How The Immune System Fights Cancer

A woman in a lab with a bunch of colored crystals.

The evolution of immuno-oncology (IO) represents a major advancement in cancer therapy over the past decade. However, across all different tumors around 70 percent of patients who receive IO treatments do not benefit from them. At Bayer, we are advancing a portfolio of various IO projects, with a primary focus on next-generation targets, as well as looking into different combination approaches with targeted therapies order to optimize cancer treatment.

The promise of immuno-oncology

The immune system is your body’s defense mechanism: it usually protects the body from the harmful effects of pathogens or abnormal cells, including cancer cells. In some cases, cancer cells can escape detection and elimination and form tumors. If a patient develops a tumor, this can weaken their immune response. But, did you know that the body’s own immune system can actually be mobilized to fight cancer?


What is immuno-oncology?

Cancer cells arise every day – typically as a result of a genetic predisposition or environmental influences – but are usually eliminated by the immune system. However, in some cases, the malignant cells can disguise themselves, evade the immune response and develop into tumors. Immuno-oncology is an innovative area of cancer research that looks into how the immune system can be supported to fight cancer from within, by re-activating the body’s immune response against the tumor. Immuno-oncology drugs seek to uncloak cancer cells that have evaded the body’s immune response so that the immune system can attack and destroy them.

A man with glasses stands in front of a glass wall.
Immuno-oncology has fundamentally changed the way cancer is being treated today. Activating the power of the immune system has shown to be successful in treating a growing number of cancer indications.
Bertolt Kreft
Head of Immuno-oncology Research at Bayer
How does immuno-oncology work?

Any productive immune response in the body is followed by a suppressive counter response which is characterized by the expression of so-called “immune checkpoint” receptors or by the attraction of regulatory immune cells. This counter response prevents excessive inflammation and tissue damage once an infection has been cleared from the body. However, tumors can harness this mechanism to protect themselves against destruction by the immune system.


Scientists have identified a first generation of immune-checkpoint inhibitors (ICIs) that have been approved to treat certain types of cancer. These ICIs target immune checkpoints and reactivate the immune system to find and destroy tumor cells.

However, the fact that only 30 percent of patients have responded to the first generation of ICIs indicates significant potential for future treatment strategies in this field. We collaborate with scientists from the German Cancer Research Center (DKFZ) and others, to improve the anti-tumor response and find new treatment options for patients.


A man in a white lab coat poses for a photo.
It is a great experience to see the interaction of bright and dedicated expert scientists from academia and industry in the Bayer-DKFZ alliance. It has allowed us to translate basic biology findings into treatment modalities, which are now moving toward clinical application in an astonishingly short period of time.
Professor Michael Platten
Group Leader in Neuroimmunology and Brain Tumor Immunology at the DKFZ

Slideshow: How the body fights cancer: the cancer immunity cycle1

Find out how the immune system fights cancer cells and where Bayer and the DKFZ are stepping in to support the immunological response.

However, tumors evolve ways to block each step of the cancer immunity cycle. The goal of immuno-oncology therapies is to identify immunosuppressive mechanisms and interfere with them to re-enable the immune system to fight cancer.


Our research at Bayer focuses on supporting the immune system at various points in the immunity cycle. For example, we are not only investigating how to improve T-cell activity within the tumor, but also how to boost the priming of T-cells in the lymph nodes as well as improve their infiltration into the tumor.




1 Chen DS, Mellman I. Oncology meets immunology: the cancer-immunity cycle. Immunity. 2013;39:1-10. PMID: 23890059