Fighting Cancer

Dr. Rafael Carretero is researcher at the German Cancer Research Center (DKFZ) in Heidelberg. The battle against cancer has been the common thread through his life.


Oncology research at Bayer is committed to improving the lives of cancer patients. Bayer’s researchers are working together with external partners to develop new therapeutic approaches to this disease.

The moment my best friend was told his mother had died is one I’ll never forget. We were at school together at the time,” remembers Dr. Rafael Carretero. Rafael and Francisco were like brothers. They lived close to each other in the same neighborhood in Granada, Spain, played soccer in the street and spent the summers together with their parents, either hiking in the Sierra Nevada or on the beach at La Herradura. But then Rafael experienced how his best friend’s warm-hearted and cheerful mother suffered the side effects of chemotherapy and radiation therapy before dying – much too young – of breast cancer. “That hit me really hard and was one of the reasons why I decided to devote my life to fighting cancer – so that other people would be spared this fate,” says the Bayer researcher.

Corinna Groß

We develop therapies that enable the patient’s body to detect cancer cells and then defeat them itself.

Carretero is now 34, a molecular biologist and scientific manager of a laboratory run jointly by Bayer and the German Cancer Research Center (DKFZ). Its employees on the sixth floor of the DKFZ’s state-of-the-art building in Heidelberg, Germany, are conducting research to determine how the body’s own immune system can be reactivated to combat tumor cells. This approach was also the subject of Carretero’s PhD at the Hospital Universitario Virgen de las Nieves in Granada. The battle against cancer has been the common thread through his life. “We want to develop therapies that enable the patient’s body to detect cancer cells and then fight them itself without harming healthy cells at the same time,” he explains.

What’s special about the laboratory in Heidelberg is that scientists from both Bayer and the DKFZ work side by side. “This allows us to pick up on novel research findings as early as possible so that they can be channeled into drug development,” explains Dr. Ruth Wellenreuther, alliance manager at the DKFZ. “Research issues have become so complex that no one scientist alone is able to resolve them. Our scientists identify potential new drug targets, and Bayer has extensive libraries of substances and antibodies. The two parties’ respective expertises complement each other ideally, which enables us to reach our objective more quickly.”

Here is a video of two of Bayer's Heidelberg-based cancer researchers.

The joint laboratory is one aspect of a partnership that has been in existence since 2009. Wellenreuther was involved in developing the framework for the collaboration. “This is an alliance between equals. We clarified all the structural and legal issues right at the beginning, so when we identify a new target we can move straight on to searching for suitable active ingredients.” The partnership has already been successful: the first active ingredient to treat brain tumors and leukemia has been undergoing clinical testing in patients for several months now. The substance recognizes proteins that are found only in cancer cells in a subset of patients, an approach that could enable the development of effective, patient-specific therapies.

“We are working to develop innovative treatments for patients with serious diseases such as cancer in order to extend their lives and improve their quality of life,” says Professor Andreas Busch, member of the Executive Committee of Bayer’s Pharmaceuticals Division and head of Drug Discovery. “Our particular strength at Bayer is that we have strong expertise in identifying active ingredients and taking them through all phases of clinical development up to and including drug approval, for the benefit of the patients.”

In the battle against cancer, Bayer is pursuing three main approaches: blocking signaling pathways that lead to uncontrolled cell division; selectively docking molecules onto cancer cells to trigger their targeted destruction; and reactivating the immune system to eliminate cancer cells itself. This latter approach is the focus of the research by Carretero and his colleagues. “Our understanding of cancer is constantly improving, but there are still plenty of unanswered questions,” says Carretero, before turning his attention to the next test findings from the laboratory. “Our goal is to make cancer curable or be able to transform it into a chronic disease by providing therapeutics that keep tumor cells in check.”

Areas of Oncology Research at Bayer

Antibody-drug conjugates
Certain proteins occur more frequently on the surface of cancer cells than in healthy cells. Bayer researchers are developing molecules called antibody-drug conjugates which recognize these proteins. Like a Trojan horse, they dock onto the cancer cells and destroy them with a cell toxin. Antibody-thorium conjugates work in a similar way and transport radioactive thorium-227 to the cancer cells. The resulting energy-rich alpha particles destroy the cancer cells. By using different antibodies, conjugates can be developed for various tumor types.

Blocking oncogenic signaling pathways in specific tumor types
The multiplication of cancer cells is to be halted by intervening in their key molecular processes. One approach aims to block the signaling pathways which prevent cancer cell death and often result in mutations, while another approach seeks to exploit the differences in the metabolic activity of tumor cells. A third approach is investigating cancer stem cells that may result in the development of resistance mechanisms and the failure of chemotherapy and radiation therapy. And a further approach is focused on the epigenetic changes which play a role in malignant cancers. Bayer scientists are working to understand these processes better so they can reverse harmful modifications in diseased cells.

Every day, cancer cells are formed in the human body because of a genetic predisposition or as a result of exposure to cigarette smoke, UV radiation or other environmental influences. They are usually eliminated by the immune system’s cells. In certain cases, however, they can evade the immune response and become a harmful tumor. Bayer researchers are working mainly in collaboration with scientists from the DKFZ on approaches leading to a reactivation of the immune system to eliminate the tumor cells without affecting healthy nontumoral cells. The immune system’s memory function may result in long-term therapeutic success.