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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.

Purpose AZD1775 is a WEE1 kinase inhibitor targeting G2 checkpoint control, preferentially sensitizing TP53-deficient tumor cells to DNA damage. This phase I study evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of oral AZD1775 as monotherapy or in combination with chemotherapy in patients with refractory solid tumors. Patients and Methods In part 1, patients received a single dose of AZD1775 followed by 14 days of observation. In part 2, patients received AZD1775 as a single dose (part 2A) or as five twice per day doses or two once per day doses (part 2B) in combination with one of the following chemotherapy agents: gemcitabine (1,000 mg/m 2 ), cisplatin (75 mg/m 2 ), or carboplatin (area under the curve, 5 mg/mL⋅min). Skin biopsies were collected for pharmacodynamic assessments. TP53 status was determined retrospectively in archival tumor tissue. Results Two hundred two patients were enrolled onto the study, including nine patients in part 1, 43 in part 2A (including eight rollover patients from part 1), and 158 in part 2B. AZD1775 monotherapy given as single dose was well tolerated, and the maximum-tolerated dose was not reached. In the combination regimens, the most common adverse events consisted of fatigue, nausea and vomiting, diarrhea, and hematologic toxicity. The maximum-tolerated doses and biologically effective doses were established for each combination. Target engagement, as a predefined 50% pCDK1 reduction in surrogate tissue, was observed in combination with cisplatin and carboplatin. Of 176 patients evaluable for efficacy, 94 (53%) had stable disease as best response, and 17 (10%) achieved a partial response. The response rate in TP53-mutated patients (n = 19) was 21% compared with 12% in TP53 wild-type patients (n = 33). Conclusion AZD1775 was safe and tolerable as a single agent and in combination with chemotherapy at doses associated with target engagement.

Purpose AZD1775 is a first-in-class, potent, and selective inhibitor of WEE1 with proof of chemopotentiation in p53-deficient tumors in preclinical models. In a phase I study, the maximum tolerated dose of AZD1775 in combination with carboplatin demonstrated target engagement. We conducted a proof-of-principle phase II study in patients with p53 tumor suppressor gene ( TP53)-mutated ovarian cancer refractory or resistant (< 3 months) to first-line platinum-based therapy to determine overall response rate, progression-free and overall survival, pharmacokinetics, and modulation of phosphorylated cyclin-dependent kinase (CDK1) in skin biopsies. Patients and Methods Patients were treated with carboplatin (area under the curve, 5 mg/mL⋅min) combined with AZD1775 225 mg orally twice daily over 2.5 days every 21-day cycle until disease progression. Results AZD1775 plus carboplatin demonstrated manageable toxicity; fatigue (87%), nausea (78%), thrombocytopenia (70%), diarrhea (70%), and vomiting (48%) were the most common adverse events. The most frequent grade 3 or 4 adverse events were thrombocytopenia (48%) and neutropenia (37%). Of 24 patients enrolled, 21 patients were evaluable for efficacy end points. The overall response rate was 43% (95% CI, 22% to 66%), including one patient (5%) with a prolonged complete response. Median progression-free and overall survival times were 5.3 months (95% CI, 2.3 to 9.0 months) and 12.6 months (95% CI, 4.9 to 19.7), respectively, with two patients with ongoing response for more than 31 and 42 months at data cutoff. Conclusion To our knowledge, this is the first report providing clinical proof that AZD1775 enhances carboplatin efficacy in TP53-mutated tumors. The encouraging antitumor activity observed in patients with TP53-mutated ovarian cancer who were refractory or resistant (< 3 months) to first-line therapy warrants further development.

Aims: The enzymatic activity of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are important for the tolerability and efficacy of the fluoropyrimidine drugs. In the present study, we explored between-subject variability (BSV) and circadian rhythmicity in DPD and TS activity in human volunteers., Methods: The BSVs in DPD activity (n = 20) in peripheral blood mononuclear cells (PBMCs) and in plasma, measured by means of the dihydrouracil (DHU) and uracil (U) plasma levels and DHU : U ratio (n = 40), and TS activity in PBMCs (n = 19), were examined. Samples were collected every 4 h throughout 1 day for assessment of circadian rhythmicity in DPD and TS activity in PBMCs (n = 12) and DHU : U plasma ratios (n = 23). In addition, the effects of genetic polymorphisms and gene expression on DPD and TS activity were explored., Results: Population mean (± standard deviation) DPD activity in PBMCs and DHU : U plasma ratio were 9.2 (±2.1) nmol mg(-1) h(-1) and 10.6 (±2.4), respectively. Individual TS activity in PBMCs ranged from 0.024 nmol mg(-1) h(-1) to 0.596 nmol mg(-1) h(-1) . Circadian rhythmicity was demonstrated for all phenotype markers. Between 00:30 h and 02:00 h, DPD activity in PBMCs peaked, while the DHU : U plasma ratio and TS activity in PBMCs showed trough activity. Peak-to-trough ratios for DPD and TS activity in PBMCs were 1.69 and 1.62, respectively. For the DHU : U plasma ratio, the peak-to-trough ratio was 1.43., Conclusions: BSV and circadian variability in DPD and TS activity were demonstrated. Circadian rhythmicity in DPD might be tissue dependent. The results suggested an influence of circadian rhythms on phenotype-guided fluoropyrimidine dosing and supported implications for chronotherapy with high-dose fluoropyrimidine administration during the night., (© 2016 The British Pharmacological Society.)

Although recent clinical trials of BRAF inhibitor combinations have demonstrated improved efficacy in BRAF-mutant colorectal cancer, emergence of acquired resistance limits clinical benefit. Here, we undertook a comprehensive effort to define mechanisms underlying drug resistance with the goal of guiding development of therapeutic strategies to overcome this limitation. We generated a broad panel of BRAF-mutant resistant cell line models across seven different clinically relevant drug combinations. Combinatorial drug treatments were able to abrogate ERK1/2 phosphorylation in parental-sensitive cells, but not in their resistant counterparts, indicating that resistant cells escaped drug treatments through one or more mechanisms leading to biochemical reactivation of the MAPK signaling pathway. Genotyping of resistant cells identified gene amplification of EGFR, KRAS, and mutant BRAF, as well as acquired mutations in KRAS, EGFR, and MAP2K1 These mechanisms were clinically relevant, as we identified emergence of a KRAS G12C mutation and increase of mutant BRAF V600E allele frequency in the circulating tumor DNA of a patient at relapse from combined treatment with BRAF and MEK inhibitors. To identify therapeutic combinations capable of overcoming drug resistance, we performed a systematic assessment of candidate therapies across the panel of resistant cell lines. Independent of the molecular alteration acquired upon drug pressure, most resistant cells retained sensitivity to vertical MAPK pathway suppression when combinations of ERK, BRAF, and EGFR inhibitors were applied. These therapeutic combinations represent promising strategies for future clinical trials in BRAF-mutant colorectal cancer. Cancer Res; 76(15); 4504-15. ©2016 AACR., (©2016 American Association for Cancer Research.)

Herein we describe a case of a 62-year-old female in good clinical condition with non-small-cell lung cancer who was treated with crizotinib. After 24 days of crizotinib therapy she presented with acute liver failure. Serum aspartate aminotransferase and alanine aminotransferase levels had increased from normal prior to crizotinib start to 2053 IU/L and 6194 IU/L, respectively. Total bilirubin and prothrombin time (PT-INR) increased up to 443 IU/L and 5.33, respectively, and symptoms of hepatic encephalopathy and hepatorenal syndrome emerged. Despite crizotinib discontinuation and intensive supportive therapy, the patient died 40 days after treatment with crizotinib was initiated due to acute liver failure with massive liver cell necrosis., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: Dihydropyrimidine dehydrogenase (DPD) activity determination in peripheral blood mononuclear cells of DPD deficient patients was hitherto inaccurate due to hemoglobin (Hb) contamination. We developed an improved method for accurate measurement of DPD activity in patients., Results: DPD activity was determined by HPLC with online radioisotope detection using liquid scintillation counting. Hb was determined spectrophotometrically. Method accuracy and precision were significantly improved by using cumulative area of all peaks as IS. Peripheral blood mononuclear cell lysates from DPD deficient patients were highly contaminated with on average 23.3% (range 2.7-51%) of Hb resulting in up to twofold underestimated DPD activity. DPD activities were corrected for Hb contamination. The method was validated and showed good long-term sample stability., Conclusion: This method has increased specificity allowing accurate identification of DPD deficient patients.

Colorectal cancer has been characterized as a genetically heterogeneous disease, with a large diversity in molecular pathogenesis resulting in differential responses to therapy. However, the currently available validated biomarkers KRAS, BRAF, and microsatellite instability do not sufficiently cover this extensive heterogeneity and are therefore not suitable to successfully guide personalized treatment. Recent studies have focused on novel targets and rationally designed combination strategies. Furthermore, a more comprehensive analysis of the underlying biology of the disease revealed distinct phenotypic differences within subgroups of patients harboring the same genetic driver mutation with both prognostic and predictive relevance. Accordingly, patient stratification based on molecular intrinsic subtypes rather than on single gene aberrations holds promise to improve the clinical outcome of patients with colorectal cancer.

Pazopanib and axitinib are both U.S. Food and Drug Administration approved ATP-competitive inhibitors of the vascular endothelial growth factor receptor. Pazopanib and axitinib have been shown to be effective and tolerable treatment options for patients with metastatic renal cell cancer and therefore have enlarged the armamentarium for this disease. This concise drug review discusses the clinical benefits, clinical use, mechanism of action, bioanalysis, pharmacokinetics, pharmacogenetics, pharmacodynamics, drug resistance, toxicity, and patient instructions and recommendations for supportive care for these two drugs.