Peptide receptor radionuclide therapy in patients with inoperable meningiomas: our experience and review of the literature

Efficacy and safety of peptide receptor radionuclide therapy with [177Lu]Lu-DOTA-TATE in 15 patients with progressive treatment-refractory meningioma

PURPOSE

There is no evidence-based systemic therapy for patients with progressive meningiomas for whom surgery or external radiotherapy is no longer an option. In this study, the efficacy and safety of peptide receptor radionuclide therapy (PRRT) in patients with progressive, treatment-refractory meningiomas were evaluated.

METHODS

Retrospective analysis of all meningioma patients treated with [¹⁷⁷Lu]Lu-DOTA-TATE from 2000 to 2020 in our centre. Primary outcomes were response according to RANO bidimensional and volumetric criteria and progression-free survival (PFS). Overall survival (OS) and tumour growth rate (TGR) were secondary endpoints. TGR was calculated as the percentage change in surface or volume per month.

RESULTS

Fifteen meningioma patients received [¹⁷⁷Lu]Lu-DOTA-TATE (7.5-29.6 GBq). Prior to PRRT, all patients had received external radiotherapy, and 14 patients had undergone surgery. All WHO grades were included WHO 1 (n=3), WHO 2 (n=5), and WHO 3 (n=6). After PRRT, stable disease was observed in six (40%) patients. The median PFS was 7.8 months with a 6-month PFS rate of 60%. The median OS was 13.6 months with a 12-month OS rate of 60%. All patients had progressive disease prior to PRRT, with an average TGR of 4.6% increase in surface and 14.8% increase in volume per month. After PRRT, TGR declined to 3.1% in surface (p=0.016) and 5.0% in volume (p=0.013) per month.

CONCLUSION

In this cohort of meningioma patients with exhaustion of surgical and radiotherapeutic options and progressive disease, it was shown that PRRT plays a role in controlling tumour growth.

Somatostatin Receptor Theranostics for Refractory Meningiomas

Somatostatin receptor (SSTR)-targeted peptide receptor radionuclide therapy (PRRT) represents a promising approach for treatment-refractory meningiomas progressing after surgery and radiotherapy. The aim of this study was to provide outcomes of patients harboring refractory meningiomas treated by 177Lu-DOTATATE and an overall analysis of progression-free survival at 6 months (PFS-6) of the same relevant studies in the literature. Eight patients with recurrent and progressive WHO grade II meningiomas were treated after multimodal pretreatment with 177Lu-DOTATATE between 2019 and 2022. Primary and secondarily endpoints were progression-free survival at 6-months (PFS-6) and toxicity, respectively. PFS-6 analysis of our case series was compared with other similar relevant studies that included 86 patients treated with either 177Lu-DOTATATE or 90Y-DOTATOC. Our retrospective study showed a PFS-6 of 85.7% for WHO grade II progressive refractory meningiomas. Treatment was clinically and biologically well tolerated. The overall analysis of the previous relevant studies showed a PFS-6 of 89.7% for WHO grade I meningiomas (n = 29); 57.1% for WHO grade II (n = 21); and 0 % for WHO grade III (n = 12). For all grades (n = 86), including unknown grades, PFS-6 was 58.1%. SSTR-targeted PRRT allowed us to achieve prolonged PFS-6 in patients with WHO grade I and II progressive refractory meningiomas, except the most aggressive WHO grade II tumors. Large scale randomized trials are warranted for the better integration of PRRT in the treatment of refractory meningioma into clinical practice guidelines.

The immunohistochemical expression of SSTR2A is an independent prognostic factor in meningioma

The expression of somatostatin receptors in meningioma is well established. First, suggestions of a prognostic impact of SSTRs in meningioma have been made. However, the knowledge is based on few investigations in small cohorts. We recently analyzed the expression of all five known SSTRs in a large cohort of over 700 meningiomas and demonstrated significant correlations with WHO tumor grade and other clinical characteristics. We therefore expanded our dataset and additionally collected information about radiographic tumor recurrence and progression as well as clinically relevant factors (gender, age, extent of resection, WHO grade, tumor location, adjuvant radiotherapy, neurofibromatosis type 2, primary/recurrent tumor) for a comprehensive prognostic multivariate analysis (n = 666). The immunohistochemical expression scores of SSTR1, 2A, 3, 4, and 5 were scored using an intensity distribution score ranging from 0 to 12. For recurrence-free progression analysis, a cutoff at an intensity distribution score of 6 was used. Univariate analysis demonstrated a higher rate of tumor recurrence for increased expression scores for SSTR2A, SSTR3, and SSTR4 (p = 0.0312, p = 0.0351, and p = 0.0390, respectively), while high expression levels of SSTR1 showed less frequent tumor recurrences (p = 0.0012). In the Kaplan-Meier analysis, a higher intensity distribution score showed a favorable prognosis for SSTR1 (p = 0.0158) and an unfavorable prognosis for SSTR2A (0.0143). The negative prognostic impact of higher SSTR2A expression remained a significant factor in the multivariate analysis (RR 1.69, p = 0.0060). We conclude that the expression of SSTR2A has an independent prognostic value regarding meningioma recurrence.

Differences in the expression of SSTR1-5 in meningiomas and its therapeutic potential

Beyond microsurgical resection and radiation therapy, there are currently no established treatment alternatives for meningioma patients. In selected cases, peptide radio receptor therapy (PRRT) can be implemented. For this purpose, a radionuclide is bound to a substance targeting specific receptors in meningiomas. One of them is somatostatin receptor 2, which can be found in most meningiomas. However, other somatostatin receptors (SSTR) exist, but their expressions have only been described in small case series. In this study, we analyzed the expression of SSTR1, 2A, 3, 4, and 5 in a large cohort of meningiomas in order to enable further refinement of this innovative treatment option. Overall, 726 tumor samples were processed into tissue microarrays and stained for SSTR1, 2A, 3, 4, and 5 immunohistochemically. Microscopic evaluation was done with an established semiquantitative score regarding percentual quantification and staining intensity, and results were correlated with clinical data. There was a significant lower rate of SSTR1 expression in meningiomas of male patients. Older age was associated with higher expression of SSTR1, 2A, and 5 and lower scores for SSTR3 and 4. Tumors treated with radiotherapy before resection showed lower rates of SSTR1 and 5 expression, while recurrent meningiomas had lower SSTR1 scores. Tumor tissue from patients suffering from neurofibromatosis type 2 had lower expression scores for SSTR1, 2, and 5. For SSTR3 and 4, NF2 patients showed higher scores than sporadic tumors. Spinal meningiomas had higher scores for SSTR1, 4, and 5 compared tumor location of the skull base and convexity/falx. Overall, higher WHO grade was associated with lower SSTR scores. While all SSTRs were expressed, there are marked differences of SSTR expression between meningioma subgroups. This has the potential to drive the development of more selective PRRT substances with higher treatment efficacy.

Somatostatin Receptor-Targeted Radiopeptide Therapy in Treatment-Refractory Meningioma: Individual Patient Data Meta-analysis

Somatostatin receptor (SSTR)-targeted peptide receptor radionuclide therapy (PRRT) represents a promising approach for treatment-refractory meningiomas. Methods: We performed an individual patient data meta-analysis, including all published data on meningioma patients treated with SSTR-targeted PRRT. The main outcomes were toxicity, response to treatment, progression-free survival (PFS), and overall survival (OS). We applied the Kaplan-Meier method to estimate survival probabilities and report incidence rates per 100 person-years. We applied Cox proportional hazards models to determine the effect of covariates. Results: We screened 537 papers and identified 6 eligible cohort studies. We included a total of 111 patients who had treatment-refractory meningioma and received SSTR-targeted PRRT. Disease control was achieved in 63% of patients. The 6-mo PFS rates were 94%, 48%, and 0% for World Health Organization grades I, II, and III, respectively. The risk of disease progression decreased by 13% per 1,000-MBq increase in the total applied activity. The 1-y OS rates were 88%, 71%, and 52% for World Health Organization grades I, II, and III, respectively. The risk of death decreased by 17% per 1,000-MBq increase in the total applied activity. The main side effects comprised transient hematotoxicity, such as anemia in 22% of patients, leukopenia in 13%, lymphocytopenia in 24%, and thrombocytopenia in 17%. Conclusion: To our knowledge, this individual patient data meta-analysis represents the most comprehensive analysis of the benefits of and adverse events associated with SSTR-targeted PRRT for treatment-refractory meningioma. The treatment was well tolerated, achieved disease control in most cases, and showed promising results regarding PFS and OS.

Peptide Receptor Radionuclide Therapy of Pulmonary Neuroendocrine Neoplasms: a Single-Centre Experience

Purpose

Peptide receptor radionuclide therapy represents a therapeutic option for neuroendocrine neoplasms; to date, experiences with peptide receptor radionuclide therapy of pulmonary neuroendocrine neoplasms are still limited. We report our experience with peptide receptor radionuclide therapy of pulmonary neuroendocrine neoplasm patients.

Materials and Methods

Clinical records of 14 pulmonary neuroendocrine neoplasm patients (7 female and 7 male) who received at least 2 cycles of peptide receptor radionuclide therapy were retrospectively reviewed. Tumoural uptake of somatostatin analogues at pre-treatment imaging was graded as 2 to 3 in all patients. RECIST criteria were used to evaluate response.

Results

No treated patient had significant toxicity. Partial response was found in 3 (21.4%) patients, stable disease in 7 (50%), and progressive disease in 4 (28.6%). A statistically significant difference between disease state at enrolment and after peptide receptor radionuclide therapy was found.

Conclusions

Our data furtherly support peptide receptor radionuclide therapy as a safe and effective treatment of patients affected by pulmonary neuroendocrine neoplasms allowing disease control in about 71% of patients without showing significant toxicity. Other studies are needed to confirm our results.

Clinical Significance of Somatostatin Receptor (SSTR) 2 in Meningioma

Somatostatin receptor (SSTR) 2, widely expressed in meningioma, is a G-protein-coupled receptor and can be activated by somatostatin or its synthetic analogs. SSTR2 is therefore extensively studied as a marker and target for the diagnosis and treatment of meningioma. Accumulating studies have revealed the crucial clinical significance of SSTR2 in meningioma. Summarizing the progress of these studies is urgently needed as it may not only provide novel and better management for patients with meningioma but also indicate the direction of future research. Pertinent literature is reviewed to summarize the recent collective knowledge and understanding of SSTR2’s clinical significance in meningioma in this review. SSTR2 offers novel ideas and approaches in the diagnosis, treatment, and prognostic prediction for meningioma, but more and further studies are required.

Response assessment of somatostatin receptor targeted radioligand therapies for progressive intracranial meningioma

BACKGROUND

 In somatostatin receptor (SSTR) expressing progressive meningioma, peptide receptor radionuclide therapy (PRRT) has shown effect in small clinical series. However, standardized treatment and response assessment protocols are lacking. We present our experience on PPRT with 177Lu-DOTATATE in progressive meningioma with a special emphasis on state-of-the-art response assessment.

METHODS

 Retrospective analysis on PRRT with 177Lu-DOTATATE from 2015 to 2019. Pre- and post-therapy imaging was performed using MRI and 68Ga-DOTATATE-PET for standard bidimensional and volumetric analyses, respectively, following novel RANO guidelines.

RESULTS

 Seven patients with progressive intracranial meningioma (median age 73 years, interquartile range 60-76; 5 WHO II, 2 WHO I; 5 multifocal) received a median of 4 cycles 2 3 4 of PRRT with 177Lu-DOTATATE in eight-week intervals. Three patients did not undergo post-therapy 68Ga-DOTATATE-PET due to early symptomatic progression and subsequent cessation of PRRT. After completion of 4 PRRT cycles volumetric PET imaging showed stable disease in two of four patients. According to bidimensional MRI response assessment, only one patient was stable. Progression free survival at six months was 42.9 %.

CONCLUSION

 In this heterogeneous collective of seven patients with progressive meningioma, 177Lu-DOTATATE therapies showed heterogeneous effectiveness. PET-based volumetric assessment should be used for response assessment in PRRT additionally to bidimensional imaging.

Benign Intracranial Lesions - Radiotherapy: An Overview of Treatment Options, Indications and Therapeutic Results

BACKGROUND

Radiation Therapy (RT) is an established treatment option for benign intracranial lesions. The aim of this study is to display an update on the role of RT concerning the most frequent benign brain lesions and tumors.

METHODS

Published articles about RT and meningiomas, Vestibular Schwannomas (VSs), Pituitary Adenomas (PAs), Arteriovenous Malformations (AVMs) and craniopharyngiomas were reviewed and extracted data were used.

RESULTS

In meningiomas RT is applied as an adjuvant therapy, in case of patientrefusing surgery or in unresectable tumors. The available techniques are External Beam RT (EBRT) and stereotactic ones such as Stereotactic Radiosurgery (SRS), Fractionated Stereotactic RT (FSRT), Intensity Modulated RT (IMRT) and proton-beam therapy. The same indications are considered in PAs, in which SRS and FSRT achieve excellent tumor control rate (92-100%), acceptable hormone remission rates (>50%) and decreased Adverse Radiation Effects (AREs). Upon tumor growth or neurological deterioration, RT emerges as alone or adjuvant treatment against VSs, with SRS, FSRT, EBRT or protonbeam therapy presenting excellent tumor control growth (>90%), facial nerve (84-100%), trigeminal nerve (74-99%) and hearing (>50%) preservation. SRS poses an effective treatment modality of certain AVMs, demonstrating a 3-year obliteration rate of 80%. Lastly, a combination of microsurgery and RT presents equal local control and 5-year survival rate (>90%) but improved toxicity profile compared to total resection in case of craniopharyngiomas.

CONCLUSION

RT comprises an effective treatment modality of benign brain and intracranial lesions. By minimizing its AREs with optimal use, RT projects as a potent tool against such diseases.

Theragnostic Use of Radiolabelled Dota-Peptides in Meningioma: From Clinical Demand to Future Applications

Meningiomas account for approximately 30% of all new diagnoses of intracranial masses. The 2016 World Health Organization's (WHO) classification currently represents the clinical standard for meningioma's grading and prognostic stratification. However, watchful waiting is frequently the chosen treatment option, although this means the absence of a certain histological diagnosis. Consequently, MRI (or less frequently CT) brain imaging currently represents the unique available tool to define diagnosis, grading, and treatment planning in many cases. Nonetheless, these neuroimaging modalities show some limitations, particularly in the evaluation of skull base lesions. The emerging evidence supporting the use of radiolabelled somatostatin receptor analogues (such as dota-peptides) to provide molecular imaging of meningiomas might at least partially overcome these limitations. Moreover, their potential therapeutic usage might enrich the current clinical offering for these patients. Starting from the strengths and weaknesses of structural and functional neuroimaging in meningiomas, in the present article we systematically reviewed the published studies regarding the use of radiolabelled dota-peptides in surgery and radiotherapy planning, in the restaging of treated patients, as well as in peptide-receptor radionuclide therapy of meningioma.

Prevalence of hitherto unknown brain meningioma detected on 68Ga-DOTATATE positron-emission tomography/computed tomography in patients with metastatic neuroendocrine tumor and exploring potential of 177Lu-DOTATATE peptide receptor radionuclide therapy as single-shot treatment approach targeting both tumors

There is a relative paucity of data in the literature regarding the prevalence of meningiomas and their detection in the clinical setting of neuroendocrine tumors (NETs). The primary aim of this study was to study incidentally detected meningiomas (on ⁶⁸Ga-DOTATATE/ ¹⁸F fluorodeoxyglucose positron-emission tomography/computed tomography [¹⁸F-FDG PET/CT]) in metastatic NET patients referred for peptide receptor radionuclide therapy (PRRT). The secondary aims of this study were to evaluate the response rate of these incidentally detected meningiomas following PRRT and determine progression-free survival (PFS) in this group of patients. This was a retrospective analysis of 500 metastatic/advanced NET patients who had undergone ⁶⁸Ga-DOTATATE PET/CT and ¹⁸F-FDG PET/CT before PRRT workup. The case records were searched to identify cases of hitherto unknown meningiomas detected on PET images; subsequently, these patients underwent brain magnetic resonance imaging (MRI) for confirmation of diagnosis. Following ¹⁷⁷Lu-DOTATATE PRRT, posttreatment functional and structural imaging response evaluation of the meningiomas were undertaken by ⁶⁸Ga-DOTATATE PET/CT, MRI, or CT brain, respectively, along with clinical neurological evaluation. The patients were designated as responders and nonresponders based on predefined response assessment criteria. The PFS of these incidentally detected meningiomas following PRRT was estimated using the Kaplan-Meier product-limit method. Twelve NET patients were retrospectively identified with abnormal focal brain uptake on ⁶⁸Ga-DOTATATE PET/CT. Of these, meningiomas were finally diagnosed on brain MRI examination in six patients (M: F =3:3; age range: 30-66 years; and mean age: 45 years), with a prevalence of 1.2%. Standardized uptake value (SUVmax) of meningiomas on ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT ranged from 7.0 to 22.0 (average 17.0) and 10.19-13.70 (mean: 12.10), respectively, and lesion-to-normal brain parenchyma SUVmax ratio ranged from 140 to 400 (mean: 340) and 1.02-1.07 (mean: 1.04), respectively. Of six patients with incidentally detected meningiomas, one patient died within 1 month and five patients received ¹⁷⁷Lu-DOTATATE PRRT, the number of cycles ranging from two to six (average: 4) and cumulative therapeutic dose ranging from 13.28 to 29.97GBq (average dose: 19.86GBq). Follow-up in these patients ranged from 8 to 36 months (mean: 19.4 months) after the first dose of PRRT. Complete disappearance of neurological symptoms was found in two of five patients (40%), partial response in one of five (20%), and worsening of symptoms in two of five patients (40%). The overall "responder" and "nonresponder" of the meningiomas after PRRT were three patients (60%) and two patients (40%), respectively. Two patients (40%) died of advanced NET at the time of analysis of these data. The observed mean PFS of the meningioma lesions following PRRT was 26.25 months (95% confidence interval, 16.65-35.84 months). No major hematological and renal toxicity were documented in any of these patients. To conclude, ⁶⁸Ga-DOTATATE PET/CT imaging is an effective technique for the incidental identification of meningioma in NET patients. Considering the limited therapeutic options in the palliative setting of advanced or metastatic NET patients and morbidity associated with the therapeutic procedures, PRRT could be a promising targeted therapeutic approach for such cases of incidentally detected meningiomas, which is also helpful in stabilizing the disease process without any significant toxicity.

The theranostic promise for Neuroendocrine Tumors in the late 2010s - Where do we stand, where do we go?

More than 25 years after the first peptide receptor radionuclide therapy (PRRT), the concept of somatostatin receptor (SSTR)-directed imaging and therapy for neuroendocrine tumors (NET) is seeing rapidly increasing use. To maximize the full potential of its theranostic promise, efforts in recent years have expanded recommendations in current guidelines and included the evaluation of novel theranostic radiotracers for imaging and treatment of NET. Moreover, the introduction of standardized reporting framework systems may harmonize PET reading, address pitfalls in interpreting SSTR-PET/CT scans and guide the treating physician in selecting PRRT candidates. Notably, the concept of PRRT has also been applied beyond oncology, e.g. for treatment of inflammatory conditions like sarcoidosis. Future perspectives may include the efficacy evaluation of PRRT compared to other common treatment options for NET, novel strategies for closer monitoring of potential side effects, the introduction of novel radiotracers with beneficial pharmacodynamic and kinetic properties or the use of supervised machine learning approaches for outcome prediction. This article reviews how the SSTR-directed theranostic concept is currently applied and also reflects on recent developments that hold promise for the future of theranostics in this context.

Lung Metastases of Intracranial Atypical Meningioma Diagnosed on Posttherapeutic Imaging After 177Lu-DOTATATE Therapy

Meningiomas are typically benign solitary intracranial tumors. Atypical (World Health Organization [WHO] grade II) or malignant/anaplastic (WHO grade III) meningiomas are seldom, and distant metastases occur only in rare exceptions. We present a case of a 54-year-old male patient with atypical (WHO grade II) meningioma who underwent 1 cycle of peptide receptor radionuclide therapy. Previous imaging studies were confined to the head, but posttherapeutic whole-body Lu-DOTATATE scintigraphy revealed thoracic uptake arising from previously undetected pulmonic meningioma metastases. The case highlights the importance of consideration of rare/untypical metastatic sides and the value of radiotracer whole-body imaging in identifying these.

High Expression of Somatostatin Receptors 2A, 3, and 5 in Corticotroph Pituitary Adenoma

The development of somatostatin analogs for the treatment of pituitary Cushing's disease has been based on somatostatin receptor expression analyses of small cohorts of pituitary adenomas. Additionally, the classification of pituitary adenomas has recently changed. To enable progress with this treatment option, we assessed somatostatin receptors in a large cohort of corticotroph and other pituitary adenomas according to the new WHO classification of endocrine tumors. Paraffin-embedded tumor samples of 88 corticotroph pituitary adenomas and 30 nonadenomatous pituitary biopsies were analyzed after processing into tissue microarrays and immunohistochemical staining for SSTR 1, SSTR2A, SSTR3, SSTR4, and SSTR5. For comparison, 159 other noncorticotroph pituitary adenomas were analyzed. SSTR3 expression was higher in corticotroph adenomas compared to PIT-1-positive, gonadotroph, and nonfunctioning pituitary adenomas (p < 0.0001, p = 0.0280, and p < 0.0001, respectively). This was also the case for the expression of SSTR5 (p = 0.0003, p < 0.0001, and p < 0.0001, respectively). SSTR2A expression was higher compared to gonadotroph and nonfunctioning pituitary adenomas (p = 0.0217 and 0.0126, respectively) while PIT-1-positive adenomas showed even higher SSTR2A expression (p < 0.0001). SSTR2A and SSTR5 were both expressed higher in nonadenomatous pituitary biopsies than in pituitary adenomas (p = 0.0126 and p = 0.0008, respectively). There are marked expression differences of SSTR1-5 as well as changes in expression in recurrent disease that need to be addressed when looking for other possible substances for the treatment of Cushing's disease. SSTR2A, SSTR3, and SSTR5 seem to be most suitable biomarkers for a targeted therapy with somatostatin analogs.

PET imaging in patients with meningioma-report of the RANO/PET Group

Meningiomas are the most frequent nonglial primary brain tumors and represent about 30% of brain tumors. Usually, diagnosis and treatment planning are based on neuroimaging using mainly MRI or, rarely, CT. Most common treatment options are neurosurgical resection and radiotherapy (eg, radiosurgery, external fractionated radiotherapy). For follow-up after treatment, a structural imaging technique such as MRI or CT is used. However, these structural imaging modalities have limitations, particularly in terms of tumor delineation as well as diagnosis of posttherapeutic reactive changes. Molecular imaging techniques such as PET can characterize specific metabolic and cellular features which may provide clinically relevant information beyond that obtained from structural MR or CT imaging alone. Currently, the use of PET in meningioma patients is steadily increasing. In the present article, we provide recommendations for the use of PET imaging in the clinical management of meningiomas based on evidence generated from studies being validated by histology or clinical course.

EANO guidelines for the diagnosis and treatment of meningiomas

Although meningiomas are the most common intracranial tumours, the level of evidence to provide recommendations for the diagnosis and treatment of meningiomas is low compared with other tumours such as high-grade gliomas. The meningioma task force of the European Association of Neuro-Oncology (EANO) assessed the scientific literature and composed a framework of the best possible evidence-based recommendations for health professionals. The provisional diagnosis of meningioma is mainly made by MRI. Definitive diagnosis, including histological classification, grading, and molecular profiling, requires a surgical procedure to obtain tumour tissue. Therefore, in many elderly patients, observation is the best therapeutic option. If therapy is deemed necessary, the standard treatment is gross total surgical resection including the involved dura. As an alternative, radiosurgery can be done for small tumours, or fractionated radiotherapy in large or previously treated tumours. Treatment concepts combining surgery and radiosurgery or fractionated radiotherapy, which enable treatment of the complete tumour volume with low morbidity, are being developed. Pharmacotherapy for meningiomas has remained largely experimental. However, antiangiogenic drugs, peptide receptor radionuclide therapy, and targeted agents are promising candidates for future pharmacological approaches to treat refractory meningiomas across all WHO grades.

Somatostatin receptor-targeted radionuclide therapy for progressive meningioma: benefit linked to 68Ga-DOTATATE/-TOC uptake

BACKGROUND

The prognosis of patients with progressive meningioma after failure of surgery and radiotherapy is poor.

METHODS

We retrospectively evaluated the safety and efficacy of somatostatin-receptor (SSTR)-targeted radionuclide therapy (¹⁷⁷Lu-DOTATATE [n = 16], ⁹⁰Y-DOTATOC [n = 3], or both [n = 1]) in patients with progressive, treatment-refractory meningiomas (5 World Health Organization [WHO] grade I, 7 WHO grade II, 8 WHO grade III) and in part multifocal disease (17 of 20 patients).

RESULTS

SSTR radionuclide treatment (median of 3 treatment cycles, median administered dose/cycle 7400 MBq) led to a disease stabilization in 10 of 20 patients for a median time of 17 months. Stratification according to WHO grade showed a median progression-free survival (PFS) of 32.2 months for grade I tumors, 7.2 for grade II, and 2.1 for grade III. PFS at 6 months was 100% for grade I, 57% for grade II, and 0% for grade III. Median overall survival was 17.2 months in WHO grade III patients and not reached for WHO I and II at a median follow-up of 20 months. In the analysis of single meningioma lesions, maximal and mean standardized uptake values in pretherapeutic ⁶⁸Ga-DOTATOC/-TATE PET/CT were significantly higher in those lesions with radiographic stability after 6 months. In line with this, high expression of SSTR via immunohistochemistry was associated with PFS >6 months.

CONCLUSIONS

SSTR-targeted radionuclide treatment has activity in a subset of patients with meningioma. Expression of SSTR via immunohistochemistry or radionuclide uptake might serve as a predictive biomarker for outcome to facilitate individualized treatment optimization in patients with uni- and multifocal meningiomas.

90Y-DOTATOC as a Therapeutic Option for Complex Recurrent or Progressive Meningiomas

The standard treatment of meningiomas is surgery or radiotherapy. Complex, especially recurrent or progressive cases, may exhibit tumor growth involving critical neurovascular structures or diffuse growth, resulting in limited efficacy and higher risk of standard treatment. We evaluated whether somatostatin receptor-targeted radionuclide therapy with (90)Y-DOTATOC may be a therapeutic option.

METHODS

Fifteen patients with recurrent or progressive meningiomas after multimodal pretreatment or unfavorable medical risk profile were treated with systemic (90)Y-DOTATOC. Endpoints were progression-free survival and toxicity.

RESULTS

Usually applied doses were 7,400 MBq/m(2) of (90)Y-DOTATOC in 2 fractions. Mean observation time was 49.7 mo (range, 12-137 mo). Overall median progression-free survival was at least 24 mo. Toxicity was moderate, mostly hematologic (n = 8) and transient.

CONCLUSION

(90)Y-DOTATOC therapy is feasible and may represent a promising second- or third-line option for complex meningiomas, which are progressive or otherwise not treatable with a reasonable risk-benefit ratio.

(68)Ga-DOTANOC PET/CT detection of multiple extracranial localizations in a patient with anaplastic meningioma

We report herein a case of a 65-year-old male with intracranial recurrence of atypical meningioma initially treated with a combination of surgical resection and gamma knife radiotherapy. Afterwards, he underwent a (68)Ga-DOTANOC PET/CT scan in order to evaluate the feasibility of peptide receptor radionuclide therapy (PRRT). The scan identified multiple pulmonary, pleural and lymph node localizations. Histological diagnosis was consistent with intracranial atypical meningioma with diffuse metastatic spread. In our case, we have shown that meningioma with extracranial locations may present high uptake of somatostatin receptor analogues. Among other radionuclides, we believe that (68)Ga-DOTANOC PET/CT may be particularly useful for staging, detection of recurrence, evaluation of disease extension and alternative therapeutic approaches.