Innovation and Tribulation in the History of Randomized Controlled Trials in Surgery

Despite persistent critiques of the rigor of surgical research, surgeons have actually pursued careful empirical studies for centuries. Their work has enriched not only surgical science but also the development of evidencebased medicine. From conducting landmark controlled trials, to using statistics, alternate patient allocation, randomization, and sham controls, surgeons have long embraced innovative trial approaches and played important roles in the development of key methods of RCTs. However, historical contexts unique to surgery have shaped the implementation of RCTs in this field. Unlike the history of pharmaceuticals, in which substantial research funding has been devoted to testing new drugs before their approval, surgical trials have followed a different trajectory. New operations have repeatedly come into wide use in the absence of RCTs. On many occasions, when established procedures have become controversial, surgeons have then marshaled the resources to conduct RCTs reassessing the operations. Such trials have triggered powerful debates in which proponents of surgical RCTs battled against ingrained practices and preferences. In such cases, RCTs often were not decisive factors in determining the fate of surgical practices but supporting tools that followed and reflected changes in surgical judgment already underway. Surgical trialists also have encountered specific, recurring challenges, especially with the methodological and ethical complexity of blinded and sham-controlled trials. The history of surgical trials thus reveals major contributions from surgeons to the advancement of evidence-based medicine, as well as ongoing challenges. Strengthened and systematic trial support could advance the future of surgical RCTs.

Adaptive design clinical trials: a review of the literature and ClinicalTrials.gov

OBJECTIVES

This review investigates characteristics of implemented adaptive design clinical trials and provides examples of regulatory experience with such trials.

DESIGN

Review of adaptive design clinical trials in EMBASE, PubMed, Cochrane Registry of Controlled Clinical Trials, Web of Science and ClinicalTrials.gov. Phase I and seamless Phase I/II trials were excluded. Variables extracted from trials included basic study characteristics, adaptive design features, size and use of independent data monitoring committees (DMCs) and blinded interim analyses. We also examined use of the adaptive trials in new drug submissions to the Food and Drug Administration (FDA) and European Medicines Agency (EMA) and recorded regulators' experiences with adaptive designs.

RESULTS

142 studies met inclusion criteria. There has been a recent growth in publicly reported use of adaptive designs among researchers around the world. The most frequently appearing types of adaptations were seamless Phase II/III (57%), group sequential (21%), biomarker adaptive (20%), and adaptive dose-finding designs (16%). About one-third (32%) of trials reported an independent DMC, while 6% reported blinded interim analysis. We found that 9% of adaptive trials were used for FDA product approval consideration, and 12% were used for EMA product approval consideration. International regulators had mixed experiences with adaptive trials. Many product applications with adaptive trials had extensive correspondence between drug sponsors and regulators regarding the adaptive designs, in some cases with regulators requiring revisions or alterations to research designs.

CONCLUSIONS

Wider use of adaptive designs will necessitate new drug application sponsors to engage with regulatory scientists during planning and conduct of the trials. Investigators need to more consistently report protections intended to preserve confidentiality and minimise potential operational bias during interim analysis.

Genetic composition of the Bacillus subtilis SOS system

The SOS response in bacteria includes a global transcriptional response to DNA damage. DNA damage is sensed by the highly conserved recombination protein RecA, which facilitates inactivation of the transcriptional repressor LexA. Inactivation of LexA causes induction (derepression) of genes of the LexA regulon, many of which are involved in DNA repair and survival after DNA damage. To identify potential RecA-LexA-regulated genes in Bacillus subtilis, we searched the genome for putative LexA binding sites within 300 bp upstream of the start codons of all annotated open reading frames. We found 62 genes that could be regulated by putative LexA binding sites. Using mobility shift assays, we found that LexA binds specifically to DNA in the regulatory regions of 54 of these genes, which are organized in 34 putative operons. Using DNA microarray analyses, we found that 33 of the genes with LexA binding sites exhibit RecA-dependent induction by both mitomycin C and UV radiation. Among these 33 SOS genes, there are 22 distinct LexA binding sites preceding 18 putative operons. Alignment of the distinct LexA binding sites reveals an expanded consensus sequence for the B. subtilis operator: 5'-CGAACATATGTTCG-3'. Although the number of genes controlled by RecA and LexA in B. subtilis is similar to that of Escherichia coli, only eight B. subtilis RecA-dependent SOS genes have homologous counterparts in E. coli.