MICA: CB2 agonists as a novel treatment for women with endometriosis-associated pain

Lead Research Organisation: University of Edinburgh
Department Name: Centre for Inflammation Research


Endometriosis is a chronic incurable disease that affects an estimated 176 million women worldwide. This incidence in women of reproductive age is similar to that of diabetes mellitus or asthma (approximately 1.5 million women in the UK). Endometriosis can cause chronic, debilitating, pelvic pain including excessively painful periods and pain with sexual intercourse. Endometriosis costs the UK economy >£9 billion per year in health care and associated costs and has a devastating impact on the health and wellbeing of patients.

Up to 90% of women with endometriosis suffer from 'peritoneal disease' caused by the presence of small pieces of tissue ('endometrium' or womb lining) that have attached onto the wall of the pelvic cavity (peritoneum). Once embedded on the peritoneal wall these 'endometriosis lesions' attract nerves, and immune cells that interact with each other and relay pain messages to the brain. Thre is no cure for endometriosis. Surgical removal of lesions (with its inherent risks) can give temporary relief but symptoms recur in up to 75% of women. Current drugs used as an alternative to surgery include those that have an impact on hormones with unwanted side effects including those resembling a premature menopause (flushes, infertility). Many women also take non-steroidal anti-inflammatory drugs but there is no good evidence that they provide long-term relief and they can have an adverse effect on the gut.

The body is equipped with a sophisticated 'endocannabinoid' system that is part of our natural pain and immune defense network. These endocannabinoids are produced naturally from lipids in the body and they can alter the function of immune cells, such as macrophages and mast cells, dampening down of the body's pain responses. Phyto-cannabinoids, present in cannabis plants, have been widely used as a self-management strategy by patients suffering from chronic non-cancer pain. Cannabinoids are synthetic drugs that have been developed to mimic the beneficial effects of phytocannabinoids without triggering their intoxicating side effects. A new generation of 'smart' drugs targeting one of the cannabinoid receptors (CB2) has been developed as a front line therapy for treatment of chronic pain. To date these drugs have not been tested as a treatment for women with chronic pain due to endometriosis.

We will test a cannabinoid compound developed by Eli Lilly using our novel preclinical model of endometriosis. Using this model we will assess the impact of the cannabinoid on pain behaviours and also on the phenotype of cells within the lesions. The primary purpose of this study is to gather information in preparation for a clinical trial in women with endometriosis.

Technical Summary

Endometriosis is a chronic, incurable, inflammatory disorder affecting ~10% of women of reproductive age half of whom suffer from debilitating pelvic pain. Current treatments include invasive surgeries and hormonal suppression with the latter having undesirable side effects. Peripheral neuro-inflammation plays a pivotal role in activation of both central and peripheral pain pathways in endometriosis. We have shown that nociceptive ion channels are overexpressed in the peritoneum and endometriosis lesions of women with pelvic pain and inflammatory cells are abundant in their lesions. The endocannabinoid system is known to modulate inflammatory/immune mechanisms and pain processing. Endocannabinoids act via CB1 or CB2 receptors; CB1 is responsible for the psychotomimetic side effects of cannabinoids. CB2 has emerged as a key therapeutic target for a range of painful conditions but has not been rigorously tested as a treatment for endometriosis.

We believe treatment with the CB2 receptor agonist LY2828360 offers a novel approach to treatment of women with endometriosis-associated pain. We will evaluate the impact of LY2828360 using a mouse model of endometriosis that replicates key features of the disease in women. A unique feature of our model is the introduction of 'menstrual' tissue into the peritoneum of immune competent mice. This menstrual tissue is cytokine-rich, with high concentrations of matrix remodeling proteins, mast cells and macrophages mimicking the endometrial tissue that is released into the peritoneal cavity leading to the establishment of endometriosis lesions that attract nerves and blood vessels. The lesions formed in recipient (ENDO) mice phenocopy those recovered from patients attending our pain clinic. Following establishment of lesions the ENDO mice exhibit altered pain behaviours (both spontaneous and induced) that can be quantified. The data from this study will be used to support a future clinical trial in women with endometriosis.

Planned Impact

Impact on patients
Endometriosis is an incurable disorder that causes chronic pain. Current treatments include surgical excision or hormonal suppression. National patient organisations report that women want to avoid surgery and to have access to medical treatments with fewer side effects.
We will test the CB2 receptor agonist (LY2828360) as a novel therapeutic option for treatment of pelvic pain. This preclinical study is designed to provide evidence for a subsequent clinical trial which if successful will increase the treatment options for women allowing them to avoid surgery and the side-effects of current medical hormone suppressive therapies.

Impact on the biomedical research community
The results of our project will be communicated via primary publications, accessible review articles, conferences, our websites and presentations to Pharma. We will present at national and international meetings attended by clinicians and researchers involved in endometriosis research and care. At a national level, AWH and PTKS have initiated the formation of an Endometriosis Research Network providing a forum for exchange of ideas/experiences between researchers, health professionals and patients with biannual meetings. The results obtained will also be of particular interest to clinical researchers working on other chronic pain conditions and we will endeavor to disseminate the data to them as appropriate.

Impact on Policy makers
Endometriosis has received relatively little attention compared with other chronic disorders. In 2014, AWH organised an event (>100 attendees, including politicians, clinicians, patients) in the Scottish Parliament to campaign for better care and research across Scotland for women with endometriosis. AWH and colleagues have subsequently established a Scottish Government Endometriosis Short Life working group working closely with Scotland's Chief Medical Officer to take this forward. In addition, AWH and PTKS are members of the Steering Group for the Endometriosis Priority Setting Partnership being managed under the auspices of the James Lind Alliance run by NIHR [http://www.jla.nihr.ac.uk/]. The results of this Initiative will be published and widely disseminated to research organisations, organisations responsible for health care, and policy makers in the UK and Ireland.

Impact on the commercial sector
This project will test the efficacy of a product developed by Eli Lilly and Co. Lilly have already made a very significant investment in this compound including comprehensive toxicity testing in animals and humans. The CB2 agonist LY2828360 was well tolerated but its development as a treatment for osteoarthritic knee pain (the original clinical indication) was discontinued after Phase II clinical trials. Repurposing of this product for treatment of women with endometriosis-associated pain would open up a new market for LY2828360 and for other compounds targeting the endocannabinoid CB2 receptor.
Impact on training and capacity building
This project enables the postdoctoral fellow to gain experience in using a mouse model for preclinical testing using behavioural tests and a range of cell/molecular/protein analyses. The research technician will learn skills in animal handling, surgery, administration of substances and histological analysis. The postdoctoral fellow will gain experience in presenting and defending their research at national and international conferences.

Impact on the public and wider society
We engage with the public via print and a range of digital media including a dedicated webpage [www.exppectedinburgh.co.uk]. PTKS shares information about endometriosis on Facebook and we all participate in public events including the Edinburgh Science Festival.


10 25 50
Description Endometriosis - James Lind PSP
Geographic Reach National 
Policy Influence Type Membership of a guideline committee
Impact Management group of priority setting partnership in endometriosis run under the auspices of the James Lind Alliance. Financial support provided as part of public engagement commitment from grants. Surveys were conducted nationally and results led to publication of a top 10 priority for research - this is being considered by funders including NIHR (phone calls and discussions). High profile publication in the Lancet. Social media activity and engagement with clinical and research community.
Description Ferring Research Innovation Grant
Amount $70,000 (USD)
Organisation Ferring Pharmaceuticals 
Sector Private
Country Switzerland
Start 06/2017 
End 05/2019
Description IMI2-2016-10-03C
Amount € 6,480,000 (EUR)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 04/2018 
End 03/2021
Description MRC Confidence in Concept - Edinburgh
Amount £120,173 (GBP)
Organisation University of Edinburgh 
Sector Academic/University
Country United Kingdom
Start 11/2018 
End 12/2020
Title Mouse model of endometriosis 
Description This was a refinement of a model originally published in 2014 which is being adopted by international groups 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact Adoption of model by a contract research organisation; publication; further funding 
Description Bayer-Schering pharmaceuticals 
Organisation Bayer
Country Germany 
Sector Private 
PI Contribution We have used our expertise and available human cell lines to test the impact of an ERbeta selective agonist on receptor mobility and transcriptional activity
Collaborator Contribution Provided novel ERbeta agonists free of charge - this reagents are not available on the open market and are in development as therapeutics
Impact This reagent has given us novel insight into receptor dynamics that are relevant to reproductive disorders. Informal discussions and an invitation to speak at a workshop in Berlin.
Start Year 2009
Description IMI Grant consortium PainCare 
Organisation European Union
Country European Union (EU) 
Sector Public 
PI Contribution I am leading Work package 10 within the consortium members addressing ' Improving translation in chronic pelvic pain (TRiPP)'. WP10 is focused on improving the translation of new therapies for endometriosis-associated pain by aligning and refining preclinical animal models.
Collaborator Contribution The IMI-PAINCARE Consortium is composed of 40 participants from 14 countries; 6 are EFPIA (European Federation of Pharmaceutical Industries and Associations) participants with strong traditions in pain research and development, 23 are internationally renowned academic and clinical institutions, 5 are specialist SMEs with cutting-edge technologies, 3 are patient organizations and 3 are professional pain/anesthesia societies. The Consortium addresses three important topics: Patient reported outcome measures to improve management of acute and chronic pain (PROMPT); Pharmacological validation of functional pain biomarkers in healthy subjects and animals (BioPain); Improving translation in chronic pelvic pain (TRiPP).
Impact Employment of a posdoctoral fellow for 2 years. Purchase of state of the art in cage monitoring equipment (3R's commitment) Knowledge exchange with leaders in the field of pain including those based in commercial companies (Bayer, Grunenthal)
Start Year 2018
Description Studies on endometriosis associated pain 
Organisation Charité - University of Medicine Berlin
Country Germany 
Sector Academic/University 
PI Contribution Training of visiting PhD student; dissemination of animal model of endometriosis
Collaborator Contribution Provision of human patient samples; PhD student time
Impact Training of PhD student; invitation to give a talk in Berlin for postdoc; publication
Start Year 2013
Description Patient Information Day 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Patients, carers and/or patient groups
Results and Impact This was an event targeted at women who suffer from endometriosis (pain, infertility) and their family members. it was run jointly with the UK patient group Endometriosis UK [https://www.endometriosis-uk.org/] who publicised it via their patient support groups. A speaker from Endometriosis UK introduced the event which consisted of talks from a range of health care professionals (University and NHS staff) as well as researchers. There was time for informal discussion and also for a Q&A. The event was widely publicised on social media and there was a lot of positive feedback from participants.
Year(s) Of Engagement Activity 2019
Description Public lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Patients, carers and/or patient groups
Results and Impact An online lecture which was part of a widely publicised pubiic engagement lecture series.

Tackling the pain of endometriosis | 17 Feb 2021

Hear about our research to tackle a difficult condition that affects one in ten women in the UK.

The cells that line the womb are extraordinary; they grow and shed in a constant cycle of renewal that make pregnancy possible but that can also cause extraordinary pain. Endometriosis is the name given to the condition where cells like those of the womb lining grow outside of the womb in other parts of the body.

Professor Andrew Horne and Professor Philippa Saunders combine their clinical and research expertise and are determined to find new ways to tackle endometriosis. Join us to hear how they work and the approaches they are taking to make life better for the people who live with this difficult condition.
Year(s) Of Engagement Activity 2021
URL https://www.ed.ac.uk/medicine-vet-medicine/news-events/college-events/research-insights/tackling-the...