Phase I: New CTC test is developed (and refined) in a laboratory, specificity and sensitivity shown, first clinical data on cancer patients, first publication(s). |
Phase II: New CTC test compared with existing CTC test (criterion standard, e.g., CellSearch) and “superior” findings demonstrated with regard to clinical relevance in a limited study. |
Phase III: New CTC test is disseminated to other CTC-specialized laboratories, and results of the initial studies are reproduced (e.g., specificity, sensitivity, reproducibility in blinded ring experiments). |
Phase IV: New CTC test is implemented in large-scale clinical trial(s) with defined endpoints (e.g., progression-free or overall survival) side-by-side with most established CTC test for the particular cohort of patients and stage and treatment. Circulating tumor cell testing in specialized laboratories. |