Tumor Environment Reprograms Immune Cells to Fuel Cancer Growth

Research from the University of Geneva has revealed that tumors can manipulate immune cells, specifically neutrophils, to promote their own growth rather than fight cancer. Published on February 10, 2026, in the journal Cancer Cell, this study identifies how the tumor environment alters neutrophils, leading them to produce a molecule known as CCL3 that enhances tumor progression.

Understanding tumor growth and spread is a central challenge in cancer research. The study, conducted in collaboration with the Ludwig Institute for Cancer Research, highlights the complex interplay between various cell types within the tumor microenvironment. According to Mikaël Pittet, a full professor at the University of Geneva and one of the study’s lead authors, identifying the interactions that drive tumor growth remains difficult.

Pittet noted that this research builds on previous findings from 2023, which linked specific gene expressions in macrophages to disease progression. The current study introduces a new variable involving neutrophils, which are typically the body’s first line of defense against infections.

Neutrophils Transition from Defenders to Tumor Promoters

Neutrophils are abundant immune cells that usually act to protect the body. Yet their presence in cancerous tissues often correlates with adverse outcomes. The researchers found that tumors actively recruit neutrophils and induce significant changes in their behavior. “We discovered that neutrophils recruited by the tumor undergo a reprogramming of their activity,” explained Pittet. “They start producing CCL3, which promotes tumor growth rather than combating it.”

This transformation turns what is normally a protective immune response into one that facilitates cancer proliferation. The implications of this finding are significant, as it suggests that targeting this reprogramming could be a potential therapeutic strategy.

Innovative Approaches to Study Neutrophils

Studying neutrophils poses considerable technical challenges, particularly concerning genetic manipulation. Evangelia Bolli, co-lead author of the study, described how the team used various experimental strategies to control the expression of the CCL3 gene specifically in neutrophils. “We had to innovate to detect neutrophils more accurately,” said Pratyaksha Wirapati, a co-first author and bioinformatics specialist involved in the study.

The researchers developed a novel method to analyze neutrophil activity, which is often overshadowed by their low genetic expression levels. Their analysis confirmed that a common pattern exists across many cancer types: neutrophils produce high levels of CCL3, correlating with pro-tumor activity.

By identifying CCL3 as a crucial factor in tumor growth, the research team has opened a path for understanding cancer evolution more clearly. “We are deciphering the ‘identity card’ of tumors,” Pittet stated, emphasizing the importance of recognizing key variables that dictate disease progression. This knowledge could lead to more personalized and effective cancer treatment strategies in the future.

The study underscores the need for ongoing research into the complex interactions within the tumor microenvironment, as understanding these dynamics could enhance therapeutic approaches and improve patient outcomes.