The Impact of Dose and Simultaneous Use of Acid-Reducing Agents on the Effectiveness of Vemurafenib in Metastatic BRAF V600 Mutated Melanoma: a Retrospective Cohort Study.

BACKGROUND: The impact of dose and simultaneous use of acid-reducing agents (ARAs) on the effectiveness of vemurafenib is unknown. OBJECTIVES: To determine the association between progression of metastatic BRAF V600 mutated melanoma and (1) dose reductions of vemurafenib and (2) simultaneous use of vemurafenib and ARAs. PATIENT AND METHODS: A retrospective cohort study of 112 first-line vemurafenib users for melanoma was conducted (March 2012-March 2016), using electronic patient records and pharmacy dispensing records of a Dutch academic hospital. Cox regression analysis was used to estimate the risk of progression with full-dose (n = 64) versus reduced-dose vemurafenib (n = 48) and with simultaneous use of vemurafenib and ARAs (n = 35) versus vemurafenib alone (n = 77). Analyses were adjusted for age and sex. RESULTS: In total, disease progression occurred in 55% of treated patients on vemurafenib, with a median progression-free survival of 6.0 (95% confidence interval [CI] 5.0-6.9) months. Compared to patients on vemurafenib alone, there was no increased risk of progression among patients requiring vemurafenib at a reduced dose or among patients receiving simultaneous therapy with vemurafenib and ARAs. In addition, there was no increased risk of progression among patients who used reduced-dose vemurafenib and ARAs versus those receiving full-dose vemurafenib as sole therapy. However, a tendency for progression was observed among patients who used full-dose vemurafenib and ARAs versus full-dose vemurafenib alone (adjusted hazard ratio [HRa] 2.37; 95% CI 0.97-5.76), which became statistically significant in a sensitivity analysis (HRa 4.56; 95% CI 1.51-13.75). CONCLUSIONS: There was no association between the use of vemurafenib in a reduced dose or the simultaneous use of vemurafenib and ARAs and the risk of progression. In addition, there was no association between the simultaneous use of vemurafenib in a reduced dose and ARAs and the risk of progression. However, patients tolerating  full-dose vemurafenib simultaneously with ARAs might have an increased risk of progression. This finding requires prospective validation.

Development and validation of an analytical method using UPLC-MS/MS to quantify everolimus in dried blood spots in the oncology setting.

While the therapeutic drug monitoring (TDM) of everolimus has been routinely performed for over 10 years in solid organ transplantation medicine, in order to optimize the balance between effectiveness and toxicity, it is yet uncommon in the treatment of malignancies. The aim of this study was to develop and validate a bioanalytical method to quantify everolimus in dried blood spots (DBS) to facilitate TDM for the oncology outpatient setting. The hematocrit effect of everolimus was investigated. An 7.5mm disk from the central part of the DBS was punched, followed by the extraction of everolimus from the DBS by methanol/acetonitrile (80/20%) spiked with deuterium-labelled everolimus as internal standard. Subsequently, everolimus was separated and analyzed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The UPLC-MS/MS method was validated according to the European Medicine Agency (EMA) guideline. Everolimus concentrations could be quantified over the range of 3-75µg/L. The intra- and inter-assay precision and accuracy of the method were shown to be acceptable (coefficient of variation ≤10.7% and relative error ≤4.4%, respectively). The matrix effects appeared to be influenced by the hematocrit effect. The hematocrit effect was tested in a range of 0.20-0.50L/L, at which hematocrit accuracy and precision were satisfactory at values ≥0.25L/L. However, at 0.20L/L hematocrit in combination with high everolimus concentrations of 20 and 40µg/L, the precision was adequate (≤7.4%), but the accuracy was >15% of the nominal concentration. Everolimus was stable in DBS for at least 80days at 2-8°C. Given these results, the everolimus DBS method has been successfully developed and validated. Special attention is necessary for cancer patients with both a 0.20L/L hematocrit in combination with everolimus concentrations ≥20µg/L. A clinical validation for the use of everolimus DBS in cancer patients is currently being undertaken.

Use of incretin agents and risk of acute and chronic pancreatitis: A population-based cohort study.

AIM: To determine the association between the use of incretin agents (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists) for the treatment of type 2 diabetes mellitus (T2DM) and the risk of any, acute and chronic pancreatitis. RESEARCH DESIGN AND METHODS: A population-based cohort study was conducted using data from the UK Clinical Practice Research Datalink (CPRD 2007-2012). A total of 182 428 adult patients with ≥1 non-insulin antidiabetic drug (NIAD) prescription were matched to control subjects without diabetes. Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of pancreatitis in incretin-users (N = 28 370) compared with controls and with other NIAD users. Adjustments were made for lifestyle, disease and drug history. In a sensitivity analysis, a new-user design was used. RESULTS: Current incretin users had a 1.5-fold increased risk of any pancreatitis compared with NIAD users (adjusted HR 1.47, 95% CI 1.06-2.04). In incident current incretin users the risk of any and acute pancreatitis was increased 2.1- and 2.0-fold compared with NIAD users (adjusted HR 2.12, 95% CI 1.31-3.43 and adjusted HR 1.96, 95% CI 1.13-3.41), whereas there was no increased risk found for chronic pancreatitis. CONCLUSIONS: Incretin use was associated with an increased risk of any pancreatitis. Moreover, risk of any and acute pancreatitis was higher when applying a new-user design. We were not able to detect an association with chronic pancreatitis, but the number in this subgroup was small.

Plasma concentrations of tyrosine kinase inhibitors imatinib, erlotinib, and sunitinib in routine clinical outpatient cancer care.

BACKGROUND: The objectives of this study were to evaluate the plasma concentrations of the tyrosine kinase inhibitors (TKIs), imatinib, erlotinib, and sunitinib, in a cohort of patients with cancer in routine clinical practice and to find the possible factors related to plasma concentrations below the target level. METHODS: An observational study was performed in an unselected cohort of patients using TKIs for cancer treatment. Randomly timed plasma samples were drawn together with regular laboratory investigations during routine outpatient clinic visits. The plasma concentrations of TKIs were determined using a validated high-performance liquid chromatography coupled with tandem mass spectrometry detection method. Trough concentrations were estimated using the interval between the last dose intake and blood sampling and the mean elimination half-life of the TKIs and were compared with target trough concentrations. Outpatient medical records were reviewed to collect data on patient- and medication-related factors that could have contributed to the variation in TKI plasma concentrations. RESULTS: Only 26.8%, 88.9%, and 51.4% of the calculated trough plasma concentrations of imatinib, erlotinib, and sunitinib samples, respectively, reached the predefined target concentration (imatinib: 1100 ng/mL, erlotinib: 500 ng/mL, and sunitinib: 50 ng/mL). Interpatient variability was high with coefficients of variation of 39.1%, 40.1%, and 29.2% for imatinib, erlotinib, and sunitinib, respectively. High variation in plasma concentrations could only partly be explained by patient- or medication related factors. CONCLUSIONS: Almost half of the plasma concentrations in the outpatient population seemed to be below the target level with a risk of treatment failure. It is not possible to predict which patients are at a risk of plasma concentrations below the target level based on patient- or medication-related factors. Thus, therapeutic drug monitoring could play a crucial role in routine cancer care to identify patients that are in need of individual adjusted dosages. Further research is required to investigate the safety and efficacy of therapeutic drug monitoring.

Use of biguanides and the risk of colorectal cancer: a register-based cohort study.

Observational studies have shown conflicting results on the potential protecting effect of biguanide use with the risk of colorectal neoplasms. In addition, the cellular mechanism can either support or oppose biguanides influence on colorectal carcinoma. Our objective was to evaluate the association between biguanide use and colorectal carcinoma. A population-based cohort study using healthcare data from the Danish National database (1996-2007), was conducted. Oral antidiabetic drug users (n = 177,281) were matched 1:3 with a population-based reference group. Cox proportional hazard models estimated hazard ratios (HRs) of colorectal carcinoma. Stratification was performed to analyse the risk of colorectal cancer in current biguanide users. Two sub-analyses were performed, to investigate the risk of colorectal cancer associated with discontinuous and prolonged use of biguanides. Instead of a protective effect, we found that current biguanide users had a 1.2-fold increased risk of colorectal cancer (HR = 1.19, 95% CI = 1.08-1.30) as compared with the non-diabetes reference group. Prolonged use was not inversely associated with colorectal cancer either. When studying colorectal risk with biguanides, the underlying T2DM should be taken into account since a 1.3-1.6-fold increased risk was found in oral antidiabetic drug users compared to controls unexposed to diabetic medication. This study could not detect a protective effect of biguanide use with colorectal cancer. Therefore, this study does not support a further investigation of the effectiveness of biguanides to prevent colorectal carcinoma in clinical studies.