Thiotepa/cyclophosphamide/TBI as a conditioning regimen for allogeneic hematopoietic stem cell transplantation in patients aged 50 years and over

Pulmonary Toxicity After Total Body Irradiation - Critical Review of the Literature and Recommendations for Toxicity Reporting

INTRODUCTION

Total body irradiation is an effective conditioning regimen for allogeneic stem cell transplantation in pediatric and adult patients with high risk or relapsed/refractory leukemia. The most common adverse effect is pulmonary toxicity including idiopathic pneumonia syndrome (IPS). As centers adopt more advanced treatment planning techniques for TBI, total marrow irradiation (TMI), or total marrow and lymphoid irradiation (TMLI) there is a greater need to understand treatment-related risks for IPS for patients treated with conventional TBI. However, definitions of IPS as well as risk factors for IPS remain poorly characterized. In this study, we perform a critical review to further evaluate the literature describing pulmonary outcomes after TBI.

MATERIALS AND METHODS

A search of publications from 1960-2020 was undertaken in PubMed, Embase, and Cochrane Library. Search terms included "total body irradiation", "whole body radiation", "radiation pneumonias", "interstitial pneumonia", and "bone marrow transplantation". Demographic and treatment-related data was abstracted and evidence quality supporting risk factors for pulmonary toxicity was evaluated.

RESULTS

Of an initial 119,686 publications, 118 met inclusion criteria. Forty-six (39%) studies included a definition for pulmonary toxicity. A grading scale was provided in 20 studies (17%). In 42% of studies the lungs were shielded to a set mean dose of 800cGy. Fourteen (12%) reported toxicity outcomes by patient age. Reported pulmonary toxicity ranged from 0-71% of patients treated with TBI, and IPS ranged from 1-60%. The most common risk factors for IPS were receipt of a TBI containing regimen, increasing dose rate, and lack of pulmonary shielding. Four studies found an increasing risk of pulmonary toxicity with increasing age.

CONCLUSIONS

Definitions of IPS as well as demographic and treatment-related risk factors remain poorly characterized in the literature. We recommend routine adoption of the diagnostic workup and the definition of IPS proposed by the American Thoracic Society. Additional study is required to determine differences in clinical and treatment-related risk between pediatric and adult patients. Further study using 3D treatment planning is warranted to enhance dosimetric precision and correlation of dose volume histograms with toxicities.

Clinical significance of the administration of cytarabine or thiotepa in addition to total body irradiation and cyclophosphamide for allogeneic hematopoietic cell transplantation in patients with acute leukemia

A multicenter retrospective study was performed to determine the significance of adding cytarabine (CA) or thiotepa (TT) in the context of total body irradiation (TBI) and cyclophosphamide (CY). A total of 322 patients who underwent allogeneic hematopoietic cell transplantation (HCT) were distributed to the following three groups: TBI/CY (n = 75), TBI/CY/CA (n = 77), and TBI/CY/TT (n = 170). In the TBI/CY/TT group, 164 of patients (96 %) received HCT during the previous year (2000-2005). Multivariate analysis revealed that the TBI/CY/TT group demonstrated a trend of poorer survival rate than the TBI/CY group, [hazard ratio (HR) = 1.49, 95 % confidence interval (CI) 0.99-2.24, P = 0.055] with a higher non-relapse mortality (NRM) (HR = 2.34, 95 % CI 1.35-4.06, P = 0.002) rates, while TBI/CY/CA group demonstrated similar outcomes. Even in the subgroup analyses of disease type or disease risk, the outcomes with intensified conditioning regimens were not superior to those with TBI/CY. In conclusion, although the significant bias has to be carefully considered, the clinical benefit of adding CA or TT to the TBI/CY regimen was not demonstrated.

Treatment of oral mucositis in hematologic patients undergoing autologous or allogeneic transplantation of peripheral blood stem cells: a prospective, randomized study with a mouthwash containing camelia sinensis leaf extract

Oral mucositis is an important side effect of hematopoietic stem cell transplantation (HCST), mainly due to toxicity of conditioning regimens. It produces significant pain and morbidity. The present study reports a prospective, randomized, non-blinded study testing the efficacy of a new mouthwash, called Baxidil Onco(®) (Sanitas Farmaceutici Srl, Tortona, Italy) in 60 hematologic patients undergoing HCST (28 autologous, 32 allogeneic). Baxidil Onco(®), used three times a day from Day -1 to Day +30, in addition to standard prophylactic schedules, was administered to 14 patients undergoing autologous and 14 patients undergoing allogeneic HCST. The remaining 32 patients (14 autologous and 18 HCST) were treated only with standard prophylactic schedules and served as control. In our study, the overall incidence of oral mucositis, measured according to the World Health Organization 0-4 scale, was 50% in the Baxidl Onco(®) group versus 82% in the control group (P=0.022). In addition, a significant reduction in scale 2-4 oral mucositis was observed in the Baxidil Onco(®) group (25% vs 56.2%; P=0.0029). The results obtained indicate that incidence, severity and duration of oral mucositis induced by conditioning regimens for HCST can be significantly reduced by oral rinsing with Baxidil Onco(®), in addition to the standard prophylaxis scheme. Since Camelia Sinensin extract, which is used to produce green tea, is the main agent in this mouthwash, we hypothesize that the anti-oxidative properties of polyphenolic compounds of tea might exert protective effects on oral mucosa.

Prognostic factors in patients aged 50 years or older undergoing allogeneic hematopoietic stem cell transplantation for hematologic malignancy

We retrospectively analyzed patients aged C 50 years with hematologic malignancies who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) to identify preoperative variables predicting the outcome. There were 71 patients with a median age of 57 years (range: 50-63 years) who had acute leukemia (n = 53) or myelodysplastic syndrome (n = 18). Myeloablative conditioning was done in 35 patients and 36 patients had reduced-intensity conditioning. The 5-year overall survival rate (OS), cumulative relapse rate, and non-relapse mortality rate (NRM) were 45, 24, and 33%, respectively. According to multivariate analysis, high-risk disease (HR 3.50, 95% CI 1.43-8.56, P = 0.006), a hematopoietic cell transplantation comorbidity index (HCT-CI) score ≥ 3 (HR 4.41, 95% CI 1.31-14.77, P = 0.016), and an HLA-mismatched unrelated donor (HR 4.03, 95% CI 1.46-11.10, P = 0.007) were significant predictors of worse OS. Highrisk disease was also significantly associated with a higher cumulative relapse rate (HR 4.59, 95% CI 0.94-6.92, P = 0.065). Furthermore, an HCT-CI score ≥ 3 (HR 3.02, 95% CI 1.01-20.78, P = 0.048) and an HLA-mismatched unrelated donor (HR 3.02, 95% CI 1.04-8.74, P = 0.042) were risk factors for NRM. These results suggest that the disease risk, HCT-CI score, and donor type/histocompatibility are prognostic factors for elderly patients, while the conditioning regimen and age are not predictors.