To Predict Success of Postapheresis Yield and Post–Autologous Transplant Engraftment Based on Preapheresis Peripheral Blood CD34+ Cell Counts: An Indian Scenario–Based Study
Authors: Devi Pinki , Bhat Ganapathi , Ahuja Harish S. 
Published: September 2021

Introduction The use of hematopoietic stem cells for autologous and allogeneic transplantation has increased in the recent past significantly, due to introduction of newer chemotherapeutic drugs, immunological techniques, and better stem cell technology. Among the bone marrow and peripheral blood stem cells, collection of the latter being more convenient to the patient and associated with faster granulocyte and platelet engraftment has been known as preferred method for mobilization. Peripheral blood stem cells can be extracted from the autologous or allogeneic donor. Mobilization of the stem cells for autologous stem cell transplant is traditionally done using growth factors alone or in combination with chemotherapy, with or without an additional mobilizing agent. A significant number of hematological malignancy patients are poor mobilizers, (i.e., they are unable to achieve the minimal target cell dose during their first round of mobilization).Therefore, a prediction for a successful stem cell mobilization ideally should be made before initiating any apheresis procedure to spare those with a low rate of success from the risks associated with apheresis procedure. Preapheresis CD34 cell count can predict postapheresis yield and hence, can help to reduce the collection sessions. Reduction of apheresis sessions decreases the discomfort, inconvenience, time, and monetary expenses.

Objectives This study was aimed to analyze preapheresis and postapheresis CD34+ cell counts.

Materials and Methods Patients of any age and gender with diagnosis of hematological malignancies admitted for autologous stem cell transplantation for hematological malignancies (including Hodgkin lymphoma, non-Hodgkin lymphoma, and multiple myeloma) and germ cell tumors in our institute from July 2008 to July 2016 were included in the study. The post-GCSF CBC, preapheresis CBC, CD34+ cell counts, and postapheresis CBC, CD34+ cell counts, mononuclear cell counts to predict the outcome of amount of yield. The effect on engraftment will be measured according to the defining criteria of achieving a sustained peripheral blood neutrophil count of >500 × 106/L (Wolff 2002) and a platelet count of more than >20 × 109/L (Teltschik et al. 2016) independent of platelet transfusion for at least 7 days. Collection of stem cells was done using apheresis machine (COBE SPECTRA). Complete peripheral blood counts using automated analyzers. Peripheral blood CD34 + cell counts and postapheresis CD34+ cell count using BD FACS CANTO II flow cytometer. To calculate postapheresis yield, the related CD34 count measured by flow cytometer was multiplied by the apheresis product volume and divided by the recipient’s body weight (kg). Number of CD34+ cells collected = (CD34 cell concentration in final product) × (final product volume).

Results A total of 100 patients who underwent a total of 320 apheresis sessions were included in the study. There were 78 males and 22 females. We also found a significant correlation between preapheresis CD34 + cell count and postapheresis CD34 percentage on days 1, 2, and 3 of the apheresis sessions. In our study, to obtain more than 1.31 × 106 cells (median = 1.04, range: 0.15–4.70), an absolute count of pre apheresis CD34 + cells ≥14 cells would be necessary. A target of CD34 + cells ≥ 2 × 106/kg was obtained in majority of patients if a concentration of ≥25 CD34 + cells was present in postapheresis collection.

Conclusion Compiling our results with the previous published data, we conclude that there is a strong correlation between preapheresis absolute CD34 + cell counts and postapheresis CD34 + cell count. Our study also suggests that the minimum absolute cell count of >10 cells/μL is required, to achieve a target of >2–5 × 106 cells for postapheresis yield.