Compositions and methods for stabilizing circulating tumor cells

A method for blood sample treatment comprising:

• locating about 50 μl to about 400 μl of a protective agent into a tube, the protective agent including imidazolidinyl urea, EDTA and glycine;
• drawing a blood sample having a first circulating tumor cell concentration into the tube, whereby it contacts the protective agent;
• isolating circulating tumor cells from the contacted blood sample at least 24 hours after the blood draw, the contacted blood sample having a second circulating tumor cell concentration, wherein the second circulating tumor cell concentration is not lower or higher than the first circulating tumor cell concentration by any statistically significant value;
• and
• wherein the concentration of the imidazolidinyl urea after the contacting step is greater than 5 mg/ml;
• wherein the concentration of the glycine after the contacting step is below about 0.03 g/ml;
• wherein the protective agent is present in an amount that is less than about 5% of an overall mixture volume of the protective agent and the drawn blood sample;
• wherein the method is free of any step of refrigerating the contacted blood sample to a temperature below room temperature after it has been contacted with the protective agent composition;
• and
• wherein as a result of metabolic inhibition of the circulating tumor cells in the treated blood sample, apoptotic and necrotic pathways are inhibited and the circulating tumor cells are protected from cell degradation.