Ideal or actual body weight to calculate CD34+ cell doses for allogeneic hematopoietic stem cell transplantation?

Ideal body weight is useful for predicting neutrophil engraftment and platelet recovery for overweight and obese recipients in single-unit cord blood transplantation

BACKGROUND

Since cord blood (CB) units are usually selected based on the cell dose /kg, overweight (25 kg/m² ≤ body mass index (BMI) < 30 kg/m²) and obese (30 kg/m² ≤ BMI) recipients tend to have difficulty in getting appropriate CB units. In general, actual body weight (ABW) is used for CB unit selection. However, ideal body weight (IBW) has been reported to be more closely correlated with successful engraftment after autologous, allogeneic bone marrow, and peripheral blood stem cell transplantation than ABW.

OBJECTIVES

We conducted this analysis to clarify the threshold of CD34⁺ cell doses based on ideal body weight (CD34^IBW) and to compare the outcomes among the groups stratified by the threshold according to actual body weight (CD34^ABW) and CD34^IBW for overweight and obese recipients in cord blood transplantation (CBT).

STUDY DESIGN

We retrospectively analyzed 650 overweight and obese recipients who received single-unit CBT. To focus on the recipients who received a low CD34⁺ cell dose /kg, those who received 1.5×10⁵ CD34⁺ cells /ABW or more were excluded. Using a cut-off of 0.8×10⁵ CD34⁺ cells/kg, we compared the outcomes in 3 groups with low CD34^ABW and low CD34^IBW (CD34^Low/Low), low CD34^ABW but high CD34^IBW (CD34^Low/High), and high CD34^ABW and high CD34^IBW (CD34^High/High).

RESULTS

Hematopoietic recoveries were significantly delayed in the CD34^Low/Low group compared with those in the CD34^Low/High group (hazard ratio (HR) 0.67 for neutrophil, P < 0.001; HR 0.72 for platelet, P = 0.014), while those were comparable in the CD34^Low/High and CD34^High/High groups (HR 1.22 for neutrophil, P = 0.16; HR 1.29 for platelet, P = 0.088). Moreover, the CD34^Low/High group demonstrated longer overall survival than the CD34^Low/Low group (HR 1.48, P = 0.011) and comparable survival to the CD34^High/High group (HR 0.93, P = 0.68).

CONCLUSIONS

This finding may address the lack of availability of CB units for some overweight and obese recipients for whom suitable donors are unavailable. Further investigations are warranted to evaluate the appropriateness of ABW and IBW.

Allogeneic hematopoietic cell transplantation; the current renaissance

Allogeneic hematopoietic cell transplantation (HCT) provides the best chance for cure for many patients with malignant and nonmalignant hematologic disorders. Recent advances in selecting candidates and determining risk, procedure safety, utilization in older patients, use of alternative donors, and new or novel application of anti-cancer, immunosuppressive and antimicrobial agents have improved outcomes and expanded the role of HCT in hematologic disorders. Relapse remains the predominant cause of failure but enlightened use of new targeted and immunotherapeutic agents in combination with HCT promises to reduce relapse and further improve HCT outcomes.

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 x 10(6)/kg CD34 + cells was not significantly different from those receiving <6. The outcome of those receiving 6-8 x 10(6)/kg CD34 + cells was significantly better than the rest. This superiority was confirmed in multivariable analysis. Among patients receiving <or=8 x 10(6)/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 x 10(6) per kg ideal body weight to optimize outcome. The possible adverse effect of higher cell doses (>8) needs further confirmation.

Ideal body weight correlates better with engraftment after PBSC autograft than actual body weight, but is under-estimated in myeloma patients possibly due to disease-related height loss

Stem cell dose is important in determining rate of engraftment following autograft. We show closer correlation with haematopoietic reconstitution when the CD34+ cell dose is calculated using ideal (IBW) rather than actual (ABW) body weight in 218 patients receiving peripheral blood stem cell (PBSC) autograft for haematological malignancy. ABW was 21% greater than IBW thus the median CD34+ dose of 5.0 x 10(6)/kg (ABW) rose to 6.1 x 10(6)/kg when calculated by IBW. Neutrophils reached 0.5 x 10(9)/l in 11 days (range 8-21), while platelets reached 20 x 10(9)/l unsupported in 12 days (range 7-38). For both neutrophil and platelet engraftment, a greater inverse correlation was seen when IBW was used to calculate stem cell dose (r2=0.082 vs r2=0.104 for neutrophils and r2=0.085 vs r2=0.135 for platelets). Those non-myeloma patients who failed to achieve a CD34+ dose of 4 x 10(6) cells/kg by ABW but did so by IBW achieved neutrophil and platelet engraftment not significantly different from those who achieved that stem cell dose by both methods. This was not confirmed in patients treated for myeloma, possibly owing to inaccurate IBW in patients with skeletal height loss. We confirm that calculation of CD34+ cell dose by IBW safely predicts engraftment for patients with haematological malignancies other than myeloma undergoing PBSC autograft.

How to calculate the quantity of CD34+ cells infused? A single center cohort study based on actual, ideal or adjusted ideal body weight

Transplant physicians are generally using the recipient's actual body weight (ABW) for the calculation of the content of CD34+ cells in the harvest material in hematopoietic stem cell transplantation (HSCT). As a reference center performing both the stem cell collection and HSCTs, we aimed to evaluate whether there were any differences for neutrophil recovery by calculating the CD34+ cell content in the graft according to actual, ideal (IBW) or adjusted IBW (AIBW) of the recipients in both autologous (n=148) and allogeneic stem cell collection setting (n=234). We observed a negative correlation between the neutrophil recovery and the cell doses infused as to each of these BWs in the allo-HSCT group, but not in the auto-HSCT group. This negative correlation was stronger for IBW and AIBW rather than for ABW in allo-HSCT group. In addition, calculations for both IBW and AIBW in autologous and allogeneic transplants revealed a significant difference in comparison to ABW for different cut-off values of infused CD34+ cells. Consequently, we suggested that both IBW and AIBW based calculations of CD34+ cells infused are better predictors of neutrophil recovery in comparison to ABW in allo-HSCT. We were not able to show this impact in autologous transplants.

Does younger donor age affect the outcome of reduced-intensity allogeneic hematopoietic stem cell transplantation for hematologic malignancies beneficially?

Sixty three patients aged 27-66 years (median 52) were allografted from HLA-matched sibling (n=47), 10 of 10 allele-matched unrelated (n=19), or one-antigen/allele-mismatched (n=7) donors aged 24-69 years (median 46) after a conditioning regimen comprising 100 mg/m(2) melphalan. Cyclophosphamide (50 mg/kg) was also administered to patients who had not been autografted previously. Cyclosporine or tacrolimus, and mycophenolate mofetil were administered to prevent graft-versus-host disease (GVHD). The 2-year cumulative incidences of relapse and TRM were 55 and 24% respectively, and 2-year probabilities of overall survival (OS) and disease-free survival (DFS) were 36 and 21%, respectively. Poor performance status, donor age >45 years and elevated lactate dehydrogenase (LDH) increased the risk of treatment-related mortality (TRM), refractory disease and donor age >45 years increased the risk of relapse, and OS and DFS were adversely influenced by refractory disease, poor performance status, increased LDH, and donor age >45 years. Our data suggest that younger donor age is associated with better outcome after sub-myeloablative allogeneic hematopoietic stem cell transplantation (HSCT) for hematologic malignancies due to lower TRM and relapse. This finding raises the question of whether a young 10-allele-matched unrelated donor is superior to an older matched sibling donor in patients where the clinical situation permits a choice between such donors.

Ideal rather than actual body weight should be used to calculate cell dose in allogeneic hematopoietic stem cell transplantation

Whether the CD34+ and CD3+ cell doses in allogeneic HSCT should be estimated using actual (ABW) or ideal (IBW) body weight has never been definitively determined. We have shown that CD34+ cell doses based upon IBW are better predictive of engraftment after autologous and allogeneic HSCT. Sixty-three patients undergoing reduced-intensity HSCT after a uniform preparative regimen were evaluated to determine the effect of cell dose. ABW and IBW were 45-147 kg (median 79) and 52-85 kg (median 67) respectively. The ABW-IBW difference was -24% to +133% (median +16%); nine patients were >5% underweight and 41 were >5% overweight. The CD34+ cell dose (10(6)/kg) was 1.4-11.8 (median 5) by IBW and 1.2-9.3 (median 4.5) by ABW. The CD3+ cell dose (10(8)/kg) was 0.9-14.9 (median 3) by IBW and 0.7-19.7 (median 2.7) by ABW. While CD34+ and CD3+ cell doses based upon IBW were found to affect transplant-related mortality, and disease-free and overall survival significantly, those based on ABW were either not predictive of outcome or the differences were of borderline significance. We suggest using IBW rather than ABW to calculate cell doses for HSCT; for statistical analyses and for clinical practice if a specific cell dose is being targeted.