Sumati Rao

Clinical and economic burden of extra-articular manifestations in ankylosing spondylitis patients treated with anti-tumor necrosis factor agents

Abstract Objective: To assess concomitant extra-articular manifestation (EAM) rates in patients with ankylosing spondylitis (AS) treated with anti-tumor necrosis factor (anti-TNF) agents and examine the economic burden of uveitis and inflammatory bowel disease (IBD) in French and German AS patients. Methods: Previous analyses of uveitis and IBD in AS patients treated with infliximab, etanercept or adalimumab were identified in PubMed/Medline (January 2000 to August 2011). A supplemental analysis incorporated more recent adalimumab clinical trial data (ATLAS [NCT00085644] and RHAPSODY [NCT00478660]). For resource utilization/costs associated with EAMs, the search was expanded to general spondyloarthritis (SpA) conditions (i.e., AS, reactive or psoriatic arthritis, psoriatic spondylitis, IBD and undifferentiated SpA). Direct and indirect yearly costs associated with AS-associated uveitis and IBD were estimated based on interviews with French and German clinicians and literature review. Results: The pooled average rate of anterior uveitis (AU) flares for patients treated with anti-TNF therapy in two meta-analyses and supplemental adalimumab clinical trials was 4.9/100-patient-years (PYs). AU rates (per 100-PYs) were 3.4, 3.7 and 5.7 for infliximab (p = 0.26 vs etanercept; p = 0.86 vs adalimumab), adalimumab (p = 0.033 vs etanercept) and etanercept, respectively. IBD flares (per 100-PYs) were 0.2 for infliximab (p < 0.001 vs etanercept; p = 0.18 vs adalimumab), 0.63 for adalimumab (p = 0.009 vs etanercept) and 2.2 for etanercept. No studies assessing EAM-associated resource utilization or costs in AS patients were found. Direct medical costs associated with IBD treatment ranged from €483 (Germany) to €6443 (France). Clinician-estimated AS-related uveitis direct medical costs were €1410 (Germany) and €1812 (France). Conclusions: Clinical data synthesis demonstrated significantly lower AU flare rates with adalimumab vs etanercept and significantly lower IBD rates with both adalimumab and infliximab vs etanercept. Economic analysis indicated substantial costs associated with AU and IBD flares secondary to AS in France and Germany. Future economic evaluations of anti-TNF agents should incorporate EAMs and subsequent treatment costs. Limitations include restricted availability of randomized, placebo-controlled clinical trial data, inclusion of data from open-label studies, lack of real-world (i.e., non-trial-based) EAM rates and a lack of EAM-specific direct and indirect costs with which to compare the results presented herein.

Matching-adjusted indirect comparison of adalimumab vs etanercept and infliximab for the treatment of psoriatic arthritis

Abstract Objectives: No head-to-head trial has compared the efficacy of adalimumab vs etanercept and infliximab for psoriatic arthritis (PsA). This study implements a matching-adjusted indirect comparison technique to address that gap. Methods: Patient-level data from a placebo-controlled trial of adalimumab (ADEPT) were re-weighted to match average baseline characteristics from pivotal published trials of etanercept and infliximab. ADEPT patients were re-weighted by odds of enrollment in comparator trials, estimated using logistic regression. Matched-on characteristics included PsA duration, age, gender, severity, active psoriasis, and concomitant treatment. After matching, placebo-adjusted treatment arms were compared at weeks 12 (or 14) and 24. Outcomes included ACR20/50/70, PsARC, HAQ, and modified TSS. PASI50/75/90 were compared for patients with active psoriasis. Cost per responder (CPR) was assessed in the US and Germany using matching-adjusted end-points and drug list prices. Statistical significance was assessed using weighted t-tests. Results: After matching, adalimumab-treated patients had greater placebo-adjusted rates of ACR70 and PASI50/75/90 at week 24 compared with etanercept (all p < 0.05). Adalimumab patients had a higher placebo-adjusted rate of ACR70 than infliximab at week 14 (p = 0.034). Adalimumab treatment had lower CPR for ACR70 and PASI50/75/90 compared with etanercept at week 24, in both the US and Germany (all p < 0.02). Adalimumab had lower CPR than infliximab for all outcomes at week 24 (all p < 0.05). Conclusion: Adalimumab is associated with higher ACR70 and PASI50/75/90 response rates than etanercept at week 24 and a higher ACR70 response rate than infliximab at week 14. Adalimumab has significant advantages over etanercept and infliximab in CPR across multiple end-points. Key limitations: The matching-adjusted indirect comparison method cannot account for unobserved differences in patient characteristics across trials, and only a head-to-head randomized clinical trial can fully avoid the limitations of indirect comparisons. CPR findings are limited to the US and German markets, and may not be generalizable to other markets with different relative pricing.

Application of dynamic modeling for survival estimation in advanced renal cell carcinoma

Objective In oncology, extrapolation of clinical outcomes beyond trial duration is traditionally achieved by parametric survival analysis using population-level outcomes. This approach may not fully capture the benefit/risk profile of immunotherapies due to their unique mechanisms of action. We evaluated an alternative approach—dynamic modeling—to predict outcomes in patients with advanced renal cell carcinoma. We compared standard parametric fitting and dynamic modeling for survival estimation of nivolumab and everolimus using data from the phase III CheckMate 025 study. Methods We developed two statistical approaches to predict longer-term outcomes (progression, treatment discontinuation, and survival) for nivolumab and everolimus, then compared these predictions against follow-up clinical trial data to assess their proximity to observed outcomes. For the parametric survival analyses, we selected a probability distribution based on its fit to observed population-level outcomes at 14-month minimum follow-up and used it to predict longer-term outcomes. For dynamic modeling, we used a multivariate Cox regression based on patient-level data, which included risk scores, and probability and duration of response as predictors of longer-term outcomes. Both sets of predictions were compared against trial data with 26- and 38-month minimum follow-up. Results Both statistical approaches led to comparable fits to observed trial data for median progression, discontinuation, and survival. However, beyond the trial duration, mean survival predictions differed substantially between methods for nivolumab (30.8 and 51.5 months), but not everolimus (27.2 and 29.8 months). Longer-term follow-up data from CheckMate 025 and phase I/II studies resembled dynamic model predictions for nivolumab. Conclusions Dynamic modeling can be a good alternative to parametric survival fitting for immunotherapies because it may help better capture the longer-term benefit/risk profile and support health-economic evaluations of immunotherapies.