Association of CD 34 positive cell dose with engraftment kinetics in autologous peripheral blood stem cell transplant patients of multiple myeloma

Background: Treatment with high-dose chemotherapy and stem cell transplantation has prolonged survival in patients of multiple myeloma (MM). A dose-response relationship between number of CD34+ cells infused and leukocyte and platelet recovery, exists. Patients receiving dose of <2.0 × 10⁶ CD34+ cells/kg have delayed engraftment. The level of optimal cutoff for accelerated engraftment is yet to be validated. Hence, this study was undertaken to study the association of CD 34+ cell dose with engraftment kinetics in patients of MM who underwent autolgous peripheral blood stem cell transplant (PBSCT).

Methods: We retrospectively analyzed 19 patients of MM who underwent PBSCT at our center between December 2016 to December 2018. Complete blood counts were carried out daily after transplantation to record neutrophil and platelet engraftment.

Results: Based on the CD34+ cell dose given : <5 × 10⁶/kg (category 1), 5-10 × 10⁶/kg (category 2), >5 × 10⁶/kg (category 3), the mean (SD) neutrophil engraftment time was 11.3 (0.5) days, 10.6 (0.9) days, and 10.2 (1.3) days respectively. Platelet engraftment time was 12.4 (2.60) days, 10.6 (1.14) days, and 11.2 (1.64) days for category 1, 2, and 3 patients, respectively. Correlation co-efficient between CD 34+cell dose and days for neutrophil and platelet engraftment was found to be -0.24 and -0.20, respectively. Time for neutrophil engraftment was found to be significantly associated with CD34+ cell dose category.

Conclusion: CD 34+ cell dose appears as the strongest predictor of leukocyte and platelet engraftment. CD 34+ cell dose of >5.0 × 10⁶ cells/kg leads to an accelerated neutrophil and platelet engraftment in patients of MM.