SRC enzyme: a new target for anticancer antibodies

By Elodie Vaz | Published on March 19, 2026 | 3 min read


For over half a century, the oncogenic enzyme SRC has held a central place in cancer research. Identified in the 1970s as the first oncogene by J. Michael Bishop and Harold Varmus—a discovery awarded the Nobel Prize in 1989—this finding profoundly transformed the genetic understanding of cancer. SRC encodes an enzyme involved in intracellular signaling pathways that promote tumor proliferation.  

Until recently, researchers believed that this protein remained confined within cancer cells, making it difficult to access using immunotherapeutic approaches.  

A study conducted at the University of California, San Francisco (UCSF), and published on March 12 in Science, challenges this paradigm. The researchers show that SRC can appear on the surface of many tumor cells, opening the way to a new targeted therapeutic strategy.  

Identifying an antibody-accessible target  

The team led by Jim Wells aimed to determine whether certain proteins considered intracellular could, under specific conditions, become accessible to antibody-based drugs. “No one had thought to look for it outside,” the researcher explained in a press release. “Our discovery allows us to test proven immunotherapies on this new tumor target.”  

The scientists focused in particular on rapidly dividing tumor cells, known to produce large amounts of molecular waste.  

Exploring SRC intracellular trafficking  

To understand how SRC could reach the cell surface, the researchers tracked the protein in cancer cells grown in vitro.  

In healthy cells, waste is typically stored in vesicles and then recycled by degradation systems. However, in fast-growing tumors, these mechanisms become saturated. Vesicles filled with waste then fuse with the plasma membrane and expel their contents outside the cell.  

Observations revealed that SRC can be carried along in this elimination process. “We found that SRC was projected onto the outer membrane, where it remained exposed like a red flag,” explained Corleone Delaveris, first author of the study.  

A target present across many tumors  

Analyses of human tumor samples confirmed the presence of SRC on the surface of bladder cancer cells, while it was absent in healthy bladder tissue and immune cells. This specificity suggests it could be a relevant target for directing therapeutic antibodies toward tumor cells.

The researchers then tested several preclinical approaches. In collaboration with UCSF radiologist Michael Evans, the team developed radioactive antibodies targeting SRC and evaluated them in mice bearing human tumors. The antibodies accumulated in cancer cells and contributed to reducing tumor size.  

Other antibodies were also designed to recruit the immune system and promote tumor cell destruction. According to the researchers, this target could be relevant in nearly half of tumors, including breast, colon, pancreatic, and bladder cancers.  

Toward new immunotherapy strategies  

These results suggest that the accumulation of molecular waste in tumors can expose proteins on their surface that are normally invisible to treatments. Exploiting these “waste products” could therefore provide a new reservoir of therapeutic targets.  

UCSF has already licensed these antibodies to the company Inversion Therapeutics to explore their clinical development. “We went from discovery to developing two preclinical therapies targeting SRC, and they worked,” said Jim Wells. “It’s really exciting.”  

In the longer term, this approach could encourage researchers to revisit other proteins considered strictly intracellular. If these “molecular waste” components are frequently exposed on the surface of cancer cells, they could constitute a new generation of targets for anticancer immunotherapies.   

Read next: Colorectal cancer on the rise

About the Author – Elodie Vaz
Health journalist, CFPJ graduate (2023).
Élodie explores the marks diseases leave on bodies and, more broadly, on human life. A registered nurse since 2010, she spent twelve years at patients’ bedsides before exchanging her stethoscope for a notebook. She now investigates the links between environment and health, convinced that the vitality of life cannot be reduced to that of humans alone.