Alectinib in Resected ALK-Positive Non-Small-Cell Lung Cancer.

BACKGROUND: Platinum-based chemotherapy is the recommended adjuvant treatment for patients with resectable, ALK-positive non-small-cell lung cancer (NSCLC). Data on the efficacy and safety of adjuvant alectinib as compared with chemotherapy in patients with resected ALK-positive NSCLC are lacking. METHODS: We conducted a global, phase 3, open-label, randomized trial in which patients with completely resected, ALK-positive NSCLC of stage IB (tumors ≥4 cm), II, or IIIA (as classified according to the seventh edition of the Cancer Staging Manual of the American Joint Committee on Cancer and Union for International Cancer Control) were randomly assigned in a 1:1 ratio to receive oral alectinib (600 mg twice daily) for 24 months or intravenous platinum-based chemotherapy in four 21-day cycles. The primary end point was disease-free survival, tested hierarchically among patients with stage II or IIIA disease and then in the intention-to-treat population. Other end points included central nervous system (CNS) disease-free survival, overall survival, and safety. RESULTS: In total, 257 patients were randomly assigned to receive alectinib (130 patients) or chemotherapy (127 patients). The percentage of patients alive and disease-free at 2 years was 93.8% in the alectinib group and 63.0% in the chemotherapy group among patients with stage II or IIIA disease (hazard ratio for disease recurrence or death, 0.24; 95% confidence interval [CI], 0.13 to 0.45; P<0.001) and 93.6% and 63.7%, respectively, in the intention-to-treat population (hazard ratio, 0.24; 95% CI, 0.13 to 0.43; P<0.001). Alectinib was associated with a clinically meaningful benefit with respect to CNS disease-free survival as compared with chemotherapy (hazard ratio for CNS disease recurrence or death, 0.22; 95% CI, 0.08 to 0.58). Data for overall survival were immature. No unexpected safety findings were observed. CONCLUSIONS: Among patients with resected ALK-positive NSCLC of stage IB, II, or IIIA, adjuvant alectinib significantly improved disease-free survival as compared with platinum-based chemotherapy. (Funded by F. Hoffmann-La Roche; ALINA ClinicalTrials.gov number, NCT03456076.).

Concordance Between Tissue ALK Detection by Immunohistochemistry and Plasma ALK Detection by Next-Generation Sequencing in the Randomized Phase 3 ALEX Study in Patients With Treatment-Naive Advanced ALK-Positive NSCLC.

Introduction: The Blood First Assay Screening Trial revealed the clinical applicability of blood-based next-generation sequencing to identify patients with ALK-positive NSCLC for alectinib treatment. To understand the relationship between tissue-based versus blood-based testing, we retrospectively investigated concordance between VENTANA ALK (D5F3) CDx immunohistochemistry and the FoundationACT (FACT; Foundation Medicine, Inc.) plasma assay, and compared clinical efficacy between phase 3 ALEX study subpopulations. Methods: Patients with advanced ALK-positive (by immunohistochemistry) NSCLC were randomized 1:1 to alectinib 600 mg or crizotinib 250 mg, twice daily. Assessable baseline plasma samples were analyzed for ALK positivity by FACT; positive percent agreement with immunohistochemistry was evaluated. Progression-free survival (PFS), duration of response, and objective response rate were compared between intention-to-treat (ITT) and biomarker-evaluable populations, and plasma ALK-positive and plasma ALK-negative subpopulations. Results: In the ITT population (303 patients; alectinib, 152; crizotinib, 151), all patients had ALK-positive tumors by immunohistochemistry. In the biomarker-evaluable population (149 patients; alectinib, 76; crizotinib, 73), 105 had plasma ALK-positive and 44 had plasma ALK-negative tumors. Positive percent agreement between immunohistochemistry and FACT was 70.5% (105 of 149; 95% confidence interval: 62.5-77.7). Baseline characteristics were generally balanced, with some exceptions, notably tumor burden. Median PFS in plasma ALK-positive and ALK-negative patients was 22.4 months and not estimable with alectinib and 7.3 months and 12.9 months with crizotinib, respectively; median duration of response was 25.9 months and not estimable with alectinib and 5.6 months and 11.5 months with crizotinib, respectively. Conclusions: Reasonable concordance between FACT and immunohistochemistry was observed; both methods are valuable in identifying ALK-positive patients, separately or concurrently. Alectinib was found to have superior PFS in the plasma ALK-positive population, as in the ITT population.

Circulating Cell-free DNA as a Prognostic Biomarker in Patients with Advanced ALK+ Non-small Cell Lung Cancer in the Global Phase III ALEX Trial.

PURPOSE: We retrospectively assessed prognostic value of circulating cell-free DNA (cfDNA) using data from the phase III ALEX study in treatment-naïve, advanced ALK+ non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients were randomized to receive twice-daily alectinib 600 mg (n = 152) or crizotinib 250 mg (n = 151). cfDNA was quantified from baseline plasma samples, with patients stratified into ≤median and >median cfDNA biomarker-evaluable populations (BEP). Effect of cfDNA concentration on outcomes was analyzed using a Cox regression model with treatment group as covariate, and in multivariate analyses. RESULTS: Median cfDNA concentration in the BEP was 11.53 ng/mL (n = 276). A positive correlation was found between cfDNA concentration and number of lesions, organ lesion sites, and tumor size (sum of longest diameter; all P < 0.0001). In both treatment arms, patients in the >median BEP were more likely to experience disease progression than the ≤median BEP [alectinib adjusted HR = 2.04; 95% confidence interval (CI), 1.07-3.89; P = 0.0305 and crizotinib adjusted HR = 1.83; 95% CI, 1.11-3.00, P = 0.0169]. Median progression-free survival was longer with alectinib than crizotinib in both ≤median and >median BEPs (P < 0.0001). Overall survival data remain immature; survival probability was lower in the >median versus ≤median BEP in both treatment arms (alectinib HR = 2.52; 95% CI, 1.08-5.88; P = 0.0333 and crizotinib HR = 2.63; 95% CI, 1.27-5.47; P = 0.0096). CONCLUSIONS: These data suggest that plasma cfDNA concentration may have prognostic value in advanced ALK+ NSCLC. Prospectively designed studies are warranted to investigate this finding.

Outcomes According to ALK Status Determined by Central Immunohistochemistry or Fluorescence In Situ Hybridization in Patients With ALK-Positive NSCLC Enrolled in the Phase 3 ALEX Study.

INTRODUCTION: We retrospectively examined progression-free survival (PFS) and response by ALK fluorescence in situ hybridization (FISH) status in patients with advanced ALK immunohistochemistry (IHC)-positive NSCLC in the ALEX study. METHODS: A total of 303 treatment-naive patients were randomized to receive twice-daily alectinib 600 mg or crizotinib 250 mg. ALK status was assessed centrally using Ventana ALK (D5F3) CDx IHC and Vysis ALK Break Apart FISH Probe Kit. Primary end point is investigator-assessed PFS. Secondary end points of interest are objective response rate and duration. RESULTS: Investigator-assessed PFS was significantly prolonged with alectinib versus crizotinib in ALK IHC-positive and FISH-positive tumors (n = 203, 67%) (hazard ratio [HR] = 0.37, 95% confidence interval [CI]: 0.25-0.56; p < 0.0001) and ALK IHC-positive and FISH-uninformative tumors (n = 61, 20%) (HR = 0.39, 95% CI: 0.20-0.78) but not in ALK IHC-positive and FISH-negative tumors (n = 39, 13%) (HR = 1.33, 95% CI: 0.6-3.2). Objective response rates were higher with alectinib versus crizotinib in ALK IHC-positive and FISH-positive tumors (90.6% versus 81.4%; stratified OR = 2.22, 95% CI: 0.97-5.07) and ALK IHC-positive and FISH-uninformative tumors (96.0% versus 75.0%; OR = 9.29, 95% CI: 1.05-81.88) but not in ALK IHC-positive and FISH-negative tumors (28.6% versus 44.4%; OR = 0.45, 95% CI: 0.12-1.74). Next-generation sequencing was performed in 35 of 39 patients with ALK IHC-positive and FISH-negative tumors; no ALK fusion was identified in 20 of 35 patients (57.1%) by next-generation sequencing, but 10 of 20 (50.0%) had partial response or stable disease. CONCLUSIONS: Outcomes of patients with ALK IHC-positive and FISH-positive and ALK IHC-positive and FISH-uninformative NSCLC were similar to those of the overall ALEX population. These results suggest that Ventana ALK IHC is a standard testing method for selecting patients for treatment with alectinib.

Outcomes According to ALK Status Determined by Central IHC or FISH in Patients with ALK-Positive NSCLC Enrolled in the Phase III ALEX Study.

INTRODUCTION: We retrospectively examined progression-free survival (PFS) and response by ALK fluorescence in-situ hybridization (FISH) status in patients with advanced ALK immunohistochemistry (IHC)-positive non-small-cell lung cancer (NSCLC) in the ALEX study. METHODS: 303 treatment-naïve patients were randomized to receive twice-daily alectinib 600 mg or crizotinib 250 mg. ALK status was assessed centrally using Ventana ALK (D5F3) CDx IHC and Vysis ALK Break Apart FISH Probe Kit. Primary endpoint: investigator-assessed PFS. Secondary endpoints of interest: objective response rate (ORR) and duration. RESULTS: Investigator-assessed PFS was significantly prolonged with alectinib versus crizotinib in ALK IHC-positive/FISH-positive tumors (n = 203, 67%) (HR 0.37, 95% CI: 0.25-0.56) and ALK IHC-positive/FISH-uninformative tumors (n = 61, 20%) (HR 0.39, 95% CI: 0.20-0.78), but not ALK IHC-positive/FISH-negative tumors (n = 39, 13%) (HR 1.33, 95% CI: 0.6-3.2). ORRs were higher with alectinib versus crizotinib in ALK IHC-positive/FISH-positive tumors 90.6% versus 81.4%; stratified odds ratio [OR] 2.22, 95% CI: 0.97-5.07) and ALK IHC-positive/FISH-uninformative tumors (96.0% versus 75.0%; OR 9.29, 95% CI: 1.05-81.88), but not ALK IHC-positive/FISH-negative tumors (28.6% versus 44.4%; OR 0.45, 95% CI: 0.12-1.74). Next-generation sequencing (NGS) was performed in 35/39 patients with ALK IHC-positive/FISH-negative tumors; no ALK fusion was identified in 20/35 (57.1%) patients by NGS, but 10/20 (50.0%) had partial response/stable disease. CONCLUSION: Outcomes of patients with ALK IHC-positive/FISH-positive and ALK IHC-positive/FISH-uninformative NSCLC were similar to the overall ALEX population. These results suggest that Ventana ALK IHC is a standard testing method for selecting patients for treatment with alectinib.

ALK Mutation Status Before and After Alectinib Treatment in Locally Advanced or Metastatic ALK-Positive NSCLC: Pooled Analysis of Two Prospective Trials.

INTRODUCTION: The effectiveness of ALK receptor tyrosine kinase (ALK) inhibitors can be limited by the development of ALK resistance mutations. This exploratory analysis assessed the efficacy of alectinib in patients with NSCLC and ALK point mutations using pooled data from two single-arm phase II studies. METHODS: Studies NP28673 and NP28761 enrolled adults with locally advanced/metastatic ALK-positive NSCLC who had progressed on crizotinib. ALK mutation analysis was conducted on cell-free DNA from 187 patients post-crizotinib/pre-alectinib, and from 49 of these patients who subsequently progressed on alectinib. RESULTS: Baseline characteristics were generally balanced across patient subgroups. At baseline, 34 distinct ALK mutations were identified in 48 of 187 patients (25.7%). Median investigator-assessed progression-free survival was longer in patients without ALK single-nucleotide variants (n = 138) versus those with (n = 48): 10.2 months (95% confidence interval [CI]: 8.1-14.3) versus 5.6 months (95% CI: 4.5-10.9), respectively. Sixteen of 32 patients (50%) with ALK resistance mutations to crizotinib achieved an investigator-assessed response to alectinib (all partial responses); most of these ALK mutations were known to be sensitive to alectinib. Analysis of plasma samples obtained post-progression on alectinib revealed that 26 of 49 (53%) samples harbored 16 distinct ALK mutations, with known alectinib-resistance mutations, I1171 T/N/S, G1202R, and V1180L, observed in 15 of 49 (31%) tumors. CONCLUSIONS: Alectinib appears clinically active against ALK rearrangements and mutations, as well as several ALK variants that can cause resistance to crizotinib. The use of cell-free DNA in plasma samples may be an alternative noninvasive method for monitoring resistance mutations during therapy.

Updated Efficacy and Safety Data and Impact of the EML4-ALK Fusion Variant on the Efficacy of Alectinib in Untreated ALK-Positive Advanced Non-Small Cell Lung Cancer in the Global Phase III ALEX Study.

INTRODUCTION: At the prior data cutoff (February 9, 2017) the ALEX trial showed superior investigator-assessed progression-free survival (PFS) for alectinib versus crizotinib in untreated, anaplastic lymphoma kinase (ALK)-positive, advanced NSCLC (hazard ratio = 0.47, 95% confidence interval: 0.34-0.65, p < 0.001). The median PFS in the alectinib arm was not reached versus 11.1 months with crizotinib. Retrospective analyses suggest that the echinoderm microtubule-associated protein-like 4 gene-ALK variant (EML4-ALK) may influence ALK-inhibitor treatment benefit. We present updated analyses, including exploratory subgroup analysis by EML4-ALK variant, after an additional 10 months' follow-up (cutoff December 1, 2017). METHODS: Patients were randomized to receive twice-daily alectinib, 600 mg, or crizotinib, 250 mg, until disease progression, toxicity, death, or withdrawal. PFS was determined by the investigators. Baseline plasma and tissue biomarker samples were analyzed by using hybrid-capture, next-generation sequencing to determine EML4-ALK variant. RESULTS: Baseline characteristics were balanced. Investigator-assessed PFS was prolonged with alectinib (stratified hazard ratio = 0.43, 95% confidence interval: 0.32-0.58). The median PFS times were 34.8 months with alectinib and 10.9 months with crizotinib. EML4-ALK fusions were detectable in 129 patient plasma samples and 124 tissue samples; variants 1, 2, and 3/ab did not affect PFS, objective response rate, or duration of response. Investigator-assessed PFS was longer for alectinib than for crizotinib across EML4-ALK variants 1, 2, and 3a/b in plasma and tissue. Despite longer treatment duration (27.0 months in the case of alectinib versus 10.8 months in the case of crizotinib), the safety of alectinib compared favorably with that of crizotinib. CONCLUSION: Alectinib continues to demonstrate superior investigator-assessed PFS versus crizotinib in untreated ALK-positive NSCLC, irrespective of EML4-ALK variant.

HER2 Status in Gastric and Gastroesophageal Junction Cancer: Results of the Large, Multinational HER-EAGLE Study.

Human epidermal growth factor receptor 2 (HER2) dysregulation is associated with tumorigenesis in gastric/gastroesophageal junction cancer; however, the number of patients with HER2-positive disease is unclear, possibly due to differing scoring criteria/assays. Data are also lacking for early disease. We aimed to assess the HER2-positivity rate using approved testing criteria in a large, real-life multinational population. HER2-positivity was defined as an immunohistochemistry staining score of 3+, or immunohistochemistry 2+ and HER2 amplification detected by in situ hybridization. A total of 4949 patients were enrolled and results showed that 14.2% of 4920 samples with immunohistochemistry results were HER2-positive. HER2-positivity was significantly higher in males (16.1% vs. 9.6% in females), in gastroesophageal versus stomach tumors (22.1% vs. 12.9%), in biopsy versus surgical samples (18.3% vs. 13.0%), in intestinal tumor subtypes versus diffuse (21.5% vs. 4.8%) and mixed types (21.5% vs. 8.5%) (P<0.001), in mixed versus diffuse types (8.5% vs. 4.8%), and in "other" versus diffuse types (11.7% vs. 4.8%; P=0.002). There were no significant differences between stages. Patients in the youngest age percentile had significantly lower HER2-positivity rates than patients in the remaining percentiles (9.2% vs. 15.9%, 15.7%, and 15.1%; P<0.001). HER2-positivity was highest in France (20.2%) and lowest in Hong Kong (10.4%). In conclusion, HER-EAGLE, the first study of its kind to be conducted in a large, multinational population of almost 5000 patients, gives valuable insights into the real-world HER2-positivity rate in a gastric/gastroesophageal junction cancer patient population not selected for disease stage or histology.

Alectinib versus Crizotinib in Untreated ALK-Positive Non-Small-Cell Lung Cancer.

BACKGROUND: Alectinib, a highly selective inhibitor of anaplastic lymphoma kinase (ALK), has shown systemic and central nervous system (CNS) efficacy in the treatment of ALK-positive non-small-cell lung cancer (NSCLC). We investigated alectinib as compared with crizotinib in patients with previously untreated, advanced ALK-positive NSCLC, including those with asymptomatic CNS disease. METHODS: In a randomized, open-label, phase 3 trial, we randomly assigned 303 patients with previously untreated, advanced ALK-positive NSCLC to receive either alectinib (600 mg twice daily) or crizotinib (250 mg twice daily). The primary end point was investigator-assessed progression-free survival. Secondary end points were independent review committee-assessed progression-free survival, time to CNS progression, objective response rate, and overall survival. RESULTS: During a median follow-up of 17.6 months (crizotinib) and 18.6 months (alectinib), an event of disease progression or death occurred in 62 of 152 patients (41%) in the alectinib group and 102 of 151 patients (68%) in the crizotinib group. The rate of investigator-assessed progression-free survival was significantly higher with alectinib than with crizotinib (12-month event-free survival rate, 68.4% [95% confidence interval (CI), 61.0 to 75.9] with alectinib vs. 48.7% [95% CI, 40.4 to 56.9] with crizotinib; hazard ratio for disease progression or death, 0.47 [95% CI, 0.34 to 0.65]; P<0.001); the median progression-free survival with alectinib was not reached. The results for independent review committee-assessed progression-free survival were consistent with those for the primary end point. A total of 18 patients (12%) in the alectinib group had an event of CNS progression, as compared with 68 patients (45%) in the crizotinib group (cause-specific hazard ratio, 0.16; 95% CI, 0.10 to 0.28; P<0.001). A response occurred in 126 patients in the alectinib group (response rate, 82.9%; 95% CI, 76.0 to 88.5) and in 114 patients in the crizotinib group (response rate, 75.5%; 95% CI, 67.8 to 82.1) (P=0.09). Grade 3 to 5 adverse events were less frequent with alectinib (41% vs. 50% with crizotinib). CONCLUSIONS: As compared with crizotinib, alectinib showed superior efficacy and lower toxicity in primary treatment of ALK-positive NSCLC. (Funded by F. Hoffmann-La Roche; ALEX ClinicalTrials.gov number, NCT02075840 .).

Role of Troponins I and T and N-Terminal Prohormone of Brain Natriuretic Peptide in Monitoring Cardiac Safety of Patients With Early-Stage Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer Receiving Trastuzumab: A Herceptin Adjuvant Study Cardiac Marker Substudy.

Purpose Women receiving trastuzumab with chemotherapy are at risk for trastuzumab-related cardiac dysfunction (TRCD). We explored the prognostic value of cardiac markers (troponins I and T, N-terminal prohormone of brain natriuretic peptide [NT-proBNP]) to predict baseline susceptibility to develop TRCD. We examined whether development of cardiac end points or significant left ventricular ejection fraction (LVEF) drop was associated with markers' increases. Patients and Methods Cardiac marker assessments were coupled with LVEF measurements at different time points for 533 patients from the Herceptin Adjuvant (HERA) study who agreed to participate in this study. Patients with missing marker assessments were excluded, resulting in 452 evaluable patients. A primary cardiac end point was defined as symptomatic congestive heart failure of New York Heart Association class III or IV, confirmed by a cardiologist, and a significant LVEF drop, or death of definite or probable cardiac causes. A secondary cardiac end point was defined as a confirmed significant asymptomatic or mildly symptomatic LVEF drop. Results Elevated baseline troponin I (> 40 ng/L) and T (> 14 ng/L), occurring in 56 of 412 (13.6%) and 101 of 407 (24.8%) patients, respectively, were associated with an increased significant LVEF drop risk (univariate analysis: hazard ratio, 4.52; P < .001 and hazard ratio, 3.57; P < .001, respectively). Few patients had their first elevated troponin value recorded during the study (six patients for troponin I and 25 patients for troponin T). Two patients developed a primary and 31 patients a secondary cardiac end point (recovery rate of 74%, 23 of 31). For NT-proBNP, higher increases from baseline were seen in patients with significant LVEF drop. Conclusion Elevated troponin I or T before trastuzumab is associated with increased risk for TRCD. A similar conclusion for NT-proBNP could not be drawn because of the lack of a well-established elevation threshold; however, higher increases from baseline were seen in patients with TRCD compared with patients without.

Academia Meets Industry.

Researchers working in industrial laboratories as well as in academic laboratories discussed topics related to the use of extracellular nucleic acids in different fields. These included areas like non-invasive prenatal diagnosis, the application of different methods for the analysis and characterization of patients with benign and malignant diseases and technical aspects associated with extracellular nucleic acids. In addition, the possibilities and chances for a cooperation of researchers working in different worlds, i.e. academia and industry, were discussed.

Assessment of a HER2 scoring system for colorectal cancer: results from a validation study.

We sought to develop criteria for ERBB2-positivity (HER2) in colorectal cancer to ensure accurate identification of ERBB2-amplified metastatic colorectal cancer patients suitable for enrollment in a phase II trial of ERBB2-targeted therapy (HERACLES trial). A two-step approach was used. In step 1, a consensus panel of pathologists adapted existing protocols for use in colorectal cancer to test ERBB2 expression and amplification. Collegial revision of an archival test cohort of colorectal cancer samples led to specific recommendations for adapting current breast and gastric cancer criteria for scoring ERBB2 in colorectal cancer. In step 2, from September 2012 to January 2015, colorectal-specific ERBB2 testing protocols and ERBB2 scoring criteria were used to centrally screen for ERBB2-positive KRAS wild-type colorectal cancer patients to be enrolled in the HERACLES trial (clinical validation cohort). In both archival test (N=256) and clinical validation (N=830) cohorts, a clinically sizeable 5% fraction of KRAS wild-type colorectal cancer patients was found to be ERBB2-positive according to the colorectal cancer-specific ERBB2 scoring criteria. ERBB2-positive tumors showed ERBB2 immunostaining consisting of intense membranous ERBB2 protein expression, corresponding to homogenous ERBB2 amplification, in >50% of cells. None of the immunohistochemistry 0 or 1+ cases was amplified. Concordance between SISH and FISH was 100%. In conclusion, we propose specific criteria for defining ERBB2-positivity in colorectal cancer (HERACLES Diagnostic Criteria). In a phase II trial of trastuzumab and lapatinib in a cetuximab-resistant population, HERACLES Diagnostic Criteria shaped the selection of patients and defined ERBB2 as a predictive marker for response to ERBB2-targeted therapy in metastatic colorectal cancer.

Diverse functional properties of Wilson disease ATP7B variants.

BACKGROUND & AIMS: Wilson disease is a severe disorder of copper metabolism caused by mutations in ATP7B, which encodes a copper-transporting adenosine triphosphatase. The disease presents with a variable phenotype that complicates the diagnostic process and treatment. Little is known about the mechanisms that contribute to the different phenotypes of the disease. METHODS: We analyzed 28 variants of ATP7B from patients with Wilson disease that affected different functional domains; the gene products were expressed using the baculovirus expression system in Sf9 cells. Protein function was analyzed by measuring catalytic activity and copper ((64)Cu) transport into vesicles. We studied intracellular localization of variants of ATP7B that had measurable transport activities and were tagged with green fluorescent protein in mammalian cells using confocal laser scanning microscopy. RESULTS: Properties of ATP7B variants with pathogenic amino-acid substitution varied greatly even if substitutions were in the same functional domain. Some variants had complete loss of catalytic and transport activity, whereas others lost transport activity but retained phosphor-intermediate formation or had partial losses of activity. In mammalian cells, transport-competent variants differed in stability and subcellular localization. CONCLUSIONS: Variants in ATP7B associated with Wilson disease disrupt the protein's transport activity, result in its mislocalization, and reduce its stability. Single assays are insufficient to accurately predict the effects of ATP7B variants the function of its product and development of Wilson disease. These findings will contribute to our understanding of genotype-phenotype correlation and mechanisms of disease pathogenesis.

RAS mutations in cutaneous squamous-cell carcinomas in patients treated with BRAF inhibitors.

BACKGROUND: Cutaneous squamous-cell carcinomas and keratoacanthomas are common findings in patients treated with BRAF inhibitors. METHODS: We performed a molecular analysis to identify oncogenic mutations (HRAS, KRAS, NRAS, CDKN2A, and TP53) in the lesions from patients treated with the BRAF inhibitor vemurafenib. An analysis of an independent validation set and functional studies with BRAF inhibitors in the presence of the prevalent RAS mutation was also performed. RESULTS: Among 21 tumor samples, 13 had RAS mutations (12 in HRAS). In a validation set of 14 samples, 8 had RAS mutations (4 in HRAS). Thus, 60% (21 of 35) of the specimens harbored RAS mutations, the most prevalent being HRAS Q61L. Increased proliferation of HRAS Q61L-mutant cell lines exposed to vemurafenib was associated with mitogen-activated protein kinase (MAPK)-pathway signaling and activation of ERK-mediated transcription. In a mouse model of HRAS Q61L-mediated skin carcinogenesis, the vemurafenib analogue PLX4720 was not an initiator or a promoter of carcinogenesis but accelerated growth of the lesions harboring HRAS mutations, and this growth was blocked by concomitant treatment with a MEK inhibitor. CONCLUSIONS: Mutations in RAS, particularly HRAS, are frequent in cutaneous squamous-cell carcinomas and keratoacanthomas that develop in patients treated with vemurafenib. The molecular mechanism is consistent with the paradoxical activation of MAPK signaling and leads to accelerated growth of these lesions. (Funded by Hoffmann-La Roche and others; ClinicalTrials.gov numbers, NCT00405587, NCT00949702, NCT01001299, and NCT01006980.).

Substrate-dependent drug-drug interactions between gemfibrozil, fluvastatin and other organic anion-transporting peptide (OATP) substrates on OATP1B1, OATP2B1, and OATP1B3.

Hepatic uptake carriers of the organic anion-transporting peptide (OATP) family of solute carriers are more and more recognized as being involved in hepatic elimination of many drugs and potentially associated drug-drug interactions. The gemfibrozil-statin interaction was studied at the level of active hepatic uptake as a model for such drug-drug interactions. Active, temperature-dependent uptake of fluvastatin into primary human hepatocytes was shown. Multiple transporters are involved in this uptake as Chinese hamster ovary or HEK293 cells expressing either OATP1B1 (K(m) = 1.4-3.5 microM), OATP2B1 (K(m) = 0.7-0.8 microM), or OATP1B3 showed significant fluvastatin uptake relative to control cells. For OATP1B1 the inhibition by gemfibrozil was substrate-dependent as the transport of fluvastatin (IC(50) of 63 microM), pravastatin, simvastatin, and taurocholate was inhibited by gemfibrozil, whereas the transport of estrone-3-sulfate and troglitazone sulfate (both used at 3 microM) was not affected. The OATP1B1- but not OATP2B1-mediated transport of estrone-3-sulfate displayed biphasic saturation kinetics, with two distinct affinity components for estrone-3-sulfate (0.23 and 45 microM). Only the high-affinity component was inhibited by gemfibrozil. Recombinant OATP1B1-, OATP2B1-, and OATP1B3-mediated fluvastatin transport was inhibited to 97, 70, and 62% by gemfibrozil (200 microM), respectively, whereas only a small inhibitory effect by gemfibrozil (200 microM) on fluvastatin uptake into primary human hepatocytes was observed (27% inhibition). The results indicate that the in vitro engineered systems can not always predict the behavior in more complex systems such as freshly isolated primary hepatocytes. Therefore, selection of substrate, substrate concentration, and in vitro transport system are critical for the conduct of in vitro interaction studies involving individual liver OATP carriers.

New strategies to address drug-drug interactions involving OATPs.

Pharmacokinetic drug-drug interactions (DDIs) are a major concern in drug development. Drug transport, along with drug metabolism via cytochrome P450s (CYPs), is increasingly being considered as an integral part of the overall pharnmacokinetics profile of a drug. Inhibition of transporters can lead to altered pharmacokinetics, potentially interfering with drug safety and efficacy. There is an increasing number of DDIs observed with statins, which are widely used in combination therapies, and this can be partly attributed to inhibition of individual hepatic transporters. Studies of these inhibitory interactions in vitro has indicated the importance of both hepatic solute carriers of the organic anion transporting polypeptide (OATP) superfamily and CYP inhibition. Mathematical models have been developed to gain more quantitative insights into the interplay between transport and metabolism of drugs. This article reviews new developments in the area of in vitro tools and modeling approaches that are used to study DDIs related to OATP transporters, with a focus on the clinical relevance of the transport-mediated DDIs involving statins.

Functional expression of the canalicular bile salt export pump of human liver.

BACKGROUND & AIMS: Hepatic bile salt secretion is an essential function of vertebrate liver. Rat and mouse bile salt export pump (Bsep) are adenosine triphosphate (ATP)-dependent bile salt transporters. Mutations in human BSEP were identified as the cause of progressive familial intrahepatic cholestasis type 2. BSEP protein is highly identical with its rat and mouse orthologs and has not yet been functionally characterized; the effect of BSEP mutations on its function has also not been studied. Therefore, the aim of this study was to functionally characterize human BSEP. METHODS: Complementary DNA for BSEP was isolated from human liver and expressed with the baculovirus system in Sf9 cells. ATP-dependent bile salt transport assays were performed with Sf9 cell vesicles expressing BSEP and a rapid filtration assay. RESULTS: Cloning of human BSEP required the inactivation of a bacterial cryptic promoter motif within its coding region. BSEP expressed in Sf9 cells transports different bile salts in an ATP-dependent manner with Michaelis constant values as follows: taurocholate, 7.9 +/- 2.1 micromol/L; glycocholate, 11.1 +/- 3.3 micromol/L; taurochenodeoxycholate, 4.8 +/- 1.7 micromol/L; tauroursodeoxycholate, 11.9 +/- 1.8 micromol/L. The rank order of the intrinsic clearance of bile salts was taurochenodeoxycholate > taurocholate > tauroursodeoxycholate > glycocholate. CONCLUSIONS: This study characterizes human BSEP as an ATP-dependent bile salt export pump with transport properties similar to its rat and mouse orthologs. Expression of BSEP in Sf9 cells will enable functional characterization of the consequences of mutations in the human BSEP gene.