BRAF inhibitors: the current and the future

Rapid but nondurable response of a BRAF exon 15 double-mutated spindle cell sarcoma to a combination of BRAF and MEK inhibitors

INTRODUCTION

BRAF V600E substitution predicts sensitivity of a cancer to BRAF inhibitor therapy. The mutation is rarely found in soft-tissue sarcomas. Here we describe a case of undifferentiated spindle cell sarcoma showing primary insensitivity to standard chemotherapy and pronounced but non-sustained response to BRAF/MEK inhibitors at recurrence.

CASE PRESENTATION

A 13-year-old girl was diagnosed with low-grade spindle cell sarcoma of pelvic localization, BRAF exon 15 double-mutated: c.1799T>A p.V600E and c.1819T>A p.S607T in cis-position. The tumor showed resistance to CWS-based first-line chemotherapy and was treated surgically by radical resection. Seven months after surgery the patient developed metastatic relapse with abdominal carcinomatosis. Combined targeted therapy with BRAF/MEK inhibitors afforded complete response in 1 month and was continued, though complicated by severe side effects (fever, rash) necessitating 1-2 week toxicity breaks. After 4 months from commencement the disease recurred and anti-BRAF/MEK regimen consolidation was unsuccessful. Intensive salvation chemotherapy was ineffective. Empirical immunotherapy afforded a transient partial response giving way to fatal progression with massive, abdominal cocoon-complicated peritoneal carcinomatosis.

CONCLUSION

This is the first report of spindle cell sarcoma BRAF V600E/S607T double-mutated, responding to a combination of B-Raf and MEK inhibitors. Despite the low histological grade and radical surgical treatment of the tumor at primary manifestation, the disease had aggressive clinical course and the response to BRAF/MEK targeted therapy at recurrence was complete but nondurable. Empirical use of pembrolizumab provided no unambiguous evidence on the clinical relevance of immunotherapy in protein kinase -rearranged spindle cell tumors.

BRAF Inhibitors in Metastatic Colorectal Cancer and Mechanisms of Resistance: A Review of the Literature

Metastatic colorectal cancer (mCRC) with mutated BRAF exhibits distinct biological and molecular features that set it apart from other subtypes of CRC. Current standard treatment for these tumors involves a combination of chemotherapy (CT) and VEGF inhibitors. Recently, targeted therapy against BRAF and immunotherapy (IT) for cases with microsatellite instability (MSI) have been integrated into clinical practice. While targeted therapy has shown promising results, resistance to treatment eventually develops in a significant portion of responsive patients. This article aims to review the available literature on mechanisms of resistance to BRAF inhibitors (BRAFis) and potential therapeutic strategies to overcome them.

An updated literature on BRAF inhibitors (2018-2023)

BRAF is the most common serine-threonine protein kinase and regulates signal transduction from RAS to MEK inside the cell. The BRAF is a highly active isoform of RAF kinase. BRAF has two domains such as regulatory and kinase domains. The BRAF inhibitors bind in the c-terminus of the kinase domain and inhibit the downstream pathways. The mutation occurs mainly in the A-loop of the kinase domain. The mutation occurs due to a conversion of valine to glutamate/lysine/arginine/aspartic acid at 600th position. Among the diverse mutations, BRAF^V600E is the most common and responsible for numerous cancer such as melanoma, colorectal, ovarian, and thyroid cancer. Due to mutations in RAC1, loss of PTEN, NF1, CCND1, USP28-FBW7 complex, COT overexpression, and CCND1 amplification, the BRAF kinase enzyme developed resistance over the commercially available BRAF inhibitors. There is still unmute urgence for the development of BRAF inhibitors to overcome the persistent limitation such as resistance, mutation, and adverse effects of drugs. In the current study, we described the structure, activation, downstream signaling pathway, and mutation of BRAF. Our group also provided a detailed review of BRAF inhibitors from the last five years (2018-2023) highlighting the structure-activity relationship, mechanistic study, and molecular docking studies. We hope that the current analysis will be a useful resource for researchers and provide chemists a glimpse into the future as design and development of more effective and secure BRAF kinase inhibitors. The development of BRAF inhibitors to overcome the persistent limitation such as resistance, mutation, and adverse effects of drugs. In depth description about different heterocyclic scaffolds (quinoline, imidazole, pyridine, triazole, pyrrole etc.) as BRAF inhibitors from the last five years (2018-2023) highlighting the structure-activity relationship, mechanistic study, and molecular docking studies.

Computational analysis of natural product B-Raf inhibitors

B-Raf protein is a serine-threonine kinase and an important signal transduction molecule of the MAPK signaling pathway that mediates signals from RAS to MEK, ultimately promoting various essential cellular functions. The B-Raf kinase domain is divided into two subdomains: a small N-terminal lobe and a large C-terminal lobe, with a deep catalytic cleft between them. The N-terminal lobe contains a phosphate-binding loop (P-loop) and nucleotide-binding pocket, while the C-terminal lobe binds the protein substrates and contains the catalytic loop. The ligand pharmacophore was generated by using 17 different natural products and the receptor pharmacophore was generated by using protein structures. The reported natural product B-Raf inhibitors were analyzed according to the pharmacophore analysis (HipHop fit), virtual screening tools by Lipinski's rule of five. Thirteen out of seventeen molecules share the best ligand based pharmacophoric model (HipHop_5). The best receptor based pharmacophoric model came as AADHR. The compounds were docked against the B-Raf receptors (PDB ID: 3OG7, 4XV2, 5C9C). The compound DHSilB with cDOCKER interaction energy of -62.7 kcal/mol, -83.3 kcal/mol, -73.6 kcal/mol as well as the compound DHSilA with cDOCKER interaction energy of -63.9 kcal/mol, -63.2 kcal/mol, -74.7 kcal/mol showed satisfactory interaction with the respective receptors. Finally, the MD simulation was run for 100 ns for the top docked compounds DHSilA and DHSilB with the B-Raf proteins (PDB ID: 3OG7, 4XV2 and 5C9C). After the MD simulation run for 100 ns, the ligand 2,3-dehydrosilybin A (DHSilA) was found to be more stable in terms of the trajectories of RMSD, RMSF, Rg and H-bonds.

Incidence of BRAF V600E Gene Mutation Among Lebanese Population in Melanoma and Colorectal Cancer: A Retrospective Study Between 2010 and 2019

Introduction: Cancers arise owing to the accumulation of mutations in critical genes that leads to uncontrolled cell division and the avoidance of apoptosis. Among these oncogenes, BRAF is a potent mitogen-activated protein kinase (MAPK) pathway activator known to be somatically mutated by a glutamic acid to valine substitution at codon 600 (V600E). It is a common finding in various types of human cancers, including malignant melanoma and colorectal cancer (CRC), and is considered a poor prognostic factor and a predictive biomarker. The study aims to determine the incidence of BRAF V600E gene mutation in Lebanese patients with melanoma and CRC and its correlation with gender and age.

Methods: We conducted a retrospective cohort design study in which 210 and 132 patients diagnosed to have melanoma and CRC, respectively, were recruited from 2010 to 2019 from "L’Institut National de Pathologie," where a specific polymerase chain reaction is used to detect BRAF mutations. Data from digitized records were collected, including demographic characteristics (age and gender), cancer type, and BRAF mutation. The collected data were analyzed using SPSS Statistics version 20.0 (IBM Corp., Armonk, NY). A p-value < 0.05 was considered significant.

Results: The incidence of BRAF mutation in melanoma is 88.10%. There is female predominance with a ratio of 2.6:1 (p = 0.240) and the majority of patients aged between 40 and 60 years (51.2%) with a mean age of 53.74 years. While in CRC, BRAF is mutated in 7.5% with a ratio of 1.2:1 of male predominance (p = 0.999). The majority of patients (54.8%) were between the ages of 60 and 80 years, with a mean age of 65.5 years.

Conclusion: BRAF is a frequent oncogenic mutation that is found in lethal tumors. Targeted therapies for these cancers interfere with developing more effective therapeutic strategies, which affect the treatment response in BRAF mutants and improve the prognosis of the patients.

BRAF mutation in colorectal cancer: An update

Colon cancer is a leading cause of cancer-related deaths worldwide. About 10% of all colon cancer patients are found to have a mutation in BRAF proto-oncogene that arise as a result of a substitution of amino acid valine with glutamate at position 600 (V600E). This specific mutation is also found in melanomas, but at even higher percent - in up to 60% of patients. A particular category of drugs called BRAF inhibitors, have been developed in order to increase survival. But, while in patients with melanoma this class of drugs work well especially when combined with mitogen-activated protein kinase inhibitors, they have low efficacy in patients with metastatic colorectal cancer suggesting different mechanism of action and development of drug resistance. This review summarise recent findings aimed to highlight events in BRAF mutations in metastatic colorectal cancer.

Mutations in key driver genes of pancreatic cancer: molecularly targeted therapies and other clinical implications

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a minimal difference between its incidence rate and mortality rate. Advances in oncology over the past several decades have dramatically improved the overall survival of patients with multiple cancers due to the implementation of new techniques in early diagnosis, therapeutic drugs, and personalized therapy. However, pancreatic cancers remain recalcitrant, with a 5-year relative survival rate of <9%. The lack of measures for early diagnosis, strong resistance to chemotherapy, ineffective adjuvant chemotherapy and the unavailability of molecularly targeted therapy are responsible for the high mortality rate of this notorious disease. Genetically, PDAC progresses as a complex result of the activation of oncogenes and inactivation of tumor suppressors. Although next-generation sequencing has identified numerous new genetic alterations, their clinical implications remain unknown. Classically, oncogenic mutations in genes such as KRAS and loss-of-function mutations in tumor suppressors, such as TP53, CDNK2A, DPC4/SMAD4, and BRCA2, are frequently observed in PDAC. Currently, research on these key driver genes is still the main focus. Therefore, studies assessing the functions of these genes and their potential clinical implications are of paramount importance. In this review, we summarize the biological function of key driver genes and pharmaceutical targets in PDAC. In addition, we conclude the results of molecularly targeted therapies in clinical trials and discuss how to utilize these genetic alterations in further clinical practice.

Melanoma Cell Resistance to Vemurafenib Modifies Inter-Cellular Communication Signals

The therapeutic success of BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) in BRAF-mutant melanoma is limited by the emergence of drug resistance, and several lines of evidence suggest that changes in the tumor microenvironment can play a pivotal role in acquired resistance. The present study focused on secretome profiling of melanoma cells sensitive or resistant to the BRAFi vemurafenib. Proteomic and cytokine/chemokine secretion analyses were performed in order to better understand the interplay between vemurafenib-resistant melanoma cells and the tumor microenvironment. We found that vemurafenib-resistant melanoma cells can influence dendritic cell (DC) maturation by modulating their activation and cytokine production. In particular, human DCs exposed to conditioned medium (CM) from vemurafenib-resistant melanoma cells produced higher levels of pro-inflammatory cytokines—that potentially facilitate melanoma growth—than DCs exposed to CM derived from parental drug-sensitive cells. Bioinformatic analysis performed on proteins identified by mass spectrometry in the culture medium from vemurafenib-sensitive and vemurafenib-resistant melanoma cells suggests a possible involvement of the proteasome pathway. Moreover, our data confirm that BRAFi-resistant cells display a more aggressive phenotype compared to parental ones, with a significantly increased production of interferon-γ, interleukin-8, vascular-endothelial growth factor, CD147/basigin, and metalloproteinase 2 (MMP-2). Plasma levels of CD147/basigin and MMP-2 were also measured before the start of therapy and at disease progression in a small group of melanoma patients treated with vemurafenib or vemurafenib plus cobimetinib. A significant increment in CD147/basigin and MMP-2 was observed in all patients at the time of treatment failure, strengthening the hypothesis that CD147/basigin might play a role in BRAFi resistance.

Safety of BRAF+MEK Inhibitor Combinations: Severe Adverse Event Evaluation

Aim: The selective BRAF and MEK inhibitors (BRAFi+MEKi) have substantially improved the survival of melanoma patients with BRAF V600 mutations. However, BRAFi+MEKi can also cause severe or fatal outcomes. We aimed to identify and compare serious adverse events (sAEs) that are significantly associated with BRAFi+MEKi. Methods: In this pharmacovigilance study, we reviewed FDA Adverse Event Reporting System (FAERS) data in order to detect sAE reporting in patients treated with the combination therapies vemurafenib+cobimetinib (V+C), dabrafenib+trametinib (D+T) and encorafenib+binimetinib (E+B). We evaluated the disproportionate reporting of BRAFi+MEKi-associated sAEs. Significant associations were further analyzed to identify combination-specific safety signals among BRAFi+MEKi. Results: From January 2018 through June 2019, we identified 11,721 sAE reports in patients receiving BRAFi+MEKi. Comparison of BRAFi+MEKi combinations demonstrates that skin toxicities, including Stevens–Johnson syndrome, were disproportionally reported using V+C, with an age-adjusted reporting odds ratio (adj. ROR) of 3.4 (95%CI, 2.9–4.0), whereas fever was most significantly associated with D+T treatment with an adj. ROR of 1.9 (95%CI, 1.5–2.4). Significant associations using E+B treatment include peripheral neuropathies (adj. ROR 2.7; 95%CI, 1.2–6.1) and renal disorders (adj. ROR 4.1; 95%CI, 1.3–12.5). Notably, we found an increase in the proportion of Guillain–Barré syndrome reports (adj. ROR 8.5; 95%CI, 2.1–35.0) in patients administered E+B. Conclusion: BRAFi+MEKi combinations share a similar safety profile attributed to class effects, yet concomitantly, these combinations display distinctive effects that can dramatically impact patients’ health. Owing to the limitations of pharmacovigilance studies, some findings warrant further validation. However, the possibility of an increased risk for these events should be considered in patient care.

BRAF mutation and its inhibitors in sarcoma treatment

The mitogen‐activated protein kinase (MAPK) signaling pathway plays a significant role in mediating cellular physiological activities, such as proliferation, differentiation, apoptosis, and senescence. This signaling pathway is composed of several major proto‐oncogenes of RAS/RAF/MEK/ERK, among which the BRAF proto‐oncogene, as one of the three members of the RAF family, has a higher mutation rate than ARAF and CRAF and has attracted extensive attention. Regarding the BRAF mutation, approximately 95% of BRAF mutations belong to the BRAF V600E mutation, which can enhance the expression of the MAPK signaling pathway and is thus related to the occurrence and development of various malignant tumors and has been successfully identified as a therapeutic target. Moreover, drug resistance to BRAF inhibitor treatment also appears to be an important issue. Considering the successful use of BRAF inhibitors in melanoma, we provide a brief overview of the BRAF mutations, including their basic structures and activation mechanisms, and the new classification method for BRAF mutations. Most importantly, we summarize the results of BRAF inhibitor treatment in different sarcomas. To overcome drug resistance to BRAF inhibitor treatment, we also outline the different mechanisms of drug resistance to BRAF inhibitor treatment and introduce the combination strategy of BRAF inhibitors with other targeted therapies.

Actionable Strategies to Target Multiple Myeloma Plasma Cell Resistance/Resilience to Stress: Insights From "Omics" Research

While the modern therapeutic armamentarium to treat multiple myeloma (MM) patients allows a longer control of the disease, this second-most-frequent hematologic cancer is still uncurable in the vast majority of cases. Since MM plasma cells are subjected to various types of chronic cellular stress and the integrity of specific stress-coping pathways is essential to ensure MM cell survival, not surprisingly the most efficacious anti-MM therapy are those that make use of proteasome inhibitors and/or immunomodulatory drugs, which target the biochemical mechanisms of stress management. Based on this notion, the recently realized discoveries on MM pathobiology through high-throughput techniques (genomic, transcriptomic, and other "omics"), in order for them to be clinically useful, should be elaborated to identify novel vulnerabilities in this disease. This groundwork of information will likely allow the design of novel therapies against targetable molecules/pathways, in an unprecedented opportunity to change the management of MM according to the principle of "precision medicine." In this review, we will discuss some examples of therapeutically actionable molecules and pathways related to the regulation of cellular fitness and stress resistance in MM.

Myosin II Reactivation and Cytoskeletal Remodeling as a Hallmark and a Vulnerability in Melanoma Therapy Resistance

Despite substantial clinical benefit of targeted and immune checkpoint blockade-based therapies in melanoma, resistance inevitably develops. We show cytoskeletal remodeling and changes in expression and activity of ROCK-myosin II pathway during acquisition of resistance to MAPK inhibitors. MAPK regulates myosin II activity, but after initial therapy response, drug-resistant clones restore myosin II activity to increase survival. High ROCK-myosin II activity correlates with aggressiveness, identifying targeted therapy- and immunotherapy-resistant melanomas. Survival of resistant cells is myosin II dependent, regardless of the therapy. ROCK-myosin II ablation specifically kills resistant cells via intrinsic lethal reactive oxygen species and unresolved DNA damage and limits extrinsic myeloid and lymphoid immunosuppression. Efficacy of targeted therapies and immunotherapies can be improved by combination with ROCK inhibitors.

Genetic alterations in anaplastic thyroid carcinoma and targeted therapies

Thyroid cancer is the most common type of endocrine malignancy, and its incidence is increasing. Anaplastic thyroid cancer (ATC), referring to undifferentiated subtypes, is considered to be aggressive and associated with poor prognosis. Conventional therapies, including surgery, chemotherapy and radioiodine therapy, have been used for ATC, but these do not provide any significant reduction of the overall mortality rate. The tumorigenesis, development, dedifferentiation and metastasis of ATC are closely associated with the activation of various tyrosine cascades and inactivation of tumor suppressor genes, including B-Raf proto-oncogene, serine/threonine kinase^V600E, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α,tumor protein 53 mutations and telomerase reverse transcriptase mutation. These pathways exert their functions individually or through a complex network. Identification of these mutations may provide a deeper understanding of ATC. A variety of tyrosine kinase inhibitors have been successfully employed for controlling ATC growth in vitro and in xenografts. Certain novel compounds are still in clinical trials. Multi-kinase inhibitors provide a novel approach with great potential. This systematic review determined the prevalence of the major genetic alterations and their inhibitors in ATC.

BRAF inhibitors promote intermediate BRAF(V600E) conformations and binary interactions with activated RAS

Oncogenic BRAF mutations initiate tumor formation by unleashing the autoinhibited kinase conformation and promoting RAS-decoupled proliferative RAF-MEK-ERK signaling. We have engineered luciferase-based biosensors to systematically track full-length BRAF conformations and interactions affected by tumorigenic kinase mutations and GTP loading of RAS. Binding of structurally diverse αC-helix-OUT BRAF inhibitors (BRAFi) showed differences in specificity and efficacy by shifting patient mutation-containing BRAF reporters from the definitive opened to more closed conformations. Unexpectedly, BRAFi engagement with the catalytic pocket of V600E-mutated BRAF stabilized an intermediate and inactive kinase conformation that enhanced binary RAS:RAF interactions, also independently of RAF dimerization in melanoma cells. We present evidence that the interference with RAS interactions and nanoclustering antagonizes the sequential formation of drug-induced RAS:RAF tetramers. This suggests a previously unappreciated allosteric effect of anticancer drug-driven intramolecular communication between the kinase and RAS-binding domains of mutated BRAF, which may further promote paradoxical kinase activation and drug resistance mechanisms.

Effects of Copper Chelation on BRAFV600E Positive Colon Carcinoma Cells

High affinity copper binding to mitogen-activated protein kinase kinase 1 (MAP2K1, also known as MEK1) allosterically promotes the kinase activity of MEK1/2 on extracellular signal regulated kinases 1 and 2 (ERK1/2). Consequently, copper-dependent activation of the mitogen-activated (MAP) kinase pathway has a role in promoting tumor growth. Conversely, copper chelation may represent a possible therapeutic approach for a specific subset of tumors characterized by activating mutations in the serine/threonine protein kinase V-Raf Murine Sarcoma Viral Oncogene Homolog B1 (BRAF), such as the V600E, occurring within the kinase domain (BRAF^V600E). Tetrathiomolybdate (TM) is a specific copper chelating agent currently used for the treatment of Wilson’s disease and in preclinical studies for the management of metastatic cancers owing to its anti-angiogenic and anti-inflammatory properties. We evaluated in vitro and in vivo the effects of copper depletion achieved by pharmacological treatment with TM in human colorectal cells bearing the BRAF^V600E mutation in comparison with BRAF wild type cells. We provide evidence that selective copper chelation differentially affects proliferation, survival and migration of colon cancer cells bearing the BRAF^V600E mutation compared to BRAF^wt acting via differential phosphorylation levels of ERK1/2. Moreover, tetrathiomolybdate treatment was also effective in reducing the clonogenic potential of colon cancer BRAF^V600E cells resistant to BRAF pharmacological inhibition. In conclusion, these results support further assessment of copper chelation therapy as an adjuvant therapy for inhibiting the progression of colon cancers containing the BRAF^V600E mutation.

Discovery of 2-(aminopyrimidin-5-yl)-4-(morpholin-4-yl)-6- substituted triazine as PI3K and BRAF dual inhibitor

AIM

The discovery and development of novel agents simultaneously targeting PI3K/AKT/mammalian target of rapamycin and Ras/RAF/MEK, two signaling pathways, are urgent to improve the curative effect of kinase inhibitors and overcome acquired resistance.

METHODS/RESULTS

In the present study, 2-(2-aminopyrimidin-5-yl)-4-(morpholin-4-yl)-6-(N-cyclopropyl-N- (1-benzoylpiperidin-4-yl))triazines/pyrimidines were designed as PI3K and BRAF dual inhibitors. The synthesized 20 compounds exhibited potent antiproliferative effects in vitro against HCT116, A375, MCF-7, Colo205, A549 and LOVO cancer cell lines. The tested compounds A6, A7, A9 and A11 remarkably displayed inhibitory activities toward both PI3Kα and BRAF^V600E.

CONCLUSION

These results indicated that our design compounds can serve as potent PI3Kα and BRAF^V600E dual inhibitors and effective antiproliferative agents, which can be further optimized to discover more potent PI3Kα and BRAF^V600E dual inhibitors.

Understanding and treating solid tumor-related disseminated intravascular coagulation in the "era" of targeted cancer therapies

A systemic activation of blood coagulation is usually present in many clinical conditions including the infectious or inflammatory ones and malignant disease as well. Depending upon circumstances, patients suffering from acute decompensated disseminated intravascular coagulation may be managed by a medical oncologist and either an internist or a physician working in an emergency and/or intensive care unit. In some cases, for example, the indolent ones, the activation of coagulation might not be easily detected by routine laboratory tests and not lead to clinical manifestations. Such a chronically activated intravascular coagulation can progress toward an overt decompensated disseminated intravascular coagulation. Traditional therapy of decompensated disseminated intravascular coagulation is based on reversing the underlying triggering disease and providing patients with adequate supportive treatment. The dilemma for the oncologist is whether or not the trigger cause can be treated and amended with a specific antineoplastic treatment, without worsening the consumption of platelets and the risk of bleeding. In light of the availability of new targeted therapies, the main criteria that should drive the strategy against solid cancer-related disseminated intravascular coagulation will be discussed.

Super-enhancers define a proliferative PGC-1α-expressing melanoma subgroup sensitive to BET inhibition

Metabolic changes are linked to epigenetic reprogramming and play important roles in several tumor types. PGC-1α is a transcriptional coactivator controlling mitochondrial biogenesis and is linked to oxidative phosphorylation. We provide evidence that melanoma models with elevated PGC-1α levels are characteristic of the proliferative phenotype and are sensitive to bromodomain and extra-terminal domain (BET) inhibitor treatment. A super-enhancer region highly occupied by the BET family member BRD4 was identified for the PGC-1α gene. BET inhibitor treatment prevented this interaction, leading to a dramatic reduction of PGC-1α expression. Accordingly, BET inhibition diminished respiration and mitochondrial function in cells. In vivo, melanoma models with high PGC-1α expression strongly responded to BET inhibition by reduction of PGC-1α and impaired tumor growth. Altogether, our findings identify epigenetic regulatory elements that define a subset of melanomas with high sensitivity to BET inhibition, which opens up the opportunity to define melanoma patients most likely to respond to this treatment, depending on their tumor characteristics.

Anti-inflammatory effects of dabrafenib in vitro and in vivo

The screening of bioactive compound libraries can be an effective approach for repositioning FDA-approved drugs or discovering new treatments for human diseases (drug repositioning). Drug repositioning refers to the development of existing drugs for new indications. Dabrafenib (DAB) is a B-Raf inhibitor and initially used for the treatment of metastatic melanoma therapy. Here, we tested the possible use of DAB in the treatment of lipopolysaccharide (LPS)-mediated vascular inflammatory responses. The anti-inflammatory activities of DAB were determined by measuring permeability, neutrophils adhesion and migration, and activation of pro-inflammatory proteins in LPS-activated human umbilical vein endothelial cells (HUVECs) and mice. We found that DAB inhibited LPS-induced barrier disruption, expression of cell adhesion molecules (CAMs), and adhesion and transendothelial migration of neutrophils to human endothelial cells. DAB also suppressed LPS-induced hyperpermeability and leukocytes migration in vivo. Furthermore, DAB suppressed the production of tumor necrosis factor-α (TNF-α) or interleukin (IL)-6 and the activation of nuclear factor-κB (NF-κB) or extracellular regulated kinases (ERK) 1/2 by LPS. Moreover, treatment with DAB resulted in reduced LPS-induced lethal endotoxemia. These results suggest that DAB possesses anti-inflammatory functions by inhibiting hyperpermeability, expression of CAMs, and adhesion and migration of leukocytes, thereby endorsing its usefulness as a therapy for vascular inflammatory diseases.

Molecular analysis of BRAF V600E mutation in multiple nodules of pulmonary Langerhans cell histiocytosis

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare, smoking-related histiocytic disorder with variable clinical symptoms. Like in other non-pulmonary Langerhans cell proliferations, PLCH has recently been shown to harbour BRAF V600E mutations in a significant subset of cases, thus challenging the concept of PLCH being a reactive disorder. Here, we analysed 38 formalin-fixed and paraffin-embedded PLCH nodules of nine patients for BRAF mutation using two different molecular methods. Using pyrosequencing and allele-specific quantitative PCR (AS-PCR), BRAF V600E mutations were found in 16/38 (42%) and 31/37 (84%) nodules, respectively. Analysing different nodules of the same patients with pyrosequencing 3/6 patients showed a concordant BRAF mutation status. When allele-specific quantitative PCR was used, condordant results were found in 5/6 patients. Our findings clearly indicate that (a) the sensitivity of the method used is crucial in analysing BRAF mutation status, (b) AS-PCR is more sensitive in detecting BRAF V600E mutations than pyrosequencing,

Targeting melanoma with front-line therapy does not abrogate Nodal-expressing tumor cells

Metastatic melanoma is a highly aggressive skin cancer with a poor prognosis. It is the leading cause of skin cancer deaths with a median overall survival for advanced-stage metastatic disease of <6 months. Despite advances in the field with conventional and targeted therapies, the heterogeneity of melanoma poses the greatest ongoing challenge, ultimately leading to relapse and progression to a more drug-resistant tumor in most patients. Particularly noteworthy are recent findings, indicating that these therapies exert selective pressure on tumors resulting in the activation of pathways associated with cancer stem cells that are unresponsive to current therapy. Our previous studies have shown how Nodal, an embryonic morphogen of the transforming growth factor-beta superfamily, is one of these critical factors that is reactivated in aggressive melanoma and resistant to conventional chemotherapy, such as dacarbazine. In the current study, we sought to determine whether BRAF inhibitor (BRAFi) therapy targeted Nodal-expressing tumor cells in uniquely matched unresectable stage III and IV melanoma patient samples before and after therapy that preceded their eventual death due to disease. The results demonstrate that BRAFi treatment failed to affect Nodal levels in melanoma tissues. Accompanying experiments in soft agar and in nude mice showed the advantage of using combinatorial treatment with BRAFi plus anti-Nodal monoclonal antibody to suppress tumor growth and metastasis. These data provide a promising new approach using front-line therapy combined with targeting a cancer stem cell-associated molecule-producing a more efficacious response than monotherapy.

[The differential diagnosis of Erdheim-Chester disease and IgG4-related diseases]

The paper describes Russia's first diagnosed case of Erdheim--Chester disease (systemic histiocytosis) in a 65-year-old man who has been long treated for Ormond's disease (idiopathic retroperitoneal fibrosis). It also gives the data available in the literature on the pathogenetic components of these diseases and on the similarity of many clinical, laboratory, and morphological characteristics of these two immunoinflammatory diseases and covers the issues of their differential diagnosis. Invasive procedures with a careful morphological/immunomorphological examination of biopsy specimens obtained from affected tissues are shown to be necessary for accurate diagnosis.

Protein Kinase CK2α Maintains Extracellular Signal-regulated Kinase (ERK) Activity in a CK2α Kinase-independent Manner to Promote Resistance to Inhibitors of RAF and MEK but Not ERK in BRAF Mutant Melanoma

The protein kinase casein kinase 2 (CK2) is a pleiotropic and constitutively active kinase that plays crucial roles in cellular proliferation and survival. Overexpression of CK2, particularly the α catalytic subunit (CK2α, CSNK2A1), has been implicated in a wide variety of cancers and is associated with poorer survival and resistance to both conventional and targeted anticancer therapies. Here, we found that CK2α protein is elevated in melanoma cell lines compared with normal human melanocytes. We then tested the involvement of CK2α in drug resistance to Food and Drug Administration-approved single agent targeted therapies for melanoma. In BRAF mutant melanoma cells, ectopic CK2α decreased sensitivity to vemurafenib (BRAF inhibitor), dabrafenib (BRAF inhibitor), and trametinib (MEK inhibitor) by a mechanism distinct from that of mutant NRAS. Conversely, knockdown of CK2α sensitized cells to inhibitor treatment. CK2α-mediated RAF-MEK kinase inhibitor resistance was tightly linked to its maintenance of ERK phosphorylation. We found that CK2α post-translationally regulates the ERK-specific phosphatase dual specificity phosphatase 6 (DUSP6) in a kinase dependent-manner, decreasing its abundance. However, we unexpectedly showed, by using a kinase-inactive mutant of CK2α, that RAF-MEK inhibitor resistance did not rely on CK2α kinase catalytic function, and both wild-type and kinase-inactive CK2α maintained ERK phosphorylation upon inhibition of BRAF or MEK. That both wild-type and kinase-inactive CK2α bound equally well to the RAF-MEK-ERK scaffold kinase suppressor of Ras 1 (KSR1) suggested that CK2α increases KSR facilitation of ERK phosphorylation. Accordingly, CK2α did not cause resistance to direct inhibition of ERK by the ERK1/2-selective inhibitor SCH772984. Our findings support a kinase-independent scaffolding function of CK2α that promotes resistance to RAF- and MEK-targeted therapies.

The metabolic microenvironment of melanomas: Prognostic value of MCT1 and MCT4

BRAF mutations are known drivers of melanoma development and, recently, were also described as players in the Warburg effect, while this reprogramming of energy metabolism has been identified as a possible strategy for treating melanoma patients. Therefore, the aim of this work was to evaluate the expression and prognostic value of a panel of glycolytic metabolism-related proteins in a series of melanomas. The immunohistochemical expression of MCT1, MCT4, GLUT1, and CAIX was evaluated in 356 patients presenting melanoma and 20 patients presenting benign nevi. Samples included 20 benign nevi, 282 primary melanomas, 117 lymph node and 54 distant metastases samples. BRAF mutation was observed in 29/92 (31.5%) melanoma patients and 17/20 (85%) benign nevi samples. NRAS mutation was observed in 4/36 (11.1%) melanoma patients and 1/19 (5.3%) benign nevi samples. MCT4 and GLUT1 expression was significantly increased in metastatic samples, and MCT1, MCT4 and GLUT1 were significantly associated with poor prognostic variables. Importantly, MCT1 and MCT4 were associated with shorter overall survival. In conclusion, the present study brings new insights on metabolic aspects of melanoma, paving the way for the development of new-targeted therapies.

Radiotherapy with BRAF inhibitor therapy for melanoma: progress and possibilities

The introduction of small molecule BRAFV600 kinase inhibitors represents a milestone in the targeted therapy of patients with metastatic melanoma by a significant increase in therapeutic efficacy in terms of overall and progression-free survival compared with conventional chemotherapy. Beside BRAFV600 inhibitor treatment, radiotherapy is a further mainstay for the therapy of metastatic melanoma and thus a concomitant or sequential application of BRAFV600 inhibitors and radiotherapy is inevitable. Recent reports show a significant radiosensitization of the irradiated healthy tissue in patients with melanoma after the combination of radiotherapy and BRAFV600 inhibitors, evoking concern in clinical practice. We review interactions of BRAFV600 inhibitors and radiation with regard to antitumor effects and an increased radiotoxicity in the healthy tissue.

New developments in the management of advanced melanoma - role of pembrolizumab

Cancer immunotherapy is now recognized to be fundamental in modern oncology, because immune system recruitment may represent a powerful and innovative strategy in cancer therapy. Pembrolizumab, a highly selective humanized monoclonal antibody directly blocking the interaction between programmed cell death-1 expressed by tumor-associated T-cells and its ligand programmed cell death-L1 present on tumor and stromal cells, was recently approved by US Food and Drug Administration for the treatment of patients with unresectable or metastatic melanoma and disease progression upon ipilimumab and BRAF inhibitor. This review will focus on the clinical development and use of pembrolizumab in the clinical practice and in the management of advanced melanoma.

BRAF Mutation in Colorectal Cancer: An Update

Colorectal cancer (CRC) is still one of the deadliest cancer-related diseases. About 10% of CRC patients are characterized by a mutation in the B-Raf proto-oncogene serine/threonine kinase (BRAF) gene resulting in a valine-to-glutamate change at the residue 600 (V600E). This mutation is also present in more than 60% of melanoma patients. BRAF inhibitors were developed and found to improve patient survival; however, most patients at the end of the track ultimately develop resistance to these inhibitors. Melanoma patients benefit from the combination of BRAF inhibitors with mitogen/extracellular signal-regulated kinase (MEK) inhibitors, among others. Unfortunately, colorectal patients do not respond much efficiently, which suggests different resistance mechanisms between the two cancer types. This review aims at shedding light on recent discoveries that improve our understanding of the BRAF mutation biology in CRC.