In most cases, no. In fact, most individuals we serve are being treated with a current standard of care therapy while we develop their personalized O-PDX models for testing. An exception is if you had radiation treatments, within 10 weeks, at the site from which a fresh tissue biopsy needs to be taken. Radiated tumor tissue will rarely engraft in mice.1
1 Russell, T. A., Eckardt, M. A., Murakami, T., Elliott, I. A., Kawaguchi, K., Kiyuna, T., Igarashi, K., Li, Y., Crompton, J. G., Graham, D. S., Dry, S. M., Bernthal, N., Yanagawa, J., Kalbasi, A., Federman, N., Chmielowski, B., Singh, A. S., Hoffman, R. M., & Eilber, F. C. (2017). Clinical Factors That Affect the Establishment of Soft Tissue Sarcoma Patient-Derived Orthotopic Xenografts: A University of California, Los Angeles, Sarcoma Program Prospective Clinical Trial. JCO Precision Oncology, 2017.