New Antibody Target Discovered in Tumors
Researchers have identified a potential new target for cancer treatments on the surface of tumor cells. A protein long known for its role in cancer development, SRC, has been found in an unexpected location, potentially allowing for therapies that directly attack cancer cells.
SRC: A Cancer-Causing Enzyme with a Hidden Location
For over 50 years, scientists have understood the role of the SRC enzyme in cancer development. Previously, it was believed that SRC functioned exclusively inside cells, signaling tumor growth while remaining hidden from the immune system. Though, recent research from the University of California, San Francisco (UCSF) has revealed that the SRC enzyme also appears on the surface of tumor cells in bladder, colorectal, breast, and pancreatic cancers, and likely other tumor types as well. UCSF News
How SRC Reaches the Cell Surface
The researchers discovered that the appearance of SRC on the cell surface is linked to how cancer cells manage waste products. Rapidly dividing cancer cells produce a significant amount of cellular debris. While healthy cells efficiently break down and reuse these residues, tumors often overwhelm their recycling systems. This leads to the expulsion of cellular waste, including the SRC enzyme, onto the cell surface, making it visible to potential therapies like antibodies. Science
Antibody Therapies Show Promise in Mice
Researchers targeted the SRC enzyme with antibodies, some carrying radioactive payloads and others designed to attract immune cells. In experiments conducted on mice, these approaches successfully destroyed cancer cells and reduced tumor size. UCSF News
Potential Impact on Cancer Treatment
According to the researchers, this new therapeutic target could be relevant to up to half of all tumors. “No one thought to look for it on the outside,” said Jim Wells, PhD, professor of Pharmaceutical Chemistry at UCSF and senior author of the study. “Our discovery enables us to test proven immunotherapies on this new tumor target.” UCSF News
The History of SRC in Cancer Research
The SRC gene was first identified as an oncogene – a gene capable of causing cancer – in the 1970s by UCSF researchers J. Michael Bishop and Harold Varmus. This discovery laid the foundation for modern cancer genetics and earned them the Nobel Prize in Medicine in 1989. Since then, efforts to block the SRC enzyme with drugs have been limited, as these drugs affected both cancer and healthy cells. National Today
Understanding SRC’s Journey to the Cell Surface
Researchers tracked the protein in cancer cells grown in the lab and found that SRC is involved in the cellular waste disposal system. Normally, cells sequester debris in vesicles for degradation and reuse. However, in rapidly dividing cancer cells, this system becomes overloaded, leading to the release of vesicles and their contents, including SRC, to the cell surface. Science
Specificity and Future Directions
The researchers identified the SRC enzyme on the surface of bladder cancer cells taken from patients treated at UCSF, but not in healthy bladder tissue or immune cells, suggesting it could be a specific target for antibody-based therapies. UCSF has licensed the antibodies and related molecules to Inversion Therapeutics for further development. National Today
“We have gone through all the steps from discovery to development of two preclinical therapies targeting the SRC enzyme, and the results have been positive,” said Jim Wells. “It’s a remarkably encouraging result.” National Today
The study was published in the journal Science on March 12, 2026. Science