Ex-vivo assessment of drug response on breast cancer primary tissue with preserved microenvironments

ABSTRACT

Interaction between cancerous, non-transformed cells, and non-cellular components within the tumor microenvironment plays a key role in response to treatment. However, short-term culture or xenotransplantation of cancer specimens in immunodeficient animals results in dramatic modifications of the tumor microenvironment, thus preventing reliable assessment of compounds or biologicals of potential therapeutic relevance.

We used a perfusion-based bioreactor developed for tissue engineering purposes to successfully maintain the tumor microenvironment of freshly excised breast cancer tissue obtained from 27 breast cancer patients and used this platform to test the therapeutic effect of antiestrogens as well as checkpoint-inhibitors on the cancer cells.

Viability and functions of tumor and immune cells could be maintained for over 2 weeks in perfused bioreactors. Next generation sequencing authenticated cultured tissue specimens as closely matching the original clinical samples. Anti-estrogen treatment of cultured estrogen receptor positive breast cancer tissue as well as administration of pertuzumab to a Her2 positive breast cancer both had an anti-proliferative effect. Treatment with anti-programmed-death-Ligand (PD-L)-1 and anti-cytotoxic T lymphocyte-associated protein (CTLA)-4 antibodies lead to immune activation, evidenced by increased lymphocyte proliferation, increased expression of IFNγ, and decreased expression of IL10, accompanied by a massive cancer cell death in ex vivo triple negative breast cancer specimens.

In the era of personalized medicine, the ex vivo culture of breast cancer tissue represents a promising approach for the pre-clinical evaluation of conventional and immune-mediated treatments and provides a platform for testing of innovative treatments.

KEYWORDS:

• Breast cancer
• CTLA-4
• immune checkpoint inhibitors
• PD-L1
• tissue engineering
• tumor microenvironment

Disclosure of potential conflicts of interest

Manuele G. Muraro and Giulio C. Spagnoli are Cellec Biotek AG share-holders.

Acknowledgments

We thank Christian Hirt for his help in setting up the method of U-CUP culture. We further thank David Blattner for his help with the specimen handling. We also thank Michèle Baumann for the embedding, processing and staining of the slides, Petra Hirschmann for the IHC staining, and the collaboration of Elisabeth Adams for her support with the Pertuzumab experiments. This work was supported by the Holcim Foundation for the Advancement of Scientific Research, the Claudia von Schilling Foundation for Breast Cancer Research, the Freiwillge Akademische Gesellschaft Basel and the Huggenberger-Bischoff Foundation.

Author contributions

M.G.M. set up, planned, and performed all the bioreactor experiments, provided technical support for this technology, contributed to the figures, and wrote part of the manuscript. S.M. did the histologic analyses, provided the histological images for the figures, and wrote part of the manuscript. S.D.S. planned, sponsored, coordinated, and supervised the experiments, provided breast cancer samples, and wrote part of the manuscript. A.T. did the statistical analysis, wrote the statistics part of the manuscript, and critically revised the manuscript. V.M. performed PCR, and ELISA analysis, wrote part of the manuscript, and critically revised it. L.Q. performed NGS, wrote part of the manuscript, and critically revised it. W.P.W. provided breast cancer samples and critically revised the manuscript. G.I. had previously helped to establish the culture system. G.S. contributed to the planning of the experiments and critically revised the manuscript.