Efficacy and Safety of 225 Ac-DOTATATE in the Treatment of Neuroendocrine Neoplasms With High SSTR Expression

PURPOSE

We aimed to evaluate the efficacy and safety of 225 Ac-DOTATATE targeted α therapy (TAT) in various neuroendocrine neoplasms (NENs) with high somatostatin receptor (SSTR) expression.

PATIENTS AND METHODS

This single-center prospective study included 10 patients with histologically diagnosed NENs that exhibited increased SSTR expression on 68 Ga-DOTATATE PET/CT imaging. All patients received 225 Ac-DOTATATE TAT. The primary end points were molecular imaging-based response and disease control rate (DCR), measured using the slightly modified Positron Emission Tomography Response Criteria in Solid Tumors 1.0. The secondary end points were adverse event profiles and clinical responses. The adverse event profile was determined according to the Common Terminology Criteria for Adverse Events version 5.0. Clinical response was assessed using the EORTC QLQ-C30 v3.0 (European Organization for Research and Treatment of Cancer Core Quality of Life questionnaire version 3.0).

RESULTS

A molecular imaging-based partial response was observed in 40% of all patients, SD in 40%, PD in 20%, and DCR in 80%. The DCR was 83.3% (5/6) in patients who were previously treated with 177 Lu-DOTATATE. According to the EORTC QLQ-C30 v3.0 score, most symptoms improved after 225 Ac-DOTATATE treatment, with only diarrhea showing no improvement. Grade III/IV hematological, kidney, and liver toxicities were not observed. The median follow-up time was 14 months (7-22 months), and no deaths were reported.

CONCLUSIONS

This initial study suggests that 225 Ac-DOTATATE is a potentially promising option for treating NENs with elevated SSTR expression, with an acceptable toxicity profile and well-tolerated adverse effects.

177 Lu-DOTATATE Salvage Therapy in Rapidly Progressing Neuroendocrine Tumor With Poor Performance Status

ABSTRACT

Peptide receptor radionuclide therapy (PRRT) has shown to be effective and safe in metastatic gastroenteropancreatic and nongastroenteropancreatic neuroendocrine tumors. However, the selection criteria for PRRT are restricted to patients with good performance status (Eastern Cooperative Oncology Group score ≤2 or Karnofsky performance score ≥60). This denies many patients with adequate somatostatin receptor expression and biochemical profiles from the beneficial effects of PRRT on the quality of life, daily function, and overall survival. The 2 cases highlight the favorable response of PRRT in patients with metastatic neuroendocrine tumor having a very poor performance status initially.

Safety and efficacy of peptide receptor radionuclide therapy in neuroendocrine tumors: A single center experience

Peptide receptor radionucleotide therapy (PRRT) with 177Lu-dotatate is widely used for the treatment of patients with neuroendocrine tumors (NETs). We analyzed data from 104 patients with NETs treated with 177Lu -dotatate at a US academic center between December 2017 and October 2020 to better understand patterns of long-term efficacy, safety, and toxicity in the real-world setting. 177Lu-dotatate (200 mCi) was administered every eight weeks for four doses. The most common sites of primary disease were small intestine NETs (n = 49, 47%), pancreatic NETs (n = 32, 31%), and lung NETs (n = 7, 7%). Twenty-seven percent had Ki-67 <3%, 49% had Ki-67 between 3-20%, and 13.5% had Ki-67 >20%. The cohort had been pretreated with a median of two prior lines of treatment. Forty percent had received prior liver-directed treatment. Seventy-four percent of patients completed all four doses of treatment. The objective response rate was 18%. The median time-to-treatment failure/death was significantly longer for small-bowel NETs when compared to pancreatic NETs (37.3 months vs. 13.2 months, p = 0.001). In a multivariate model, Ki-67, primary site, and liver tumor burden ≥50% were found to independently predict time-to-treatment failure/death. Around 40% of patients experienced adverse events of ≥grade 3 severity. Treatment-related adverse events leading to discontinuation of therapy happened in 10% of patients. Preexisting mesenteric/peritoneal disease was present in 33 patients; seven of these patients developed bowel-related toxicities including two grade 5 events. We also report two cases of delayed-onset minimal change nephrotic syndrome, which occurred 14 and 27 months after the last dose of PRRT. Lastly, we describe six patients who developed rapid tumor progression in the liver leading to terminal liver failure within 7.3 months from the start of PRRT, and identify potential risk factors associated with this occurrence, which will need further study.

Radionuclide Theranostics in Neuroendocrine Neoplasms: An Update

PURPOSE OF REVIEW

This paper aims to address the latest findings in neuroendocrine tumor (NET) theranostics, focusing on new evidence and future directions of combined diagnosis with positron emission tomography (PET) and treatment with peptide receptor radionuclide therapy (PRRT).

RECENT FINDINGS

Following NETTER-1 trial, PRRT with [177Lu]Lu-DOTATATE was approved by FDA and EMA and is routinely employed in advanced G1 and G2 SST (somatostatin receptor)-expressing NET. Different approaches have been proposed so far to improve the PRRT therapeutic index, encompassing re-treatment protocols, combinations with other therapies and novel indications. Molecular imaging holds a potential added value in characterizing disease biology and heterogeneity using different radiopharmaceuticals (e.g., SST and FDG) and may provide predictive and prognostic parameters. Response assessment criteria are still an unmet need and new theranostic pairs showed preliminary encouraging results. PRRT for NET has become a paradigm of modern theranostics. PRRT holds a favorable toxicity profile, and it is associated with a prolonged time to progression, reduction of symptoms, and improved patients' quality of life. In light of further optimization, different new strategies have been investigated, along with the development of new radiopharmaceuticals.

SPECT/CT Image-Derived Absorbed Dose to Red Marrow Correlates with Hematologic Toxicity in Patients Treated with [177Lu]Lu-DOTATATE

Hematologic toxicity, although often transient, is the most common limiting adverse effect during somatostatin peptide receptor radionuclide therapy. This study investigated the association between Monte Carlo-derived absorbed dose to the red marrow (RM) and hematologic toxicity in patients being treated for their neuroendocrine tumors. Methods: Twenty patients each receiving 4 treatment cycles of [177Lu]Lu-DOTATATE were included. Multiple-time-point 177Lu SPECT/CT imaging-based RM dosimetry was performed using an artificial intelligence-driven workflow to segment vertebral spongiosa within the field of view (FOV). This workflow was coupled with an in-house macroscale/microscale Monte Carlo code that incorporates a spongiosa microstructure model. Absorbed dose estimates to RM in lumbar and thoracic vertebrae within the FOV, considered as representations of the whole-body RM absorbed dose, were correlated with hematologic toxicity markers at about 8 wk after each cycle and at 3- and 6-mo follow-up after completion of all cycles. Results: The median of absorbed dose to RM in lumbar and thoracic vertebrae within the FOV (D median,vertebrae) ranged from 0.019 to 0.11 Gy/GBq. The median of cumulative absorbed dose across all 4 cycles was 1.3 Gy (range, 0.6-2.5 Gy). Hematologic toxicity was generally mild, with no grade 2 or higher toxicity for platelets, neutrophils, or hemoglobin. However, there was a decline in blood counts over time, with a fractional value relative to baseline at 6 mo of 74%, 97%, 57%, and 97%, for platelets, neutrophils, lymphocytes, and hemoglobin, respectively. Statistically significant correlations were found between a subset of hematologic toxicity markers and RM absorbed doses, both during treatment and at 3- and 6-mo follow-up. This included a correlation between the platelet count relative to baseline at 6-mo follow up: D median,vertebrae (r = -0.64, P = 0.015), D median,lumbar (r = -0.72, P = 0.0038), D median,thoracic (r = -0.58, P = 0.029), and D average,vertebrae (r = -0.66, P = 0.010), where D median,lumbar and D median,thoracic are median absorbed dose to the RM in the lumbar and thoracic vertebrae, respectively, within the FOV and D average,vertebrae is the mass-weighted average absorbed dose of all vertebrae. Conclusion: This study found a significant correlation between image-derived absorbed dose to the RM and hematologic toxicity, including a relative reduction of platelets at 6-mo follow up. These findings indicate that absorbed dose to the RM can potentially be used to understand and manage hematologic toxicity in peptide receptor radionuclide therapy.

Prevalence of metastases outside the liver and abdominal lymph nodes on 68Ga-DOTATOC-PET/CT in patients with small intestinal and pancreatic neuroendocrine tumours

Metastases outside the liver and abdominal/retroperitoneal lymph nodes are nowadays detected frequently in patients with neuroendocrine tumours (NETs), owing to the high sensitivity of positron emission tomography (PET) with Gallium-68-DOTA-somatostatin analogues (68Ga-SSA) and concomitant diagnostic computed tomography (CT). Our aim was to determine the prevalence of extra-abdominal metastases on 68Ga-DOTATOC-PET/CT in a cohort of patients with small intestinal (Si-NET) and pancreatic NET (Pan-NET), as well as that of pancreatic metastasis in patients with Si-NET. Among 2090 patients examined by 68Ga-DOTATOC-PET/CT at two tertiary referral centres, a total of 1177 patients with a history of Si- or Pan-NET, were identified. The most recent 68Ga-DOTATOC-PET/CT report for each patient was reviewed, and the location and number of metastases of interest were recorded. Lesions outside the liver and abdominal nodes were found in 26% of patients (n = 310/1177), of whom 21.5% (255/1177) were diagnosed with Si-NET and 4.5% (55/1177) Pan-NET. Bone metastases were found in 18.4% (215/1177), metastases to Virchow's lymph node in 7.1% (83/1177), and lung/pleura in 4.8% (56/1177). In the subset of 255 Si-NET patients, 5.4% (41/255) manifested lesions in the pancreas, 1.5% in the breast (18/255), 1.3% in the heart (15/255) and 1% in the orbita (12/255). In Si-NET patients, the Ki-67 proliferation index was higher in those with ≥2 metastatic sites of interest, than with 1 metastatic site, (p <0.001). Overall, extra-abdominal or pancreatic metastases were more often found in patients with Si-NET (34%) than in those with Pan-NET (13%) (p <0.001). Bone metastases were 2.6 times more frequent in patients with Si-NET compared to Pan-NET patients (p <0.001). Lesions to the breast and orbita were encountered in almost only Si-NET patients. In conclusion, lesions outside the liver and abdominal nodes were detected in as many as 26% of the patients, with different prevalence and metastatic patterns in patients with Si-NET compared to Pan-NET. The impact of such metastases on overall survival and clinical decision-making needs further evaluation.

Peptide receptor radionuclide therapy with 177Lu- or 90Y-SSTR peptides in malignant pheochromocytomas (PCCs) and paragangliomas (PGLs): results from a single institutional retrospective analysis

BACKGROUND

Malignant pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare tumors and available systemic therapies are limited.

AIM

To explore the role of peptide receptor radionuclide therapy (PRRT) with Yttrium-90 (90Y) and Lutetium-177 (177Lu) peptides in pheochromocytomas (PCCs) and paragangliomas (PGLs).

METHODS

We retrospectively analyzed more than 1500 patients with histologically proven neuroendocrine tumors treated with 177Lu- or 90Y-DOTA-TATE or -TOC between 1999 to 2017 at our Institute. Overall, 30 patients with confirmed malignant PCCs and PGLs matched inclusion/exclusion criteria and were considered eligible for this analysis.

RESULTS

Thirty (n = 30) patients were treated: 22 with PGLs and 8 with PCCs (12 M and 18 F, median age 47 [IQR: 35-60 years]). Eighteen patients (n = 18) had head and neck PGLs, 3 patients thoracic PGLs and 1 patient abdominal PGL. Sixteen patients (53%) had locally advanced and fourteen (47%) had metastatic disease. Twenty-seven (90%) patients had disease progression at baseline. Four (13%) patients were treated with 90Y, sixteen (53%) with 177Lu and ten (33%) with 90Y + 177Lu respectively. The median total cumulative activity from treatment with 90Y- alone was 9.45 GBq (range 5.11-14.02 GBq), from 177Lu- alone was 21.9 GBq (7.55-32.12 GBq) and from the combination treatment was 4.94 GBq from 90Y- and 6.83 GBq from 177Lu- (ranges 1.04-10.1 and 2.66-20.13 GBq, respectively). Seven out of 30 (23%) patients had partial response and 19 (63%) stable disease. Median follow up was 8.9 years (IQR: 2.9-12). The 5-y and 10-y PFS was 68% (95% CI: 48-82) and 53% (95% CI: 33-69), respectively, whereas 5-y and 10-y OS was 75% (95% CI: 54-87) and 59% (95% CI: 38-75), respectively. Grade 3 or 4 acute hematological toxicity occurred in three patients, two with leucopenia and one with thrombocytopenia, respectively.

CONCLUSION

PRRT with 177Lu- or 90Y-DOTA-TATE or -TOC is feasible and well tolerated in advanced PGLs and PCCs.

Effectiveness and Safety of Retreatment with 177Lu-DOTATATE in Patients with Progressive Neuroendocrine Tumors: A Retrospective Real-World Study in the United States

Advanced neuroendocrine tumors (NETs) are associated with a poor prognosis. A regimen of 4 cycles of 177Lu-DOTATATE has been shown to improve both progression-free survival (PFS) and overall survival (OS) in patients with advanced NETs. To the best of our knowledge, this is the first study in the United States to evaluate the effectiveness and safety of additional cycles of 177Lu-DOTATATE therapy in patients with progressive NETs. Methods: This was a retrospective chart review of adults with advanced NETs. The patients had undergone initial treatment with up to 4 cycles of 177Lu-DOTATATE and, after disease progression and a period of at least 6 mo since the end of the initial treatment, were retreated with at least 1 additional cycle at a single center (2010-2020). Patient characteristics, treatment patterns, and clinical outcomes were evaluated descriptively. Response was evaluated according to RECIST 1.1; toxicity was defined using criteria from Common Terminology Criteria for Adverse Events, version 5.0. Kaplan-Meier plots were used to evaluate PFS and OS. Results: Of the 31 patients who received 177Lu-DOTATATE retreatment, 61% were male and 94% were White. Overall, patients received a median of 6 cycles (4 initial cycles and 2 retreatment cycles), and the mean administered activity was 41.9 GBq. Two patients also went on to receive additional retreatment (1 and 2 cycles, individually) after a second period of at least 6 mo and progression after retreatment. Best responses of partial response and stable disease were observed in 35% and 65% of patients after the initial treatment and 23% and 45% of patients after retreatment, respectively. The median PFS after the initial treatment was 20.2 mo and after retreatment was 9.6 mo. The median OS after the initial treatment was 42.6 mo and after retreatment was 12.6 mo. Hematologic parameters decreased significantly during both the initial treatment and retreatment but recovered such that there was little difference between the values before the initial treatment and before the retreatment. Clinically significant hematotoxicity occurred in 1 and 3 patients after the initial treatment and retreatment, respectively. No grade 3 or 4 nephrotoxicity was observed. Conclusion: Retreatment with 177Lu-DOTATATE after progression appeared to be well tolerated and offered disease control in patients with progressive NETs after initial 177Lu-DOTATATE treatment.

Deep transformer-based personalized dosimetry from SPECT/CT images: a hybrid approach for [177Lu]Lu-DOTATATE radiopharmaceutical therapy

PURPOSE

Accurate dosimetry is critical for ensuring the safety and efficacy of radiopharmaceutical therapies. In current clinical dosimetry practice, MIRD formalisms are widely employed. However, with the rapid advancement of deep learning (DL) algorithms, there has been an increasing interest in leveraging the calculation speed and automation capabilities for different tasks. We aimed to develop a hybrid transformer-based deep learning (DL) model that incorporates a multiple voxel S-value (MSV) approach for voxel-level dosimetry in [177Lu]Lu-DOTATATE therapy. The goal was to enhance the performance of the model to achieve accuracy levels closely aligned with Monte Carlo (MC) simulations, considered as the standard of reference. We extended our analysis to include MIRD formalisms (SSV and MSV), thereby conducting a comprehensive dosimetry study.

METHODS

We used a dataset consisting of 22 patients undergoing up to 4 cycles of [177Lu]Lu-DOTATATE therapy. MC simulations were used to generate reference absorbed dose maps. In addition, MIRD formalism approaches, namely, single S-value (SSV) and MSV techniques, were performed. A UNEt TRansformer (UNETR) DL architecture was trained using five-fold cross-validation to generate MC-based dose maps. Co-registered CT images were fed into the network as input, whereas the difference between MC and MSV (MC-MSV) was set as output. DL results are then integrated to MSV to revive the MC dose maps. Finally, the dose maps generated by MSV, SSV, and DL were quantitatively compared to the MC reference at both voxel level and organ level (organs at risk and lesions).

RESULTS

The DL approach showed slightly better performance (voxel relative absolute error (RAE) = 5.28 ± 1.32) compared to MSV (voxel RAE = 5.54 ± 1.4) and outperformed SSV (voxel RAE = 7.8 ± 3.02). Gamma analysis pass rates were 99.0 ± 1.2%, 98.8 ± 1.3%, and 98.7 ± 1.52% for DL, MSV, and SSV approaches, respectively. The computational time for MC was the highest (~2 days for a single-bed SPECT study) compared to MSV, SSV, and DL, whereas the DL-based approach outperformed the other approaches in terms of time efficiency (3 s for a single-bed SPECT). Organ-wise analysis showed absolute percent errors of 1.44 ± 3.05%, 1.18 ± 2.65%, and 1.15 ± 2.5% for SSV, MSV, and DL approaches, respectively, in lesion-absorbed doses.

CONCLUSION

A hybrid transformer-based deep learning model was developed for fast and accurate dose map generation, outperforming the MIRD approaches, specifically in heterogenous regions. The model achieved accuracy close to MC gold standard and has potential for clinical implementation for use on large-scale datasets.

177Lu-Dotatate administration using an infusion pump or a peristaltic pump: comparison of two methods

OBJECTIVES

177Lu-oxodotreotide (Lutathera) is an intravenous peptide receptor radionuclide therapy to treat unresectable metastatic digestive neuroendocrine tumours. The recommended method for Lutathera administration is gravity infusion; however, other appropriate and safe techniques are possible. This work compares two infusion methods from a medico-economic, radiation protection, efficiency and practicality point of view.

METHODS

Two infusion methods were studied, either involving a volumetric infusion pump (method 1) or a peristaltic pump (method 2). For each method, the mean residual activity per vial and the mean injection time were compared. Occupational radiation exposure was measured. The cost of initial equipment and consumables for one administration was determined. Feedback from operators and past incidents during injections were collected through a survey.

RESULTS

Three operators performed 219 Lutathera injections over 70 months: 60.7% (133) with method 1 and 39.3% (86) with method 2. After infusion, the mean residual activity in vial was 124.3±16.9 MBq with method 1 and 80.9±19.3 MBq with method 2 (34.9% decrease). The average administration time was 41±7.2 min with method 1 and 39±8.5 min with method 2. Occupational exposures obtained with both methods were very low and quite similar. Method 1 required an initial investment of 1165.8 US$ plus 4.0 US$ of supplies for each administration. Initial investment for method 2 was comparable (1261.4 US$) but supplies cost per administration was higher (12.5 US$). Two major incidents were recorded with method 1 and none with method 2. From operators' experience, method 2 felt safer and more suitable.

CONCLUSIONS

Method 2 appeared to be convenient and secure, despite a higher cost per injection. It could also be applied to new radioligand therapies such as 177Lu-PSMA or 225Ac-Dotatate.

PRRT with Lu-177 DOTATATE in Treatment-Refractory Progressive Meningioma: Initial Experience from a Tertiary-Care Neuro-Oncology Center

PURPOSE

Refractory and/or recurrent meningiomas have poor outcomes, and the treatment options are limited. Peptide receptor radionuclide therapy (PRRT) has been used in this setting with promising results. We have documented our experience of using intravenous (IV) and intra-arterial (IA) approaches of Lu-177 DOTATATE PRRT.

METHODS

Eight patients with relapsed/refractory high-grade meningioma received PRRT with Lu-177 DOTATATE by IV and an IA route. At least 2 cycles were administered. Time to progression was calculated from the first PRRT session to progression. The response was assessed on MRI using RANO criteria, and visual analysis of uptake was done on Ga-68 DOTANOC PET/CT. Post-therapy dosimetry calculations for estimating the absorbed dose were performed.

RESULTS

Median time to progression was 8.9 months. One patient showed disease progression, whereas seven patients showed stable disease at 4 weeks following 2 cycles of PRRT. Dosimetric analysis showed higher dose and retention time by IA approach. No significant peri-procedural or PRRT associated toxicity was seen.

CONCLUSION

PRRT is a safe and effective therapeutic option for relapsed/refractory meningioma. The IA approach yields better dose delivery and should be routinely practised.

Al18F-NOTA-Octreotide PET/CT and 18F-FDG PET/CT for Detecting Cerebellar Hemangioblastoma in a Patient With Von Hippel-Lindau Disease

ABSTRACT

Von Hippel-Lindau disease is a hereditary syndrome associated with various benign and malignant tumors, including hemangioblastomas. A 42-year-old man with a history of Von Hippel-Lindau disease underwent surgery for pancreatic neuroendocrine tumor and renal clear cell carcinoma and was recommended to undergo Al18F-NOTA-octreotide and 18F-FDG PETCT examination to assess potential metastases. 18F-FDG PET/CT showed low uptake in the right cerebellum, which demonstrated increased Al18F-NOTA-octreotide activity. Cerebellar mass resection surgery was performed. Pathological result was consistent with hemangioblastoma. This case report indicates the significant role of Al18F-NOTA-octreotide in the diagnosis of hemangioblastoma.

Evaluation of the SSTR2-targeted Radiopharmaceutical 177Lu-DOTATATE and SSTR2-specific 68Ga-DOTATATE PET as Imaging Biomarker in Patients with Intracranial Meningioma

PURPOSE

There are no effective medical therapies for patients with meningioma who progress beyond surgical and radiotherapeutic interventions. Somatostatin receptor type 2 (SSTR2) represents a promising treatment target in meningiomas. In this multicenter, single-arm phase II clinical study (NCT03971461), the SSTR2-targeting radiopharmaceutical 177Lu-DOTATATE is evaluated for its feasibility, safety, and therapeutic efficacy in these patients.

PATIENTS AND METHODS

Adult patients with progressive intracranial meningiomas received 177Lu-DOTATATE at a dose of 7.4 GBq (200 mCi) every eight weeks for four cycles. 68Ga-DOTATATE PET-MRI was performed before and six months after the start of the treatment. The primary endpoint was progression-free survival (PFS) at 6 months (PFS-6). Secondary endpoints were safety and tolerability, overall survival (OS) at 12 months (OS-12), median PFS, and median OS.

RESULTS

Fourteen patients (female = 11, male = 3) with progressive meningiomas (WHO 1 = 3, 2 = 10, 3 = 1) were enrolled. Median age was 63.1 (range 49.7-78) years. All patients previously underwent tumor resection and at least one course of radiation. Treatment with 177Lu-DOTATATE was well tolerated. Seven patients (50%) achieved PFS-6. Best radiographic response by modified Macdonald criteria was stable disease (SD) in all seven patients. A >25% reduction in 68Ga-DOTATATE uptake (PET) was observed in five meningiomas and two patients. In one lesion, this corresponded to >50% reduction in bidirectional tumor measurements (MRI).

CONCLUSIONS

Treatment with 177Lu-DOTATATE was well tolerated. The predefined PFS-6 threshold was met in this interim analysis, thereby allowing this multicenter clinical trial to continue enrollment. 68Ga-DOTATATE PET may be a useful imaging biomarker to assess therapeutic outcome in patients with meningioma.

Peptide Receptor Radionuclide Therapy Using 177Lu-DOTATATE: Nursing Roles in Managing Patients With Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a diverse family of cancers that occur within the gastrointestinal tract and pancreas. Peptide receptor radionuclide therapy (PRRT) via 177Lu-DOTATATE is a newer therapeutic option for certain patients with somatostatin receptor-positive GEP-NETs.

OBJECTIVES

This review informs on how oncology nurses treating patients with GEP-NETs receiving PRRT using 177Lu-DOTATATE can facilitate care.

METHODS

Guidance on the monitoring, management, and care of patients undergoing PRRT for GEP-NETs was developed based on published literature and the nursing experience of the authors. A case study is summarized to highlight key concepts.

FINDINGS

Oncology nurses provide assessment, education, direct care, and emotional support when caring for patients with GEP-NETs receiving PRRT with 177Lu-DOTATATE. As the treatment landscape evolves, so too will these roles and responsibilities.

Al18F-NOTA-Octreotide outperforms 18F-FDG in identifying rare renal metastases from pancreatic neuroendocrine tumor

We presented a case involving a 56-year-old man who had been experiencing shoulder and back pain for over a year, with extensive bone metastases revealed by a bone scan. To identify the primary source of these issues, the patients underwent a fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scan, which indicated moderate uptake in the right renal soft mass and low uptake in multiple osteolytic lesions. Pathological examination and immunohistochemical staining of the renal mass supported the diagnosis of neuroendocrine tumors. Subsequently, a novel somatostatin receptor imaging agent, Al18F-NOTA-octreotide (18F-OC), was performed to further investigate the source of metastatic lesions and to stage the tumor. The 18F-OC scan revealed a high-uptake lesion in the pancreatic head, as well as additional lymph node and bone metastases lesions. Compared to 18F-FDG, the 18F-OC demonstrated superior imaging capabilities and a significantly higher tumor-to-background ratio in neuroendocrine neoplasms, which contributed to improving the staging and treatment management.

[68Ga-DOTATOC PET/CT for Diagnosing Neuroendocrine Tumors]

Lutathera is a peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumors and was approved as the first PRRT drug in Japan in 2021. Although neuroendocrine tumors are often less aggressive than other highly malignant and invasive tumors, there have been few effective therapy options, so "Lutathera"is a long-awaited treatment. Lutathera is indicated for the treatment of "somatostatin receptor-positive neuroendocrine tumors". Currently, in Japan, the only imaging method to evaluate the expression of somatostatin receptors in lesions is scintigraphy using In-111 pentetreotide(OctreoScan). In this section, we would like to introduce the current status of the 68Ga-DOTA-SSA PET/CT using somatostatin analogue(SSA)in our institution.

Rechallenge With Additional Doses of 177 Lu-DOTATOC After Failure of Maintenance Therapy With Cold Somatostatin Analogs

ABSTRACT

Here, we report a case of a 52-year-old woman with a well-differentiated, metastasized neuroendocrine tumor (NET G1) of the duodenum. Initial imaging with 68 Ga-DOTATOC revealed multiple sites of disease with intense uptake. Peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTATOC induced partial remission. Treatment was then switched to cold somatostatin analog as a maintenance therapy. After 2 years of follow-up, progressive disease with multiple lesions in the skeleton was noted. Given the initial response to PRRT, a rechallenge with another 2 cycles of PRRT were given, and the patient had an excellent response to treatment, in particular in the skeleton.

Role of 68Ga-DOTATOC PET/CT in Insulinoma According to 3 Different Contexts: A Retrospective Study

OBJECTIVE

The aim of this study was to assess the performance of 68Ga-DOTATOC PET/CT in the detection and extension of insulinomas according to 3 different contexts: sporadic benign, sporadic metastatic, and multiple endocrine neoplasia type 1 (MEN1).

PATIENTS AND METHODS

The data of 71 adult patients who underwent 68Ga-DOTATOC PET/CT for suspected or confirmed sporadic insulinoma, suspicion of insulinoma in the context of MEN1, follow-up of metastatic insulinoma, or suspicion of recurrence of insulinoma were retrospectively analyzed. Pathological examination or strong clinical and biological findings were used as standards of truth.

RESULTS

For the assessment of a confirmed sporadic insulinoma in 17 patients, the sensitivity of SR-PET was 75%, including 2 patients for whom metastatic lesions had been revealed by SR-PET. For 35 patients with a suspicion of insulinoma, the sensitivity was 39%. In 10 patients followed up for metastatic insulinoma, the sensitivity was 100%. For 5 patients with a history of MEN1, interpretation of SR-PET was difficult, as 3 of them presented with multiple pancreatic uptake foci. The global sensitivity of SR-PET in all insulinomas excluding those with a MEN1 story was 64% (100% for metastatic insulinomas, 62% for benign insulinomas), with a specificity of 89%.

CONCLUSIONS

68Ga-DOTATOC PET/CT is a useful examination tool for the assessment of insulinomas in selected contexts, with very high performance for the detection and extension workup of metastatic insulinomas and high specificity for the detection of sporadic benign insulinomas. The examination should be completed with GLP-1 receptor PET when it is negative or in a MEN1 context.

Peptide receptor radionuclide therapy implementation and results in a predominantly gastrointestinal neuroendocrine tumor population: A two-year experience in a nonuniversity setting

Neuroendocrine tumors (NETs) are rare, but the incidence and prevalence of NETs are increasing in the United States. While surgery is the preferred treatment for NETs, it is not a viable option for metastatic disease. Lutathera (177Lu-DOTATATE) is approved by the United States Food and Drug Administration and the European Medicines Agency for the treatment of gastroenteropancreatic (GEP)-NETs in adults. There is limited information on GEP-NET treatment responses to Lutathera.Our institution launched a peptide receptor radionuclide therapy (PRRT) service line using Lutathera with involvement from a multidisciplinary team and complete collaboration between hospital administration and clinical providers. A prospective registry study was also established in order to collect patient demographics and clinical data regarding the treatment of GEP primary NETs with Lutathera.Between August 2018 and July 2020, 35 GEP-NET patients were treated with Lutathera, of which 65.71% received 4 complete cycles and 25.71% received 3 cycles; 5.71% and 2.86% received 2 and 1 cycles of PRRT, respectively. Most adverse events during the course of our study were low grade using the common terminology criteria for adverse events system. Of the patients who completed all 4 cycles: 22% showed partial response to Lutathera, 44% showed stable disease, and 13% showed disease progression based on a qualitative assessment of positron emission tomography/computed tomography imaging.From our experience, Lutathera was well tolerated in patients with GEP-NET. Additional studies are needed to examine long-term clinical and patient-reported outcomes associated with GEP-NET treatment as well as financial considerations for hospitals embarking on a PRRT program.

Multiparametric 18F-FDG and 68GA-DOTATOC PET Imaging in Bone Metastatic Meningioma Before Radionuclide Therapy: Assessment of Tumor Heterogeneity

ABSTRACT

This report presents the case of a 61-year-old woman with assessment of fronto-temporo-sphenoidal refractory meningioma before radionuclide therapy with pretherapeutic 68Ga-DOTATOC PET/CT. Given the discovery of osteolytic lesions, 18F-FDG PET/CT is planned to search for the primitive origin. Meningioma bone metastasis is confirmed with spine biopsies. The presence of dedifferentiated meningioma lesions indicating that high somatostatin receptor expression does not necessarily coincide with areas of increased glucose metabolism. 18F-FDG and 68Ga-DOTATOC PET/CT allows optimal characterization of tumor heterogeneity and guide targeted therapeutic management before PPRT.

Recurrence of a Pheochromocytoma With TNEM127 Mutation Negative on 18F-FDOPA and 18F-FDG but Positive on 123I-MIBG and 68Ga-DOTATOC Imaging

ABSTRACT

We report the case of a 75-year-old woman with liver metastasis as a recurrence of a pheochromocytoma resected 10 years ago, with a rare germline mutation in transmembrane protein 127, falsely negative on 18F-FDOPA and 18F-FDG PET/CT scans but strongly positive on 123I-MIBG scintigraphy and on 68Ga-DOTATOC PET/CT. Functional imaging has a key role in diagnosis of pheochromocytoma and paraganglioma, especially 18F-FDOPA shows very high sensitivity and specificity. However, 18F-FDOPA might be falsely negative in some of these tumors, depending on specific mutations, and thus MIBG or 68Ga-DOTATOC imaging could be an alternative.

Breast Carcinoma Shown on 99mTc-HYNIC-TOC Study Performed to Evaluate Tumor-Induced Osteomalacia

ABSTRACT

A 74-year-old woman with a history of suspected tumor-induced osteomalacia underwent 99mTc-HYNIC-TOC scintigraphy to search potential culprit tumor. The images showed one in the middle shaft of left femur without corresponding morphology change on the CT portion of the subsequent SPECT/CT images. The patient declined surgical exploration of the left femur. Another activity was in the right breast, which was resected and pathologically confirmed as breast carcinoma. Postsurgically, the patient's symptoms were not improved. Four years later, a repeat 99mTc-HYNIC-TOC scintigraphy showed more prominent activity in the left femur with gross abnormality on the corresponding CT images.

Intracavernous Schwannoma Characterized With 18F-FDG, 68Ga-DOTATOC, and 18F-Choline PET

ABSTRACT

We report the case of a 75-year-old man with history of prostate cancer whose left intracavernous lesion was successfully characterized by 3 PETs performed successively with different tracers. This poorly characterized tumor was initially discovered on an MRI conducted to investigate an acute diplopia and slowly growing during follow-up. On 18F-FDG PET, the lesion showed no significant uptake, and no extracranial lesion was found nor did it have increased 68Ga-DOTATOC uptake. Finally, this tumor displayed a high 18F-choline uptake, and no extracranial lesion was revealed with this tracer. The diagnosis of schwannoma without malignancy criterion was proven by biopsy.

Detection of Unilateral Axillary Nodal Uptake Both at 68Ga-DOTATOC and 18F-FDG PET/CT After 1 Week From COVID-19 Vaccine

ABSTRACT

Recently, vaccination against COVID-19 has gained wide diffusion, especially among vulnerable individuals, such as cancer patients. At the same time, patients have been undergoing PET/CT examinations after vaccination in an increasing number, and cases of false-positive axillary nodal uptake have been described, mostly at 18F-FDG PET. Here, we describe the case of both 68Ga-DOTATOC and 18F-FDG axillary nodal uptake in a young woman affected by a metastatic retroperitoneal paraganglioma.

Comparing Somatostatin Analogs in the Treatment of Advanced Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

The 2 approved somatostatin analogs (SSAs) in the first-line treatment of advanced, well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are octreotide long-acting release (Sandostatin LAR) and somatuline depot (Lanreotide). The study's objective was to compare progression-free survival (PFS) and overall survival (OS) of patients (pts) with GEP-NETs treated with somatuline or octreotide LAR. Pts and Methods: Pts with advanced well-differentiated GEP-NET who received either SSA at Emory University between 1995 and 2019 were included after institutional review board approval. The primary end point was PFS, defined as time to disease progression (according to the Response Evaluation Criteria in Solid Tumors, version 1.1, or clinical progression) or death. The secondary end point was OS. Kaplan-Meier curves were generated, and log-rank tests were conducted to compare the survival outcomes.

RESULTS

A total of 105 pts were identified. The mean age was 62.1 years (SD ± 11.8). The male-to-female ratio was 51:54. The majority (N = 69, 65.7%) were white. Most pts had grade 2 (G2) disease (N = 44, 41.9%). Primary location was small bowel in 58 (55.2%), pancreas in 27 (25.7%), and other in 20 (19.0%). Functional tumors were defined in 32 pts distributed equally between the 2 groups. Distribution of treatment was similar in the 2 groups, with 54 receiving octreotide LAR and 51 receiving somatuline depot. The median PFS for the octreotide LAR and somatuline depot groups was 12 months (95% CI, 6-18 months) and 10.8 months (95% CI, 6-15.6 months), respectively, and the difference was not statistically significant (p = 0.2665). For pts with G1 disease, the median PFS for the octreotide LAR and somatuline depot was 8.4 versus 32.4 months, respectively, and the difference was not statistically significant (p = 0.159). For G2 disease, the difference in median PFS between octreotide LAR and somutaline depot groups was statistically significant (12 vs. 7.2 months, respectively; p = 0.0372). The mean follow-up time for octreotide LAR was 21.6 months versus 11.3 months for somatuline depot.

CONCLUSIONS

Overall, there was no difference in PFS between octreotide LAR and somatuline depot for pts with well-differentiated, metastatic GEP-NETs. A prospective study is worth designing selecting for G.

External Validation of a Clinical Score for Patients With Neuroendocrine Tumors Under Consideration for Peptide Receptor Radionuclide Therapy

IMPORTANCE

Despite the benefit of peptide receptor radionuclide therapy (PRRT) for patients with well-differentiated neuroendocrine tumors (WD NETs), no clinical metric to anticipate benefit from the therapy for individual patients has been previously defined.

OBJECTIVE

To assess whether the prognostic ability of the clinical score (CS) could be validated in an external cohort of patients with WD NETs.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study's analysis included patients with WD NETs who were under consideration for peptide receptor radionuclide therapy (PRRT) with lutetium-177 (177Lu)-dotatate between March 1, 2016, and March 17, 2020. The original cohort included patients from Vanderbilt-Ingram Cancer Center. The validation cohort included patients from Ochsner Medical Center, Markey Cancer Center, and Rush Medical Center. Patients with paragangliomas, pheochromocytomas and neuroblastomas were excluded. Statistical analysis was performed from June to November 2021.

EXPOSURES

PRRT with 177Lu-dotatate or alternate therapies such as everolimus, sunitinib, or capecitabine plus temozolomide.

MAIN OUTCOMES AND MEASURES

The primary outcome was progression-free survival (PFS) and was estimated by the Kaplan-Meier method; a Cox proportional-hazards model adjusting for primary tumor site, tumor grade, and number of PRRT doses administered was used to analyze association between CS and outcomes.

RESULTS

A total of 126 patients (median age [IQR] age: 63.6 [52.9-70.7] years; 64 male individuals) were included in the validation cohort, and the combined cohort (validation and original cohorts combined) had a total of 248 patients (median [IQR] patient age: 63.3 [53.3-70.3] years; 126 male individuals). In the validation cohort, on multivariable analysis, for each 2-point increase in CS, PFS decreased significantly (hazard ratio, 2.61; 95% CI, 1.64-4.16). After finding an association of the CS with PFS in the validation cohort, the original and validation cohorts were combined into the cohort for this analysis. On multivariable analysis, for each 2-point increase in CS, PFS decreased significantly (hazard ratio, 2.52; 95% CI, 1.89-3.36).

CONCLUSIONS AND RELEVANCE

Increases in CS were associated with worsening PFS in the validation cohort, validating findings from the original cohort. These findings suggest that the CS, to our knowledge, represents the first clinical metric to estimate anticipated benefit from PRRT for patients with WD NETs and may be a clinical tool for patients being considered for PRRT.

Dual-Tracer (68Ga-DOTATOC and 18F-FDG-)-PET/CT Scan and G1-G2 Nonfunctioning Pancreatic Neuroendocrine Tumors: A Single-Center Retrospective Evaluation of 124 Nonmetastatic Resected Cases

INTRODUCTION

The combined use of 68gallium (68Ga)-DOTA-peptides and 18fluorine-fluoro-2-deoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scans in the workup of pancreatic neuroendocrine tumors (PanNETs) is controversial. This study aimed at assessing both tracers' capability to identify tumors and to assess its association with pathological predictors of recurrence.

METHODS

Prospectively collected, preoperative, dual-tracer PET/CT scan data of G1-G2, nonmetastatic, PanNETs that underwent surgery between January 2013 and October 2019 were retrospectively analyzed.

RESULTS

The final cohort consisted of 124 cases. There was an approximately equal distribution of males and females (50.8%/49.2%) and G1 and G2 tumors (49.2%/50.8%). The disease was detected in 122 (98.4%) and 64 (51.6%) cases by 68Ga-DOTATOC and by 18F-FDG PET/CT scans, respectively, with a combined sensitivity of 99.2%. 18F-FDG-positive examinations found G2 tumors more often than G1 (59.4 vs. 40.6%; p = 0.036), and 18F-FDG-positive PanNETs were larger than negative ones (median tumor size 32 mm, interquartile range [IQR] 21 vs. 26 mm, IQR 20; p = 0.019). The median Ki67 for 18F-FDG-positive and -negative examinations was 3 (IQR 4) and 2 (IQR 4), respectively (p = 0.029). At least 1 pathological predictor of recurrence was present in 74.6% of 18F-FDG-positive cases (vs. 56.7%; p = 0.039), whereas this was not found when dichotomizing the PanNETs by their dimensions (≤/>20 mm). None of the 2 tracers predicted nodal metastasis. The receiver operating characteristic curve analysis showed that 18F-FDG uptake higher than 4.2 had a sensitivity of 49.2% and specificity of 73.3% for differentiating G1 from G2 (AUC = 0.624, p = 0.009).

CONCLUSION

The complementary adoption of 68Ga-DOTATOC and 18F-FDG tracers may be valuable in the diagnostic workup of PanNETs despite not being a game-changer for the management of PanNETs ≤20 mm.

225Ac-DOTATOC-Targeted Somatostatin Receptor α-Therapy in a Patient With Metastatic Neuroendocrine Tumor of the Thymus, Refractory to β-Radiation

ABSTRACT

Somatostatin receptor-targeted α-therapy using α-emitter 225Ac-labeled somatostatin analogs has been suggested as a treatment option in advanced metastatic neuroendocrine tumors (NETs) failing treatment with β-emitters, such as 177Lu or 90Y. Thymus NETs are rare and usually more aggressive than other neuroendocrine tumor entities. We present here a case with β-radiation refractory metastatic thymus NET, who demonstrated an excellent therapy response (molecular and morphological remission, as well as significantly improved clinical symptoms) after 225Ac-DOTATOC-targeted α-therapy, without any adverse effects during the treatment or in the follow-up period.

Incidental 68Ga-DOTATOC PET/CT Uptake in Hemorrhagic Transformation of Stroke in a Patient With Cervical Paraganglioma

ABSTRACT

We present a case of a 75-year-old woman with clinical suspicion of stroke whose cranial CT showed ischemic changes in right precentral region, without visible vascular occlusion, and a right vagal lesion suggestive of paraganglioma. Two weeks later, 68Ga-DOTATOC PET/CT with IV iodine-based contrast administration (Biograph 6 True Point equipment; Siemens) was performed for characterization of this lesion and staging. Intraparenchymal 68Ga-DOTATOC uptake was visualized in right frontal lobe suggestive of hemorrhagic transformation of the previous stroke.

Haematotoxicity during peptide receptor radionuclide therapy: Baseline parameters differences and effect on patient's therapy course

BACKGROUND

Mainly severe (CTCAE grade 3-4) haematotoxicity during peptide receptor radionuclide therapy (PRRT) is reported in literature due to major clinical impact, however moderate (CTCAE grade 2) haematotoxicity is common and could affect therapy management. The aim of this study was to evaluate the haematotoxicity course during PRRT and to compare baseline parameters between haematotoxicity grades.

METHODS

In this retrospective study, 100 patients with a neuroendocrine tumour treated with PRRT were included. Patients were treated with an aimed number of four cycles with 7.4 GBq [177Lu]Lu-DOTA-TATE administered every 10 weeks. Haematological assessment was performed at baseline and frequently up to 10 weeks after the fourth cycle. The lowest haematological value was graded according to CTCAE v5.0, and patients were classified using the highest observed grade. Differences in baseline parameters, including [68Ga]Ga-DOTA-TATE positive tumour volume, were evaluated between CTCAE grades.

RESULTS

Four cycles were completed by 86/100 of patients, 4/100 patients discontinued due to haematotoxicity, and 10/100 patients due to progressive disease. The treatment course was adjusted due to haematotoxicity in 24/100 patients, including postponed next cycle (n = 17), reduced administered activity (n = 13), and both adjustments (n = 10). The most observed haematotoxicity grade was grade 0-1 in 54/100 patients, grade 2 in 38/100 and grade 3-4 in 8/100. Significant differences in baseline leucocyte, neutrophil and platelet counts were observed between grade 0-1 and grade 2. However, the correlation between baseline and lowest observed values was poor to moderate. No differences between haematotoxicity grades and baseline parameters or somatostatin receptor positive tumour volume was observed.

CONCLUSIONS

The incidence of severe haematotoxicity was low with extensive screening and monitoring. The vast majority of patients (96/100) was not restricted in treatment continuation by haematotoxicity; therefore, our selection criteria appeared appropriate for safe PRRT treatment. Baseline parameters showed limited correlation with the degree of decline in haematological values.

Breast Cancer Metastasis Mimicking Meningioma in 68Ga-DOTATOC PET/CT

ABSTRACT

68Ga-DOTATOC PET/CT is a reliable imaging modality in the diagnosis and therapy planning of symptomatic meningiomas. We present a case of a 74-year-old woman where a supposed SSTR-positive sphenoid wing meningioma turned out to be a breast cancer metastasis. Our case shows that dural metastases from breast cancer might represent a clinical pitfall in 68Ga-DOTATOC PET/CT.

EVALUATION OF THE SPATIAL RESOLUTION IN MONTE CARLO-BASED SPECT/CT RECONSTRUCTION OF 111IN-OCTREOTIDE IMAGES

The purpose was to evaluate the spatial resolution in 111In-octreotide single-photom emission computed tomography (SPECT)/computed tomography (CT) imaging following reconstructions with three different ordered subset expectation maximizations (OSEM) reconstruction algorithms; attenuation corrected (AC) OSEM, AC OSEM with resolution recovery (ACRR OSEM) and Monte Carlo-based OSEM reconstruction (MC OSEM). SPECT/CT imaging of a triple line phantom containing 111In in air and water was performed. The spatial resolution, represented by the full width at half maximum (FWHM) of a line profile, was determined for each line, for X and Y direction and for all reconstructions. The mean FWHM was 12.2 mm (±standard deviation [SD] 3.7 mm) for AC OSEM, 9.3 mm (±SD 2.5 mm) for ACRR OSEM and 8.2 mm (±SD 2.0 mm) for MC OSEM. MC-based SPECT/CT reconstruction clearly improves the spatial resolution in 111In-octreotide imaging and since MC simulations can be performed for all photon energies MC OSEM has the potential to improve SPECT/CT imaging overall.

Hemorrhagic disseminated intravascular coagulation after 177Lu-Dotatate in metastatic midgut neuroendocrine tumor: A case report

RATIONALE

Peptide receptor radionuclide therapy with 177Lu-Dotatate represents a major breakthrough in the treatment of metastatic well differentiated neuroendocrine tumors. This treatment is generally well tolerated. Reported severe long-term hematological side effects are rare and include hematopoietic neoplasms and bone marrow failure.

PATIENTS CONCERNS

We describe the case of a patient presenting spontaneous bleeding and bruising occurring 6 weeks after the first administration of 177Lu-Dotatate. Blood tests showed anemia, thrombocytopenia, prolonged clotting times, profound fibrinolysis and low levels of coagulation factors II and V. There were no signs of tumor lysis syndrome.

DIAGNOSES

We made the diagnosis of acute disseminated intravascular coagulation.

INTERVENTION

Treatment consisted of multiple transfusions of fresh frozen plasma, fibrinogen and platelets, and corticosteroids. Acute disseminated intravascular coagulation (DIC) persisted for 10 days and then resolved.

OUTCOMES

Metabolic imaging 5 months after the 177Lu-Dotatate administration showed disease progression. Treatment with 177Lu-Dotatate was not rechallenged due to the occurrence of DIC.

LESSONS

Our case suggests that acute hemorrhagic disseminated intravascular coagulation can be a rare and life-threatening subacute side effect of 177Lu-Dotatate peptide receptor radionuclide therapy.

Utility of 18F-AlF-NOTA-Octreotide PET/CT in the Localization of Tumor-Induced Osteomalacia

CONTEXT

Tumor-induced osteomalacia (TIO) is a paraneoplastic disorder, usually caused by benign mesenchymal tumors that produce high levels of fibroblast growth factor 23. The only curative therapy is resection of the causative tumors.

OBJECTIVE

This research was conducted to evaluate the efficacy of 18F-AlF-NOTA-octreotide (18F-OC) positron emission tomography/computed tomography (PET/CT) in detecting TIO and its impact on patient management.

METHODS

Retrospective analysis was conducted of 17 patients with hypophosphatemic osteomalacia suspected to be TIO. A  18F-OC PET/CT study was performed in all 17 patients to localize the tumor and 68Ga-DOTATATE PET/CT was performed in 4 out of 17 patients; both studies were performed within 1 week of each other. Both studies were interpreted blindly without the knowledge of other imaging findings. The image findings were compared with the results of histopathological examinations and clinical follow-ups.

RESULTS

The 18F-OC PET/CT scans were positive in 14 patients. Furthermore, 4 of 14 patients were scanned with both 18F-OC and 68Ga-DOTATATE PET/CT. Both studies were able to localize the tumor in all 4 patients. In total, 14 patients had surgery to remove the lesions. Postsurgical pathological examination confirmed causative tumors in these patients, whose symptoms diminished promptly. Serum phosphate levels normalized, confirming the diagnosis of TIO. 18F-OC PET/CT sensitivity, specificity, and accuracy were 87.5%, 100%, and 88.2% respectively. 18F-OC PET/CT findings affected patient management in 88.2% of cases.

CONCLUSION

18F-OC PET/CT scan is useful in the detection of tumors causing TIO. Further studies with larger patient populations are needed to validate the result.

Prostate Cancer With Neuroendocrine Differentiation Recurring After Treatment With 177Lu-PSMA: A Chance for 177Lu-DOTATATE Therapy?

ABSTRACT

Prostate cancer with NED (neuroendocrine differentiation) may occur in various stages of the disease, which is associated with a poor prognosis and treatment resistance. We present a case of a patient with metastatic castration-resistant prostatic cancer, who was treated with 7 cycles of 177Lu-PSMA and a very good response. Although only few foci with PSMA uptake were remained in the last posttreatment images, PSA levels dramatically began to rise. This raised suspicion for NED, and 68Ga-DOTATATE was done showing sufficient uptake to consider a trial of 177Lu-DOTATATE. The patient reported pain response, and PSA levels dropped after 1 cycle of the treatment.

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.

Peptide Receptor Radionuclide Therapy With 177Lu-DOTATATE for Symptomatic Control of Refractory Carcinoid Syndrome

CONTEXT

Peptide receptor radionuclide therapy (PRRT) with [Lutetium-177-DOTA0-Tyr3]octreotate (177Lu-DOTATATE) results in an increase of progression-free survival and quality of life in patients with progressive, well-differentiated neuroendocrine neoplasms (NENs).

OBJECTIVE

To study the effect of 177Lu-DOTATATE in patients with carcinoid syndrome and radiologically stable or newly diagnosed disease treated solely for the purpose of symptom reduction.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care hospital.

PATIENTS

Twenty-two patients with a metastatic midgut NEN, elevated urinary 5-hydroxyindolacetic acid excretion, and flushing and/or diarrhea despite treatment with a somatostatin analog, without documented disease progression.

INTERVENTION

PRRT with 177Lu-DOTATATE (intended cumulative dose: 29.6 GBq) with a primary aim to reduce symptoms.

RESULTS

After PRRT, mean bowel movement frequency (BMF) decreased from 6.1 ± 3.4 to 4.6 ± 3.6 per day (P = 0.009). Flushes decreased from 4.3 ± 2.9 to 2.4 ± 2.7 flushes per day (P = 0.002). A decrease of BMF of more than 30% occurred in 47% of patients with baseline BMF of 4 or more (n = 17). In patients with ≥2 episodes of flushing a day (n = 15), 67% of patients had more than 50% decrease of daily flushing. A decrease in urinary 5-hydroxyindolacetic acid excretion of more than 30% was seen in 56% of patients. The European Organization for Research and Treatment of Cancer-Core Module diarrhea subscale score showed a trend toward improvement by an average of 16.7 ± 33.3 points (P = 0.11).

CONCLUSION

PRRT with 177Lu-DOTATATE effectively reduced diarrhea and flushing in patients with carcinoid syndrome and can be considered for symptomatic treatment of carcinoid syndrome insufficiently controlled with somatostatin analogs.

Dissecting the target leukocyte subpopulations of clinically relevant inflammation radiopharmaceuticals

BACKGROUND

Leukocyte subtypes bear distinct pro-inflammatory, reparative, and regulatory functions. Imaging inflammation provides information on disease prognosis and may guide therapy, but the cellular basis of the signal remains equivocal. We evaluated leukocyte subtype specificity of characterized clinically relevant inflammation-targeted radiotracers.

METHODS AND RESULTS

Leukocyte populations were purified from blood- and THP-1-derived macrophages were polarized into M1-, reparative M2a-, or M2c-macrophages. In vitro uptake assays were conducted using tracers of enhanced glucose or amino acid metabolism and molecular markers of inflammatory cells. Both 18F-deoxyglucose (18F-FDG) and the labeled amino acid 11C-methionine (11C-MET) displayed higher uptake in neutrophils and monocytes compared to other leukocytes (P = 0.005), and markedly higher accumulation in pro-inflammatory M1-macrophages compared to reparative M2a-macrophages (P < 0.001). Molecular tracers 68Ga-DOTATATE targeting the somatostatin receptor type 2 and 68Ga-pentixafor targeting the chemokine receptor type 4 (CXCR4) exhibited broad uptake by leukocyte subpopulations and polarized macrophages with highest uptake in T-cells/natural killer cells and B-cells compared to neutrophils. Mitochondrial translocator protein (TSPO)-targeted 18F-flutriciclamide selectively accumulated in monocytes and pro-inflammatory M1 macrophages (P < 0.001). Uptake by myocytes and fibroblasts tended to be higher for metabolic radiotracers.

CONCLUSIONS

The different in vitro cellular uptake profiles may allow isolation of distinct phases of the inflammatory pathway with specific inflammation-targeted radiotracers. The pathogenetic cell population in specific inflammatory diseases should be considered in the selection of an appropriate imaging agent.

Rapid Progression After 177Lu-DOTATATE in Patients With Neuroendocrine Tumors

ABSTRACT

Peptide receptor radionuclide therapy (PRRT) is a treatment option for somatostatin receptor-positive, unresectable or metastatic neuroendocrine tumors (NETs). Despite high disease control rates seen with PRRT, a subset of the NET population seems to have a short progression-free interval. We hypothesize that patients with NETs with rapid progression post-PRRT may have mixed low- and high-grade cell populations, and PRRT treats the lower-grade component, allowing the more aggressive high-grade component to progress.We report 7 patients with biopsy-proven NET who received PRRT with 177Lu-DOTATATE at the Stanford Cancer Center who had evidence of progressive disease (PD) on or within 6 months of therapy.All patients had primary pancreatic, metastatic, well-differentiated NET on diagnosis and were heavily pretreated before receiving PRRT. Two patients had PD while on PRRT; 5 had PD within 6 months of completing PRRT. The median time from the last cycle to PD was 3.2 months (range, 1.1-4.6 months). The median progression-free survival was 7.7 months (95% confidence interval, 5.7-9.8 months). Three patients had a repeat biopsy post-PRRT, 2 of which demonstrated higher disease grade compared with their initial pathology. Further evaluation in larger patient cohorts is warranted to elucidate predictive factors of PRRT response/nonresponse to enable better patient selection.

Feasibility and Therapeutic Potential of Combined Peptide Receptor Radionuclide Therapy With Intensive Chemotherapy for Pediatric Patients With Relapsed or Refractory Metastatic Neuroblastoma

BACKGROUND

Recent evidence has demonstrated high expression of somatostatin receptors in neuroblastoma (NB) cells. Because of this, we endeavored to evaluate the diagnostic performance and clinical efficacy of 68Ga-DOTATATE PET/CT and peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE combined with chemotherapy in pediatric NB patients.

PATIENTS AND METHODS

In total, 14 pediatric patients with histopathologically confirmed NB underwent 68Ga-DOTATATE PET/CT. Among them, the patients who were refractory or relapsed after therapy with 131I-MIBG and had intensive uptake of 68Ga-DOTATATE were referred for PRRT using 177Lu-DOTATATE. Treatment response based on follow-up imaging was classified into complete response, partial response, stable disease, and progressive disease. After each cycle of PRRT, laboratory tests were performed for evaluation of hematological, renal, and hepatic toxicities. The CTCAE (Common Terminology Criteria for Adverse Events; version 4.03) was used for grading adverse event. Curie score and International Society of Pediatric Oncology Europe Neuroblastoma score were used for semiquantitative analysis of scans of patients who underwent PRRT. In addition, overall survival was calculated as the time interval between the date of the first cycle and the end of follow-up or death.

RESULTS

Overall, 14 refractory NB children including 7 boys and 7 girls with a median age of 5.5 years (ranged from 4 to 9) underwent 68Ga-DOTATATE PET/CT. PET/CT was positive in 10/14 patients (71.4%), and the median number of detected lesions in positive patients was 2 (range, 1-13). Of 14 patients, 5 patients underwent PRRT, including 3 boys and 2 girls. A total of 19 PRRT cycles and 66.4 GBq 177Lu-DOTATATE were given. Among these 5 patients, 2 showed an initial complete response, which relapsed a few months later, 1 showed a partial response, and 2 showed progressive disease. According to the Kaplan-Meier test, the overall survival was estimated at 14.5 months (95% confidence interval, 8.9-20.1). In evaluation of PRRT-related toxicity according to the CTCAE, 4 patients showed grade 1, and 1 showed grade 2 leukopenia. Two patients showed grade 1, and 2 others showed grade 2 anemia. Two patients showed grade 1, and 3 patients showed grade 2 thrombocytopenia. Serum creatinine in 1 patient increased to grade 1.

CONCLUSIONS

Combination of 177Lu-DOTATATE with chemotherapeutic agents might achieve worthwhile responses with low toxicity, encouraging survival in NB patients who have relapsed or are refractory to conventional therapy, including 131I-MIBG therapy. Imaging with 68Ga-DOTATATE PET/CT in such patients has a relatively high detection efficacy, demonstrating its potential use as an alternative imaging tool to conventional modalities such as 123I/131I-MIBG. However, further well-designed trials are highly warranted.

Long-term hematologic toxicity of 177Lu-octreotate-capecitabine-temozolomide therapy of GEPNET

Thirty-seven patients with advanced gastroenteropancreatic neuroendocrine tumors (GEPNETs) were treated on a prospective phase II single-center study with four cycles of 7.8 GBq 177Lu-octreotate combined with capecitabine and temozolomide chemotherapy (CAPTEM). Each 8-week cycle combined radiopeptide therapy with 14 days of capecitabine (1500 mg/m2) and 5 days of temozolomide (200 mg/m2). The incidence of grade ≥ 3 hematologic toxicity was analyzed. At a median follow-up of 7-years (range 1-10), six (16%) patients developed persistent hematologic toxicity (PHT) (defined as sustained grade ≥ 3 hematologic toxicity beyond 36-months follow-up) and three (8%) developed MDS/AL with a median time-to-event of 46 and 34 months, respectively. The estimated cumulative incidence of MDS/AL was 11% (95% CI: 3.45-24.01). Development of PHT was the only significant risk factor for secondary MDS/AL (RR, 16; 95% CI: 2.53 to 99.55; P < 0.001). The median PFS was 48 months (95% CI: 40.80-55.20), and the median OS was 86 months (95% CI: 56.90-115.13). Twenty-one deaths were recorded, including 13 (62%) due to progressive disease and all 3 (14%) patients with MDS/AL. 177Lu-octreotate CAPTEM therapy for GEPNETs is associated with a risk of long-term hematologic toxicity. The rising cumulative incidence of MDS/AL > 10% mandates the long-term monitoring of treated patients. However, time to onset is unpredictable, and incidence does not correlate with conventional baseline risk factors. Novel methods are required for the stratification of prospective patients based on genetic risk.

68Ga-DOTATATE PET/CT Imaging of Refractory Pituitary Macroadenoma Invading the Orbit

ABSTRACT

In addition to gastroenteropancreatic neuroendocrine neoplasms, a wide variety of tumors express somatostatin receptors. Somatostatin receptor imaging, heavily utilized in neuroendocrine oncology, may also have utility in the diagnosis of other neoplasms and raises the possibility of potential therapeutic options. We describe the case of a 60-year-old man who underwent 68Ga-DOTATATE PET/CT, demonstrating an avid invasive pituitary macroadenoma. This mass was persistent and refractory despite traditional treatment options. Because of the avidity, 177Lu-DOTATATE therapy was offered, although not ultimately performed, demonstrating a potential treatment for challenging cases utilizing the principles of theranostics.

Pre- and postoperative 68 Ga-DOTATOC positron emission tomography for hormone-secreting pituitary neuroendocrine tumours

OBJECTIVES

Somatostatin receptors (SSTRs) are potential targets for detecting pituitary neuroendocrine tumours (PitNETs) that can be visualized effectively with ⁶⁸ Ga-labelled PET tracers. With this study, we have evaluated the diagnostic properties of such a tracer, ⁶⁸ Ga-DOTATOC, in patients with hormone-producing PitNETs before and after surgery.

DESIGN/METHODS

This prospective case-control study presents preoperative positron emission tomography (PET) and histopathological data in 18 patients with somatotroph (n = 8), corticotroph (n = 7) and thyrotroph (n = 3) PitNETs. Patients were scanned pre- and postoperatively with ⁶⁸ Ga-DOTATOC PET. For the postoperative part of the study, patients with gonadotroph tumours (n = 7) were also included. Fifteen pituitary healthy controls underwent the same protocol once. The maximum standard uptake value (SUV_max ) was analysed in manually outlined regions around the tumour in patients and around the pituitary gland in controls. specimens were collected during surgery in subjects for assessment of adenohypophyseal tumour cell type and the SSTR expression.

RESULTS

Thyrotroph tumours showed higher uptake (median SUV_max 41.1; IQR 37.4-60.0) and corticotroph tumours lower uptake (SUV_max 6.8; 2.6-9.3) than normal pituitary gland (SUV_max 13.8; 12.1-15.5). The uptake in somatotroph tumours (SUV_max 15.9; 11.6-19.7) was similar to the uptake in the pituitary gland. There was a strong correlation between SUV_max and SSTR2 expression (r = .75 (P < .01)). In the postoperative evaluation, PET was able to correlate tracer uptake with biochemical cure and noncure in patients with an abnormal postoperative magnetic resonance image and a preoperative tumour uptake SUV_max  > 13.8.

CONCLUSIONS

⁶⁸ Ga-DOTATOC PET can be used to detect thyrotroph tumours in the pre- and postoperative imaging assessment. Corticotroph tumours had a significantly lower uptake compared to the pituitary gland but without a distinct increased tumour uptake the clinical postoperative value is limited.

Patient external dose rate after 177Lu-DOTATATE therapy: factors affecting its decrease and predictive value

Rationale: Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE (oxodotreotide) results in external radiation exposure from the patient. In the PREELU observational prospective study, we determined the equivalent dose rate at 1 m of the patient (EDR-1m) for a period following PRRT. The main objective was to predict which patients could be discharged from the hospital at approximately 3 h after the administration of 177Lu-DOTATATE, i.e. at the end of the infusion of amino-acids according to our PRRT protocol. As presenting no undue risk of radiation exposure for the public, those patients could be treated as outpatients or day patients, rather than inpatients. Methods: We sequentially measured EDR-1m facing the sternum and then the pelvis during 50 PRRT in 24 patients with metastatic neuroendocrine tumours, each 30 minutes after ending administration of Lutathera, over at least 180 minutes. Results: 180 minutes after the administration of ca. 7400 MBq of Lutathera, EDR-1m was <40 µSv/h in all cases, and <25 µSv/h in 32 cases (64%). After an overnight hospital stay, EDR-1m was <25 µSv/h in all cases. The EDR-1m value measured facing the sternum was the greatest in about one-fourth of paired measurements. In patients whose creatinine clearance was >96 mL/min/1.73m2, the EDR-1m was most likely (predictive value=90%) to drop below 25 µSv/h within 180 minutes after the administration of Lutathera. In 16 patients who benefited from several PRRT cycles, the creatinine clearance did not decrease significantly from one cycle to the next, probably due to the kidney protection by the amino-acid infusion. The patients whose EDR-1m dropped below 25 µSv/h at 180 minutes during their first PRRT cycle were unlikely (predictive value= 88%) to decease during the following two years. Conclusion: All patients could have been discharged 3 h after administration according to the criterion EDR-1m <40 µSv/h. Using EDR-1m <25 µSv/h as criterion, an extended hospital stay beyond 3 h would have been necessary in around one-third of the PRRT treatments and could be anticipated based on creatinine clearance ≤96 mL/min/1.73m2. EDR-1m <25 µSv/h at 180 min during the first PRRT yielded a strong predictive value on the patient's survival at two years, a finding that should be confirmed in future studies.

Feasibility and Therapeutic Potential of Peptide Receptor Radionuclide Therapy for High-Grade Gliomas

PURPOSE

This pilot study tested the principle that 177Lu-DOTATATE may be applied to patients with high-grade gliomas (HGGs) that are either inoperable or refractory to the standard conventional treatments and also assessed whether this approach could be a viable therapeutic plan in this dilemma.

METHODS

In this prospective study, 16 subjects experiencing HGGs that were either inoperable or refractory to the standard conventional treatments were included. All the patients checked for somatostatin receptor expression on the tumors. The patients were treated with 1 to 4 cycles of IV 177Lu-DOTATATE. The primary end point was radiological response after peptide receptor radionuclide therapy, and the secondary end point was improved quality of life using Karnofsky Performance Score and Eastern Cooperative Oncology Group score.

RESULTS

In total, 16 subjects (10 males and 6 females) with a mean age of 55.68 ± 13.17 years (26-73 years) participated in the study. Of them, 8 patients were new HGG cases, and 8 patients had recurrent tumors. The participants' responses to treatments were complete remission in 12.5% of (n = 2), partial remission in 31.25% (n = 5), disease stability in 18.7% (n = 3), and disease progression in 37.5% (n = 6). In total, pretreatment and posttreatment Karnofsky Performance Score and Eastern Cooperative Oncology Group scores did not improved (P > 0.05). The patients were followed up from 1 month to 26 months (median, 3 months).

CONCLUSIONS

This preliminary result suggests that peptide receptor radionuclide therapy using 177Lu-DOTATATE may be associated with positive effects in patients with HGGs (grade III-IV). However, this approach should be evaluated in a more homogeneous group of patients with more favorable performance status.