Comparative Radiolabelling of PSMA I&T and Somatostatin Analogues with ¹⁷⁷Lu and ⁹⁰Y: The Impact of SPE Purification

<title>Abstract</title> <p> Background We report on comparison of two automated production processes for radiolabelling and formulation of three different radiopharmaceuticals [ ¹⁷⁷ Lu]Lu-PSMA I&amp;T, [ ¹⁷⁷ Lu]Lu-DOTA-TATE and [ ⁹⁰ Y]Y-DOTA-TOC. These processes were evaluated with and without C-18 solid phase extraction purification. Methods Radiopharmaceuticals were produced and formulated using single use cassette approaches on Eckert &amp; Ziegler’s Modular-Lab PharmTracer synthesis module. Quality control data from 20 to 30 batches for each radiopharmaceutical was used to evaluate these two production methods, including RP-HPLC, iTLC and GC analyses. Results Significant differences of product formulations were found in the amounts of unbound radiometal species as well as ethanol concentrations, although all batches analysed confirmed to pharmacopeial and internal specifications for product release. Radiochemical purity according to RP-HPLC showed no significant variations between the two production procedures. However, a slight increase in formation of a radiolytic side product during solid phase extraction purification of [ ¹⁷⁷ Lu]Lu-PSMA I&amp;T was noticeable. Conclusions Overall, in our setting omission of product purification from automated radiopharmaceutical production did not lead to any significant changes of the quality of the final products for all three radiotracers evaluated in this work. All batches analysed met specifications for product release. Thus, our data indicate that product purification is not required in all production procedures involving preparation of radiopharmaceuticals for radioligand therapy. However, this decision must be based on a case-by-case evaluation for each synthesis module and radiopharmaceutical in question. </p>