The Cancer Research Institute (CRI) mourns the passing of Susumu Tonegawa, PhD, Nobel laureate, pioneering molecular biologist, and longtime member of CRI’s Scientific Advisory Council. Dr. Tonegawa passed away on July 11, 2026, at the age of 86.
Dr. Tonegawa transformed our understanding of the immune system through one of the most important discoveries in modern immunology. In the 1970s, he uncovered the genetic mechanism that allows the body to generate an extraordinary diversity of antibodies, revealing how immune cells rearrange their DNA to recognize and defend against countless threats.
This groundbreaking work solved a fundamental biological mystery and earned him the 1987 Nobel Prize in Physiology or Medicine.
His discovery fundamentally reshaped immunology by explaining how the immune system can recognize an almost limitless array of foreign targets despite having a finite number of genes. That insight laid the foundation for decades of research into adaptive immunity, deepening our understanding of how immune cells distinguish healthy cells from diseased ones.
Today, those principles continue to underpin advances in cancer immunology and immunotherapy, informing the development of therapies that harness the immune system to recognize and eliminate cancer.
A scientist of remarkable breadth, Dr. Tonegawa later turned his attention to neuroscience, where he pioneered research into the molecular basis of learning and memory at the Massachusetts Institute of Technology (MIT). Throughout his tenured career, he remained steadfast in pushing the boundaries of scientific discovery while mentoring generations of researchers across disciplines.
As a member of CRI’s Scientific Advisory Council, Dr. Tonegawa generously shared his expertise and scientific vision, helping guide the organization’s commitment to supporting innovative research with the potential to transform cancer treatment. His curiosity, rigor, and willingness to challenge conventional thinking exemplified the spirit of discovery that has driven CRI’s mission for more than 70 years.
“The history of cancer immunotherapy rests on a handful of discoveries that fundamentally changed how we think about the immune system. Dr. Tonegawa’s discovery of the genetic mechanism that creates antibody diversity is one of them. His work revealed the remarkable adaptability of the immune system and forever changed how scientists study immunity, disease, and cancer,” said Alicia Zhou, PhD, CEO of CRI. “We were honored to benefit from his wisdom as a member of our Scientific Advisory Council, and his legacy will continue to inspire generations of scientists working to improve the lives of patients.”
Later in life, Dr. Tonegawa was asked how he defined creativity. He laid out three principles that came to mind:
- Be very curious about something
- Have an unfailing urge to address the question you have
- Combine knowledge from at least two different fields
His humble and inspiring reply reflects the grounding principles of open-mindedness and collaboration that make great science possible.
We extend our heartfelt condolences to Dr. Tonegawa’s family, friends, colleagues, and former trainees. His discoveries changed the course of immunology, shaped modern biomedical research, and continue to inspire scientists working to improve the lives of patients with cancer and countless other diseases.
