A phase 1 dose-escalation and expansion study of binimetinib (MEK162), a potent and selective oral MEK1/2 inhibitor

Up-and-Coming Experimental Drug Options for Metastatic Colorectal Cancer

Colorectal cancer is one of the top causes of cancer and cancer-related deaths worldwide. The prognosis of metastatic colorectal cancer is poor and treatment options are limited. Many patients will run out of treatment options before they become medically unfit for therapy. As such, there is a need to expand upon the current understanding of disease biology as well as drug resistance mechanisms in order to create new approaches for therapy. In this review article, we will discuss the mechanistic rationale and clinical data for new drugs and therapeutic combinations under development for metastatic colorectal cancer.

Selective Oral MEK1/2 Inhibitor Pimasertib: A Phase I Trial in Patients with Advanced Solid Tumors

BACKGROUND

The Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (Ras/Raf/MEK/ERK) signaling cascade is frequently constitutively activated in human cancers. Pimasertib is a selective and potent adenosine triphosphate non-competitive MEK1/2 inhibitor.

OBJECTIVE

Our objectives were to describe the results of a phase I, first-in-human, dose-escalation trial of pimasertib that investigated the maximum tolerated dose, recommended phase II dose, and safety, as well as other endpoints.

PATIENTS AND METHODS

Four dosing schedules of pimasertib (once daily [qd], 5 days on, 2 days off; qd, 15 days on, 6 days off; continuous qd; continuous twice daily [bid]) were evaluated in patients with advanced solid tumors. Each treatment cycle lasted 21 days. The primary objective was to determine the maximum tolerated dose based on dose-limiting toxicities (DLTs) evaluated during cycle 1, and the recommended phase II dose (RP2D). Secondary objectives included safety, pharmacokinetics, pharmacodynamics, and antitumor activity.

RESULTS

Overall, 180 patients received pimasertib (dose range 1-255 mg/day). DLTs were mainly observed at doses ≥ 120 mg/day and included skin rash/acneiform dermatitis and ocular events, such as serous retinal detachment. The most common drug-related adverse events were consistent with class effects, including diarrhea, skin disorders, ocular disorders, asthenia/fatigue, and peripheral edema. The median time to maximum pimasertib concentration was 1.5 h across dosing schedules, and the apparent terminal half-life was 5 h across qd dosing schedules. Pimasertib decreased ERK phosphorylation within 2 h of administration, which was maintained for up to 8 h at higher doses and prolonged with bid dosing.

CONCLUSIONS

Based on the safety profile and efficacy signals, a continuous bid regimen was the preferred dosing schedule and the RP2D was defined as 60 mg bid.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00982865.

Evaluation of the RAS signaling network in response to MEK inhibition using organoids derived from a familial adenomatous polyposis patient

RAS signaling is a promising target for colorectal cancer (CRC) therapy, and a variety of selective inhibitors have been developed. However, their use has often failed to demonstrate a significant benefit in CRC patients. Here, we used patient-derived organoids (PDOs) derived from a familial adenomatous polyposis (FAP) patient to analyze the response to chemotherapeutic agents targeting EGFR, BRAF and MEK. We found that PDOs carrying KRAS mutations were resistant to MEK inhibition, while those harboring the BRAF class 3 mutation were hypersensitive. We used a systematic approach to examine the phosphorylation of RAS effectors using reverse-phase protein array (RPPA) and found increased phosphorylation of MEK induced by binimetinib. A high basal level of ERK phosphorylation and its rebound activation after MEK inhibition were detected in KRAS-mutant PDOs. Notably, the phosphorylation of EGFR and AKT was more closely correlated with that of MEK than that of ERK. Transcriptome analysis identified MYC-mediated transcription and IFN signaling as significantly correlated gene sets in MEK inhibition. Our experiments demonstrated that RPPA analysis of PDOs, in combination with the genome and transcriptome, is a useful preclinical research platform to understand RAS signaling and provides clues for the development of chemotherapeutic strategies.

OCULAR ADVERSE EVENTS ASSOCIATED WITH MEK INHIBITORS

PURPOSE

Mitogen-activates protein kinase (MAPK) inhibitors, particularly MEK inhibitors, have shifted the treatment paradigm for metastatic BRAF-mutant cutaneous melanoma; however, oncologists, ophthalmologists, and patients have noticed different toxicities of variable importance. This review aims to provide an update of the ocular adverse events (OAEs), especially retinal toxicity, associated with the use of MEK inhibitors.

METHODS

We conducted a scientific literature search using the PubMed database up to July 2018 with the terms "MEK inhibitors" with a "review" filter and "MEK inhibitors" with a "clinical trials" filter. Phase I-III experimental studies and reviews were selected. Current principles and techniques for diagnosing and managing MEK inhibitor retinopathy and other OAEs are discussed.

RESULTS

In patients treated with MEK inhibitors, including asymptomatic patients, OAEs occur with an incidence of up to 90%. Mild to severe ophthalmic toxicities are described, including visual disturbances, a 2-line decrease in Snellen visual acuity, dry eye symptoms, ocular adnexal abnormalities, visual field defects, panuveitis, and retinal toxicities, such as different degrees of MEK-associated retinopathy, vascular injury, and retinal vein occlusion.

CONCLUSION

MEK inhibitors can lead to different degrees of retinal, uveal, and adnexal OAE, causing visual disturbances or discomfort. One of the most relevant OAE of MEK therapy is MEK inhibitor-associated retinopathy (MEKAR), which is usually mild, self-limited, and may subside after continuous use of the drug for weeks or months, or discontinuation, thereby restoring the normal visual function of the retina, with some exceptions. Ocular adverse events are often associated with other systemic adverse effects that can modify the dosage of treatment, so the communication with the oncologist is fundamental.

Encorafenib, binimetinib and cetuximab combined therapy for patients with BRAFV600E mutant metastatic colorectal cancer

Approximately 10-15% of colorectal cancers (CRCs) harbor an activating BRAF mutation, leading to tumor growth promotion by activation of the mitogen-activated protein kinases pathway. BRAFV600E mutations are prognostic for treatment failure after first-line systemic therapy in the metastatic setting. In contrast to the efficacy of combined BRAF and MEK inhibition in melanoma, BRAFV600E mutant CRC is intrinsically unresponsive due to upregulation of HER/EGFR. However, combining the EGFR inhibitor cetuximab, the BRAF inhibitor encorafenib and the MEK inhibitor binimetinib improves overall survival. This review discusses the current treatment field for patients with BRAFV600E mutant metastatic CRC and summarizes the pharmacology, efficacy and safety of the novel doublet and triplet therapies consisting of encorafenib and cetuximab with or without binimetinib.

Systemic treatment options for advanced biliary tract carcinoma

Advanced biliary tract cancers (BTC) include a diverse collection of rare and heterogenous tumors with poor prognosis. The combination of gemcitabine and cisplatin is the established first-line therapy for advanced BTC. There are no accepted standard treatments in the second line setting, though there are several ongoing clinical trials that implement chemotherapy as a therapeutic strategy. The understanding of the molecular landscape of BTC has offered hope of targeted therapies to the identified actionable genomic aberrations, such as FGFR2 gene fusions, mutations of IDH1/2, HER2, BRAC1/2 and BRAF. Pembigatinib has become the first approved targeted therapy for BTC with FGFR2 fusion or other rearrangements. Recent immunotherapy has opened new therapy avenues in BTC with pembrolizumab approved for either microsatellite instability high (MSI-H) or DNA mismatch repair deficient (dMMR) advanced solid tumors, including BTC. The combination of immunotherapy with other modalities is currently being evaluated in different clinical trials, since single agent immunotherapy appears to provide modest benefits in advanced BTC. In this review, we summarize the current status of treatment options, including systemic chemotherapy, targeted therapy, immunotherapy, and various combinations in advanced BTC.

ERK phosphorylation as a marker of RAS activity and its prognostic value in non-small cell lung cancer

BACKGROUND

Deregulated signal transduction pathways play a key role in development, progression and therapeutic resistance of non-small cell lung cancers (NSCLC). The purpose of this study is to assess the downstream markers of two well-characterized pathways and to correlate them with clinical outcome.

DESIGN

670 patients with metastatic NSCLC were prospectively enrolled in a comprehensive biomarker profiling program at a single center from 2012 to 2016. Phosphorylation of extracellular signal-regulated kinase (p-ERK), and protein kinase B (p-AKT) was assessed by standardized immunohistochemistry. Product of scores for quantity and quality of staining were calculated (immunoreactive score, 0-9). Somatic mutations of Kirsten rat sarcoma viral oncogene homolog [KRAS], epithelial growth factor receptor [EGFR], v-Raf murine sarcoma viral oncogene homolog B [BRAF] and phosphatidylinositol 3-kinase [PIK3CA]) were detected by Sanger (2012-03/2015) and amplicon NGS (04/2015-02/2016). Patients enrolled during the first year (2012) were used as discovery cohort. Patients enrolled from 2013 to 02/2016 were used as validation cohort. Clinical data were retrieved from the electronic medical records and were analyzed retrospectively.

RESULTS

Using a discovery cohort, we identified an immunoreactive score of p-ERK ≥3 to be prognostically relevant. The validation cohort confirmed that higher levels of p-ERK correlated with worse overall survival (OS) and higher proportion of RAS mutations. Multivariate analysis including established risk factors such EGFR, ALK or ROS mutations and metastatic disease showed a trend of a detrimental effect of high p-ERK on OS (HR 1.23, CI 0.94-1.59, p = 0.131 for p-ERK immunoreactive score ≥3) and time to treatment failure after first-line therapy in the validation cohort. Phosphorylated AKT did not correlate with clinical outcome.

CONCLUSION

While serving as a prognosticator in univariate analysis, highly phosphorylated ERK does not convey a significant prognostic effect for OS in the presence of other prognostic factors. Phosphorylated ERK indicates a higher activity of RAS in advanced NSCLC.

A Phase Ib/II Study of the BRAF Inhibitor Encorafenib Plus the MEK Inhibitor Binimetinib in Patients with BRAFV600E/K -mutant Solid Tumors

PURPOSE

This open-label, dose-finding phase Ib/II study reports the safety and activity of the first combination use with BRAF inhibitor (BRAFi) encorafenib plus MEK inhibitor (MEKi) binimetinib in patients with BRAF V600E-mutant solid tumors.

PATIENTS AND METHODS

In phase I, the recommended phase 2 doses (RP2D) were established (primary objective). In phase II, the clinical activity of the combination at the RP2D was assessed (primary objective) in patients with BRAF-mutant metastatic colorectal cancer (mCRC), BRAFi-treated BRAF-mutant melanoma, and BRAFi-naïve BRAF-mutant melanoma.

RESULTS

A total of 126 patients with BRAF-mutant solid tumors were enrolled (phase I: 47 patients; phase II: 79 patients). The RP2D was encorafenib 450 mg once daily plus binimetinib 45 mg twice daily and pharmacokinetic data suggest that drug exposures of each agent were similar in combination compared with single-agent studies. In the phase II cohorts, confirmed responses were seen in two of 11 (18%) evaluable patients with mCRC, 11 of 26 (42%) evaluable patients with BRAFi-pretreated melanoma, and 28 of 42 (67%) BRAFi-naïve patients with melanoma. The most common grade 3/4 adverse event in phase II was increased alanine aminotransferase.

CONCLUSIONS

The combination of encorafenib (450 mg) plus binimetinib (45 mg) showed acceptable tolerability and encouraging activity in patients with BRAF V600-mutant tumors, which led to the dose selection for the melanoma COLUMBUS study. The safety profile of the combination was consistent with other approved BRAFi plus MEKi regimens, with several differences, including lower rates of dose-limiting pyrexia, arthralgia, and photosensitivity.

The discovery and development of binimetinib for the treatment of melanoma

INTRODUCTION

Binimetinib is an uncompetitive, small-molecule inhibitor of selective mitogen-activated protein kinase (MEK1/2) and was recently approved in 2018 in combination with encorafenib for the treatment of metastatic melanomas. Preclinical and clinical trial data on the drug demonstrate its potent efficacy in cancers, especially melanomas with BRAF and NRAS mutations.

AREAS COVERED

The authors review the preclinical as well as clinical Phase 1, 2 and 3 trial data leading to its FDA approval in 2018 for metastatic melanoma. Phase 3 data in combination with encorafenib demonstrated double the PFS (14.9 months) compared to vemurafenib alone (7.3 months) in patients with BRAF-mutated metastatic melanoma.

EXPERT OPINION

No longer-term data is available yet to demonstrate any durable complete responses to therapy with binimetinib or improvements in overall survival compared to other FDA-approved therapies including immunotherapy or vemurafenib. Treatment approaches to patients with BRAF-mutated metastatic melanoma should be individualized and binimetinib in combination with encorafenib is a reasonable oral strategy with a reasonably tolerated toxicity profile. The cost of treatment and durability of response should be incorporated into the discussion as part of the overall medical decision-making.

Randomised phase II trial (SWOG S1310) of single agent MEK inhibitor trametinib Versus 5-fluorouracil or capecitabine in refractory advanced biliary cancer

BACKGROUND

The rationale for the evaluation of trametinib in advanced biliary cancer (BC) is based on the presence of mitogen-activated protein kinase alterations and on earlier promising results with MEK inhibitors in BC.

METHODS

Patients with histologically proven BC who progressed on gemcitabine/platinum were randomised to trametinib daily (arm 1) versus fluoropyrimidine therapy (infusional 5-fluorouracil or oral capecitabine, arm 2). The primary end-point was overall survival (OS). Secondary end-points included progression free survival (PFS) and response rate. A planned interim futility analysis of objective response was performed on the first 14 patients registered to the trametinib arm.

RESULTS

The study was stopped early based on the lack of measurable response in the trametinib arm. A total of 44 eligible patients were randomised (24 patients in arm 1 and 20 patients in arm 2). Median age was 62 years and the primary sites of tumour were cholangiocarcinoma (68%) and gallbladder (32%). The overall response rate was 8% (95% CI 0%-19%) in arm 1 versus 10% (95% CI 0%-23%) in arm 2 (p > .99) Median OS was 4.3 months for arm 1 and 6.6 months for arm 2. The median PFS was 1.4 months for arm 1 and 3.3 months for arm 2.

CONCLUSIONS

This is the first prospective randomised study of a targeted agent versus chemotherapy for the second-line treatment of BC. In this unselected population, the interim analysis result of unlikely benefit with trametinib resulted in early closure.

Current Insights into Combination Therapies with MAPK Inhibitors and Immune Checkpoint Blockade

The recent development of high-throughput genomics has revolutionized personalized medicine by identifying key pathways and molecular targets controlling tumor progression and survival. Mitogen-activated protein kinase (MAPK) pathways are examples of such targets, and inhibitors against these pathways have shown promising clinical responses in patients with melanoma, non-small-cell lung cancer, colorectal cancer, pancreatic cancer, and thyroid cancer. Although MAPK pathway-targeted therapies have resulted in significant clinical responses in a large proportion of cancer patients, the rate of tumor recurrence is high due to the development of resistance. Conversely, immunotherapies have shown limited clinical responses, but have led to durable tumor regression in patients, and complete responses. Recent evidence indicates that MAPK-targeted therapies may synergize with immune cells, thus providing rationale for the development of combination therapies. Here, we review the current status of ongoing clinical trials investigating MAPK pathway inhibitors, such as BRAF and MAPK/ERK kinase (MEK) inhibitors, in combination with checkpoint inhibitors targeting programmed death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T cell associated antigen-4 (CTLA-4). A better understanding of an individual drug's mechanism of action, patterns of acquired resistance, and the influence on immune cells will be critical for the development of novel combination therapies.

Vorinostat in patients with resistant BRAFV600E mutated advanced melanoma: a proof of concept study

The clinical benefit of treatment with BRAF- and MEK-inhibitors in melanoma is limited due to resistance associated with emerging secondary mutations. Preclinical and clinical studies have shown that short-term treatment with the HDAC inhibitor vorinostat can eliminate cells harboring these secondary mutations causing resistance. This proof of concept study is to determine the efficacy of sequential treatment with vorinostat and BRAFi/MEKi in resistant BRAF^V600E mutant melanoma. The primary aim is demonstrating anti-tumor response of progressive lesions according to RECIST 1.1. Secondary end points are to determine that emerging resistant clones with a secondary mutation in the MAPK pathway can be detected in circulating tumor DNA and purged by short-term vorinostat treatment. Exploratory end points include pharmacokinetic, pharmacodynamic and pharmacogenetic analyses (NCT02836548).

The choice for the optimal therapy in advanced biliary tract cancers: Chemotherapy, targeted therapies or immunotherapy

Biliary tract cancers (BTCs) represent a heterogeneous group that includes intrahepatic cholangiocarcinomas (CCAs), perihilar-CCAs or Klatskin tumors, extrahepatic-CCAs, and gallbladder adenocarcinoma. These entities have distinct demographics, risk factors, clinical presentation, and molecular characteristics. In advanced BTCs, the recommendations are mainly supporting a doublet chemotherapy regimen using cisplatin/gemcitabine (CisGem) with a 5-year overall survival rate close to 5% and median overall survival (mOS) of less than a year. The lack of overall efficacy stresses the need for personalized therapies. Recently, whole-genome and transcriptome sequencing highlighted the diversity of BTCs' subtypes. Distinct genetic alterations were retrieved according to the localization, with a high rate of potentially actionable alterations. Targeted therapies and immunotherapy have since then been tested for BTCs, trying to propose a more personalized treatment. This review describes the different therapeutic options, validated and in development, for patients with advanced BTCs.

MEK1/2 as a Therapeutic Target in Sickle Cell Disease

Identification of novel therapeutic targets has improved diagnostics and treatment of many diseases. Many innovative treatment strategies have been developed based on the newly identified biomarkers and key molecules. Most of the research focused on ways to manipulate signaling pathways by activating or suppressing them, validate new therapeutic targets for treatment, and epigenetic treatment of diseases. With the identification of aberrations in multiple growth pathways, the focus then shifted to the small molecules involved in these pathways for targeted therapy. In this communication/short review, we highlight the importance of identification of abnormal activation of the mitogen-activated protein kinase (MAPK), ERK1/2, and its upstream mediator MEK1/2, in erythrocytes in patients with sickle cell disease (SCD) critical for the adhesive interactions of these cells with the endothelium, and leukocytes promoting circulatory obstruction leading to tissue ischemia and infraction. We also discuss how targeting this signaling cascade with MEK1/2 inhibitors can reverse acute vasoocclusive crises in SCD.

A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer

The mitogen-activated protein kinase (MAPK) pathway is an important bridge in the switch from extracellular signals to intracellular responses. Alterations of signaling cascades are found in various diseases, including cancer, as a result of genetic and epigenetic changes. Numerous studies focused on both the homeostatic and the pathologic conduct of MAPK signaling; however, there is still much to be deciphered in terms of regulation and action models in both preclinical and clinical research. MAPK has implications in the response to cancer therapy, particularly the activation of the compensatory pathways in response to experimental MAPK inhibition. The present paper discusses new insights into MAPK as a complex cell signaling pathway with roles in the sustenance of cellular normal conduit, response to cancer therapy, and activation of compensatory pathways. Unfortunately, most MAPK inhibitors trigger resistance due to the activation of compensatory feed-back loops in tumor cells and tumor microenvironment components. Therefore, novel combinatorial therapies have to be implemented for cancer management in order to restrict the possibility of alternative pathway activation, as a perspective for developing novel therapies based on integration in translational studies.

Severe Drug-Induced Liver Injury from Combination Encorafenib/Binimetinib

Encorafenib/binimetinib is a new combination BRAF/MEK inhibitor used in the treatment of advanced or metastatic BRAFV600-mutant melanoma. Though generally tolerated well, mild to moderate aminotransferase elevations are common. However, significant liver injury has not been demonstrated in the literature. Here, we report the first case of severe hepatic injury associated with encorafenib/binimetinib in a 58-year-old gentleman requiring admission and extensive workup. He was successfully treated by withdrawing the combination therapy, and liver function returned to normal range.

Enhanced antitumor effect of binimetinib in combination with capecitabine for biliary tract cancer patients with mutations in the RAS/RAF/MEK/ERK pathway: phase Ib study

BACKGROUND

A phase Ib study of binimetinib and capecitabine for gemcitabine-pretreated biliary tract cancer (BTC) patients was conducted.

METHODS

Binimetinib and capecitabine were dosed twice daily on days 1-14, in 3-week cycles. In the dose-escalation (DE) part, three dose levels (DL) were tested (DL1: binimetinib/capecitabine, 15 mg/1000 mg/m2; DL2: 30 mg/1000 mg/m2; DL3: 30 mg/1250 mg/m2).

RESULTS

In the DE part, nine patients were recruited and no dose-limiting toxicity was noted. Therefore, the recommended phase 2 dose was determined as DL3. In the expansion part, 25 patients were enrolled. In total, 34 patients, 25 (73.5%) and 9 patients (26.5%) were second-line and third-line settings, respectively. The 3-month progression-free survival (PFS) rate was 64.0%, and the median PFS and overall survival (OS) were 4.1 and 7.8 months. The objective response rate and disease control rate were 20.6% and 76.5%. In total, 68.4% of stable diseases were durable (> 12 weeks). Furthermore, patients with RAS/RAF/MEK/ERK pathway mutations (38.5%) showed significantly better tumour response (p = 0.028), PFS (5.4 vs. 3.5 months, p = 0.010) and OS (10.8 vs. 5.9 months, p = 0.160) than wild type. Most of the adverse events were grade 1/2 and manageable.

CONCLUSIONS

A combination of binimetinib and capecitabine shows acceptable tolerability and promising antitumor efficacy for gemcitabine-pretreated BTC, especially in patients with RAS/RAF/MEK/ERK pathway mutations.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (Identifier: NCT02773459).

PI3K-AKT-mTOR and NFκB Pathways in Ovarian Cancer: Implications for Targeted Therapeutics

Ovarian cancer is the most lethal gynecologic malignancy in the United States, with an estimated 22,530 new cases and 13,980 deaths in 2019. Recent studies have indicated that the phosphoinositol 3 kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), as well as the nuclear factor-κ light chain enhancer of activated B cells (NFκB) pathways are highly mutated and/or hyper-activated in a majority of ovarian cancer patients, and are associated with advanced grade and stage disease and poor prognosis. In this review, we will investigate PI3K/AKT/mTOR and their interconnection with NFκB pathway in ovarian cancer cells.

Binimetinib, a novel MEK1/2 inhibitor, exerts anti-leukemic effects under inactive status of PI3Kinase/Akt pathway

A MEK1/2 inhibitor, binimetinib is promising as a therapeutic agent for malignant melanoma with N-RAS mutation. We examined in vitro effects of binimetinib on 10 human myeloid/lymphoid leukemia cell lines, and found that three of five cell lines with N-RAS mutation and one of five without N-RAS mutation were responsive to treatment with binimetinib. Binimetinib inhibited cell growth mainly by inducing G₁ arrest and this action mechanism was assisted by gene set enrichment analysis. To identify signaling pathways associated with binimetinib response, we examined the status of MAP kinase/ERK and PI3Kinase/Akt pathways. The basal levels of phosphorylated ERK and Akt varied between the cell lines, and the amounts of phosphorylated ERK and Akt appeared to be reciprocal of each other. Interestingly, most of the binimetinib-resistant cell lines revealed strong Akt phosphorylation compared with binimetinib-sensitive ones. The effect of binimetinib may not be predicted by the presence/absence of N-RAS mutation, but rather by Akt phosphorylation status. Moreover, combination of binimetinib with a PI3K/Akt inhibitor showed additive growth-suppressive effects. These results suggest that binimetinib shows potential anti-leukemic effects and the basal level of phosphorylated Akt might serve as a biomarker predictive of therapeutic effect.

Tolerability of BRAF/MEK inhibitor combinations: adverse event evaluation and management

The inhibition of the mitogen-activated protein kinases signalling pathway through combined use of BRAF and MEK inhibitors (BRAFi+MEKi) represents an established therapeutic option in patients with BRAF-mutated, advanced melanoma. These efficient therapies are well tolerated with mostly moderate and reversible side effects and a discontinuation rate due to adverse events of 11.5%-15.7%. Median duration of therapy ranges between 8.8 and 11.7 months. Based on data from confirmatory trials, safety profiles of three BRAFi+MEKi combinations were reviewed, that is, dabrafenib plus trametinib, vemurafenib plus cobimetinib and encorafenib plus binimetinib. Many adverse events are class effects, such as cutaneous, gastrointestinal, ocular, cardiac and musculoskeletal events; some adverse events are substance associated. Fever (dabrafenib) and photosensitivity (vemurafenib) are the most common and clinically prominent examples. Other adverse events are less frequent and the association to one substance is less strong such as anaemia, facial paresis (encorafenib), neutropenia (dabrafenib), skin rash, QTc prolongation and increased liver function tests (vemurafenib). This narrative review provides recommendations for monitoring, adverse event evaluation and management focusing on the clinically relevant side effects of the three regimens.

Melanoma: the new perspectives from clinical and translational research

The prognosis of metastatic melanoma has not changed throughout the 20th century. However, in the last decade, we have witnessed a continuous improvement in survival, with many long-term survivors. These results are largely because of the simultaneous development of the knowledge in the biology of metastatic malignant melanoma and of the relationship between the disease and the host's immune system that allowed the development of effective new treatments. In this overview, we summarize the therapies available today, their biological rationale, and the research field currently under investigation divided into three main chapters: target therapies, immunotherapies, and their combination.

Phase II Trial of MEK Inhibitor Binimetinib (MEK162) in RAS-mutant Acute Myeloid Leukemia

BACKGROUND

Relapsed and refractory (R/R) acute myeloid leukemia (AML) continues to be a therapeutic challenge with poor outcomes. Dysregulation of the mitogen-activated protein (MAP) kinase/extracellular-signal regulated kinase (ERK) pathway frequently occurs in AML and myelodysplastic syndrome (MDS). Preclinical studies and early-phase trials have shown promise for MAP-ERK kinase (MEK) inhibition in AML. We evaluated the safety and efficacy of the MEK 1/2 inhibitor binimetinib in advanced myeloid malignancies.

PATIENTS AND METHODS

Nineteen patients with R/R AML and MDS, who were not candidates for intensive chemotherapy or with disease resistance or intolerance to standard treatment were enrolled in the present phase II study of binimetinib dosed twice daily continuously in 28-day cycles.

RESULTS

The median age of the cohort was 64 years (range, 31-85 years). These patients had received a median of 3 previous lines of therapy (range, 1-6). The median bone marrow blast percentage was 49% (range, 2%-94%), and 14 patients had RAS mutations. The patients received a median of 2 cycles (range, 1-4 cycles) of binimetinib and received treatment for a median duration of 1.2 months (range, 0.1-3.4 months). Sixteen patients (84%) received the 45-mg twice daily dose. The most common grade 3/4 treatment-emergent adverse events were hypokalemia (6%), hypotension (6%), lung infection (6%), and febrile neutropenia (6%). No treatment-related deaths occurred. One of the 13 evaluable patients (8%) achieved a complete response with incomplete blood count recovery lasting 2.1 months. The other 12 patients (92%) did not have a response. Six patients could not be evaluated.

CONCLUSION

Binimetinib had tolerable safety profile with a minimal response in RAS-mutant AML. Future studies should focus on better patient selection and synergistic combination therapies involving MEK inhibition.

Combined MEK and BCL-2/XL Inhibition Is Effective in High-Grade Serous Ovarian Cancer Patient-Derived Xenograft Models and BIM Levels Are Predictive of Responsiveness

Most patients with late-stage high-grade serous ovarian cancer (HGSOC) initially respond to chemotherapy but inevitably relapse and develop resistance, highlighting the need for novel therapies to improve patient outcomes. The MEK/ERK pathway is activated in a large subset of HGSOC, making it an attractive therapeutic target. Here, we systematically evaluated the extent of MEK/ERK pathway activation and efficacy of pathway inhibition in a large panel of well-annotated HGSOC patient-derived xenograft models. The vast majority of models were nonresponsive to the MEK inhibitor cobimetinib (GDC-0973) despite effective pathway inhibition. Proteomic analyses of adaptive responses to GDC-0973 revealed that GDC-0973 upregulated the proapoptotic protein BIM, thus priming the cells for apoptosis regulated by BCL2-family proteins. Indeed, combination of both MEK inhibitor and dual BCL-2/XL inhibitor (ABT-263) significantly reduced cell number, increased cell death, and displayed synergy in vitro in most models. In vivo, GDC-0973 and ABT-263 combination was well tolerated and resulted in greater tumor growth inhibition than single agents. Detailed proteomic and correlation analyses identified two subsets of responsive models-those with high BIM at baseline that was increased with MEK inhibition and those with low basal BIM and high pERK levels. Models with low BIM and low pERK were nonresponsive. Our findings demonstrate that combined MEK and BCL-2/XL inhibition has therapeutic activity in HGSOC models and provide a mechanistic rationale for the clinical evaluation of this drug combination as well as the assessment of the extent to which BIM and/or pERK levels predict drug combination effectiveness in chemoresistant HGSOC.

Safety Profiles and Pharmacovigilance Considerations for Recently Patented Anticancer Drugs: Cutaneous Melanoma

BACKGROUND

Malignant melanoma is a skin cancer responsible for 90% of cutaneous cancer- related deaths. In recent years, breakthroughs in treatment strategy have revolutionized the prognosis in both early and advanced melanoma patients. In particular, treatment with monoclonal antibodies targeting co-inhibitory checkpoints or specific molecular pathways leads to a new era of promising options, by prolonging the survival time of these patients. Moreover, unlike the chemotherapy that was used until some time ago, these new drugs have a good and more manageable toxicity profile. However, because of the recent introduction in clinical practice of the new agents, there is a learning curve among physicians regarding early recognition and management of the associated side effects.

OBJECTIVES

The analysis of the toxicity profiles of the different agents currently studied for the treatment of early and advanced melanoma, and the description of several relevant recent patents in this field, are the aims of this review.

METHODS

This is a systematically conducted review based on current clinical guidelines and on international Pharmacovigilance databases (AERS-Eudravigilance - WHO Vigibase).

RESULTS

Our systematic analysis outlines a comprehensive overview of the pharmacology, clinical application and the safety of recent anticancer drugs to treat melanoma, which can be an essential instrument for health professionals and researchers.

CONCLUSION

The new oncological therapies against melanoma are based on increasingly specific biological and immunological targets. For this reason, the potential toxicities that are expected from patients would be less relevant than the systemic "classical" chemotherapy. However, the new therapies are not free from the risk of causing adverse reactions, some of which must be managed promptly and appropriately; moreover, the multiplicity of the metabolic pathways exposes the new target therapies to relevant potential interactions. This review can help to understand how important it is not to underestimate potential adverse drug reactions related to new targeted therapies.

Binimetinib plus Gemcitabine and Cisplatin Phase I/II Trial in Patients with Advanced Biliary Cancers

PURPOSE

Mutations in the RAS/RAF/MEK/ERK signaling pathway are commonly found in biliary tract cancer (BTC). Binimetinib, a selective inhibitor of MEK1/2, has single-agent activity. Preclinical data support binimetinib combination with chemotherapy, when given in an interrupted dosing schedule.Patients and Methods: A phase I/II trial evaluated binimetinib in combination with gemcitabine and cisplatin in patients with untreated advanced BTC. The primary endpoints were to determine the MTD (phase I), and PFS 6 and RR (phase II). Tumor tissue for targeted gene sequencing and blood samples for peripheral blood pERK expression were evaluated. Patients received oral binimetinib twice daily with gemcitabine and cisplatin on day 8 and 15 of a 21-day cycle. Binimetinib was held for 2 days prior to and on day of each chemotherapy treatment.

RESULTS

Twelve patients enrolled in the phase I showed the MTD of binimetinib at 45 mg orally twice daily with gemcitabine 800 and cisplatin 20 mg/m². Twenty-nine patients were treated in the phase II. Six patients treated at MTD in phase I were evaluable as part of phase II. PFS 6 months was 54% and RR was 36%. Median overall survival was 13.3 months (95% CI, 9.8-16.5). MSK-IMPACT 410-gene panel showed aberrations in the RAS-RAF-MEK-ERK pathway and mutations in PIK3CA, AKT2, PIK3CG, BRAF, and MAP3K1 in responding patients.

CONCLUSIONS

Binimetinib with gemcitabine and cisplatin did not show an improvement in PFS 6 and RR. Molecular profiling may help select patients who may benefit from this triplet therapy, which is not planned at this time.

Encorafenib/binimetinib for the treatment of BRAF-mutant advanced, unresectable, or metastatic melanoma: design, development, and potential place in therapy

Major advances in the understanding of the pathophysiology of melanoma have led to a new era of melanoma treatment with targeted therapy and immunotherapies. Since 2011, four new classes of medications with unique mechanisms of action have been approved, which allow melanoma to be treated at many different stages in its development. These include the checkpoint inhibitors anti-PD1/PDL-1 and anti-CTLA4, as well as BRAF inhibitors and MEK inhibitors. The latter two were developed to directly inhibit key components in the MAP kinase pathway with significant breakthrough in the treatment of metastatic and unresectable melanoma. In this review, we discuss the development of targeted therapy of melanoma up to the latest agents encorafenib and binimetinib, including mechanisms of action, adverse effects, and the latest data on treatment response. Current ongoing trials will continue to elucidate these medications and their ultimate impact on melanoma therapy.

Novel targeted treatment options for advanced cholangiocarcinoma

INTRODUCTION

Surgical resection remains the mainstay of potentially curative treatment in the early stages of cholangiocarcinoma, whereas for the advanced stage, systemic chemotherapeutics and experimental targeted therapies are the primary treatment options. The molecular heterogeneity of the tumor is based on location, liver dysfunction, and relative rarity of the disease and confers challenges for clinical trial enrollment. The advancements in the understanding of molecular pathogenesis of cholangiocarcinoma have led to the development of targeted therapies that are currently being evaluated in the clinical trials.

AREAS COVERED

This review summarizes the current understanding and future directions of targeted therapeutic options in the management of advanced cholangiocarcinoma.

EXPERT OPINION

Advanced cholangiocarcinoma has a dismal prognosis; improved understanding of the molecular pathogenesis and advancements in development of targeted therapy offers hope that we may improve outcomes in this rare, but highly lethal cancer. Among the newly discovered molecular alterations, targeting FGFR2 fusions, IDH1/2 mutations and HER2 receptors hold great promise for improving the future management of cholangiocarcinoma. Immunotherapy in combination with targeted agents and chemotherapy may improve outcomes. In addition, drugs targeting the MEK, EGFR, KRAS, BRAF, and ROS1 pathways and neo-angiogenesis may also provide new horizons in the management of cholangiocarcinoma.

MEK inhibitors for the treatment of NRAS mutant melanoma

Melanoma is increasing rapidly in incidence and prevalence, especially in younger females and older males. Treatment options have expanded beyond high-dose interleukin 2 and adoptive T-cell therapy to include inhibitors of immune checkpoints programmed death 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and small molecular inhibitors of pathways activated in melanoma, in particular the mitogen-activated protein kinase (MAPK) pathway. PD-1/CTLA-4 inhibitors and inhibitors of MAPK such as BRAF/MEK inhibitors have significantly improved survival in both the metastatic and, more recently, adjuvant settings. In this review, we discuss the preclinical data, clinical development, and potential use of novel MEK inhibitor binemetinib, particularly in the setting of NRAS mutant melanoma.

Binimetinib (MEK162) in recurrent low-grade serous ovarian cancer resistant to chemotherapy and hormonal treatment

Background

Management of advanced/recurrent low-grade serous ovarian carcinoma (LGOSC) is often challenging. Effective treatment options remain limited for hormone and chemotherapy-resistant LGSOC.

CASE: A 65-year-old woman with recurrent widespread LGSOC harboring the KRAS-G12 V hotspot mutation experienced a dramatic clinical response to Binimetinib (MEK162), a mitogen-activated protein kinase (MEK) inhibitor, after failing multiple chemotherapy and hormonal treatments. An 81% reduction of target lesions by RECIST 1.1 over 31 months of response duration was confirmed with serial CT scans. Episodes of drug-related toxicity (pneumonitis) easily resolved without sequelae with the use of oral steroids.

Conclusion

Binimetinib may present a new treatment option for hormone- and chemotherapy-resistant LGSOC harboring KRAS mutations.

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Low-grade serous ovarian carcinoma (LGSOC) is chemotherapy resistant.

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RAS-RAF-MEK-ERK pathway activation by BRAF and KRAS mutations are common in LGSOC.

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Binimetinib (MEK162) is a non-ATP-competitive MEK 1/2 inhibitor.

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MEK162 may represent an effective treatment in LGSOC with BRAF and KRAS mutations.

Phase 1b investigation of the MEK inhibitor binimetinib in patients with advanced or metastatic biliary tract cancer

Background The MAPK pathway plays a central role in regulation of several cellular processes, and its dysregulation is a hallmark of biliary tract cancer (BTC). Binimetinib (MEK162), a potent, selective oral MEK1/2 inhibitor, was assessed in patients with advanced BTC. Patients and Methods An expansion cohort study in patients who received ≤1 line of therapy for advanced BTC was conducted after determination of the maximum tolerated dose in this Phase 1 trial. Patients received binimetinib 60 mg twice daily. The primary objectives were to characterize the safety profile and pharmacokinetics of binimetinib in advanced BTC. Secondary objectives included assessment of clinical efficacy, changes in weight and lean body mass, and pharmacodynamic effects. Tumor samples were assessed for mutations in relevant genes. Results Twenty-eight patients received binimetinib. Common adverse events (AEs) were mild, with rash (82%) and nausea (54%) being most common. Two patients experienced grade 4 AEs, one generalized edema and the other pulmonary embolism. The pharmacokinetics in this patient population were consistent with those previously reported (Bendell JC et al., Br J Cancer 2017;116:575-583). Twelve patients (43%) experienced stable disease and two had objective responses (1 complete response, 1 partial response) per Response Evaluation Criteria in Solid Tumors and stable metabolic disease by positron emission tomography/computed tomography. Most patients (18/25; 72%) did not have KRAS, BRAF, NRAS, PI3KCA, or PTEN mutations, nor was there correlation between mutation status and response. The average non-fluid weight gain was 1.3% for lean muscle and 4.7% for adipose tissue. Conclusion Binimetinib was well tolerated and showed promising evidence of activity in patients with BTC. Correlative studies suggested the potential for binimetinib to promote muscle gain in patients with BTC.

Dual blockade of PI3K and MEK in combination with radiation in head and neck cancer

Background and purpose

In this study we have combined fractionated radiation treatment (RT) with two molecular targeted agents active against key deregulated signaling pathways in head and neck cancer.

Materials and methods

We used two molecularly characterized, low passage HNSCC cell lines of differing biological characteristics to study the effects of binimetinib and buparlisib in combination with radiation in vitro and in vivo.

Results

Buparlisib was active against both cell lines in vitro whereas binimetinib was more toxic to UT-SCC-14. Neither agent modified radiation sensitivity in vitro. Buparlisib significantly inhibited growth of UT-SSC-15 alone or in combination with RT but was ineffective in UT-SCC-14. Binimetinib did cause a significant delay with RT in UT-SCC-14 and it significantly reduced growth of the UT-SCC-15 tumors both alone and with RT. The tri-modality treatment was not as effective as RT with a single effective agent.

Conclusions

No significant benefit was gained by the combined use of the two agents with RT even though each was efficacious when used alone.

Characterization of a conjunctival melanoma cell line CM-AS16, newly-established from a metastatic Han Chinese patient

Conjunctival melanoma (CM) is associated with metastases formation, can be fatal, and occurs in all different races. While cell lines are essential for experimental research, all available CM cell lines are derived from Caucasian patients. Furthermore, they are not derived from metastases. We aimed to establish a new CM cell line from a parotid metastasis in a Han Chinese patient and to depict its characteristics. The novel cell line, CM-AS16, was obtained from a surgical parotid sample and determined as a unique one with short tandem repeat (STR) analysis. It has been successively sub-cultured in vitro for more than 100 passages and exhibits rapid proliferation and migration. Chromosome analysis shows abundant chromosome aberrations, while whole exome sequencing (WES) reveals a typical NRAS mutation (Q61R). In vivo tumor growth was successfully established in a NOD/SCID mice model, and the immunophenotypes, such as HMB45, Melan A, S100, SOX10 and Ki67, manifested similar between the original tumor and the xenograft by immunohistochemistry. A MEK inhibitor binimetinib prominently suppressed in vitro cell growth by inhibiting ERK1/2 phosphorylation. In addition, monoclonal cells were used to demonstrate the drug sensitivity of different cells. In conclusion, the first cell line, CM-AS16, that is derived from a CM in a Han Chinese patient has highly malignant characteristics and a typical NRAS mutation. It may be used as a tool for further exploration of the molecular mechanisms of CM.

BRAF and MEK Inhibitors: Use and Resistance in BRAF-Mutated Cancers

The mitogen activated protein kinase/extracellular signal-related kinase (MAPK/ERK) signaling pathway serves an integral role in growth, proliferation, differentiation, migration, and survival of all mammalian cells. Aberrant signaling of this pathway is often observed in several types of hematologic and solid malignancies. The most frequent insult to this signaling cascade, leading to its constitutive activation, is to the serine/threonine kinase rapidly accelerating fibrosarcoma (RAF). Considering this, the development and approval of various small-molecule inhibitors targeting the MAPK/ERK pathway has become a mainstay of treatment as either mono- or combination therapy in these cancers. Although effective initially, a major clinical barrier with these inhibitors is the relapse of patients due to drug resistance. Knowledge of the mechanisms of resistance to these drugs is still premature, highlighting the need for a more in-depth understanding of how patients become insensitive to these pharmacologic interventions. Herein, we will succinctly summarize the milestones in the approval of select MAPK/ERK pathway inhibitors, their use in patients, and major modes of resistance.

Small molecule purine and pseudopurine derivatives: synthesis, cytostatic evaluations and investigation of growth inhibitory effect in non-small cell lung cancer A549

Novel halogenated purines and pseudopurines with diverse aryl-substituted 1,2,3-triazoles were prepared. While p-(trifluoromethyl)-substituted 1,2,3-triazole in N-9 alkylated purine and 3-deazapurine was critical for strong albeit unselective activity on pancreatic adenocarcinoma cells CFPAC-1,1-(p-fluorophenyl)-1,2,3-triazole derivative of 7-deazapurine showed selective cytostatic effect on metastatic colon cancer cells SW620. Importantly, 1-(p-chlorophenyl)-1,2,3-triazole-tagged benzimidazole displayed the most pronounced and highly selective inhibitory effect in nM range on non-small cell lung cancer A549. This compound revealed to target molecular processes at the extracellular side and inside the plasma membrane regulated by GPLD1 and growth factor receptors PDGFR and IGF-1R leading to the inhibition of cell proliferation and induction of apoptosis mediated by p38 MAP kinase and NF-κB, respectively. Further optimisation of this compound as to reduce its toxicity in normal cells may lead to the development of novel agent effective against lung cancer.

Challenges in Ras therapeutics in pancreatic cancer

Pancreatic cancer is considered among the most aggressive and the least curable of all human malignancies. It is usually characterized by multiple aberrations in tumor suppressor genes and oncogenes, most notably activating mutations in KRAS. This review examines the various attempts that have been made to inhibit Kras and its downstream signaling pathways in pancreatic cancer with an emphasis on challenges related to clinical trials. Attempts include preventing the localization of Ras protein to the plasma membrane, inhibiting downstream oncogenic signaling by targeting Kras effectors such as MEK1/2, Erk1/2 or Akt singly or in combination, and directly inhibiting Kras protein. Most clinical trials have focused on inhibiting downstream effector pathways and clinical benefit has been limited due to compensatory mechanisms and toxicity associated with small therapeutic windows. Additionally, genetic screens have been conducted to identify gene or genes that could provide therapeutic vulnerabilities in mutant KRAS cells and provide a way to target mutant Kras protein only. We also discuss how potentially transforming clinical trials have failed in the past and what new strategies are on-going in clinical trials for pancreas cancer. For long-term success in targeting Kras, future efforts should focus on combinatorial strategies to more effectively block Kras pathways at multiple points, and improve translational application of pre-clinical data to the clinic.

Current Development Status of MEK Inhibitors

The current development status of mitogen-activated protein kinase kinase (MEK) inhibitors, including the preclinical data and clinical study progress, has been summarized in this review. Different MEK inhibitors, possessing specific physicochemical properties and bioactivity characteristics, may provide different options for patients seeking treatment for cancer. Moreover, the combination of the MEK inhibitors with other therapies-such as chemotherapy, targeted therapy, and immunotherapy-may be a promising approach for clinical use.

Binimetinib for the treatment of NRAS-mutant melanoma

INTRODUCTION

Activating NRAS mutations occur in approximately 15-20% of melanomas and are the second most common oncogenic driver mutation in this disease, after BRAF mutations. There is an unmet medical need for new targeted therapy opportunities in metastatic patients whose tumors harbor an NRAS mutation. Binimetinib, a mitogen-activated protein kinase kinase (MEK) inhibitor, has shown clinical activity in this group of patients. Areas covered: The purpose of this paper was to review the safety, activity and efficacy of the MEK inhibitor binimetinib for the treatment of NRAS-mutant melanoma, as well as to discuss future therapeutic perspectives such as multiple pathways, targeted therapy, and combinations with immunotherapy. Expert commentary: Only a modest progression-free survival (PFS) benefit was observed in NRAS-mutated patients who received binimetinib compared with dacarbazine in a randomized phase 3 clinical trial, with no improvement in overall survival. Nevertheless, binimetinib represents another promising treatment option for advanced melanoma and the first molecularly targeted therapy for the NRAS-mutant population. Binimetinib may also have a role in treating NRAS-mutated melanoma patients after failure of immunotherapy.

NRAS-mutant melanoma: current challenges and future prospect

Melanoma is one of the most common cutaneous cancers worldwide. Activating mutations in RAS oncogenes are found in a third of all human cancers and NRAS mutations are found in 15%–20% of melanomas. The NRAS-mutant subset of melanoma is more aggressive and associated with poorer outcomes, compared to non-NRAS-mutant melanoma. Although immune checkpoint inhibitors and targeted therapies for BRAF-mutant melanoma are transforming the treatment of metastatic melanoma, the ideal treatment for NRAS-mutant melanoma remains unknown. Despite promising preclinical data, current therapies for NRAS-mutant melanoma remain limited, showing a modest increase in progression-free survival but without any benefit in overall survival. Combining MEK inhibitors with agents inhibiting cell cycling and the PI3K–AKT pathway appears to provide additional benefit; in particular, a strategy of MEK inhibition and CDK4/6 inhibition is likely to be a viable treatment option in the future. Patients whose tumors had NRAS mutations had better response to immunotherapy and better outcomes than patients whose tumors had other genetic subtypes, suggesting that immune therapies – especially immune checkpoint inhibitors – may be particularly effective as treatment options for NRAS-mutant melanoma. Improved understanding of NRAS-mutant melanoma will be essential to develop new treatment strategies for this subset of patients with melanoma.

A review of binimetinib for the treatment of mutant cutaneous melanoma

Although significant progress has been made in the treatment of unresectable or metastatic melanoma, at least half of all advanced melanoma patients eventually progress and pass away due to their disease. In particular, patients with NRAS-mutated melanoma still face limited therapeutic options, with immunotherapy being the current treatment type of choice. Binimetinib is a selective inhibitor of MEK, a central kinase in the tumor-promoting MAPK pathway. The results of a recent Phase III trial rendered binimetinib the first targeted therapy agent to significantly improve progression-free survival in NRAS-mutated melanoma. This review will summarize the development and clinical data of binimetinib in melanoma in general and also explore the potential future role of this substance as single agent or combination therapy.