Can doses of post-transplantation cyclophosphamide in haploidentical stem cell allografts be reduced?

Figures & data

Figure 1. Scheme of the ‘Mexican Method’ to conduct haploidentical hematopoietic stem cell transplants on an outpatient basis. Cy = cyclophosphamide; pre-transplant Cy: 500 mg/m²; post-transplant Cy: either 25 or 50 mg/Kg. Flu = fludarabine, 25 mg/m². Tac = tacrolimus.

Table 1. Salient features of the two groups of patients given a haploidentical stem cell transplantation.

PTCy, mg/Kg days 3 and 4	50	25	p
Number	21	10
Female	11	4
Male	10	6	0.79^a
Median age	30	17	0.29^b
Acute leukemia	57%	70%	0.49^a
Outpatient	71%	60%	0.97^a
Cardiac toxicity	0%	0%
CRS	48%	20%	0.06^a
Days to > 0.5 × 10e + 9/L neutrophils	15.5	16	0.52^b
Days to > 20 × 10e + 9/L platelets	4.3	0	0.43^b
Months to full chimerism	4	6	0.62^b
Acute GVHD, II-IV	9.50%	12.50%	0.81^a
Chronic GVHD	9.50%	12.50%	0.81^a
Median OS	5.73 mo	6.46	0.42^c
Median RFS	5.13 mo	2.13 mo	0.58^c
40 mo RFS	19.40%	46.70%	0.58^c
40 mo OS	19.80%	53%	0.28^c
Median follow up (months)	4.53	4.26	0.8^b

Note: The Kolmogorov-Smirnov test was used to evaluate the normality of the distribution of the data to be analyzed. Most of the parameters in our study do not conform to a normal distribution, so Mann–Whitney U test was used to evaluate between-group differences. Chi square statistic was used to test for categorical data. PTCy: post-transplant cyclophosphamide; CRS: cytokine release syndrome; GVHD: graft versus host disease; OS: overall survival; RFS: relapse free survival.

^a p value obtained by chi square.

^b p value obtained by Mann-Whitney’s U.

^c p value obtained by log-rank chi square.

Figure 2. Overall survival of the patients given haploidentical hematopoietic stem cell transplants employing post-transplant cyclophosphamide (Cy) at either 25 or 50 mg/Kg/day on days 3 and 4. Overall survival (OS) was defined as the interval from date of transplant to death and relapse free survival (RFS) was defined as the interval from starting therapy to relapse or death from any cause. The probability of OS and RFS was estimated using the Kaplan–Meier method. The log-rank test was used to compare groups.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.