J. Krishnamurthy

Optimizing the CD34 + cell dose for reduced-intensity allogeneic hematopoietic stem cell transplantation

Low CD34 + cell doses increase allograft-related mortality and very high doses increase the risk of graft-versus-host disease. The optimum CD34 + cell dose remains undefined. The effect of the CD34 + cell dose based on ideal weight was analyzed in 130 patients with hematologic malignancies undergoing reduced-intensity allogeneic blood cell transplantation in the context of factors known to affect the outcome: chemosensitivity, donor age, lactate dehydrogenase (LDH), human leukocyte antigen (HLA) match, performance status, and platelet count. The survival of patients receiving >8 × 106/kg CD34 + cells was not significantly different from those receiving <6. The outcome of those receiving 6–8 × 106/kg CD34 + cells was significantly better than the rest. This superiority was confirmed in multivariable analysis. Among patients receiving ≤8 × 106/kg CD34 + cells, an increasing number of infused cells was associated with higher overall survival in a continuous fashion (Risk ratio (RR) 0.8759; p = 0.045). Cell dose based on actual weight did not correlate with survival. The number of CD34 + cells infused, a potentially modifiable factor, affects survival after reduced-intensity allogeneic transplantation. We recommend a CD34 + cell dose of 6–8 × 106 per kg ideal body weight to optimize outcome. The possible adverse effect of higher cell doses (>8) needs further confirmation.

Actual or ideal body weight to calculate CD34+ cell dose in patients undergoing autologous hematopoietic SCT for myeloma?

CD34+ cell dose calculations are usually based on actual body weight (ABW). We have shown that ideal body weight (IBW) may provide a better basis for this in a small population of patients with hematologic malignancies. This was studied further in 514 myeloma autografts. The CD34+ cell doses (106/kg) by IBW and ABW were 1.37–39.36 (median 6.03) and 1.15–29.67 (median 4.84), respectively. IBW-based cell doses correlated slightly better with engraftment than ABW-based doses (higher r2): 0.5 × 109/l neutrophils 0.83 versus 0.82, 1.0 × 109/l neutrophils 0.78 versus 0.77, 20 × 109/l platelets 0.54 versus 0.53 and 50 × 109/l platelets 0.57 versus 0.55. When outliers (hematologic recovery in <8 or >16 days) were excluded, the findings were similar: 0.5 × 109/l neutrophils 0.85 versus 0.84, 1.0 × 109/l neutrophils 0.85 versus 0.84, 20 × 109/l platelets 0.86 versus 0.85 and 50 × 109/l platelets 0.85 versus 0.84. CD34+ cell doses based on IBW as well as ABW significantly affected engraftment when analyzed separately as continuous variables. However, when analyzed together, only the dose based on IBW retained significance. We conclude that calculation of CD34+ cell numbers for autotransplantation should be based on IBW.