Neuroradiological and Neuropathological Changes After 177Lu-Octreotate Peptide Receptor Radionuclide Therapy of Refractory Esthesioneuroblastoma

PET/CT Imaging in Treatment Planning and Surveillance of Sinonasal Neoplasms

Sinonasal cancers are uncommon malignancies with a generally unfavorable prognosis, often presenting at an advanced stage. Their high rate of recurrence supports close imaging surveillance and the utilization of functional imaging techniques. Whole-body 18F-FDG PET/CT has very high sensitivity for the diagnosis of sinonasal malignancies and can also be used as a "metabolic biopsy" in the characterization of some of the more common subgroups of these tumors, though due to overlap in uptake, histological confirmation is still needed. For certain tumor types, radiotracers, such as 11C-choline, and radiolabeled somatostatin analogs, including 68Ga-DOTATATE/DOTATOC, have proven useful in treatment planning and surveillance. Although serial scans for posttreatment surveillance allow the detection of subclinical lesions, the optimal schedule and efficacy in terms of survival are yet to be determined. Pitfalls of 18F-FDG, such as post-surgical and post-radiotherapy crusting and inflammation, may cause false-positive hypermetabolism in the absence of relapse.

Operative Technique and Complication Management in a Case of Giant Esthesioneuroblastoma Resected by a Combined Transcranial and Endonasal Endoscopic Approach: Technical Case Report

BACKGROUND AND IMPORTANCE

Esthesioneuroblastoma (ENB) is a rare anterior skull base tumor derived from olfactory epithelium. There are very few operative videos in the literature demonstrating the surgical resection techniques for giant ENB because of their rarity and complexity. In this technical report, we demonstrate the microsurgical resection of a very large and complex high-grade ENB, initially deemed unresectable, through a bifrontal craniotomy and extended subfrontal approach combined with an endonasal endoscopic approach.

CLINICAL PRESENTATION

A 34-year-old woman presented with headaches, nasal congestion, and bloody nasal drainage. MRI showed a large nasal cavity mass with extension into the anterior cranial fossa and bifrontal lobes. There was significant bifrontal edema causing headaches and abutting the optic nerves. Initial management with surgical resection was offered to the patient for local tumor control and to preserve her vision. A combined bifrontal craniotomy and endonasal transsphenoidal approach was used for resecting this giant tumor. After achieving gross total resection, we reconstructed the anterior skull base in layers. She developed several postoperative complications which were appropriately managed.

CONCLUSION

We demonstrate the surgical resection of a giant ENB through a combined transcranial and endonasal endoscopic approach. We discuss the several postoperative complications in this complex case and the lessons learned.

Ga-68 DOTATATE PET/CT in the Evaluation of Paragangliomas and Other Indeterminate Lesions in the Head and Neck

Background and Purpose

Paragangliomas (PGLs) are rare neuroendocrine tumors with imaging features that can overlap with other entities. This study hypothesizes that given overexpression of somatostatin receptor (SSTR) 2, PGLs can be differentiated on Ga-68 DOTATATE positron emission tomography/computed tomography (PET/CT) from other benign or malignant lesions.

Materials and Methods

Ninety-six patients with known tumors of the head and neck who underwent Ga-68 DOTATATE PET/CT from May 2017 to December 2021 were retrospectively reviewed from a single institution. Of these, 43 patients had histopathological confirmation and 66 positive lesions were discovered on PET/CT. For each lesion, the SUV max, the SUV lesion to liver ratio, and the SUV lesion to spleen ratio were analyzed.

Results

PGLs (n = 37) showed the most intense uptake, and the mean of SUVmax was 69.3 (range 3.7-225.9). Metastatic PGL and metastasis from other neuroendocrine tumors (n = 13) demonstrated intermediate uptake, the mean of SUVmax was 15.16 (range 2.3-40.3). Meningiomas (n = 3) had intermediate uptake, and the mean of SUVmax was 12.37 (range 2.5-19.4). One patient with esthesioneuroblastoma had 5 lesions in the head and neck, and the mean of SUVmax was 18.9 (range 6.9-49.4). Schwannomas (n = 4) had very low uptake, and the mean of SUVmax was 1.75 (range 1.1-2.2). Other rare cases with low uptake included 1 each of osteosarcoma, acinic cell carcinoma, ectopic thyroid tissue, and plasmacytoma, and the mean of SUVmax was 4.75 (range 2.3-6.1).

Conclusions

Ga-68 DOTATATE PET/CT can be a useful adjunct in differentiating tumors in the head and neck. PGLs demonstrate the highest uptake. Meningioma, esthesioneuroblastoma, and neuroendocrine tumor metastasis have intermediate uptake. Schwannomas and other rare tumors exhibit low uptake.

Clinical outcomes, Kadish-INSICA staging and therapeutic targeting of somatostatin receptor 2 in olfactory neuroblastoma

INTRODUCTION

Olfactory neuroblastoma (ONB) is a rare cancer of the sinonasal region. We provide a comprehensive analysis of this malignancy with molecular and clinical trial data on a subset of our cohort to report on the potential efficacy of somatostatin receptor 2 (SSTR2)-targeting imaging and therapy.

METHODS

We conducted a retrospective analysis of 404 primary, locally recurrent, and metastatic olfactory neuroblastoma (ONB) patients from 12 institutions in the United States of America, United Kingdom and Europe. Clinicopathological characteristics and treatment approach were evaluated. SSTR2 expression, SSTR2-targeted imaging and the efficacy of peptide receptor radionuclide therapy [PRRT](177Lu-DOTATATE) were reported in a subset of our cohort (LUTHREE trial; NCT03454763).

RESULTS

Dural infiltration at presentation was a significant predictor of overall survival (OS) and disease-free survival (DFS) in primary cases (n = 278). Kadish-Morita staging and Dulguerov T-stage both had limitations regarding their prognostic value. Multivariable survival analysis demonstrated improved outcomes with lower stage and receipt of adjuvant radiotherapy. Prophylactic neck irradiation significantly reduces the rate of nodal recurrence. 82.4% of the cohort were positive for SSTR2; treatment of three metastatic cases with SSTR2-targeted peptide-radionuclide receptor therapy (PRRT) in the LUTHREE trial was well-tolerated and resulted in stable disease (SD).

CONCLUSIONS

This study presents pertinent clinical data from the largest dataset, to date, on ONB. We identify key prognostic markers and integrate these into an updated staging system, highlight the importance of adjuvant radiotherapy across all disease stages, the utility of prophylactic neck irradiation and the potential efficacy of targeting SSTR2 to manage disease.

Neuroblastoma xenograft models demonstrate the therapeutic potential of 177Lu-octreotate

BACKGROUND

Neuroblastoma (NB) is one of the most frequently diagnosed tumors in infants. NB is a neuroendocrine tumor type with various characteristics and features, and with diverse outcome. The most malignant NBs have a 5-year survival rate of only 40-50%, indicating the need for novel and improved treatment options. 177Lu-octreotate is routinely administered for treatment of neuroendocrine tumors overexpressing somatostatin receptors (SSTR). The aim of this study was to examine the biodistribution of 177Lu-octreotate in mice bearing aggressive human NB cell lines, in order to evaluate the potential usefulness of 177Lu-octreotate for treatment of NB.

METHODS

BALB/c nude mice bearing CLB-BAR, CLB-GE or IMR-32 tumor xenografts (n = 5-7/group) were i.v. injected with 0.15 MBq, 1.5 MBq or 15 MBq 177Lu-octreotate and sacrificed 1 h, 24 h, 48 h and 168 h after administration. The radioactivity concentration was determined for collected tissue samples, tumor-to-normal-tissue activity concentration ratios (T/N) and mean absorbed dose for each tissue were calculated. Immunohistochemical (IHC) staining for SSTR1-5, and Ki67 were carried out for tumor xenografts from the three cell lines.

RESULTS

High 177Lu concentration levels and T/N values were observed in all NB tumors, with the highest for CLB-GE tumor xenografts (72%IA/g 24 h p.i.; 1.5 MBq 177Lu-octreotate). The mean absorbed dose to the tumor was 6.8 Gy, 54 Gy and 29 Gy for CLB-BAR, CLB-GE and IMR-32, respectively, p.i. of 15 MBq 177Lu-octreotate. Receptor saturation was clearly observed in CLB-BAR, resulting in higher concentration levels in the tumor when lower activity levels where administered. IHC staining demonstrated highest expression of SSTR2 in CLB-GE, followed by CLB-BAR and IMR-32.

CONCLUSION

T/N values for all three human NB tumor xenograft types investigated were high relative to previously investigated neuroendocrine tumor types. The results indicate a clear potential of 177Lu-octreotate as a therapeutic alternative for metastatic NB.

Somatostatin receptor 2 is highly sensitive and specific for Epstein-Barr virus-associated nasopharyngeal carcinoma

Viruses are known drivers of head and neck squamous cell carcinomas (HNSCC), particularly Epstein-Barr virus (EBV) and human papillomavirus (HPV). Both EBV-positive nasopharyngeal carcinoma (EBVNPC) and HPV-positive oropharyngeal SCC (OPSCC) can have overlapping histomorphology and molecular signatures, including nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB) pathway mutations. A recent study showed that NFKB activation in EBVNPC drives somatostatin receptor 2 (SSTR2) expression that is detectable by immunohistochemistry and by imaging with 68-Gadolinium-DOTA-peptide radioconjugate. However, whether a similar NFKB-SSTR2 signaling mechanism exists for other virus-positive HNSCC, namely HPV-positive sinonasal carcinomas and OPSCC, remains unclear. Here we examined SSTR2 expression in a cohort of EBV-positive, HPV-positive, and virus-negative HNSCC with immunohistochemistry. SSTR2 immunohistochemistry was performed on our cohort of primary and/or metastatic EBVNPC, HPV-positive sinonasal SCC, OPSCC, HPV-negative sinonasal and oral cavity SCC, and benign tonsil and adenoid tissue. For SSTR2 staining, the extent was categorized as focal, multifocal, or diffuse, and the intensity was categorized as weak, moderate, or strong. Multifocal/diffuse SSTR2 staining of any intensity was considered positive. Among primary, recurrent, and/or undifferentiated NPC, 90% showed multifocal to diffuse strong SSTR2 expression. One HPV-positive sinonasal carcinoma showed patchy SSTR2 staining. None of the remaining HPV-positive sinonasal carcinomas, OPSCC, or oral cavity HNSCC showed significant SSTR2 staining. Overall, SSTR2 is highly sensitive and specific for EBVNPC and could represent a surrogate biomarker. Among HNSCC assessed here, we recommend testing primary NPC for SSTR2 because of its relevance for diagnosis, associated imaging modalities, and its therapeutic implications for patient care.

Doing Great With DOTATATE: Update on GA-68 DOTATATE Positron Emission Tomography/Computed Tomography and Magnetic Resonance Imaging for Evaluation of Sinonasal Tumors

ABSTRACT

Sinonasal tumors are relatively rare and radiographically challenging to evaluate due to their wide variety of pathologies and imaging features. However, sinonasal tumors possessing somatostatin receptor overexpression have the benefit of utilizing a multimodality anatomic and functional imaging for a more comprehensive evaluation. This is particularly evident with esthesioneuroblastoma, with computed tomography and magnetic resonance imaging defining the anatomic extent of the tumor, whereas somatostatin receptor imaging, particularly with gallium-68 DOTATATE positron emission tomography/computed tomography, is used to assess the presence of metastatic disease for staging purposes as well as in the surveillance for tumor recurrence. In addition, areas which accumulate gallium-68 DOTATATE are potentially amenable to treatment with peptide receptor radionuclide therapy. In this manner, a combined approach of anatomic and functional imaging is critical for optimal imaging evaluation and treatment strategy of patients with sinonasal tumors.

The value of 68 Gallium-DOTATATE PET/CT in sinonasal neuroendocrine tumor management: A case series

BACKGROUND

⁶⁸ Gallium-DOTATATE (⁶⁸ Ga-DOTATATE) is a somatostatin analog used as a PET tracer to successfully identify neuroendocrine tumors (NETs). Due to the rarity of sinonasal NETs, there are few recommendations for ⁶⁸ Ga-DOTATATE imaging in these patients.

METHODS

We discussed the impact of ⁶⁸ Ga-DOTATATE imaging on the management of six sinonasal NET cases and reviewed existing literature.

RESULTS

⁶⁸ Ga-DOTATATE PET/CT revealed an unknown primary in one case and identified metastatic disease in a primary sinonasal small cell neuroendocrine carcinoma (SNEC) patient missed on conventional imaging. In two esthesioneuroblastoma (ENB) patients, ⁶⁸ Ga-DOTATATE detected abnormal radiotracer uptake not present on 18F-FDG PET/CT and identified a patient for treatment with ¹⁷⁷ Lu-DOTATATE.

CONCLUSIONS

This is the one of the first few reports, and the largest series to our knowledge, demonstrating the utility of ⁶⁸ Ga-DOTATATE imaging for primary sinonasal SNEC and ENB. Further study is required to determine its role in sinonasal NET management.

[68Ga]-DOTATATE PET/CT and PET/MRI in the diagnosis and management of esthesioneuroblastoma: illustrative cases

BACKGROUND

Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare sinonasal neuroectodermal malignancy with a slow onset of symptoms, favorable 5-year survival, and a propensity for delayed locoregional recurrence. Current treatment options include resection, adjuvant radiotherapy, and/or chemotherapy; however, because of its rarity and location, determining the optimal treatment for ENB has been challenging.

OBSERVATIONS

ENBs strongly express somatostatin receptors (SSTRs), particularly SSTR2, providing a molecular target for imaging and therapy.

LESSONs

The authors present a case series of ENBs imaged with [68Ga]-DOTATATE PET/MRI and PET/CT and discuss the emerging role of [68Ga]-DOTATATE PET for ENB diagnosis, staging, and treatment response monitoring.

Molecular imaging and therapy of somatostatin receptor positive tumors

Somatostatin receptors (SSTR) are upregulated in the cells of origin that define numerous neuroendocrine neoplasms. PET imaging with ⁶⁸Ga-DOTATATE allows specific targeting of SSTR2A, a single species of SSTR receptor, which is commonly overexpressed in a variety of gastroenteropancreatic neuroendocrine tumors, as well as pulmonary carcinoid and head and neck tumors. Due to more specific targeting of SSTR2 as well as lower radiation dose, shorter study length, ability to quantify uptake, and lower cost, ⁶⁸Ga-DOTATATE has demonstrated superior imaging attributes when compared to ¹¹¹In-pentetreotide. As with any novel imaging modality, dedicated training, increasing experience and staying up-to-date with scientific publications are required to provide optimal patient care. The purpose of this review is to summarize the current state of the art in SSTR-targeted molecular imaging and discuss ongoing and future potential diagnostic and therapeutic applications.