(CRTH2) Antagonists in Asthma: a Systematic Review and Meta-Analysis Protocol AUTHORS Liu, Wei; Min, Jie; Jiang, Hongli; Mao, Bing

BMJ Open: first published as 10.1136/bmjopen-2017-020882 on 20 April 2018. Downloaded from PEER REVIEW HISTORY

BMJ Open publishes all reviews undertaken for accepted manuscripts. Reviewers are asked to complete a checklist review form (http://bmjopen.bmj.com/site/about/resources/checklist.pdf) and are provided with free text boxes to elaborate on their assessment. These free text comments are reproduced below.

ARTICLE DETAILS

TITLE (PROVISIONAL) Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTH2) antagonists in asthma: a systematic review and meta-analysis protocol AUTHORS liu, wei; Min, Jie; Jiang, Hongli; Mao, Bing

VERSION 1 – REVIEW

REVIEWER Hugo Farne Imperial College London United Kingdom REVIEW RETURNED 05-Jan-2018

GENERAL COMMENTS This is an interesting proposal as the findings have indeed been contradictory.

My major comment is about the language - this paper would benefit significantly from proof-reading by a native English speaker (e.g. first para page 8). http://bmjopen.bmj.com/ Other comments:

Strengths & Limitations (p5): - As there are no head-to-head trials of CRTH2 antagonists, subgroup analyses cannot directly assess the efficacy of CRTH2 antagonists relative to each other - By having no cut-off in terms of minimum duration of

treatment (e.g. 12 weeks or 16 weeks), the study may include trials on September 28, 2021 by guest. Protected copyright. that were underpowered, which in turn may dilute any effect – I would note this.

Introduction (p7) - CRTH2 is also expressed on Type 2 Innate Lymphoid Cells (ILC2s) - CRTH2 is not expressed on mast cells (except intracellularly, with unknown function) so production of cytokines from mast cells is not a consequence of PGD2 binding to CRTH2 on mast cells - The rationale for the CRTH2 receptor as a drug target in asthma is not explained fully. The receptor CRTH2 is of particular interest because its binding stimulates Th2 and ILC2 cells to release the ‘type 2’ cytokines IL-4, IL-5 and IL-13. Therapies targeting type 2 inflammation have been successfully developed for diseases with this underlying pathophysiology, including asthma, atopic dermatitis and allergic rhinitis. In asthma, monoclonal antibodies directed against IL-5 have been shown to be highly efficacious, particularly in

BMJ Open: first published as 10.1136/bmjopen-2017-020882 on 20 April 2018. Downloaded from

reducing exacerbations (less so in terms of lung function and symptoms), and are widely licensed and included in guidelines globally. Dupilumab, which targets the α subunit of the IL-4 receptor that is required for IL-4 and IL-13 signalling, is in advance clinical development with highly promising results. See Farne et al 2016 “Are emerging PGD2 antagonists a promising therapy class for treating asthma?” https://www.ncbi.nlm.nih.gov/pubmed/27690668

Eligibility criteria (p9) - Interventions – probably worth explicitly stating that allergen challenge models will be excluded (some of the trials utilise this)

Data synthesis & analysis - (p16) Comment rather than a critique, but for subgroup analysis of continuous variables, it is highly unlikely there will be 10 studies reporting these - (p17) What is the sputum eosinophil cut-off of ≥2% based on? Is this the same regardless of whether participants are on ICS (which will suppress sputum eosinophils) or not? Best supported by a reference.

REVIEWER Ian Hall University of Nottingham REVIEW RETURNED 09-Jan-2018

GENERAL COMMENTS This manuscript describes a proposal to undertake a systematic review and meta analysis of the efficacy of oral CRTH2 antagonists in asthma, with the primary endpoint being FEV1. As there have been a number of clinical trials looking at agents from this class of drugs there would be some value in a systematic review and meta analysis. As far as I am aware there hasn't been a meta analysis undertaken to date. However, this may not be straightforward to

interpret for the following reasons: http://bmjopen.bmj.com/

1 the first issue is that the different antagonists developed for clinical studies in asthma have somewhat different pharmacological characteristics, with some being relatively selective for CRTH2 alone but others having additional activity, which may make pooling of data problematic to interpret. 2 there have been a relatively small number of blinded, randomised

clinical trials published which may make it difficult to look at study on September 28, 2021 by guest. Protected copyright. heterogeneity effectively 3 studies have been published in patient groups both on and off other medication (especially inhaled steroids) and when stratified for this the number of informative studies will be further reduced for each analysis 4 I don't think there will have been enough studies which have looked at sputum eosinophilia to allow a stratified analysis to be undertaken (it may be possible to look at peripheral blood eosinophil counts) 5 Not all of the larger relevant studies are referenced in the protocol although they should be picked up using the search methodology suggested.

VERSION 1 – AUTHOR RESPONSE

The comments and responses are listed as follows one by one:

BMJ Open: first published as 10.1136/bmjopen-2017-020882 on 20 April 2018. Downloaded from 1. To the editor comments: - Please complete and include a PRISMA-P checklist, ensuring that all points are included and state the page numbers where each item can be found. The completed PRISMA-P checklist has been included as supplementary file 2 - Please include the dates of the search in the abstract. The date of search has been added in the abstract part: .“.....and Scopus will be searched from inception to December 30, 2017 for eligible RCTs.....” - Please include the start search date in the methods section - was this from inception? The start search date has been included in the method part: “...... and Scopus for abstracts and full articles from inception to December 30, 2017” - Please include an example of the full search strategy as a supplementary file. An example of the search strategy has been included as a supplementary file 1

2. To the reviewer 1 comments: - My major comment is about the language - this paper would benefit significantly from proof- reading by a native English speaker (e.g. first para page 8). The manuscript has been read by a native English speaker, and the grammatical problems have been improved. - Strengths and limitations(p5): The two items you mentioned have been included in the Strengths and limitations section. Introduction (p7): - CRTH2 is also expressed on Type 2 Innate Lymphoid Cells (ILC2s) ILC2s and relevant reference have been added. - CRTH2 is not expressed on mast cells (except intracellularly, with unknown function) so production of cytokines from mast cells is not a consequence of PGD2 binding to CRTH2 on mast cells Indeed, human MC express DP2 intracellularly rather than on their surface, and the function of DP2 in human MC is different than in other immune cells such as Th2 cells, eosinophils and basophils where

it is expressed on the cell surface and induces Th2 cytokine and/or granule associated mediator http://bmjopen.bmj.com/ release. I already delete the content about MC in this part. - The rationale for the CRTH2 receptor as a drug target in asthma is not explained fully…… Revisions have been made in the Introduction part according to the paper from Farne et al. Eligibility criteria (p9) - Interventions – probably worth explicitly stating that allergen challenge models will be excluded (some of the trials utilise this) "Studies utilising allergen challenge models will be excluded" has been explicitly stated. on September 28, 2021 by guest. Protected copyright. Date synthesis and analysis - (p16) Comment rather than a critique, but for subgroup analysis of continuous variables, it is highly unlikely there will be 10 studies reporting these The sentences have been deleted. - (p17) What is the sputum eosinophil cut-off of ≥2% based on? Is this the same regardless of whether participants are on ICS (which will suppress sputum eosinophils) or not? Best supported by a reference. Yes, no matter the patient is on or off ICS, 2% is used as cut-off to define sputum eosinophilia. Studies have indicated that a proportion of sputum eosinophils greater than 2% of all sputum inflammatory cells can distinguish individuals with eosinophilic asthma from healthy individuals and those with noneosinophilic asthma. The relevant reference is added.

3. To the reviewer 2 comments: - the first issue is that the different antagonists developed for clinical studies in asthma have somewhat different pharmacological characteristics, with some being relatively selective for CRTH2 alone but others having additional activity, which may make pooling of data problematic to interpret.

BMJ Open: first published as 10.1136/bmjopen-2017-020882 on 20 April 2018. Downloaded from I agree with you completely, so that's why in this review we will further analyse the results by subgroup analysis according to the type of CRTH2 antagonists, e.g. we may include three studies using OC459, and two studies using setipiprant, we will analyse the effect and safety of each drug separately by subgroup analyses. Besides, inspired by your comment, we added one more confounder expected to result in heterogeneity: Pharmacological characteristics of CRTH2 antagonists: CRTH2 selective antagonists alone or non-selective CRTH2 antagonists including CRTH2/DP dual antagonists and CRTH2/TP dual antagonists. - there have been a relatively small number of blinded, randomised clinical trials published which may make it difficult to look at study heterogeneity effectively During the search strategy development and modification in this protocol, we did some preliminary searches in one of the major databases, and yielded more than ten relevant blinded, randomised clinical trials. We think it may be enough to analyse the results and the heterogeneity. - studies have been published in patient groups both on and off other medication (especially inhaled steroids) and when stratified for this the number of informative studies will be further reduced for each analysis We changed the sputum eosinophil count to the blood eosinophil count as you suggested. In the Intervention section we specified the inclusion criteria. Consecutive use of conventional therapy including inhaled steroids is allowed in the studies that qualified for this review but medications that have influence on blood eosinophils are not permitted. Inhaled steroid will have little effect on the blood eosinophils. Therefore, we will not do the subgroup analysis based whether patients are on ICS or other medication. - I don't think there will have been enough studies which have looked at sputum eosinophilia to allow a stratified analysis to be undertaken (it may be possible to look at peripheral blood eosinophil counts) Actually, we also had the same consideration when we designed the protocol. As there were good correlation between sputum eosinophil count and blood eosinophil, we made revisions according to your suggestion and changed the sputum eosinophil count into peripheral blood eosinophil count. Hope it will yield more studies.

- Not all of the larger relevant studies are referenced in the protocol although they should be http://bmjopen.bmj.com/ picked up using the search methodology suggested. Thorough revision was made and more relevant papers were referenced in this manuscript.

VERSION 2 – REVIEW

on September 28, 2021 by guest. Protected copyright. REVIEWER Ian Hall University of Nottingham REVIEW RETURNED 12-Feb-2018

GENERAL COMMENTS Most of the comments I raised have been adequately addressed. I remain concerned about whether or not there will be enough comparable studies to allow the subgroup analyses to be undertaken, but on balance I think it is reasonable to go ahead. Some of the English could do with further improvement although in general it is clear enough to understand what is intended.

REVIEWER Hugo Farne Imperial College London, UK REVIEW RETURNED 27-Feb-2018

GENERAL COMMENTS Thank you to the reviewers for attempting to address my previous comments, most of which have been covered.

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However the quality of the English remains below the standard I would consider acceptable for publication. I have gone through the draft in more detail and provide a scanned version with comments.

Also on page 6 - as far as I know, no study of a CRTH2 antagonist has demonstrated any safety concerns, and none had to be discontinued (certainly not the two that you reference following your statement).

I remain unconvinced that there will be insufficient comparable studies for any of the subgroup analyses, but I suppose the authors can run the search and see what comes up.

- The reviewer also provided a marked copy with additional comments. Please contact the publisher for full details.

VERSION 2 – AUTHOR RESPONSE

Response to reviewers

Dear reviewers,

Thank you very much for your review and comments again. All your suggestions and comments are very useful for us. The English had been further improved with the great help from Dr. Hugo Farne. We did comprehensive revisions in the draft.

The responses to some comments from Dr. Hugo Farne are listed below: http://bmjopen.bmj.com/

1. “Dozens of orally bioavailable CRTH2 antagonists……”—— Don’t think that many

We found 26 CRTH2 antagonists, of which 21 had been studied in clinical trials in asthmatics (OC000459/OC459, QAW039/fevipiprant, AZD1981/AZ1981, ramatroban, BI 671800, AMG 853, ACT-129968/KYTH-105/setipiprant, ARRY-502, ADC-3680, TASP0376377, MK-7246, MK-1029,

AM211, BI 1021958, AP768, AM461, AZD8075, AD5985, QAV680, OC002417/ATX 2417/OC-2417, on September 28, 2021 by guest. Protected copyright. RG7185). For the other 5 compounds (TM30089, AZD6430, AM156, AM206, ASP5642), no clinical data has been found yet. Therefore, we replaced the phrase “Dozens of” with “More than twenty”.

2. Have any studies shown “efficacy of CRTH2 antagonist in reducing exacerbations”?

A recent study reported by Bateman, et al. 1 showed reductions of asthma exacerbations in fevipiprant group.

They described a dose-ranging, parallel-group Phase II study of fevipiprant in patients with uncontrolled, allergic asthma (n=1058 randomized), and found that there was a numerical reduction in exacerbations with fevipiprant treatment compared with placebo.

BMJ Open: first published as 10.1136/bmjopen-2017-020882 on 20 April 2018. Downloaded from 3. “As far as I know, no study of a CRTH2 antagonist has demonstrated any safety concerns, and none had to be discontinued (certainly not the two that you reference following your statement”

I am so sorry for the mistakes in the reference.

Safety and tolerability have been reported in a variety of clinical CRTH2 antagonists. Most of them have been reported to be safe and well tolerated in asthma treatment such as OC000459, fevipiprant, BI 671800 and so on. However, some clinical trials for CRTH2 antagonists had been disclosed and main reasons reported are low efficacy, undesirable tolerability and PK profiles. For example, Amgen discontinued the development of AMG853 because that no effect at improving ACQ, asthma symptoms or lung function was found in Phase II trial (NCT01018550). AstraZeneca disclosed Phase I trial of AZD5985 due to tolerability issues (NCT00967356) and a Phase I trial of AZD8075 after turbidity in urine was reported in 4 out of 8 healthy volunteers (NCT00787072). Roche discontinued RG 7185 in Phase I without reporting any specific reasons. MK7246 was discontinued because of high intersubject variability. Studies on AM211 were disclosed after high intersubject variability and enterohepatic recirculation were reported. http://bmjopen.bmj.com/ on September 28, 2021 by guest. Protected copyright.