The ERK5 pathway in BRAFV600E melanoma cells plays a role in development of acquired resistance to dabrafenib but not vemurafenib.

Malignant melanoma, an aggressive skin cancer with a poor prognosis, frequently features BRAFV600E mutation resulting in activation of the MAPK pathway and melanocyte proliferation and survival. BRAFV600E inhibitors like vemurafenib and dabrafenib have enhanced patient survival, yet drug resistance remains a significant challenge. We investigated the role of the ERK5 pathway in BRAFV600E melanoma cells and cells with acquired resistance to PLX4720 (vemurafenib) and dabrafenib. In BRAFV600E melanoma, ERK5 inhibition minimally affected viability compared to ERK1/2 inhibition. In vemurafenib-resistant cells, ERK5 inhibition alone didn't impact viability or restore drug sensitivity to vemurafenib. However, in dabrafenib-resistant cells, ERK5 inhibition reduced viability and enhanced the anti-proliferative effect of MEK1/2 inhibition. Targeting the ERK5 pathway may represent a therapeutic opportunity in dabrafenib-resistant melanoma.

Polyamine and EIF5A hypusination downstream of c-Myc confers targeted therapy resistance in BRAF mutant melanoma.

BACKGROUND: BRAF inhibitors are widely employed in the treatment of melanoma with the BRAF V600E mutation. However, the development of resistance compromises their therapeutic efficacy. Diverse genomic and transcriptomic alterations are found in BRAF inhibitor resistant melanoma, posing a pressing need for convergent, druggable target that reverse therapy resistant tumor with different resistance mechanisms. METHODS: CRISPR-Cas9 screens were performed to identify novel target gene whose inhibition selectively targets A375VR, a BRAF V600E mutant cell line with acquired resistance to vemurafenib. Various in vitro and in vivo assays, including cell competition assay, water soluble tetrazolium (WST) assay, live-dead assay and xenograft assay were performed to confirm synergistic cell death. Liquid Chromatography-Mass Spectrometry analyses quantified polyamine biosynthesis and changes in proteome in vemurafenib resistant melanoma. EIF5A hypusination dependent protein translation and subsequent changes in mitochondrial biogenesis and activity were assayed by O-propargyl-puromycin labeling assay, mitotracker, mitoSOX labeling and seahorse assay. Bioinformatics analyses were used to identify the association of polyamine biosynthesis with BRAF inhibitor resistance and poor prognosis in melanoma patient cohorts. RESULTS: We elucidate the role of polyamine biosynthesis and its regulatory mechanisms in promoting BRAF inhibitor resistance. Leveraging CRISPR-Cas9 screens, we identify AMD1 (S-adenosylmethionine decarboxylase 1), a critical enzyme for polyamine biosynthesis, as a druggable target whose inhibition reduces vemurafenib resistance. Metabolomic and proteomic analyses reveal that polyamine biosynthesis is upregulated in vemurafenib-resistant cancer, resulting in enhanced EIF5A hypusination, translation of mitochondrial proteins and oxidative phosphorylation. We also identify that sustained c-Myc levels in vemurafenib-resistant cancer are responsible for elevated polyamine biosynthesis. Inhibition of polyamine biosynthesis or c-Myc reversed vemurafenib resistance both in vitro cell line models and in vivo in a xenograft model. Polyamine biosynthesis signature is associated with poor prognosis and shorter progression free survival after BRAF/MAPK inhibitor treatment in melanoma cohorts, highlighting the clinical relevance of our findings. CONCLUSIONS: Our findings delineate the molecular mechanisms involving polyamine-EIF5A hypusination-mitochondrial respiration pathway conferring BRAF inhibitor resistance in melanoma. These targets will serve as effective therapeutic targets that can maximize the therapeutic efficacy of existing BRAF inhibitors.

VIC Regimen (Vemurafenib/Irinotecan/Cetuximab) Versus Bevacizumab Plus Chemotherapy as First-Line Treatment for BRAF V600E-Mutated Unresectable or Metastatic Colorectal Cancer in Asian Patients: A Prospective Cohort Study.

BACKGROUND: Colorectal cancers (CRC) with BRAF V600E mutation exhibit limited chemotherapy response and a poor prognosis. Safety and efficacy of the VIC (Vemurafenib/Irinotecan/Cetuximab) regimen in the first-line setting for patients with BRAF V600E-mutated CRC remain undetermined. METHODS: In the prospective cohort study, the untreated, BRAF V600E-mutated, unresectable or metastatic CRC patients were enrolled. The VIC regimen and bevacizumab plus chemotherapy were compared in the first-line setting. The objective response rate (ORR), disease control rate (DCR), conversion resection rate, progression-free survival (PFS), and overall survival (OS) were evaluated. RESULTS: In the intent-to-treat analysis, 38 patients received VIC regimen and 40 received bevacizumab plus chemotherapy. The ORR and DCR in the VIC group were significantly higher than in the bevacizumab-therapy group (ORR: 63.2% vs. 37.5%, P = .025; DCR: 94.7% vs. 75.0%, P = .019). The VIC regimen significantly outperformed bevacizumab plus chemotherapy in both PFS (11.9 vs. 7.7 months; hazard ratio [HR] = 0.51, 95% CI, 0.30-0.87; P = .010) and OS (25.3 vs. 14.6 months; HR = 0.43, 95% CI, 0.22-0.82; P = .011). In the VIC group, the conversion resection rate for liver metastases was 34.8% (8 of 23 patients), and for unresectable local CRC it was 54.5% (6 of 11 patients). The adverse events rates of Grade 3 to 4 were 34.2% and 32.5% for the VIC regimen and bevacizumab plus chemotherapy respectively. CONCLUSIONS: Among Asian patients with BRAF V600E-mutated CRC, the VIC regimen showed favorable outcomes compared to bevacizumab plus chemotherapy in terms of tumor response and oncological survival, with a tolerable and manageable toxicity profile in the first-line setting.

Phase II study of vemurafenib in children and young adults with tumors harboring BRAF V600 mutations: NCI-COG pediatric MATCH trial (APEC1621) Arm G.

BACKGROUND: This is a phase II subprotocol of the NCI-COG Pediatric MATCH study evaluating vemurafenib, a selective oral inhibitor of BRAF V600 mutated kinase, in patients with relapsed or refractory solid tumors harboring BRAF V600 mutations. METHODS: Patients received vemurafenib at 550 mg/m2 (maximum 960 mg/dose) orally twice daily for 28-day cycles until progression or intolerable toxicity. The primary aim was to determine the objective response rate and secondary objectives included estimating progression-free survival and assessing the tolerability of vemurafenib. RESULTS: Twenty-two patients matched to the subprotocol and 4 patients (18%) enrolled. Primary reasons for non-enrollment were ineligibility due to exclusions of low-grade glioma (nâ=â7) and prior BRAF inhibitor therapy (nâ=â7). Enrolled diagnoses were one each of histiocytosis, ameloblastoma, Ewing sarcoma, and high-grade glioma, all with BRAF V600E mutations. Treatment was overall tolerable with mostly expected grade 1/2 adverse events (AE). Grade 3 or 4 AE on treatment were acute kidney injury, hyperglycemia, and maculopapular rash. One patient came off therapy due to AE. One patient (glioma) had an objective partial response and remained on protocol therapy for 15 cycles. CONCLUSION: There was a low accrual rate on this MATCH subprotocol, with only 18% of those who matched with BRAFV600 mutations enrolling, resulting in early termination, and limiting study results (ClinicalTrials.gov Identifier: NCT03220035).

Tunlametinib (HL-085) plus vemurafenib in patients with advanced BRAF V600-mutant solid tumors: an open-label, single-arm, multicenter, phase I study.

BACKGROUND: Tunlametinib (HL-085) is a novel, highly selective MEK inhibitor with substantial clinical activities in patients with NRAS-mutant melanoma. This phase I study evaluated the safety and preliminary efficacy of tunlametinib plus vemurafenib in patients with advanced BRAF V600-mutant solid tumors. METHODS: Patients with confirmed advanced BRAF V600-mutant solid tumors who had progressed on or shown intolerance or no available standard therapies were enrolled and received tunlametinib plus vemurafenib. This study consisted of a dose-escalation phase and a dose-expansion phase. Primary end points of this study were safety, the recommended phase II dose (RP2D), and preliminary efficacy. RESULTS: From August 17, 2018 to April 19, 2022, 72 patients were enrolled. No dose-limiting toxicities occurred, and the maximum tolerated dose was not reached. The RP2D for BRAF V600-mutant non-small cell lung cancer (NSCLC) patients was tunlametinib 9 mg plus vemurafenib 720 mg, twice daily (BID, bis in die). Until the data cut-off date of December 15, 2023, of 33 NSCLC patients with evaluable disease, the objective response rate (ORR) was 60.6% (20/33; 95% confidence interval [CI], 42.1-77.1), the median progression free survival (PFS) was 10.5 months (95%CI, 5.6-14.5) and median duration of response (DoR) was 11.3 months (95%CI, 6.8-NE). At the RP2D, ORR was 60.0% (9/15; 95% CI, 32.3-83.7), the median PFS was 10.5 months (95%CI, 5.6 -NE) and median DoR was 11.3 months (95%CI, 3.9-NE). Of 24 colorectal cancer patients with evaluable disease, the ORR was 25.0% (6/24; 95% CI, 5.6-NE). All 72 patients had treatment-related adverse events (TRAEs), and the most common grade 3-4 TRAEs were anemia (n = 13, 18.1%) and blood creatine phosphokinase increased (n = 10, 13.9%). Tunlametinib was absorbed rapidly with Tmax of 0.5-1 h. Vemurafeinib did not influence the system exposure of tunlametinib and vice versa, indicating no drug-drug interaction for this combination. CONCLUSIONS: Tunlametinib (HL-085) plus vemurafenib had a favorable safety profile and showed promising antitumor activity in patients with BRAF V600-mutant solid tumors. The RP2D for NSCLC was tunlametinib 9 mg BID plus vemurafeinib 720 mg BID. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03781219.

Extracellular vesicles promote migration despite BRAF inhibitor treatment in malignant melanoma cells.

Extracellular vesicles (EVs) constitute a vital component of intercellular communication, exerting significant influence on metastasis formation and drug resistance mechanisms. Malignant melanoma (MM) is one of the deadliest forms of skin cancers, because of its high metastatic potential and often acquired resistance to oncotherapies. The prevalence of BRAF mutations in MM underscores the importance of BRAF-targeted therapies, such as vemurafenib and dabrafenib, alone or in combination with the MEK inhibitor, trametinib. This study aimed to elucidate the involvement of EVs in MM progression and ascertain whether EV-mediated metastasis promotion persists during single agent BRAF (vemurafenib, dabrafenib), or MEK (trametinib) and combined BRAF/MEK (dabrafenib/trametinib) inhibition.Using five pairs of syngeneic melanoma cell lines, we assessed the impact of EVs - isolated from their respective supernatants - on melanoma cell proliferation and migration. Cell viability and spheroid growth assays were employed to evaluate proliferation, while migration was analyzed through mean squared displacement (MSD) and total traveled distance (TTD) measurements derived from video microscopy and single-cell tracking.Our results indicate that while EV treatments had remarkable promoting effect on cell migration, they exerted only a modest effect on cell proliferation and spheroid growth. Notably, EVs demonstrated the ability to mitigate the inhibitory effects of BRAF inhibitors, albeit they were ineffective against a MEK inhibitor and the combination of BRAF/MEK inhibitors. In summary, our findings contribute to the understanding of the intricate role played by EVs in tumor progression, metastasis, and drug resistance in MM.

Advances in Understanding and Management of Erdheim-Chester Disease.

Erdheim Chester Disease (ECD) is a rare histiocytic disorder marked by infiltration of organs with CD68+ histiocytes. ECD stems from mutations of BRAF and MAP2K1 in hematopoietic stem and progenitor cells (HSPCs), which further differentiate into monocytes and histiocytes. Histopathology reveals lipid-containing histiocytes, which test positive for CD68 and CD133 in immunohistochemistry. Signs and symptoms vary and depend on the organ/s of manifestation. Definitive radiological results associated with ECD include hairy kidney, coated aorta, and cardiac pseudotumor. Treatment options primarily include anti-cytokine therapy and inhibitors of BRAF and MEK signaling.

Development and in-depth characterization of BRAFi-resistant melanoma cell lines in vitro and in vivo.

Regardless of the clinical response and improved patient survival observed following treatment with BRAFi like Vemurafenib (Vem), rapid development of resistance still remains as a major obstacle in melanoma therapy. In this context, we developed and characterized two acquired Vem-resistant melanoma cell lines, A375V and SK-MEL-28V, and an intrinsically Vem-resistant cell line, RPMI-7951. Altered morphology and growth rate of the resistant cell lines displayed spindle-shaped cells with filopodia formation and enhanced proliferation rate as compared to parental cells. Further in vitro characterization in 2D models confirmed the emergence of a resistant phenotype in melanoma cells. To mimic the in vivo tumor microenvironment, spheroids were developed for both parental and resistant cell lines to recognize materialization of invadopodia structures demonstrating elevated invasiveness and proliferation of resistant cells-based spheroids, especially A375V. Importantly, we validated A375V cell line in vivo to prove its tumorigenicity and drug resistance in tumor xenograft model. Taken together, our established clinically relevant Vem-resistant tumor model could be beneficial to elucidate drug resistance mechanisms, screen and identify novel anticancer therapies to overcome BRAFi resistance in melanoma.

Single agent vemurafenib or rituximab-vemurafenib combination for the treatment of relapsed/refractory hairy cell leukemia, a multicenter experience.

BACKGROUND: Hairy cell leukemia (HCL) is a rare mature B-cell malignancy that is primarily treated with purine analogues. However, relapse remains a significant challenge, prompting the search for alternative therapies. The BRAF V600E mutation prevalent in HCL patients provides a target for treatment with vemurafenib. PATIENTS AND METHODS: This multicenter retrospective study included nine patients with relapsed/refractory (R/R) HCL from six different centers. Patient data included demographics, prior treatments, clinical outcomes, and adverse events. RESULTS: Patients received different treatment regimens between centers, including vemurafenib alone or in combination with rituximab. Despite the differences in protocols, all patients achieved at least a partial response, with seven patients achieving a complete response. Adverse events were generally mild with manageable side effects. The absence of myelotoxic effects and manageable side effects make BRAF inhibitors attractive, especially for patients ineligible for purine analogues or those with severe neutropenia. CONCLUSION: Single agent vemurafenib or in combination with rituximab appears to be a promising therapeutic option for R/R HCL. Further research is needed to establish standardized treatment protocols and to investigate long-term outcomes.

Extra-nuclear TERT counteracts oxidative stress and promotes progression in papillary thyroid carcinoma.

The reactivation of TERT is associated with poor outcome in papillary thyroid cancer (PTC). Extra-telomeric functions of TERT were reported, with a protective role against oxidative stress (OS). The aim of the present study was to explore the extra-nuclear TERT localization in PTC and its role in cancer progression. TERT nuclear export under OS were analyzed in K1 PTC cell line. We investigated the role of different TERT localizations using specific TERT constructs that limit its localization to the nucleus or to the mitochondria. The effect of SRC kinase inhibitor PP2, which reduces TERT nuclear export, was investigated as well. Moreover, TERT localization was analyzed in 39 PTC tissues and correlated with the genetic profile and the level of OS, DNA damage and apoptosis in the tumors and with the clinical characteristics of the patients. We demonstrated that TERT is exported from the nucleus in response to OS induced either from H2O2 or the BRAF inhibitor PLX4720. We proved that extra-nuclear TERT reduces mitochondrial OS and induces mitochondrial fragmentation. Moreover, limiting mitochondrial TERT localization reduced proliferation, migration, AKT phosphorylation and glycolysis and increased DNA damage and p21 expression. Finally, in PTC tissues the fraction of mitochondrial/nuclear TERT resulted inversely correlated with OS and p21 expression and associated with tumor persistence. In conclusion, our data indicate that extra-nuclear TERT is involved in reducing the effect of excessive OS, thus promoting cancer cell survival. Extra-nuclear TERT may thus represent a marker of cancer progression and a possible therapeutic target in PTC.

Autophagy sustains mitochondrial respiration and determines resistance to BRAFV600E inhibition in thyroid carcinoma cells.

BRAFV600E is the most prevalent mutation in thyroid cancer and correlates with poor prognosis and therapy resistance. Although selective inhibitors of BRAFV600E have been developed, more advanced tumors such as anaplastic thyroid carcinomas show a poor response in clinical trials. Therefore, the study of alternative survival mechanisms is needed. Since metabolic changes have been related to malignant progression, in this work we explore metabolic dependencies of thyroid tumor cells to exploit them therapeutically. Our results show that respiration of thyroid carcinoma cells is highly dependent on fatty acid oxidation and, in turn, fatty acid mitochondrial availability is regulated through macroautophagy/autophagy. Furthermore, we show that both lysosomal inhibition and the knockout of the essential autophagy gene, ATG7, lead to enhanced lipolysis; although this effect is not essential for survival of thyroid carcinoma cells. We also demonstrate that following inhibition of either autophagy or fatty acid oxidation, thyroid tumor cells compensate oxidative phosphorylation deficiency with an increase in glycolysis. In contrast to lipolysis induction, upon autophagy inhibition, glycolytic boost in autophagy-deficient cells is essential for survival and, importantly, correlates with a higher sensitivity to the BRAFV600E selective inhibitor, vemurafenib. In agreement, downregulation of the glycolytic pathway results in enhanced mitochondrial respiration and vemurafenib resistance. Our work provides new insights into the role of autophagy in thyroid cancer metabolism and supports mitochondrial targeting in combination with vemurafenib to eliminate BRAFV600E-positive thyroid carcinoma cells.Abbreviations: AMP: adenosine monophosphate; ATC: anaplastic thyroid carcinoma; ATG: autophagy related; ATP: adenosine triphosphate; BRAF: B-Raf proto-oncogene, serine/threonine kinase; Cas9: CRISPR-associated protein; CREB: cAMP responsive element binding protein; CRISPR: clustered regularly interspaced short palindromic repeats; 2DG: 2-deoxyglucose; FA: fatty acid; FAO: fatty acid oxidation; FASN: fatty acid synthase; FCCP: trifluoromethoxy carbonyl cyanide phenylhydrazone; LAMP1: lysosomal associated membrane protein 1; LIPE/HSL: lipase E, hormone sensitive type; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; OCR: oxygen consumption rate; OXPHOS: oxidative phosphorylation; PRKA/PKA: protein kinase cAMP-activated; PTC: papillary thyroid carcinoma; SREBF1/SREBP1: sterol regulatory element binding transcription factor 1.

Mechanisms of vemurafenib-induced anti-tumor effects in ATC FRO cells.

Background: Anaplastic Thyroid Carcinoma (ATC) is a rare and deadly malignant tumor in humans. It is prone to developing resistance to radiotherapy and chemotherapy. Molecular targeted therapy offers a novel way to treat ATC. The BRAF mutation is closely associated with many cancers, including thyroid carcinoma. Vemurafenib, a small-molecule inhibitor, is specifically designed to target the mutant serine/threonine kinase BRAF. The objective of this study is to elucidate the regulatory mechanisms underlying the effects of vemurafenib on human anaplastic thyroid carcinoma cell line FRO and to assess its potential therapeutic role. Methods: The effects of vemurafenib on the proliferation of FRO cells were assessed by the CCK-8 method and Colony-forming assay. Transwell chambers and scratch tests were employed to examine the impact of vemurafenib on the invasion and migration of FRO cells. Apoptosis and cycle distribution of FRO cells were analyzed by tunel assay and flow cytometry. The effects of vemurafenib on the expression of BRAF-activated non-protein coding RNA (BANCR), Bax, Bcl2, and E-cadherin were evaluated by qRT-PCR. Furthermore, the effects of vemurafenib on the expression of phosphoinositol-3-kinase (PI3K)/phosphoinositol-3-kinase (AKT) pathway-related proteins, BRAF, CyclinD1, Bcl-2, Bax, and E-cadherin proteins in FRO cells were investigated through the western-blot method. All experiments were conducted in three replicates. Results: Vemurafenib was observed to inhibit proliferation and induce apoptosis in a dose- and time-dependent manner (P < 0.05). The formation of FRO cell colonies, as well as migration and invasion, all showed a dose-dependent reduction (P < 0.05). Flow cytometric analysis indicated G0/G1 cell cycle arrest (P < 0.05). QRT-PCR revealed that vemurafenib could suppress the expression of BANCR and Bcl2 while increasing the expression of Bax and E-cadherin in a dose-dependent manner (P < 0.05). The protein expression levels of Bax and E-cadherin were up-regulated significantly, and the expression levels of BRAF, CyclinD1, Bcl-2, p-PI3K, p-AKT, and p-mTOR were markedly down-regulated with increasing concentrations of vemurafenib (P < 0.05). Conclusions: The proliferation and metastasis of FRO cells can be suppressed by vemurafenib through the silencing of BRAF and BANCR expression, inhibition of PI3K/AKT signaling pathway activation, induction of apoptosis, and cell cycle arrest.

Evodiamine inhibits growth of vemurafenib drug-resistant melanoma via suppressing IRS4/PI3K/AKT signaling pathway.

Evodiamine, a novel alkaloid, was isolated from the fruit of tetradium. It exerts a diversity of pharmacological effects and has been used to treat gastropathy, hypertension, and eczema. Several studies reported that evodiamine has various biological effects, including anti-nociceptive, anti-bacterial, anti-obesity, and anti-cancer activities. However, there is no research regarding its effects on drug-resistant cancer. This study aimed to investigate the effect of evodiamine on human vemurafenib-resistant melanoma cells (A375/R cells) proliferation ability and its mechanism. Cell activity was assessed using the cell counting kit-8 (CCK-8) method. Flow cytometry assay was used to assess cell apoptosis and cell cycle. A xenograft model was used to analyze the inhibitory effects of evodiamine on tumor growth. Bioinformatics analyses, network pharmacology, and molecular docking were used to explore the potential mechanism of evodiamine in vemurafenib-resistant melanoma. RT-qPCR and Western blotting were performed to reveal the molecular mechanism. The alkaloid extract of the fruit of tetradium, evodiamine showed the strongest tumor inhibitory effect on vemurafenib-resistant melanoma cells compared to treatment with vemurafenib alone. Evodiamine inhibited vemurafenib-resistant melanoma cell growth, proliferation, and induced apoptosis, conforming to a dose-effect relationship and time-effect relationship. Results from network pharmacology and molecular docking suggested that evodiamine might interact with IRS4 to suppress growth of human vemurafenib-resistant melanoma cells. Interestingly, evodiamine suppressed IRS4 expression and then inhibited PI3K/AKT signaling pathway, and thus had the therapeutic action on vemurafenib-resistant melanoma.

Multisystem Erdheim-Chester disease presenting with pericardial effusion confirmed by the effusion cytology specimen.

Erdheim-Chester disease (ECD) is a rare histiocytosis characterized by the foamy CD68+CD1a- histiocytes infiltrating multiple organs and tissues. ECD might be asymptomatic or present with variable manifestations. The diagnosis of ECD requires characteristic radiological findings and pathological features. Herein, we described a 52-year-old female patient who was admitted to our hospital for recurrent pericardial effusion for two months. She has a medical history of papillary thyroid carcinoma (PTC) and underwent a total thyroidectomy two years before admission. The radiological findings suggested a potential diagnosis of ECD. Cytological analysis of the effusion cytology specimen revealed CD68+CD1a- histiocytes, confirming the ECD diagnosis. The BRAF V600E mutation was identified in the histiocytes, prompting the administration of vemurafenib, a BRAF inhibitor. After two months of standard-dose vemurafenib treatment, the disease was well controlled with pericardial effusion regression.

Vemurafenib combined with chemotherapy achieved sustained remission in pediatric LCH: a multi-center observational study.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a myeloid neoplasia with potentially fatal consequences, and about 2/3 of cases involve the BRAFV600E kinase-activated mutation. Vemurafenib, a BRAF inhibitor, has demonstrated significant clinical improvements in LCH. However, the high relapse rate of LCH following cessation of vemurafenib therapy remains a major challenge, and alternative treatment strategies require further investigation. METHODS: In this retrospective multi-center study, we evaluated the efficacy and safety of vemurafenib combined with conventional chemotherapy in patients with severe or refractory LCH. RESULTS: Seventeen patients were enrolled in the study, with eleven classified as risk organ involvement (RO +). Six received the combination therapy as the primary treatment, and eleven after being refractory to prior chemotherapy. The overall response rate was 94.1%. Progression-free survival among all 17 patients was 70.6% (12/17) at a median follow-up of 32 months, and relapse-free survival among the 15 patients with discontinuation after a response was 73.3%(11/15) at a median follow-up of 34 months. Five of six patients (83.3%) with myeloid BRAFV600E mutations demonstrated molecular remission. The overall survival rate was 100%. Adverse events were mostly classified as grades 1 or 2. CONCLUSION: Our data suggest that the combination of vemurafenib and chemotherapy can achieve sustained clinical and molecular level relief in children with LCH, and side effects are tolerable.

Vemurafenib induces senescence in acute myeloid leukemia and myelodysplastic syndrome by activating the HIPPO signaling pathway: implications for potential targeted therapy.

BACKGROUND: The outcome of Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) remain dismal despite the development of treatment. Targeted therapy is gaining more and more attention in improving prognosis. METHODS: Expression of BRAF was analyzed by RT-qPCR in AML and MDS patients. Cells viability treated by drugs was measured by CCK-8 assay. Network pharmacology and RNA-sequence were used to analyze the mechanism of drugs and verified in vitro and xenograft tumor model. RESULTS: Here we showed that BRAF was overexpressed in AML and MDS patients, and correlated with poor prognosis. The BRAF inhibitor-Vemurafenib (VEM) could significantly induce senescence, proliferation inhibition and apoptosis in AML cells, which can be enhanced by Bortezomib (BOR). This inhibitory effect was also verified in CD34 + cells derived from AML patients. Mechanistically, we showed that VEM combined with BOR could turn on HIPPO signaling pathway, thereby inducing cellular senescence in AML cells and xenograft mouse. CONCLUSIONS: Taken together, our findings demonstrate a significant upregulation of BRAF expression in AML and MDS patients, which is associated with unfavorable clinical outcomes. We also discovered that the BRAF inhibitor Vemurafenib induces cellular senescence through activation of the HIPPO signaling pathway. Analysis of BRAF expression holds promise as a prognostic indicator and potential therapeutic target for individuals with AML and MDS.

A Quality by Design Approach for Developing SNEDDS Loaded with Vemurafenib for Enhanced Oral Bioavailability.

Vemurafenib (VMF) is a practically insoluble (< 0.1 µg/mL) and least bioavailable (1%) drug. To enhance its oral bioavailability and solubility, we formulated a reliable self-nano emulsifying drug delivery system (SNEDDS). A Quality by Design (QbD) approach was used to optimize the ratio of Capryol 90, Tween 80, and Transcutol HP. VMF-loaded SNEDDS was characterized for its size, polydispersity index (PDI), zeta potential, drug content, and transmittance. The in vitro release profile of the drug loaded in SNEDDS was compared to the free drug in two media, pH 6.8 and 1.2, and the data obtained were analyzed with different mathematical models. A reverse-phase ultra-pressure liquid chromatography (UPLC) technique with high sensitivity and selectivity was developed and validated for the quantification of VMF in analytical and bioanalytical samples. Dissolution efficiency for SNEDDS was estimated using different models, which proved that the developed novel SNEDDS formulation had a better in vitro dissolution profile than the free drug. A 2.13-fold enhanced oral bioavailability of VMF-loaded SNEDDS compared to the free drug demonstrates the superiority of the developed formulation. This work thus presents an overview of VMF-loaded SNEDDS as a promising alternative to improve the oral bioavailability of the drug.

Erdheim-Chester disease of brain parenchyma without any systemic involvement: A case report and review of literature.

Erdheim-Chester disease is a non-Langerhans cell histiocytosis syndrome characterised by histiocytic infiltration of different organs and systems in the body. Erdheim-Chester disease with isolated central nervous system (CNS) involvement causes diagnostic difficulties due to the absence of systemic findings and may result in misdiagnosis and inaccurate treatment choices. The case discussed in this report exemplifies how challenging it is to diagnose Erdheim-Chester disease with isolated CNS involvement. This case, which presented with progressive pyramidocerebellar syndrome, was clinically and radiologically resistant to all immunosuppressive and immunomodulatory treatments administered. The presence of false negative results in repeated histopathological investigations and the absence of evidence for systemic disease hindered the diagnosis and treatment work-up. In this study, we reviewed and discussed the prominent features of the presented case in light of the relevant literature.

Acquired and intrinsic resistance to vemurafenib in BRAFV600E -driven melanoma brain metastases.

BRAFV600 -mutated melanoma brain metastases (MBMs) are responsive to BRAF inhibitors, but responses are generally less durable than those of extracranial metastases. We tested the hypothesis that the drug efflux transporters P-glycoprotein (P-gp; ABCB1) and breast cancer resistance protein (BCRP; ABCG2) expressed at the blood-brain barrier (BBB) offer MBMs protection from therapy. We intracranially implanted A375 melanoma cells in wild-type (WT) and Abcb1a/b;Abcg2-/- mice, characterized the tumor BBB, analyzed drug levels in plasma and brain lesions after oral vemurafenib administration, and determined the efficacy against brain metastases and subcutaneous lesions. Although contrast-enhanced MRI demonstrated that the integrity of the BBB is disrupted in A375 MBMs, vemurafenib achieved greater antitumor efficacy against MBMs in Abcb1a/b;Abcg2-/- mice compared with WT mice. Concordantly, P-gp and BCRP are expressed in MBM-associated brain endothelium both in patients and in A375 xenografts and expression of these transporters limited vemurafenib penetration into A375 MBMs. Although initially responsive, A375 MBMs rapidly developed therapy resistance, even in Abcb1a/b;Abcg2-/- mice, and this was unrelated to pharmacokinetic or target inhibition issues. Taken together, we demonstrate that both intrinsic and acquired resistance can play a role in MBMs.