensin homolog showed a modest association with lower response. Baseline mutations in MEK1P124 coexisting with BRAFV600 were noted in seven of 92 samples; their presence did not preclude objective tumor responses. Acquired resistance to vemurafenib associated with reactivation of MAPK signaling as observed by elevated ERK1/2 phosphorylation levels in progressive lesions and the appearance of secondary NRASQ61 mutations or MEK1Q56P or MEK1E203K mutations. These two activating MEK1 mutations had not previously been observed in vivo in biopsies of progressive melanoma tumors. Conclusion Vemurafenib inhibits tumor proliferation and oncogenic BRAF signaling through the MAPK pathway. Acquired resistance results primarily from MAPK reactivation driven by the appearance of secondary mutations in NRAS and MEK1 in subsets of patients. The data suggest that inhibition downstream of BRAF should help to overcome acquired resistance.

scholarly journals Triple blockade of EGFR, MEK and PD-L1 has antitumor activity in colorectal cancer models with constitutive activation of MAPK signaling and PD-L1 overexpression

2019 ◽  
Vol 38 (1) ◽  
Author(s):  
S. Napolitano ◽  
N. Matrone ◽  
A. L. Muddassir ◽  
G. Martini ◽  
A. Sorokin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Molecular Mechanisms ◽  
Mapk Pathway ◽  
Combined Treatment ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Gene Signature ◽  
Mapk Signaling

Abstract Background Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic colorectal cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Nevertheless, even if inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance, its use is limited by the development of MEK inhibitor (MEKi) resistance. Methods We have generated in vitro and in vivo different CRC models in order to underline the mechanisms of MEKi resistance. Results The three different in vitro MEKi resistant models, two generated by human CRC cells quadruple wild type for KRAS, NRAS, BRAF, PI3KCA genes (SW48-MR and LIM1215-MR) and one by human CRC cells harboring KRAS mutation (HCT116-MR) showed features related to the gene signature of colorectal cancer CMS4 with up-regulation of immune pathway as confirmed by microarray and western blot analysis. In particular, the MEKi phenotype was associated with the loss of epithelial features and acquisition of mesenchymal markers and morphology. The change in morphology was accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently to RAS mutation status. To extend these in vitro findings, we have obtained mouse colon cancer MC38- and CT26-MEKi resistant syngeneic models (MC38-MR and CT26-MR). Combined treatment with MEKi, EGFR inhibitor (EGFRi) and PD-L1 inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both models. Conclusions These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with EGFR and PD-L1 inhibitors via modulation of host immune responses.

scholarly journals DDRE-07. DIPG HARBOUR ALTERATIONS TARGETABLE BY MEK INHIBITORS, WITH ACQUIRED RESISTANCE MECHANISMS OVERCOME BY COMBINATORIAL INHIBITION

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii62-ii62
Author(s):  
Elisa Izquierdo ◽  
Diana Carvalho ◽  
Alan Mackay ◽  
Sara Temelso ◽  
Jessica K R Boult ◽  
...  
Keyword(s):  
Drug Exposure ◽  
Mapk Pathway ◽  
Synergistic Effects ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Mesenchymal Transition

Abstract The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In the era of precision medicine, targeted therapies represent an exciting treatment opportunity, yet resistance can rapidly emerge, playing an important role in treatment failure. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling (methylation BeadArray, exome, RNAseq, phospho-proteomics) linked to drug screening in newly-established patient-derived models of DIPG in vitro and in vivo. We identified a high degree of in vitro sensitivity to the MEK inhibitor trametinib (GI50 16-50nM) in samples, which harboured genetic alterations targeting the MAPK pathway, including the non-canonical BRAF_G469V mutation, and those affecting PIK3R1 and NF1. However, treatment of PDX models and of a patient with trametinib at relapse failed to elicit a significant response. We generated trametinib-resistant clones (62-188-fold, GI50 2.4–5.2µM) in the BRAF_G469V model through continuous drug exposure, and identified acquired mutations in MEK1/2 (MEK1_K57N, MEK1_I141S and MEK2_I115N) with sustained pathway up-regulation. These cells showed the hallmarks of mesenchymal transition, and expression signatures overlapping with inherently trametinib-insensitive primary patient-derived cells that predicted an observed sensitivity to dasatinib. Combinations of trametinib with dasatinib and the downstream ERK inhibitor ulixertinib showed highly synergistic effects in vitro. These data highlight the MAPK pathway as a therapeutic target in DIPG, and show the importance of parallel resistance modelling and rational combinatorial treatments likely to be required for meaningful clinical translation.

scholarly journals Combined BRAF and MEK Inhibition with Vemurafenib and Cobimetinib for Patients with Advanced Melanoma

2017 ◽  
Vol 13 (01) ◽  
pp. 1
Author(s):  
Antonio M Grimaldi ◽  
Ester Simeone ◽  
Lucia Festino ◽  
Vito Vanella ◽  
Paolo A Ascierto ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Combined Therapy ◽  
Acquired Resistance ◽  
Braf Inhibitor ◽  
Progression Free Survival ◽  
Standard Of Care ◽  
Phase Iii ◽  
Free Survival ◽  
Mek Inhibition ◽  
Braf Mutant

Acquired resistance is the most common cause of BRAF inhibitor monotherapy treatment failure, with the majority of patients experiencing disease progression with a median progression-free survival of 6-8 months. As such, there has been considerable focus on combined therapy with dual BRAF and MEK inhibition as a means to improve outcomes compared with monotherapy. In the COMBI-d and COMBI-v trials, combined dabrafenib and trametinib was associated with significant improvements in outcomes compared with dabrafenib or vemurafenib monotherapy, in patients with BRAF-mutant metastatic melanoma. The combination of vemurafenib and cobimetinib has also been investigated. In the phase III CoBRIM study in patients with unresectable stage III-IV BRAF-mutant melanoma, treatment with vemurafenib and cobimetinib resulted in significantly longer progression-free survival and overall survival (OS) compared with vemurafenib alone. One-year OS was 74.5% in the vemurafenib and cobimetinib group and 63.8% in the vemurafenib group, while 2-year OS rates were 48.3% and 38.0%, respectively. The combination was also well tolerated, with a lower incidence of cutaneous squamous-cell carcinoma and keratoacanthoma compared with monotherapy. Dual inhibition of both MEK and BRAF appears to provide a more potent and durable anti-tumour effect than BRAF monotherapy, helping to prevent acquired resistance as well as decreasing adverse events related to BRAF inhibitor-induced activation of the MAPK-pathway. Combined BRAF and MEK inhibition is the standard of care in patients with advanced BRAF-mutant melanoma.

scholarly journals LGG-26. DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR (DLGNT) IN CHILDREN: DIFFERENT CLINICAL PRESENTATIONS AND OUTCOMES

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii371-iii371
Author(s):  
Andge Valiakhmetova ◽  
Ludmila Papusha ◽  
Ludmila Yasko ◽  
Alexander Druy ◽  
Alexander Karachunsky ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Braf Inhibitor ◽  
Complete Response ◽  
Mek Inhibitor ◽  
Braf V600e ◽  
Glioneuronal Tumor ◽  
Low Grade ◽  
Conventional Chemotherapy ◽  
Diffuse Leptomeningeal Glioneuronal Tumor ◽  
Braf Fusion

Abstract Diffuse leptomeningeal glioneuronal tumor (DLGNT) is an extremely rare disease, newly recognized in the 2016 WHO classification of tumors of the CNS. Most DLGNTs are low-grade neuroepithelial tumors with variable elements of neuronal/neurocytic and glial differentiation, have diffuse leptomeningeal enhancement on MRI, and typically harbor KIAA1549-BRAF fusions. Other alterations, such as the BRAF V600E substitution, are less common. Here, we present three cases of DLGNT with different presentations and outcomes. The first patient is a 2yr-old male with KIAA1549-BRAF fusion, and was treated with Carbo/VCR chemotherapy after a biopsy, with resultant ongoing stable disease for 3.5 years. The second patient, an 8yr-old male had the BRAF V600E point mutation and was treated with conventional chemotherapy (VCR/carboplatin). On progression, he received the BRAF inhibitor vemurafenib, achieving a complete response which last 14 month. The third patient, a 27 month old male, harbored a KIAA1549-BRAF fusion and was treated at diagnosis with the MEK inhibitor trametinib. The tumor has been radiographically stable in the context of clinical improvement for 21 months since the treatment initiation, ongoing 24 month. In summary, we present further evidence of MAPK pathway alterations in children with DLGNT. We describe a range of molecular presentations and clinical outcomes, including one patient treated with conventional chemotherapy with further stabilization of disease during 3.5 years and two patients who were successfully treated with targeted therapy.

scholarly journals An adaptive signaling network in melanoma inflammatory niches confers tolerance to MAPK signaling inhibition

2017 ◽  
Vol 214 (6) ◽  
pp. 1691-1710 ◽  
Author(s):  
Helen L. Young ◽  
Emily J. Rowling ◽  
Mattia Bugatti ◽  
Emanuele Giurisato ◽  
Nadia Luheshi ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Acquired Resistance ◽  
Drug Tolerance ◽  
Mapk Signaling ◽  
Signaling Network ◽  
Mitogen Activated Protein Kinase ◽  
Cytokine Signaling ◽  
Adaptive Responses ◽  
Mapk Inhibitors

Mitogen-activated protein kinase (MAPK) pathway antagonists induce profound clinical responses in advanced cutaneous melanoma, but complete remissions are frustrated by the development of acquired resistance. Before resistance emerges, adaptive responses establish a mutation-independent drug tolerance. Antagonizing these adaptive responses could improve drug effects, thereby thwarting the emergence of acquired resistance. In this study, we reveal that inflammatory niches consisting of tumor-associated macrophages and fibroblasts contribute to treatment tolerance through a cytokine-signaling network that involves macrophage-derived IL-1β and fibroblast-derived CXCR2 ligands. Fibroblasts require IL-1β to produce CXCR2 ligands, and loss of host IL-1R signaling in vivo reduces melanoma growth. In tumors from patients on treatment, signaling from inflammatory niches is amplified in the presence of MAPK inhibitors. Signaling from inflammatory niches counteracts combined BRAF/MEK (MAPK/extracellular signal–regulated kinase kinase) inhibitor treatment, and consequently, inhibiting IL-1R or CXCR2 signaling in vivo enhanced the efficacy of MAPK inhibitors. We conclude that melanoma inflammatory niches adapt to and confer drug tolerance toward BRAF and MEK inhibitors early during treatment.

Achievements and Challenges of Molecular Targeted Therapy in Melanoma

2015 ◽  
pp. 177-186 ◽  
Author(s):  
Ryan Sullivan ◽  
Patricia LoRusso ◽  
Scott Boerner ◽  
Reinhard Dummer
Keyword(s):  
Tumor Suppressor ◽  
Mapk Pathway ◽  
Single Agent ◽  
Braf Inhibitor ◽  
Clinical Trial Data ◽  
Great Majority ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Loss Of Function ◽  
Early Clinical Trial

The treatment of melanoma has been revolutionized over the past decade with the development of effective molecular and immune targeted therapies. The great majority of patients with melanoma have mutations in oncogenes that predominantly drive signaling through the mitogen activated protein kinase (MAPK) pathway. Analytic tools have been developed that can effectively stratify patients into molecular subsets based on the identification of mutations in oncogenes and/or tumor suppressor genes that drive the MAPK pathway. At the same time, potent and selective inhibitors of mediators of the MAPK pathway such as RAF, MEK, and ERK have become available. The most dramatic example is the development of single-agent inhibitors of BRAF (vemurafenib, dabrafenib, encorafenib) and MEK (trametinib, cobimetinib, binimetinib) for patients with metastatic BRAFV600-mutant melanoma, a subset that represents 40% to 50% of patients with metastatic melanoma. More recently, the elucidation of mechanisms underlying resistance to single-agent BRAF inhibitor therapy led to a second generation of trials that demonstrated the superiority of BRAF inhibitor/MEK inhibitor combinations (dabrafenib/trametinib; vemurafenib/cobimetinib) compared to single-agent BRAF inhibitors. Moving beyond BRAFV600targeting, a number of other molecular subsets—such as mutations in MEK, NRAS, and non-V600 BRAF and loss of function of the tumor suppressor neurofibromatosis 1 ( NF1)—are predicted to respond to MAPK pathway targeting by single-agent pan-RAF, MEK, or ERK inhibitors. As these strategies are being tested in clinical trials, preclinical and early clinical trial data are now emerging about which combinatorial approaches might be best for these patients.

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