Fluoropyrimidine type, patient age, tumour sidedness and mutation status as determinants of benefit in patients with metastatic colorectal cancer treated with EGFR monoclonal antibodies: individual patient data pooled analysis of randomised trials from the ARCAD database.

BACKGROUND: KRAS mutations in metastatic colorectal cancer (mCRC) are used as predictive biomarkers to select therapy with EGFR monoclonal antibodies (mAbs). Other factors may be significant determinants of benefit. METHODS: Individual patient data from randomised trials with a head-to-head comparison between EGFR mAb versus no EGFR mAb (chemotherapy alone or best supportive care) in mCRC, across all lines of therapy, were pooled. Overall survival (OS) and progression-free survival (PFS) were compared between groups. Treatment effects within the predefined KRAS biomarker subsets were estimated by adjusted hazard ratio (HRadj) and 95% confidence interval (CI). EGFR mAb efficacy was measured within the KRAS wild-type subgroup according to BRAF and NRAS mutation status. In both KRAS wild-type and mutant subgroups, additional factors that could impact EGFR mAb efficacy were explored including the type of chemotherapy, line of therapy, age, sex, tumour sidedness and site of metastasis. RESULTS: 5675 patients from 8 studies were included, all with known mCRC KRAS mutation status. OS (HRadj 0.90, 95% CI 0.84-0.98, p = 0.01) and PFS benefit (HRadj 0.73, 95% CI 0.68-0.79, p < 0.001) from EGFR mAbs was observed in the KRAS wild-type group. PFS benefit was seen in patients treated with fluorouracil (HRadj 0.75, 95% CI 0.68-0.82) but not with capecitabine-containing regimens (HRadj 1.04, 95% CI 0.86-1.26) (pinteraction = 0.002). Sidedness also interacted with EGFR mAb efficacy, with survival benefit restricted to left-sided disease (pinteraction = 0.038). PFS benefits differed according to age, with benefits greater in those under 70 (pinteraction = 0.001). The survival benefit was not demonstrated in those patients with mutations found in the KRAS, NRAS or BRAF genes. The presence of liver metastases interacted with EGFR mAb efficacy in patients with KRAS mutant mCRC (pinteraction = 0.004). CONCLUSION: The benefit provided by EGFR mAbs in KRAS WT mCRC is associated with left-sided primary tumour location, younger patient age and absence of NRAS or BRAF mutations. Survival benefit is observed with fluorouracil but not capecitabine. Exploratory results support further research in KRAS mutant mCRC without liver metastases.

Patient-reported outcomes predict survival and adverse events following anticancer treatment initiation in advanced HER2-positive breast cancer.

BACKGROUND: The prognostic value of patient-reported outcomes (PROs) has been minimally explored in advanced breast cancer (BC), and their comparative prognostic performance against Eastern Cooperative Oncology Group performance status (ECOG PS) is largely unknown. PATIENTS AND METHODS: This study pooled individual participant data from clinical trials CLEOPATRA, EMILIA, and MARIANNE. Pre-treatment PRO associations with overall survival (OS), progression-free survival (PFS), and grade ≥3 adverse events were evaluated via Cox proportional hazards regression. Prognostic performance was assessed with the C-statistic (c). PRO values were collected via the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire. All analyses were stratified by study and treatment arms. Analyses adjusted for known prognostic variables were conducted. Exploratory analysis of the prognostic performance of PROs compared to ECOG PS was undertaken. RESULTS: The study included data from 2894 patients initiated on contemporary therapies including pertuzumab (n = 765), trastuzumab (n = 1173), trastuzumab emtansine (n = 1225), taxanes (n = 1173), lapatinib (n = 496), and capecitabine (n = 496). On univariable and adjusted analysis, patient-reported physical well-being, functional well-being, and BC subscale were all identified to be associated with OS, PFS, and grade ≥3 adverse events (P < 0.05). Patient-reported physical well-being was the most prognostic PRO for all assessed outcomes. The OS prognostic performance of physical well-being (c = 0.58) was superior to ECOG PS (c = 0.56) (P < 0.05), with multivariable analysis indicating that both provide independent information (P < 0.0001). CONCLUSIONS: PROs were identified as independent prognostic factors for OS, PFS, and grade ≥3 adverse events in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced BC initiating contemporary treatment options. Further, patient-reported physical well-being was more prognostic of OS than ECOG PS and contained independent information. PROs have value as prognostic and stratification factors for clinical use and research trials of anticancer treatment in HER2-positive ABC.

Drug-induced toxicity and patient reported outcomes in rheumatoid arthritis patients following intensive treated-to-target strategy: does ceasing therapy due to toxicity worsen outcomes in long term?

AIM: While the introduction of the treat-to-target (T2T) strategy has been an important advance in the management of rheumatoid arthritis (RA), the potential for increased toxicity due to use of concurrent drugs could adversely affect patient reported outcomes (PROs). The objective was to determine whether the cessation of therapy due to toxicity affects long-term improvement in PROs in patients treated according to T2T strategy. METHODS: A total of 149 patients from an inception cohort of early RA were included. The occurrence and severity of toxicity were monitored at each visit over 3 years. PROs studied were function (measured using health assessment questionnaire); pain, fatigue and patient global assessment (PtGA) all assessed using a 100 mm visual analogue scale; helplessness and health-related quality of life (HRQoL). For each PRO, effect of drug withdrawal was measured by comparing mean change in PROs among patients with no/temporary vs. permanent withdrawal. In addition, effects of frequency of drug withdrawals, weeks to withdrawal and number of drugs withdrawn were analysed using linear regression. RESULT: After 3 years, 56 (37.4%) patients ceased at least one drug permanently due to toxicity. Patients with no/temporary withdrawal (n = 93) achieved significantly greater improvement in function (mean change = -0.54 vs. -0.31, p = 0.033), pain (mean change = -39.82 vs. -5.02, p = 0.018), fatigue (mean change = -29.14 vs. -14.76, p = 0.015) and PtGA (mean change = -29.64 vs. -17.00, p = 0.018) compared with their counterparts. Higher frequency of withdrawals was associated with lesser improvements in function, pain, fatigue and PtGA, while the number of drugs withdrawn and the weeks to withdrawal had lesser effects. However, the cessation of the drugs due to their toxicity did not have a significant association with HRQoL and helplessness. CONCLUSION: Improvements in function, pain, fatigue and PtGA at 3 years were diminished for patients who ceased drugs due to toxicity while broader measures of HRQoL were not affected.

Meta-analysis of BRAF mutation as a predictive biomarker of benefit from anti-EGFR monoclonal antibody therapy for RAS wild-type metastatic colorectal cancer.

BACKGROUND: Metastatic colorectal cancer (mCRC) that harbours a BRAF V600E mutation (BRAF MT) is associated with poorer outcomes. However, whether this mutation is predictive of treatment benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) is uncertain. METHODS: We conducted a systematic review and meta-analysis of randomised controlled trials (RCTs) published up to July 2014 that evaluated the effect of BRAF MT on the treatment benefit from anti-EGFR mAbs for mCRC. RESULTS: Seven RCTs met the inclusion criteria for assessment of overall survival (OS), whereas eight RCTs met the inclusion criteria for assessment of progression-free survival (PFS). For RAS WT/BRAF MT tumours, the hazard ratio for OS benefit with anti-EGFR mAbs was 0.97 (95% CI; 0.67-1.41), whereas the hazard ratio was 0.81 (95% CI; 0.70-0.95) for RAS WT/BRAF WT tumours. However, the test of interaction (P=0.43) was not statistically significant, highlighting that the observed differences in the effect of anti-EGFR mAbs on OS according to the BRAF mutation status may be due to chance alone. Regarding PFS benefit with anti-EGFR mAbs, the hazard ratio was 0.86 (95% CI; 0.61-1.21) for RAS WT/BRAF MT tumours as compared with 0.62 (95% CI; 0.50-0.77) for RAS WT/BRAF WT tumours (test of interaction, P=0.07). INTERPRETATION: This meta-analysis demonstrates that there is insufficient evidence to definitively state that RAS WT/BRAF MT individuals attain a different treatment benefit from anti-EGFR mAbs for mCRC compared with RAS WT/BRAF WT individuals. As such, there are insufficient data to justify the exclusion of anti-EGFR mAb therapy for patients with RAS WT/BRAF MT mCRC.

Extended RAS mutations and anti-EGFR monoclonal antibody survival benefit in metastatic colorectal cancer: a meta-analysis of randomized, controlled trials.

BACKGROUND: Monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR) prolong survival in metastatic colorectal cancer (mCRC) Kirsten rat sarcoma viral oncogene (KRAS) exon 2 wild-type tumors. Recent evidence has suggested that other RAS mutations (in exons 3 and 4 of KRAS and exons 2, 3 and 4 of a related gene, NRAS) may also be predictive of resistance. METHODS: Systematic review and meta-analysis of randomized, controlled trials (RCTs) evaluating anti-EGFR mAbs that have assessed tumors for new RAS mutations. Tumors with the new RAS mutations were compared with both tumors without any RAS mutations and tumors with KRAS exon 2 mutations with respect to anti-EGFR treatment progression-free survival (PFS) and overall survival (OS) benefit. RESULTS: Nine RCTs comprising a total of 5948 participants evaluated for both KRAS exon 2 and new RAS mutations met the inclusion criteria. Approximately 20% of KRAS exon 2 wild-type tumors harbored one of the new RAS mutations. Tumors without any RAS mutations (either KRAS exon 2 or new RAS mutations) were found to have significantly superior anti-EGFR mAb PFS (P < 0.001) and OS (P = 0.008) treatment effect compared with tumors with any of the new RAS mutations. No difference in PFS or OS benefit was evident between tumors with KRAS exon 2 mutations and tumors with the new RAS mutations. Results were consistent between different anti-EGFR agents, lines of therapy and chemotherapy partners. Anti-EGFR mAb therapy significantly improved both PFS {hazard ratio 0.62 [95% confidence interval (CI) 0.50-0.76]} and OS [hazard ratio 0.87 (95% CI 0.77-0.99)] for tumors without any RAS mutations. No PFS or OS benefit was evident with use of anti-EGFR mAbs for tumors harboring any RAS mutation (P > 0.05). CONCLUSION: Tumors harboring one of the new RAS mutations are unlikely to significantly benefit from anti-EGFR mAb therapy in mCRC.

The effect of the UGT1A1*28 allele on survival after irinotecan-based chemotherapy: a collaborative meta-analysis.

To date, studies of irinotecan pharmacogenetics have mostly focused on the effect of the UGT1A1*28 allele on irinotecan-related toxicity. However, the clinical utility of routine UGT1A1*28 genotyping to pre-emptively adjust irinotecan dosage is dependent upon whether UGT1A1*28 also affects patient survival following irinotecan therapy. Previous observational studies evaluating the influence of UGT1A1*28 on survival have shown contradictory results. A systematic review and meta-analysis of both published and unpublished data were performed to summarize the available evidence of the relationship between the UGT1A1*28 allele and patient survival related to irinotecan therapy. Overall and progression-free survival meta-analysis data were available for 1524 patients and 1494 patients, respectively. The difference in the survival between patients of different UGT1A1*28 genotypes (homozygous, heterozygous or wild-type) who had received irinotecan was not found to be statistically significant. There was also no evidence of irinotecan dose, regimen or line of therapy having an impact on this association.

Pharmacogenomics of NAT2 and ABCG2 influence the toxicity and efficacy of sulphasalazine containing DMARD regimens in early rheumatoid arthritis.

Sulphasalazine (SSA) is a disease modifying anti-rheumatic drug (DMARD) that is commonly used to treat rheumatoid arthritis (RA). Plasma levels of SSA and its metabolite sulphapyridine are influenced by common polymorphisms in genes that encode N-acetyl transferase 2 (NAT2) and ATP-binding cassette protein G2 (ABCG2). Study participants had early RA that was treated with a combination DMARD regimen that included SSA. Toxicity was defined by cessation of SSA due to adverse effects and response as remission after 12 months of treatment. The effect of variables on toxicity was assessed by a Cox-proportional Hazard model and response by logistic regression. After correction for conventional variables, toxicity in 229 participants was influenced by NAT2 phenotype (hazard ratio=1.74 (95% confidence interval (CI) 1.01-3.21), P=0.044) and remission in 141 participants was associated with ABCG2 genotype (odds ratio=3.34 (95% CI 1.18-9.50), P=0.024). In our sample of early RA patients who were primarily treated with a combination of DMARDs, common variants in genes that encode NAT2 and ABCG2 were associated respectively with toxicity and response to SSA.

Exploration of the perceptions, barriers and drivers of pharmacogenomics practice among hospital pharmacists in Adelaide, South Australia.

There is little literature regarding the barriers to the uptake of pharmacogenomics (PG) in pharmacy practice, especially with respect to Australia. To date, pharmacists have seldom been engaged in discussions of these issues. This study aimed to obtain an in-depth understanding of these barriers by interviewing pharmacists in Adelaide, South Australia. Ethics approved semistructured interviews were carried out with 21 public hospital pharmacists. Analysis of the data identified themes including: confidence to engage in PG, clinician acceptance of a pharmacist PG role, and the importance of timely and relevant PG education. Interviewees thought that pharmacists could have a greater participation in PG in the future, but they questioned whether this would be possible at the moment given, among other factors, existing time and work constraints.

Interpreting the clinical utility of a pharmacogenomic marker based on observational association studies.

It is increasingly recognized that the clinical utility of a pharmacogenomic marker is a fundamental characteristic influencing the likelihood of successful clinical translation. Although appropriately designed and executed randomized controlled trials generally provide the most valid evidence for the clinical utility of a pharmacogenomic marker, such evidence may not always be available. Observational pharmacogenomic association studies are a common form of evidence available, but the assessment of clinical utility based on such evidence is often not straightforward. This paper aims to provide insight into this issue using a range of illustrative examples.

Challenges and limitations in the interpretation of systematic reviews: making sense of clopidogrel and CYP2C19 pharmacogenetics.

From 2010 to 2012, nine systematic reviews reported highly variable conclusions regarding the association between carriage of a cytochrome P450 2C19 loss-of-function allele and the risk of adverse cardiovascular (CV) events in individuals using clopidogrel. Possible contributors to the variable findings include differences in patient populations, CV end points, and statistical models utilized by the systematic reviews, as well as unexplained heterogeneity, inconsistent/incomplete reporting, and risk of publication bias with respect to the primary studies.

The importance of high-quality evidence of the long-term impact of nonfatal events used in randomized controlled trials: a case study of prasugrel.

Randomized controlled trials (RCTs) are the centerpiece of evidence-based medicine. However, because of the limited follow-up, additional evidence on the long-term consequences of the outcomes used in trials is commonly required for clinical and policy decision making. This article provides insights into the importance and challenges of using such evidence through the case study of nonfatal myocardial infarction (MI) and nonfatal bleeding with prasugrel.

Prasugrel vs. clopidogrel for cytochrome P450 2C19-genotyped subgroups: integration of the TRITON-TIMI 38 trial data.

BACKGROUND: Prasugrel is a newly marketed antiplatelet drug with improved cardiac outcomes as compared with clopidogrel for acute coronary syndromes involving percutaneous coronary intervention (PCI). Analysis of a subset of the TRITON-TIMI 38 trial demonstrated that cytochrome P450 2C19 (CYP2C19) reduced-function genotypes are associated with differential clinical responses to clopidogrel, but not prasugrel. Whether the CYP2C19 genotype has the potential to influence clinical choice of these drugs prior to PCI for individuals with unstable angina or non-ST segment elevation myocardial infarction is currently uncertain. METHODS AND RESULTS: An exploratory, secondary analysis was undertaken to estimate the clinical benefit of prasugrel over clopidogrel in subgroups defined by CYP2C19 genotype, by integrating the published results of the genetic substudy and the overall TRITON-TIMI 38 trial. Individuals with a CYP2C19 reduced-metabolizer genotype were estimated to have a substantial reduction in the risk of the composite primary outcome (cardiovascular death, myocardial infarction, or stroke) with prasugrel as compared with clopidogrel [relative risk (RR) 0.57; 95% confidence interval (CI) 0.39-0.83]. For CYP2C19 extensive metabolizers (∼70% of the population), however, the composite outcome risks with prasugrel and clopidogrel were not substantially different (RR 0.98; 95% CI 0.80-1.20). CONCLUSIONS: Integration of the TRITON-TIMI 38 data suggests that the CYP2C19 genotype can discriminate between individuals who receive extensive benefit from using prasugrel instead of clopidogrel, and individuals with comparable clinical outcomes with prasugrel and clopidorel. Thus, CYP2C19 genotyping has the potential to guide the choice of antiplatelet therapy, and further research is warranted to validate this estimate.

Towards integrated ADME prediction: past, present and future directions for modelling metabolism by UDP-glucuronosyltransferases.

Undesirable absorption, distribution, metabolism, excretion (ADME) properties are the cause of many drug development failures and this has led to the need to identify such problems earlier in the development process. This review highlights computational (in silico) approaches that have been used to identify the characteristics of ligands influencing molecular recognition and/or metabolism by the drug-metabolising enzyme UDP-gucuronosyltransferase (UGT). Current studies applying pharmacophore elucidation, 2D-quantitative structure metabolism relationships (2D-QSMR), 3D-quantitative structure metabolism relationships (3D-QSMR), and non-linear pattern recognition techniques such as artificial neural networks and support vector machines for modelling metabolism by UGT are reported. An assessment of the utility of in silico approaches for the qualitative and quantitative prediction of drug glucuronidation parameters highlights the benefit of using multiple pharmacophores and also non-linear techniques for classification. Some of the challenges facing the development of generalisable models for predicting metabolism by UGT, including the need for screening of more diverse structures, are also outlined.

In silico insights: chemical and structural characteristics associated with uridine diphosphate-glucuronosyltransferase substrate selectivity.

1. Undesirable absorption, distribution, metabolism, excretion properties are the cause of many drug development failures and this has led to the need to identify such problems earlier in the development process. This work highlights computational (in silico) approaches used to identify characteristics influencing the metabolism of uridine diphosphate (UDP)-glucuronosyltransferase (UGT) substrates. Uridine diphosphate-glucuronosyltransferase facilitates conjugation between glucuronic acid and a nucleophilic site within a substrate and is one of the major drug-metabolizing enzymes. 2. An understanding of the relevant structural and chemical characteristics of the ligand and the enzyme active site will lead to greater utilization of metabolically relevant structural information in drug design. However, an X-ray crystal structure of UGT is not yet available, little has been reported about important structurally or catalytically relevant amino acids and only recently has the reported substrate profile of UGT isoforms reached an interpretable level. 3. A database of all the known substrates and non-substrates for each human UGT isoform was assembled and a range of modelling approaches assessed. Currently, pharmacophore models developed using Catalyst (Accelrys, San Diego, CA, USA) indicate that substrates of the UGT1A family share two key hydrophobic regions 3 and 6-7 A from the site of glucuronidation in a well-defined spatial geometry. Furthermore, two-dimensional quantitative structure-activity relationship models show significant reliance on substrate lipophilicity and a range of other descriptors that are known to capture information relevant to ligand-protein interactions. 4. In conclusion, substrate-based modelling of UGT appears both useful and feasible, with significant potential for determining aspects of chemical structure associated with metabolism and to quantify the nature of the relationship for UGT substrates. The development of a novel, user-defined 'glucuronidation feature' for alignment was crucial to the development of pharmacophore-based UGT models.