Targeting Integrins with Radiolabeled RGD Analogues for Radiotheranostics of Metastatic Radioactive Iodine Nonresponsive Thyroid Cancer: New Avenues in Personalized Medicine

Advances in the Development of Positron Emission Tomography Tracers for Improved Detection of Differentiated Thyroid Cancer

Thyroid cancer poses a significant challenge in clinical management, necessitating precise diagnostic tools and treatment strategies for optimal patient outcomes. This review explores the evolving field of radiotracers in the diagnosis and management of thyroid cancer, focusing on prostate-specific membrane antigen (PSMA)-based radiotracers, fibroblast activation protein inhibitor (FAPI)-based radiotracers, Arg-Gly-Asp (RGD)-based radiotracers, and 18F-tetrafluoroborate (18F-TFB). PSMA-based radiotracers, initially developed for prostate cancer imaging, have shown promise in detecting thyroid cancer lesions; however, their detection rate is lower than 18F-FDG PET/CT. FAPI-based radiotracers, targeting fibroblast activation protein highly expressed in tumors, offer potential in the detection of lymph nodes and radioiodine-resistant metastases. RGD-based radiotracers, binding to integrin αvβ3 found on tumor cells and angiogenic blood vessels, demonstrate diagnostic accuracy in detecting radioiodine-resistant thyroid cancer metastases. 18F-TFB emerges as a promising PET tracer for imaging of lymph node metastases and recurrent DTC, offering advantages over traditional methods. Overall, these radiotracers show promise in enhancing diagnostic accuracy, patient stratification, and treatment selection in differentiated thyroid cancer, warranting further research and clinical validation. Given the promising staging capabilities of 18F-TFB and the efficacy of FAP-targeting tracers in advanced, potentially dedifferentiated cases, continued investigation in these domains is justified.

Evaluation of integrin αvβ3-targeted imaging for predicting disease progression in patients with high-risk differentiated thyroid cancer (using 99mTc-3PRGD2)

BACKGROUND

High-risk differentiated thyroid cancer (DTC) needs effective early prediction tools to improving clinical management and prognosis. This cohort study aimed to investigate the prognostic impact of ^99mTc-PEG₄-E[PEG₄-c(RGDfK)]₂ (^99mTc-3PRGD₂) SPECT/CT in high-risk DTC patients after initial radioactive iodine (RAI) therapy.

METHODS

Thirty-three patients with high-risk DTC were prospectively recruited; all patients underwent total thyroidectomy and received ^99mTc-3PRGD₂ SPECT/CT before RAI ablation. Follow-up was done with serological and imaging studies. The correlation between ^99mTc-3PRGD₂ avidity and remission rate for initial RAI therapy was evaluated using logistic regression analysis. The prognostic value of ^99mTc-3PRGD₂ SPECT/CT was evaluated by Kaplan-Meier curve and Cox regression analysis.

RESULTS

^99mTc-3PRGD₂ avidity was significantly correlated with the efficacy of initial RAI ablation and an effective predictor for non-remission in high-risk DTC (OR = 9.36; 95% CI = 1.10-79.83; P = 0.041). ^99mTc-3PRGD₂ avidity was associated with poor prognosis in patients with high-risk DTC and an independent prognostic factor for shorter progression-free survival (PFS) (HR = 9.47; 95% CI = 1.08-83.20; P = 0.043). Survival analysis, which was performed between DTC patients with concordant (¹³¹I positive/^99mTc-3PRGD₂ positive) and discordant (¹³¹I negative/^99mTc-3PRGD₂ positive) lesions, indicated that patients with concordant lesions had significantly better PFS than those with discordant lesions (P = 0.022). Moreover, compared with repeated RAI, additional surgery or targeted therapy with multikinase inhibitors could lead to a higher rate of remission in ^99mTc-3PRGD₂-positive patients with progressive disease.

CONCLUSIONS

^99mTc-3PRGD₂ SPECT/CT is a useful modality in predicting progression of the disease after initial RAI and guiding further treatment in high-risk DTC patients.

Radiometal-theranostics: the first 20 years*

This review describes the basic principles of radiometal-theranostics and its dawn based on the development of the positron-emitting 86Y and 86Y-labeled radiopharmaceuticals to quantify biodistribution and dosimetry of 90Y-labeled analogue therapeutics. The nuclear and inorganic development of 86Y (including nuclear and cross section data, irradiation, radiochemical separation and recovery) led to preclinical and clinical evaluation of 86Y-labeled citrate and EDTMP complexes and yielded organ radiation doses in terms of mGy/MBq 90Y. The approach was extended to [86/90Y]Y-DOTA-TOC, yielding again yielded organ radiation doses in terms of mGy/MBq 90Y. The review further discusses the consequences of this early development in terms of further radiometals that were used (68Ga, 177Lu etc.), more chelators that were developed, new biological targets that were addressed (SSTR, PSMA, FAP, etc.) and subsequent generations of radiometal-theranostics that resulted out of that.

Investigation of the Presence of Integrin Alpha-3 and Beta-1 Receptors on Tumor Tissue, Metastatic Lymph Node and Normal Tissue in Thyroid Cancer

Objectives:

The important roles of integrins in tumor invasion, migration and proliferation are well known. In this study, we investigated the presence of integrin α3 and β1 receptors in tumor tissue, metastatic lymph node (LN) and normal thyroid tissue of patients diagnosed with thyroid cancer (TCa) and showed the prognostic and diagnostic value of these molecules as well as peptide-receptor.

Methods:

Sixty-one patients with TCa were included in this study. The presence of integrin α3 and β1 expression was investigated by immunohistochemical methods from tumor tissue after total thyroidectomy. TNM system was used in tumor staging. The relationship between prognostic properties such as tumor size, LN metastasis, capsular invasion and the presence of integrin α3 and β1 expression was investigated.

Results:

Classical type papillary TCa was the most common subtype in our study group with 31.1%. Integrin β1 was expressed in 4.9% (n=3) of normal tissue, 57.4% (n=35) of tumor tissue and 16.4% (n=10) of metastatic LN; integrin α3 was expressed in 50.8% (n=31) of normal tissue, 67.2% (n=41) of tumor tissue and 9.8% (n=6) metastatic LN. Integrin β1 expression was observed 21.3% (n=13), integrin α3 in 14.8% (n=9) and integrin α3 and β1 expression in 36.1% (n=22). Integrin β1 expression increased statistically significantly in the presence of LN metastasis and capsular invasion (p=0.022, 0.014, respectively). Furthermore, the expression of integrin α3 was found to be statistically significant in primary tumors of patients with LN metastasis (p=0.045).

Conclusion:

Our study showed a significant increase in integrin α3 and β1 expression in LN metastasis or thyroid capsule invasion in tumor. Thus, it appears that the demonstration of the presence of integrin α3 and β1 expression in TCa is not only a prognostic biomarker but also has value as a potential theranostic target with peptide-bound radioactive agents.

Translating Molecules into Imaging—The Development of New PET Tracers for Patients with Melanoma

Melanoma is a deadly disease that often exhibits relentless progression and can have both early and late metastases. Recent advances in immunotherapy and targeted therapy have dramatically increased patient survival for patients with melanoma. Similar advances in molecular targeted PET imaging can identify molecular pathways that promote disease progression and therefore offer physiological information. Thus, they can be used to assess prognosis, tumor heterogeneity, and identify instances of treatment failure. Numerous agents tested preclinically and clinically demonstrate promising results with high tumor-to-background ratios in both primary and metastatic melanoma tumors. Here, we detail the development and testing of multiple molecular targeted PET-imaging agents, including agents for general oncological imaging and those specifically for PET imaging of melanoma. Of the numerous radiopharmaceuticals evaluated for this purpose, several have made it to clinical trials and showed promising results. Ultimately, these agents may become the standard of care for melanoma imaging if they are able to demonstrate micrometastatic disease and thus provide more accurate information for staging. Furthermore, these agents provide a more accurate way to monitor response to therapy. Patients will be able to receive treatment based on tumor uptake characteristics and may be able to be treated earlier for lesions that with traditional imaging would be subclinical, overall leading to improved outcomes for patients.

Multimodal Imaging of Target Detection Algorithm under Artificial Intelligence in the Diagnosis of Early Breast Cancer

This study aimed to analyze the diagnostic value of multimodal images based on artificial intelligence target detection algorithms for early breast cancer, so as to provide help for clinical imaging examinations of breast cancer. This article combined residual block with inception block, constructed a new target detection algorithm to detect breast lumps, used deep convolutional neural network and ultrasound imaging in diagnosing benign and malignant breast lumps, took breast density grading with mammography, compared the convolutional neural network (CNN) algorithm with the proposed algorithm, and then applied the proposed algorithm to the diagnosis of 120 female patients with breast lumps. According to the results, accuracy rates of breast lump detection (94.76%), benign and malignant breast lumps diagnosis (98.22%), and breast grading (93.65%) with the algorithm applied in this study were significantly higher than those (75.67%, 87.23%, and 79.54%) with CNN algorithm, and the difference was statistically significant (P < 0.05); among 62 patients with malignant breast lumps of the 120 patients with breast lumps, 37 were patients with invasive ductal carcinoma, 8 with lobular carcinoma in situ, 16 with intraductal carcinoma, and 4 with mucinous carcinoma; among the remaining 58 patients with benign breast lumps, 28 were patients with fibrocystic breast disease, 17 with intraductal papilloma, 4 with breast hyperplasia, and 9 with adenopathy; the differences in shape, growth direction, edge, and internal echo of multimodal ultrasound imaging of patients with benign and malignant breast lumps had statistical significance (P < 0.05); the malignant constituent ratios of patients with breast density grades I to IV were 0%, 7.10%, 80.40%, and 100%, respectively. In short, the multimodal imaging diagnosis under the algorithm in this article was superior to CNN algorithm in all aspects; according to the judgment on benign and malignant breast lumps and breast density with multimodal imaging features, the higher the breast density, the higher the probability of breast cancer.

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.

Non-Cationic RGD-Containing Protein Nanocarrier for Tumor-Targeted siRNA Delivery

Despite the recent successes in siRNA therapeutics, targeted delivery beyond the liver remains the major hurdle for the widespread application of siRNA in vivo. Current cationic liposome or polymer-based delivery agents are restricted to the liver and suffer from off-target effects, poor clearance, low serum stability, and high toxicity. In this study, we genetically engineered a non-cationic non-viral tumor-targeted universal siRNA nanocarrier (MW 26 KDa). This protein nanocarrier consists of three function domains: a dsRNA binding domain (dsRBD) (from human protein kinase R) for any siRNA binding, 18-histidine for endosome escape, and two RGD peptides at the N- and C-termini for targeting tumor and tumor neovasculature. We showed that cloned dual-RGD-dsRBD-18his (dual-RGD) protein protects siRNA against RNases, induces effective siRNA endosomal escape, specifically targets integrin α_vβ₃ expressing cells in vitro, and homes siRNA to tumors in vivo. The delivered siRNA leads to target gene knockdown in the cell lines and tumor xenografts with low toxicity. This multifunctional and biomimetic siRNA carrier is biodegradable, has low toxicity, is suitable for mass production by fermentation, and is serum stable, holding great potential to provide a widely applicable siRNA carrier for tumor-targeted siRNA delivery.

Bioinspired peptide adhesion on Ti implants alleviates wear particle-induced inflammation and improves interfacial osteogenesis

In the inflammatory peri-implant microenvironment, excessive polarization of macrophages to the proinflammatory M1 phenotype can trigger the secretion of inflammatory cytokines, which promote bone resorption and impede osteogenesis around implants. The direct consequence of this process is the failure of prosthetic implants due to aseptic loosening. To reverse the inflammatory microenvironment and prevent prosthesis loosening, a mussel adhesion-inspired surface strategy was used for bioengineering of titanium implants with integrin-binding ability. In our design, a mussel-inspired catecholic peptide with tetravalent 3,4-dihydroxy-l-phenylalanine (DOPA) and Arg-Gly-Asp (RGD) sequences was synthesized. The peptide can easily anchor to the surface of medical titanium materials through a mussel adhesive mechanism. We found that peptide-decorated titanium implants could effectively inhibit peri-implant inflammation in a wear particle model and could promote the polarization of macrophages to a pro-healing M2 phenotype by interfering with integrin-α₂β₁ and integrin-α_vβ₃. Moreover, the peptide coating increased the adherence of osteoblasts and promoted osteogenesis on titanium implants even under inflammatory conditions. This work suggested that this biomimetic catecholic integrin-binding peptide can provide facile tactics for surface bioengineering of medical prostheses with improved interfacial osteogenesis under inflammatory conditions, which might contribute greatly to the prevention of prosthesis loosening and the improvement of clinical outcomes.

IVUS\IVPA hybrid intravascular molecular imaging of angiogenesis in atherosclerotic plaques via RGDfk peptide-targeted nanoprobes

Current intravascular imaging modalities face hurdles in the molecular evaluation of progressed plaques. This study aims to construct a novel hybrid imaging system (intravascular ultrasound/intravascular photoacoustic, IVPA/IVUS) via RGDfk peptide-targeted nanoparticles for monitoring angiogenesis in progressed atherosclerotic plaques in a rabbit model. An atherosclerotic rabbit model was induced by abdominal aorta balloon de-endothelialization followed by a high-fat diet. A human serum albumin (HSA)-based nanoprobe modified with RGDfk peptide was constructed by encapsulating indocyanine green (ICG) via electrostatic force (ICG-HSA-RGDfk NPs, IHR-NPs). A hybrid intravascular imaging system that combined IVUS and IVPA was self-assembled for RGDfk visualization within atherosclerotic plaques in the rabbit abdominal aorta. Through IHR-NPs and the hybrid IVUS/IVPA imaging platform, multiple comprehensive pieces of information on progressed plaques, including anatomical information, composition information and molecular information, can be obtained simultaneously, which may improve the precise diagnosis of plaque characteristics and the evaluation of early interventions for atherosclerosis.