Addex regains global GABAB PAM rights after Indivior R&D pullback
Addex Therapeutics has recovered full global rights to all GABAB positive allosteric modulator (PAM) assets developed under its research collaboration with Indivior UK Limited, following Indivior's decision to pare back its research and development activities. The move comes as Indivior's parent company prepares to merge with Supernus Pharmaceuticals, a transaction that appears to have prompted a broader portfolio review at the addiction-focused specialty pharma group.
The returned assets include a development candidate that Indivior had selected and was advancing for substance use disorders, as well as preclinical compounds from the shared research effort. Combined with Addex's own wholly-owned GABAB PAM programme for chronic cough, the company now controls what it describes as one of the broadest portfolios targeting GABAB receptor biology in the industry.
The portfolio and its science
GABAB receptors are metabotropic receptors distributed widely across the central and peripheral nervous systems, where they regulate neuronal excitability and inhibitory neurotransmission. The clinical case for targeting this pathway has been established by baclofen, an approved orthosteric GABAB agonist used in spasticity associated with multiple sclerosis and spinal cord injury, and investigated off-label in alcohol use disorder, cocaine use disorder, and gastro-oesophageal reflux disease.
Baclofen's limitations are well documented: sedation, central nervous system side effects, and a propensity for reduced efficacy with chronic dosing constrain its therapeutic utility. GABAB PAMs offer a mechanistically distinct alternative. Rather than competing with endogenous GABA at the orthosteric binding site, PAMs bind to an allosteric site and potentiate the receptor's response to naturally released GABA. The approach is designed to preserve the activity-dependent character of GABAB signalling, with the theoretical benefit of improved tolerability and a lower risk of tolerance development.
Addex's substance use disorder candidate has completed IND-enabling studies, positioning it for a first-in-human filing when the company secures the resources or a partner to proceed. The chronic cough programme is at an earlier stage, described as ready to begin IND-enabling work.
Strategic options and market context
Chief executive Tim Dyer said the regained rights give the company "the flexibility to advance our broader GABAB PAM portfolio independently," and flagged the possibility of seeking new partnerships in the near term or advancing the programmes further before out-licensing.
The competitive landscape for allosteric modulators of GABA-related targets has grown considerably in recent years. Several academic groups and early-stage biotechs are pursuing similar receptor-selective approaches for neuropsychiatric and pain indications. In the substance use disorder space, the field remains under-served by approved pharmacotherapy, which creates a genuine commercial opportunity for well-differentiated candidates, provided clinical data can demonstrate the tolerability improvements that the PAM mechanism theoretically promises.
Addex is a small, dual-listed company trading on the SIX Swiss Exchange and NASDAQ under the ticker ADXN, and its pipeline is largely pre-revenue. The addition of a Indivior-selected development candidate, which has presumably benefited from that company's regulatory and translational expertise in addiction medicine, could strengthen the attractiveness of the portfolio to a future licensing partner. Investors will be watching for news of such a deal, or for clarity on how Addex intends to fund clinical progression without one.