Assessment of γ-H2AX and 53BP1 Foci in Peripheral Blood Lymphocytes to Predict Subclinical Hematotoxicity and Response in Somatostatin Receptor-Targeted Radionuclide Therapy for Advanced Gastroenteropancreatic Neuroendocrine Tumors

Abstract

Background: We aimed to characterize γ-H2AX and 53BP1 foci formation in patients receiving somatostatin receptor-targeted radioligand therapy, and explored its role for predicting treatment-related hematotoxicity, and treatment response. Methods: A prospective analysis of double-strand break (DSB) markers was performed in 21 patients with advanced gastroenteropancreatic neuroendocrine tumors. γ-H2AX and 53BP1 foci formation were evaluated in peripheral blood lymphocytes (PBLs) at baseline, +1 h and +24 h after administration of 7.4 GBq (177Lu)Lu-DOTA-TATE. Hematotoxicity was evaluated using standard hematology. Therapy response was assessed using (68Ga)Ga-DOTA-TATE PET/CT before enrollment and after 2 cycles of PRRT according to the volumetric modification of RECIST 1.1. Results: DSB marker kinetics were heterogeneous among patients. Subclinical hematotoxicity was associated with γ-H2AX and 53BP1 foci formation (e.g., change in platelet count vs change in γ-H2AX+ cells between baseline and +1 h (r = −0.6080; p = 0.0045). Patients showing early development of new metastases had less γ-H2AX (p = 0.0125) and less 53BP1 foci per cell at +1 h (p = 0.0289), and demonstrated a distinct kinetic pattern with an absence of DSB marker decrease at +24 h (γ-H2AX: p = 0.0025; 53BP1: p = 0.0008). Conclusions: Assessment of γ-H2AX and 53BP1 foci formation in PBLs of patients receiving radioligand therapy may hold promise for predicting subclinical hematotoxicity and early treatment response.

Comparison of pretherapeutic osseous tumor volume and standard hematology for prediction of hematotoxicity after PSMA-targeted radioligand therapy

“…This patient, however, showed no lymphocytopenia after one cycle of radioligand therapy. MIP maximum intensity projection, SUV standardized uptake value subject of future studies [20]. However, similar to our study, previous reports showed that the frequency of thrombocytopenia and leukocytopenia in patients under RLT is rather low [5,8,15,19].…”

Individual radiosensitivity reflected by γ-H2AX and 53BP1 foci predicts outcome in PSMA-targeted radioligand therapy

“…As part of the study procedure, dedicated blood samples for the evaluation of DDR-markers were collected before administration of [ 177 Lu]Lu-PSMA-I&T, + 1 h after administration and + 24 h after administration. Blood samples were prepared as previously described in [22]. In brief, after isolating PBLs through Ficoll (GE Healthcare, Chicago, IL, USA) density-gradient from EDTA blood, PBLs from mCRPC patients were frozen in an RPMI1640 medium with 15% fetal calf serum 500 U/ml penicillin, 0.5 mg/ml streptomycin, and 2 mM l-glutamine, supplemented with 10% glycerol at − 80 °C until further use.…”

“…Finally, DAPI (Invitrogen) was used to counterstain DNA and cells were mounted with ProLong® Gold (Invitrogen). Further details can be found in [22].…”

“…Cells demonstrating apoptotic morphology or an intensely stained nucleus were excluded from the analysis. In addition, monocytes and granulocytes were excluded from the analysis according to morphological criteria as described in [22]. DDR-markers related to intact PBLs were summed up and divided by the total number of PBLs to access the number of foci per cell.…”

“…Marked interindividual heterogeneity on both amount and kinetics of DNA damage response (DDR) foci during [ 177 Lu]Lu-PSMA RLT was also reported [19,20]. Given the broad range of measured γ-H2AX and 53BP1 levels potentially reflecting individual radiosensitivity, these parameters may also hold potential for risk stratification, serving as "liquid biopsy" to identify patients that most likely benefit from RLT [21,22].…”