The use of the Robinson in vitro agar culture assay in adult acute leukemia.

Previous in vitro classification of adult acute leukemia incorporating morphology has been complex and difficult to understand. We have devised a simplified classification based solely on leukemic proliferation in vitro. Forty-four patients with adult acute leukemia previously untreated were included in this study and received identical chemotherapy. Three in vitro groups were recognized. The complete remission rate (CR) was 77% in the 13 patients with no leukemic growth in vitro (Group 1), 81% in 16 patients with leukemic cell growth but aggregated of 20 cells or less (Group 2) and only 27% in the 15 patients with aggregates of greater than 20 (Group 3). There was a highly significant difference in complete remission rates between Group 3 and the other 2 groups (p less than 0.01). Linear logistic regression analysis demonstrated the independence of the in vitro growth from other prognostic variables. The cause of death in failures suggested that this system detects resistance to the chemotherapy. Similar multifactorial analysis including in vitro agar culture may help to predict for chemotherapy response in preleukemia and leukemia with a low blast cell infiltrate when cytotoxic therapy is clinically indicated.