Pattern of autologous stem cell transplants at a tertiary care government hospital, with emphasis on transplant outcomes with pre-harvest CD34+ level

PURPOSE: Autologous stem cell transplantation (ASCT) is an established therapy for many hematological diseases. This study assessed the pattern of ASCTs at a tertiary care center and associated factors, including pre-harvest CD34+ stem cell levels, leading to improved engraftment outcomes. METHODOLOGY: A retrospective study was conducted in India, between February 2009-August 2020. Patients who underwent ASCT for different hematological malignancies (n=65) were included, and the patients' age, sex, type and stage of disease, pre- and post-harvest CD34+ counts, and time to attain platelet/neutrophil engraftment or febrile neutropenia were analyzed. The post-harvest CD34+ dose was calculated. Pre-conditioning was performed using Granulocyte Colony Stimulating Factor (GCSF)±Plerixafor. Progression-free survival (PFS) was calculated using relapse/death as the endpoint. RESULTS: The median age of the cohort (n=65) was 49 years, with a male preponderance. Multiple myeloma was the most common malignancy (70.8% [46/65]), requiring ASCT. The median time to ASCT was 13 months. All patients had received GCSF, while Plerixafor was used in 17 patients with a pre-harvest CD34+ count of <10 cells/μL. The median pre-harvest CD34+ concentration and post-harvest CD34+ cell dose was 27.54 cells/μL (n=26) and 5.23×10(6) cells/kg body weight (n=65), respectively. The median time to engraftment was 11 and 12 days, for neutrophils and platelets, respectively. One patient did not engraft and was excluded from the analysis. The time required to attain neutrophil engraftment was significantly lower (p=0.02) among freshly harvested stem cells (n=48) than that of cryopreserved products (n=17). Platelet engraftment associated with CD34+ pre- and post-harvest levels was not significant (p=0.06). The time to attain neutropenia and subsequent febrile neutropenia was significantly lower with an adequate post-harvest CD34+ dose (p=0.009). Febrile neutropenia was seen in 83.1% (54/65) patients. The median time for febrile neutropenia was 4 days post-ASCT. Pre- and post-harvest CD34+ concentrations were directly proportional to each other (p<0.001). The median PFS was 112 months (n=65). Survival was better in males (median PFS: 112 months) vs. females (median PFS: 59 months) (p=0.27). Eight patients relapsed, and eight patients had died. CONCLUSION: Although unrelated to age or sex, the post-harvest CD34+ dose was inversely related to febrile neutropenia. As pre- and post-harvest CD34+ levels were directly proportional, pre-harvest CD34+ concentrations may be reliably used to assess engraftment outcomes. Rapid neutrophil engraftment was noted in fresh stem cells with PFS of 112 months, and was better among males, the exact reason being unknown. Thus, a larger number of patients should be followed up to obtain an accurate picture.