Pomegra
Neurosterix, the Addex spinout, raised a $105M Series B led by RTW Investments to move its once-daily schizophrenia drug NTX-253 into Phase 2 trials.
Key Takeaways
- Neurosterix closed a $105M Series B on November 12, 2026, led by RTW Investments, to fund Phase 2 work on NTX-253.
- Former Karuna leaders joined: Andrew Miller as executive chair, Edmund Harrigan as director, Stephen Brannan as clinical advisory chair.
- Addex's stake fell from 20% to 8.5%; the company values it at $18.6M. Neurosterix has not disclosed a valuation.
Lead
Neurosterix, a Geneva- and Boston-based neuropsychiatry company, announced a $105 million Series B financing on November 12, 2026. RTW Investments led the round. The money will carry NTX-253, a muscarinic M4 positive allosteric modulator, into Phase 2 development for schizophrenia. The company has not given a Phase 2 start date.
Who Invested in the Round?
RTW Investments led. New investors are Janus Henderson Investors, GV, Ikarian Capital, Affinity Asset Advisors and Dellora Investments. Existing backers Perceptive Advisors and Acorn Bioventures returned.
The round is larger than the Series A, which closed in April 2024 at about $65 million, led by Perceptive, when Addex Therapeutics spun the company out. Neurosterix did not disclose a post-money valuation. Addex's disclosure offers a rough marker: its 8.5% holding is carried at $18.6 million, which implies a company value near $219 million. That figure is derived from Addex's accounting, not a number Neurosterix has confirmed.
What Does NTX-253 Do?
NTX-253 is a highly selective M4 positive allosteric modulator. It does not activate the muscarinic M4 receptor directly. It amplifies the receptor's response to the body's own acetylcholine. The approach aims to treat psychosis without the dopamine blockade behind the movement disorders and metabolic problems of older antipsychotics.
Neurosterix has completed single- and multiple-ascending-dose Phase 1 studies. The company says the pharmacokinetic profile supports once-daily oral dosing. It has not released efficacy data, which Phase 1 studies in this setting are not designed to produce.
Why Did Former Karuna Executives Join?
The company paired the financing with three appointments from Karuna Therapeutics, the developer of Cobenfy, which Bristol Myers Squibb bought. Andrew Miller, Karuna's founder and former head of R&D and lead inventor of Cobenfy, becomes executive chair. Stephen Brannan, Karuna's former chief medical officer, will chair the clinical advisory board. Edmund Harrigan, a former Pfizer senior vice president in regulatory affairs and business development, joins as an independent director.
The hires signal the pitch to investors. Neurosterix is offering a team that has already moved a muscarinic drug through approval, applied to a differently designed molecule. Fred Callori remains CEO.
How Does the Muscarinic Field Look Now?
The field has produced both validation and warnings. The FDA approved Cobenfy in September 2024, the first new mechanism for schizophrenia in about 35 years. Its commercial uptake has been slower than expected, a reminder that clinical novelty does not guarantee prescriptions.
AbbVie's emraclidine, acquired through the Cerevel deal, failed two mid-stage schizophrenia trials and led to $3.5 billion in impairment charges. That failure sits close to Neurosterix's own strategy: emraclidine is also an M4 positive allosteric modulator. Investors funding NTX-253 are betting that the class failed on one molecule's properties rather than on the biology. Neurocrine Biosciences is also working in the muscarinic space, so the field is crowded as well as unproven.
What Else Is in the Pipeline?
The round also supports two other programs. NTX-529 is a second M4 PAM aimed at psychosis and mood disorders. NTX-819 is an mGlu7 negative allosteric modulator, described by the company as potentially first-in-class, for mood and anxiety disorders.
Neurosterix reports more than 100 patent filings, a library of over 80,000 compounds and more than 200 CNS-relevant functional assays. That platform is the basis for its claim that it can generate selective allosteric modulators beyond the lead asset. Spreading $105 million across three programs also means Phase 2 for NTX-253 will not absorb every dollar.
What Does the Round Imply?
Neurosterix raised its Series B after emraclidine's failures, not before them, and the syndicate is made of specialist healthcare funds plus GV. That suggests investor interest in M4 modulation has survived the setback, with the bet shifting from the mechanism to the quality of each molecule. The Karuna appointments reinforce that view.
The caveat is that no efficacy signal exists yet. A Phase 2 readout in schizophrenia would be the first test of whether NTX-253 separates from placebo, and the company has not said when patients will be dosed.
Outlook
Neurosterix now holds funding to run mid-stage development of NTX-253 and advance two other programs, backed by an executive bench with direct Cobenfy experience. The Phase 2 start date, trial design and any valuation disclosure are the open items. Efficacy data, not financing, will determine whether the M4 PAM approach recovers from emraclidine's failure.
