Promentis Pharmaceuticals Inc., a Milwaukee-based company developing therapies for central nervous system disorders (CNS), has completed a $26 million series C financing to help it advance its lead compound, SXC-2023, through phase II proof of concept in an undisclosed CNS indication for which it said no drug is currently approved in the U.S. or Europe. It expects the study will take about 12 months from start to finish. An investigational new drug application for SXC-2023 maybe filed later this year to allow it to move into phase I by the end of 2017 or early in 2018, CEO Klaus Veitinger told BioWorld Today.

The candidate is a small molecule designed to engage the Xc-system, a CNS target located predominantly on astrocytes, star-shaped glial cells that regulate the transmission of electrical impulses in the brain.

"Most companies target the neuron via agonists and antagonists. At Promentis, we target the astrocyte in a sense," Veitinger said, noting that while receiving quite a bit of attention in the academic sphere, the Xc-system hasn't gained much attention in industry, he said. When driven, it draws the amino acid cysteine into the astrocyte and expels presynaptic glutamate, generally considered to be the most important transmitter for normal brain function. Imbalances of glutamate have been implicated in a variety of CNS disorders, especially psychiatric disorders, from schizophrenia and bipolar disease to impulse control disorders, such as gambling addiction.

"The thought is that by restoring this imbalance, you can have an efficacious drug, but equally important, a drug that doesn't agonize or antagonize something, which can often cause side effect issues," said Veitinger. CNS drugs with minimal side effects, such as the epilepsy medicines gabapentin or levetiracetam, are rare in the market and prized even in cases where efficacy in moderate, he said.

Orbimed, F-Prime Capital Partners (formerly Fidelity Biosciences) and Aisling Capital led the investment. All three are adding representatives to the company's board, including Veitinger, who in addition to leading Promentis is a venture partner at Orbimed. Existing investors, including Black Pearl GmbH (formerly Black Horse Investments GmbH), Marquette's Golden Angel Network and individual investors, also participated in the round.

With this financing, Promentis has raised more than $31 million to date, including a 2013 series B financing of about $3 million and a $2 million series A round.

Founded in 2007 by two Marquette University scientists, David Baker and John Mantsch, the company is built in part on significant research regarding glutamatergic imbalances and oxidative stress led by the duo. Key to their efforts as well has been expertise drawn from veterans of Schwarz Pharma AG, where Veitinger worked on CNS drugs such an Neupro, a rotigotine transdermal patch for Parkinson's disease. Daniel Lawton, president of Promentis, is another Schwarz alum. And Patrick Schwarz-Schuette, who ultimately sold Schwarz to UCB for about $5.6 billion, serves on Promentis' board.

In the future, Veitinger said, if the phase II proof-of-concept study is positive, Promentis will have "a lot of options" and be able to begin to think bigger, in terms of financings, collaborations or transactions.