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Purpose: The development of resistance limits the clinical benefit of BRAF and MEK inhibitors (BRAFi/MEKi) in BRAFV600-mutated melanoma. It has been shown that short-term treatment (14 days) with vorinostat was able to initiate apoptosis of resistant tumor cells. We aimed to assess the antitumor activity of sequential treatment with vorinostat following BRAFi/MEKi in patients with BRAFV600-mutated melanoma who progressed after initial response to BRAFi/MEKi., Patients and Methods: Patients with BRAFi/MEKi-resistant BRAFV600-mutated melanoma were treated with vorinostat 360 mg once daily for 14 days followed by BRAFi/MEKi. The primary endpoint was an objective response rate of progressive lesions of at least 30% according to Response Evaluation Criteria in Solid Tumors 1.1. Secondary endpoints included progression-free survival, overall survival, safety, pharmacokinetics of vorinostat, and translational molecular analyses using ctDNA and tumor biopsies., Results: Of the 26 patients with progressive BRAFi/MEKi-resistant BRAFV600-mutated melanoma receiving treatment with vorinostat, 22 patients were evaluable for response. The objective response rate was 9%, with one complete response for 31.2 months and one partial response for 14.9 months. Median progression-free survival and overall survival were 1.4 and 5.4 months, respectively. Common adverse events were fatigue (23%) and nausea (19%). ctDNA analysis showed emerging secondary mutations in NRAS and MEK in eight patients at the time of BRAFi/MEKi resistance. Elimination of these mutations by vorinostat treatment was observed in three patients., Conclusions: Intermittent treatment with vorinostat in patients with BRAFi/MEKi-resistant BRAFV600-mutated melanoma is well tolerated. Although the primary endpoint of this study was not met, durable antitumor responses were observed in a minority of patients (9%)., (©2024 American Association for Cancer Research.)

Purpose: We studied EGFR mutations in circulating tumor DNA (ctDNA) and explored their role in predicting the progression-free survival (PFS) of non-small cell lung cancer (NSCLC) patients treated with erlotinib or gefitinib., Methods: The L858R, T790M mutations and exon 19 deletions were quantified in plasma using digital droplet polymerase chain reaction (ddPCR). The dynamics of ctDNA mutations over time and relationships with PFS were explored., Results: In total, 249 plasma samples (1-13 per patient) were available from 68 NSCLC patients. The T790M and L858R or exon 19 deletion were found in the ctDNA of 49 and 56% patients, respectively. The median (range) concentration in these samples were 7.3 (5.1-3688.7), 11.7 (5.1-12,393.3) and 27.9 (5.9-2896.7) copies/mL, respectively. Using local polynomial regression, the number of copies of EGFR mutations per mL increased several months prior to progression on standard response evaluation., Conclusion: This change was more pronounced for the driver mutations than for the resistance mutations. In conclusion, quantification of EGFR mutations in plasma ctDNA was predictive of treatment outcomes in NSCLC patients. In particular, an increase in driver mutation copy number could predict disease progression.

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.

Background: Pimasertib is a selective, potent mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor., Objectives: The aim of this study was to describe the efficacy, safety, and pharmacodynamics of pimasertib at pharmacologically active doses in a cohort of patients with locally advanced/metastatic melanoma from a first-in-human study of pimasertib., Methods: This was a phase I, open-label, two-part, dose-escalation study. Part 1 was conducted in patients with solid tumors and identified the maximum tolerated dose, while Part 2 was restricted to patients with advanced/metastatic melanoma. Endpoints included safety, pharmacodynamics, and antitumor activity. We present data for patients with melanoma only from both parts of the study., Results: In total, 93 patients with melanoma received pimasertib, 89 of whom received pharmacologically active doses (28-255 mg/day) across four dose regimens in the two parts of the study. The objective response rate was 12.4% (11/89): complete response (n = 1) and partial response (PR; n = 10). Six patients responded for > 24 weeks. Nine of the 11 responders had tumors with B-Raf Proto-Oncogene, Serine/Threonine Kinase (BRAF; n = 6) and/or NRAS Proto-Oncogene, GTPase (NRAS; n = 3) mutations. Forty-six patients had stable disease (SD). In patients with ocular melanoma (n = 13), best overall response was PR (n = 1), SD (n = 11), and disease progression (n = 1). Phosphorylated extracellular signal-regulated kinase (pERK) levels were substantially reduced within 2 h of treatment and inhibition was sustained with continuous twice-daily dosing. Treatment-related, recurrent, grade 3 or higher adverse events were reported in eight patients, including diarrhea, and skin and ocular events., Conclusion: Results from this phase I study indicate that pimasertib has clinical activity in patients with locally advanced/metastatic melanoma, particularly BRAF- and NRAS-mutated tumors, at clinically relevant doses associated with pERK inhibition in peripheral blood mononuclear cells., Trial Registration: ClinicalTrials.gov, NCT00982865.

Aim: Pharmacokinetics of small molecule kinase inhibitors (KIs) used in cancer treatment may alter with increasing age, but results are conflicting. This study aims to compare exposure to KIs between older and younger patients (≥70 and <70 years) in clinical practice., Methods: KI plasma concentrations of routinely treated patients were measured using validated assays. Calculated trough concentrations were compared in both age groups. For KIs with a clinically meaningful target concentration (erlotinib, imatinib, pazopanib, sunitinib and vemurafenib), influence of older age on target attainment was assessed., Results: We analysed 616 samples from 454 patients (median age: 61; range 20-93 years), treated with dabrafenib (n = 105), erlotinib (n = 49), imatinib (n = 165), pazopanib (n = 63), sunitinib (n = 87), trametinib (n = 95) and vemurafenib (n = 52). Older age did not significantly influence exposure to erlotinib, imatinib, pazopanib, sunitinib, trametinib and vemurafenib. Elderly patients had significantly higher dabrafenib trough concentrations than younger patients (P = 0.02; 62 ng ml -1 (coefficient of variation [CV] 41%), vs. 53 ng ml -1 (CV 46%), respectively). For KIs with a predefined target concentration, 68% of older and 61% of younger patients reached target., Conclusions: In this real-world study, exposure to most included KIs was comparable in older and younger patients, except for dabrafenib, which showed higher exposure in older patients. In the absence of an absolute target for this KI, clinical relevance remains unclear. For all other included KIs, our data suggest no clinically relevant influence of older age on KI exposure., (© 2018 The British Pharmacological Society.)

Larotrectinib is a promising tyrosine kinase inhibitor for solid tumors harboring tropomyosin receptor kinase gene fusions. A bioanalytical assay was developed for this drug in small volume samples using a 96-well format to efficiently support multiple mouse studies. The assay was completely validated for mouse plasma and partially for homogenates of eight different tissues: brain, heart, kidneys, liver, lungs, small intestine, spleen, and testes. Proteins in 10-μl samples were precipitated using acetonitrile containing momelotinib as internal standard. Chromatographic separation of analyte and internal standard from endogenous interferences was performed on an ethylene bridged octadecyl silica column using 0.1% (v/v) formic acid (in water) and methanol for gradient elution. Electrospray ionization and selected reaction monitoring on a triple quadrupole mass spectrometer were used for detection. In the range 1-2000 ng/ml the drug could be quantified in all 9 matrices with precisions (within-day and between-day) in the range 2.7-11.1% and accuracies in the range 87.4-101.4%. Compounds were sufficiently stable under all investigated conditions except for kidney homogenate. A pilot pharmacokinetic and tissue distribution study in mice demonstrated the applicability of the new presented assay for larotrectinib., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: This phase I, open-label study (Study 1, D3610C00001; NCT01226316) was the first-in-human evaluation of oral AZD5363, a selective pan-AKT inhibitor, in patients with advanced solid malignancies. The objectives were to investigate the safety, tolerability, and pharmacokinetics of AZD5363, define a recommended dosing schedule, and evaluate preliminary clinical activity. Experimental Design: Patients were aged ≥18 years with World Health Organization (WHO) performance status of 0 to 1. Dose escalation was conducted within separate continuous and intermittent [4 days/week (4/7) or 2 days/week (2/7)] schedules with safety, pharmacokinetic, and pharmacodynamic analyses. Expansion cohorts of approximately 20 patients each explored AZD5363 activity in PIK3CA -mutant breast and gynecologic cancers. Results: MTDs were 320, 480, and 640 mg for continuous ( n = 47), 4/7 ( n = 21), and 2/7 ( n = 22) schedules, respectively. Dose-limiting toxicities were rash and diarrhea for continuous, hyperglycemia for 2/7, and none for 4/7. Common adverse events were diarrhea (78%) and nausea (49%) and, for Common Terminology Criteria for Adverse Events grade ≥3 events, hyperglycemia (20%). The recommended phase II dose (480 mg bid, 4/7 intermittent) was assessed in PIK3CA -mutant breast and gynecologic expansion cohorts: 46% and 56% of patients, respectively, showed a reduction in tumor size, with RECIST responses of 4% and 8%. These responses were less than the prespecified 20% response rate; therefore, the criteria to stop further recruitment to the PIK3CA -mutant cohort were met. Conclusions: At the recommended phase II dose, AZD5363 was well tolerated and achieved plasma levels and robust target modulation in tumors. Proof-of-concept responses were observed in patients with PIK3CA -mutant cancers treated with AZD5363. Clin Cancer Res; 24(9); 2050-9. ©2017 AACR See related commentary by Costa and Bosch, p. 2029 ., (©2017 American Association for Cancer Research.)

Although BRAF inhibitor monotherapy yields response rates >50% in BRAF V600 -mutant melanoma, only approximately 5% of patients with BRAF V600E colorectal cancer respond. Preclinical studies suggest that the lack of efficacy in BRAF V600E colorectal cancer is due to adaptive feedback reactivation of MAPK signaling, often mediated by EGFR. This clinical trial evaluated BRAF and EGFR inhibition with dabrafenib (D) + panitumumab (P) ± MEK inhibition with trametinib (T) to achieve greater MAPK suppression and improved efficacy in 142 patients with BRAF V600E colorectal cancer. Confirmed response rates for D+P, D+T+P, and T+P were 10%, 21%, and 0%, respectively. Pharmacodynamic analysis of paired pretreatment and on-treatment biopsies found that efficacy of D+T+P correlated with increased MAPK suppression. Serial cell-free DNA analysis revealed additional correlates of response and emergence of KRAS and NRAS mutations on disease progression. Thus, targeting adaptive feedback pathways in BRAF V600E colorectal cancer can improve efficacy, but MAPK reactivation remains an important primary and acquired resistance mechanism. Significance: This trial demonstrates that combined BRAF + EGFR + MEK inhibition is tolerable, with promising activity in patients with BRAF V600E colorectal cancer. Our findings highlight the MAPK pathway as a critical target in BRAF V600E colorectal cancer and the need to optimize strategies inhibiting this pathway to overcome both primary and acquired resistance. Cancer Discov; 8(4); 428-43. ©2018 AACR. See related commentary by Janku, p. 389 See related article by Hazar-Rethinam et al., p. 417 This article is highlighted in the In This Issue feature, p. 371 ., (©2018 American Association for Cancer Research.)

Background: Epidermal growth factor receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K) are involved in the proliferation and survival of many cancer types. Enhanced antitumor activity may be achieved through combined inhibition of these pathways. We report results for pictilisib (GDC-0941, a class I pan-PI3K inhibitor) plus erlotinib (an EGFR tyrosine kinase inhibitor) in patients with advanced solid tumors., Materials and Methods: A 3 + 3 dose-escalation study was carried out at a starting daily dose of 60 mg pictilisib on days 1-21 of a 28-day cycle and 150 mg erlotinib from day 2 of cycle 1. The primary objectives of the study were to assess safety and tolerability, identify dose-limiting toxicities (DLTs), estimate the maximum tolerated dose, and identify the recommended phase II dose (RP2D). Evaluation of a dose-expansion cohort at the RP2D was performed., Results: Fifty-seven patients were treated in the study. All patients experienced at least one adverse event (AE). Grade ≥3 AEs, serious AEs, and deaths were reported in 38 (66.7%), 19 (33.3%), and 4 (7.0%) patients, respectively. DLTs occurred in nine patients across eight cohorts and the RP2D was determined to be 340 mg pictilisib on a "5 days on, 2 days off" schedule plus 100 mg erlotinib. Two patients (3.5%) experienced partial response and 19 (33.3%) had stable disease., Conclusion: Combining pictilisib with erlotinib in patients with advanced solid tumors is feasible; however, antitumor activity is limited. Additional studies may identify patients likely to benefit from combined inhibition of EGFR and PI3K pathways., Implications for Practice: Combining drugs targeting different signaling pathways in cancer growth and survival could overcome drug resistance and improve antitumor activity. In this first-in-human study for the combination, addition of the PI3K inhibitor pictilisib to the EGFR tyrosine kinase inhibitor erlotinib resulted in toxicity that led to dose and schedule modifications to identify a tolerable recommended phase II dose of 340 mg pictilisib on a "5 days on, 2 days off" schedule plus 100 mg erlotinib daily. The limited antitumor activity observed, however, suggests that additional studies are needed to identify patients most likely to benefit from combined EGFR and PI3K inhibition., Competing Interests: Disclosures of potential conflicts of interest may be found at the end of this article., (© AlphaMed Press 2017.)

Despite the fact that pharmacokinetic exposure of kinase inhibitors (KIs) is highly variable and clear relationships exist between exposure and treatment outcomes, fixed dosing is still standard practice. This review aims to summarize the available clinical pharmacokinetic and pharmacodynamic data into practical guidelines for individualized dosing of KIs through therapeutic drug monitoring (TDM). Additionally, we provide an overview of prospective TDM trials and discuss the future steps needed for further implementation of TDM of KIs., (© 2017 The Authors Clinical Pharmacology & Therapeutics published by Wiley Periodicals, Inc. on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Introduction: Paediatric dose-finding studies are challenging to perform due to ethical reasons, the limited number of available patients and restricted number of blood samples. In certain cases, the adult pharmacokinetic (PK) exposure can be used as target for dose finding in paediatrics. The aim of this study was to investigate the performance of a paediatric phase I dose-finding clinical trial in silico., Methods: Using an adult pharmacokinetic model, clinical trial simulations were performed to determine the power of a proposed clinical trial design. Power was defined as the fraction of 1000 trials with an area under the plasma concentration-time curve at steady-state (AUC 0-24,SS ) within ±20% of the adult geometric mean AUC 0-24,SS . Different scenarios were compared to optimise the design of the trial. To show the potential of this framework for similar compounds, the current simulation method was also evaluated with adult and paediatric data from literature on sunitinib., Results: At the starting dose of 300 mg/m 2 , the power of the trial design was 66.9%. Power did not improve by dose escalation to 350 mg/m 2 (65.3%). Power increased to 78.9% with inclusion of 10 patients per trial. Paediatric sunitinib PK data were adequately predicted from adult data with a mean prediction error of 1.80%., Conclusion: The performance of PK-based clinical trials in paediatrics can be predicted and optimised through PK modelling and simulation. Application of this approach enables clinical trials in paediatrics to be performed as efficiently as possible while protecting the child from unnecessary harm., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A bioanalytical assay for quizartinib -a potent, and selective FLT3 tyrosine kinase inhibitor- in mouse plasma was developed and validated. Salting-out assisted liquid-liquid extraction (SALLE), using acetonitrile and magnesium sulfate, was selected as sample pretreatment with deuterated quizartinib as internal standard. Separation was performed with reversed-phase liquid chromatography followed by detection with positive electrospray-triple quadrupole mass spectrometry in the selected reaction monitoring mode. The assay was successfully validated for mouse plasma in a 2-2000ng/ml calibration range with r 2 =0.9958±0.0028 (n=7) for linear regression with the inverse square of the concentration as a weighting factor. The within-run precision (n=18), between-run precision and accuracy were 2.9-6.0%, 4.5-8.9% and 91.7-109.4% respectively. The drug was stable under all relevant conditions. Finally, the assay was successfully applied in a pharmacokinetic pilot study in plasma of FVB/NRj mice treated with quizartinb orally., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Purpose AKT1 E17K mutations are oncogenic and occur in many cancers at a low prevalence. We performed a multihistology basket study of AZD5363, an ATP-competitive pan-AKT kinase inhibitor, to determine the preliminary activity of AKT inhibition in AKT-mutant cancers. Patients and Methods Fifty-eight patients with advanced solid tumors were treated. The primary end point was safety; secondary end points were progression-free survival (PFS) and response according to Response Evaluation Criteria in Solid Tumors (RECIST). Tumor biopsies and plasma cell-free DNA (cfDNA) were collected in the majority of patients to identify predictive biomarkers of response. Results In patients with AKT1 E17K-mutant tumors (n = 52) and a median of five lines of prior therapy, the median PFS was 5.5 months (95% CI, 2.9 to 6.9 months), 6.6 months (95% CI, 1.5 to 8.3 months), and 4.2 months (95% CI, 2.1 to 12.8 months) in patients with estrogen receptor-positive breast, gynecologic, and other solid tumors, respectively. In an exploratory biomarker analysis, imbalance of the AKT1 E17K-mutant allele, most frequently caused by copy-neutral loss-of-heterozygosity targeting the wild-type allele, was associated with longer PFS (hazard ratio [HR], 0.41; P = .04), as was the presence of coincident PI3K pathway hotspot mutations (HR, 0.21; P = .045). Persistent declines in AKT1 E17K in cfDNA were associated with improved PFS (HR, 0.18; P = .004) and response ( P = .025). Responses were not restricted to patients with detectable AKT1 E17K in pretreatment cfDNA. The most common grade ≥ 3 adverse events were hyperglycemia (24%), diarrhea (17%), and rash (15.5%). Conclusion This study provides the first clinical data that AKT1 E17K is a therapeutic target in human cancer. The genomic context of the AKT1 E17K mutation further conditioned response to AZD5363.

Preclinical evidence suggests that concomitant BRAF and EGFR inhibition leads to sustained suppression of MAPK signaling and suppressed tumor growth in BRAF V600E colorectal cancer models. Patients with refractory BRAF V600 -mutant metastatic CRC (mCRC) were treated with a selective RAF kinase inhibitor (encorafenib) plus a monoclonal antibody targeting EGFR (cetuximab), with ( n = 28) or without ( n = 26) a PI3Kα inhibitor (alpelisib). The primary objective was to determine the maximum tolerated dose (MTD) or a recommended phase II dose. Dose-limiting toxicities were reported in 3 patients receiving dual treatment and 2 patients receiving triple treatment. The MTD was not reached for either group and the phase II doses were selected as 200 mg encorafenib (both groups) and 300 mg alpelisib. Combinations of cetuximab and encorafenib showed promising clinical activity and tolerability in patients with BRAF -mutant mCRC; confirmed overall response rates of 19% and 18% were observed and median progression-free survival was 3.7 and 4.2 months for the dual- and triple-therapy groups, respectively. Significance: Herein, we demonstrate that dual- (encorafenib plus cetuximab) and triple- (encorafenib plus cetuximab and alpelisib) combination treatments are tolerable and provide promising clinical activity in the difficult-to-treat patient population with BRAF -mutant mCRC. Cancer Discov; 7(6); 610-9. ©2017 AACR. See related commentary by Sundar et al., p. 558 This article is highlighted in the In This Issue feature, p. 539 ., (©2017 American Association for Cancer Research.)

In recent years (2010-present) there has been an increase in the number of publications reporting the development, validation and use of bioanalytical methods in the rapidly expanding drug class of small molecule protein kinase inhibitors. Most reports describe the technological set-up of the methods that have allowed for drug concentration measurements from various sample types. This includes plasma, dried blood-spot, and tissue-analysis. Also method development, exploration of various techniques, as well as measurement and identification of metabolites were addressed. For the bioanalysis, a variety of sample-pretreatment methods like protein-precipitation, liquid-liquid extraction, and solid-phase extraction have been employed, all varying in complexity, cleanliness and time-consumption. Chromatographic separation, nowadays, is more focused on separating components from ion-suppressive effects, since for MS/MS detection, various components do not have to be baseline separated. For detection multiple types of detectors were used, ranging from state-of-the-art high resolution, and tandem mass spectrometry with low picogram per milliliter detection limits to the classical UV-detector with several nanograms per milliliter limits. As new bioanalytical methods have arisen that do rely on chromatographic separation, for example for high-throughput analysis, these are addressed in this review as well., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Membrane transporters are key determinants of therapeutic outcomes. They regulate systemic and cellular drug levels influencing efficacy as well as toxicities. Here we report a unique phosphorylation-dependent interaction between drug transporters and tyrosine kinase inhibitors (TKIs), which has uncovered widespread phosphotyrosine-mediated regulation of drug transporters. We initially found that organic cation transporters (OCTs), uptake carriers of metformin and oxaliplatin, were inhibited by several clinically used TKIs. Mechanistic studies showed that these TKIs inhibit the Src family kinase Yes1, which was found to be essential for OCT2 tyrosine phosphorylation and function. Yes1 inhibition in vivo diminished OCT2 activity, significantly mitigating oxaliplatin-induced acute sensory neuropathy. Along with OCT2, other SLC-family drug transporters are potentially part of an extensive 'transporter-phosphoproteome' with unique susceptibility to TKIs. On the basis of these findings we propose that TKIs, an important and rapidly expanding class of therapeutics, can functionally modulate pharmacologically important proteins by inhibiting protein kinases essential for their post-translational regulation.