Utilizing radiopharmaceuticals made by Pars Isotope Co. for the feasibility and investigation of the therapeutic potential of (Ga-68/Lu-177)-DOTATATE theranostic pair in patients with metastatic medullary thyroid carcinoma.

A group of nuclear medicine and oncology experts recently published a study regarding the clinical efficacy of somatostatin receptor imaging with Ga-68-DOTATATE radiopharmaceutical for the diagnosis of medullary thyroid carcinoma (MTC), as well as investigating the therapeutic efficacy of peptide receptor radionuclide therapy (PRRT) with Lu-177-DOTATATE in MTC patients.

In this research, experts from different research centers in Iran, such as Persian Gulf Nuclear Medicine Research Center,Bushehr, Department of Oncology, Salman-Farsi Hospital, Bushehr and Cancer Research Center, RAZAVI Hospital, Mashhad, used radiopharmaceuticals products of Pars Isotope Company.

Medullary thyroid carcinoma (MTC), which originates from the perifollicular cells of the thyroid gland responsible for calcitonin production, is a rare neuroendocrine tumor (NET). It accounts for 5–8% of all thyroid cancers, and occurs in hereditary and sporadic forms. Serum calcitonin level is the most sensitive and specific tumor marker for preoperative diagnosis and follow-up of MTC; it can reveal the volume of the disease but does not locate the lesion. MTC has a worse prognosis than the more common differentiated thyroid cancers. The primary issues regarding this malignancy are locating and detecting recurrent disease, particularly given the high recurrence rate of up to 50%.

In about 40% of cases, combined use of several imaging modalities (computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US), and bone scintigraphy) enables lesion detection and location. Diagnostic imaging is usually negative in patients with serum calcitonin levels < 150 pg/mL, while the detection rate increases with increasing calcitonin level.

Several radiotracers have been evaluated for the detection of MTC in nuclear imaging: Such as F-18 group radiopharmaceuticals or radiopharmaceuticals that involve the somatostatin receptors (SSTR), such as Ga-68-DOTATATE as PET radiopharmaceuticals, and Tc-99m-DMSA, I-123/I-131-MIBG as SPECT radiopharmaceuticals.

Like in other NETs, SSTRs are overexpressed in the cell membrane in more than 75% of MTCs. Therefore, radiopharmaceuticals with peptides specific to somatostatin receptors have been evaluated in recent years as a diagnostic or therapeutic option for MTC. Although they may show lower detection efficacy than other radiotracers (e.g., 18F-DOPA) in MTC, they are currently more popular due to their theranostic features enabling both diagnosis and treatment.

The aim of this study, which was conducted using our radiopharmaceutical products, was to investigate the clinical effectiveness of PET/CT imaging of somatostatin receptors using Ga-68-DOTATATE radiopharmaceutical for the diagnosis of MTC tumors and also to evaluate the effectiveness of treatment using Lu-177-DOTATATE radiopharmaceutical in patients with MTC. The results indicated that PET/CT imaging using Ga-68-DOTATAE has a relatively high detection rate. Furthermore, treatment using Lu-177-DOTATATE can be considered as a safe alternative for the treatment of MTC.