Indivior and Addex Enter Strategic Collaboration to Accelerate Development of GABAB PAMs for Addiction Disorder Treatments

Slough, UK and Richmond, VA, 3 January 2018 – Indivior PLC (LON: INDV) (“Indivior”) today announced that Indivior UK Limited has entered into a strategic collaboration with Addex Pharma S.A., a wholly-owned subsidiary of Addex Therapeutics Ltd. (SIX: ADXN) (“Addex”), in the field of GABA_B positive allosteric modulators (PAMs). GABA_B PAMs have demonstrated preclinical efficacy and tolerability in animal models for alcohol use disorder (AUD) and cocaine use disorder (CUD)^1,2. The collaboration includes an exclusive global license to lead candidate ADX71441, which is a novel, first-in-class, oral, small molecule and is expected to enter Phase 1 trials in 2018. The collaboration also includes exclusive global license to backup GABA_B PAM compounds, as well as a research collaboration focused on discovering additional GABA_B PAMs. The Addex GABA_B program was recently awarded a $5.3 million grant by the National Institute on Drug Abuse (“NIDA”) to support the development of ADX71441 in CUD³.

Under the terms of the agreement, Indivior is making an upfront payment to Addex of $5 million, and will also invest in research funding over the next two years to discover additional GABA_B PAM compounds commercially-viable to treat addiction. Potential milestone payments to Addex could total $330 million over time if all development, regulatory and sales goals are achieved.

“As part of our leadership position in addiction, among the key priorities we are pursuing is continuing to review and invest in promising new treatments for this chronic and relapsing disease,” said Shaun Thaxter, CEO of Indivior. “Modulation of the GABA_B receptor pathway is an attractive mechanism, particularly for the potential it holds in advancing treatments for AUD and CUD. Further, we are excited about this new strategic collaboration with Addex to discover additional compounds targeting the GABA_B receptor pathway, which will complement the current pipeline efforts we have underway to develop novel treatments for addiction.”

“We believe Addex has the most advanced science in the area of GABA_B allosteric modulation and look forward to rapidly advancing lead compound, ADX71441, into Phase 1 trials,” said Christian Heidbreder, Chief Scientific Officer of Indivior. “As we continue to collaborate with the Addex team, we believe there is great potential for additional compounds to be discovered and developed related to this important mechanism for addiction science.”

Addex’s GABA_B PAMs Program Focused on Addiction

Long-term exposure to drugs of abuse causes adaptive changes in several neurotransmitter systems, including gamma-aminobutyric acid (GABA) receptors. Research has shown that exposure to psychostimulants depresses the normal function of the GABA_B receptor signaling in the mesolimbic dopaminergic system⁴, which plays a role in the positive reinforcing properties of several drugs of abuse and may also contribute to the negative reinforcing effects associated with their withdrawal⁵. Therefore, full agonists aimed at the orthosteric site on the GABA_B receptor have been the target for the development of pharmacotherapies for AUD and CUD².

The efficacy of these full agonists at the orthosteric site on the GABA_B receptor, however, are limited due to tolerance and undesired side effects, including sedation, myorelaxing activity and hypothermia. Unlike orthosteric agonists, positive allosteric modulators (PAMs) work by only enhancing the activity of GABA_B receptors when and where needed physiologically. As such, GABA_B PAMs are expected to have significantly less undesired side effects than full GABA_B receptor agonists and to be suitable for long-term treatment without challenges related to tolerance⁶.

About Indivior

Indivior is a global specialty pharmaceutical company with a 20-year legacy of leadership in patient advocacy and health policy while providing education on evidence-based treatment models that have revolutionized modern addiction treatment. The name is the fusion of the words individual and endeavour, and the tagline “Focus on you” makes the Company’s commitment clear. Indivior is dedicated to transforming addiction from a global human crisis to a recognized and treated chronic disease. Building on its global portfolio of opioid dependence treatments, Indivior has a strong pipeline of product candidates designed to both expand on its heritage in this category and address other chronic conditions and co-occurring disorders of addiction, including AUD and schizophrenia. Headquartered in the United States in Richmond, VA, Indivior employs more than 900 individuals globally and its portfolio of products is available in over 40 countries worldwide. Visit www.indivior.com to learn more.

Forward-Looking Statements

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Media Contacts:

US
IndiviorMediaContacts@indivior.com
+1 804-594-0836

UK
Tulchan Communications
+44 207 353 4200

Investor Contact:

Jason Thompson, Indivior
Vice President, Investor Relations
+1 804-423-8916
Jason.thompson@indivior.com