Demographics
A total of 251 pairs of recipients and donors were enrolled in this study, all of whom received haploidentical transplantation. Their characteristics are summarized in Table 1. Overall, there were 140 (55.8%) males and 111 (44.2%) females with a median age of 28 (2–63) years. Among the patients, 77 (30.7%) were children, and 174 (69.3%) were adults. Among the donors, 190 (75.7%) were males, and 61 (24.3%) were females, with a median age of 36 (4–64) years. The median doses of infused mononuclear cells and CD34 + cells were 8.74 (6.16–13.97) × 108/kg recipient body weight and 2.76 (0.68–6.03)× 106/kg recipient body weight, respectively.
Transplantation outcome of the overall cohort
Engraftment
Two patients died within 28 days of transplantation, and one who had poor graft function died in the early stage of transplantation, while the 248 remaining patients all achieved neutrophil engraftment, with a median time of 15 (9–46) days after transplantation. In addition, 235 out of 251 patients (93.6%) achieved successful platelet engraftment, with a median time of 18 (7-237) days after transplantation.
GVHD
A total of 180 patients (71.7%) developed acute GVHD, and 154 (61.4%) were grades I-II, while 26 (10.4%) were grades III-IV. The median time from transplantation to onset of aGVHD was 28 (8–98) days. The cumulative incidence of aGVDH at 30 days and 100 days was 51.9% (95%CI: 34.5%~69.3%) and 68.7% (95%CI: 53.6%~83.8%), respectively (Fig. 1A). In the overall population, 63 patients (25.1%) developed chronic GVHD, with a median time of 201 (104–730) days, and the 1-year cumulative incidence was 22.4% (95%CI: 22.3%~22.5%).
Survival
The median follow-up time was 786 (16-1592) days. There were 58 deaths during this study, resulting in an overall mortality rate of 23.1% (58/251), and 12 deaths (54.5%) in IFD patients. The two-year OS was 77.5% (95%CI: 73.1%~82.2%; Fig. 1B), and DFS was 68.7% (95%CI: 63.9%~73.5%; Fig. 1C).
Relapse
In all, 45 (20.9%) patients relapsed at a median time of 223 (30-1014) days post-transplantation. The two-year cumulative incidence of relapse (CIR) was 17.5% (95%CI: 16.7%~18.3%; Fig. 1D).
Treatment-related mortality
There were 33 (13.1%) patients who died due to treatment-related mortality (TRM), and the two-year cumulative TRM was 14.5% (95%CI: 13.9%~15.1%; Fig. 1E).
The characteristics of IFD
A total of 22 patients (8.8%) diagnosed with IFD are shown in Table 2. The incidence of proven and probable IFD was 2.79% (7/251) and 5.98% (15/251), respectively. The six-month cumulative incidence of IFD was 7.96 (95%CI:7.49%-8.43%), and the one-year cumulative incidence was 8.30% (95%CI:7.81%-8.79%). The median onset time was 59 (9 ~ 262) days after transplantation. Of the all IFD patients, nine developed IFD within 30 days after transplantation, 12 developed it within six months (41–170 days), and one incidence occurred later than six months (262 days) after transplantation. In the proven/probable IFD cases, 15 (68.2%) developed in the respiratory tract, three (13.6%) in blood, three (13.6%) in the central nervous system, and one (4.5%) in the digestive tract. The causal fungal species was identified in only eight patients, including Aspergillus (2/8, 25.0%), Candida (3/8, 37.5%), and non-Aspergillus molds infections (3/8, 37.5% [including one Rhizopus, one Mucorales, and one Absidia orchidis infection]).
Eleven IFD patients died. Of the 11 patients, eight died due to infection, which included three who died due to serious fungal infection, one due to diffuse alveolar hemorrhage, and two due to multiple organ failure. Compared with patients without IFD, patients with IFD experienced poor overall survival, with a one-year OS of 52.0% (95%CI: 32.4%~71.6%) vs. 82.6%(95%CI: 78.7%~86.5%; P < 0.01; Fig. 2A). The one-year DFS were 48.0% (95%CI: 28.4%~49.96%) for IFD patients and 71.7% (95%CI: 57.4%~86.0%) for no-IFD patients, respectively (P < 0.01; Fig. 2B). Among the IFD patients, three relapsed at a median time of 175 (93–308) days. The one-year CIR was 12.0% (95%CI: 11.2%~12.8%), while without IFD, the one-year CIR was 18.1% (95%CI: 18.0%~18.2%; P = 0.42; Fig. 2C). The one-year cumulative incidence of TRM in IFD and no-IFD patients was 40.0% (95%CI: 38.1%~41.9%) and 10.8 (95%CI: 10.7%~10.9%), respectively (P < 0.01; Fig. 2D).
Risk factors of IFD
Risk factors for IFD among clinical characteristics of transplant recipients and polymorphisms of recipients and donors are presented in Table 3. There were no significant differences in pre-transplant variables including gender, underlying disease, and donor–recipient ABO blood type or post-transplant variables including neutrophil engraftment, chronic GVHD, and Epstein–Barr virus. In the univariate analysis, recipient age (>16 years), CMV reactivation, acute GVHD (grades 0-2 and 3-4), and polymorphisms of rs1554013, rs2243283, rs419598, rs4804800, rs2305619, and rs7248637 for recipients and rs7309123, rs419598, rs3921, rs4257674, and rs2305619 for donors were risk factors for proven and probable IFD after transplantation (P<0.1). In multivariate analysis, the independent risk factors for IFD were grades 3-4 aGVHD, CMV reactivation, recipient rs2305619. and donor rs2305619 (PTX3; P<0.05).
Among the 22 IFD patients, 16 (72.7%) developed grades 0-2 and five (22.7%) developed grades 3-4 acute GVHD, and the cumulative incidence of IFD was significantly higher in grades 3-4 aGVHD than in grades 0-2 aGVHD at 30 days (12.8% versus 3.8%) and at 100 days (16.0% versus 10.0%; P=0.009; Figure 3A).
In all, 164 (65.3%) of 251 patients showed cytomegalovirus reactivation, with a median time of 44 (10-270) days, and among IFD patients, 20 (90.9%) showed CMV reactivation. The cumulative incidence of IFD in CMV patients compared with no-CMV patients at 100 days and one year was 9.9% versus 2.8% and 11.1% versus 4.3%, respectively (P=0.026; Figure 3B).
The impact of SNP on IFD
Forty-three SNPs of the recipient and 43 SNPs of the donor in the genomic DNA were genotyped. Recipient and donor rs2305619 (PTX3) were found to be significantly associated with susceptibility to IFD. In the overall IFD population, five patients (22.7%) were heterozygous (GA), 16 patients (72.7%) were homozygous (AA/GG) for PTX3 of the recipient, and one patient was missing data. The 30-day and 100-day cumulative incidence of IFD in homozygous and heterozygous patients was 5.4% versus 1.7% and 11.7% versus 3.4%, respectively (P=0.035; Figure 3C). Furthermore, seven patients (31.8%) were heterozygous (GA), and 15 patients (68.2%) were homozygous (GG/AA) for PTX3 of the donor. The cumulative incidence in homozygous individuals was higher compared to heterozygous individuals at 30 days and at 100 days (5.4% versus 2.5% and 10.1% versus 5.9%; P=0.046; Figure 3D). However, there was no significant difference in PTX3 on OS, and the one-year OS in homozygous and heterozygous patients and donors was 78.1% (95%CI: 70.9%~85.4%) and 81.2% (95%CI: 74.1%~88.3%; P=0.301), 84.4% (95%CI: 77.9 %~90.0%), and 74.4% (95%CI: 66.6%~82.2%; P=0.100), respectively.
Score system
Based on the independent predictors of IFD, we combined the variables (grades 3-4 aGVHD, CMV reactivation, PTX3 of recipients and donors) to develop the IFD scoring system to evaluate the incidence of IFD and stratified patients into low (0-2) and high (3-4) groups. The 30-day cumulative incidence of IFD in the low and high groups was 2.1% and 10.2%, and the 100-day cumulative incidence was 4.2% and 20.3%, respectively (P=0.015; Figure 4A). Additionally, we combined homozygous PTX3 for both recipients and donors (R+/D+) to compare the incidence of IFD with heterozygous group (R-/D+, R+/D-, R-/D-), and the 30-day and 100-day cumulative incidence of IFD were 7.9% and 2.3% and 15.8% and 4.6%, respectively (P=0.01; Figure 4B). Therefore, the scoring system could be used to target patients for enhanced prophylaxis and early antifungal therapy.