Dabrafenib; preclinical characterization, increased efficacy when combined with trametinib, while BRAF/MEK tool combination reduced skin lesions

Non-kinase off-target inhibitory activities of clinically-relevant kinase inhibitors

Protein kinases are responsible for a myriad of cellular functions, such as cell cycle, apoptosis, and proliferation. Because of this, kinases make excellent targets for therapeutics. During the process to identify clinical kinase inhibitor candidates, kinase selectivity profiles of lead inhibitors are typically obtained. Such kinome selectivity screening could identify crucial kinase anti-targets that might contribute to drug toxicity and/or reveal additional kinase targets that potentially contribute to the efficacy of the compound via kinase polypharmacology. In addition to kinome panel screening, practitioners also obtain the inhibition profiles of a few non-kinase targets, such as ion-channels and select GPCR targets to identify compounds that might possess potential liabilities. Often ignored is the possibility that identified kinase inhibitors might also inhibit or bind to the other proteins (greater than 20,000) in the cell that are not kinases, which may be relevant to toxicity or even additional mode of drug action. This review highlights various inhibitors, which have been approved by the FDA or are currently undergoing clinical trials, that also inhibit other non-kinase targets. The binding poses of the drugs in the binding sites of the target kinases and off-targets are analyzed to understand if the same features of the compounds are critical for the polypharmacology.

Human/mouse CD137 agonist, JNU-0921, effectively shrinks tumors through enhancing the cytotoxicity of CD8+ T cells in cis and in trans

Agonistic antibodies against CD137 have been demonstrated to completely regress established tumors through activating T cell immunity. Unfortunately, current CD137 antibodies failed to benefit patients with cancer. Moreover, their antitumor mechanisms in vivo remain to be determined. Here, we report the development of a small molecular CD137 agonist, JNU-0921. JNU-0921 effectively activates both human and mouse CD137 through direct binding their extracellular domains to induce oligomerization and signaling and effectively shrinks tumors in vivo. Mechanistically, JNU-0921 enhances effector and memory function of cytotoxic CD8+ T cells (CTLs) and alleviates their exhaustion. JNU-0921 also skews polarization of helper T cells toward T helper 1 type and enhances their activity to boost CTL function. Meanwhile, JNU-0921 attenuates the inhibitory function of regulatory T cells on CTLs. Our current work shows that JNU-0921 shrinks tumors by enhancing the cytotoxicity of CTLs in cis and in trans and sheds light on strategy for developing CD137 small molecular agonists.

The effects of dabrafenib and/or trametinib treatment in Braf V600-mutant glioma: a systematic review and meta-analysis

This study aimed to evaluate the effects of dabrafenib and/or trametinib therapy in BRAF v600-mutant glioma treatment. PubMed, the Cochrane Library, EMBASE and Web of Science were searched from inception to Sep 2023. Inclusion criteria were designed based on the PICO principle to select relevant articles. Search keywords included 'dabrafenib', 'trametinib', 'glioma' and other related keywords. Outcomes included overall survival (OS), progression-free survival (PFS), adverse events (AEs), and death events. Methodological index for non-randomized studies (MINORS) was used to assess the methodological quality. Stata 14.0 was selected to perform the Cochrane Q and I2 statistics to test the heterogeneity among all studies. As for publication bias assessment and sensitivity analysis, the funnel plot, Egger regression test, Begg test, and trim and fill method were selected. Including 8 studies for meta-analysis. The pooled results of the single-arm trials showed that the median PFS and median OS after treatment were 6.10 months and 22.73 months, respectively. Notably, this study found a high incidence of AEs and death events of 50% and 43% after treatment. All the above findings were statistically significant. Also, this study statistically supported the advantage of disease response improvement after the combination therapy in BRAF v600-mutant glioma patients, which were shown as a pooled rate of PR (30%), a pooled rate of CR (18%), and a pooled rate of ORR (39%). And the AE rate was lower in the monotherapy group (AE: 25%) than in the combination treatment group (AE: 60%). Sensitivity analysis indicated that all the results were robust. Based on current literature outcomes, dabrafenib and/or trametinib may lead to the median PFS of 6.10 months and median OS as 22.73 months for BRAF v600-mutant glioma patients, and the safety of monotherapy is better than that of combination therapy. This conclusion needs to be treated with caution and further verified.

The Genetic Analysis and Clinical Therapy in Lung Cancer: Current Advances and Future Directions

Lung cancer, including both non-small cell lung cancer and small cell lung cancer, remains the leading cause of cancer-related mortality worldwide, representing 18% of the total cancer deaths in 2020. Many patients are identified already at an advanced stage with metastatic disease and have a worsening prognosis. Recent advances in the genetic understanding of lung cancer have opened new avenues for personalized treatments and targeted therapies. This review examines the latest discoveries in the genetics of lung cancer, discusses key biomarkers, and analyzes current clinical therapies based on this genetic information. It will conclude with a discussion of future prospects and potential research directions.

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part I

A multitude of TKI has been developed and approved targeting various oncogenetic alterations. While these have provided improvements in efficacy compared with conventional chemotherapies, resistance to targeted therapies occurs. Mutations in the kinase domain result in the inability of TKI to inactivate the protein kinase. Also, gene amplification, increased protein expression and downstream activation or bypassing of signalling pathways are commonly reported mechanisms of resistance. Improved understanding of mechanisms involved in TKI resistance has resulted in the development of new generations of targeted agents. In a race against time, the search for new, more potent and efficient drugs, and/or combinations of drugs, remains necessary as new resistance mechanisms to the latest generation of TKI emerge. This review examines the various generations of TKI approved to date and their common mechanisms of resistance, focusing on TKI targeting BCR-ABL, epidermal growth factor receptor, anaplastic lymphoma kinase and BRAF/MEK tyrosine kinases.

Trametinib, a MEK1/2 Inhibitor, Protects Mice from Cisplatin- and Noise-Induced Hearing Loss

Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high-decibel noises are two of the most common causes of hearing loss. The mitogen-activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective against noise- and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin-induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective against hearing loss in vivo. In this study, we demonstrate that trametinib protects against cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor-killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin, but lower doses of the drug were protective against hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects against both insults of hearing loss, as well as that targeting all three kinases in the MAPK pathway protects mice from cisplatin- and noise-induced hearing loss.

Skin Malignancies Due to Anti-Cancer Therapies

Skin cancers involve a significant concern in cancer therapy due to their association with various treatment modalities. This comprehensive review explores the increased risk of skin cancers linked to different anti-cancer treatments, including classic immunosuppressants such as methotrexate (MTX), chemotherapeutic agents such as fludarabine and hydroxyurea (HU), targeted therapies like ibrutinib and Janus Kinase inhibitors (JAKi), mitogen-activated protein kinase pathway (MAPKP) inhibitors, sonic hedgehog pathway (SHHP) inhibitors, and radiotherapy. MTX, a widely used immunosuppressant in different fields, is associated with basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and cutaneous melanoma (CM), particularly at higher dosages. Fludarabine, HU, and other chemotherapeutic agents increase the risk of non-melanoma skin cancers (NMSCs), including cSCC and BCC. Targeted therapies like ibrutinib and JAKi have been linked to an elevated incidence of NMSCs and CM. MAPKP inhibitors, particularly BRAF inhibitors like vemurafenib, are associated with the development of cSCCs and second primary melanomas (SPMs). SHHP inhibitors like vismodegib have been linked to the emergence of cSCCs following treatment for BCC. Additionally, radiotherapy carries carcinogenic risks, especially for BCCs, with increased risks, especially with younger age at the moment of exposure. Understanding these risks and implementing appropriate screening is crucial for effectively managing patients undergoing anti-cancer therapies.

FDA-Approved MEK1/2 Inhibitor, Trametinib, Protects Mice from Cisplatin and Noise-Induced Hearing Loss

Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high decibel noises are two of the most common causes of hearing loss. The mitogen activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective from noise and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective from hearing loss in vivo. In this study, we demonstrate that trametinib protects from cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin but lower doses of the drug were protective from hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects from both insults of hearing loss and that targeting all three kinases in the MAPK pathway protect from cisplatin and noise-induced hearing loss in mice.

Simulating BRAFV600E-MEK-ERK signalling dynamics in response to vertical inhibition treatment strategies

In vertical inhibition treatment strategies, multiple components of an intracellular pathway are simultaneously inhibited. Vertical inhibition of the BRAFV600E-MEK-ERK signalling pathway is a standard of care for treating BRAFV600E-mutated melanoma where two targeted cancer drugs, a BRAFV600E-inhibitor, and a MEK inhibitor, are administered in combination. Targeted therapies have been linked to early onsets of drug resistance, and thus treatment strategies of higher complexities and lower doses have been proposed as alternatives to current clinical strategies. However, finding optimal complex, low-dose treatment strategies is a challenge, as it is possible to design more treatment strategies than are feasibly testable in experimental settings. To quantitatively address this challenge, we develop a mathematical model of BRAFV600E-MEK-ERK signalling dynamics in response to combinations of the BRAFV600E-inhibitor dabrafenib (DBF), the MEK inhibitor trametinib (TMT), and the ERK-inhibitor SCH772984 (SCH). From a model of the BRAFV600E-MEK-ERK pathway, and a set of molecular-level drug-protein interactions, we extract a system of chemical reactions that is parameterised by in vitro data and converted to a system of ordinary differential equations (ODEs) using the law of mass action. The ODEs are solved numerically to produce simulations of how pathway-component concentrations change over time in response to different treatment strategies, i.e., inhibitor combinations and doses. The model can thus be used to limit the search space for effective treatment strategies that target the BRAFV600E-MEK-ERK pathway and warrant further experimental investigation. The results demonstrate that DBF and DBF-TMT-SCH therapies show marked sensitivity to BRAFV600E concentrations in silico, whilst TMT and SCH monotherapies do not.

KSR1 Knockout Mouse Model Demonstrates MAPK Pathway's Key Role in Cisplatin- and Noise-induced Hearing Loss

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared with their wild-type KSR1 littermates. KSR1 is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK1/2 and ERK1/2 and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. KSR1, BRAF, MEK1/2, and ERK1/2 are all ubiquitously expressed in the cochlea. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in male and female mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, protected male and female KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induced hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

BRAFV600E-mutant metastatic NSCLC: disease overview and treatment landscape

In this review, we cover the current understanding of BRAF mutations and associated clinical characteristics in patients with metastatic NSCLC, approved and emerging treatment options, BRAF sequencing approaches, and unmet needs. The BRAFV600E mutation confers constitutive activity of the MAPK pathway, leading to enhanced growth, proliferation, and survival of tumor cells. Testing for BRAF mutations enables patients to be treated with therapies that directly target BRAFV600E and the MAPK pathway, but BRAF testing lags behind other oncogene testing in metastatic NSCLC. Additional therapies targeting BRAFV600E mutations provide options for patients with metastatic NSCLC. Emerging therapies and combinations under investigation could potentially overcome issues of resistance and target non-V600E mutations. Therefore, because targeted therapies with enhanced efficacy are on the horizon, being able to identify BRAF mutations in metastatic NSCLC may become even more important.

Dabrafenib and steroids for the treatment of Erdheim-Chester disease with extensive CNS involvement: a case report

Erdheim-Chester disease (ECD) is an exceedingly rare non-Langerhans cell CD68+ CD1a- S100- histiocytic multi-organ disease. Diagnosis of ECD is often delayed due to non-specific radiographic findings and heterogeneous lesional tissue. Increasingly, the role of genomic alterations is being recognized for both diagnosis and treatment of ECD. More than half of ECD patients harbor the BRAFV600E mutation. Evaluation for this mutation be can falsely negative on immunohistochemical staining and confirmation with molecular analyses is recommended. We present a case of the 44 year-old male with BRAFV600E-positive ECD treated successfully with steroids followed by single-agent dabrafenib.

Clinical Response of Advanced Lung Adenocarcinoma with Class III BRAF G466V Missense Mutation to Dabrafenib and Trametinib: A Case Report

Aim

BRAF is a pivotal driver gene in cancer development. Based on this, the combination of dabrafenib and trametinib was approved for treating NSCLC patients with BRAFV600E mutations. However, the majority of BRAF mutations in lung cancer are non-V600E variants, particularly class III mutants, which currently lack targeted therapeutic options and result in unfavorable clinical outcomes.

Case Presentation

We present a case of advanced lung adenocarcinoma with a class III BRAFG466V mutation. The patient experienced significant pleural and pericardial effusion, leading to chest tightness and an inability to lie flat. Severe pain and limited mobility from lumbar destruction seriously affected the patient's quality of life. Due to the patient's intolerance to chemotherapy, dabrafenib and trametinib combination therapy was chosen. After three months of targeted therapy, the patient's overall condition significantly improved, enabling self-care, and achieving partial response (PR) as an indicator of treatment efficacy.

Conclusion

The combination therapy of dabrafenib and trametinib demonstrates remarkable clinical benefits for lung adenocarcinoma patients with the BRAFG466V mutation. Targeted therapy should be considered for patients with BRAF class III mutations, especially those in poor general condition and may not tolerate chemotherapy.

MEK-inhibitors decrease Nfix in muscular dystrophy but induce unexpected calcifications, partially rescued with Cyanidin diet

Muscular dystrophies (MDs) are incurable genetic myopathies characterized by progressive degeneration of skeletal muscles. Dystrophic mice lacking the transcription factor Nfix display morphological and functional improvements of the disease. Recently, we demonstrated that MAPK signaling pathway positively regulates Nfix in muscle development and that Cyanidin, a natural antioxidant molecule, strongly ameliorates the pathology. To explore a synergistic approach aimed at treating MDs, we administered Trametinib, a clinically approved MEK inhibitor, alone or combined with Cyanidin to adult Sgca null mice. We observed that chronic treatment with Trametinib and Cyanidin reduced Nfix in myogenic cells but, unexpectedly, caused ectopic calcifications exclusively in dystrophic muscles. The combined treatment with Cyanidin resulted in histological improvements by preventing Trametinib-induced calcifications in Diaphragm and Soleus. Collectively, this first pilot study revealed that Nfix is modulated by the MAPK pathway in MDs, and that Cyanidin partly rescued the unexpected ectopic calcifications caused by MEK inhibition.

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

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.

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.

A Clinical Viewpoint on the Use of Targeted Therapy in Advanced Gastric Cancer

The development of therapies for advanced gastric cancer (GC) has made significant progress over the past few years. The identification of new molecules and molecular targets is expanding our understanding of the disease's intricate nature. The end of the classical oncology era, which relied on well-studied chemotherapeutic agents, is giving rise to novel and unexplored challenges, which will cause a significant transformation of the current oncological knowledge in the next few years. The integration of established clinically effective regimens in additional studies will be crucial in managing these innovative aspects of GC. This study aims to present an in-depth and comprehensive review of the clinical advancements in targeted therapy and immunotherapy for advanced GC.

The current landscape of using direct inhibitors to target KRASG12C-mutated NSCLC

Mutation in KRAS protooncogene represents one of the most common genetic alterations in NSCLC and has posed a great therapeutic challenge over the past ~ 40 years since its discovery. However, the pioneer work from Shokat's lab in 2013 has led to a recent wave of direct KRASG12C inhibitors that utilize the switch II pocket identified. Notably, two of the inhibitors have recently received US FDA approval for their use in the treatment of KRASG12C mutant NSCLC. Despite this success, there remains the challenge of combating the resistance that cell lines, xenografts, and patients have exhibited while treated with KRASG12C inhibitors. This review discusses the varying mechanisms of resistance that limit long-lasting effective treatment of those direct inhibitors and highlights several novel therapeutic approaches including a new class of KRASG12C (ON) inhibitors, combinational therapies across the same and different pathways, and combination with immunotherapy/chemotherapy as possible solutions to the pressing question of adaptive resistance.

Recent advances in non-small cell lung cancer targeted therapy; an update review

Lung cancer continues to be the leading cause of cancer-related death worldwide. In the last decade, significant advancements in the diagnosis and treatment of lung cancer, particularly NSCLC, have been achieved with the help of molecular translational research. Among the hopeful breakthroughs in therapeutic approaches, advances in targeted therapy have brought the most successful outcomes in NSCLC treatment. In targeted therapy, antagonists target the specific genes, proteins, or the microenvironment of tumors supporting cancer growth and survival. Indeed, cancer can be managed by blocking the target genes related to tumor cell progression without causing noticeable damage to normal cells. Currently, efforts have been focused on improving the targeted therapy aspects regarding the encouraging outcomes in cancer treatment and the quality of life of patients. Treatment with targeted therapy for NSCLC is changing rapidly due to the pace of scientific research. Accordingly, this updated study aimed to discuss the tumor target antigens comprehensively and targeted therapy-related agents in NSCLC. The current study also summarized the available clinical trial studies for NSCLC patients.

Challenges and Opportunities in the Crusade of BRAF Inhibitors: From 2002 to 2022

Serine/threonine-protein kinase B-Raf (BRAF; RAF = rapidly accelerated fibrosarcoma) plays an important role in the mitogen-activated protein kinase (MAPK) signaling cascade. Somatic mutations in the BRAF gene were first discovered in 2002 by Davies et al., which was a major breakthrough in cancer research. Subsequently, three different classes of BRAF mutants have been discovered. This class includes class I monomeric mutants (BRAFV600), class II BRAF homodimer mutants (non-V600), and class III BRAF heterodimers (non-V600). Cancers caused by these include melanoma, thyroid cancer, ovarian cancer, colorectal cancer, nonsmall cell lung cancer, and others. In this study, we have highlighted the major binding pockets in BRAF protein, their active and inactive conformations with inhibitors, and BRAF dimerization and its importance in paradoxical activation and BRAF mutation. We have discussed the first-, second-, and third-generation drugs approved by the Food and Drug Administration and drugs under clinical trials with all four different binding approaches with DFG-IN/OUT and αC-IN/OUT for BRAF protein. We have investigated particular aspects and difficulties with all three generations of inhibitors. Finally, this study has also covered recent developments in synthetic BRAF inhibitors (from their discovery in 2002 to 2022), their unique properties, and importance in inhibiting BRAF mutants.

Unraveling the Roles of miR-204-5p and HMGA2 in Papillary Thyroid Cancer Tumorigenesis

Thyroid cancer is the most common endocrine malignant tumor with an increasing incidence rate. Although differentiated types of thyroid cancer generally present good clinical outcomes, some dedifferentiate into aggressive and lethal forms. However, the molecular mechanisms governing aggressiveness and dedifferentiation are still poorly understood. Aberrant expression of miRNAs is often correlated to tumor development, and miR-204-5p has previously been identified in papillary thyroid carcinoma as downregulated and associated with aggressiveness. This study aimed to explore its role in thyroid tumorigenesis. To address this, gain-of-function experiments were performed by transiently transfecting miR-204-5p in thyroid cancer cell lines. Then, the clinical relevance of our data was evaluated in vivo. We prove that this miRNA inhibits cell invasion by regulating several targets associated with an epithelial-mesenchymal transition, such as SNAI2, TGFBR2, SOX4 and HMGA2. HMGA2 expression is regulated by the MAPK pathway but not by the PI3K, IGF1R or TGFβ pathways, and the inhibition of cell invasion by miR-204-5p involves direct binding and repression of HMGA2. Finally, we confirmed in vivo the relationship between miR-204-5p and HMGA2 in human PTC and a corresponding mouse model. Our data suggest that HMGA2 inhibition offers promising perspectives for thyroid cancer treatment.

Establishment of a BRAF V595E-mutant canine prostate cancer cell line and the antitumor effects of MEK inhibitors against canine prostate cancer

Canine prostate cancer (cPCa) is a malignant neoplasm with no effective therapy. The BRAF V595E mutation, corresponding to the human BRAF V600E mutation, is found frequently in cPCa. Activating BRAF mutations are recognized as oncogenic drivers, and blockade of MAPK/ERK phosphorylation may be an effective therapeutic target against BRAF-mutated tumours. The aim of this study was to establish a novel cPCa cell line and to clarify the antitumor effects of MEK inhibitors on cPCa in vitro and in vivo. We established the novel CHP-2 cPCa cell line that was derived from the prostatic tissue of a cPCa patient. Sequencing of the canine BRAF gene in two cPCa cell lines revealed the presence of the BRAF V595E mutation. MEK inhibitors (trametinib, cobimetinib and mirdametinib) strongly suppressed cell proliferation in vitro, and trametinib showed the highest efficacy against cPCa cells with minimal cytotoxicity to non-cancer COPK cells. Furthermore, we orally administered 0.3 or 1.0 mg/kg trametinib to CHP-2 xenografted mice and examined its antitumor effects in vivo. Trametinib reduced tumour volume, decreased phosphorylated ERK levels, and lowered Ki-67 expression in xenografts in a dose-dependent manner. Although no clear adverse events were observed with administration, trametinib-treated xenografts showed osteogenesis that was independent of dosage. Our results indicate that trametinib induces cell cycle arrest by inhibiting ERK activation, resulting in cPCa tumour regression in a dose-dependent manner. MEK inhibitors, in addition to BRAF inhibitors, may be a targeted agent option for cPCa with the BRAF V595E mutation.

Dabrafenib plus trametinib in BRAFV600E-mutated rare cancers: the phase 2 ROAR trial

BRAFV600E alterations are prevalent across multiple tumors. Here we present final efficacy and safety results of a phase 2 basket trial of dabrafenib (BRAF kinase inhibitor) plus trametinib (MEK inhibitor) in eight cohorts of patients with BRAFV600E-mutated advanced rare cancers: anaplastic thyroid carcinoma (n = 36), biliary tract cancer (n = 43), gastrointestinal stromal tumor (n = 1), adenocarcinoma of the small intestine (n = 3), low-grade glioma (n = 13), high-grade glioma (n = 45), hairy cell leukemia (n = 55) and multiple myeloma (n = 19). The primary endpoint of investigator-assessed overall response rate in these cohorts was 56%, 53%, 0%, 67%, 54%, 33%, 89% and 50%, respectively. Secondary endpoints were median duration of response (DoR), progression-free survival (PFS), overall survival (OS) and safety. Median DoR was 14.4 months, 8.9 months, not reached, 7.7 months, not reached, 31.2 months, not reached and 11.1 months, respectively. Median PFS was 6.7 months, 9.0 months, not reached, not evaluable, 9.5 months, 5.5 months, not evaluable and 6.3 months, respectively. Median OS was 14.5 months, 13.5 months, not reached, 21.8 months, not evaluable, 17.6 months, not evaluable and 33.9 months, respectively. The most frequent (≥20% of patients) treatment-related adverse events were pyrexia (40.8%), fatigue (25.7%), chills (25.7%), nausea (23.8%) and rash (20.4%). The encouraging tumor-agnostic activity of dabrafenib plus trametinib suggests that this could be a promising treatment approach for some patients with BRAFV600E-mutated advanced rare cancers. ClinicalTrials.gov registration: NCT02034110 .

Clinical and molecular overview of immunotherapeutic approaches for malignant skin melanoma: Past, present and future

Traditional therapeutic approaches for malignant melanoma, have proved to be limited and/or ineffective, especially with respect to their role in improving patient survival and tumor recurrence. In this regard, immunotherapy has been demonstrated to be a promising therapeutic alternative, boosting antitumor responses through the modulation of cell signaling pathways involved in the effector mechanisms of the immune system, particularly, the so-called "immunological checkpoints". Clinical studies on the efficacy and safety of immunotherapeutic regimens, alone or in combination with other antitumor approaches, have increased dramatically in recent decades, with very encouraging results. Hence, this review will discuss the current immunotherapeutic regimens used to treat malignant melanoma, as well as the molecular and cellular mechanisms involved. In addition, current clinical studies that have investigated the use, efficacy, and adverse events of immunotherapy in melanoma will also be discussed.

Design and biological characterization of a series of dual mechanism ERK1/2 inhibitors with a Triazolopyridinone core

Oncology clinical development programs have targeted the RAS/RAF/MEK/ERK signaling pathway with small molecule inhibitors for a variety of cancers during the past decades, and most therapies have shown limited or minimal success. Specific BRAF and MEK inhibitors have shown clinical efficacy in patients for the treatment of BRAF-mutant melanoma. However, most cancers have shown treatment resistance after several months of inhibitor usage, and reports indicate resistance is often associated with the reactivation of the MAPK signaling pathway. It is widely accepted that an effective MAPK therapy will have a significant impact on curtailing cancer growth and improving patient survival. However, despite more than three decades of intense research and pharmaceutical industry efforts, an FDA-approved, effective anti-cancer ERK inhibitor has yet to be developed. Here, we present the design, optimization, and biological characterization of ERK1/2 inhibitors that block catalytic phosphorylation of downstream substrates such as RSK but also modulate the phosphorylation of ERK1/2 by MEK without directly inhibiting MEK. Our series of dual mechanism ERK1/2 inhibitors, in which we incorporated a triazolopyridinone core, may present potential benefits for enhancing efficacy and addressing the emergence of treatment resistance.

Evolution of the Targeted Therapy Landscape for Cholangiocarcinoma: Is Cholangiocarcinoma the 'NSCLC' of GI Oncology?

In the past two decades, molecular targeted therapy has revolutionized the treatment landscape of several malignancies. Lethal malignancies such as non-small cell lung cancer (NSCLC) have become a model for precision-matched immune- and gene-targeted therapies. Multiple small subgroups of NSCLC defined by their genomic aberrations are now recognized; remarkably, taken together, almost 70% of NSCLCs now have a druggable anomaly. Cholangiocarcinoma (CCA) is a rare tumor with a poor prognosis. Novel molecular alterations have been recently identified in patients with CCA, and the potential for targeted therapy is being realized. In 2019, a fibroblast growth factor receptor 2 (FGFR2) inhibitor, pemigatinib, was the first approved targeted therapy for patients with locally advanced or metastatic intrahepatic CCA who had FGFR2 gene fusions or rearrangement. More regulatory approvals for matched targeted therapies as second-line or subsequent treatments in advanced CCA followed, including additional drugs that target FGFR2 gene fusion/rearrangement. Recent tumor-agnostic approvals include (but are not limited to) drugs that target mutations/rearrangements in the following genes and are hence applicable to CCA: isocitrate dehydrogenase 1 (IDH1); neurotrophic tropomyosin-receptor kinase (NTRK); the V600E mutation of the BRAF gene (BRAFV600E); and high tumor mutational burden, high microsatellite instability, and gene mismatch repair-deficient (TMB-H/MSI-H/dMMR) tumors. Ongoing trials investigate HER2, RET, and non-BRAFV600E mutations in CCA and improvements in the efficacy and safety of new targeted treatments. This review aims to present the current status of molecularly matched targeted therapy for advanced CCA.

Discovery of a Novel ATP-Competitive MEK Inhibitor DS03090629 that Overcomes Resistance Conferred by BRAF Overexpression in BRAF-Mutated Melanoma

Patients with melanoma with activating BRAF mutations (BRAF V600E/K) initially respond to combination therapy of BRAF and MEK inhibitors. However, their clinical efficacy is limited by acquired resistance, in some cases driven by amplification of the mutant BRAF gene and subsequent reactivation of the MAPK pathway. DS03090629 is a novel and orally available MEK inhibitor that inhibits MEK in an ATP-competitive manner. In both in vitro and in vivo settings, potent inhibition of MEK by DS03090629 or its combination with the BRAF inhibitor dabrafenib was demonstrated in a mutant BRAF-overexpressing melanoma cell line model that exhibited a higher MEK phosphorylation level than the parental cell line and then became resistant to dabrafenib and the MEK inhibitor trametinib. DS03090629 also exhibited superior efficacy against a melanoma cell line-expressing mutant MEK1 protein compared with dabrafenib and trametinib. Biophysical analysis revealed that DS03090629 retained its affinity for the MEK protein regardless of its phosphorylation status, whereas the affinity of trametinib declined when the MEK protein was phosphorylated. These results suggest that DS03090629 may be a novel therapeutic option for patients who acquire resistance to the current BRAF- and MEK-targeting therapies.

Evaluation of a Low-Fat Low-Calorie Meal on the Relative Bioavailability of Trametinib and Dabrafenib: Results From a Randomized, Open-Label, 2-Part Study in Healthy Participants

In this randomized, open-label, 2-part, 2 × 2 crossover, phase 1 study, the effect of a low-fat low-calorie (LFLC) meal on the relative bioavailability of a trametinib 2-mg tablet or dabrafenib 150-mg capsule was evaluated in healthy participants. Trametinib adjusted geometric mean ratios (90%CI) of fed : fasted for area under the concentration-time curve (AUC) from time 0 to the last quantifiable concentration and AUC from time 0 extrapolated to infinity were 0.76 (0.71-0.82) and 0.82 (0.77-0.88), respectively. For dabrafenib, the adjusted geometric mean ratios of AUC from time 0 to the last quantifiable concentration and AUC from time 0 extrapolated to infinity (90%CI) for fed:fasted were 0.85 (0.79-0.91) and 0.86 (0.80-0.92), respectively. Consumption of an LFLC meal delayed trametinib and dabrafenib absorption, with an increase in time to maximum concentration of ≈15 and ≈30 minutes, respectively, compared to the fasted state. These findings indicate that consumption of an LFLC meal reduced the bioavailability and delayed the absorption of trametinib and dabrafenib, supporting current recommendations to administer both drugs in the fasting state; however, an occasional LFLC meal is unlikely to affect the pharmacokinetics of the drugs once steady state is reached and, by consequence, not likely to alter the overall intended efficacy.

RAMP: response-aware multi-task learning with contrastive regularization for cancer drug response prediction

The accurate prediction of cancer drug sensitivity according to the multiomics profiles of individual patients is crucial for precision cancer medicine. However, the development of prediction models has been challenged by the complex crosstalk of input features and the resistance-dominant drug response information contained in public databases. In this study, we propose a novel multidrug response prediction framework, response-aware multitask prediction (RAMP), via a Bayesian neural network and restrict it by soft-supervised contrastive regularization. To utilize network embedding vectors as representation learning features for heterogeneous networks, we harness response-aware negative sampling, which applies cell line-drug response information to the training of network embeddings. RAMP overcomes the prediction accuracy limitation induced by the imbalance of trained response data based on the comprehensive selection and utilization of drug response features. When trained on the Genomics of Drug Sensitivity in Cancer dataset, RAMP achieved an area under the receiver operating characteristic curve > 89%, an area under the precision-recall curve > 59% and an $\textrm{F}_1$ score > 52% and outperformed previously developed methods on both balanced and imbalanced datasets. Furthermore, RAMP predicted many missing drug responses that were not included in the public databases. Our results showed that RAMP will be suitable for the high-throughput prediction of cancer drug sensitivity and will be useful for guiding cancer drug selection processes. The Python implementation for RAMP is available at https://github.com/hvcl/RAMP.

RAS: Circuitry and therapeutic targeting

Cancer has affected the lives of millions worldwide and is truly regarded as a devastating disease process. Despite advanced understanding of the genomic underpinning of cancer development and progression, therapeutic challenges are still persistent. Among all the human cancers, around 33% are attributed to mutations in RAS oncogene, a crucial component of the signaling pathways. With time, our understanding of RAS circuitry has improved and now the fact that it activates several downstream effectors, depending on the type and grades of cancer has been established. The circuitry is controlled via post-transcriptional mechanisms and frequent distortions in these mechanisms lead to important metabolic as well as immunological states that favor cancer cells' growth, survival, plasticity and metastasis. Therefore, understanding RAS circuitry can help researchers/clinicians to develop novel and potent therapeutics that, in turn, can save the lives of patients suffering from RAS-mutant cancers. There are many challenges presented by resistance and the potential strategies with a particular focus on novel combinations for overcoming these, that could move beyond transitory responses in the direction of treatment. Here in this review, we will look at how understanding the circuitry of RAS can be put to use in making strategies for developing therapeutics against RAS- driven malignancies.

Case report: Complete response of an anaplastic thyroid carcinoma patient with NRAS Q61R/BRAF D594N mutations to the triplet of dabrafenib, trametinib and PD-1 antibody

Anaplastic thyroid carcinoma, BRAF non-V600, NRAS, combination immunotherapy and targeted therapy, case report. Anaplastic thyroid carcinoma (ATC) is a rare type of thyroid cancer with a mortality rate near 100%. BRAF V600 and NRAS mutations are the most common drivers of ATC. While patients with BRAF V600-mutated ATC can be treated with BRAF-targeted therapy, there is no effective treatment for ATC driven by NRAS or non-V600 BRAF mutations. For patients with untargetable driver mutations, immunotherapy provides an alternative treatment option. Here, we present a metastatic ATC patient with PD-L1 positive (tumor proportion score of 60%) tumor and NRAS Q61R/BRAF D594N mutations, who progressed on PD-1 antibody sintilimab plus angiogenesis inhibitor anlotinib. The class 3 BRAF mutant D594N is sensitive to the inhibition of MEK inhibitor trametinib, and its oncogenic activity also depends on CRAF, which can be inhibited by BRAF inhibitor dabrafenib. For these reasons, the patient received a salvage treatment regime of dabrafenib, trametinib, and sintilimab, which resulted in a complete pathological response. To our best knowledge, this is the first report of successful treatment of ATC patients with concurrent NRAS/BRAF non-V600 mutations with the combination of immunotherapy and targeted therapy. Further investigation is required to decipher the mechanism by which the combination of dabrafenib/trametinib with PD-1 antibody overcomes initial immunotherapy resistance likely mediated by concurrent BRAF and NRAS mutations.

BRAF and MEK Inhibitors and Their Toxicities: A Meta-Analysis

PURPOSE

This meta-analysis summarizes the incidence of treatment-related adverse events (AE) of BRAFi and MEKi.

METHODS

A systematic search of Medline/PubMed was conducted to identify suitable articles published in English up to 31 December 2021. The primary outcomes were profiles for all-grade and grade 3 or higher treatment-related AEs, and the analysis of single side effects belonging to both categories.

RESULTS

The overall incidence of treatment-related all-grade Aes was 99% for Encorafenib (95% CI: 0.97-1.00) and 97% for Trametinib (95% CI: 0.92-0.99; I² = 66%) and Binimetinib (95% CI: 0.94-0.99; I² = 0%). In combined therapies, the rate was 98% for both Vemurafenib + Cobimetinib (95% CI: 0.96-0.99; I² = 77%) and Encorafenib + Binimetinib (95% CI: 0.96-1.00). Grade 3 or higher adverse events were reported in 69% of cases for Binimetinib (95% CI: 0.50-0.84; I² = 71%), 68% for Encorafenib (95% CI: 0.61-0.74), and 72% for Vemurafenib + Cobimetinib (95% CI: 0.65-0.79; I² = 84%). The most common grade 1-2 AEs were pyrexia (43%) and fatigue (28%) for Dabrafenib + Trametinib and diarrhea for both Vemurafenib + Cobimetinib (52%) and Encorafenib + Binimetinib (34%). The most common AEs of grade 3 or higher were pyrexia, rash, and hypertension for Dabrafenib + Trametinib (6%), rash and hypertension for Encorafenib + Binimetinib (6%), and increased AST and ALT for Vemurafenib + Cobimetinib (10%).

CONCLUSIONS

Our study provides comprehensive data on treatment-related adverse events of BRAFi and MEKi combination therapies, showing related toxicity profiles to offer a helpful tool for clinicians in the choice of therapy.

Predictive biomarkers for response to trametinib in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a leading cause of cancer deaths. Current companion diagnostics use driver mutation sequencing to select patients for molecularly targeted agents (MTA), even though most patients lack actionable mutations. These diagnostics utilize static biomarkers, ignoring real-time tumor cell biology.

OBJECTIVE

Trametinib is FDA-approved in combination with dabrafenib for BRAF V600E-positive NSCLC, however, it has plausible utility beyond these patients. We sought to identify novel biomarkers for maximizing trametinib application.

METHODS

Trametinib responses were evaluated in 12 EGFR/BRAF wild-type (WT) NSCLC cell lines with diverse RAS mutational status. We identified three response categories by colony assay. Trametinib-induced molecular dynamics were studied using immunoassays and apoptosis/necrosis assays, to identify predictive response biomarkers.

RESULTS

p27 accumulation and cyclin D1 downregulation suggested universal cell cycle arrest with trametinib. However, 4 cell lines showed PARP cleavage and 8 showed increased phospho-4E-BP1, suggesting varied cellular outcomes from apoptosis, necrosis, senescence to autophagy. Cleaved PARP, phospho-4E-BP1 and phospho-AKT expression can predict these outcomes.

CONCLUSIONS

Trametinib monotherapy outcome may depend upon cellular context more than oncogenic mutation status. In BRAF WT NSCLC, trametinib may be best suited for combination therapy and dynamic biomarkers could select combinations and predict responses.

Early experience with targeted therapy as a first-line adjuvant treatment for pediatric low-grade glioma

OBJECTIVE

Pediatric low-grade gliomas (pLGGs) frequently exhibit dysregulation of the mitogen-activated protein kinase (MAPK) pathway. Targeted therapies, including mutant BRAF inhibitors (dabrafenib) and MEK inhibitors (trametinib), have shown promise in patients in whom conventional chemotherapy has failed. However, few studies have investigated the use of targeted therapy as a first-line treatment for pLGG. Here, the authors reviewed their institutional experience with using a personalized medicine approach to patients with newly diagnosed pLGGs.

METHODS

All pediatric patients at the authors' institution who had been treated with dabrafenib or trametinib for pLGG without first receiving conventional chemotherapy or radiation were retrospectively reviewed. Demographic, clinical, and radiological data were collected.

RESULTS

Eight patients underwent targeted therapy as a first-line treatment for pLGG. Five patients had a BRAF alteration (1 with a BRAFV600E mutation, 4 with a KIAA1549:BRAF fusion), and 3 patients had an NF1 mutation. One of the 8 patients was initially treated with dabrafenib, and trametinib was added later. Seven patients were initially treated with trametinib; of these, 2 later transitioned to dual therapy, whereas 5 continued with trametinib monotherapy. Six patients (75%) demonstrated a partial response to therapy during their treatment course, whereas stable disease was identified in the remaining 2 patients (25%). One patient experienced mild disease progression after completing a course of trametinib monotherapy, but ultimately stabilized after a period of close observation. Another patient experienced tumor progression while on dabrafenib, but subsequently responded to dual therapy with dabrafenib and trametinib. The most common adverse reactions to targeted therapy were cutaneous toxicity (100%) and diarrhea (50%).

CONCLUSIONS

Targeted therapies have the potential to become a standard treatment option for pLGG due to their favorable toxicity profile and oral route of administration. This case series provides preliminary evidence that targeted therapies can induce an early disease response as a first-line adjuvant treatment; however, large-scale studies are required to assess long-term durability and safety.

In Vitro/In Vivo Translation of Synergistic Combination of MDM2 and MEK Inhibitors in Melanoma Using PBPK/PD Modelling: Part II

The development of in vitro/in vivo translational methods for synergistically acting drug combinations is needed to identify the most effective therapeutic strategies. We performed PBPK/PD modelling for siremadlin, trametinib, and their combination at various dose levels and dosing schedules in an A375 xenografted mouse model (melanoma cells). In this study, we built models based on in vitro ADME and in vivo PK/PD data determined from the literature or estimated by the Simcyp Animal simulator (V21). The developed PBPK/PD models allowed us to account for the interactions between siremadlin and trametinib at PK and PD levels. The interaction at the PK level was described by an interplay between absorption and tumour disposition levels, whereas the PD interaction was based on the in vitro results. This approach allowed us to reasonably estimate the most synergistic and efficacious dosing schedules and dose levels for combinations of siremadlin and trametinib in mice. PBPK/PD modelling is a powerful tool that allows researchers to properly estimate the in vivo efficacy of the anticancer drug combination based on the results of in vitro studies. Such an approach based on in vitro and in vivo extrapolation may help researchers determine the most efficacious dosing strategies and will allow for the extrapolation of animal PBPK/PD models into clinical settings.

The lipid transporter HDLBP promotes hepatocellular carcinoma metastasis through BRAF-dependent epithelial-mesenchymal transition

Tumor metastasis is a major cause of cancer mortality. However, little is known regarding the regulation of abnormal cholesterol metabolism in hepatocellular carcinoma (HCC) metastasis. Here, we show that the expression of high-density lipoprotein binding protein (HDLBP), a lipid transporter, is clinically correlated with tumor metastasis in HCC patients. Moreover, HDLBP was required for cholesterol-induced HCC metastasis. We revealed that knockdown and overexpression of HDLBP significantly inhibited and enhanced, respectively, the metastasis, invasion and epithelial-mesenchymal transition (EMT) of HCC cells in vitro and in vivo. Mechanistically, coimmunoprecipitation and mass spectrometry screening uncovered BRAF as a protein target of HDLBP. HDLBP was found to promote EMT signaling in a BRAF-dependent manner. Furthermore, HDLBP interacts with BRAF and inhibits its ubiquitinated degradation by abrogating BRAF-ITCH interactions. Notably, further studies suggest that dabrafenib exhibited a greater metastasis-suppressive effect in HDLBP knockout HCC than isolated treatment. Overall, our findings imply that cholesterol-induced HDLBP contributes to the metastasis and invasion of HCC through BRAF-dependent EMT signaling and that HDLBP may be applied as a biomarker and therapeutic target for HCC.

Polyglutamate-based nanoconjugates for image-guided surgery and post-operative melanoma metastases prevention

Rationale: Cutaneous melanoma is the most aggressive and deadliest of all skin malignancies. Complete primary tumor removal augmented by advanced imaging tools and effective post-operative treatment is critical in the prevention of tumor recurrence and future metastases formation. Methods: To meet this challenge, we designed novel polymeric imaging and therapeutic systems, implemented in a two-step theranostic approach. Both are composed of the biocompatible and biodegradable poly(α,L-glutamic acid) (PGA) nanocarrier that facilitates extravasation-dependent tumor targeting delivery. The first system is a novel, fluorescent, Turn-ON diagnostic probe evaluated for the precise excision of the primary tumor during image-guided surgery (IGS). The fluorescence activation of the probe occurs via PGA degradation by tumor-overexpressed cathepsins that leads to the separation of closely-packed, quenched FRET pair. This results in the emission of a strong fluorescence signal enabling the delineation of the tumor boundaries. Second, therapeutic step is aimed to prevent metastases formation with minimal side effects and maximal efficacy. To that end, a targeted treatment containing a BRAF (Dabrafenib - mDBF)/MEK (Selumetinib - SLM) inhibitors combined on one polymeric platform (PGA-SLM-mDBF) was evaluated for its anti-metastatic, preventive activity in combination with immune checkpoint inhibitors (ICPi) αPD1 and αCTLA4. Results: IGS in melanoma-bearing mice led to a high tumor-to-background ratio and reduced tumor recurrence in comparison with mice that underwent surgery under white light (23% versus 33%, respectively). Adjuvant therapy with PGA-SLM-mDBF combined with ICPi, was well-tolerated and resulted in prolonged survival and prevention of peritoneal and brain metastases formation in BRAF-mutated melanoma-bearing mice. Conclusions: The results reveal the great clinical potential of our PGA-based nanosystems as a tool for holistic melanoma treatment management.

Low Doses of Celecoxib Might Promote Phenotype Switching in Cutaneous Melanoma Treated with Dabrafenib-Preliminary Study

Background: Cutaneous melanoma is a heterogeneous tumor with a rapidly switching molecular and cellular phenotype. The invasive phenotype switching characterized by MITFlow/AXLhigh predicts early resistance to multiple targeted drugs in melanoma. Celecoxib proved to be a valuable adjuvant in cutaneous melanoma in preclinical studies. Our in vitro study evaluated for the first time whether celecoxib could prevent phenotype switching in two human melanoma cell lines treated with dabrafenib. Methods: All in vitro experiments were carried out on BRAF-V600E-positive A375 and SK-MEL-28 human melanoma cell lines, and subjected to a celecoxib and dabrafenib drug combination for 72 h. Melanoma cells were already in the MITFlow/AXLhigh end of the spectrum. Of main interest was the evaluation of the key proteins expressed in phenotype switching (TGF-β, MITF, AXL, YAP, TAZ), as well as cell death mechanisms correlated with oxidative stress production. Results: Celecoxib significantly enhanced the apoptotic effect of dabrafenib in each melanoma cell line compared to the dabrafenib group (p < 0.0001). Even though celecoxib promoted low MITF expression, this was correlated with high receptor tyrosine kinase AXL levels in A375 and SK-MEL-28 cell lines (p < 0.0001), a positive marker for the phenotype switch to an invasive state. Conclusion: This preliminary study highlighted that celecoxib might promote MITFlow/AXLhigh expression in cutaneous melanoma treated with dabrafenib, facilitating phenotype switching in vitro. Our results need further confirmation, as this finding could represent an important limitation of celecoxib as an antineoplastic drug.

Immunotherapy for the Treatment of Squamous Cell Carcinoma: Potential Benefits and Challenges

Melanoma and nonmelanoma skin cancers (NMSCs) are recognized as among the most common neoplasms, mostly in white people, with an increasing incidence rate. Among the NMSCs, squamous cell carcinoma (SCC) is the most prevalent malignancy known to affect people with a fair complexion who are exposed to extreme ultraviolet radiation (UVR), have a hereditary predisposition, or are immunosuppressed. There are several extrinsic and intrinsic determinants that contribute to the pathophysiology of the SCC. The therapeutic modalities depend on the SCC stages, from actinic keratosis to late-stage multiple metastases. Standard treatments include surgical excision, radiotherapy, and chemotherapy. As SCC represents a favorable tumor microenvironment with high tumor mutational burden, infiltration of immune cells, and expression of immune checkpoints, the SCC tumors are highly responsive to immunotherapies. Until now, there are three checkpoint inhibitors, cemiplimab, pembrolizumab, and nivolumab, that are approved for the treatment of advanced, recurrent, or metastatic SCC patients in the United States. Immunotherapy possesses significant therapeutic benefits for patients with metastatic or locally advanced tumors not eligible for surgery or radiotherapy to avoid the potential toxicity caused by the chemotherapies. Despite the high tolerability and efficiency, the existence of some challenges has been revealed such as, resistance to immunotherapy, less availability of the biomarkers, and difficulty in appropriate patient selection. This review aims to accumulate evidence regarding the genetic alterations related to SCC, the factors that contribute to the potential benefits of immunotherapy, and the challenges to follow this treatment regime.

The Evolution of BRAF Activation in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is the most common subtype of lung cancer, of which approximate 4% had BRAF activation, with an option for targeted therapy. BRAF activation comprises of V600 and non-V600 mutations, fusion, rearrangement, in-frame deletions, insertions, and co-mutations. In addition, BRAF primary activation and secondary activation presents with different biological phenotypes, medical senses and subsequent treatments. BRAF primary activation plays a critical role in proliferation and metastasis as a driver gene of NSCLC, while secondary activation mediates acquired resistance to other targeted therapy, especially for epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI). Treatment options for different activation of BRAF are diverse. Targeted therapy, especially two-drug combination therapy, is an important option. Besides, immune checkpoint inhibitors (ICIs) would be another option since BRAF activation would be a positive biomarker of tumor response of ICIs therapy. To date, no high level evidences support targeted therapy or immunotherapy as prioritized recommendation. After targeted therapy, the evolution of BRAF includes the activation of the upstream, downstream and bypass pathways of BRAF. In this review, therapeutic modalities and post-therapeutic evolutionary pathways of BRAF are discussed, and future research directions are also provided.

Target-Agnostic P-Glycoprotein Assessment Yields Strategies to Evade Efflux, Leading to a BRAF Inhibitor with Intracranial Efficacy

The blood-brain barrier (BBB) presents a major hurdle in the development of central nervous system (CNS) active therapeutics, and expression of the P-glycoprotein (P-gp) efflux transporter at the blood-brain interface further impedes BBB penetrance of most small molecules. Designing efflux liabilities out of compounds can be laborious, and there is currently no generalizable approach to directly transform periphery-limited agents to ones active in the CNS. Here, we describe a target-agnostic, prospective assessment of P-gp efflux using diverse compounds. Our results demonstrate that reducing the molecular size or appending a carboxylic acid in many cases enables evasion of P-gp efflux in cell-based experiments and in mice. These strategies were then applied to transform a periphery-limited ^V600EBRAF inhibitor, dabrafenib, into versions that possess potent and selective anti-cancer activity but now also evade P-gp-mediated efflux. When compared to dabrafenib, the compound developed herein (everafenib) has superior BBB penetrance and superior efficacy in an intracranial mouse model of metastatic melanoma, suggesting it as a lead candidate for the treatment of melanoma metastases to the brain and gliomas with BRAF mutation. More generally, the results described herein suggest the actionability of the trends observed in these target-agnostic efflux studies and provide guidance for the conversion of non-BBB-penetrant drugs into versions that are BBB-penetrant and efficacious.

Overcoming differential tumor penetration of BRAF inhibitors using computationally guided combination therapy

BRAF-targeted kinase inhibitors (KIs) are used to treat malignancies including BRAF-mutant non-small cell lung cancer, colorectal cancer, anaplastic thyroid cancer, and, most prominently, melanoma. However, KI selection criteria in patients remain unclear, as are pharmacokinetic/pharmacodynamic (PK/PD) mechanisms that may limit context-dependent efficacy and differentiate related drugs. To address this issue, we imaged mouse models of BRAF-mutant cancers, fluorescent KI tracers, and unlabeled drug to calibrate in silico spatial PK/PD models. Results indicated that drug lipophilicity, plasma clearance, faster target dissociation, and, in particular, high albumin binding could limit dabrafenib action in visceral metastases compared to other KIs. This correlated with retrospective clinical observations. Computational modeling identified a timed strategy for combining dabrafenib and encorafenib to better sustain BRAF inhibition, which showed enhanced efficacy in mice. This study thus offers principles of spatial drug action that may help guide drug development, KI selection, and combination.

BRAF inhibitors and their immunological effects in malignant melanoma

INTRODUCTION

The treatment of cutaneous melanoma has been revolutionised by the development of small molecule inhibitors targeting the MAPK pathway, including inhibitors of BRAF (BRAFi) and MEK (MEKi), and immune checkpoint blockade antibodies, occurring in tandem. Despite these advances, the 5-year survival rate for patients with advanced melanoma remains only around 50%. Although not designed to alter immune responses within the tumour microenvironment (TME), MAPK pathway inhibitors (MAPKi) exert a range of effects on the host immune compartment which may offer opportunities for therapeutic interventions.

AREAS COVERED

We review the effects of MAPKi especially BRAFi, on the TME, focussing on alterations in inflammatory cytokine secretion, the recruitment of immune cells and their functions, both during response to BRAFi treatment and as resistance develops. We outline potential combinations of MAPKi with established and experimental treatments.

EXPERT OPINION

MAPKi in combination or in sequence with established treatments such as checkpoint inhibitors, anti-angiogenic agents, or new therapies such as adoptive cell therapies, may augment their immunological effects, reverse tumour-associated immune suppression and offer the prospect of longer-lived clinical responses. Refining therapeutic tools at our disposal and embracing "old friends" in the melanoma treatment arsenal, alongside new target identification, may improve the chances of therapeutic success.

Current treatment strategies and future perspectives for gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that originate from the gastrointestinal tract, mostly from the stomach. GISTs are derived from the myenteric interstitial cells of Cajal and are caused by several mutations in the c-kit and platelet-derived growth factor receptor genes. Clinically, GISTs are detected by endoscopic and imaging findings and are diagnosed by immunostaining. Surgery is the first line of treatment, and if the tumor is relatively small, minimally invasive surgery such as laparoscopy is performed. In recent years, neoadjuvant therapy has been administered to patients with GISTs that are suspected of having a large size or infiltration to other organs. Postoperative adjuvant imatinib is the standard therapy for high-risk GISTs. It is important to assess the risk of recurrence after GIST resection. However, the effect of tyrosine kinase inhibitor use will vary by the mutation of c-kit genes and the site of mutation. Furthermore, information regarding gene mutation is indispensable when considering the treatment policy for recurrent GISTs. This article reviews the clinicopathological characteristics of GISTs along with the minimally invasive and multidisciplinary treatment options available for these tumors. The future perspectives for diagnostic and treatment approaches for these tumors have also been discussed.

Potential of Withaferin-A, Withanone and Caffeic Acid Phenethyl ester as ATP-competitive inhibitors of BRAF: A bioinformatics study

Serine/threonine-protein kinase B-raf (BRAF) plays a significant role in regulating cell division and proliferation through MAPK/ERK pathway. The constitutive expression of wild-type BRAF (BRAF^WT) and its mutant forms, especially V600E (BRAF^V600E), has been linked to multiple cancers. Various synthetic drugs have been approved and are in clinical trials, but most of them are reported to become ineffective within a short duration. Therefore, combinational therapy involving multiple drugs are often recruited for cancer treatment. However, they lead to toxicity and adverse side effects. In this computational study, we have investigated three natural compounds, namely Withaferin-A (Wi-A), Withanone (Wi-N) and Caffeic Acid Phenethyl ester (CAPE) for anti-BRAF^WT and anti-BRAF^V600E activity. We found that these compounds could bind stably at ATP-binding site in both BRAF^WT and BRAF^V600E proteins. In-depth analysis revealed that these compounds maintained the active conformation of wild-type BRAF protein by inducing αC-helix-In, DFG-In, extended activation segment and well-aligned R-spine residues similar to already known drugs Vemurafenib (VEM), BGB283 and Ponatinib. In terms of binding energy, among the natural compounds, CAPE showed better affinity towards both wild-type and V600E mutant proteins than the other two compounds. These data suggested that CAPE, Wi-A and Wi-N have potential to block constitutive autophosphorylation of BRAF and hence warrant in vitro and in vivo experimental validation.

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Out of all the human cancers approximately 8% involve BRAF mutations.

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The 40–50% of the commercialized drugs in the market are from the natural sources or inspired by it.

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Three natural compounds Withaferin-A , Withanone and Caffeic acid phenethyl ester (CAPE) have been studied against BRAF.

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CAPE binds with higher binding affinity with BRAF wild type protein and BRAF V600E mutant protein than other natural compounds.

Implications of glutathione-S transferase P1 in MAPK signaling as a CRAF chaperone: In memory of Dr. Irving Listowsky

Glutathione-S transferase P1 (GSTP1) is one of the glutathione-S transferase isozymes that belong to a family of phase II metabolic isozymes. The unique feature of GSTP1 compared with other GST isozymes is its relatively high expression in malignant tissues. Thus, clinically, GSTP1 serves as a tumor marker and as a refractory factor against certain types of anticancer drugs through its primary function as a detoxifying enzyme. Additionally, recent studies have identified a chaperone activity of GSTP1 involved in the regulation the function of various intracellular proteins, including factors of the growth signaling pathway. In this review, we will first describe the function of GSTP1 and then extend the details onto its role in the mitogen-activated protein kinase signal pathway, referring to the results of our recent study that proposed a novel autocrine signal loop formed by the CRAF/GSTP1 complex in mutated KRAS and BRAF cancers. Finally, the possibilities of new therapeutic approaches for these cancers by targeting this complex will be discussed.