Low-dose interleukin-2 in patients with stable ischaemic heart disease and acute coronary syndromes (LILACS): protocol and study rationale for a randomised, double-blind, placebo-controlled, phase I/II clinical trial

Introduction Inflammation and dysregulated immune responses play a crucial role in atherosclerosis, underlying ischaemic heart disease (IHD) and acute coronary syndromes (ACSs). Immune responses are also major determinants of the postischaemic injury in myocardial infarction. Regulatory T cells (CD4+CD25+FOXP3+; Treg) induce immune tolerance and preserve immune homeostasis. Recent in vivo studies suggested that low-dose interleukin-2 (IL-2) can increase Treg cell numbers. Aldesleukin is a human recombinant form of IL-2 that has been used therapeutically in several autoimmune diseases. However, its safety and efficacy is unknown in the setting of coronary artery disease. Method and analysis Low-dose interleukin-2 in patients with stable ischaemic heart disease and acute coronary syndromes is a single-centre, first-in-class, dose-escalation, two-part clinical trial. Patients with stable IHD (part A) and ACS (part B) will be randomised to receive either IL-2 (aldesleukin; dose range 0.3–3×106 IU) or placebo once daily, given subcutaneously, for five consecutive days. Part A will have five dose levels with five patients in each group. Group 1 will receive a dose of 0.3×106 IU, while the dose for the remaining four groups will be determined on completion of the preceding group. Part B will have four dose levels with eight patients in each group. The dose of the first group will be based on part A. Doses for each of the subsequent three groups will similarly be determined after completion of the previous group. The primary endpoint is safety and tolerability of aldesleukin and to determine the dose that increases mean circulating Treg levels by at least 75%. Ethics and dissemination The study received a favourable opinion by the Greater Manchester Central Research Ethics Committee, UK (17/NW/0012). The results of this study will be reported through peer-reviewed journals, conference presentations and an internal organisational report. Trial registration number NCT03113773; Pre-results.


GENERAL COMMENTS
This manuscript describes the protocol in study design for a highly innovative approach to immunomodulation in patients with stable or acute coronary artery disease. The premise is using low dose interleukin 2 (IL -2) to raise the regulatory T cell subset in an effort to combat over exuberant adaptive immune responses in atherosclerosis and particularly in acute myocardial infarction. The study rationale is excellent the investigators are superbly qualified to carry out this important early phase trial. The authors should acknowledge the less distinct differentiation and function of regulatory T cells in humans versus mice. (see for example: Shevach EM. Biological functions of regulatory T cells. Adv Immunol 2011;112:137-76.) One issue of concern in the design is the safety monitoring proposal. A "blinded" trial management group (TMG) will apparently initially review adverse events. The chief investigator of the trial and other trial personnel in addition to an unblinded study statistician will comprise the TMG. To preserve the blind of the study and to assure the most rigorous conduct of the trial, shouldn't such analyses be performed by the "independent data monitoring committee." What is the composition of this latter committee? Is it fully independent from the investigative team? Shouldn't this independent group perform the primary safety analysis, and shouldn't an unblinded statistician not work closely with the investigators in adverse event analysis? I would ask the authors to clarify the relationship of the trial management group to the independent data safety monitoring board, as I view understanding this relationship is pivotal to the ability of readers to judge the rigor of the assessment of adverse effects and protection of human subjects.
As therapeutic doses of IL-2 have been associated with profound capillary leak syndrome and IL-2 has long been known to lead to endothelial cell injury, vigilance for adverse effects is particularly important. (See for example: Aronson FR, Libby P, Brandon EP, Janicka MW, Mier JW. Interleukin-2 rapidly induces natural killer cell adhesion to human endothelial cells: A potential mechanism for endothelial injury. J Immunol 1988;141:158-163.)

Nikolaos Frangogiannis
Albert Einstein College of Medicine, USA REVIEW RETURNED 20-Apr-2018

GENERAL COMMENTS
This is a very well-written protocol describing a double blind placebo-controlled trial examining the safety profile and tolerability of low dose IL-2 (aldesleukin) in patients with Ischemic Heart Disease and non-STEMI. An important goal of the study is to determine the dose of IL-2 that increases circulating Tregs by at least 75%. The rationale is well-described. Several minor concerns need to be addressed: The authors would like to thank Prof. Libby for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Our response follows: Reviewer: The authors should acknowledge the less distinct differentiation and function of regulatory T cells in humans versus mice.
Reply: We agree that human regulatory T cells have less distinct differentiation and function and have now commented accordingly in the background section.
Reviewer: A "blinded" trial management group (TMG) will apparently initially review adverse events. The chief investigator of the trial and other trial personnel in addition to an unblinded study statistician will comprise the TMG. To preserve the blind of the study and to assure the most rigorous conduct of the trial, shouldn't such analyses be performed by the "independent data monitoring committee." Reply: The unblinded statistician presents analyses to the blinded TMG in an aggregated and not individualised format to preserve blinding for the other TMG members. This format is often used in early phase clinical trials where dose escalation is primarily based on safety from clinical events. The unblinded and independent data monitoring committee (DMC) will review all adverse events (AEs) and available data before progression to Part B (acute ACS patients). If there are any concerns or uncertainty raised by the TMG then they can refer to the DMC for further assessment. In addition, a DMC meeting is triggered at any stage when two patients within the same group experience any combination of a serious adverse reaction (SAR), an AE that is severe and at least possibly related to the trial drug, or any of the objective stopping criteria listed in the protocol. The DMC will then review all available unblinded data. We have amended the manuscript to provide further clarity and submitted the DMC charter as a supplementary document which outlines procedures and roles in more detail.
Reviewer: What is the composition of this latter committee? Is it fully independent from the investigative team?
Reply: The DMC will be comprised of a fully independent group of clinical researchers with suitable experience in experimental medicine and early phase clinical trials. These researchers are independent from the trial team and have not been involved in the setup or running of this clinical trial.
We have amended the manuscript to provide further clarity and submitted the DMC charter as a supplementary document which outlines procedures and roles in more detail.
Reviewer: Shouldn't this independent group perform the primary safety analysis, and shouldn't an unblinded statistician not work closely with the investigators in adverse event analysis? I would ask the authors to clarify the relationship of the trial management group to the independent data safety monitoring board, as I view understanding this relationship is pivotal to the ability of readers to judge the rigor of the assessment of adverse effects and protection of human subjects.
Reply: To clarify, the TMG and the DMC are completely independent of each other. The Chief Investigator is present at DMC meetings only to explain to the DMC the course of the trial to date. All proceedings of the DMC are conducted privately and independent of the TMG. The unblinded statistician will work closely with the DMC to analyse all available data in an unblinded manner. The DMC will assess the safety of the trial between Part A and Part B, and also be convened if any 2 serious events occur in the same group of patients, and report these findings to the trial group to determine the course of the trial. A separate paragraph explaining this is now included in the manuscript, as well as further clarity elsewhere. We have also submitted the DMC charter as a supplementary document which outlines procedures, roles and relationships in more detail.
Reviewer: As therapeutic doses of IL-2 have been associated with profound capillary leak syndrome and IL-2 has long been known to lead to endothelial cell injury, vigilance for adverse effects is particularly important