Early closure of clinical trials: The experience of the National Cancer Institute of Canada Clinical Trials Group

Abstract

6053 Background: Phase III studies require a significant commitment on behalf of researchers and patients. Closure of a study before the originally planned number of patients have been enrolled may be due to a number of reasons such as poor accrual, information within the study that precludes continuation such as excess toxicity, an interim futility or extreme efficacy analysis or data from outside sources that render the study question obsolete. Methods: We reviewed the phase III activity of our group since inception. Reasons for early closure were classified in the following manner: accrual failure (AF), external information (EI), internal information (II). Studies were grouped by site and time period of study activation to demonstrate any trends over time. Results: 94 phase III studies led by our group were identified from our roster. Reasons for early closure are presented below. Other sites include brain with an early closure due to AF, head/neck where 1 of 3 studies closed due to AF, melanoma where 1 of 3 studies closed due to EI and sarcoma where 2 studies were successfully completed. Several of the studies that closed for accrual failure were nevertheless published either singly or as part of a meta-analysis. Conclusions: Slightly over one third of studies closed prior to achievement of the targeted sample size. Accrual failure continues to be the main cause of early study closure (27/34 or 80%) with a trend towards decreasing frequency of occurrence over time. Emerging data within or external to a study leading to study closure are important but relatively rare reasons for early closure. [Table: see text] No significant financial relationships to disclose.