Bone marrow mononuclear cell count does not predict neutrophil and platelet recovery following autologous bone marrow transplant: Value of the colony-forming unit granulocyte-macrophage (CFU-GM) assay

The common use of the marrow autograft mononuclear cell (MNC) count derives from positive correlative studies following allogeneic transplantation and from earlier conflicting data regarding the value of the bone marrow autograft colony-forming unit granulocytemacrophage (CFU-GM) assay for predicting hematologic recovery after ABMT. We conducted a retrospective analysis at our institution to determine whether autograft CFU- GM levels predict engraftment of neutrophils and platelets after ABMT in heavily pretreated patients with hematologic malignancies. Between 1 January 1993 and 1 March 1995, 58 heavily pretreated patients received only marrow cells as the autograft product. Patients with Hodgkin's disease (n = 25), acute myeloid leukemia (n = 19), and non-Hodgkin's lymphoma (n = 14) underwent intensive therapy with etoposide and melphalan. Unpurged marrow containing a minimum of 1.5 x 10⁸/kg (range: 1.5-4.8) was infused. Median time to an absolute neutrophil count ≤0.5 x 10⁹/L was 21 days (range 10- 270) and median time to a platelet count ≤20 X 10⁹/L independent of transfusions was 44 days (range 13-317). There was no correlation between autograft MNC count and neutrophil or platelet engraftment. However, a correlation between autograft CFU-GM and both platelet and neutrophil recovery was demonstrated with a threshold CFU-GM of 3 x 10⁴/kg; delayed neutrophil recovery was observed in 79% of patients below this threshold compared to only 9% in those with an autograft CFU-GM level of more than 3 x 10⁴/kg (p = 0.0001). Similarly, platelet recovery was delayed in 76% of patients below, and 20% of those above this threshold (p = 0.003). We conclude that marrow autograft CFU-GM is predictive of engraftment of both platelets and neutrophils in heavily pretreated patients after ABMT for hematological malignancies.