Tolerance Bio: Pioneering Immune Tolerance with Thymus-Based Therapies Backed by $20.2M Seed Financing

Tolerance Bio is rapidly emerging as a leader in biotechnology, dedicated to harnessing thymus-based therapies to treat immune-mediated diseases. Under the guidance of Dr. Francisco Leon, MD, Ph.D, the company is revolutionizing the treatment of autoimmune conditions by focusing on thymus regeneration, preservation, and manipulation.

With a $20.2 million oversubscribed seed financing round - an initial closing of $17.2 million recently supplemented with an additional $3.0 million - Tolerance Bio is advancing its research into thymus-derived cell therapies, bringing it closer to clinical trials. The company is developing an allogeneic thymus-induced pluripotent stem cell (iPSC)-based platform, along with other thymus-targeting therapies, to address diseases driven by immune tolerance abnormalities, including cancer, autoimmunity, transplant rejection, infections, immune deficiencies, and allergies.

The seed financing, led by Columbus Venture Partners with support from Criteria Bio Ventures, Sessa Capital, Pacific 8 Ventures, BioAdvance, and Ben Franklin Technology Partners, provides critical funding to accelerate Tolerance Bio's groundbreaking work toward clinical development.

Dr. Francisco Leon is a seasoned biotech entrepreneur with over two decades of success in both academic research and the biopharma industry, particularly in immune tolerance. Before founding Tolerance Bio, Dr. Leon co-founded and served as Chief Scientific Officer at Provention Bio, acquired by Sanofi in 2023 for $2.9 billion. At Provention, he was instrumental in developing Tzield, the first FDA-approved monoclonal antibody for delaying the onset of Stage 3 type 1 diabetes (T1D). Provention's clinical pipeline also targeted other autoimmune diseases like celiac disease and lupus.

Before his work at Provention, Dr. Leon served as CEO and CMO of Celimmune, where he advanced therapies for celiac disease and immune-mediated conditions. His extensive career also includes leadership roles at Janssen Pharmaceuticals, where he spearheaded early-stage clinical development in immunology, as well as positions at Alba Therapeutics, Medimmune, and Bristol-Myers Squibb, driving key initiatives and therapeutic advances.

Now, with Tolerance Bio, Dr. Leon continues to build on his legacy of innovation, advancing novel therapies that have the potential to transform the treatment of immune-mediated diseases.

What is the Thymus and Why is it Important?

The thymus is a small but crucial gland located in the upper chest, just behind the breastbone. It plays a key role in immune system development by producing T-cells, a type of white blood cell that helps defend the body against infections and diseases. Most T-cells are produced before birth and during childhood. By the time you reach puberty, the thymus has produced all the T-cells needed for life, and it gradually shrinks, being replaced by fat.

The thymus's main function is to mature T-lymphocytes, or T-cells. These white blood cells originate in the bone marrow and travel to the thymus to mature and specialize. Once fully developed, they are released into the bloodstream. The thymus is essential for establishing a strong immune system, ensuring protection throughout life.

The Genesis of Tolerance

The story of Tolerance Bio began with a simple cold email that sparked a groundbreaking partnership. Dr. Francisco Leon, a renowned expert in developing disease-modifying therapies for autoimmune diseases, had long been fascinated by the thymus and closely followed advancements in the field. After his successful exit from Provention Bio, Dr. Leon recognized an opportunity to push the boundaries of immune tolerance therapies. That’s when he reached out to Dr. Holger Russ, whose work in induced pluripotent stem cell (iPSC) research had caught his attention.

Dr. Holger Russ, Ph.D., is a pioneering immunologist whose groundbreaking research in regenerative medicine, particularly using iPSCs to treat autoimmune diseases like type 1 diabetes, has gained significant recognition. As an Associate Professor and Scientific Co-Founder of the Diabetes Institute at both the University of Colorado and the University of Florida, Dr. Holger has led several high-profile research aimed at bringing his innovative iPSC technology into clinical practice. It was Dr. Francisco Leon’s unique combination of deep biotech expertise and a proven ability to bring therapies to market that ultimately convinced Dr. Holger to join forces with him.

The mutual respect and shared vision between Dr. Holger Russ and Dr. Francisco Leon laid the foundation for Tolerance Bio. By merging Dr. Holger's pioneering iPSC technology with Dr. Leon's expertise in developing therapies and building successful companies, they set out to revolutionize the treatment of autoimmune diseases. Together, they combined the best of both worlds to create life-changing therapies that could transform patient care.

A World-Class Management Team

To help drive Tolerance Bio’s mission forward, Dr. Francisco Leon strategically recruited several key members from his previous team at Provention Bio. Among them are Justin Vogel, CFO;  Phil Ball, Ph.D., SVP of Business Development and Operations; and Paul Dunford, VP of Translational Science. Each brings deep expertise in biotech development, building a leadership team with a proven track record in advancing innovative therapies.

Dr. Ball shared his enthusiasm about the reunion, saying, "It’s exciting to be working with this team again. We've accomplished a lot together at Provention Bio, and I’m confident we’ll do the same at Tolerance Bio."

A key addition to the Tolerance Bio team is Yeh-Chuin Poh, Ph.D., who joined as VP and Head of Technical Operations. With an impressive background in cell and gene therapy, Dr. Poh has played a pivotal role in securing multiple IND approvals. His recruitment was driven not only by his expertise but also by his strong relationship with Dr. Holger Russ, having collaborated closely in the past. Dr. Poh’s deep understanding of the complex science behind immune tolerance therapies makes him a critical figure in advancing Tolerance Bio’s mission.

“Tolerance Bio’s vision of harnessing the potential of thymus-based therapies to revolutionize immune tolerance is what drew me to this exciting opportunity,” said Dr. Poh. “By combining cutting-edge stem cell technology with a focus on immune regulation, we are poised to make a significant impact on diseases that have long lacked effective treatments.”

Prior to joining Tolerance Bio, Dr. Poh served as Senior Director of Cell Process Development and CMC Lead at Beam Therapeutics, where he played a key role in establishing manufacturing processes for cell therapies. His extensive experience includes leading the development of stem cell-derived pancreatic beta cells at Semma Therapeutics (acquired by Vertex) and co-founding Absolute Nano, a nanomaterials synthesis company acquired by United Science. The founding team was rounded out with the addition of  Christian Blount, MBA, PMP, as Senior Director of Program Management. Blount brings over a decade of experience in program management across biologics and cell and gene therapy, further solidifying Tolerance Bio’s capabilities.

Together, this robust leadership team is pushing Tolerance Bio’s innovative approach to immune tolerance therapies, with a clear focus on developing transformative treatments for autoimmune diseases.

The Formation of Inaugural Scientific Advisory Board

In conjunction with the announcement of its oversubscribed seed funding round, Tolerance Bio proudly unveils its inaugural Scientific Advisory Board (SAB). This esteemed group of global leaders in immunology, cell therapy, and regenerative medicine will provide strategic guidance and scientific expertise as the company advances its mission to develop groundbreaking therapies for autoimmune and metabolic diseases.

Chaired by Dr. Holger Russ, Scientific Co-Founder of Tolerance Bio and a pioneer in stem-cell-derived thymic and beta cell generation, the SAB includes:

• Dr. Megan Sykes, M.D. (Columbia University), is the Michael J. Friedlander Professor of Medicine and Professor of Microbiology & Immunology and Surgical Sciences (in Surgery) at Columbia University. She is Director of the Columbia Center for Translational Immunology, Director of Research for the Transplant Initiative, and Director of Bone Marrow Transplantation Research at Columbia University Medical Center.

• Dr. Camillo Ricordi, M.D., FNAI (University of Miami), is a Professor of Surgery, Distinguished Professor of Medicine, Professor of Biomedical Engineering, and Microbiology and Immunology at the University of Miami (UM), Florida, where he serves as Chief of the Division of Cellular Transplantation, Department of Surgery, Director of the Cell Transplant Center and Director Emeritus of the Diabetes Research Institute (DRI). 

• Dr. Jerome Ritz, M.D (Dana-Farber Cancer Institute and Harvard Medical School),  research focuses on immune reconstitution after hematopoietic stem cell transplantation, cellular therapies, and cancer immunotherapy. From 1996 until June 2024, Dr. Ritz was Executive Director of the Connell and O'Reilly Families Cell Manipulation Core Facility (CMCF) at the Dana Farber Cancer Institute in Boston, MA.

• Dr. Manasi Jaiman, M.D., MPH (Aardvark Therapeutics), is the global, mission-driven Chief Medical Officer of Aardvark Therapeutics, and an expert on cell therapy clinical development. Dr. Jaiman advances breakthrough therapies through the integration of medicine and technology, drawing from 15 years of clinical development, device development, regulatory filings, direct patient care, and scientific research. 

• Dr. Roland Kolbeck, Ph.D. (Spirovant Sciences),  is co-owner and the Chief Scientific Officer of Spirovant and an expert on biologic therapeutics in immune diseases. Dr. Kolbeck is an accomplished biotech executive specializing in respiratory sciences and drug discovery.

The establishment of this SAB underscores Tolerance Bio’s dedication to building a strong scientific foundation for its innovative pipeline. By uniting a team of luminaries across critical fields, Tolerance Bio is well-positioned to drive transformative advancements for patients facing limited treatment options.

Philadelphia: A Strategic Location for Innovation

Located at B+ Labs in Philadelphia, Tolerance Bio is strategically positioned within one of the nation’s most dynamic biotech ecosystems. Philadelphia has long been a hub for life sciences innovation, particularly in cell and gene therapy, with a rich network of academic institutions, research facilities, and biotech companies. The city’s reputation for cutting-edge advancements and its access to top-tier talent make it an ideal base for Tolerance Bio’s operations. While the company currently operates virtually with monthly meetups in Philadelphia, the location serves as a central meeting point for its team members spread across the East Coast. Tolerance Bio envisions growing its presence in Philadelphia in the near future.

Justin Vogel, CFO, emphasizes the city’s advantages, saying, “Philadelphia offers logistical benefits and access to a robust network of cell therapy experts, which will be crucial to our continued growth.” The city's thriving biotech ecosystem provides Tolerance Bio with invaluable opportunities to collaborate with academic and industry leaders, ensuring the company stays at the forefront of immune tolerance research and accelerates the development of its groundbreaking therapies.

In conclusion, Tolerance Bio is at the forefront of a transformative shift in the treatment of autoimmune diseases, leveraging cutting-edge thymus-based therapies and groundbreaking iPSC technology. With its impressive leadership team, including Dr. Francisco Leon’s deep biotech expertise and Dr. Holger Russ’s pioneering work in regenerative medicine, Tolerance Bio is poised to make a lasting impact in the biotech field. Backed by substantial seed financing and supported by a growing network of academic and industry leaders, the company is well-positioned to revolutionize immune tolerance therapies, ultimately providing hope for patients affected by autoimmune conditions. As it continues to innovate and grow, Tolerance Bio’s future looks incredibly promising, with the potential to redefine treatment paradigms for a wide range of diseases that have long lacked effective solutions.