Prognostic value of ^(18)F-fluorodeoxyglucose positron emission tomography using Deauville criteria in diffuse large B cell lymphoma treated with autologous hematopoietic stem cell transplantation

Objective: High-dose chemotherapy(HDC) followed by autologous hematopoietic stem cell transplantation(auto-HSCT) plays an important role in improving outcomes of diffuse large B cell lymphoma(DLBCL) patients.18 F-fluorodeoxyglucose(18 F-FDG) positron emission tomography(PET)/computed tomography(CT) has been widely accepted in response assessment and prediction of prognosis in DLBCL. Here, we report the value of 18 FFDG PET/CT pre-and post-HSCT in predicting outcomes of patients with DLBCL.Methods: DLBCL patients who had PET/CT scan before and after HSCT were included. PET results were interpreted based upon Deauville criteria. The prognostic value of 18 F-FDG PET/CT in auto-HSCT was evaluated.Results: Eighty-four patients were enrolled. In univariate analysis, pre-and post-HSCT PET findings were correlated with 3-year progression-free survival(PFS) [hazard ratio(HR)=4.391, P=0.001; HR=7.607, P<0.001] and overall survival(OS)(HR=4.792, P=0.008; HR=26.138, P<0.001). Patients receiving upfront auto-HSCT after firstline treatment had better outcomes than relapsed/refractory DLBCL patients(3-year PFS, P<0.001; 3-year OS,P<0.001). In the relapsed/refractory patients, pre-and post-HSCT PET findings were also associated with 3-year PFS(P=0.003 vs. P<0.001) and OS(P=0.027 vs. P<0.001). A significant correlation was observed between clinical response to chemotherapy before auto-HSCT and outcomes of patients in the entire cohort(3-year PFS, P<0.001;3-year OS, P<0.001) and in the subgroup of 21 patients with positive pre-HSCT PET(3-year PFS, P=0.084; 3-year OS, P=0.240). A significant association between survival and post-HSCT PET findings was observed in multivariate analysis(HR=5.168, P<0.001).Conclusions: PET results before and after HSCT are useful prognostic factors for DLBCL patients receiving HSCT. Patients who responded to chemotherapy, even those with positive pre-HSCT PET, are appropriate candidates for auto-HSCT.

Influence of chelator and near-infrared dye labeling on biocharacteristics of dual-labeled trastuzumab-based imaging agents

Objective： To investigate the effect of fluorescent dye labeling on the targeting capabilities of 111 In- （DTPA）.-trastuzumab-（IRDye 800）m. Methods： Trastuzumab-based conjugates were synthesized and conjugated with diethylenetriaminepentaacetic acid （DTPA） at molar ratios of I, 2, 3 and 5 and with a fluorescent dye （IRDye 800CW） at molar ratios of 1, 3 and 5. Immunoreactivity and internalization were assessed on SKBR-3 cells, overexpressing human epidermal growth factor receptor 2. The stability in human serum and phosphate-buffered saline （PBS） was evaluated. The biodistribution of dual-labeled conjugates was compared with that of 111In-（DTPA）2-trastuzumab in a SKBR-3 xenograft model to evaluate the effect of dye-to-protein ratio. Results： All trastuzumab-based conjugates exhibited a high level of chemical and optical purity. Flow cytometry results showed that increasing dye-to-protein ratios were associated with decreased immunoreactivity. Stability studies revealed that the conjugate was stable in PBS, while in human serum, increased degradation and protein precipitation were observed with increasing dye-to-protein ratios. At 4 h, the percentages of internalization of dual-labeled conjugates normalized by dye-to-protein ratio （m） were 24.88%±2.10%, 19.99%±0.59%, and 17.47%±1.26% for ＂m＂ equal to 1, 3, and 5, respectively. A biodistribution study revealed a progressive decrease in tumor uptake with an increase in the dye-to-protein ratios. The liver, spleen and kidney showed a marked uptake with increased dye-to-protein ratios, particularly in the latter. Conclusions： With non-specific-site conjugation of the fluorescent dye with a protein based on imaging agent, the increase in dye-to-protein ratios negatively impacted the immunoreactivity and stability, indicating a reduced tumor uptake.