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Background and Aims: Dual blockade of BRAF and MEK kinases is a standard of care for metastatic V600E/K BRAF mutant melanoma. This study reports the first systematic description of colitis due to BRAF and MEK inhibitors., Methods: We studied consecutive patients with melanoma, treated with BRAF and MEK inhibitors, who had colitis requiring hospitalisation. Electronic files were studied; endoscopic biopsies and colectomy specimens were read centrally., Results: Between January 2021 and March 2022, nine women and one man, aged 50-90 years, were studied. Nine patients received encorafenib and binimetinib; one patient received dabrafenib and trametinib. The main symptoms were diarrhoea, haematochezia, abdominal pain and intestinal obstruction. Blood tests showed anaemia, increased CRP and low serum albumin levels in most patients. All patients had ulcerations of the right colon with (2/10) or without (8/10) stenosis of the ileocecal valve, and 4/10 patients also had ulcerations distal to the right colon. Histopathological findings were suggestive of ischaemia and mild inflammation. Nine of the 10 patients discontinued BRAF/MEK inhibitors. Drugs were reintroduced in four patients, three of whom had a severe relapse of diarrhoea. Two patients required surgery and underwent intestinal resection. One patient died of enterocolitis., Conclusion: BRAF/MEK inhibitors can induce severe colitis characterised by ulcerations of the right colon., (© 2022 John Wiley & Sons Ltd.)

Purpose: Androgen deprivation regenerates the thymus in adults, expanding of T-cell receptor V β repertoire in blood and lymphoid organs and tumor-infiltrating lymphocytes in human prostate tumors. In melanoma murine models, androgen receptor promotes metastases and androgen blockade potentiates antitumor vaccine efficacy. This phase I study evaluated the safety, efficacy, and pharmocodynamics of androgen deprivation with the gonadotropin releasing hormone (GnRH) agonist triptorelin combined with nivolumab in male patients with melanoma resistant to anti-PD-1., Patients and Methods: Adult male patients with advanced melanoma who progressed under anti-PD-1 containing regimens received triptorelin 3.75 mg every 4 weeks, nivolumab 3 mg/kg every 2 weeks, and bicalutamide 50 mg once daily during the first 28 days. Tumor response was first assessed after 3 months; adverse events (AE) were monitored throughout the study. T-cell receptor excision circles (TREC), a biomarker of thymus activity, were explored throughout the study., Results: Of 14 patients, 4 were locally advanced and 10 had distant metastases. There were no grade 4 or 5 AEs. Five grade three AEs were reported in 4 patients. According to RECIST v1.1, best overall response was partial response (PR) in one patient with a pancreas metastasis, stable disease (SD) in 5 patients, and progressive disease in 8 patients. According to iRECIST, a second PR occurred after an initial pseudoprogression, TRECs increased in 2 patients, one with PR who also had an increase in TILs, and the second with SD., Conclusions: This combination was well tolerated. Disease control was obtained in 42.8% (RECIST) and 50% (iRECIST). The evidence for thymus rejuvenation was limited., (©2022 American Association for Cancer Research.)

Purpose: While there is still a significant need to identify potential biomarkers that can predict which patients are most likely to respond to immunotherapy treatments, radiomic approaches have shown promising results. The objectives of this study were to evaluate whether a previously validated radiomics signature of CD8 T-cells could predict progressions at a lesion level and whether the spatial heterogeneity of this radiomics score could be used at a patient level to assess the clinical response and survival of melanoma patients., Methods: Clinical data from patients with advanced melanoma treated in our center with immunotherapy were retrieved. Radiomic features were extracted and the CD8 radiomics signature was applied. A progressive lesion was defined by an increase in lesion size of 20% or more. Dispersion metrics of the radiomics signature were estimated to evaluate the impact of interlesion heterogeneity on patient's response. Fine-tuned cut-offs for predicting overall survival were evaluated after splitting data into training and test sets., Results: A total of 136 patients were included in this study, with 1120 segmented lesions at baseline, and 1052 lesions at first evaluation. A low CD8 radiomics score at baseline was associated with a significantly higher risk of lesion progression (AUC=0.55, p=0.0091), especially for lesions larger than >1 mL (AUC=0.59 overall, p=0.0035, with AUC=0.75, p=0.002 for subcutaneous lesions, AUC=0.68, p=0.01, for liver lesions and AUC=0.62, p=0.03 for nodes). The least infiltrated lesion according to the radiomics score of CD8 T-cells was positively associated with overall survival (training set HR=0.31, p=0.00062, test set HR=0.28, p=0.016), which remained significant in a multivariate analysis including clinical and biological variables., Conclusions: These results confirm the predictive value at a lesion level of the biologically inspired CD8 radiomics score in melanoma patients treated with anti-PD1-based immunotherapy and may be interesting to assess the disease spatial heterogeneity to evaluate the patient prognosis with potential clinical implication such as tumor selection for focal ablative therapies., Competing Interests: Competing interests: ED has declared consulting fees and support from Roche, BMS, Boehringer, Astrazeneca, Lilly Amgen and Merck-Serono. CaR declares consulting fees from Roche, BMS, MSD, AstraZeneca, Pierre Fabre, Sanofi, Novartis., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: Less than 50% of patients with melanoma respond to anti-programmed cell death protein 1 (anti-PD-1), and this treatment can induce severe toxicity. Predictive markers are thus needed to improve the benefit/risk ratio of immune checkpoint inhibitors (ICI). Baseline tumor parameters such as programmed death ligand 1 (PD-L1) expression, CD8 + T-cell infiltration, mutational burden, and various transcriptomic signatures are associated with response to ICI, but their predictive values are not sufficient. Interaction between PD-1 and its main ligand, PD-L1, appears as a valuable target of anti-PD-1 therapy. Thus, instead of looking at PD-L1 expression only, we evaluated the predictive value of the proximity between PD-1 and its neighboring PD-L1 molecules in terms of response to anti-PD-1 therapy., Experimental Design: PD-1/PD-L1 proximity was assessed by proximity ligation assay (PLA) on 137 samples from two cohorts (exploratory n = 66 and validation n = 71) of samples from patients with melanoma treated with anti-PD-1±anti-CTLA-4. Additional predictive biomarkers, such as PD-L1 expression (MELscore), CD8 + cells density, and NanoString RNA signature, were also evaluated., Results: A PD-1/PD-L1 PLA model was developed to predict tumor response in an exploratory cohort and further evaluated in an independent validation cohort. This score showed higher predictive ability (AUC = 0.85 and 0.79 in the two cohorts, respectively) for PD-1/PD-L1 PLA as compared with other parameters (AUC = 0.71-0.77). Progression-free and overall survival were significantly longer in patients with high PLA values ( P = 0.00019 and P < 0.0001, respectively)., Conclusions: The proximity between PD-1 and PD-L1, easily assessed by this PLA on one formalin-fixed paraffin-embedded section, appears as a new biomarker of anti-PD-1 efficacy., (©2021 American Association for Cancer Research.)

Emerging evidence indicates that non-mutational drug tolerance mechanisms underlie the survival of residual cancer "persister" cells. Here, we find that BRAF(V600E) mutant melanoma persister cells tolerant to BRAF/MEK inhibitors switch their metabolism from glycolysis to oxidative respiration supported by peroxisomal fatty acid β-oxidation (FAO) that is transcriptionally regulated by peroxisome proliferator-activated receptor alpha (PPARα). Knockdown of the key peroxisomal FAO enzyme, acyl-CoA oxidase 1 (ACOX1), as well as treatment with the peroxisomal FAO inhibitor thioridazine, specifically suppresses the oxidative respiration of persister cells and significantly decreases their emergence. Consistently, a combination treatment of BRAF/MEK inhibitors with thioridazine in human-melanoma-bearing mice results in a durable anti-tumor response. In BRAF(V600E) melanoma samples from patients treated with BRAF/MEK inhibitors, higher baseline expression of FAO-related genes and PPARα correlates with patients' outcomes. These results pave the way for a metabolic strategy to overcome drug resistance., Competing Interests: Declaration of Interests C.R. is an occasional consultant for Roche, BMS, MSD, Merck, Sanofi, Pierre Fabre, Biothera, CureVac, and Novartis., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: A synergy between radiotherapy and anti-cytotoxic-T-lymphocyte-associated antigen 4 (anti-CTLA-4) monoclonal antibody has been demonstrated preclinically. The Mel-Ipi-Rx phase 1 study aimed to determine the maximum tolerated dose (MTD) and safety profile of radiotherapy combined with ipilimumab in patients with metastatic melanoma., Patients and Methods: A 3+3 dose escalation design was used with 9, 15, 18 and 24 Gy dose of radiotherapy at week 4 combined with 10 mg/kg ipilimumab every 3 weeks for four doses. Patients with evidence of clinical benefit at week 12 were eligible for maintenance with ipilimumab 10 mg/kg every 12 weeks starting at week 24 until severe toxicity or disease progression. The database lock occurred on April 30, 2019. Tumor growth rate of irradiated lesions and non-irradiated lesions were analyzed to assess the systemic immunologic antitumor response. Blood immune monitoring was performed before and during treatment to determine if radiotherapy could modify ipilimumab pharmacodynamics., Results: 19 patients received ipilimumab between August 2011 and July 2015. Nine patients received the four doses of ipilimumab. All patients received the combined radiotherapy. Grade 3 adverse events occurred in nine patients, the most common being colitis and hepatitis. No drug-related death occurred. Dose limiting toxicity occurred in two of six patients in the cohort receiving 15 Gy. The MTD was 9 Gy. Two patients had complete response, three had partial response response and seven had stable disease, giving an objective response rate of 31% and a clinical benefit rate of 75% at week 24. The median duration of follow-up was 5.8 years (Q1=4.5; Q3=6.8). The median overall survival (95% CI) was estimated at 0.9 years (0.5-2). The median progression-free survival (PFS) (95% CI) was 0.4 (0.2-1.4). Radiotherapy combined with ipilimumab was associated with increased CD4+ and CD8+ICOS+ T cells. Increased CD8+ was significantly associated with PFS., Conclusion: When combined with ipilimumab at 10 mg/kg, the MTD of radiotherapy was 9 Gy. This combination of ipilimumab and radiotherapy appears to be associated with antitumor activity. Increased CD8+ was significantly associated with PFS. Thus, immune biomarkers may be useful for early response evaluation., Trial Registration Number: NCT01557114., Competing Interests: Competing interests: CB has acted as a board advisor for BMS, has been a speaker for Merck and has received travel fees from Amgen and Pfizer. NC-G has received research grants from Cytune Pharma, GSK and Sanofi. She has acted as a board advisor for AstraZeneca and has been a speaker for Sanofi and AstraZeneca. CM has acted as consultant of BMS and Merck. ER has acted as a consultant for BMS, Novartis and Roche, and has received travel fees from BMS and Novartis. RS has received travel fees from AstraZeneca. CM has acted as a consultant from Amgen, Astellas, Astra Zeneca, Bayer, BeiGene, BMS, Celgene, Debiopharm, Genentech, Ipsen, Janssen, Lilly, MedImmune, MSD, Novartis, Pfizer, Roche, Sanofi and Orion. He is the principal or subinvestigator of clinical trials for Abbvie, Aduro, Agios, Amgen, Argen-x, Astex, AstraZeneca, Aveopharmaceuticals, Bayer, Beigene, Blueprint, BMS, BoeringerIngelheim, Celgene, Chugai, Clovis, DaiichiSankyo, Debiopharm, Eisai, Eos, Exelixis, Forma, Gamamabs, Genentech, Gortec, GSK, H3 biomedecine, Incyte, InnatePharma, Janssen, Kura Oncology, Kyowa, Lilly, Loxo, Lysarc, LytixBiopharma, Medimmune, Menarini, Merus, MSD, Nanobiotix, NektarTherapeutics, Novartis, Octimet, Oncoethix, OncopeptidesAB, Orion, Pfizer, Pharmamar, Pierre Fabre, Roche, Sanofi, Servier, Sierra Oncology, Taiho, Takeda, Tesaro and Xencor. J-CS has received consultancy fees from AstraZeneca, Astex, Clovis, GSK, GamaMabs, Lilly, MSD, Mission Therapeutics, Merus, Pfizer, PharmaMar, Pierre Fabre, Roche/Genentech, Sanofi, Servier, Symphogen and Takeda. He has been a full-time employee of MedImmune since September 2017. He is a shareholder of AstraZeneca and Gritstone. CR has acted as a consultant of Amgen, BMS, GSK, Merck, Novartis and Roche. ED has received research grants from Roche, Servier, AstraZeneca, Merck Serono, BMS, MSD, Amgen, Accuray and Boerhinger. He has received personal fees from Roche, AstraZeneca, Merck Serono, Amgen, Accuray and Boerhinger., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Cancer persister cells tolerate anticancer drugs and serve as the founders of acquired resistance and cancer relapse. Here we show that a subpopulation of BRAF V600 mutant melanoma cells that tolerates exposure to BRAF and MEK inhibitors undergoes a reversible remodelling of mRNA translation that evolves in parallel with drug sensitivity. Although this process is associated with a global reduction in protein synthesis, a subset of mRNAs undergoes an increased efficiency in translation. Inhibiting the eIF4A RNA helicase, a component of the eIF4F translation initiation complex, abrogates this selectively increased translation and is lethal to persister cells. Translation remodelling in persister cells coincides with an increased N6-methyladenosine modification in the 5'-untranslated region of some highly translated mRNAs. Combination of eIF4A inhibitor with BRAF and MEK inhibitors effectively inhibits the emergence of persister cells and may represent a new therapeutic strategy to prevent acquired drug resistance.

Objective: Immune checkpoint inhibitors (ICIs) for cancer therapy frequently induce immune-related adverse effects (IRAEs). Therefore, most patients with preexisting autoimmune diseases have been excluded from clinical trials of ICIs. This study was undertaken to evaluate the safety and efficacy of ICIs in patients with preexisting autoimmune disease and cancer., Methods: A retrospective cohort study was conducted from January 2017 to January 2018 via 3 French national networks of experts in oncology and autoimmunity. Adults with preexisting autoimmune disease who were receiving ICIs were assessed for the occurrence of flare of preexisting autoimmune disease, other IRAEs, and cancer response., Results: The study included 112 patients who were followed up for a median of 8 months. The most frequent preexisting autoimmune diseases were psoriasis (n = 31), rheumatoid arthritis (n = 20), and inflammatory bowel disease (n = 14). Twenty-four patients (22%) were receiving immunosuppressive therapy at ICI initiation. Autoimmune disease flare and/or other IRAE(s) occurred in 79 patients (71%), including flare of preexisting autoimmune disease in 53 patients (47%) and/or other IRAE(s) in 47 patients (42%), with a need for immunosuppressive therapy in 48 patients (43%) and permanent discontinuation of ICI in 24 patients (21%). The median progression-free survival was shorter in patients receiving immunosuppressive therapy at ICI initiation (3.8 months versus 12 months; P = 0.006), confirmed by multivariable analysis. The median progression-free survival was shorter in patients who experienced a flare of preexisting autoimmune disease or other IRAE, with a trend toward better survival in the subgroup without immunosuppressant use or ICI discontinuation., Conclusion: Our findings indicate that flares or IRAEs occur frequently but are mostly manageable without ICI discontinuation in patients with a preexisting autoimmune disease. Immunosuppressive therapy at baseline is associated with poorer outcomes., (© 2019, American College of Rheumatology.)

Objective: Expanded clinical experience with patients treated by pembrolizumab has accumulated. However, renal toxicities associated with this anti-programmed cell death 1 agent are poorly described because kidney histology is rarely sought. As a nephrology referral centre, we aimed to describe the clinic-biological and histopathological characteristics of pembrolizumab-related nephropathy and its response to treatment., Methods: We conducted a monocentric large case series study, including all pembrolizumab-treated cancer patients presenting a renal toxicity addressed to our centre from 2015 to 2017., Results: A total of 12 patients (7 men) out of 676 pembrolizumab-treated patients (incidence 1.77%) were included (median age 69.75 years). Patients were referred for acute kidney injury ( n  = 10) and/or proteinuria ( n  = 2). A kidney biopsy was performed in all patients, with a median duration of use of 9 months (range 1-24 months) after the beginning of treatment. Biopsy showed that four patients had acute interstitial nephritis (AIN), whereas five had acute tubular injury (ATI) alone, one had minimal change disease (MCD) and ATI, and one had MCD alone. Pembrolizumab withdrawal coupled with corticosteroid therapy was the most effective treatment for kidney function recovery. Drug reintroduction resulted in a more severe recurrence of AIN in one patient who required maintenance of pembrolizumab. Two patients died of cancer progression with one of them developing severe renal failure requiring dialysis., Conclusion: In our series, ATI, AIN and MCD are the most frequent forms of kidney involvement under pembrolizumab therapy. Kidney dysfunction is usually isolated but can be severe. Use of corticosteroids in case of AIN improves the glomerular filtration rate.

Preventing the immune escape of tumor cells by blocking inhibitory checkpoints, such as the interaction between programmed death ligand-1 (PD-L1) and programmed death-1 (PD-1) receptor, is a powerful anticancer approach. However, many patients do not respond to checkpoint blockade. Tumor PD-L1 expression is a potential efficacy biomarker, but the complex mechanisms underlying its regulation are not completely understood. Here, we show that the eukaryotic translation initiation complex, eIF4F, which binds the 5' cap of mRNAs, regulates the surface expression of interferon-γ-induced PD-L1 on cancer cells by regulating translation of the mRNA encoding the signal transducer and activator of transcription 1 (STAT1) transcription factor. eIF4F complex formation correlates with response to immunotherapy in human melanoma. Pharmacological inhibition of eIF4A, the RNA helicase component of eIF4F, elicits powerful antitumor immune-mediated effects via PD-L1 downregulation. Thus, eIF4A inhibitors, in development as anticancer drugs, may also act as cancer immunotherapies.

Gradients of hypoxia occur in most solid tumors and cells found in hypoxic regions are associated with the most aggressive and therapy-resistant fractions of the tumor. Despite the ubiquity and importance of hypoxia responses, little is known about the variation in the global transcriptional response to hypoxia in melanoma. Using microarray technology, whole genome gene expression profiling was first performed on established melanoma cell lines. From gene set enrichment analyses, we derived a robust 35 probes signature (hypomel for HYPOxia MELanoma) associated with hypoxia-response pathways, including 26 genes up regulated, and 9 genes down regulated. The microarray data were validated by RT-qPCR for the 35 transcripts. We then validated the signature in hypoxic zones from 8 patient specimens using laser microdissection or macrodissection of Formalin fixed-paraffin-embedded (FFPE) material, followed with RT-qPCR. Moreover, a similar hypoxia-associated gene expression profile was observed using NanoString technology to analyze RNAs from FFPE melanoma tissues of a cohort of 19 patients treated with anti-PD1. Analysis of NanoString data from validation sets using Non-Negative Matrix Factorization (NMF) analysis (26 genes up regulated in hypoxia) and dual clustering (samples and genes) further revealed that the increased level of BNIP3 (Bcl-2 adenovirus E1B 19 kDa-interacting protein 3)/GBE1 (glycogen branching enzyme1) differential pair correlates with the lack of response of melanoma patients to anti-PD1 (pembrolizumab) immunotherapy. These studies suggest that through elevated glycogenic flux and induction of autophagy, hypoxia is a critical molecular program that could be considered as a prognostic factor for melanoma., Competing Interests: CONFLICTS OF INTEREST We declare no competing financial interests.

Raman spectroscopy is a noninvasive and label-free optical technique that provides detailed information about the molecular composition of a sample. In this study, we evaluated the potential of Raman spectroscopy to predict skin toxicity due to tyrosine kinase inhibitors treatment. We acquired Raman spectra of skin of patients undergoing treatment with MEK, EGFR, or BRAF inhibitors, which are known to induce severe skin toxicity; for this pilot study, three patients were included for each inhibitor. Our algorithm, based on partial least squares-discriminant analysis (PLS-DA) and cross-validation by bootstrapping, discriminated to variable degrees spectra from patient suffering and not suffering cutaneous adverse events. For MEK and EGFR inhibitors, discriminative power was more than 90% in the viable epidermis skin layer; whereas for BRAF inhibitors, discriminative power was 71%. There was a 81.5% correlation between blood drug concentration and Raman signature of skin in the case of EGFR inhibitors and viable epidermis skin layer. Our results demonstrate the power of Raman spectroscopy to detect apparition of skin toxicity in patients treated with tyrosine kinase inhibitors at levels not detectable via dermatological inspection and histological evaluation. Cancer Res; 77(2); 557-65. ©2016 AACR., (©2016 American Association for Cancer Research.)

Background: Investigations about the impact of dermatologic adverse events on quality of life in the context of targeted therapies are quite recent and results vary in some dimensions. This article aims to summarize the existing data and to clarify needs in terms of clinical management and future research., Methods: A literature review was done with Pubmed, Medline, Scopus and PsycInfo databases and it combined the empirical studies published in English and in French over the past ten years., Results and Conclusions: Dermatologic adverse events globally have a low to moderate impact on quality of life, mainly in the physical and emotional domains. Reasons for inter-individual variations in adjustment and long-term impact are still not well known. Making quality of life assessments systematic, making early referrals of patients to dermatology consultations and giving more attention to individual experience were identified as measures that could help prevent deterioration in quality of life., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

BRAF inhibitors (BRAFi) elicit therapeutic responses in metastatic melanoma, but alarmingly, also induce the formation of secondary benign and malignant skin tumors. Here, we report the emergence and molecular characterization of 73 skin and extracutaneous tumors in 31 patients who underwent BRAFi therapy. The majority of patients presented with classic epidermal tumors such as verrucous papillomas, keratoacanthomas, and squamous cell carcinomas (SCC). However, 15 patients exhibited new or rapidly progressing tumors distinct from these classic subtypes, such as lymph node metastasis, new melanomas, and genital and oral mucosal SCCs. Genotyping of the tumors revealed that oncogenic RAS mutations were found in 58% of the evaluable tumor samples (38/66) and 49% of the control tumors from patients not treated with BRAFi (30/62). Notably, proximity ligation assays demonstrated that BRAF-CRAF heterodimerization was increased in fixed tumor samples from BRAFi-treated patients compared with untreated patients. Our findings reveal that BRAF-CRAF complex formation is significantly associated with BRAFi treatment, and may therefore serve as a useful biomarker of BRAFi-induced cutaneous and extracutaneous tumor formation., (©2016 American Association for Cancer Research.)

In BRAF(V600)-mutant tumours, most mechanisms of resistance to drugs that target the BRAF and/or MEK kinases rely on reactivation of the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signal transduction pathway, on activation of the alternative, PI(3)K-AKT-mTOR, pathway (which is ERK independent) or on modulation of the caspase-dependent apoptotic cascade. All three pathways converge to regulate the formation of the eIF4F eukaryotic translation initiation complex, which binds to the 7-methylguanylate cap (m(7)G) at the 5' end of messenger RNA, thereby modulating the translation of specific mRNAs. Here we show that the persistent formation of the eIF4F complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, is associated with resistance to anti-BRAF, anti-MEK and anti-BRAF plus anti-MEK drug combinations in BRAF(V600)-mutant melanoma, colon and thyroid cancer cell lines. Resistance to treatment and maintenance of eIF4F complex formation is associated with one of three mechanisms: reactivation of MAPK signalling, persistent ERK-independent phosphorylation of the inhibitory eIF4E-binding protein 4EBP1 or increased pro-apoptotic BCL-2-modifying factor (BMF)-dependent degradation of eIF4G. The development of an in situ method to detect the eIF4E-eIF4G interactions shows that eIF4F complex formation is decreased in tumours that respond to anti-BRAF therapy and increased in resistant metastases compared to tumours before treatment. Strikingly, inhibiting the eIF4F complex, either by blocking the eIF4E-eIF4G interaction or by targeting eIF4A, synergizes with inhibiting BRAF(V600) to kill the cancer cells. eIF4F not only appears to be an indicator of both innate and acquired resistance but also is a promising therapeutic target. Combinations of drugs targeting BRAF (and/or MEK) and eIF4F may overcome most of the resistance mechanisms arising in BRAF(V600)-mutant cancers.

Purpose: This phase I study assessed the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), safety, pharmacokinetics, pharmacodynamics, and clinical activity of the first-in-class dual MEK/RAF inhibitor, RO5126766., Experimental Design: Initial dose-escalation was conducted using once daily dosing over 28 consecutive days in 4-week cycles. Further escalation was completed using 2 intermittent dosing schedules [7 days on treatment followed by 7 days off (7on/7off); 4 days on treatment followed by 3 days off (4on/3off)]., Results: Fifty-two patients received RO5126766 at doses of 0.1 to 2.7 mg once daily, 2.7 to 4.0 mg (4 on/3 off), or 2.7 to 5.0 mg (7 on/7 off). The most common DLTs were elevated creatine phosphokinase (CPK) and blurred vision. The MTD for each dosing schedule was 2.25 mg once daily, 4.0 mg (4 on/3 off), and 2.7 mg (7 on/7 off). The dose/schedule recommended for phase II (RP2D) investigation was 2.7 mg (4 on/3 off). Frequent adverse events included rash-related disorders (94.2%), elevated CPK (55.8%), and diarrhea (51.9%). C(max) occurred 1 to 2 hours after dosing and mean terminal half-life was approximately 60 hours. Pharmacodynamic changes included reduced ERK phosphorylation, an increase in apoptosis in tumor tissue, and a reduction in fluorodeoxyglucose (FDG) uptake after 15 days of dosing. Three partial responses were seen: two in BRAF-mutant melanoma tumors and one in an NRAS-mutant melanoma., Conclusion: This first-in-human study shows that oral RO5126766 has manageable toxicity, a favorable pharmacokinetic/pharmacodynamic profile, and encouraging preliminary antitumor activity in this population of heavily pretreated patients, achieving tumor shrinkage in around 40% of patients across all dose levels and all tumor types., (©2012 AACR.)