Disulfiram/Cu Kills and Sensitizes BRAF-Mutant Thyroid Cancer Cells to BRAF Kinase Inhibitor by ROS-Dependently Relieving Feedback Activation of MAPK/ERK and PI3K/AKT Pathways.

BRAFV600E, the most common genetic alteration, has become a major therapeutic target in thyroid cancer. Vemurafenib (PLX4032), a specific inhibitor of BRAFV600E kinase, exhibits antitumor activity in patients with BRAFV600E-mutated thyroid cancer. However, the clinical benefit of PLX4032 is often limited by short-term response and acquired resistance via heterogeneous feedback mechanisms. Disulfiram (DSF), an alcohol-aversion drug, shows potent antitumor efficacy in a copper (Cu)-dependent way. However, its antitumor activity in thyroid cancer and its effect on cellular response to BRAF kinase inhibitors remain unclear. Antitumor effects of DSF/Cu on BRAFV600E-mutated thyroid cancer cells and its effect on the response of these cells to BRAF kinase inhibitor PLX4032 were systematically assessed by a series of in vitro and in vivo functional experiments. The molecular mechanism underlying the sensitizing effect of DSF/Cu on PLX4032 was explored by Western blot and flow cytometry assays. DSF/Cu exhibited stronger inhibitory effects on the proliferation and colony formation of BRAFV600E-mutated thyroid cancer cells than DSF treatment alone. Further studies revealed that DSF/Cu killed thyroid cancer cells by ROS-dependent suppression of MAPK/ERK and PI3K/AKT signaling pathways. Our data also showed that DSF/Cu strikingly increased the response of BRAFV600E-mutated thyroid cancer cells to PLX4032. Mechanistically, DSF/Cu sensitizes BRAF-mutant thyroid cancer cells to PLX4032 by inhibiting HER3 and AKT in an ROS-dependent way and subsequently relieving feedback activation of MAPK/ERK and PI3K/AKT pathways. This study not only implies potential clinical use of DSF/Cu in cancer therapy but also provides a new therapeutic strategy for BRAFV600E-mutated thyroid cancers.

In Silico Studies of Novel Vemurafenib Derivatives as BRAF Kinase Inhibitors.

BRAF inhibitors have improved the treatment of advanced or metastatic melanoma in patients that harbor a BRAFT1799A mutation. Because of new insights into the role of aberrant glycosylation in drug resistance, we designed and studied three novel vemurafenib derivatives possessing pentose-associated aliphatic ligands-methyl-, ethyl-, and isopropyl-ketopentose moieties-as potent BRAFV600E kinase inhibitors. The geometries of these derivatives were optimized using the density functional theory method. Molecular dynamic simulations were performed to find interactions between the ligands and BRAFV600E kinase. Virtual screening was performed to assess the fate of derivatives and their systemic toxicity, genotoxicity, and carcinogenicity. The computational mapping of the studied ligand-BRAFV600E complexes indicated that the central pyrrole and pyridine rings of derivatives were located within the hydrophobic ATP-binding site of the BRAFV600E protein kinase, while the pentose ring and alkyl chains were mainly included in hydrogen bonding interactions. The isopropyl-ketopentose derivative was found to bind the BRAFV600E oncoprotein with more favorable energy interaction than vemurafenib. ADME-TOX in silico studies showed that the derivatives possessed some desirable pharmacokinetic and toxicologic properties. The present results open a new avenue to study the carbohydrate derivatives of vemurafenib as potent BRAFV600E kinase inhibitors to treat melanoma.

Estimated sensitivity profiles of lung cancer specific uncommon BRAF mutants towards experimental and clinically approved kinase inhibitors.

Current experimental and clinical data are inadequate to conclusively predict the oncogenicity of uncommon BRAF mutants and their sensitivity towards kinase inhibitors. Therefore, the present study aims at estimating sensitivity profiles of uncommon lung cancer specific BRAF mutations towards clinically approved as well as experimental therapeutics based on computationally derived direct binding energies. Based on the data derived from cBioportal, BRAF mutants displayed significant mutual exclusivity with KRAS and EGFR mutants indicating them as potential drivers in lung cancer. Predicted sensitivity of BRAF-V600E conformed to published experimental and clinical data thus validating the usefulness of computational approach. The BRAF-V600K displayed higher sensitivity to most inhibitors as compared to that of the BRAF-V600E. All the uncommon mutants displayed higher sensitivity than both the wild type and BRAF-V600E towards PLX 8394 and LSN3074753. While V600K, G469R and N581S displayed favorable sensitivity profiles to most inhibitors, V600L/M, G466A/E/V and G469A/V displayed resistance profiles to a variable degree. Notably, molecular dynamic (MD) simulation revealed that increased number of interactions caused enhanced sensitivity of G469R and N581S towards sorafenib. RAF kinase inhibitors were further classified into two groups as per their selectivity (Group I: BRAF-V600E-selective and Group II: CRAF-selective) based on which potential mutation-wise combinations of RAF kinase inhibitors were proposed to overcome resistance. Based on computational inhibitor sensitivity profiles, appropriate treatment strategies may be devised to prevent or overcome secondary drug resistance in lung cancer patients with uncommon mutations.

New Potential Agents for Malignant Melanoma Treatment-Most Recent Studies 2020-2022.

Malignant melanoma (MM) is the most lethal skin cancer. Despite a 4% reduction in mortality over the past few years, an increasing number of new diagnosed cases appear each year. Long-term therapy and the development of resistance to the drugs used drive the search for more and more new agents with anti-melanoma activity. This review focuses on the most recent synthesized anti-melanoma agents from 2020-2022. For selected agents, apart from the analysis of biological activity, the structure-activity relationship (SAR) is also discussed. To the best of our knowledge, the following literature review delivers the latest achievements in the field of new anti-melanoma agents.

Investigation into the Use of Encorafenib to Develop Potential PROTACs Directed against BRAFV600E Protein.

BRAF is a serine/threonine kinase frequently mutated in human cancers. BRAFV600E mutated protein is targeted through the use of kinase inhibitors which are approved for the treatment of melanoma; however, their long-term efficacy is hampered by resistance mechanisms. The PROTAC-induced degradation of BRAFV600E has been proposed as an alternative strategy to avoid the onset of resistance. In this study, we designed a series of compounds where the BRAF kinase inhibitor encorafenib was conjugated to pomalidomide through different linkers. The synthesized compounds maintained their ability to inhibit the kinase activity of mutated BRAF with IC50 values in the 40-88 nM range. Selected compounds inhibited BRAFV600E signaling and cellular proliferation of A375 and Colo205 tumor cell lines. Compounds 10 and 11, the most active of the series, were not able to induce degradation of mutated BRAF. Docking and molecular dynamic studies, conducted in comparison with the efficient BRAF degrader P5B, suggest that a different orientation of the linker bearing the pomalidomide substructure, together with a decreased mobility of the solvent-exposed part of the conjugates, could explain this behavior.

Kidney toxicity of the BRAF-kinase inhibitor vemurafenib is driven by off-target ferrochelatase inhibition.

A multitude of disease and therapy related factors drive the frequent development of kidney disorders in cancer patients. Along with chemotherapy, the newer targeted therapeutics can also cause kidney dysfunction through on and off-target mechanisms. Interestingly, among the small molecule inhibitors approved for the treatment of cancers that harbor BRAF-kinase activating mutations, vemurafenib can trigger tubular damage and acute kidney injury. BRAF is a proto-oncogene involved in cell growth. To investigate the underlying mechanisms, we developed cell culture and mouse models of vemurafenib kidney toxicity. At clinically relevant concentrations vemurafenib induces cell-death in transformed and primary mouse and human kidney tubular epithelial cells. In mice, two weeks of daily vemurafenib treatment causes moderate acute kidney injury with histopathological characteristics of kidney tubular epithelial cells injury. Importantly, kidney tubular epithelial cell-specific BRAF gene deletion did not influence kidney function under normal conditions or alter the severity of vemurafenib-associated kidney impairment. Instead, we found that inhibition of ferrochelatase, an enzyme involved in heme biosynthesis contributes to vemurafenib kidney toxicity. Ferrochelatase overexpression protected kidney tubular epithelial cells and conversely ferrochelatase knockdown increased the sensitivity to vemurafenib-induced kidney toxicity. Thus, our studies suggest that vemurafenib-associated kidney tubular epithelial cell dysfunction and kidney toxicity is BRAF-independent and caused, in part, by off-target ferrochelatase inhibition.

Novel pyrrol-2(3H)-ones and pyridazin-3(2H)-ones carrying quinoline scaffold as anti-proliferative tubulin polymerization inhibitors.

A novel quinolinyl pyrrolone and quinolinyl pyridazinone derivatives has been synthesized and characterized using different spectroscopic and elemental analysis techniques. Most of the target compounds displayed promising antiproliferative activity; In general, the pyrrolone derivatives 4a-f exhibited higher antiproliferative activity than their corresponding pyridazinone. The pyrrolone 4f showed outstanding antiproliferative activity with moderate selectivity against CNS and renal cancer with selectivity ratio of 3.49 and 3.56, respectively. Compound 4e and 5d experienced tubulin polymerization inhibitory activity comparable to that of vincristine while 4c, 4e and 4d showed good BRAF kinase inhibition compared to Erlotinib. Docking of compound 4e into colchicine binding site and biological assay results revealed that these compounds act mainly through tubulin polymerization inhibitory mechanism and can exhibit pre G1 apoptosis and cell cycle arrest at G2/M phase.

BRAF--a new player in hematological neoplasms.

BRAF oncogenic kinase has become a target for specific therapy in oncology. Genetic characterization of a predominant V600E mutation in melanoma, thyroid cancer, and other tumors became a focus for developing specific inhibitors, such as vemurafenib or dabrafenib. Our knowledge regarding the role of mutated BRAF in hematological malignancies has grown quickly as a result of new genetic techniques such as next-generation sequencing. This review summarizes current knowledge regarding the role of BRAF in lymphoid and myeloid neoplasms, with a focus on hairy-cell leukemia, Langerhans cell histiocytosis, and Erdheim-Chester disease.

Revisiting the Role of B-RAF Kinase as a Therapeutic Target in Melanoma.

Malignant melanoma is the rarest but most aggressive and deadly skin cancer. Melanoma is the result of a malignant transformation of melanocytes, which leads to their uncontrolled proliferation. Mutations in the mitogen-activated protein kinase (MAPK) pathway, which are crucial for the control of cellular processes, such as apoptosis, division, growth, differentiation, and migration, are one of its most common causes. BRAF kinase, as one of the known targets of this pathway, has been known for many years as a prominent molecular target in melanoma therapy, and the following mini-review outlines the state-of-the-art knowledge regarding its structure, mutations and mechanisms.

BRAF testing modalities in histiocytic disorders: Comparative analysis and proposed testing algorithm.

OBJECTIVES: Understanding of histiocytic disorders has been revolutionized by demonstration of mitogen-activated protein kinase (MAPK) pathway mutations, most commonly BRAFV600E. The optimal testing strategy to assess BRAFV600E is unknown. We aimed to compare performance of testing modalities, to propose a framework for evaluation of BRAFV600E mutation status in histiocytic disorders. METHODS: We retrospectively reviewed patients with histiocytic disorders and BRAF mutation testing on a lesional tissue specimen. RESULTS: In 120 patients, BRAF assessment included immunohistochemistry (IHC) in 97 (80.2%), polymerase chain reaction (PCR) in 35 (28.9%), and next-generation sequencing (NGS) in 62 (51.2%). Forty-five underwent both NGS and IHC. With NGS as the gold standard, the sensitivity and specificity of IHC were 82.4% and 96.4%. Three false negatives were observed in biopsy specimens with low BRAFV600E variant allele frequency or decalcified tissue. One false-positive IHC was observed in a lung biopsy specimen, likely due to antibody cross-reactivity with respiratory cilia. Among 14 with successful NGS and PCR, a single discordance was observed. Two PCR-to-IHC discrepancies were observed, including one other false-positive IHC. CONCLUSIONS: Immunohistochemistry was highly specific for detection of BRAFV600E. Main caveats were false negatives and lack of detection of non-BRAFV600E mutations. We propose the use of IHC as initial screening in general practice with reflex molecular testing if negative.

Pin1 inhibitor API-1 sensitizes BRAF-mutant thyroid cancers to BRAF inhibitors by attenuating HER3-mediated feedback activation of MAPK/ERK and PI3K/AKT pathways.

BRAFV600E mutation is one of the most therapeutic targets in thyroid cancers. However, its specific inhibitors have shown little clinical benefit because they can reactivate the MAPK/ERK and PI3K/AKT pathways by feedback upregulating the transcription of HER3. Peptidyl-prolyl cis/trans isomerase Pin1 has been proven to be closely associated with tumor progression. Here, we aimed to determine antitumor activity of Pin1 inhibitor API-1 in thyroid cancer and its effect on cellular response to BRAF inhibitors. The results showed that API-1 exhibited strong antitumor activity against thyroid cancer. Meanwhile, it improved the response of BRAF-mutant thyroid cancer cells to BRAF inhibitor PLX4032 and there was a synergistic effect between them. Specially, a combination therapy of API-1 and PLX4032 significantly inhibited cell proliferation, colony formation, and the growth of xenograft tumors as well as induced cell apoptosis in BRAF-mutant thyroid cancer cells compared with API-1 or PLX4032 monotherapy. Similar results were also observed in transgenic mice with BrafV600E-driven thyroid cancer. Mechanistically, API-1 enhanced XPO5 ability to export pre-microRNA 20a (pre-miR-20a) from the nucleus to cytoplasm, thereby promoting the maturation of miR-20a-5p. Further studies showed that miR-20a-5p specifically targeted and down-regulated HER3, thereby blocking the reactivation of MAPK/ERK and PI3K/AKT signaling pathways caused by PLX4032. These results, taken together, demonstrate that Pin1 inhibitor API-1 significantly improves the sensitivity of BRAF-mutant thyroid cancer cells to PLX4032. Thus, this study not only determines the potential antitumor activity of Pin1 inhibitor API-1 in thyroid cancer but also offers an alternative therapeutic strategy for BRAF-mutant thyroid cancers by a combination of Pin1 inhibitor and BRAF kinase inhibitor.

Systematic review of randomised clinical trials and observational studies for patients with RAS wild-type or BRAFV600E-mutant metastatic and/or unresectable colorectal cancer.

Approximately 8-10% of metastatic colorectal cancer (mCRC) tumours harbour BRAFV600E mutations. Eleven randomised controlled trials (RCTs) and 24 non-RCTs were identified. Seven studies evaluated BRAF inhibitors. Single-agent BRAF inhibitors had minimal efficacy, whereas BRAF inhibitor plus anti-EGFR therapy improved outcomes. In BEACON CRC, overall survival (OS) was significantly longer for patients receiving encorafenib plus cetuximab ± binimetinib when compared with irinotecan/FOLFIRI plus cetuximab as second- and third-line therapy. Seven prospective non-RCTs reported worse OS and progression-free survival (PFS) for patients with BRAFV600E-mutant vs BRAF wild-type mCRC. Eight RCTs reported that PFS and OS were generally shorter for patients with BRAFV600E-mutant mCRC vs those with KRAS or RAS wild-type mCRC. Patients with BRAFV600E-mutant mCRC have worse outcomes with conventional therapy vs patients with BRAF wild-type tumours. BRAF inhibitors in conjunction with anti-EGFR therapy improves outcomes for patients with BRAFV600E-mutant mCRC vs conventional therapy or a BRAF inhibitor alone.

Prediction of BRAF V600E variant from cancer gene expression data.

Background: BRAF inhibitors have been approved for the treatment of melanoma, non-small cell lung cancer, and colon cancer. Real-time polymerase chain reaction or next-generation sequencing were clinically used for BRAF variant detection to select who responds to BRAF inhibitors. The prediction of BRAF variants using gene expression data might be an alternative test when the direct variant sequencing test is not feasible. In this study, we built a prediction model to detect BRAF V600 variants with mRNA gene expression data in various cancer types. Methods: We adopted a penalized logistic regression for the BRAF V600E variants prediction model. Ten times bootstrap resampling was done with a combined target variable and cancer type stratification. Data preprocessing included knnimputation for missing value imputation, YeoJohnson transformation for skewness correction, center, and scale for standardization, synthetic minority over-sampling technique for class imbalance. Hyperparameter optimization with a grid search was undertaken for model selection in terms of area under the precision-recall. Results: The area under the curve of the receiver operating characteristic curve on the test set was 0.98 in thyroid carcinoma, 0.90 in colon adenocarcinoma, and 0.85 in cutaneous melanoma. The area under the precision-recall of the test set was 0.98 in thyroid carcinoma, 0.71 in colon adenocarcinoma, and 0.65 in cutaneous melanoma. Conclusions: Our penalized logistic regression model can predict BRAF V600E variants with good performance in thyroid carcinoma, cutaneous melanoma, and colon adenocarcinoma.

Dual SMO/BRAF Inhibition by Flavonolignans from Silybum marianum †.

Silymarin is the standardized extract from the fruits of Silybum marianum (L.) Gaertn., a well-known hepatoprotectant and antioxidant. Recently, bioactive compounds of silymarin, i.e., silybins and their 2,3-dehydro derivatives, have been shown to exert anticancer activities, yet with unclear mechanisms. This study combines in silico and in vitro methods to reveal the potential interactions of optically pure silybins and dehydrosilybins with novel protein targets. The shape and chemical similarity with approved drugs were evaluated in silico, and the potential for interaction with the Hedgehog pathway receptor Smoothened (SMO) and BRAF kinase was confirmed by molecular docking. In vitro studies on SMO and BRAF V600E kinase activity and in BRAF V600E A-375 human melanoma cell lines were further performed to examine their effects on these proteins and cancer cell lines and to corroborate computational predictions. Our in silico results direct to new potential targets of silymarin constituents as dual inhibitors of BRAF and SMO, two major targets in anticancer therapy. The experimental studies confirm that BRAF kinase and SMO may be involved in mechanisms of anticancer activities, demonstrating dose-dependent profiles, with dehydrosilybins showing stronger effects than silybins. The results of this work outline the dual SMO/BRAF effect of flavonolignans from Silybum marianum with potential clinical significance. Our approach can be applied to other natural products to reveal their potential targets and mechanism of action.

Chemotherapeutic effects of MEK kinase inhibitor and BRAF kinase inhibitor on KRAS-mutated human colon cancer cell lines with different microsatellite instability.

We analyzed responsiveness of KRAS-mutated CRC cell lines with distinctive MSI status against mitogen-activated protein kinase (MEK) inhibitor (selumetinib; AZD) and/or B-raf proto-oncogene (BRAF) kinase inhibitor (vemurafenib; PLX). The viability of MSI-high (MSI-H) KRAS-mutated LS174T cells treated with AZD or PLX was 24.5 ± 0.9% or 71.4 ± 3.6%, respectively, and the viability of microsatellite stable (MSS) KRAS-mutated SW480 cells for AZD or PLX was 57.4 ± 3.1% or 43.1 ± 1.8%, respectively. These observations imply that the therapeutic efficacy of MEK kinase inhibitors or BRAF kinase inhibitors against KRAS-mutated colon cancer cells may differ between MSI-H and MSS. However, a combination of both inhibitors synergistically inhibits the proliferation of KRAS-mutated colon cancer cells regardless of MSI status. The underlying synergistic cytotoxic efficacy of AZD/PLX combination on KRAS-mutated colon cancer cells with different MSI status was further substantiated by markedly decreased phosphorylation of ERK in both LS74T and SW480 cell lines upon AZD and PLX treatment. Based on these collective data, we propose that MSI status should be considered when MEK kinase inhibitor or BRAF kinase inhibitor is treated for KRAS-mutated colon cancer, and that combination of both inhibitors synergistically inhibit proliferation of KRAS-mutated colon cancer cells independent of MSI status.

An alternative pathway for cellular protection in BRAF inhibitor resistance in aggressive melanoma type skin cancer.

Oncogenic alterations in the BRAF gene are identified in an estimate of 50% of melanomas and cause melanoma development. BRAF kinase inhibitors (BRAFi), including vemurafenib and dabrafenib, were discovered and used in the clinical treatment of BRAF-mutant metastatic melanoma. Though, BRAFi's therapeutic advantages are short term and short-lived associated with drug resistance. Although a few pathways of developed BRAFi resistance have also been established, in approximately 40% of melanomas, the cause for inherited resistance remains unclear. Recognizing a new process of developed BRAFi resistance might provide new possibilities to successfully treat BRAF mutant melanoma. In this study, we are exploring the compensatory alternative pathway followed by BRAFi/MEKi treated resistant cell for maintaining the long-term integrity and survival.

High iodine effects on the proliferation, apoptosis, and migration of papillary thyroid carcinoma cells as a result of autophagy induced by BRAF kinase.

Papillary thyroid carcinoma (PTC) is a common endocrine tumor. This study found that different iodine concentrations affected the proliferation, apoptosis, and migration of PTC. For this study, we collected clinical information from PTC patients and monitored the levels of urinary iodine, LC3-II, and caspase-3 in cancer tissue, and BRAF kinase in peripheral blood from PTC patients. We also monitored the proliferation, apoptosis and migration ability of human papillary-thyroid carcinoma (BCPAP) cells at different iodine concentrations and their association with changes in autophagy and BRAF kinase activity of BCPAP cells at high iodine levels (10-3 mol/l). We found that the proportion of tumor diameters ≥ 1 cm in the iodine excess group were lower than that in the iodine non-excess group. The proportion of PTC patients with infiltration in the iodine excess group was higher than that in the iodine non-excess group. Levels of the autophagy-related protein LC3-II and the apoptosis-related protein caspase-3 in cancer tissues, and activity of BRAF kinase in peripheral blood, were positively correlated with urinary iodine concentrations from PTC patients. At high iodine levels, the proliferation rate decreased, and apoptosis percentage and migration rates increased compared with the no-iodine group. At high iodine levels, the frequencies of autophagosomes (Aph) and autophagosome-lysosomes (Apl) in BCPAP cells increased significantly, and activities of LC3-II and BRAF kinase increased, respectively. The activity of LC3-II decreased when BRAF kinase was inhibited. The activity of LC3-II and the proliferation and migration rates of BCPAP cells decreased, and the apoptosis percentage increased when autophagy was inhibited at high iodine concentrations. Our results demonstrated that, in the presence of excessive iodine, the mean tumor size of PTC patients was smaller and easier to invade than tumors in patients not supplied with excessive iodine. The levels of autophagy and apoptosis in PTC cancer tissues, and activities of BRAF kinase in peripheral blood increased with increasing urinary iodine concentrations. High iodine levels inhibited cell proliferation and promoted apoptosis and migration of PTC cells. Autophagy induced by BRAF kinase in PTC cells was involved in anti-apoptosis, and promoted proliferation and migration at high iodine concentrations. This study provides a rationale for iodine supplementation in PTC patients.

Molecular insight into mutation-induced conformational change in metastasic bowel cancer BRAF kinase domain and its implications for selective inhibitor design.

Oncogenic BRAF V600E mutation confers constitutive activation for the kinase and is closely related to the pathogenesis of metastasic bowel cancer (MBC). Here, the V600E-induced conformational change in MBC BRAF kinase domain is characterized systematically at structural, energetic and dynamic levels. The mutation is observed to cause a conformational conversion of the kinase's activation loop from DFG-out to DFG-in, thus activating the kinase. Electrostatic force is primarily responsible for the conformational conversion and stabilization of DFG-in associated with the mutation. Molecular docking calculations are employed to analyze the binding mode difference of mutant-selective inhibitors between the DFG-out and DFG-in conformations of BRAF kinase. It is revealed that the mutation can reshape inhibitor selectivity profile by altering kinase loop conformation. Several compounds are determined to have a high or moderate selectivity for mutant over wild-type kinase. The selectivity is primarily originated from hydrogen bond interactions of inhibitor ligands with mutant rather than wild type due to the conformational difference in kinase domain.

Chemotherapeutic drug selectivity between wild-type and mutant BRaf kinases in colon cancer.

Oncogenic BRaf V600E mutation is involved in the development, invasion and metastasis of colon cancer. Selective inhibition of BRafV600E mutant has been recognized as a therapeutic strategy for the cancer. Here, we carried out atomistic molecular dynamics (MD) simulations to characterize the structural basis, energetic property, and dynamics behavior of conformational change in BRaf activation loop upon the mutation. It is found that V600E mutation destabilizes inactive DFG-out conformation of activation loop and promotes its conversion to the active DFG-in conformation, thus conferring constitutive activity for BRaf kinase. A further analysis revealed that the conformational change is induced by electrostatic effect of the negatively charged mutant residue Glu600, which can form a potent salt bridge with the positively charged residue Lys570; this is naturally consistent with phosphorylation of activation loop to activate the kinase. Both of them introduce a negative charge to activation loop and, consequently, the DFG-out is destabilized and conversed to DFG-in. Energetic analysis unraveled that small-molecule kinase inhibitor PLX4720 has a similar selectivity profile for mutant over wild-type kinases and for phosphorylated and dephosphorylated kinases. This can be substantiated in part by in vitro kinase assay that the inhibitor exhibits 12.6 and 10.4-fold higher potencies against mutant than wild type and against phosphorylated than dephosphorylated, respectively. It is suggested that the activation loop conformation, but neither V600E mutation nor phosphorylation, directly determines inhibitor affinity; the mutation and phosphorylation can only indirectly influence inhibitor binding via regulation of activation loop conformation. Graphical Abstract Chemotherapeutic drug selectivity between wild-type and mutant BRaf kinases in colon cancerᅟ.

BRAF V600E mutation and BRAF kinase inhibitors in conjunction with stereotactic radiosurgery for intracranial melanoma metastases.

OBJECTIVE Recent advancements in molecular biology have identified the BRAF mutation as a common mutation in melanoma. The wide use of BRAF kinase inhibitor ( BRAFi) in patients with metastatic melanoma has been established. The objective of this study was to examine the impact of BRAF mutation status and use of BRAFi in conjunction with stereotactic radiosurgery (SRS). METHODS This was a single-center retrospective study. Patient's charts and electronic records were reviewed for date of diagnosis of primary malignancy, BRAF mutation status, chemotherapies used, date of the diagnosis of CNS metastases, date of SRS, survival, local tumor control after SRS, and adverse events. Patients were divided into 3 groups: Group A, those with mutant BRAF without BRAFi treatment (13 patients); Group B, those with mutant BRAF with BRAFi treatment (17 patients); and Group C, those with wild-type BRAF (35 patients). Within a cohort of 65 patients with the known BRAF mutation status and treated with SRS between 2010 and 2014, 436 individual brain metastases (BMs) were identified. Kaplan-Meier methodology was then used to compare survival based on each binary parameter. RESULTS Median survival times after the diagnosis of melanoma BM and after SRS were favorable in patients with a BRAF mutation and treated with SRS in conjunction with BRAFi (Group B) compared with the patients with wild-type BRAF (Group C, 23 vs 8 months and 13 vs 5 months, respectively; p < 0.01, log-rank test). SRS provided a local tumor control rate of 89.4% in the entire cohort of patients. Furthermore, the local control rate was improved in the patients treated with SRS in conjunction with BRAFi (Group B) compared with patients with wild-type (Group C) or with BRAF mutation but no BRAFi (Group A) as an adjunct treatment for BMs. CONCLUSIONS BRAF mutation status appears to play an important role as a potent prognostic factor in patients harboring melanoma BM. BRAFi in conjunction with SRS may benefit this group of patients in terms of BM survival and SRS with an acceptable safety profile.