Grant of second US patent for Chronocort

10th January 2019

Diurnal Group plc

("Diurnal" or the "Company")

Diurnal announces grant of second US patent for Chronocort®

Method of treatment patent provides additional protection in key US market where Chronocort® has already received two Orphan Drug Designations

Diurnal Group plc (AIM: DNL), the specialty pharmaceutical company targeting patient needs in chronic endocrine (hormonal) diseases, announces the US Patent and Trademark Office (USPTO) has granted a second US patent for Chronocort® (modified release hydrocortisone).

US 10,166,194, entitled "Hydrocortisone Controlled Release Formulation", is a patent claiming a method of treatment for adrenal dysfunction, including the diseases congenital adrenal hyperplasia (CAH) and adrenal insufficiency (AI), that delivers hydrocortisone in accordance with a circadian rhythm. The patent provides in-market protection until 2033 and is in addition to the already granted pharmaceutical composition of matter patent US 9,750,704, which provides in-market protection until 2034.

This patent expands the Company's strong exclusivity position in the US, where Chronocort® has already received Orphan Drug Designation for the treatment of both CAH and AI from the US Food and Drug Administration (FDA), which provides the potential for seven years of market exclusivity awarded on approval.

The US is expected to be a major territory for sales of Chronocort®, with CAH and AI collectively estimated to affect 140,000 adult patients and have an addressable market of approximately $1bn.

Martin Whitaker, CEO of Diurnal, commented:

"This second Chronocort® patent provides additional in-market protection in the US, which remains a key target market for Diurnal, in addition to the potential for market exclusivity provided by the award of Orphan Drug Designation for both CAH and AI. With patents now extending protection in the US for both Chronocort® and our paediatric product Alkindi® to 2034, we are confident that, if approved, these products will enjoy a long period of exclusivity in the US market and provide the potential for lifelong treatment of patients with CAH and AI."

Notes to Editors

About Chronocort®

Chronocort® is a modified release preparation of hydrocortisone that has been designed to mimic the circadian rhythm of cortisol when given in a twice-a-day "toothbrush" regimen (last thing at night before sleep and first thing in the morning on waking) to control androgen excess and chronic fatigue in patients with diseases of cortisol deficiency. The first planned indication for Chronocort® is Congenital Adrenal Hyperplasia (CAH) in adults. Chronocort® has been extensively studied in humans having completed four Phase I trials, a Phase II trial in 16 CAH patients in the US in 2014, and a Phase III trial in 122 CAH patients in Europe.

In Europe, Chronocort® has been granted Orphan Drug Designation in the treatment of CAH, which, if confirmed at marketing authorisation, provides market exclusivity for 10 years. The market authorisation of Chronocort® in Europe is anticipated in 2020.

About Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia (CAH) is an orphan condition caused by deficiency of adrenal enzymes, most commonly 21-hydroxylase. This enzyme is required to produce the adrenal steroid hormone, cortisol. The block in the cortisol production pathway causes the over-production of male steroid hormones (androgens), which are precursors to cortisol. The condition is congenital (inherited at birth) and affects both sexes. The cortisol deficiency and over-production of male sex hormones can lead to increased mortality, infertility and severe development defects including ambiguous genitalia, premature (precocious) sexual development and short stature. Sufferers, even if treated, remain at risk of death through an adrenal crisis.

Current therapy for CAH uses a variety of generic steroids (hydrocortisone, dexamethasone and prednisolone). Approximately two-thirds of CAH patients are estimated to have poor disease control, leading to elevated androgen levels. The condition is estimated to affect a total of approximately 47,000 patients in Europe, with over 400,000 in the rest of the world.

About Adrenal Insufficiency

Adrenal insufficiency (AI) is a condition characterised by deficiency in cortisol, an essential hormone in regulating metabolism and the response to stress. The primary symptoms of AI are chronic fatigue and patients are at risk of adrenal crisis and death if they do not have adequate cortisol replacement. AI is either primary or secondary, with primary AI resulting from diseases intrinsic to the adrenal gland and secondary AI resulting from pituitary diseases where there is a failure of stimulation of the adrenal by the pituitary of the signalling hormone ACTH (adrenocorticotropic hormone). AI is estimated to affect over four million patients globally. Chronocort® also benefits from Orphan Drug Designation for AI in Europe.

About Diurnal Group plc

Founded in 2004, Diurnal is a UK-based specialty pharma company developing high quality products for the global market for the life-long treatment of chronic endocrine conditions, including Congenital Adrenal Hyperplasia and Adrenal Insufficiency. Its expertise and innovative research activities focus on circadian-based endocrinology to yield novel product candidates in the rare and chronic endocrine disease arena.

For further information about Diurnal, please visit www.diurnal.co.uk

Date of Preparation: January 2019 Code: CH US-GB-0005