Time-to-event estimands and loss to follow-up in oncology in light of the estimands guidance.

Time-to-event estimands are central to many oncology clinical trials. The estimands framework (addendum to the ICH E9 guideline) calls for precisely defining the treatment effect of interest to align with the clinical question of interest and requires predefining the handling of intercurrent events (ICEs) that occur after treatment initiation and "affect either the interpretation or the existence of the measurements associated with the clinical question of interest." We discuss a practical problem in clinical trial design and execution, that is, in some clinical contexts it is not feasible to systematically follow patients to an event of interest. Loss to follow-up in the presence of intercurrent events can affect the meaning and interpretation of the study results. We provide recommendations for trial design, stressing the need for close alignment of the clinical question of interest and study design, impact on data collection, and other practical implications. When patients cannot be systematically followed, compromise may be necessary to select the best available estimand that can be feasibly estimated under the circumstances. We discuss the use of sensitivity and supplementary analyses to examine assumptions of interest.

Duration of and time to response in oncology clinical trials from the perspective of the estimand framework.

Duration of response (DOR) and time to response (TTR) are typically evaluated as secondary endpoints in early-stage clinical studies in oncology when efficacy is assessed by the best overall response and presented as the overall response rate. Despite common use of DOR and TTR in particular in single-arm studies, the definition of these endpoints and the questions they are intended to answer remain unclear. Motivated by the estimand framework, we present relevant scientific questions of interest for DOR and TTR and propose corresponding estimand definitions. We elaborate on how to deal with relevant intercurrent events which should follow the same considerations as implemented for the primary response estimand. A case study in mantle cell lymphoma illustrates the implementation of relevant estimands of DOR and TTR. We close the paper with practical recommendations to implement DOR and TTR in clinical study protocols.

Quantification of follow-up time in oncology clinical trials with a time-to-event endpoint: Asking the right questions.

For the analysis of a time-to-event endpoint in a single-arm or randomized clinical trial it is generally perceived that interpretation of a given estimate of the survival function, or the comparison between two groups, hinges on some quantification of the amount of follow-up. Typically, a median of some loosely defined quantity is reported. However, whatever median is reported, is typically not answering the question(s) trialists actually have in terms of follow-up quantification. In this paper, inspired by the estimand framework, we formulate a comprehensive list of relevant scientific questions that trialists have when reporting time-to-event data. We illustrate how these questions should be answered, and that reference to an unclearly defined follow-up quantity is not needed at all. In drug development, key decisions are made based on randomized controlled trials, and we therefore also discuss relevant scientific questions not only when looking at a time-to-event endpoint in one group, but also for comparisons. We find that different thinking about some of the relevant scientific questions around follow-up is required depending on whether a proportional hazards assumption can be made or other patterns of survival functions are anticipated, for example, delayed separation, crossing survival functions, or the potential for cure. We conclude the paper with practical recommendations.

Estimands in hematologic oncology trials.

The estimand framework included in the addendum to the ICH E9 guideline facilitates discussions to ensure alignment between the key question of interest, the analysis, and interpretation. Therapeutic knowledge and drug mechanism play a crucial role in determining the strategy and defining the estimand for clinical trial designs. Clinical trials in patients with hematological malignancies often present unique challenges for trial design due to complexity of treatment options and existence of potential curative but highly risky procedures, for example, stem cell transplant or treatment sequence across different phases (induction, consolidation, maintenance). Here, we illustrate how to apply the estimand framework in hematological clinical trials and how the estimand framework can address potential difficulties in trial result interpretation. This paper is a result of a cross-industry collaboration to connect the International Conference on Harmonisation (ICH) E9 addendum concepts to applications. Three randomized phase 3 trials will be used to consider common challenges including intercurrent events in hematologic oncology trials to illustrate different scientific questions and the consequences of the estimand choice for trial design, data collection, analysis, and interpretation. Template language for describing estimand in both study protocols and statistical analysis plans is suggested for statisticians' reference.

Efficacy and safety of ciclesonide once daily and fluticasone propionate twice daily in children with asthma.

BACKGROUND: Ciclesonide is a new inhaled corticosteroid (ICS). Information about its clinical efficacy and safety in relation to other ICS in children is needed for clinical positioning. OBJECTIVE: This 12-week, randomized, double-blind, double-dummy, three-arm, parallel-group study compared the efficacy and safety of ciclesonide with fluticasone propionate in children with mainly moderate and severe persistent asthma. METHODS: Seven hundred and forty-four patients (aged 6-11 years) were randomized to ciclesonide (80 or 160 microg once daily) or fluticasone propionate (88 microg twice daily), following a 2-4-week run-in. Efficacy measurements included forced expiratory flow in 1s (FEV(1)), morning peak expiratory flow (PEF), asthma symptom scores, rescue medication use and quality of life. Systemic effect was assessed by 24-hour urine free cortisol adjusted for creatinine. RESULTS: FEV(1) and morning PEF increased from baseline in all groups (p<0.0001). Ciclesonide 160 microg was not inferior to fluticasone propionate 176 microg for FEV(1) (p=0.0030, one-sided). In all groups, asthma symptom score sums and rescue medication use significantly improved (p<0.0001). The percentages of asthma symptom-, rescue medication- and nocturnal awakening-free days were high, with no significant differences between treatments. Quality of life scores improved with all treatments (p<0.0001). A significant dose-response occurred between low and higher doses of ciclesonide for exacerbations and asthma control definitions. The incidences of adverse events were comparable across treatments. Urine free cortisol levels decreased significantly with fluticasone propionate (p=0.0103), but not with ciclesonide. CONCLUSION: Once-daily ciclesonide has a clinical effect similar to that of fluticasone propionate, but does not suppress cortisol excretion, in children with moderate and severe asthma.

Efficacy and safety of ciclesonide in patients with severe asthma: a 12-week, double-blind, randomized, parallel-group study with long-term (1-year) follow-up.

OBJECTIVE: To investigate the efficacy and safety of ciclesonide in patients with severe asthma over a 1-year period. RESEARCH DESIGN AND METHODS: Patients aged 18 - 75 years with persistent asthma were enrolled in a 12-week, double-blind, randomized study and treated with ciclesonide 320 or 640 µg twice daily (b.i.d.) with the option of continuing in a 40-week extension phase (EP). MAIN OUTCOMES MEASURES: Change in morning peak expiratory flow (PEF) from baseline to 12 weeks and safety over 1 year. RESULTS: 365 patients were randomized and 275 continued into the EP. During 12 weeks' treatment, morning peak expiratory flow significantly increased by 16 l/min (p < 0.001) and 14 l/min (p = 0.001) in the 320 and 640 µg b.i.d. groups, respectively. Both doses significantly reduced total asthma symptom scores by 0.29 (p < 0.0001). In both groups, the incidence of adverse effects (AEs) was low and mean cortisol levels in serum and urine were not suppressed during the EP. CONCLUSIONS: Ciclesonide 320 µg b.i.d. sustained lung function and asthma symptoms in patients with severe asthma over 12 weeks' treatment, and maintained lung function during a 40-week EP; ciclesonide 640 µg b.i.d. did not provide additional benefits. Long-term use of ciclesonide was not associated with increased local AEs or negative effects on cortisol levels.