on behalf of the PLATO Investigators Background-In the Platelet Inhibition and Patient Outcomes (PLATO) trial, a prespecified subgroup analysis showed a significant interaction between treatment and region (Pϭ0.045), with less effect of ticagrelor in North America than in the rest of the world. Methods and Results-Reasons for the interaction were explored independently by 2 statistical groups. Systematic errors in trial conduct were investigated. Statistical approaches evaluated the likelihood of play of chance. Cox regression analyses were performed to quantify how much of the regional interaction could be explained by patient characteristics and concomitant treatments, including aspirin maintenance therapy. Landmark Cox regressions at 8 time points evaluated the association of selected factors, including aspirin dose, with outcomes by treatment. Systematic errors in trial conduct were ruled out. Given the large number of subgroup analyses performed and that a result numerically favoring clopidogrel in at least 1 of the 4 prespecified regions could occur with 32% probability, chance alone cannot be ruled out. More patients in the United States (53.6%) than in the rest of the world (1.7%) took a median aspirin dose Ն300 mg/d. Of 37 baseline and postrandomization factors explored, only aspirin dose explained a substantial fraction of the regional interaction. In adjusted analyses, both Cox regression with median maintenance dose and landmark techniques showed that, in patients taking low-dose maintenance aspirin, ticagrelor was associated with better outcomes compared with clopidogrel, with statistical superiority in the rest of the world and similar outcomes in the US cohort. Conclusions-The regional interaction could arise from chance alone. Results of 2 independently performed analyses identified an underlying statistical interaction with aspirin maintenance dose as a possible explanation for the regional difference. The lowest risk of cardiovascular death, myocardial infarction, or stroke with ticagrelor compared with clopidogrel is associated with a low maintenance dose of concomitant aspirin. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00391872. (Circulation. 2011;124:544-554.)

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IgA nephropathy (IgAN) is an important cause of ESKD for which there are no approved therapies. A challenge for evaluating treatments for IgAN is the usual long time course for progression to ESKD. The aim of this Kidney Health Initiative project was to identify surrogate end points that could serve as reliable predictors of a treatment's effect on long-term kidney outcomes in IgAN and be used as a basis for approval. Proteinuria was identified as the most widely recognized and well studied risk factor for progression to ESKD in IgAN. The workgroup performed a critical review of the data on proteinuria reduction as a surrogate end point for a treatment's effect on progression to ESKD in IgAN. Epidemiologic data indicate a strong and consistent relationship between the level and duration of proteinuria and loss of kidney function. Trial-level analyses of data from 13 controlled trials also show an association between treatment effects on percent reduction of proteinuria and treatment effects on a composite of time to doubling of serum creatinine, ESKD, or death. We conclude that data support the use of proteinuria reduction as a reasonably likely surrogate end point for a treatment's effect on progression to ESKD in IgAN. In the United States, reasonably likely surrogate end points can be used as a basis for accelerated approval of therapies intended to treat serious or life-threatening conditions, such as IgAN. The clinical benefit of products approved under this program would need to be verified in a postmarketing confirmatory trial.

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It is a common misconception that high correlation between biomarkers and true end point justify the use of the former as surrogates. To statistically validate surrogate end points, a high correlation between the treatment effects on the surrogate and true end point needs to be established across groups of patients treated with two alternative interventions. The levels of association observed in this study indicate that the effect of hormonal treatment on OS cannot be predicted with a high degree of precision from observed treatment effects on PSA end points, and thus statistical validity is unproven. In practice, non-null treatment effects on OS can be predicted only from precisely estimated large effects on time to PSA progression (TTPP; hazard ratio, < 0.50).

Background:Immune Modulation and Gemcitabine Evaluation-1, a randomised, open-label, phase II, first-line, proof of concept study (NCT01303172), explored safety and tolerability of IMM-101 (heat-killed Mycobacterium obuense; NCTC 13365) with gemcitabine (GEM) in advanced pancreatic ductal adenocarcinoma.Methods:Patients were randomised (2 : 1) to IMM-101 (10 mg ml−l intradermally)+GEM (1000 mg m−2 intravenously; n=75), or GEM alone (n=35). Safety was assessed on frequency and incidence of adverse events (AEs). Overall survival (OS), progression-free survival (PFS) and overall response rate (ORR) were collected.Results:IMM-101 was well tolerated with a similar rate of AE and serious adverse event reporting in both groups after allowance for exposure. Median OS in the intent-to-treat population was 6.7 months for IMM-101+GEM v 5.6 months for GEM; while not significant, the hazard ratio (HR) numerically favoured IMM-101+GEM (HR, 0.68 (95% CI, 0.44–1.04, P=0.074). In a pre-defined metastatic subgroup (84%), OS was significantly improved from 4.4 to 7.0 months in favour of IMM-101+GEM (HR, 0.54, 95% CI 0.33–0.87, P=0.01).Conclusions:IMM-101 with GEM was as safe and well tolerated as GEM alone, and there was a suggestion of a beneficial effect on survival in patients with metastatic disease. This warrants further evaluation in an adequately powered confirmatory study.