Selumetinib (AZD6244; ARRY-142886) in the treatment of metastatic melanoma

Selumetinib - a potential small molecule inhibitor for osteoarthritis treatment

Objectives: Osteoarthritis (OA) is a common disease that mainly manifests as inflammation and destruction of cartilage and subchondral bone. Recently, necroptosis has been reported to play an important role in the development of OA. Selumetinib displays a contrasting expression pattern to necroptosis-related proteins. The present study aimed to investigate the potential therapeutic effects of selumetinib in OA process.

Methods:In vitro experiments, interleukin-1β (IL-1β) was used to induce necroptosis of chondrocytes. We used high-density cell culture, Western Blot and PT-PCR to observe the effect of different concentrations of selumetinib on the extracellular matrix of cartilage. Afterwards, we visualized the effect of selumetinib on osteoclast formation by TRAP staining and F-actin rings. In vivo experiment, we induced experimental osteoarthritis in mice by surgically destabilizing the medial meniscus (DMM) while administering different concentrations of selumetinib intraperitoneally.

Results: Selumetinib promoted cartilage matrix synthesis and inhibited matrix decomposition. We found that selumetinib exerted a protective function by inhibiting the activation of RIP1/RIP3/MLKL signaling pathways in chondrocytes. Selumetinib also inhibited the activation of RANKL-induced NF-κB and MAPK signaling pathways in BMMs, thereby interfering with the expression of osteoclast marker genes. In the DMM-induced OA model, a postsurgical injection of selumetinib inhibited cartilage destruction and lessened the formation of TRAP-positive osteoclasts in subchondral bone.

Conclusion: Selumetinib can protect chondrocytes by regulating necroptosis to prevent the progression of OA and reduce osteoclast formation. In summary, our findings suggest that selumetinib has potential as a therapeutic agent for OA.

Proteomic Changes in the Monolayer and Spheroid Melanoma Cell Models of Acquired Resistance to BRAF and MEK1/2 Inhibitors

Extracellular signal-regulated kinase-1/2 (ERK1/2) pathway inhibitors are important therapies for treating many cancers. However, acquired resistance to most protein kinase inhibitors limits their ability to provide durable responses. Approximately 50% of malignant melanomas contain activating mutations in BRAF, which promotes cancer cell survival through the direct phosphorylation of the mitogen-activated protein kinase MAPK/ERK 1/2 (MEK1/2) and the activation of ERK1/2. Although the combination treatment with BRAF and MEK1/2 inhibitors is a recommended approach to treat melanoma, the development of drug resistance remains a barrier to achieving long-term patient benefits. Few studies have compared the global proteomic changes in BRAF/MEK1/2 inhibitor-resistant melanoma cells under different growth conditions. The current study uses high-resolution label-free mass spectrometry to compare relative protein changes in BRAF/MEK1/2 inhibitor-resistant A375 melanoma cells grown as monolayers or spheroids. While approximately 66% of proteins identified were common in the monolayer and spheroid cultures, only 6.2 or 3.6% of proteins that significantly increased or decreased, respectively, were common between the drug-resistant monolayer and spheroid cells. Drug-resistant monolayers showed upregulation of ERK-independent signaling pathways, whereas drug-resistant spheroids showed primarily elevated catabolic metabolism to support oxidative phosphorylation. These studies highlight the similarities and differences between monolayer and spheroid cell models in identifying actionable targets to overcome drug resistance.

Molecular Markers and Targets in Melanoma

Melanoma develops as a result of several genetic alterations, with UV radiation often acting as a mutagenic risk factor. Deep knowledge of the molecular signaling pathways of different types of melanoma allows better characterization and provides tools for the development of therapies based on the intervention of signals promoted by these cascades. The latest World Health Organization classification acknowledged the specific genetic drivers leading to melanoma and classifies melanocytic lesions into nine distinct categories according to the associate cumulative sun damage (CSD), which correlates with the molecular alterations of tumors. The largest groups are melanomas associated with low-CSD or superficial spreading melanomas, characterized by frequent presentation of the BRAFV600 mutation. High-CSD melanomas include lentigo maligna type and desmoplastic melanomas, which often have a high mutation burden and can harbor NRAS, BRAFnon-V600E, or NF1 mutations. Non-CSD-associated melanomas encompass acral and mucosal melanomas that usually do not show BRAF, NRAS, or NF1 mutations (triple wild-type), but in a subset may have KIT or SF3B1 mutations. To improve survival, these driver alterations can be treated with targeted therapy achieving significant antitumor activity. In recent years, relevant improvement in the prognosis and survival of patients with melanoma has been achieved, since the introduction of BRAF/MEK tyrosine kinase inhibitors and immune checkpoint inhibitors. In this review, we describe the current knowledge of molecular pathways and discuss current and potential therapeutic targets in melanoma, focusing on their clinical relevance of development.

Phase Ib Results of the Rational Combination of Selumetinib and Cyclosporin A in Advanced Solid Tumors with an Expansion Cohort in Metastatic Colorectal Cancer

MEK inhibition is of interest in cancer drug development, but clinical activity in metastatic colorectal cancer (mCRC) has been limited. Preclinical studies demonstrated Wnt pathway overexpression in KRAS-mutant cell lines resistant to the MEK inhibitor, selumetinib. The combination of selumetinib and cyclosporin A, a noncanonical Wnt pathway modulator, demonstrated antitumor activity in mCRC patient-derived xenografts. To translate these results, we conducted a NCI Cancer Therapy Evaluation Program-approved multicenter phase I/IB trial (NCT02188264) of the combination of selumetinib and cyclosporin A. Patients with advanced solid malignancies were treated with the combination of oral selumetinib and cyclosporin A in the dose escalation phase, followed by an expansion cohort of irinotecan and oxaliplatin-refractory mCRC. The expansion cohort utilized a single-agent selumetinib "run-in" to evaluate FZD2 biomarker upregulation and KRAS-WT and KRAS-MT stratification to identify any potential predictors of efficacy. Twenty and 19 patients were enrolled in dose escalation and expansion phases, respectively. The most common adverse events and grade 3/4 toxicities were rash, hypertension, and edema. Three dose-limiting toxicities (grade 3 hypertension, rash, and increased creatinine) were reported. The MTD was selumetinib 75 mg twice daily and cyclosporin A 2 mg/kg twice daily on a 28-day cycle. KRAS stratification did not identify any differences in response between KRAS-WT and KRAS-MT cancers. Two partial responses, 18 stable disease, and 10 progressive disease responses were observed. Combination selumetinib and cyclosporin A is well tolerated, with evidence of activity in mCRC. Future strategies for concept development include identifying better predictors of efficacy and improved Wnt pathway modulation.Significance: These findings translate preclinical studies combining selumetinib and cyclosporin into a phase I first-in-human clinical trial of such a combination in patients with advanced solid malignancies. Cancer Res; 78(18); 5398-407. ©2018 AACR.

The anti-rheumatic drug, leflunomide, synergizes with MEK inhibition to suppress melanoma growth

Cutaneous melanoma, which develops from the pigment producing cells called melanocytes, is the most deadly form of skin cancer. Unlike the majority of other cancers, the incidence rates of melanoma are still on the rise and the treatment options currently available are being hindered by resistance, limited response rates and adverse toxicity. We have previously shown that an FDA approved drug leflunomide, used for rheumatoid arthritis (RA), also holds potential therapeutic value in treating melanoma especially if used in combination with the mutant BRAF inhibitor, vemurafenib. We have further characterized the function of leflunomide and show that the drug reduces the number of viable cells in both wild-type and BRAF^V600E mutant melanoma cell lines. Further experiments have revealed leflunomide reduces cell proliferation and causes cells to arrest in G1 of the cell cycle. Cell death assays show leflunomide causes apoptosis at treatment concentrations of 25 and 50 µM. To determine if leflunomide could be used combinatorialy with other anti-melanoma drugs, it was tested in combination with the MEK inhibitor, selumetinib. This combination showed a synergistic effect in the cell lines tested. This drug combination led to an enhanced decrease in tumor size when tested in vivo compared to either drug alone, demonstrating its potential as a novel combinatorial therapy for melanoma.

Targeting MAPK pathway in melanoma therapy

New drugs targeting the mitogen-activated protein kinase (MAPK) pathway have generated striking clinical response in melanoma therapy. From the discovery of BRAF mutation in melanoma in 2002, to the approval of first BRAF inhibitor vemurafenib for melanoma treatment by the US Food and Drug Administration in 2011, therapies targeting the MAPK pathway have been proven effective in less than a decade. The success of vemurafenib stimulated more intensive investigation of the molecular mechanisms of melanoma pathogenesis and development of new treatment strategies targeting specific molecules in MAPK pathway. Although selective BRAF inhibitors and MEK inhibitors demonstrated improved overall survival of metastatic melanoma patients, limited duration or development of resistance to BRAF inhibitors have been reported. Patients with metastatic melanoma still face very poor prognosis and lack of clarified therapies. Studies and multiple clinical trials on more potent and selective small molecule inhibitory compounds to further improve the clinical effects and overcome drug resistance are underway. In this review, we analyzed the therapeutic potentials of each member of the MAPK signaling pathway, summarized important MAPK-inhibiting drugs, and discussed the promising combination treatment targeting multiple targets in melanoma therapy, which may overcome the drawbacks of current drugs treatment.

Complement pathway is frequently altered in endometriosis and endometriosis-associated ovarian cancer

PURPOSE

Mechanisms of immune dysregulation associated with advanced tumors are relatively well understood. Much less is known about the role of immune effectors against cancer precursor lesions. Endometrioid and clear-cell ovarian tumors partly derive from endometriosis, a commonly diagnosed chronic inflammatory disease. We performed here a comprehensive immune gene expression analysis of pelvic inflammation in endometriosis and endometriosis-associated ovarian cancer (EAOC).

EXPERIMENTAL DESIGN

RNA was extracted from 120 paraffin tissue blocks comprising of normal endometrium (n = 32), benign endometriosis (n = 30), atypical endometriosis (n = 15), and EAOC (n = 43). Serous tumors (n = 15) were included as nonendometriosis-associated controls. The immune microenvironment was profiled using Nanostring and the nCounter GX Human Immunology Kit, comprising probes for a total of 511 immune genes.

RESULTS

One third of the patients with endometriosis revealed a tumor-like inflammation profile, suggesting that cancer-like immune signatures may develop earlier, in patients classified as clinically benign. Gene expression analyses revealed the complement pathway as most prominently involved in both endometriosis and EAOC. Complement proteins are abundantly present in epithelial cells in both benign and malignant lesions. Mechanistic studies in ovarian surface epithelial cells from mice with conditional (Cre-loxP) mutations show intrinsic production of complement in epithelia and demonstrate an early link between Kras- and Pten-driven pathways and complement upregulation. Downregulation of complement in these cells interferes with cell proliferation.

CONCLUSIONS

These findings reveal new characteristics of inflammation in precursor lesions and point to previously unknown roles of complement in endometriosis and EAOC.

MiR-92a mediates AZD6244 induced apoptosis and G1-phase arrest of lymphoma cells by targeting Bim

AZD6244, an ATP-uncompetitive inhibitor of mitogen-activated protein kinase 1/2 (MEK1/2), has shown activity in several malignant tumours. However, whether AZD6244 has a function in lymphoma cells is not known. We report that AZD6244 treatment represses the growth of Raji and MOLT4 cells by inducing apoptosis and G1-phase arrest. Using miRNAs array and quantitative RT-PCR, miR-92a was downregulated byAZD6244 treatment through the ERK1/2-AP1 signalling pathway. Overexpression of miR-92a abrogated AZD6244-induced apoptosis and G1-phase arrest, indicating that it is involved in the cytotoxicity of AZD6244 in lymphoma cells. A luciferase reporter assay showed that miR-92a directly targetsthe 3'-UTRs of Bim. Overexpression of miR-92a mimics downregulated Bim mRNA and protein expression level, indicating that miR-92a negatively regulates its expression at both levels. Silencing Bim decreases AZD6244-induced apoptosis and G1-phase arrest, suggesting that Bim contributes to the growth arrest. Thus, miR-92a mediates AZD6244-induced cytotoxicity of lymphoma cells by targeting Bim. Downregulation of miR-92a by AZD6244 is mediated by the ERK1/2-AP1 signalling pathway.

Genomewide RNAi screen identifies protein kinase Cb and new members of mitogen-activated protein kinase pathway as regulators of melanoma cell growth and metastasis

A large-scale RNAi screen was performed for eight different melanoma cell lines using a pooled whole-genome lentiviral shRNA library. shRNAs affecting proliferation of transduced melanoma cells were negatively selected during 10 days of culture. Overall, 617 shRNAs were identified by microarray hybridization. Pathway analyses identified mitogen-activated protein kinase (MAPK) pathway members such as ERK1/2, JNK1/2 and MAP3K7 and protein kinase C β (PKCβ) as candidate genes. Knockdown of PKCβ most consistently reduced cellular proliferation, colony formation and migratory capacity of melanoma cells and was selected for further validation. PKCβ showed enhanced expression in human primary melanomas and distant metastases as compared with benign melanocytic nevi. Moreover, treatment of melanoma cells with PKCβ-specific inhibitor enzastaurin reduced melanoma cell growth but had only small effects on benign fibroblasts. Finally, PKCβ-shRNA significantly reduced lung colonization capacity of stably transduced melanoma cells in mice. Taken together, this study identified new candidate genes for melanoma cell growth and proliferation. PKCβ seems to play an important role in these processes and might serve as a new target for the treatment of metastatic melanoma.

Detecting mechanisms of acquired BRAF inhibitor resistance in melanoma

(V600)BRAF mutation was identified as an ideal target for clinical therapy due to its indispensable roles in supporting melanoma initiation and progression. Despite the fact that BRAF inhibitors (BRAFi) can elicit anti-tumor responses in the majority of treated patients and confer overall survival benefits, acquired drug resistance is a formidable obstacle to long-term management of the disease. Several aberrant events including RTK upregulation, NRAS mutation, mutant BRAF amplification or alternative splicing, and MEK mutation have been reported as acquired BRAFi resistance mechanisms. Clinially, detection of these resistance mechanisms help understand drug response patterns and help guide combinatorial therapeutic strategies. Therefore, quick and accurate diagnosis of the resistant mechanisms in tumor biopsies has become an important starting point for personalized therapy. In this chapter, we review the major acquired BRAFi resistance mechanisms, highlight their therapeutic implications, and provide the diagnostic methods from clinical samples.

Oncogenes in melanoma: an update

Melanoma is a highly aggressive tumour with poor prognosis in the metastatic stage. BRAF, NRAS, and KIT are three well-known oncogenes involved in melanoma pathogenesis. Targeting of mutated BRAF kinase has recently been shown to significantly improve overall survival of metastatic melanoma patients, underscoring the particular role of this oncogene in melanoma biology. However, recurrences regularly occur within several months, which supposedly involve further oncogenes. Moreover, oncogenic driver mutations have not been described for up to 30% of all melanomas. In order to obtain a more complete picture of the mutational landscape of melanoma, more recent studies used high-throughput DNA sequencing technologies. A number of new oncogene candidates such as MAPK1/2, ERBB4, GRIN2A, GRM3, RAC1, and PREX2 were identified. Their particular role in melanoma biology is currently under investigation. Evidence for the functional relevance of some of these new oncogene candidates has been provided in in vitro and in vivo experiments. However, these findings await further validation in clinical studies. This review provides an overview on well-known melanoma oncogenes and new oncogene candidates, based on recent high-throughput sequencing studies. The list of genes discussed herein is of course not complete but highlights some of the most significant of recent findings in this area. The new candidates may support more individualized treatment approaches for metastatic melanoma patients in the future.

Loss of PI(4,5)P2 5-Phosphatase A Contributes to Resistance of Human Melanoma Cells to RAF/MEK Inhibitors

Past studies have shown that the inositol polyphosphate 5-phosphatase, phosphatidylinositol 4,5-bisphosphate 5-phosphatase (PIB5PA), is commonly downregulated or lost in melanomas, which contributes to elevated activation of phosphatidylinositol 3-kinase (PI3K)/Akt in melanoma cells. In this report, we provide evidence that PIB5PA deficiency plays a role in resistance of melanoma cells to RAF/mitogen-activated protein kinase kinase (MEK) inhibitors. Ectopic expression of PIB5PA enhanced apoptosis induced by the RAF inhibitor PLX4720 in BRAF(V600E) and by the MEK inhibitor U0126 in both BRAF(V600E) and wild-type BRAF melanoma cells. This was due to inhibition of PI3K/Akt, as co-introduction of an active form of Akt (myr-Akt) abolished the effect of overexpression of PIB5PA on apoptosis induced by PLX4720 or U0126. While overexpression of PIB5PA triggered activation of Bad and down-regulation of Mcl-1, knockdown of Bad or overexpression of Mcl-1 recapitulated, at least in part, the effect of myr-Akt, suggesting that regulation of Bad and Mcl-1 is involved in PIB5PA-mediated sensitization of melanoma cells to the inhibitors. The role of PIB5PA deficiency in BRAF inhibitor resistance was confirmed by knockdown of PIB5PA, which led to increased growth of BRAF(V600E) melanoma cells selected for resistance to PLX4720. Consistent with its role in vitro, overexpression of PIB5PA and the MEK inhibitor selumetinib cooperatively inhibited melanoma tumor growth in a xenograft model. Taken together, these results identify loss of PIB5PA as a novel resistance mechanism of melanoma to RAF/MEK inhibitors and suggest that restoration of PIB5PA may be a useful strategy to improve the therapeutic efficacy of the inhibitors in the treatment of melanoma.

Dermatologic toxicities to targeted cancer therapy: shared clinical and histologic adverse skin reactions

BACKGROUND

Dermatologic toxicities (DT) to targeted cancer therapy may present as inflammatory dermatoses, keratoses, and as benign and malignant squamous proliferations.

METHODS

Published reports of DT with cancer therapy with epidermal growth factor receptor (EGFR), tyrosine kinase (TK), MEK, PI3K, AKT, and BRAF inhibitors were reviewed.

RESULTS

DT associated with targeted cancer therapy demonstrated similar reactions and may be grouped as (i) DT as cutaneous inflammation, and (ii) DT as cutaneous epithelial proliferation. EGFR inhibitor, cetuximab, and MEK inhibitors, selumetinib and trametinib, demonstrated papulopustular rash with a suppurative folliculitis in 83%, 93%, and 80% of the patients on therapy, respectively. Common DT with EGFR inhibitors erlotinib and tyrosine kinase inhibitor sorafenib were hand-foot skin reactions in 30-60% of patients on therapy. PI3K inhibitor BKM-120 and AKT inhibitor MK2206 produced maculopapular eruptions seen as dermal hypersensitivity reaction on the skin biopsy. RAF inhibitors vemurafenib and sorafenib were associated with a variety of cutaneous epithelial proliferations (keratosis pilaris, seborrheic keratosis, verruca vulgaris, actinic keratosis, keratoacanthoma, and squamous cell carcinoma.

CONCLUSION

Various anticancer agents may target similar cellular compounds and/or cell signaling pathways thus share similar clinical and histologic features of DT. The knowledge of the overlap of DT with different types of targeted cancer therapy will assist in evaluation of cutaneous reactions.

Robustness of signal transduction pathways

Signal transduction pathways transduce information about the outside of the cell to the nucleus, regulating gene expression and cell fate. To reliably inform the cell about its surroundings, information transfer has to be robust against typical perturbation that a cell experiences. Robustness of several mammalian signaling pathways has been studied recently by quantitative experimentation and using mathematical modeling. Here, we review these studies, and describe the emerging concepts of robustness and the underlying mechanisms.

p42/p44 MAPK-mediated Stat3Ser727 phosphorylation is required for progestin-induced full activation of Stat3 and breast cancer growth

Stat3 is a signaling node for multiple oncogenic pathways and is therefore frequently active in breast cancer. As experimental and clinical evidence reveals that progestins are key players in controlling mammary gland tumorigenesis, we studied Stat3 participation in this event. We have previously shown that progestins induce Stat3Tyr705 phosphorylation and its transcriptional activation in breast cancer cells. In this study, we demonstrate that progestins also induce Stat3 phosphorylation at Ser727 residue, which occurs via activation of c-Src/p42/p44 MAPK pathways in murine progestin-dependent C4HD cells and in T-47D cells. Expression of a Stat3S727A vector, which carries a serine-to-alanine substitution at codon 727, shows that Stat3Ser727 phosphorylation is required for full transcriptional activation of cyclin D1 gene expression by progestins and for in vivo Stat3 recruitment on cyclin D1 promoter. Transfection of Stat3S727A in murine and human breast cancer cells abolished progestin-induced in vitro and in vivo growth. Moreover, we found a positive correlation between progesterone receptor expression and nuclear localization of Stat3Ser727 phosphorylation in breast cancer biopsies. These data highlight Stat3 phosphorylation in Ser727 residue as a nongenomic action by progestins, necessary to promote breast cancer growth.

High-throughput sequencing of the melanoma genome

Next-generation sequencing technologies are now common for whole-genome, whole-exome and whole-transcriptome sequencing (RNA-seq) of tumors to identify point mutations, structural or copy number alterations and changes in gene expression. A substantial number of studies have already been performed for melanoma. One study analysed eight melanoma cell lines with RNA-Seq technology and identified 11 novel melanoma gene fusions. Whole-exome sequencing of seven melanoma cell lines identified overlapping gain of function mutations in MAP2K1 (MEK1) and MAP2K2 (MEK2) genes. Integrative sequencing of cutaneous melanoma metastases using different sequencing platforms revealed a new somatic point mutation in HRAS and a structural rearrangement affecting CDKN2C (a CDK4 inhibitor). These latter sequencing-based discoveries may be used to motivate the inclusion of the affected patients into clinical trials with specific signalling pathway inhibitors. Taken together, we are at the beginning of an era with new sequencing technologies providing a more comprehensive view of cancer mutational landscapes and hereby a better understanding of their pathogenesis. This will also open interesting perspectives for new treatment approaches and clinical trial designs.

Novel drugs targeting the epidermal growth factor receptor and its downstream pathways in the treatment of colorectal cancer: a systematic review

Colorectal cancer is the second most common malignancy among men and women in the United States, and the 5-year survival rate remains poor despite recent advances in chemotherapy and targeted agents. The mainstay of therapy for advanced disease remains the cytotoxic chemotherapy including 5-FU, irinotecan, and oxaliplatin. The USFDA approval and introduction of targeted therapies, including cetuximab and panitumumab (monoclonal antibodies targeting the epidermal growth factor receptor (EGFR)) and bevacizumab (monoclonal antibody targeting the vascular epithelial growth factor (VEGF)), has improved the median survival of patients with metastatic colorectal cancer to around 24 months. Clearly, better and more efficacious drugs are needed, and target-specific agents remain the future of cancer treatment. On this front, rapid advances are being made, which are likely to change the future of the management of metastatic colorectal cancer. However, absence of specific biomarkers for the use of targeted agents, in the subset of population who will benefit from the treatment, remains a major drawback. In this paper, we review agents that are in phases 1 and 2 clinical development, specifically targeting the EGFR and its subsequent downstream pathways.