Advancing Nucleic Acid Therapeutics by Setting Uniform Standards for Experimental Controls

All scientific experiments need proper controls, and this topic requires particular attention in the case of experiments with nucleic acid therapeutics (NAT), since the chemical modifications used to stabilize them and to improve their pharmacokinetic properties can trigger certain unintended biologic processes. The field has been aware of this since the 1990s, when it became known that for some single-stranded antisense oligonucleotide (ASO) NATs the effects attributed to knockdown of target transcripts through the intended mechanism of action, in fact were due to backbone- and/or sequence-specific inflammatory or antiproliferative effects triggered by the ASO. Recognition of these issues led to calls for the increased inclusion of control oligonucleotides when testing ASO in vitro and in vivo; these principles also should be expected to apply to the field of NAT in general.

In recent years, the NAT field has expanded greatly with the development of new modalities and applications, and with the approval of several new drugs that are providing substantial clinical benefit. The level of investment into the field has increased enormously, leading to an influx of an increasing number of scientists from diverse fields, most of whom are not aware of the history of NAT and the standards for experimental controls that are generally considered essential within the field. This has become apparent to the editors and reviewers of this journal, who have had to reject articles describing experiments lacking the proper control oligonucleotides on a regular basis. During the most recent annual meeting of the Oligonucleotide Therapeutics Society (October 2018, Seattle, WA), the OTS board of directors met and discussed this issue, deciding that it is in the mutual interest of professional societies, companies, and academics working in NAT to play a leading role in setting high standards for our field, and in promoting the adoption of “best practices” to reduce the potential for misleading or inaccurate experimental interpretations. We are pleased to point the reader to the output of this discussion, in the form of the guidelines provided by Gagnon and Corey in this issue.

In summary, the guidelines state the following: 1.

In vitro experiments require two experimental oligonucleotides and two control oligonucleotides (e.g., mismatch or scrambled, all controls should have similar base composition and pattern of chemical modifications to the experimental oligonucleotides).

2.

In vitro dose–response studies should be included for a relevant concentration range covering the full range of activity.

3.

In vivo experiments require at least one experimental and at least one control oligonucleotide (of the same composition and chemistry).

4.

Authors should provide a concise description in the Methods section why their experimental design supports confidence in the robustness and reproducibility of their data.

The guidelines are pragmatic, making suggestions for the minimal amount of controls required to draw scientifically sound conclusions. The guidelines are endorsed by the board of directors of the Oligonucleotide Therapeutics Society (2017–2018 and 2019–2020 terms), and we welcome other societies and individuals to do the same. NAT will require adherence to these guidelines for future submissions.