Matisse Pharmaceuticals receives INN isupartob sodium recognizing first-in-class drug status for M6229

Geleen, December 11, 2025

Matisse Pharmaceuticals B.V., a clinical stage company developing a medicinal product for the treatment of sepsis, today announced that Matisse’s lead compound M6229, has received the International Non-proprietary Name (INN) isupartob sodium from the World Health Organization. The new class of products ending on the extension -partob, was established by the WHO to define a class of heparin derivatives for histone binders, giving isupartob sodium the recognition as first-in-class product. The INN is a globally recognized, public-domain name that is distinct from a drug's brand name (trademark) and is crucial for clear and safe communication in medicine and pharmacy.

“We are delighted that isupartob sodium has been recognized as a first-in-class therapy through the award of its International Nonproprietary Name (INN), which includes a new and distinctive suffix. This designation reflects Matisse’s leadership in advancing extracellular histone neutralization as a novel therapeutic approach designed to treat sepsis and other histone induced inflammatory indications”, says Marcel Jacobs, CEO of Matisse Pharmaceuticals.

Matisse will adapt this new name in future communication about the lead compound of Matisse.

About Matisse Pharmaceuticals
Matisse Pharmaceuticals B.V. was founded in 2014 in Geleen, the Netherlands. Matisse is dedicated to develop a product portfolio of safe and innovative therapies for disease indications characterized by elevated levels of circulating cytotoxic histones, such as in sepsis.

Matisse’s lead compound isupartob sodium is based on the discovery that in patients suffering from sepsis, proteins called histones are released into the blood stream by the innate immune system which are toxic to cell membranes leading to cell death and release of additional histones. Due to this self-enforcing cascade, sepsis patients are at risk of death from organ failure. The highly negatively charged isupartob sodium binds to the positively charged extracellular histones and inhibits the self-enforcing cascade of increasing histone levels, thereby preventing further organ damage and death.

After two successful clinical trials in healthy volunteers and sepsis patients, isupartob sodium is now entering clinical phase 2 development.  

About sepsis

According to the WHO, sepsis is one of the leading causes of death worldwide. Currently, there is no effective treatment against sepsis approved by regulatory authorities. From the 49 million patients globally suffering from sepsis every year, more than 20% die. Approximately 40% of the sepsis cases are children under the age of 5, with close to 3 million children not surviving sepsis. According to a study by Buchman et al. (2020), published in Critical Care Medicine, sepsis is the most common cause of in-hospital deaths, costing over $62 billion annually in the USA alone.

For more information, please contact:

Marcel Jacobs, CEO
(T) +31 6 575 27 541
(E) info@matissepharmaceuticals.com
(W) www.matissepharmaceuticals.com

Attachments

• 20251211 (NL) Matisse ontvang INN isupartob sodium (final)
• isupartob sodium product picture