(68)Ga-DOTA-peptide: A novel molecular biomarker for nasopharyngeal carcinoma

A head-to-head comparison of [68Ga]Ga-DOTATATE and [68Ga]Ga-FAPI PET/CT in patients with nasopharyngeal carcinoma: a single-center, prospective study

PURPOSE

We aimed to compare the staging efficiency of [68Ga]Ga-DOTATATE and [68Ga]Ga-FAPI PET/CT in nasopharyngeal carcinoma (NPC) patients.

METHODS

Thirty-nine patients with pathologically confirmed NPC were enrolled in this prospective study. Each patient underwent paired [68Ga]Ga-DOTATATE and [68Ga]Ga-FAPI PET/CT on 2 successive days. The accuracy of two PET/CT for assessing T, N, and M stages was compared by using head-and-neck MRI, histopathologic diagnosis and follow-up results as reference standards. The radiotracer uptake derived from two PETs was also compared.

RESULTS

For treatment-naïve patients, [68Ga]Ga-DOTATATE PET/CT showed identical sensitivity for the primary tumours but clearer tumor delineation induced by higher tumour-to-background (TBR) ratio (19.1 ± 8.7 vs. 12.4 ± 7.7, P = 0.003), compared with [68Ga]Ga-FAPI PET/CT. Regarding cervical lymph node (CLN) metastases, [68Ga]Ga-DOTATATE PET had significantly better sensitivity and accuracy based on neck sides (98% vs. 82%, P < 0.001; 99% vs. 88% P = 0.008), neck levels (98% vs. 78%, 99% vs. 97%; both P < 0.001) and individual nodes (89% vs. 56%, 91% vs. 76%; both P < 0.001), and higher TBR (8.1 ± 4.1 vs. 6.3 ± 3.7, P < 0.001). Additionally, [68Ga]Ga-DOTATATE PET/CT revealed higher sensitivity and accuracy for distant metastases (96% vs. 53%, 95% vs. 52%; both P < 0.001), particularly in bone metastases (99% vs. 49%, 97% vs. 49%; both P < 0.001). For post-treatment patients, [68Ga]Ga-DOTATATE PET/CT identified one more true-negative case than [68Ga]Ga-FAPI PET/CT.

CONCLUSION

[68Ga]Ga-DOTATATE PET/CT performed better than [68Ga]Ga-FAPI PET/CT in visualizing the primary tumours, detecting the metastatic lesions and identifying the local recurrence, suggesting [68Ga]Ga-DOTATATE PET/CT may be superior to [68Ga]Ga-FAPI PET/CT for NPC staging.

A case of metastatic lymphoepithelial carcinoma of parotid gland identified on 68gallium DOTA-[Tyr3] octreotate PET CT

The authors present the case of a 59-year-old lady diagnosed with lymphoepithelial carcinoma (LEC) of the left parotid gland. The primary tumour was identified using contrast-enhanced CT, and diagnosis was confirmed via fine needle aspiration cytology and immunohistochemistry. Staging using fluorine-18 fluorodeoxyglucose PET CT revealed regional nodal metastases, while no distant metastasis was evident. Following radical radiotherapy, a favourable locoregional response was observed on MRI, yet the patient's plasma Epstein-Barr virus load continued to rise. Given her primary tumour's somatostatin receptor type 2 (SSTR2) positivity, gallium-68 DOTA-[Tyr3] octreotate PET CT (68Ga-DOTATATE PET CT) was performed, revealing multiple distant metastases with DOTATATE avidity. Despite attempts at palliative chemotherapy and immunotherapy, disease progression led to the decision for the best supportive care. The unique presentation of metastatic LEC on 68Ga-DOTATATE PET CT suggests a potential role for SSTR2-targeted imaging in diagnosis and management.

18 F-fludeoxyglucose positron emission computed tomography (18 F-FDG-PET/CT) versus 68 Ga-DOTATATE-PET/CT in patients with head and neck cancer: Comparisons and implications for treatment

BACKGROUND

Tumor-specific molecular imaging in head and neck squamous cell carcinoma (HNSCC) is not well established. Somatostatin receptors (SSTRs) are found in solid tumors, including HNSCC. ⁶⁸ Ga-DOTATATE, a commercially available radionuclide that binds SSTRs, may have utility in imaging HNSCC.

METHODS

Patients with HNSCC received pretreatment imaging with ¹⁸ F-FDG-PET/CT and ⁶⁸ Ga-DOTATATE. Imaging was compared for concordance. When available, surgical resection specimens were compared to pretreatment imaging findings. Historic HNSCC tumor specimens were assessed for both SSTR and p16/human papilloma virus (HPV) expression.

RESULTS

Twenty patients were imaged. Fifteen had oropharyngeal cancer. Primary tumor site was concordant between imaging modalities for all patients. One of 45 lymph nodes was discordant. Retrospective specimen review showed a significant correlation with SSTR expression and HPV/p16 expression. No adverse events occurred.

CONCLUSIONS

⁶⁸ Ga-DOTATATE imaging is safe and effective in HNSCC. SSTR expression may be increased in HPV-mediated tumors. Targeted therapies to SSTR should be explored.

Advances in nuclear medicine-based molecular imaging in head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCCs) are often aggressive, making advanced disease very difficult to treat using contemporary modalities, such as surgery, radiation therapy, and chemotherapy. However, targeted therapy, e.g., cetuximab, an epidermal growth factor receptor inhibitor, has demonstrated survival benefit in HNSCC patients with locoregional failure or distant metastasis. Molecular imaging aims at various biomarkers used in targeted therapy, and nuclear medicine-based molecular imaging is a real-time and non-invasive modality with the potential to identify tumor in an earlier and more treatable stage, before anatomic-based imaging reveals diseases. The objective of this comprehensive review is to summarize recent advances in nuclear medicine-based molecular imaging for HNSCC focusing on several commonly radiolabeled biomarkers. The preclinical and clinical applications of these candidate imaging strategies are divided into three categories: those targeting tumor cells, tumor microenvironment, and tumor angiogenesis. This review endeavors to expand the knowledge of molecular biology of HNSCC and help realizing diagnostic potential of molecular imaging in clinical nuclear medicine.

Somatostatin receptor imaging with [68Ga]Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma

PURPOSE

To explore the feasibility of [⁶⁸Ga]Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) in patients with non-keratinizing nasopharyngeal carcinoma (NPC) and to evaluate whether [⁶⁸Ga]Ga-DOTATATE PET/CT could be used for non-invasive determination of somatostatin receptor 2 (SSTR2) expression in NPC.

METHODS

This prospective study included patients with NPC who underwent [⁶⁸Ga]Ga-DOTATATE PET/CT between February and May 2021. The [⁶⁸Ga]Ga-DOTATATE and [¹⁸F]FDG uptakes in primary and metastatic NPC lesions were calculated and compared, and the [⁶⁸Ga]Ga-DOTATATE uptake between SSTR2 score groups was analysed.

RESULTS

A total of 36 participants (25 patients, initial staging; 11 patients, recurrence detection) were included; 33 patients also underwent [¹⁸F]FDG PET/CT for staging/restaging as a part of their routine diagnostic workup. [⁶⁸Ga]Ga-DOTATATE PET/CT showed an intense tracer uptake in primary and metastatic NPC lesions. The radiotracer uptake was higher with [⁶⁸Ga]Ga-DOTATATE than with [¹⁸F]FDG PET in primary NPC lesions (SUVmax: 12.03 vs. 10.07, P = 0.048; tumour-to-brain ratio: 36.16 vs. 0.86, P < 0.001) and regional lymph node metastases (median SUVmax: 9.11 vs. 6.12, P < 0.001) and comparable in bone and visceral metastases. Importantly, most NPC lesions showed intense SSTR2 expression (85.7%), which was strongly correlated with the [⁶⁸Ga]Ga-DOTATATE uptake. The SUVmax of SSTR2-negative lesions was significantly lower than that of SSTR2-positive lesions (SUVmax: 4.95 vs. 12.61, P = 0.013).

CONCLUSION

[⁶⁸Ga]Ga-DOTATATE PET/CT is a promising imaging modality for detecting primary and metastatic NPC, with favourable image contrast and comparable diagnostic efficacy when compared to [¹⁸F]FDG PET/CT. An intense SSTR2 expression was observed in most NPCs, and this expression was significantly correlated with the [⁶⁸Ga]Ga-DOTATATE uptake.

SSTR2 in Nasopharyngeal Carcinoma: Relationship with Latent EBV Infection and Potential as a Therapeutic Target

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor, most commonly located in the pharyngeal recess and endemic to parts of Asia. It is often detected at a late stage which is associated with poor prognosis (5-year survival rate of 63%). Treatment for this malignancy relies predominantly on radiotherapy and/or systemic chemotherapy, which can be associated with significant morbidity and impaired quality of life. In endemic regions NPC is associated with infection by Epstein-Barr virus (EBV) which was shown to upregulate the somatostatin receptor 2 (SSTR2) cell surface receptor. With recent advances in molecular techniques allowing for an improved understanding of the molecular aetiology of this disease and its relation to SSTR2 expression, we provide a comprehensive and up-to-date overview of this disease and highlight the emergence of SSTR2 as a key tumor biomarker and promising target for imaging and therapy.

Somatostatin receptor 2 expression in nasopharyngeal cancer is induced by Epstein Barr virus infection: impact on prognosis, imaging and therapy

Nasopharyngeal cancer (NPC), endemic in Southeast Asia, lacks effective diagnostic and therapeutic strategies. Even in high-income countries the 5-year survival rate for stage IV NPC is less than 40%. Here we report high somatostatin receptor 2 (SSTR2) expression in multiple clinical cohorts comprising 402 primary, locally recurrent and metastatic NPCs. We show that SSTR2 expression is induced by the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) via the NF-κB pathway. Using cell-based and preclinical rodent models, we demonstrate the therapeutic potential of SSTR2 targeting using a cytotoxic drug conjugate, PEN-221, which is found to be superior to FDA-approved SSTR2-binding cytostatic agents. Furthermore, we reveal significant correlation of SSTR expression with increased rates of survival and report in vivo uptake of the SSTR2-binding 68Ga-DOTA-peptide radioconjugate in PET-CT scanning in a clinical trial of NPC patients (NCT03670342). These findings reveal a key role in EBV-associated NPC for SSTR2 in infection, imaging, targeted therapy and survival.

SSTR2a is constantly expressed in lymphoepithelioma-like carcinoma with squamous differentiation other than that with glandular differentiation

AIMS

Somatostatin receptor 2a (SSTR2a) is an important diagnostic marker of meningioma and neuroendocrine tumours and is frequently expressed in primary and metastatic non-keratinising nasopharyngeal carcinoma (NK-NPC). Since NK-NPC cases are considered a kind of lymphoepithelioma-like carcinoma (LELCs) which originate from the nasopharynx, information on the expression profile of SSTR2a in LELC in other sites with squamous and glandular differentiations is still lacking. This study aimed to assess the expression of SSTR2a in LELC of various organs and clarify its expression profile.

METHODS

Expression of SSTR2a in 164 cases of LELC was retrospectively analysed by immunohistochemistry in paraffin-embedded tissues, including 146 cases of LELC with squamous differentiation (120 cases of the nasopharynx, 21 cases of the lung and 5 cases of the parotid gland) and 18 cases of LELC with glandular differentiation (15 cases of the stomach and 3 cases of the liver).

RESULTS

We found that all (100%) cases of LELC of the lung (21/21) and parotid gland (5/5), and 93.3% (112/120) cases of LELC of the nasopharynx showed a diffused and strong expression of SSTR2a, while cases of gastric (0/15) and biliary (0/3) showed no SSTR2a expression.

CONCLUSION

SSTR2a is constantly expressed in LELC with squamous differentiation, but not expressed in LELC with glandular differentiation. However, the selective expression mechanism of SSTR2a remains unknown, which needs further investigation. Our novel findings might provide potential therapeutic approaches for the treatment of LELC with squamous cell differentiation.

Role of Non-FDG-PET/CT in Head and Neck Cancer

Head and neck cancers are commonly encountered malignancies in the United States, of which the majority are attributed to squamous cell carcinoma. ¹⁸F-FDG-PET/CT has been well established in the evaluation, treatment planning, prognostic implications of these tumors and is routinely applied for the management of patients with these cancers. Many alternative investigational PET radiotracers have been extensively studied in the evaluation of these tumors. Although these radiotracers have not been able to replace ¹⁸F-FDG-PET/CT in routine clinical practice currently, they may provide important additional information about the biological mechanisms of these tumors, such as foci of tumor hypoxia as seen on hypoxia specific PET radiotracers such as ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO), which could be useful in targeting radioresistant hypoxic tumor foci when treatment planning. There are multiple other hypoxia-specific PET radiotracers such as ¹⁸F-Fluoroazomycinarabinoside (FAZA), ¹⁸F-Flortanidazole (HX4), which have been evaluated similarly, of which ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO) has been the most investigated. Other radiotracers frequently studied in the evaluation of these tumors include radiolabeled amino acid PET radiotracers, which show increased uptake in tumor cells with limited uptake in inflammatory tissue, which can be useful especially in differentiating postradiation inflammation from residual and/or recurrent disease. ¹⁸F-Fluorothymidine (FLT) is localized intracellularly by nucleoside transport and undergoes phosphorylation thereby being retained within tumor cells and can serve as an indicator of tumor proliferation. Decrease in radiotracer activity following treatment can be an early indicator of treatment response. This review aims at synthesizing the available literature on the most studied non-FDG-PET/CT in head and neck cancer.

Expression of potential therapeutic target SSTR2a in primary and metastatic non-keratinizing nasopharyngeal carcinoma

Somatostatin receptor 2a (SSTR2a) is an important diagnostic and scintigraphic marker in several tumors, as well as a potential therapeutic target. However, the expression and clinicopathologic significance of SSTR2a in nasopharyngeal carcinoma (NPC) remain unknown. The expression of SSTR2a was retrospectively analyzed in a large series of NPC tissue samples (106 primary NPC samples, comprising 99 primary non-keratinizing NPC (NK-NPC) and 7 keratinizing NPC (K-NPC) samples, and 41 metastatic NPC samples) by immunohistochemistry, with 24 cases of normal nasopharyngeal mucosa tissues used as a control group. Normal epithelia in nasopharyngeal mucosa were negative for SSTR2a in all 24 cases. The expression of SSTR2a in primary NPC was correlated to the histological subtype. Most cases of primary NK-NPC showed expression of SSTR2a (93.9%, 93/99 cases). The percentage of SSTR2a-positive tumor cells ranged from 10 to 100%, while the intensity ranged from 2+ to 4+. None of the primary K-NPC samples showed SSTR2a expression (0/7, 100%). All cases of NPC showed negative expression of other neuroendocrine markers, including synaptophysin, chromogranin A, and CD56. Of all 41 cases of metastatic NK-NPC lesions, SSTR2a expression is concordant with that of the primary lesions, which shows statistical significance (p < 0.001). Our observations expand the spectrum of recognized SSTR2a-positive tumors and demonstrate for the first time that SSTR2a is frequently expressed in primary and metastatic NK-NPC, highlighting its potential as a scintigraphic and therapeutic target in this disease.

Recent advances of PET imaging in clinical radiation oncology

Radiotherapy and radiation oncology play a key role in the clinical management of patients suffering from oncological diseases. In clinical routine, anatomic imaging such as contrast-enhanced CT and MRI are widely available and are usually used to improve the target volume delineation for subsequent radiotherapy. Moreover, these modalities are also used for treatment monitoring after radiotherapy. However, some diagnostic questions cannot be sufficiently addressed by the mere use standard morphological imaging. Therefore, positron emission tomography (PET) imaging gains increasing clinical significance in the management of oncological patients undergoing radiotherapy, as PET allows the visualization and quantification of tumoral features on a molecular level beyond the mere morphological extent shown by conventional imaging, such as tumor metabolism or receptor expression. The tumor metabolism or receptor expression information derived from PET can be used as tool for visualization of tumor extent, for assessing response during and after therapy, for prediction of patterns of failure and for definition of the volume in need of dose-escalation. This review focuses on recent and current advances of PET imaging within the field of clinical radiotherapy / radiation oncology in several oncological entities (neuro-oncology, head & neck cancer, lung cancer, gastrointestinal tumors and prostate cancer) with particular emphasis on radiotherapy planning, response assessment after radiotherapy and prognostication.

2019 FDA TIDES (Peptides and Oligonucleotides) Harvest

2019 has been an excellent year in terms of peptides and oligonucleotides (TIDES) approved by the FDA. Despite the drop in the number of total drugs approved by the FDA in 2019 in comparison with 2018 (48 vs. 59), the total number of TIDES authorized increased (seven vs. three). Year after year, TIDES are increasingly present in therapy, as imaging agents, theragnostic and constituent moieties of other complex drugs, such as antibody drug conjugates. This means a consolidation of these kinds of drugs in the pharmaceutical arena, paving the way in the coming years for the approval of others for diverse medical indications. Here the TIDES approved in 2019 are analyzed in terms of chemical structure, medical target, mode of action, and adverse effects.

Metastatic Nasopharyngeal Carcinoma Treated With Intraarterial Combined With Intravenous Peptide Receptor Radionuclide Therapy

Nasopharyngeal carcinoma may express somatostatin receptors (SSTR). We present a case with metastatic nasopharyngeal carcinoma in the liver, bone, and lymph nodes. The patient was in progression after chemotherapy, external beam radiation therapy (ERBT), atezolizumab, and cetuximab. Due to strong SSTR expression of the metastases, PRRT was applied. After 3 cycles of intravenous Lu-DOTATOC and 1 cycle of intraarterial Y-DOTATOC therapy, the hepatic and bone metastases showed excellent response after PRRT. No nephrotoxicity or myelotoxicity was observed.

18F-Fluorodeoxyglucose-positron Emission Tomography/Computed Tomography Imaging of Metastatic Nasopharyngeal Cancer with Emphasis on the Distribution of Bone Metastases

Distant metastases change the prognosis of patients with nasopharyngeal carcinoma (NPC) which most commonly metastasizes to the bone. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is reported as useful in imaging NPC metastases. Our study assesses the incidence and distribution of bone metastases detected by ¹⁸F-FDG PET/CT in NPC. 717 ¹⁸F-FDG PET/CT scan reports of histologically proven NPC patients imaged in Singapore General Hospital, Singapore, between 2003 and 2009 were reviewed for the total number of metastases (scanned from vertex to mid-thigh) and analyzed for distribution. Of the 709 FDG avid metastases in these reports, 357/709 (50.35%) were locoregional nodal metastasis and 352/709 (49.65%) were distant metastases of which 192/709 (27.08%) of total metastases and 54.54% of distant metastases (192/352) were in the bones. The majority of the bone lesions 125/192 (65.1%) were in the axial skeleton with 109/192 (56.77%) in the lower skeleton (thoracolumbar spine, sacrum, and pelvis). The incidence of bone metastases in our study (27.08%) was higher than that reported in other studies, for example, 15% by Liu et al. and 11% (230 patients) by Caglar et al. Bone metastases have been reported in the femurs and the feet and as such some metastases may have been outside the field of view of the scans. In our study, 27% of FDG avid NPC metastases are in the bones.