Clinical efficacy of 177Lu-DOTATATE peptide receptor radionuclide therapy in thyroglobulin-elevated negative iodine scintigraphy: A "not-so-promising" result compared to GEP-NETs

68 Ga-DOTATATE PET/CT Versus 18 F-FDG PET/CT in TENIS Syndrome: A Head-to-Head Comparison With Elevated and Suppressed TSH Levels in Papillary Thyroid Carcinoma-A Pilot Study

BACKGROUND

TENIS syndrome is characterized by reduced expression of sodium-iodine symporter, rising serum thyroglobulin (Tg) levels, and negative whole-body 131 I scans. In such patients, somatostatin receptor imaging with 68 Ga-DOTATATE PET/CT (somatostatin receptor [SSR] PET/CT) and 18 F-FDG PET/CT (FDG PET/CT) can identify metastases and were compared under 2 conditions: elevated (eTSH) and suppressed (sTSH) TSH serum levels. Potential candidates for peptide receptor radionuclide therapy (PRRNT) were identified in 15 patients prospectively enrolled. All patients underwent 4 examinations. Images were blindly evaluated for differences in SUV max values and lesion detectability. Reference standard consisted of neck ultrasound, CT, MRI, PET/CT, biopsy, and follow-up. Three patients were received PRRNT.

RESULTS

sTSH SSR PET/CT detected a greater number of cervical ( P = 0.0253 and P = 0.0176) and distant LNs ( P = 0.0253 and P = 0.0391) when compared with sTSH FDG PET/CT, respectively, in a per-patient and on a per-lesion based analysis. Likewise, eTSH SSR PET/CT detected a greater number of patients with local recurrences ( P = 0.0455) and distant LN metastases ( P = 0.0143). Per-lesion analysis revealed greater number of cervical and distant LNs ( P = 0.0337 and P = 0.0039, respectively) when compared with eTSH FDG PET/CT. There was no difference in detection of distant metastases by both tracers for lung and bone metastases (κ = 1). Both skeletal and pulmonary lesions were also detected by conventional CT part of FDG or DOTATATE PET/CT scans. TSH stimulation had no additional value in a per-patient analysis for both FDG and DOTATATE PET scans (κ varying from 0.6087 to 1). However, TSH stimulation led to more lesion identifications in DOTATATE PET/CT; most of those metastases were not confirmed by the reference standard leading to a decrease in specificity (84% vs 74%). One of 3 patients submitted to 3 cycles of PRRNT presented with a visual partial response, a 20% reduction in quantitative analyses, and stable disease regarding Tg and TgAb levels.

CONCLUSIONS

Patients with TENIS syndrome can be imaged with SSR PET/CT as well as FDG PET/CT with high overall accuracy regardless of TSH levels (86% to 92% and 92% to 85%, respectively, with eTSH and sTSH). SSR PET/CT detected a greater number of locoregional and distant LN metastases than FDG PET/CT with both sTSH and eTSH. One of 3 patients submitted to PRRNT presented a partial response to treatment. Our findings may impact in patient restaging, management, and theranostics strategies with radiolabeled somatostatin analogs.

Assessing Krenning's score on 68 Ga-DOTATATE PET-CT and miPSMA score on 68 Ga-PSMA-11 PET-CT in TENIS: a comparison with FDG PET/CT and examining the feasibility of targeted radionuclide therapy

OBJECTIVES

The objective of this study was to assess receptor expression in metastatic differentiated thyroid carcinoma patients with progressive elevated thyroglobulin and negative iodine scintigraphy, we used 68 Ga-DOTATATE [Gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE)] (Krenning's score) and 68 Ga-PSMA-11 (Gallium-68 prostate-specific membrane antigen-11) PET-computed tomography (CT) [molecular imaging prostate-specific membrane antigen (miPSMA) score]. Patients with Krenning's score 3 and above and miPSMA score 2 and above were considered to determine the incidence of patients, who would qualify for treatment with 177 Lu-DOTATATE/PSMA [Lutetium-177 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE)/prostate-specific membrane antigen]-based therapy. In addition, we compared 68 Ga-DOTATATE and 68 Ga-PSMA-11 PET-CT with 2-deoxy-2-[F-18]fluoroglucose ( 18 F-FDG) PET-CT (using maximum standardized uptake value).

MATERIALS AND METHODS

A total of 74 patients with histopathologically proven metastatic differentiated thyroid carcinoma with thyroglobulin elevation and negative iodine scintigraphy syndrome were studied retrospectively. They all had 18 F-FDG, 68 Ga-DOTATATE, and 68 Ga-PSMA-11 PET-CT scans available for undertaking this analysis. The lesions detected by 68 Ga-DOTATATE and 68 Ga-PSMA-11 were evaluated using Krenning's and miPSMA scores. In addition, quantitative comparisons of maximum standardized uptake values for 68 Ga-DOTATATE and 68 Ga-PSMA-11, as well as with 18 F-FDG, were conducted.

RESULTS

Patient-wise analysis revealed positivity rates of 40.5% for 68 Ga-DOTATATE, 41.89% for 68 Ga-PSMA-11, and 75.67% for 18 F-FDG. Among the 74 patients, 14 (18.91%) were deemed eligible for 177 Lu-DOTATATE/PSMA-617 therapy based on Krenning's score of 3 and above both/either miPSMA score of 2 and above on 68 Ga-DOTATATE or 68 Ga-PSMA-11 PET-CT. Within this subgroup, seven out of 74 patients (9.45%) were eligible for 177 Lu-DOTATATE therapy, and nine out of 74 patients (12.16%) were eligible for 177 Lu-PSMA-targeted therapy. Four patients were eligible for both therapies.

CONCLUSION

Among thyroglobulin elevation and negative iodine scintigraphy patient's subgroup, 9.45% could qualify for 177 Lu-DOTATATE and 12.16% for 177 Lu-PSMA-617. Four were eligible for both therapies. Given the lack of effective therapies, this subset of patients warrants consideration for radionuclide therapy exploration.

Imaging Recommendations for Theranostic PET-CT in Oncology

We in this article have presented a review of the guideline recommendations on theranostic positron emission tomography-computed tomography (PET-CT) imaging which will be helpful to assist practitioners in providing appropriate patient care. Multiple guidelines by different societies and medical associations provide standards for diagnosis, imaging, and treatment of cancer patients. They have generated a number of recommendations related to 68Ga-DOTATATE and 68Ga-PSMA-11 PET-CT, which are the classical examples of theranostic PET-CT imaging in current practice.

Role of PET/Computed Tomography in Elderly Thyroid Cancer: Tumor Biology and Clinical Management

PET/computed tomography (CT) studies can be potentially useful in elderly thyroid carcinoma patients for exploring the disease biology, especially in metastatic setting and thereby directing appropriate therapeutic management on case-to-case basis, adopting nuclear theranostics, and disease prognostication. With the availability of multiple PET radiopharmaceuticals, it would be worthwhile to evolve and optimally use FDG and the other non-fluorodeoxyglucose and investigational PET/CT tracers as per the clinical situation and need and thereby define their utilities in a given case scenario. In this regard, (I) differentiated thyroid carcinoma (DTC) including radioiodine refractory disease, poorly differentiated thyroid cancer (PDTC) and TENIS, (II) medullary thyroid carcinoma (MTC), (III) anaplastic carcinoma and (IV) Primary thyroid lymphoma (PTL) should be viewed and dealt separately.

Personalized Diagnosis in Differentiated Thyroid Cancers by Molecular and Functional Imaging Biomarkers: Present and Future

Personalized diagnosis can save unnecessary thyroid surgeries, in cases of indeterminate thyroid nodules, when clinicians tend to aggressively treat all these patients. Personalized diagnosis benefits from a combination of imagery and molecular biomarkers, as well as artificial intelligence algorithms, which are used more and more in our timeline. Functional imaging diagnosis such as SPECT, PET, or fused images (SPECT/CT, PET/CT, PET/MRI), is exploited at maximum in thyroid nodules, with a long history in the past and a bright future with many suitable radiotracers that could properly contribute to diagnosing malignancy in thyroid nodules. In this way, patients will be spared surgery complications, and apparently more expensive diagnostic workouts will financially compensate each patient and also the healthcare system. In this review we will summarize essential available diagnostic tools for malignant and benignant thyroid nodules, beginning with functional imaging, molecular analysis, and combinations of these two and other future strategies, including AI or NIS targeted gene therapy for thyroid carcinoma diagnosis and treatment as well.

Theranostic Options for Radioiodine-Refractory Differentiated Thyroid Carcinoma: Recent Advances, Challenges, and Road Ahead

Radioiodine-refractory differentiated thyroid cancer (RAIR-DTC), though uncommon, presents a considerable therapeutic challenge with poor long-term outcomes. Currently, tyrosine kinase inhibitors are the mainstay of treatment for advanced RAIR-DTC patients. However, these agents are associated with a multitude of adverse events with resultant deterioration in the quality-of-life of the patients. Targeted theranostic approaches with radiolabelled integrin binders and fibroblast activation protein- (FAP)-inhibitors seem to have a promising role in the management of such patients. This mini-review focuses on these novel theranostic strategies in RAIR-DTC, with emphasis on recent advances, existing challenges, and future directions.

Efficacy and safety of peptide receptor radionuclide therapy in advanced radioiodine-refractory differentiated thyroid cancer and metastatic medullary thyroid cancer: a systematic review

Background

It has been shown that a subgroup of patients with differentiated thyroid cancer (DTC) and medullary thyroid carcinoma (MTC) would progress to advanced stages of thyroid cancer. Therefore, the present study was done to systematically review available evidence in order to investigate efficacy and safety of peptide receptor radionuclide therapy (PRRT) in the patients with advanced radioiodine refractory differentiated thyroid cancer (RR-DTC) and metastatic MTC.

Methods

For this purpose, relevant studies investigated safety and efficacy of PRRT in the patients with advanced RR-DTC and metastatic MTC were identified by searching Medline (Pubmed, Ovid, and Ebsco), Scopus, Embase, Web of Science, and Cochrane Library databases (from database inception to March 24, 2021). The review was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Searching was done independently by two investigators. Two researchers independently extracted the data and any disagreement was adjudicated by consensus. Quality of the studies was assessed using the tool of case reports/series in systematic reviews.

Results

Among 2284 related papers, 41 papers met the inclusion criteria. A total of 157 patients with RR-DTC were treated with PPRT. Biochemical and objective responses (partial and complete) were observed in 25.3 and 10.5% of patients, respectively. Among 220 patients with metastatic MTC, biochemical and objective responses were observed in 37.2 and 10.6% of the patients, respectively.

Forty-six deaths were reported in 95 patients with advanced RR-DTC. In addition, 63 deaths were observed in 144 patients with metastatic MTC. Major side effects were reported in 124 patients treated with ⁹⁰Y -based agent. In the patients treated with 177Lu-DOTA-TATE and 111In-Octreotide, mild and transient hematologic or renal complications were reported.

Conclusion

Findings of the study revealed that in the absence of the established treatment for the patients with RR-DTC and metastatic MTC, PRRT could be effective with few adverse events.

Trial registration

PROSPERO registration number: CRD42019125245.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08257-x.