Selective CYP11B1 inhibitors as a novel treatment option for endogenous cortisol excess

Steroidogenesis is the process by which cholesterol is converted to biologically active steroid hormones within the adrenal glands with different steroidogenic enzymes enabling the process. This includes several steps guiding to three pathways that produce separate steroid hormones: those important for regulating salt levels, sugar levels and those responsible for sex differentiation and development. Steroids regulating sugar levels are called glucocorticoids and cortisol is the major glucocorticoid in humans. There are a number of conditions in which the adrenal glands produce too much of cortisol. Due to prolonged exposure to excess cortisol, patients will develop a characteristic set of specific signs and symptoms termed 'Cushing's syndrome'. In this rare condition, patients suffer from severe long-term health consequences such as obesity, high blood pressure, diabetes, cognitive disorders and heart disease. If untreated, life expectancy is significantly reduced, with heart disease and infections being the commonest causes of death. If diagnostic tests indicate mild or moderate excess Cortisol production, but no immediate signs and symptoms are visible, the condition is called subclinical Cushing's syndrome. This is much more frequent (around 5-10 in 1000 people will suffer from it) and although no immediate signs are visible, those patients will still develop severe long-term health problems. Sadly, it can be very complicated to effectively treat those conditions. If it is clearly a tumour that produces the excess Cortisol then surgery is the treatment of choice. In all other cases and especially in subclinical Cushing's syndrome, we usually aim for lifelong drug treatment. Unfortunately, to date the only options are drugs with limited effectiveness and negative side effects. The drugs we currently use most frequently decrease Cortisol production by blocking enzymes involved in the process. But, as steroidogenic enzymes are very similar to each other in their structure, they block several enzymes and therefore influence all three pathways of steroidogenesis, which is a major cause for side effects. The final step in the production of cortisol is enabled by an enzyme called CYP11B1. This enzyme is not involved in other steroidogenic pathways. We therefore aim to develop a very capable inhibitor of CYP11B1 as a new and improved drug treatment option for Cushing's syndrome and subclinical Cushing's syndrome. The more potent such a drug is, the better its dose can be adjusted to the individualised needs of a patient. We will therefore be able to target all forms from mild to severe cortisol excess. In order to limit the side effects this drug should not inhibit other steroidogenic enzymes. Especially CYP11B2, the most important enzyme for production of salt regulating steroids, is almost identical in its structure. Through this project, I aim to prove that selective inhibition of CYP11B1 is a superior drug treatment option to reverse the health consequences of cortisol excess. I will demonstrate this in a mouse model of Cushing's syndrome. Subsequently, I will explore the effects and side effects of eight selective CYP11B1 inhibitors and select the most promising one to be taken forward for clinical development, e.g. to be taken forward to a pharmaceutical company for further drug development. I anticipate that my study will ultimately help the clinician to better personalise treatment for each individual patient with cortisol excess and improve their long term outcomes.

Aims: Perform a systematic preclinical testing of the most promising selective CYP11B1 inhibitors to develop a superior drug treatment option for endogenous Cortisol excess.
Objectives: 1: Use of a rodent model to provide proof-of-principle for in vivo efficacy of selective CYP11B1 inhibition for the treatment of endogenous cortisol excess. 1.1: In vitro identification of selective murine Cyp11b1 (mCyp11b1) inhibitors. 1.2: In vivo proof-of-principle in a murine model of endogenous cortisol excess 2: Translation to human: Identification of the most promising inhibitor compound for future in vivo studies in human. 2.1: Evaluation of selected inhibitor compounds in different in vitro models. 2.2: Initial assessment of biodistribution and bioavailability for the most promising inhibitor compound.
Methodology: In preliminary work I have identified eight novel selective inhibitors of human CYP11B1. To demonstrate that selective inhibition of CYP11B1 successfully reverts the adverse metabolic consequences of endogenous glucocorticoid excess, I will select one compound that selectively inhibits the murine Cyp11b1 to be applied in a proof-of-principle mouse model of Cushing's. The selective human CYP11B1 inhibitors will then be evaluated in different in vitro models to assess their effect on residual steroidogenesis, steroidogenic enzyme expression and potential toxic effects. I will subsequently perform an initial assessment of bioavailability for the most promising compound in a commercially available assay to estimate metabolic stability and perform an in vivo assessment of biodistribution in rats.
Scientific/Medical Opportunity: For endogenous cortisol excess, a highly effective drug treatment option that can be tailored to the individualised needs of every patient is strongly needed. My study will ultimately lead to a first-in-man testing of a novel CYP11B1 inhibitor as a new treatment option that can be tailored to the degree of cortisol excess.

Endogenous Cortisol excess is associated with severe morbidity and mortality and affects more than 79/100,000 individuals when considering all stages of possible disease- from mild to severe hormone excess. Early and effective treatment is crucial to avoid long-term health consequences. If surgery is not feasible, life-long medical therapy is the treatment of choice but the drug treatment options currently available are of limited efficacy and associated with severe side-effects.
The aim of my study is to develop a novel and improved drug for the treatment of endogenous cortisol excess. We are aiming for a very potent compound, so doses can be titrated to the individualised needs of every patient, with a favourable side effect profile.
Through my project, I aim to gain better insight into the complex adrenal steroidogenesis pathway and help to understand consequences of selective inhibition of steroidogenic enzymes.
We aim to ensure that the research in this proposal will impact directly or indirectly onto the following groups:
(a)Academia: This study has the potential to further our understanding of the complex adrenal steroidogenesis pathway and the impact of altering it by inhibitory compounds. We will present the results of this proposal at local, national and international meetings and publish the proposed research in leading endocrine and general medicine high-impact international journals.
(b)Clinicians: An improved drug treatment option will will greatly ease clinicians' decision making and subsequently result in patients receiving appropriate treatment in a timely manner. The study team is strongly embedded in a firm international collaborative network and regular exchange is granted through meetings with clinical focus. We will also build on the collaborations we already have through the formal alliance of the University of Birmingham with University Hospital Birmingham and Heart of England Foundation Trust.
(c)Industry: Both the College and the University have very active and effective groups which oversee the commercialisation of research. Within the College, the dedicated Technology Transfer Team regularly meet Professor Wiebke Arlt (who already has several patents and industrial support for her research) to assess IP and potential commercial development strategies. The University's own dedicated commercialisation company, Alta Innovations (www.alta.bham.ac.uk) will support the patent process and drive licensing and spin-out opportunities. Finally, there is regular exchange with surrounding NHS trusts. This provides a seamless support service from academic innovation through commercial output and into clinical practice.
(d)General Public: This research aims to enhance to awareness of long-term health consequences even in only mild cortisol excess. All publications will follow the University of Birmingham open-access policy and will be made available via upload into the University of Birmingham's Research Archive (UBIRA), a free, open-access journal repository, which greatly enhances the visibility of our work. We will also use our Institute's and University's websites to publicise our results to the general public. The UoB press office and the College's marketing and communications manager regularly ensure publication of articles relating to scientific innovation and dissemination of information to the public through regular press releases.
(e)Patients: The general aim of the proposed research is to provide an improved drug treatment options for endogenous cortisol excess so patients will obviously directly benefit from the project. My study will ultimately help the clinician to better personalise treatment for each individual patient with cortisol excess and improve their long term outcomes. We will build on involvement of affected parties in the design of subsequent studies and therefore intend to work directly with patient groups and seek contact through dedicated patients' events.