Tracking down resistant cancer cells
In multiple myeloma, a cancer of the bone marrow, relapse almost always occurs after treatment. Initially, most patients respond well to therapy. However, as the disease progresses, resistant cancer cells spread in the bone marrow, with fatal consequences for the patients. Scientists at the German Cancer Research Center (DKFZ), Heidelberg University Hospital (UKHD) and the National Center for Tumor Diseases (NCT) in Heidelberg have now used single-cell sequencing to elucidate how myeloma cells with different genetic characteristics change in interaction with the surrounding immune cells in a patient during relapse. The results point to new approaches to counteract relapse.
In the bone marrow, the myeloma cells reprogram the cells of the immune system. In this way, they create an environment in which they can continue to spread.
© DKFZ
Molecular analyses of tumor genetic material typically determine an "average" of tens of thousands of cancer cells. Information on the heterogeneity of the tumor as well as the contribution of healthy cells in the sample is lost. New technologies now make it possible to sequence and quantify all mRNAs at the level of individual cells and also to identify changes in the genetic material from them. This makes it possible to follow exactly how individual subsets of cancer cells with different mutations develop during treatment. This is particularly important for understanding why patients who initially responded well to therapy relapse.
"In our current study, we analyzed the RNA sequences of about half a million individual cells. We were able to see how the composition of different cancer cell clones changes within a patient in multiple myeloma and how individual clones can reprogram the immune cells in their environment," explains Karsten Rippe, who is coordinating the study together with Marc-Steffen Raab as part of the Translational Myeloma Research Program at DKFZ and UKHD. "We can now better identify the molecular changes in individual myeloma cells that indicate emerging resistance" said Marc-Steffen Raab, clinical director of the Heidelberg Myeloma Center. "This provides new approaches to develop targeted drugs or combinations of drugs for patients to counteract relapse."
Next, the scientists want to find out how new immunotherapies affect both myeloma cells and immune cells in the bone marrow, and how single-cell sequencing can be used to better predict the success of these treatments.
The work was technically supported and funded by the NCT Molecular Precision Oncology Program and the Dietmar Hopp Foundation.
Tirier SM, Mallm J-P, Steiger S, Poos AM, Awwad M, Giesen N, Casiraghi N, Susak H, Bauer K, Baumann A, John L, Seckinger A, Hose D, Müller-Tidow C, Goldschmidt H, Stegle O, Hundemer M, Weinhold N, Raab MS & Rippe K (2021) Subclone-specific microenvironmental impact and drug response in refractory multiple myeloma revealed by single cell transcriptomics. Nat Commun, published online 29 November 2021, doi: 10.1038/s41467-021-26951-z.
The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) with its more than 3,000 employees is the largest biomedical research institution in Germany. More than 1,300 scientists at the DKFZ investigate how cancer develops, identify cancer risk factors and search for new strategies to prevent people from developing cancer. They are developing new methods to diagnose tumors more precisely and treat cancer patients more successfully. The DKFZ's Cancer Information Service (KID) provides patients, interested citizens and experts with individual answers to all questions on cancer.
Jointly with partners from the university hospitals, the DKFZ operates the National Center for Tumor Diseases (NCT) in Heidelberg and Dresden, and the Hopp Children's Tumour Center KiTZ in Heidelberg. In the German Consortium for Translational Cancer Research (DKTK), one of the six German Centers for Health Research, the DKFZ maintains translational centers at seven university partner locations. NCT and DKTK sites combine excellent university medicine with the high-profile research of the DKFZ. They contribute to the endeavor of transferring promising approaches from cancer research to the clinic and thus improving the chances of cancer patients.
The DKFZ is 90 percent financed by the Federal Ministry of Education and Research and 10 percent by the state of Baden-Württemberg. The DKFZ is a member of the Helmholtz Association of German Research Centers.
