Quantitative systems pharmacology analysis of drug combination and scaling to humans: the interaction between noradrenaline and vasopressin in vasoconstriction.

BACKGROUND AND PURPOSE: Development of combination therapies has received significant interest in recent years. Previously, a two-receptor one-transducer (2R-1T) model was proposed to characterize drug interactions with two receptors that lead to the same phenotypic response through a common transducer pathway. We applied, for the first time, the 2R-1T model to characterize the interaction of noradrenaline and arginine-vasopressin on vasoconstriction and performed inter-species scaling to humans using this mechanism-based model. EXPERIMENTAL APPROACH: Contractile data were obtained from in vitro rat small mesenteric arteries after exposure to single or combined challenges of noradrenaline and arginine-vasopressin with or without pretreatment with the irreversible α-adrenoceptor antagonist, phenoxybenzamine. Data were analysed using the 2R-1T model to characterize the observed exposure-response relationships and drug-drug interaction. The model was then scaled to humans by accounting for differences in receptor density. KEY RESULTS: With receptor affinities set to published values, the 2R-1T model satisfactorily characterized the interaction between noradrenaline and arginine-vasopressin in rat small mesenteric arteries (relative standard error ≤20%), as well as the effect of phenoxybenzamine. Furthermore, after scaling the model to human vascular tissue, the model also adequately predicted the interaction between both agents on human renal arteries. CONCLUSIONS AND IMPLICATIONS: The 2R-1T model can be of relevance to quantitatively characterize the interaction between two drugs that interact via different receptors and a common transducer pathway. Its mechanistic properties are valuable for scaling the model across species. This approach is therefore of significant value to rationally optimize novel combination treatments.

Abatacept or infliximab for patients with rheumatoid arthritis and inadequate response to methotrexate: an Italian trial-based and real-life cost-consequence analysis.

OBJECTIVES: In the 1-year, double-blind, placebo-controlled ATTEST trial, efficacy of abatacept or infliximab versus placebo was reported in patients with rheumatoid arthritis (RA) and an inadequate response to methotrexate (MTX). The current study estimated trial-based and real-life costs of abatacept and infliximab for achieving pre-defined remission or low disease activity state (LDAS). METHODS: Quantity of drug, serious adverse event (SAE) rates and time (months) in remission or LDAS were taken from ATTEST for the trial-based calculation to derive a cost per remitting/LDAS patient and a cost per patient-month in remission/LDAS. Trial-based and real-life scenarios were performed. RESULTS: The annual trial-based costs per remitting/LDAS patient were €70.238/€37.208 for abatacept and €85.565/€46.602 for infliximab. In the first 6 months of the ATTEST trial, costs per patient-month in remission/LDAS were higher for abatacept (€11.024 and €6.018, respectively), relative to infliximab (€8.347 and €4.174, respectively). Over the full 12-month trial period cost per month in remission/LDAS estimates were only slightly in favour of infliximab (€6.959/€3.625) relative to abatacept (€7.297/€3.909). Assuming extension of treatment under real life conditions the cost per month in remission/LDAS turned substantially in favour of abatacept (€5.321/€2.819), as compared to infliximab (€7.189/€3.916). The higher initiation cost for abatacept to achieve remission/LDAS would be offset after a total 14.6 and 16.1 months of treatment, respectively, if treatment extended beyond 6 months under real-life conditions. These results proved to be robust when it was assumed that the (i) sharing of vials across patients completely averted infliximab wastage, (ii) AE risks were similar and (iii) onset of response was slower for abatacept. CONCLUSIONS: Our findings suggest a lower cost-consequence for abatacept during real-life treatment.

Economic evaluation of posaconazole versus fluconazole prophylaxis in patients with graft-versus-host disease (GVHD) in the Netherlands.

The objective of this study was to evaluate the cost-effectiveness of posaconazole versus fluconazole for the prevention of invasive fungal infections (IFI) in graft-versus-host disease (GVHD) patients in the Netherlands. A decision analytic model was developed based on a double-blind randomized trial that compared posaconazole with fluconazole antifungal prophylaxis in recipients of allogeneic HSCT with GVHD who were receiving immunosuppressive therapy (Ullmann et al., N Engl J Med 356:335-347, 2007). Clinical events were modeled with chance nodes reflecting probabilities of IFIs, IFI-related death, and death from other causes. Data on life expectancy, quality-of-life, medical resource consumption, and costs were obtained from the literature. The total cost with posaconazole amounted to 9,428 (95% uncertainty interval 7,743-11,388), which is 4,566 (2,460-6,854) more than those with fluconazole. Posaconazole prophylaxis resulted in 0.17 (0.02-0.36) quality adjusted life year (QALY) gained compared to fluconazole prophylaxis, corresponding to an incremental cost effectiveness ratio (ICER) of 26,225 per QALY gained. A scenario analysis demonstrated that at an increased background IFI risk (from 9% to 15%) the ICER was 13,462 per QALY. Given the underlying data and assumptions, posaconazole prophylaxis is expected to be cost-effective relative to fluconazole in recipients of allogeneic HSCT developing GVHD in the Netherlands. The cost-effectiveness of posaconazole depends on the IFI risk, which can vary by hospital.

Cost effectiveness of etoricoxib versus celecoxib and non-selective NSAIDS in the treatment of ankylosing spondylitis.

To evaluate the cost effectiveness of etoricoxib (90 mg/day) relative to celecoxib (200 or 400 mg/day), and the non-selective NSAIDs naproxen (1000 mg/day) and diclofenac (150 mg/day) in the initial treatment of ankylosing spondylitis (AS) from the UK NHS perspective. A Bayesian cost-effectiveness model was developed to estimate the costs and benefits associated with initiating AS treatment with etoricoxib, celecoxib, diclofenac or naproxen. Efficacy, safety and medical resource and cost data were obtained from the literature. The obtained efficacy estimates were synthesized with a mixed treatment comparison meta-analysis. Treatment benefit and degree of disease activity, as reflected with Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores, were related to QALYs and AS-specific costs (related to BASDAI). Other cost outcomes related to drug acquisition, and gastrointestinal and cardiovascular safety. Uncertainty in the source data was translated into uncertainty in cost-effectiveness estimates and therefore decision uncertainty. Costs and outcomes were discounted at 3.5% per annum. There was a >98% probability that treatment with etoricoxib results in greater QALYs than the other interventions. Over a 30-year time horizon, starting AS treatment with etoricoxib was associated with about 0.4 more QALYs than the other interventions. At 2 years there was a 77% probability that etoricoxib had the lowest cost. This increased to >99% at 30 years. Etoricoxib is expected to save 13 620 UK pounds (year 2007 values) relative to celecoxib (200/400 mg), 9957 UK pounds relative to diclofenac and 9863 UK pounds relative to naproxen. For a willingness-to-pay ceiling ratio of 20 000 UK pounds per QALY, there was a >97% probability that etoricoxib was the most cost-effective treatment. Additional analysis with different assumptions, including celecoxib 200 mg, and ignoring cost-offsets associated with improvements in disease activity, supported these findings. This economic evaluation suggests that, from the UK NHS perspective, etoricoxib is the most cost-effective initial NSAID treatment for AS patients.

Efficacy of intranasal fentanyl spray versus other opioids for breakthrough pain in cancer.

OBJECTIVE: To compare the efficacy of intranasal fentanyl spray (INFS), oral transmucosal fentanyl citrate (OTFC), fentanyl buccal tablet (FBT) and oral morphine (OM) for the treatment of breakthrough cancer pain (BTCP). METHODS: A systematic literature review (Medline, EMBASE, BIOSIS; 1996-2007) identified six randomised controlled trials (RCTs) investigating the effects of INFS, OTFC, FBT and OM for the treatment of BTCP. The endpoint of interest was pain intensity difference (PID, reported on a 0-10 numeric rating scale [NRS]) up to 60 minutes after intake. Results of all trials were analysed simultaneously with a mixed treatment comparison (extended meta-analysis). MTC can be considered a valid method when included studies are comparable regarding effect modifying baseline patient and study characteristics. RESULTS: INFS provided the greatest reduction in pain relative to placebo: PID 1.7 points (95% CrI: 1.4; 1.9) at 15 minutes, 2.0 (1.6; 2.3) at 30 minutes, 2.0 (1.5; 2.4) at 45 minutes and 1.9 (1.5; 2.4) at 60 minutes. PID for OTFC and FBT relative to placebo were 0.4 (0.0; 0.8) and 0.5 (0.3; 0.7) at 15 minutes. Both treatments provided a reduction in pain superior to placebo at other time points. INFS displayed a more than 99% probability of providing the greatest pain reduction out of all interventions compared at 15 minutes after intake. This was maintained for any measured time point before 45 minutes when compared to FBT and for any measured time point before 60 minutes when compared to OTFC. Only from 45 minutes onwards did OM show a greater pain reduction than placebo. CONCLUSION: Based on currently available evidence, INFS is expected to provide the greatest improvement in the treatment of BTCP. Due to its slow onset to effect OM cannot be considered an efficacious treatment for BTCP.

Effects of dietary supplementation with conjugated linoleic acid on experimental human rhinovirus infection and illness.

BACKGROUND: Because studies suggest that the dietary supplement conjugated linoleic acid (CLA) has immunomodulatory activities that might benefit common colds, we performed two studies of CLA effects in experimental human rhinovirus (HRV) infection. METHODS: The first study explored whether CLA supplementation (Safflorin; Loders Croklaan, BV, Wormerveer, the Netherlands) altered the virological or clinical course of experimental HRV infection, and the second explored whether CLA affected the frequency and severity of HRV cold-associated sore throat and cough. The trials were randomized, double-blinded and placebo-controlled. In total, 50 healthy volunteers aged 18-45 years and susceptible to HRV type-39 (serum neutralizing antibody titre < or = 1:2) participated in study 1 and 80 similar volunteers susceptible to Hank's HRV participated in study 2. Participants ingested CLA 2 g/day or placebo for 4 weeks before and 4 days following intranasal HRV inoculation. The primary endpoint for study 1 was the frequency of colds and for study 2 was the symptom severity scores for sore throat and cough. RESULTS: In study 1, 10/24 (42%) placebo compared with 7/21 (33%) CLA participants developed colds (P = 0.53). CLA was associated with significant reductions in mean scores for cough (0 CLA versus 0.9 placebo) and sore throat (0.8 CLA versus 2.9 placebo). In study 2, clinical colds developed in 19/33 (58%) placebo and 27/43 (63%) CLA participants. Symptom scores for cough (0.9 CLA versus 1.0 placebo) and sore throat (2.6 CLA versus 3.2 placebo) were not significantly different. Similarly no differences in nasal viral titres or serological responses were found. CONCLUSIONS: CLA dietary supplementation had no consistent effects on the virological or clinical course of experimental HRV colds. A larger study would be required to detect more subtle effects of CLA on HRV cold-associated symptoms.

Economic evaluation of posaconazole vs. standard azole prophylaxis in high risk neutropenic patients in the Netherlands.

BACKGROUND: Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients experience prolonged neutropenia after treatment with intensive chemotherapy, leading to a high risk of invasive fungal infections (IFI). The present study evaluates the cost effectiveness of posaconazole vs. standard azoles for the prevention of IFIs in neutropenic patients in the Netherlands. METHODS: A decision-tree model was developed using data from a randomized trial that compared posaconazole and standard azole (fluconazole or itraconazole) prophylaxis in neutropenic patients receiving remission-induction chemotherapy for AML/MDS (Cornely et al., N Engl J Med 2007;356:348-359). Following initiation of prophylaxis, clinical events are modeled with chance nodes reflecting probabilities of IFIs, IFI-related death, and death from other causes. Patients surviving the prophylaxis are assumed to have a life expectancy according to the underlying condition. This allows translation of the trial outcomes to a lifetime horizon. Data on life expectancy, quality of life, medical resource consumption and costs were obtained from the literature. Model outcomes include cost per life year (LY) gained and cost per quality adjusted life year (QALY) gained. RESULTS: The total cost (treatment of breakthrough IFI + prophylaxis) for posaconazole amounted to 4412 euros (95% uncertainty interval 3403 euros - 5666 euros), which is -183 euros (-1985 euros to 1564 euros) less than costs with standard azoles. Posaconazole prophylaxis resulted in 0.08 (0.02-0.15) QALYs gained in comparison with prophylaxis with standard azoles. Results from a probabilistic sensitivity analysis indicate that there is a 90% probability that the cost per QALY gained with posaconazole is below 20,000 euros. Additional scenario analyzes with different assumptions confirmed these findings. CONCLUSION: Given the underlying data and assumptions, the economic evaluation demonstrated that posaconazole prophylaxis is expected to be cost-effective compared with fluconazole/itraconazole in neutropenic AML/MDS patients after intensive chemotherapy.

Bayesian meta-analysis of multiple treatment comparisons: an introduction to mixed treatment comparisons.

Recently, mixed treatment comparisons (MTC) have been presented as an extension of traditional meta-analysis by including multiple different pairwise comparisons across a range of different interventions. MTC allow for indirect comparisons and can therefore provide very useful information for clinical and reimbursement decision-making in the absence of head-to-head data. In this article, we provide an introductory overview of MTC illustrated with example analyses of different drug treatments in rheumatoid arthritis using a continuous patient-reported end point. As a background, we start with an overview of the traditional meta-analyses for pairwise trials, and the difference between a traditional approach and a Bayesian approach. Next, the Bayesian MTC for continuous outcomes are presented. We finish with a discussion of how MTC can best be presented in order to maximize acceptance by target audiences, i.e., clinicians and market access decision-makers.

Economic evaluation of caspofungin versus liposomal amphotericin B for empiric antifungal treatment in patients with neutropenic fever in Italy.

OBJECTIVE: To evaluate the cost-effectiveness of caspofungin versus liposomal amphotericin B as empiric antifungal treatment in patients with neutropenic fever in Italy. METHODS: The cost-effectiveness of caspofungin versus liposomal amphotericin B was evaluated using a decision-tree model. Patients were stratified by presence or absence of baseline infection. Model outcomes included success in terms of resolution of fever, resolution of baseline infection, absence of breakthrough infection, survival, and quality-adjusted life years (QALYs) saved. Discontinuation because of nephrotoxicity or other adverse events were included in the model. Efficacy and safety data were based on a randomized, double-blind, multinational trial of caspofungin compared to liposomal amphotericin B (Walsh 2004). Information on life expectancy, quality of life, medical resource consumption, and costs was obtained from the literature. RESULTS: The caspofungin estimated total treatment cost amounted to 8351 euros (95% uncertainty interval 7801 euros-8903 euros), which is 3470 euros (2575 euros-4382 euros) less than with liposomal amphotericin B. Treatment with caspofungin resulted in 0.25 (-0.11; 0.59) QALYs saved in comparison to treatment with liposomal amphotericin B. Probabilistic sensitivity analysis demonstrated a 93% probability that caspofungin was economically dominant, i.e., cost and QALY saving, and a probability of more than 99% that the costs per QALY saved were below 20,000 euros, a commonly accepted threshold for cost-effectiveness. Additional analyses with alternative doses of liposomal amphotericin B confirmed these findings. CONCLUSION: Given the underlying assumptions, our economic evaluation demonstrated that caspofungin is cost-effective compared to liposomal amphotericin B in empiric antifungal treatment of patients with neutropenic fever in Italy.