Reply: Different Radionuclides in DOTA-EB-TATE Effect Different Uptake in Somatostatin Receptor–Positive HEK293 Cells
=======================================================================================================================

* Orit Jacobson
* Xiaoyuan Chen

**REPLY:** We would like to thank Dr. Kotzerke and his colleagues for the important insights into the uptake of DOTA-EB-TATE, an albumin-binding octreotate developed by us (1–4). The results presented by Dr. Kotzerke are of high importance, suggesting that the radiometal chelated into the DOTA moiety affects the uptake and perhaps binding of both DOTA-TATE and EB-DOTA-TATE. The authors concluded that “As a consequence of the different uptake, only different isotopes of the same element (such as 86Y/90Y or 64Cu/67Cu) can be used for assessment of biokinetic data.”

Although the data presented by the authors are intriguing, we would like to argue that: (1) These results are not specific to EB-DOTA-TATE but are seen with DOTA-TATE as well. It is common practice to use 68Ga-DOTA-TATE to detect tumor somatostatin receptor 2 expression before radionuclide therapy with 177Lu-DOTA-TATE, and so far this practice seems to prove itself. Moreover, 68Ga-DOTA-TATE scanning has significantly lower radiation exposure to the patient than other longer-lived isotopes labeled with the same ligand. It would be unreasonable in our opinion to use 86Y for imaging when a much safer option is available (2). The authors derive their conclusion from in vitro cell uptake and extrapolated the result to predict the in vivo pharmacokinetics. It would be more appropriate to draw a conclusion from actual in vivo studies.

We look forward to seeing data from more in-depth in vivo studies done, perhaps, by Dr. Kotzerke and colleagues.

## Footnotes

*   Published online Dec. 20, 2018.

*   © 2019 by the Society of Nuclear Medicine and Molecular Imaging.

## REFERENCES

1.  1.Tian R, Jacobson O, Niu G, et al. Evans blue attachment enhances somatostatin receptor subtype-2 imaging and radiotherapy. Theranostics. 2018;8:735–745.
    
    

2.  2.Bandara N, Jacobson O, Mpoy C, Chen X, Rogers BE. Novel structural modification based on Evans blue dye to improve pharmacokinetics of a somastostatin-receptor-based theranostic agent. Bioconjug Chem. 2018;29:2448–2454.
    
    

3.  3.Zhang J, Wang H, Jacobson O, et al. Safety, Pharmacokinetics, and dosimetry of a long-acting radiolabeled somatostatin analog 177Lu-DOTA-EB-TATE in patients with advanced metastatic neuroendocrine tumors. J Nucl Med. 2018;59:1699–1705.
    
    [Abstract/FREE Full Text](http://jnm.snmjournals.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Njoiam51bWVkIjtzOjU6InJlc2lkIjtzOjEwOiI1OS8xMS8xNjk5IjtzOjQ6ImF0b20iO3M6MjM6Ii9qbnVtZWQvNjAvMy80MzYuMi5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

4.  4.Wang H, Cheng Y, Zhang J, et al. Response to single low-dose 177Lu-DOTA-EB-TATE treatment in patients with advanced neuroendocrine neoplasm: a prospective pilot study. Theranostics. 2018;8:3308–3316.