[¹⁷⁷Lu]Lu-DOTATATE May Resensitize Neuroendocrine Tumors to Hormonal Therapy: Initial Clinical Experience in Renal Carcinoid

A 65-y-old woman was diagnosed with grade I right renal carcinoid after right nephrectomy. For anonymous publication of her case in this article, written informed consent was obtained from the patient. After 2 y of lanreotide treatment, therapy was discontinued because of unresponsiveness. Two weeks after discontinuation, PET/CT revealed a single [⁶⁸Ga]-DOTATOC–avid infrahepatic mass and widespread bone marrow metastases (Fig. 1A). Two [¹⁷⁷Lu]Lu-DOTATATE doses (7.4 GBq each, 2 mo apart) were administered without adverse effects (Fig. 1B). Posttherapeutic PET/CT revealed intensified persistent disease. Despite stable infrahepatic mass morphology, new femoral bone marrow lesions and fused nearby pelvic lesions suggested unresponsiveness (Fig. 1C). Lanreotide was reintroduced (once every 4 wk), followed by serial PET/CT every 3 cycles (Fig. 1D). The studies revealed gradual partial disease improvement, with overall lower [⁶⁸Ga]-DOTATOC expression and a morphologically regressive infrahepatic mass (Fig. 1D). Two-year follow-up was completed with continued lanreotide maintenance.

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FIGURE 1.

(A) Baseline PET/CT revealed single [⁶⁸Ga]-DOTATOC–avid infrahepatic mass (straight arrow) and widespread bone marrow metastases (curved arrows). (B) Satisfactory disease localization was evident on [¹⁷⁷Lu]Lu-DOTATE SPECT. (C) Posttherapeutic [⁶⁸Ga]-DOTATOC PET/CT revealed intensified persistent disease and fused nearby pelvic lesions (asterisks). (D) Subsequent follow-up [⁶⁸Ga]-DOTATOC images showed gradual partial response. PRRT = peptide receptor radiopharmaceutical therapy.

This case demonstrated the safety of [¹⁷⁷Lu]Lu-DOTATATE in a single-kidney patient with renal carcinoid tumors. Intensified persistent disease after [¹⁷⁷Lu]Lu-DOTATATE treatment was noted, possibly because of a flare response (1) or altered biodistribution after lanreotide withdrawal (2). The gradual disease response after lanreotide reintroduction might suggest a [¹⁷⁷Lu]Lu-DOTATATE–mediated resensitization effect, or it may be a long-lasting [¹⁷⁷Lu]Lu-DOTATATE delayed response effect. Further investigation is needed to explore the possibility of resensitization, a potential feature of targeted therapy (3).

• © 2024 by the Society of Nuclear Medicine and Molecular Imaging.

• Received for publication January 22, 2024.
• Accepted for publication April 29, 2024.