Automated radiosynthesis, quality control, and biodistribution of Ga-68 pentixafor: First Indian experience

Background: Chemokine receptor CXCR4 is overexpressed in more than 27 different human tumors that make it a promising target in oncology. Ga-68 Pentixafor is the most promising positron emission tomography tracer for imaging CXCR4 receptors; hence, the present study was carried out to optimize the radiosynthesis of Ga-68-Pentixafor using fully automated method and the quality control (QC) checks were performed before being used as a clinical product. We also studied the normal biodistribution pattern of Ga-68-pentixafor intended for the use in variety of malignancies. Materials and Methods: We optimized the automated radio-synthesis of Ga-68 Pentixafor under good manufacturing practice conditions. A total of 62 productions were carried out in a span of 4 years. Extensive QC tests were performed to check for potency, identity, efficacy, and stability of the tracer. Biodistribution of Ga-68 Pentixafor was investigated in a healthy volunteer to determine normal range of standardized uptake valuemaximum (SUVmax) values in various organs. Results: The radiotracer was prepared successfully in 57/62 productions with radiochemical purity of >99%. Mean radiolabelling efficiency of 73.1% +/- 7.7% (n = 57) was obtained with synthesis time approximatively of 34 min. The radiolabeled complex showed no signs of dissociation up to 4 h at the room temperature. Ga-68 Pentixafor upon incubation with human serum was found to be stable at 37 degrees C for 4 h. The highest normal organ uptake was seen in urinary bladder (SUVmean = 146.0), spleen (SUVmean = 6.80) followed by kidneys (SUVmean = 4.99). Conclusion: Using the automated radiosynthesis, Ga-68 Pentixafor exhibited good radiolabelling efficiency with excellent in vitro and in vivo stability and favorable biodistribution showing clinical applicability of the tracer.

Automated summary

This study successfully optimized the automated radiosynthesis of Ga-68 Pentixafor and conducted extensive quality control tests. The biodistribution study in a healthy volunteer showed good in vivo stability of the tracer, indicating its excellent clinical applicability.