Addex and Indivior to Accelerate Additional GABAB

Geneva, Switzerland, 14 ^th February 2019 – Addex Therapeutics (SIX: ADXN), a leading company pioneering allosteric modulation-based drug discovery and development, and Indivior PLC (LON: INDV) announced today that they will accelerate the optimization and further development of additional GABAB positive allosteric modulator (PAM) compounds for the treatment of addiction under the terms of their global development and commercialization agreement. Following an internal assessment, Indivior decided to stop further evaluation of ADX71441, the lead drug candidate under investigation, and refocus future research on alternative PAM compounds targeting GABAB currently under development within the agreement. Addex will work with its partners to evaluate the future development of ADX71441. “We strongly believe in the GABAB PAM approach and have made significant progress in our ongoing funded research program to discover novel GABAB PAM compounds,” commented Tim Dyer, CEO of Addex. “We will be working closely with the Indvior team to evaluate ADX71441 and decide on its future development.” Under the terms of the agreement signed with Indivior in January 2018, Addex received a $5 million upfront, and a minimum of $4 million research funding to discover novel GABAB PAM compounds. The company could receive up to $330 million of development, regulatory and commercialization milestones and tiered royalties up to double-digit. Addex retains the right to select compounds from the research collaboration for certain indications outside addiction, including Charcot-Marie-Tooth type 1a neuropathy (CMT1A). About GABAB Activation with PAM Activation of gamma-aminobutyric acid subtype B (GABAB) receptor, a Family C class of GPCR, is clinically & commercially validated. The generic GABAB receptor agonist, baclofen, is marketed for spasticity and some spinal cord injuries, and used for overactive bladder (OAB), but it is not commonly used due to variety of side effects of the drug and rapid clearance. Potent, selective oral positive allosteric modulators (PAM) that potentiate GABA responses at the GABAB receptor, rather than an orthosteric agonist at the GABAB receptor like baclofen, only act when the natural ligand (GABA) activates the receptor, therefore respects the physiological cycle of activation. It has been proposed that PAMs produce less adverse effects and could lead to less tolerance than direct agonists (May and Christopoulos 2003; Langmead and Christopoulos 2006; Perdona et al. 2011; Urwyler 2011; Gjoni et al., 2008; Ahnaou et al). The US National Institute on Drug Abuse (NIDA, a division of National Institutes of Health (NIH)) has awarded Addex’s GABAB PAM program a $5.3 million grant to support human studies. About Addex Therapeutics Addex Therapeutics ( www.addextherapeutics.com ) is a biopharmaceutical company focused on the development of novel, orally available, small molecule allosteric modulators for neurological disorders. Allosteric modulators are an emerging class of small molecule drugs which have the potential to be more specific and confer significant therapeutic advantages over conventional "orthosteric" small molecule or biological drugs. Addex' allosteric modulator drug discovery platform targets receptors and other proteins that are recognized as essential for therapeutic intervention - the Addex pipeline has been generated from this pioneering allosteric modulator drug discovery platform. Addex's lead drug candidate, dipraglurant (mGluR5 negative allosteric modulator or NAM) has successfully completed a Phase 2a POC in Parkinson's disease levodopa-induced dyskinesia (PD-LID), and is being prepared to enter registration trials for PD-LID. In parallel, dipraglurant's therapeutic use in dystonia is being investigated. Addex's second clinical program, ADX71149 (mGluR2 positive allosteric modulator or PAM) is being developed in collaboration with Janssen Pharmaceuticals, Inc for epilepsy. In addition, ADX71441 (GABAB receptor PAM) program was awarded a $5.3 million grant by the US National Institute on Drug Abuse (NIDA, a division of National Institutes of Health (NIH)) to support human studies in cocaine addiction and has been licensed to Indivior. Discovery programs include mGluR4PAM, mGluR7NAM, mGluR3PAM and TrkBPAM. Press Contacts: For Addex Therapeutics

Disclaimer / Forward-looking statements: This communication does not constitute an offer or invitation to subscribe for or purchase any securities of Addex Therapeutics Ltd. This publication may contain certain forward-looking statements concerning the Company and its business. Such statements involve certain risks, uncertainties and other factors which could cause the actual results, financial condition, performance or achievements of the Company to be materially different from those expressed or implied by such statements. Readers should therefore not place undue reliance on these statements, particularly not in connection with any contract or investment decision. The Company disclaims any obligation to update these forward-looking statements.