Holding(s) in Company

Synairgen plc

('Synairgen' or the 'Company')

Holding in Company

Southampton, UK: Synairgen plc (LSE: SNG), the respiratory drug discovery and development company, announces that it was informed on 19 October 2018 that Richard Griffiths, a private investor, now holds 15,391,112 ordinary shares of 1 pence each in the capital of the Company, representing 14.06% of the Company's issued share capital.

For further enquiries, please contact:

Synairgen plc

Richard Marsden, Chief Executive Officer

John Ward, Finance Director

Tel: + 44 (0) 23 8051 2800

finnCap

Geoff Nash, Max Bullen-Smith (Corporate Finance)

Alice Lane (ECM)

Tel: + 44 (0) 20 7220 0500

Consilium Strategic Communications (Financial Media and Investor

Relations)

Mary-Jane Elliott / Sukaina Virji / Laura Thornton

synairgen@consilium-comms.com

Tel: +44 (0) 20 3709 5701

Notes for Editors

About Synairgen

Synairgen is a respiratory drug discovery and development company founded by University of Southampton Professors Stephen Holgate, Donna Davies and Ratko Djukanovic. The business, focused primarily on asthma and COPD, uses its differentiating human biology BioBank platform and world-renowned international academic KOL network to discover and develop novel therapies for respiratory disease. Leveraging its scientific and clinical facilities at Southampton General Hospital, the Company uses in vitro and ex vivo models to progress opportunities into clinical development. The BioBank of human samples is used in these models to increase confidence in the likelihood of successful drug development.

Synairgen is currently running a two-part Phase II trial evaluating SNG001, the Company's wholly-owned inhaled interferon beta (IFN-beta) therapeutic candidate. The Phase II trial, called SG015, has been designed to assess the safety of SNG001 in COPD patients and its clinical benefit in these patients when they have a cold or flu infection, a major driver of COPD exacerbations.

Core to Synairgen's business strategy is the realisation of value via licensing transactions. In August 2015 the Company entered into a collaboration with Pharmaxis to develop an oral LOXL2 inhibitor to reduce fibrosis in patients with idiopathic pulmonary fibrosis (IPF). In December 2017 the collaboration agreement was amended as Pharmaxis took on full responsibility for the programme, with Synairgen receiving a £5 million upfront payment and circa 17% of any future net partnering proceeds from all fibrotic indications.

Synairgen is quoted on AIM (LSE: SNG). For more information about Synairgen, please see www.synairgen.com