The case against censoring of progression-free survival in cancer clinical trials - A pandemic shutdown as an illustration.

BACKGROUND: Missing data may lead to loss of statistical power and introduce bias in clinical trials. The Covid-19 pandemic has had a profound impact on patient health care and on the conduct of cancer clinical trials. Although several endpoints may be affected, progression-free survival (PFS) is of major concern, given its frequent use as primary endpoint in advanced cancer and the fact that missed radiographic assessments are to be expected. The recent introduction of the estimand framework creates an opportunity to define more precisely the target of estimation and ensure alignment between the scientific question and the statistical analysis. METHODS: We used simulations to investigate the impact of two basic approaches for handling missing tumor scans due to the pandemic: a "treatment policy" strategy, which consisted in ascribing events to the time they are observed, and a "hypothetical" approach of censoring patients with events during the shutdown period at the last assessment prior to that period. We computed the power of the logrank test, estimated hazard ratios (HR) using Cox models, and estimated median PFS times without and with a hypothetical 6-month shutdown period with no patient enrollment or tumor scans being performed, varying the shutdown starting times. RESULTS: Compared with the results in the absence of shutdown, the "treatment policy" strategy slightly overestimated median PFS proportionally to the timing of the shutdown period, but power was not affected. Except for one specific scenario, there was no impact on the estimated HR. In general, the pandemic had a greater impact on the analyses using the "hypothetical" strategy, which led to decreased power and overestimated median PFS times to a greater extent than the "treatment policy" strategy. CONCLUSION: As a rule, we suggest that the treatment policy approach, which conforms with the intent-to-treat principle, should be the primary analysis to avoid unnecessary loss of power and minimize bias in median PFS estimates.

Certolizumab pegol in patients with moderate to severe Crohn's disease and secondary failure to infliximab.

BACKGROUND & AIMS: Patients with moderate to severe Crohn's disease who receive infliximab may experience secondary failure (loss of response and/or hypersensitivity). Data on the utility of switching to certolizumab pegol in these patients are limited. METHODS: A total of 539 patients with active Crohn's disease and secondary failure to infliximab were enrolled in a 26-week trial. Patients received open-label induction with subcutaneous certolizumab pegol 400 mg at weeks 0, 2, and 4. Those in clinical response at week 6 were randomized to certolizumab pegol 400 mg every 2 or every 4 weeks through week 24. The primary end point was response at week 6. Secondary end points included remission at week 6 and response and remission at week 26. RESULTS: At week 6, 334 of 539 patients (62.0%) achieved response and 212 of 539 (39.3%) achieved remission. A total of 329 patients were randomized and received maintenance therapy. At week 26, 39.9% (67 of 168) and 36.6% (59 of 161) of patients in the every-4-weeks and every-2-weeks groups were in clinical response, respectively (P = .55). Corresponding remission rates at week 26 were 29.2% and 30.4%, respectively (P = .81). Serious infections occurred in 9 of 539 (1.7%) and 12 of 373 (3.2%) of patients during induction and maintenance, respectively. A single malignancy (skin carcinoma) occurred in a patient receiving every-4-weeks maintenance therapy. CONCLUSIONS: Response to open-label induction therapy with certolizumab pegol was achieved by 62% of patients with moderate to severely active Crohn's disease and secondary failure to infliximab. Among these patients, certolizumab pegol 400 mg every 4 weeks showed similar efficacy to every-2-weeks dosing for maintenance of response and remission.