About
oncostellae

Our Focus OST-122

Oncostellae is a clinical-stage biopharmaceutical company focused primarily on advancing OST-122, a differentiated, gut-restricted oral small molecule for inflammatory bowel disease (IBD).

OST-122 inhibits JAK3, TYK2, and ARK5 and was specifically engineered to deliver potent anti-inflammatory activity directly within the gastrointestinal tract while minimizing systemic exposure — preserving the rapid efficacy and oral convenience of JAK inhibition while addressing the class’s key safety limitation.

Following a successful randomized, double-blind, placebo-controlled Phase IIa study in moderate-to-severe ulcerative colitis — where OST-122 demonstrated clinical remission in 22% of patients versus 0% on placebo after just 28 days of treatment, alongside a favorable safety profile — the program is now Phase IIb-ready.

Oncostellae is actively seeking strategic partners and investors to advance OST-122 through Phase IIb and beyond, and is open to licensing, co-development, and investment structures.

Management Team

Guido Kurz, PhD
Chief Executive Officer

Guido Kurz is a pharmaceutical R&D executive and entrepreneur with more than 30 years of international experience in drug discovery and development. He received his academic training in Organic Chemistry at the Technical University of Munich, Caltech, and the University of Strasbourg. His career includes senior R&D positions at Pharmacia Corporation as well as leadership roles in biotechnology companies and startups across Europe. His expertise spans the drug development continuum, from early-stage discovery and medicinal chemistry to preclinical and clinical translation. Since 2014, Guido has served as CEO of Oncostellae, where he leads the company’s scientific and development programs and oversees its financing and business development activities.

John E. Butler Ransohoff, PhD
Vice President, Business Development

John Butler is a pharmaceutical R&D executive with more than 37 years of experience spanning drug discovery, development, innovation management, and strategic partnering. Prior to Oncostellae, he built a distinguished career at Bayer, holding senior leadership roles including Global Head of R&D Coordination. At Oncostellae, he leads business development, strategic partnerships, and corporate value creation. He holds a PhD in Organic Chemistry (Max-Planck-Institute, Heidelberg) was a Research Fellow at Rockefeller University and serves since 2014 as Visiting Professor of Immunology at City-Saint Georges’ University of London.

Julio Castro, PhD
Chairman of the Supervisory Board

Julio Castro is founder, principal investor, and Chairman of the Supervisory Board of Oncostellae. He brings extensive experience in biotech entrepreneurship, investment strategy, and capital raising, with a strong track record in building and supporting innovative life sciences companies.

He holds a PhD from the University of Konstanz, Germany, and has held senior roles in medicinal chemistry and R&D at Bayer, Almirall, and Oryzon Genomics. In addition to contributing to multiple drug discovery programs and patents across several therapeutic areas, he has founded a number of biotechnology companies, including Oncostellae, Medibiofarma, Origo Biopharma, Medchemfarma, and Iteria Biopharma.

Agustí Soler
Vice President, Finance

Agustí Soler is Vice President, Finance at Oncostellae and a finance and investment professional with more than 20 years of experience across startups, venture capital, and life sciences. He brings extensive expertise in corporate finance, fundraising, financial due diligence, and valuation, and has worked closely with entrepreneurs, investors, and deep-tech and life sciences companies.

At Oncostellae, he supports the company’s financing strategy, financial operations, and value creation activities.