177Lu-DOTATATE Therapy in Radioiodine-refractory Differentiated Thyroid Cancer: A Single Center Experience

Positron Emission Tomography/Computed Tomography in Thyroid Cancer: An Updated Review

PET/computed tomography (CT) is a valuable hybrid imaging modality for the evaluation of thyroid cancer, potentially impacting management decisions. 18F-fluorodeoxyglucose (FDG) PET/CT has proven utility for recurrence evaluation in differentiated thyroid cancer (DTC) patients having thyroglobulin elevation with negative iodine scintigraphy. Aggressive histologic subtypes such as anaplastic thyroid cancer shower higher FDG uptake. 18F-FDOPA is the preferred PET tracer for medullary thyroid cancer. Fibroblast activation protein inhibitor and arginylglycylaspartic acid -based radiotracers have emerged as promising PET agents for radioiodine refractory DTC patients with the potential for theranostic application.

Predicting [177Lu]Lu-HA-DOTATATE kidney and tumor accumulation based on [68Ga]Ga-HA-DOTATATE diagnostic imaging using semi-physiological population pharmacokinetic modeling

BACKGROUND

Prediction of [177Lu]Lu-HA-DOTATATE kidney and tumor uptake based on diagnostic [68Ga]Ga-HA-DOTATATE imaging would be a crucial step for precision dosing of [177Lu]Lu-HA-DOTATATE. In this study, the population pharmacokinetic (PK) differences between [177Lu]Lu-HA-DOTATATE and [68Ga]Ga-HA-DOTATATE were assessed and subsequently [177Lu]Lu-HA-DOTATATE was predicted based on [68Ga]Ga-HA-DOTATATE imaging.

METHODS

A semi-physiological nonlinear mixed-effects model was developed for [68Ga]Ga-HA-DOTATATE and [177Lu]Lu-HA-DOTATATE, including six compartments (representing blood, spleen, kidney, tumor lesions, other somatostatin receptor expressing organs and a lumped rest compartment). Model parameters were fixed based on a previously developed physiologically based pharmacokinetic model for [68Ga]Ga-HA-DOTATATE. For [177Lu]Lu-HA-DOTATATE, PK parameters were based on literature values or estimated based on scan data (four time points post-injection) from nine patients. Finally, individual [177Lu]Lu-HA-DOTATATE uptake into tumors and kidneys was predicted based on individual [68Ga]Ga-HA-DOTATATE scan data using Bayesian estimates. Predictions were evaluated compared to observed data using a relative prediction error (RPE) for both area under the curve (AUC) and absorbed dose. Lastly, to assess the predictive value of diagnostic imaging to predict therapeutic exposure, individual prediction RPEs (using Bayesian estimation) were compared to those from population predictions (using the population model).

RESULTS

Population uptake rate parameters for spleen, kidney and tumors differed by a 0.29-fold (15% relative standard error (RSE)), 0.49-fold (15% RSE) and 1.43-fold (14% RSE), respectively, for [177Lu]Lu-HA-DOTATATE compared to [68Ga]Ga-HA-DOTATATE. Model predictions adequately described observed data in kidney and tumors for both peptides (based on visual inspection of goodness-of-fit plots). Individual predictions of tumor uptake were better (RPE AUC -40 to 28%) compared to kidney predictions (RPE AUC -53 to 41%). Absorbed dose predictions were less predictive for both tumor and kidneys (RPE tumor and kidney -51 to 44% and -58 to 82%, respectively). For most patients, [177Lu]Lu-HA-DOTATATE tumor accumulation predictions based on individual PK parameters estimated from diagnostic imaging outperformed predictions based on population parameters.

CONCLUSION

Our semi-physiological PK model indicated clear differences in PK parameters for [68Ga]Ga-HA-DOTATATE and [177Lu]Lu-HA-DOTATATE. Diagnostic images provided additional information to individually predict [177Lu]Lu-HA-DOTATATE tumor uptake compared to using a population approach. In addition, individual predictions indicated that many aspects, apart from PK differences, play a part in predicting [177Lu]Lu-HA-DOTATATE distribution.

Radioiodine therapy in advanced differentiated thyroid cancer: Resistance and overcoming strategy

Thyroid cancer is the most prevalent endocrine tumor and its incidence is fast-growing worldwide in recent years. Differentiated thyroid cancer (DTC) is the most common pathological subtype which is typically curable with surgery and Radioactive iodine (RAI) therapy (approximately 85%). Radioactive iodine is the first-line treatment for patients with metastatic Papillary Thyroid Cancer (PTC). However, 60% of patients with aggressive metastasis DTC developed resistance to RAI treatment and had a poor overall prognosis. The molecular mechanisms of RAI resistance include gene mutation and fusion, failure to transport RAI into the DTC cells, and interference with the tumor microenvironment (TME). However, it is unclear whether the above are the main drivers of the inability of patients with DTC to benefit from iodine therapy. With the development of new biological technologies, strategies that bolster RAI function include TKI-targeted therapy, DTC cell redifferentiation, and improved drug delivery via extracellular vesicles (EVs) have emerged. Despite some promising data and early success, overall survival was not prolonged in the majority of patients, and the disease continued to progress. It is still necessary to understand the genetic landscape and signaling pathways leading to iodine resistance and enhance the effectiveness and safety of the RAI sensitization approach. This review will summarize the mechanisms of RAI resistance, predictive biomarkers of RAI resistance, and the current RAI sensitization strategies.

A physiologically based pharmacokinetic model for [68Ga]Ga-(HA-)DOTATATE to predict whole-body distribution and tumor sink effects in GEP-NET patients

BACKGROUND

Little is known about parameters that have a relevant impact on (dis)similarities in biodistribution between various ⁶⁸Ga-labeled somatostatin analogues. Additionally, the effect of tumor burden on organ uptake remains unclear. Therefore, the aim of this study was to describe and compare organ and tumor distribution of [⁶⁸Ga]Ga-DOTATATE and [⁶⁸Ga]Ga-HA-DOTATATE using a physiologically based pharmacokinetic (PBPK) model and to identify factors that might cause biodistribution and tumor uptake differences between both peptides. In addition, the effect of tumor burden on peptide biodistribution in gastroenteropancreatic (GEP) neuroendocrine tumor (NET) patients was assessed.

METHODS

A PBPK model was developed for [⁶⁸Ga]Ga-(HA-)DOTATATE in GEP-NET patients. Three tumor compartments were added, representing primary tumor, liver metastases and other metastases. Furthermore, reactions describing receptor binding, internalization and recycling, renal clearance and intracellular degradation were added to the model. Scan data from GEP-NET patients were used for evaluation of model predictions. Simulations with increasing tumor volumes were performed to assess the tumor sink effect.

RESULTS

Data of 39 and 59 patients receiving [⁶⁸Ga]Ga-DOTATATE and [⁶⁸Ga]Ga-HA-DOTATATE, respectively, were included. Evaluations showed that the model adequately described image-based patient data and that different receptor affinities caused organ uptake dissimilarities between both peptides. Sensitivity analysis indicated that tumor blood flow and blood volume impacted tumor distribution most. Tumor sink predictions showed a decrease in spleen uptake with increasing tumor volume, which seemed clinically relevant for patients with total tumor volumes higher than ~ 550 mL.

CONCLUSION

The developed PBPK model adequately predicted tumor and organ uptake for this GEP-NET population. Relevant organ uptake differences between [⁶⁸Ga]Ga-DOTATATE and [⁶⁸Ga]Ga-HA-DOTATATE were caused by different affinity profiles, while tumor uptake was mainly affected by tumor blood flow and blood volume. Furthermore, tumor sink predictions showed that for the majority of patients a tumor sink effect is not expected to be clinically relevant.

Know thy tumour: Biomarkers to improve treatment of molecular radionuclide therapy

Molecular radionuclide therapy (MRT) is an effective treatment for both localised and disseminated tumours. Biomarkers can be used to identify potential subtypes of tumours that are known to respond better to standard MRT protocols. These enrolment-based biomarkers can further be used to develop dose-response relationships using image-based dosimetry within these defined subtypes. However, the biological identity of the cancers treated with MRT are commonly not well-defined, particularly for neuroendocrine neoplasms. The biological heterogeneity of such cancers has hindered the establishment of dose-responses and minimum tumour dose thresholds. Biomarkers could also be used to determine normal tissue MRT dose limits and permit greater injected doses of MRT in patients. An alternative approach is to understand the repair capacity limits of tumours using radiobiology-based biomarkers within and outside patient cohorts currently treated with MRT. It is hoped that by knowing more about tumours and how they respond to MRT, biomarkers can provide needed dimensionality to image-based biodosimetry to improve MRT with optimized protocols and personalised therapies.

Peptide receptor radionuclide therapy (PRRT) in radioiodine-refractory thyroid cancer: A case report of significant response to lu177 DOTA-TATE treatment

A 59-year-old woman with follicular thyroid carcinoma underwent total thyroidectomy followed by radioiodine treatment. Following treatment, the whole-body scan did not show any abnormal radioiodine uptake. However, during the follow-up, the serum thyroglobulin (Tg) value increased without detectable thyroglobulin-antibodies. We performed a Ga-68 DOTA-TATE PET/CT showing a sternal lesion and several lung nodules with high somatostatin receptor density. Also, on the next day, FDG PET/CT was performed, which confirmed the findings. Considering the high levels of somatostatin receptor expression in such metastases, we planned lu177 DOTA-TATE therapy. After two cycles of lu177 DOTA-TATE injection, serum thyroglobulin significantly dropped, and she claimed that her sternal pain and dyspnea were much better. This was the case of a patient suffering from iodine-refractory follicular thyroid carcinoma, with somatostatin-receptor expression, treated with 177Lu-DOTA-TATE, showing a significant response.

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.

Towards an era of precise diagnosis and treatment: Role of novel molecular modification-based imaging and therapy for dedifferentiated thyroid cancer

Dedifferentiated thyroid cancer is the major cause of mortality in thyroid cancer and is difficult to treat. Hence, the essential molecular mechanisms involved in dedifferentiation should be thoroughly investigated. Several studies have explored the biomolecular modifications of dedifferentiated thyroid cancer such as DNA methylation, protein phosphorylation, acetylation, ubiquitination, and glycosylation and the new targets for radiological imaging and therapy in recent years. Novel radionuclide tracers and drugs have shown attractive potential in the early diagnosis and treatment of dedifferentiated thyroid cancer. We summarized the updated molecular mechanisms of dedifferentiation combined with early detection by molecular modification-based imaging to provide more accurate diagnosis and novel therapeutics in the management of dedifferentiated thyroid cancer.

Peptide Receptor Radionuclide Therapy in Thyroid Cancer

The treatment options that are currently available for management of metastatic, progressive radioactive iodine (RAI)-refractory differentiated thyroid cancers (DTCs), and medullary thyroid cancers (MTCs) are limited. While there are several systemic targeted therapies, such as tyrosine kinase inhibitors, that are being evaluated and implemented in the treatment of these cancers, such therapies are associated with serious, sometimes life-threatening, adverse events. Peptide receptor radionuclide therapy (PRRT) has the potential to be an effective and safe modality for treating patients with somatostatin receptor (SSTR)+ RAI-refractory DTCs and MTCs. MTCs and certain sub-types of RAI-refractory DTCs, such as Hürthle cell cancers which are less responsive to conventional modalities of treatment, have demonstrated a favorable response to treatment with PRRT. While the current literature offers hope for utilization of PRRT in thyroid cancer, several areas of this field remain to be investigated further, especially head-to-head comparisons with other systemic targeted therapies. In this review, we provide a comprehensive outlook on the current translational and clinical data on the use of various PRRTs, including diagnostic utility of somatostatin analogs, theranostic properties of PRRT, and the potential areas for future research.

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.

Imaging and liquid biopsy in the prediction and evaluation of response to PRRT in neuroendocrine tumors: implications for patient management

Purpose

The aim of this narrative review is to give an overview on current and emerging imaging methods and liquid biopsy for prediction and evaluation of response to PRRT. Current limitations and new perspectives, including artificial intelligence, are discussed.

Methods

A literature review of PubMed/Medline was performed with representative keywords. The search included articles published online through August 31, 2020. All searches were restricted to English language manuscripts.

Results

Peptide radio receptor therapy (PRRT) is a prospectively evaluated and approved therapy option in neuroendocrine tumors (NETs). Different ligands targeting the somatostatin receptor (SSTR) are used as theranostic pairs for imaging NET and for PRRT. Response assessment in prospective trials often relies on the morphological RECIST 1.1 criteria, based on lesion size in CT or MRI. The role of SSTR-PET and quantitative uptake parameters and volumetric data is still not defined. Monoanalyte tumor marker chromogranin A has a limited value for response assessment after PRRT. New emerging liquid biopsy techniques are offering prediction of response to PRRT and prognostic value.

Conclusions

New response criteria for NET patients undergoing PRRT will comprise multiparametric hybrid imaging and blood-based multianalyte markers. This represents tumor biology and heterogeneity.

177Lu-DOTA-EB-TATE, a Radiolabeled Analogue of Somatostatin Receptor Type 2, for the Imaging and Treatment of Thyroid Cancer

PURPOSE

The goal of this study was to analyze the role of somatostatin receptor type 2 (SSTR2) as a molecular target for the imaging and treatment of thyroid cancer through analysis of SSTR2 expression and its epigenetic modulation and testing tumor uptake of different radiolabeled SSTR2 analogues.

EXPERIMENTAL DESIGN

We analyzed SSTR2 expression by immunostaining of 92 thyroid cancer tissue samples and quantified standard uptake values (SUV_max) of SSTR2 analogue, ⁶⁸Ga-DOTA-TATE, by PET/CT imaging in 25 patients with metastatic thyroid cancer. We utilized human thyroid cancer cell lines characterized by differential SSTR2 expression (TT, BCPAP, and FTC133) and rat pancreatic cell line (AR42J) with intrinsically high SSTR2 expression for functional in vitro studies. SSTR2-high (AR42J) and SSTR2-low (FTC133) xenograft mouse models were used to test the uptake of radiolabeled SSTR2 analogues and their therapeutic efficacy in vivo.

RESULTS

Thyroid cancer had a higher SSTR2 expression than normal thyroid. Hurthle cell thyroid cancer was characterized by the highest ⁶⁸Ga-DOTA-TATE uptake [median SUV_max, 16.5 (7.9-29)] than other types of thyroid cancers. In vivo studies demonstrated that radiolabeled DOTA-EB-TATE is characterized by significantly higher tumor uptake than DOTA-TATE (P < 0.001) and DOTA-JR11 (P < 0.001). Treatment with ¹⁷⁷Lu-DOTA-EB-TATE extended survival and reduced tumor size in a mouse model characterized by high somatostatin (SST) analogues uptake (SUV_max, 15.16 ± 4.34), but had no effects in a model with low SST analogues uptake (SUV_max, 4.8 ± 0.27).

CONCLUSIONS

A novel SST analogue, ¹⁷⁷Lu-DOTA-EB-TATE, has the potential to be translated from bench to bedside for the targeted therapy of patients characterized by high uptake of SST analogues in metastatic lesions.

Updated Review of Nuclear Molecular Imaging of Thyroid Cancers

OBJECTIVES

We initiate this comprehensive review to update the advances in this field by objectively elucidating the efficacies of promising radiopharmaceuticals.

METHODS

We performed a comprehensive PUBMED search using the combined terms of "thyroid cancer" and "radiopharmaceuticals" or "nuclear medicine", yielding 3273 and 11026 articles prior to December 31, 2020, respectively.

RESULTS

Based on the mechanism of molecular metabolism, the evaluation of differentiated thyroid cancer and dedifferentiated thyroid cancer is largely centered around radioiodine and fluorine 18 (¹⁸F)-fludeoxyglucose, respectively. Further, ¹⁸F-L-dihydroxyphenylalanine and gallium 68 DOTATATE are the preferred tracers for medullary thyroid cancer. In dedifferentiated medullary thyroid cancer and anaplastic thyroid cancer, ¹⁸F-fludeoxyglucose is superior.

CONCLUSIONS

The future lies in advances in molecular biology, novel radiopharmaceuticals and imaging devices, paving ways to the development of personalized medication for thyroid cancer patients.

Radioactive Iodine Therapy in Differentiated Thyroid Cancer: 2020 Update

OBJECTIVE. The paradigm of theranostics is based on tailoring therapy for the purpose of optimizing outcomes. This principle is being applied to radioactive iodine therapy. Consequently, thyroid cancer therapy protocols are evolving. The purpose of this article is to promote a modern approach to radioiodine therapy. CONCLUSION. This article highlights guidelines and position statements, summarizes the prognostication systems of thyroid cancer, and reviews which prescribed activities of ¹³¹I.

Peptide Receptor Radionuclide Therapy in Patients With Differentiated Thyroid Cancer: A Meta-analysis

PURPOSE

As patients with progressive medullary thyroid cancer (MTC) and radioiodine-refractory metastatic differentiated nonmedullary thyroid cancer (DTC) have poor prognoses and present therapeutic challenges, peptide receptor radionuclide therapy (PRRT) targeting the somatostatin receptor provides a promising option. This meta-analysis evaluated the therapeutic effects and outcomes of PRRT in differentiated thyroid cancer.

PATIENTS AND METHODS

PUBMED, EMBASE, CINAHL, SCOPUS, and COCHRANE were systematically searched using appropriate key words. The primary therapeutic effect was the radiological response after PRRT, and the objective response rate (ORR) and disease control rate (DCR) were identified in MTC and DTC, respectively. The outcome of serious adverse events (grade 3 or 4), additional therapeutic effects of F-FDG PET/CT and biochemical (calcitonin and thyroglobulin) responses, and radionuclides for PRRT were assessed as subgroup analyses. The parameters were generated as pooled proportions.

RESULTS

Eleven articles with 165 patients were included (98 patients with MTC and 67 patients with DTC). PRRT achieved pooled proportions of ORR in 8.53% to 15.61%, DCR in 53.95% to 59.99%, and serious adverse events in 2.79% to 2.82% in MTC and DTC patients. F-FDG PET/CT and biochemical responses revealed similar results as the radiological response. Lu-based PRRT (ORR, 11.48%-24.52%; DCR, 61.47%-67.26%) showed better therapeutic effects than Y-based PRRT (ORR, 6.98%-13.82%; DCR, 50.86%-57.29%).

CONCLUSIONS

This meta-analysis suggests that PRRT could be a potential and safe strategy for MTC and DTC. In particular, PRRT with Lu exhibited improved therapeutic effects relative to PRRT with Y.

177Lu-DOTATATE and 177Lu-prostate-specific membrane antigen therapy in a patient with advanced metastatic radioiodine-refractory differentiated thyroid cancer after failure of tyrosine kinase inhibitors treatment

Patients with radioiodine-refractory differentiated thyroid cancer (RrDTC) have only a limited or no benefit from radioiodine therapy. For these patients, tyrosine kinase inhibitors have demonstrated encouraging results in advanced RrDTC. Nevertheless, these therapies are related with substantial side effects and a high cost. Somatostatin receptor-based therapies have shown promising findings in advanced RrDTC. Recently, prostate-specific membrane antigen (PSMA) expression was seen in advanced RrDTC in imaging studies. This study presents a case of RrDTC who was treated with ¹⁷⁷Lu-DOTATATE and ¹⁷⁷Lu-PSMA, presumably as a first report in this regard.