The relationship of oropharyngeal colonization microorganisms to clinical outcomes within 100 days after allogeneic hematopoietic stem cell transplantation

A clinical predictive model for pre-transplantation Klebsiella pneumoniae colonization and relevance for clinical outcomes in patients receiving allogeneic hematopoietic stem cell transplantation

The purpose of this study is to establish a clinical prediction model to discriminate patients at high risk of Klebsiella pneumoniae (KP) colonization before allogeneic hematopoietic stem cell transplantation (allo-HSCT) and evaluate the impact of KP colonization on clinical outcomes after allo-HSCT. We retrospectively collected data from 2,157 consecutive patients receiving allo-HSCT between January 2018 and March 2022. KP colonization was defined as a positive test for KP from a pharyngeal or anal swab before allo-HSCT. Logistic regression was used to build a clinical prediction model. Cox regression analyses were performed to explore the effect of KP colonization on clinical outcomes. Among all the inpatients, 166 patients had KP colonization and 581 with no positive pathogenic finding before transplantation. Seven candidate predictors were entered into the final prediction model. The prediction model had an area under the curve of 0.775 (95% CI 0.723-0.828) in the derivation cohort and 0.846 (95% CI: 0.790-0.902) in the validation cohort. Statistically significantly different incidence rates were observed among patient groups with clinically predicted low, medium, and high risk for KP infection (P < 0.001). The presence of KP colonization delayed platelet engraftment (P < 0.001) and patients with KP colonization were more likely to develop KP bloodstream infections within 100 days after allo-HSCT (P < 0.0001). Patients with KP colonization had higher non-relapse mortality (P = 0.032), worse progression-free survival (P = 0.0027), and worse overall survival within 100 days after allo-HSCT (P = 0.013). Our findings suggest that increased awareness of risks associated with pre-transplantation bacterial colonization is warranted.IMPORTANCESeveral studies have identified that Klebsiella pneumoniae (KP) is among the most common and deadly pathogens for patients in hospital intensive care units and those receiving transplantation. However, there are currently no studies that evaluate the impact of KP colonization to patients undergoing allogeneic hematopoietic stem cell transplantation. Our results confirm that pre-existing KP colonization is relatively common in a hematology transplant ward setting and negatively affects post-transplantation prognosis. Our clinical prediction model for KP colonization can support early intervention in patients at high risk to avoid subsequent bloodstream infections and improve survival outcomes. Altogether, our data suggest that increased awareness of risks associated with pre-transplantation bacterial colonization is warranted. Future studies are needed to confirm these findings and to test early intervention strategies for patients at risk of complications from KP infection.

Allogenic hematopoietic stem cell transplantation outcomes of patients aged ≥ 55 years with acute myeloid leukemia or myelodysplastic syndromes in China: a retrospective study

BACKGROUND

Elderly patients with acute myeloid leukemia or myelodysplastic syndromes (AML/MDS) have historically had poor prognoses. However, there has been a recent increase in the use of allogenic hematopoietic stem cell transplantation (allo-HSCT) are in this patient population. Nevertheless, the optimal choice of donor type for the patients remains an unmet need. Limited data exist on the use of allo-HSCT in elderly patients with AML/MDS from China. To better understand and optimize the selection of donor type for the elderly patients, particularly for those with refractory or relapsed disease, in comparison with the previous studies in the US and Europe.

METHODS

Our retrospective study enrolled 259 patients aged over 55 years who underwent their first allo-HSCT between April 2015 and August 2022. These patients were divided into three groups based on donor type: haploidentical related donor group (haploidentical related donor transplantation [HID], n = 184), matched sibling donor group (matched sibling donor transplantation [MSD], n = 39), and matched unrelated donor group (matched unrelated donor transplantation [MUD], n = 36). Statistics were performed with the chi-square test, the log-rank and Fine-Gray tests.

RESULTS

The median age of the cohort was 57 years (range: 55-75) and 26.25% of patients were over 60 years old. Younger patients had a higher incidence of acute graft-versus-host disease (HR = 1.942, P = 0.035), faster neutrophil recovery (HR = 1.387, P = 0.012), and better overall survival (HR = 0.567, P = 0.043) than patients aged ≥ 60 years across the entire cohort. Patients with refractory or relapsed (R/R) diseases had delayed neutrophil engraftment (P = 0.010, HR = 0.752) and platelet engraftment (P < 0.001, HR = 0.596), higher incidence of relapses (HR = 2.300, P = 0.013), and inferior relapse-free survival (RFS) (HR = 1.740, HR = 0.016) regardless of donor type. When it came to graft-versus-host-disease-free, relapse-free survival (GRFS), MUDs turned out to be superior to HIDs (HR = 0.472, P = 0.026) according to the multivariable analysis. In contrast, we found MSDs had an inferior GRFS to HIDs in parallel (HR = 1.621, P = 0.043).

CONCLUSION

The choice of donor type did not significantly affect the outcomes of allo-HSCT. However, when considering the quality of post-transplant life, MUDs or HIDs from younger donors may be the optimal choice for elderly patients.

The impact of pre-transplant anti-HLA antibodies in transplants from HLA-identical sibling donors: A multicenter study

Few studies have performed comparative analysis of the outcome of hematopoietic stem cell transplantation from HLA-identical sibling donors (ISD-HSCT) in patients with or without anti-HLA Abs. In this study we retrospectively collected data from a multicenter study to analyze the distribution and impact of the pre-existing anti-HLA Abs in ISD-HSCT. Among 402 recipients, 111 were positive for anti-HLA Abs. Gender, time from diagnosis to transplantation and distribution of primary disease might be risk factors for the occurrence of anti-HLA Abs. We found that patients with anti-HLA Abs had delayed neutrophil engraftment and were more vulnerable to experience Cytomegalovirus (CMV) reactivation. The presence of anti-HLA Abs was proved to be an independent risk factor for neutrophil engraftment (HR 1.42 95% CI 1.13-1.80, p = 0.003) and CMV reactivation (HR 2.03 95% CI 1.19-3.46, p = 0.009). We found that anti-HLA Abs have a negative impact on the prognosis in the early period after transplantation from sibling donors and anti-HLA Abs was also an independent risk factor for the overall survival (OS) at 180 days (HR 2.32, 95% CI 1.03-5.27, p = 0.042) among female recipients. In conclusion, anti-HLA Abs have a negative impact on the prognosis early after ISD-HSCT.

What We Learn from Surveillance of Microbial Colonization in Recipients of Pediatric Hematopoietic Stem Cell Transplantation

Infections in hematopoietic stem cell transplant (HSCT) remain one of the major causes for morbidity and mortality, and it is still unclear whether knowledge of microbial colonization is important. In this single-center study, we collected weekly surveillance cultures in pediatric recipients of allogenic HSCT from five different body regions and tested for bacteria and fungi. Between January 2010 and December 2021, we collected 1095 swabs from 57 recipients of allogeneic HSCTs (median age: 7.5 years, IQR 1−3: 2.5−11.9). The incidence of positive microbiological cultures (n = 220; 20.1%) differed according to the anatomic localization (p < 0.001) and was most frequent in the anal region (n = 98), followed by the genital, pharyngeal and nasal regions (n = 55, n = 37 and n = 16, respectively). Gram-positive bacteria (70.4%) were the most commonly isolated organisms, followed by fungi (18.6%), Gram-negative (5.5%), non-fermenting bacteria (1.4%), and other flora (4.1%). No association with increased risk of infection (n = 32) or septicemia (n = 7) was noted. Over time, we did not observe any increase in bacterial resistance. We conclude that there is no benefit to surveillance of microbial colonization by culture-based techniques in pediatric HSCT. Sequencing methods might enhance the detection of pathogens, but its role is still to be defined.

The impact of Rituximab administered before transplantation in patients undergoing allogeneic hematopoietic stem cell transplantation: A real-world study

Rituximab is used to eliminate B cells as a chimeric monoclonal antibody directed against CD20, a B-cell antigen expressed on B cells. To explore the impact of rituximab administered before transplantation, we implemented a retrospective, monocentric study and utilized real-world data collected at our center between January 2018 and December 2020, and then followed until December 2021. Based on whether a dose of 375mg/m2 rituximab was used at least once within two weeks before transplantation, patients undergoing allo-HSCT were classified into two groups: rituximab (N=176) and non-rituximab (N=344) group. Amongst all the patients, the application of rituximab decreased EBV reactivation (P&lt;0.01) and rituximab was an independent factor in the prevention of EBV reactivation by both univariate and multivariate analyses (HR 0.56, 95%CI 0.33-0.97, P=0.04). In AML patients, there were significant differences in the cumulative incidence of aGVHD between the two groups (P=0.04). Our data showed that rituximab was association with a decreased incidence of aGVHD in AML patients according to both univariate and multivariate analyses. There was no difference between the two groups in other sets of populations. Thus, our study indicated that rituximab administered before transplantation may help prevent EBV reactivation in all allo-HSCT patients, as well as prevent aGVHD in AML patients after allo-HSCT.