Suggested response criteria for phase II antitumor drug studies for neurofibromatosis type 2 related vestibular schwannoma

Tumors of the nervous system and hearing loss: Beyond vestibular schwannomas

Hearing loss is a common side effect of many tumor treatments. However, hearing loss can also occur as a direct result of certain tumors of the nervous system, the most common of which are the vestibular schwannomas (VS). These tumors arise from Schwann cells of the vestibulocochlear nerve and their main cause is the loss of function of NF2, with 95 % of cases being sporadic and 5 % being part of the rare neurofibromatosis type 2 (NF2)-related Schwannomatosis. Genetic variations in NF2 do not fully explain the clinical heterogeneity of VS, and interactions between Schwann cells and their microenvironment appear to be critical for tumor development. Preclinical in vitro and in vivo models of VS are needed to develop prognostic biomarkers and targeted therapies. In addition to VS, other tumors can affect hearing. Meningiomas and other masses in the cerebellopontine angle can compress the vestibulocochlear nerve due to their anatomic proximity. Gliomas can disrupt several neurological functions, including hearing; in fact, glioblastoma multiforme, the most aggressive subtype, may exhibit early symptoms of auditory alterations. Besides, treatments for high-grade tumors, including chemotherapy or radiotherapy, as well as incomplete resections, can induce long-term auditory dysfunction. Because hearing loss can have an irreversible and dramatic impact on quality of life, it should be considered in the clinical management plan of patients with tumors, and monitored throughout the course of the disease.

Bevacizumab Treatment for Patients with NF2-Related Schwannomatosis: A Single Center Experience

(1) Background: NF2-related schwannomatosis, characterized by the development of bilateral vestibular schwannomas, often necessitates varied treatment approaches. Bevacizumab, though widely utilized, demonstrates variable effectiveness on hearing and tumor growth. At the same time, (serious) adverse events have been frequently reported. (2) Methods: A single center retrospective study was conducted, on NF2-related schwannomatosis patients treated with bevacizumab from 2013 to 2023, with the aim to assess treatment-related and clinical outcomes. Outcomes of interest comprised hearing, radiologic response, symptoms, and adverse events. (3) Results: Seventeen patients received 7.5 mg/kg bevacizumab for 7.1 months. Following treatment, 40% of the patients experienced hearing improvement, 53%, stable hearing, and 7%, hearing loss. Vestibular schwannoma regression occurred in 31%, and 69% remained stable. Further symptomatic improvement was reported by 41%, stable symptoms by 47%, and worsened symptoms by 12%. Treatment discontinuation due to adverse events was observed in 29% of cases. Hypertension (82%) and fatigue (29%) were most frequently reported, with no occurrences of grade 4/5 toxicities. (4) Conclusion: Supporting previous studies, bevacizumab demonstrated positive effects on hearing, tumor control, and symptoms in NF2-related schwannomatosis, albeit with common adverse events. Therefore, careful consideration of an appropriate management strategy is warranted.

Imaging as an early biomarker to predict sensitivity to everolimus for progressive NF2-related vestibular schwannoma

PURPOSE

NF2-related schwannomatosis (NF2) is characterized by bilateral vestibular schwannomas (VS) often causing hearing and neurologic deficits, with currently no FDA-approved drug treatment. Pre-clinical studies highlighted the potential of mTORC1 inhibition in delaying schwannoma progression. We conducted a prospective open-label, phase II study of everolimus for progressive VS in NF2 patients and investigated imaging as a potential biomarker predicting effects on growth trajectory.

METHODS

The trial enrolled 12 NF2 patients with progressive VS. Participants received oral everolimus daily for 52 weeks. Brain imaging was obtained quarterly. As primary endpoint, radiographic response (RR) was defined as ≥ 20% decrease in target VS volume. Secondary endpoints included other tumors RR, hearing outcomes, drug safety and quality of life (QOL).

RESULTS

Eight participants completed the trial and four discontinued the drug early due to significant volumetric VS progression. After 52 weeks of treatment, the median annual VS growth rate decreased from 77.2% at baseline to 29.4%. There was no VS RR and 3 of 8 (37.5%) participants had stable disease. Decreased or unchanged VS volume after 3 months of treatment was predictive of stabilization at 12 months. Seven of eight participants had stable hearing during treatment except one with a decline in word recognition score. Ten of twelve participants reported only minimal changes to their QOL scores.

CONCLUSIONS

Volumetric imaging at 3 months can serve as an early biomarker to predict long-term sensitivity to everolimus treatment. Everolimus may represent a safe treatment option to decrease the growth of NF2-related VS in patients who have stable hearing and neurological condition. TRN: NCT01345136 (April 29, 2011).

Phase II trial of icotinib in adult patients with neurofibromatosis type 2 and progressive vestibular schwannoma

OBJECTIVE

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant syndrome associated primarily with bilateral vestibular schwannomas (VSs). Conventional surgical or radiosurgical treatments for VS in NF2 usually result in high risks of hearing loss and facial nerve impairment, while there is no validated medical option to date. This single-institution phase II study evaluated the efficacy and safety of icotinib, an oral epidermal growth factor receptor tyrosine kinase inhibitor, in patients with NF2 and progressive VS.

METHODS

Icotinib was administered daily at 375 mg orally in a continuous 28-day course for up to 12 courses. The primary endpoint of the study was radiographic response assessed by brain MRI using 3D volumetric tumor analysis and defined as a ≥ 20% decrease in VS volume. Hearing function was evaluated as a secondary endpoint, with response defined as a statistically significant increase in word recognition scores.

RESULTS

Ten eligible patients with a mean age of 23.8 years were enrolled. One patient (10%) with bilateral tumors experienced an objective radiographic response (-23.58% and -22.01%). Three (43%) of 7 patients met the hearing response criteria. At 12 months, the estimated progression-free survival was 82.0% (95% CI 42.3%-95.5%) for volumetric progression and 69.2% (95% CI 37.3%-87.2%) for hearing progression. Common mild to moderate adverse events included rash (90%), diarrhea (50%), myalgia (20%), and nausea/gastrointestinal pain (20%).

CONCLUSIONS

Icotinib carries minor toxicity and is associated with radiographic and hearing responses in patients with NF2 and progressive VS.

Response prediction of vestibular schwannoma after gamma-knife radiosurgery using pretreatment dynamic contrast-enhanced MRI: a prospective study

OBJECTIVES

There are few known predictive factors for response to gamma-knife radiosurgery (GKRS) in vestibular schwannoma (VS). We investigated the predictive role of pretreatment dynamic contrast-enhanced (DCE)-MRI parameters regarding the tumor response after GKRS in sporadic VS.

METHODS

This single-center prospective study enrolled participants between April 2017 and February 2019. We performed a volumetric measurement of DCE-MRI-derived parameters before GKRS. The tumor volume was measured in a follow-up MRI. The pharmacokinetic parameters were compared between responders and nonresponders according to 20% or more tumor volume reduction. Stepwise multivariable logistic regression analyses were performed, and the diagnostic performance of DCE-MRI parameters for the prediction of tumor response was evaluated by receiver operating characteristic curve analysis.

RESULTS

Ultimately, 35 participants (21 women, 52 ± 12 years) were included. There were 22 (62.9%) responders with a mean follow-up interval of 30.2 ± 5.7 months. K^trans (0.036 min^-1 vs. 0.057 min^-1, p = .008) and initial area under the time-concentration curve within 90 s (IAUC90) (84.4 vs. 143.6, p = .003) showed significant differences between responders and nonresponders. K^trans (OR = 0.96, p = .021) and IAUC90 (OR = 0.97, p = .004) were significant differentiating variables in each multivariable model with clinical variables for tumor response prediction. K^trans showed a sensitivity of 81.8% and a specificity of 69.2%, and IAUC90 showed a sensitivity of 100% and a specificity of 53.8% for tumor response prediction.

CONCLUSION

DCE-MRI (particularly K^trans and IAUC90) has the potential to be a predictive factor for tumor response in VS after GKRS.

KEY POINTS

•Pretreatment prediction of gamma-knife radiosurgery response in vestibular schwannoma is still challenging. •Dynamic contrast-enhanced MRI could have predictive value for the response of vestibular schwannoma after gamma-knife radiosurgery.

The Effectiveness of Diffusion Tensor Imaging in Determining Radiological Response after Radiosurgery in Patients with Vestibular Schwannoma

BACKGROUND

The effectiveness of Diffusion Tensor Imaging (DTI) in demonstrating functional changes in the tumor in determining the response to treatment after radiosurgery in patients with vestibular schwannoma (VS) is not clear yet.

OBJECTIVE

The study aimed to determine the change in total tumor volume (TTV) in terms of radiological response in patients who had VS and were treated with radiosurgery and investigated the relationship between the TTV, follow-up times and DTI parameters.

METHODS

Thirty-one patients were assessed using DTI and MRI. TTV, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were calculated. Patients were divided into three groups: those who responded to the treatment (group 1) (n=11), those who did not (group 0) (n=9) and those who remained stable (group 2) (n=11).

RESULTS

The mean duration of follow-up was 28.81±14 months. ADC values increased in patients with VS after radiosurgery (p=0.004). There was no statistical difference in the FA values. A significant reduction in TTV after radiosurgery was detected in group 1 (p=0.003). ADC values increased significantly after radiosurgery in group 2 (p=0.04). Although there were no significant differences, ADC values after radiosurgery increased in group 1 and group 0.

CONCLUSIONS

ADC values continuously increase due to radiation damage in the period before the tumor volume shrinks after radiosurgery. We think that it is not appropriate to diagnose inadequate treatment or progression only when TTV is evaluated in terms of response to treatment in the early period after radiosurgery.

Role and mechanism of autophagy-regulating factors in tumorigenesis and drug resistance

A hallmark feature of tumorigenesis is uncontrolled cell division. Autophagy is regulated by more than 30 genes and it is one of several mechanisms by which cells maintain homeostasis. Autophagy promotes cancer progression and drug resistance. Several genes play important roles in autophagy-induced tumorigenesis and drug resistance including Beclin-1, MIF, HMGB1, p53, PTEN, p62, RAC3, SRC3, NF-2, MEG3, LAPTM4B, mTOR, BRAF and c-MYC. These genes alter cell growth, cellular microenvironment and cell division. Mechanisms involved in tumorigenesis and drug resistance include microdeletions, genetic mutations, loss of heterozygosity, hypermethylation, microsatellite instability and translational modifications at a molecular level. Disrupted or altered autophagy has been reported in hematological malignancies like lymphoma, leukemia and myeloma as well as multiple solid organ tumors like colorectal, hepatocellular, gall bladder, pancreatic, gastric and cholangiocarcinoma among many other malignancies. In addition, defects in autophagy also play a role in drug resistance in cancers like osteosarcoma, ovarian and lung carcinomas following treatment with drugs such as doxorubicin, paclitaxel, cisplatin, gemcitabine and etoposide. Therapeutic approaches that modulate autophagy are a novel future direction for cancer drug development that may help to prevent issues with disease progression and overcome drug resistance.

Evaluation of Brainstem Subcortical Auditory Pathways with Diffusion Tensor Imaging After Gamma Knife Radiosurgery in Intracanalicular Vestibular Schwannoma

Objective

To investigate changes in DTI (Diffusion Tensor Imaging) parameters in brainstem subcortical auditory pathways after Gamma Knife Radiosurgery (GKR) in patients with intracanalicular vestibular schwannoma (ICVS) and to analyze the relationship between tumor volume and ADC (apparent diffusion coefficient) and FA (fractional anisotropy) values.

Method

Seventeen patients with ICVS were evaluated before and after GKR. ADC and FA values of the lateral lemniscus (LL) and inferior colliculus (IC) and tumor volume were calculated. Patients who responded to GKR were classified as Group 1 and those who did not respond adequately as Group 2. The relationship between ADC and FA values and changes in tumor volume were analyzed.

Results

Tumor volume significantly decreased after GKR. ADC values obtained from the tumor increased after GKR (p:0.002). There was no significant difference in LL and IC before and after GKR in terms of FA and ADC values (n:17). There was a positive correlation between response to treatment and contralateral LL ADC values after GKR (p=0.005, r:0.652). There was a negative correlation between contralateral IC FA values after GKR and response to treatment (p=0.017, r: -0.568). There was a significant difference between Groups 1 and 2 in regards to contralateral LL ADC (p=0.03) and IC FA values (p=0.017).

Conclusion

Since the cochlear nerve and subcortical auditory pathways have low regeneration potential after nerve damage, ADC and FA changes in LL and IC may be explained with the presence of intracanalicular tumors prior to GKR. Since GKR does not cause additional damage to the subcortical auditory pathways at the brainstem level, we think that GKR is a noninvasive treatment method that can be used safely in patients with ICVS.

Pretreatment ADC predicts tumor control after Gamma Knife radiosurgery in solid vestibular schwannomas

BACKGROUND

Radiosurgery is a well-established treatment for vestibular schwannomas (VSs), but it is often difficult to identify which tumors will respond to treatment. We sought to determine whether pretreatment or posttreatment tumor apparent diffusion coefficient (ADC) values could predict tumor control in patients undergoing Gamma Knife radiosurgery (GKRS) and whether these values could differentiate between cases of pseudoprogression and cases of true progression in the early posttreatment period.

METHODS

We retrospectively identified patients who underwent GKRS for solid VSs between June 2008 and November 2016 and who had a minimum follow-up of 36 months. Pretreatment and posttreatment minimum, mean, and maximum ADC values were measured for the whole tumor volume and were compared between patients with tumor control and those with tumor progression. In patients with early posttreatment tumor enlargement, ADC values were compared between patients with pseudoprogression and those with true progression.

RESULTS

Of the 44 study patients, 34 (77.3%) demonstrated tumor control at final follow-up. Patients with tumor control had higher pretreatment minimum (1.35 vs 1.09; p = 0.008), mean (1.80 vs 1.45; p = 0.004), and maximum (2.41 vs 1.91; p = 0.011) ADC values than patients with tumor progression. ADC values did not differ between patients with pseudoprogression and those with true progression at early posttreatment follow-up.

CONCLUSIONS

ADC values may be helpful in predicting response to GKRS in patients with solid VSs but cannot predict which tumors will undergo pseudoprogression. Patients with higher pretreatment ADC values may be more likely to demonstrate posttreatment tumor control.

A phase 1 trial of the histone deacetylase inhibitor AR-42 in patients with neurofibromatosis type 2-associated tumors and advanced solid malignancies

PURPOSE

Given clinical activity of AR-42, an oral histone deacetylase inhibitor, in hematologic malignancies and preclinical activity in solid tumors, this phase 1 trial investigated the safety and tolerability of AR-42 in patients with advanced solid tumors, including neurofibromatosis type 2-associated meningiomas and schwannomas (NF2). The primary objective was to define the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs). Secondary objectives included determining pharmacokinetics and clinical activity.

METHODS

This phase I trial was an open-label, single-center, dose-escalation study of single-agent AR-42 in primary central nervous system and advanced solid tumors. The study followed a 3 + 3 design with an expansion cohort at the MTD.

RESULTS

Seventeen patients were enrolled with NF2 (n = 5), urothelial carcinoma (n = 3), breast cancer (n = 2), non-NF2-related meningioma (n = 2), carcinoma of unknown primary (n = 2), small cell lung cancer (n = 1), Sertoli cell carcinoma (n = 1), and uveal melanoma (n = 1). The recommended phase II dose is 60 mg three times weekly, for 3 weeks of a 28-day cycle. DLTs included grade 3 thrombocytopenia and grade 4 psychosis. The most common treatment-related adverse events were cytopenias, fatigue, and nausea. The best response was stable disease in 53% of patients (95% CI 26.6-78.7). Median progression-free survival (PFS) was 3.6 months (95% CI 1.2-9.1). Among evaluable patients with NF2 or meningioma (n = 5), median PFS was 9.1 months (95% CI 1.9-not reached).

CONCLUSION

Single-agent AR-42 is safe and well tolerated. Further studies may consider AR-42 in a larger cohort of patients with NF2 or in combination with other agents in advanced solid tumors.

TRIAL REGISTRATION

NCT01129193, registered 5/24/2010.

Current Management of Large Vestibular Schwannomas for NF2 Patients in a National Reference Center

OBJECTIVE

Recently, treatment decision making for large vestibular schwannomas (VS) in patients with neurofibromatosis type 2 (NF2) has become increasingly challenging due to the availability of multiple therapeutic options including surgery, bevacizumab (an anti-VEGF), radiosurgery, and observation; and it often remains an arbitrary decision based on local practices without firm recommendations. Our objective is to discuss the multimodal treatment options for Koos IV VS in a national reference center for NF2.

STUDY DESIGN

Single-institution retrospective cohort study.

METHODS

All NF2 patients with Koos IV VS who visited our center, the National Reference Center for NF2 Rare Disease in Pitié-Salpétrière Hospital of Paris, between January 2016 and December 2018 were included. Clinical charts, radiology, operative reports, and audiograms were reviewed.

RESULTS

Among 54 NF2 patients with Koos IV VS (mean maximum extrameatal diameter: 34 mm; range:17-62 mm), 27 were operated on for 28 VS; 21 were treated with bevacizumab; and six were observed. In the surgical group, VS resections were gross total, near-total, subtotal, or partial in 32%, 25%, 32%, and 11%, respectively; and a good (House-Brackmann grades I-II) facial nerve function was achieved in 81.5% at 1 year. Hearing was preserved in 14%, 78%, and 66% of the surgical (n = 7), bevacizumab (n = 9), and observation (n = 3) patients, respectively.

CONCLUSION

All therapeutic options, including surgery and/or bevacizumab and occasionally observation, should be proposed to NF2 patients with large VS in the setting of dedicated centers. A decision-making tree is proposed for Koos IV VS management based on tumor evolution, hearing and clinical status of the patient, and contralateral VS size.

LEVEL OF EVIDENCE

4, case series study, historically controlled study Laryngoscope, 131:E98-E107, 2021.

Current status and recommendations for imaging in neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis

Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN) are three clinically distinct tumor predisposition syndromes with a shared tendency to develop peripheral and central nervous system neoplasms. Disease expression and complications of NF1, NF2, and SWN are highly variable, necessitating a multidisciplinary approach to care in order to optimize outcomes. This review will discuss the imaging appearance of NF1, NF2, and SWN and highlight the important role that imaging plays in informing management decisions in people with tumors associated with these syndromes. Recent technological advances, including the role of both whole-body and localized imaging strategies, routine anatomic and advanced magnetic resonance (MR) imaging sequences such as diffusion-weighted imaging (DWI) with quantitative apparent diffusion coefficient (ADC) mapping, and metabolic imaging techniques (MR spectroscopy and positron emission testing) are discussed in the context of the diagnosis and management of people with NF1, NF2, and SWN based on the most up-to-date clinical imaging studies.

Efficacy and safety of bevacizumab for vestibular schwannoma in neurofibromatosis type 2: a systematic review and meta-analysis of treatment outcomes

BACKGROUND

Individual evidence suggests that the anti-angiogenic agent bevacizumab may control vestibular schwannoma (VS) growth and promote hearing preservation in patients with neurofibromatosis type 2 (NF2). However, such metadata has yet to be consolidated, as well as its side-effect profile yet to be fully understood. Our aim was to pool systematically-identified metadata in the literature and substantiate the clinical efficacy and safety of bevacizumab with respect to radiographic tumor response, hearing, and treatment outcomes.

METHODS

Searches of seven electronic databases from inception to March 2019 were conducted following PRISMA guidelines. Articles were screened against pre-specified criteria. The incidence of outcomes was then extracted and pooled by random-effects meta-analysis of proportions.

RESULTS

Eight articles reporting 161 NF2 patients with 196 assessable VS met satisfied all criteria. Radiographic response to bevacizumab was partial regression in 41% (95% CI 31-51%), no change in 47% (95% CI 39-55%), and tumor progression in 7% (95% CI 1-15%). In patients with assessable audiometric data, bevacizumab treatment resulted in hearing improvement in 20% (95% CI 9-33%), stability in 69% (95% CI 51-85%) and additional loss in 6% (95% CI 1-15%) Serious bevacizumab toxicity was observed in 17% (95% CI 10-26%). Subsequent surgical intervention was required in 11% (95% CI 2-20%).

CONCLUSIONS

Bevacizumab may arrest both tumor progression and hearing loss in select NF2 patients presenting with VS lesions. However, a considerable proportion of patients are anticipated to experience serious adverse events; correspondingly, judicious use of bevacizumab for symptomatic management of VS in NF2 is recommended.

Association between patient-reported outcomes and objective disease indices in people with NF2

Objective

The association between patient-reported outcomes and currently used clinical trial endpoints, including total vestibular schwannoma (VS) volume and word recognition score (WRS) in neurofibromatosis type 2 (NF2), is not known.

Methods

A prospective observational study enrolling adult patients with NF2 was conducted at a single specialty center. Measures included: NF2 impact on quality of life (NFTI-QOL), short form (SF)-36; total VS volume, WRS; provider- and patient-reported disease severity (ProvSev, PatSev) measured with an institutionally derived multi-item (e.g., symptom burden, age-of-onset, and fatality-risk) and single-item Likert (mild, moderate, severe) scale.

Results

Fifty-one patients were enrolled between June 2014 and August 2017. Mean age was 42.1 ± 18.2 years and 37.3% patients were male. Mean WRS was 74.4 ± 37.3%; mean total VS volume was 4.2 ± 5.2 cc. Additional lesions were common including meningioma (79.2%) and spinal ependymoma (39.6%). Mean NFTI-QOL score was 7.6 ± 4.9 and correlated with responses on the SF-36. NFTI-QOL also correlated well with PatSev (r = 0.63, p < 0.001) and both multi- and single-item ProvSev (r = 0.62, p < 0.001; r = 0.52, p < 0.001, respectively). A weak correlation was observed between NFTI-QOL and WRS (r = -0.34, p = 0.0156). There was no correlation with VS volume (r = 0.23, p = 0.15).

Conclusions

The NFTI-QOL correlated well with multiple measures of disease severity but not commonly accepted endpoints for NF2 clinical trials including total VS volume in this US cohort of patients with NF2. This suggests that the NFTI-QOL captures components of the patient experience not sufficiently represented by objective measures of disease and underscores the important and complementary role of patient-focused measures in therapeutic outcome assessment in people with NF2.

Bevacizumab for Hearing Preservation in Neurofibromatosis Type 2: Emphasis on Patient-Reported Outcomes and Toxicities

Objective

Bevacizumab for hearing preservation in patients with neurofibromatosis type 2 (NF2) is an emerging practice. We set out to characterize the effectiveness and toxicity of bevacizumab in our patient group.

Study Design

Case series with chart review.

Setting

Tertiary referral center.

Subjects and Methods

Seventeen consecutive patients with NF2 received bevacizumab treatment for vestibular schwannomas, including 2 patients treated to maintain cochlear implant performance. Volumetric analysis of serial magnetic resonance imaging scans was used to evaluate radiographic response, and hearing response was evaluated with serial audiograms. Patient-reported outcomes were also assessed, including subjective hearing improvement, changes in tinnitus, vertigo, headaches, ear pain, and improvement in ability to communicate via telephone.

Results

A positive radiographic response occurred in 8 of 17 (47%) patients and the median tumor volume change was a tumor decrease of 19%. A positive hearing response was recorded in 5 of 9 (56%) patients. Two patients had a word recognition score improvement over 40%. There was an approximately 40% improvement in patient-reported outcomes. Primary toxicities included hypertension, proteinuria, dysgeusia, and amenorrhea.

Conclusion

Bevacizumab treatment was followed by hearing improvement in 56% of patients, while decreased tumor volume was noted in 47%. These outcomes agree favorably with prior reported series. There were significant improvements in patient-reported outcomes that have not been described previously.

Effect of lapatinib on meningioma growth in adults with neurofibromatosis type 2

INTRODUCTION

Epidermal growth factor receptors EGFR and ErbB2 are overexpressed in schwannomas and meningiomas. Preclinical and clinical data indicate that lapatinib, an EGFR/ErbB2 inhibitor, has antitumor activity against vestibular schwannomas in neurofibromatosis type 2 (NF2) patients. Its antitumor activity against meningiomas, however, is unknown.

METHODS

We conducted a retrospective review of patients with NF2 and progressive vestibular schwannomas treated on a phase 2 clinical trial with lapatinib (NCT00973739). We included patients with at least one volumetrically measurable meningioma (> 0.5 cm³) who received at least five 28-day courses of treatment. Patients received lapatinib 1500 mg daily. Meningioma response was assessed using 3-dimensional MRI volumetrics. Progressive meningioma growth and response were defined as + 20 and - 20% change in tumor volume from baseline, respectively. Off-treatment was defined as any period > 5 months without lapatinib.

RESULTS

Eight patients (ages: 20-58 years) who met criteria had 17 evaluable meningiomas with a combined volume of 61.35 cc at baseline, 61.17 cc during treatment, and 108.86 cc (+ 77.44% change) off-treatment, p = 0.0033. Median time on-treatment and off-treatment was 15.5 and 16.7 months, respectively. On-treatment mean and median annualized growth rates were 10.67 and 1.32%, respectively. Off-treatment mean and median annualized growth rates were 20.05 and 10.42%, respectively. The best volumetric response was - 26.1% after 23 months on lapatinib. Two tumors increased > 20% volumetrically on-treatment, compared to eight tumors off-treatment.

CONCLUSIONS

These data suggest that lapatinib may have growth-inhibitory effects on meningiomas in NF2 patients, and support prospective studies of lapatinib for NF2 patients with progressive meningiomas.

Vestibular schwannomas: Accuracy of tumor volume estimated by ice cream cone formula using thin-sliced MR images

PURPOSE

We estimated the volume of vestibular schwannomas by an ice cream cone formula using thin-sliced magnetic resonance images (MRI) and compared the estimation accuracy among different estimating formulas and between different models.

METHODS

The study was approved by a local institutional review board. A total of 100 patients with vestibular schwannomas examined by MRI between January 2011 and November 2015 were enrolled retrospectively. Informed consent was waived. Volumes of vestibular schwannomas were estimated by cuboidal, ellipsoidal, and spherical formulas based on a one-component model, and cuboidal, ellipsoidal, Linskey's, and ice cream cone formulas based on a two-component model. The estimated volumes were compared to the volumes measured by planimetry. Intraobserver reproducibility and interobserver agreement was tested. Estimation error, including absolute percentage error (APE) and percentage error (PE), was calculated. Statistical analysis included intraclass correlation coefficient (ICC), linear regression analysis, one-way analysis of variance, and paired t-tests with P < 0.05 considered statistically significant.

RESULTS

Overall tumor size was 4.80 ± 6.8 mL (mean ±standard deviation). All ICCs were no less than 0.992, suggestive of high intraobserver reproducibility and high interobserver agreement. Cuboidal formulas significantly overestimated the tumor volume by a factor of 1.9 to 2.4 (P ≤ 0.001). The one-component ellipsoidal and spherical formulas overestimated the tumor volume with an APE of 20.3% and 29.2%, respectively. The two-component ice cream cone method, and ellipsoidal and Linskey's formulas significantly reduced the APE to 11.0%, 10.1%, and 12.5%, respectively (all P < 0.001).

CONCLUSION

The ice cream cone method and other two-component formulas including the ellipsoidal and Linskey's formulas allow for estimation of vestibular schwannoma volume more accurately than all one-component formulas.

Pretreatment ADC Values Predict Response to Radiosurgery in Vestibular Schwannomas

BACKGROUND AND PURPOSE

The response rate of vestibular schwannomas to radiation therapy is variable, and there are surgical options available in the event of treatment failure. The aim of this study was to determine whether pre- and posttreatment ADC values can predict the tumor response to radiation therapy.

MATERIALS AND METHODS

From a data base of 162 patients with vestibular schwannomas who underwent radiation therapy with gamma knife, CyberKnife, or fractionated stereotactic radiation therapy as the first-line therapy between January 2003 and December 2013, we found 20 patients who had pretreatment ADC values. There were 108 patients (including these 20) had serial MR images that included DWI allowing calculated ADC values from 2-132 months after radiation therapy. Two reviewers measured the mean, minimum, and maximum ADC values from elliptical ROIs that included tumor tissue only. Treatment responders were defined as those with a tumor total volume shrinkage of 20% or more after radiation therapy.

RESULTS

The pretreatment mean minimum ADC for nonresponders was 986.7 × 10^-6 mm²/s (range, 844-1230 × 10^-6 mm²/s) and it was 669.2 × 10^-6 mm²/s (range, 345-883 × 10^-6 mm²/s) for responders. This difference was statistically significant (P < .001). Using a minimum ADC value of 800 × 10^-6 mm²/s led to the correct classification of 18/20 patients based on pretreatment ADC values. The intraclass correlation between reviewers was 0.61. No posttreatment ADC values predicted response.

CONCLUSIONS

Pretreatment ADC values of vestibular schwannomas are lower in responders than nonresponders. Using a minimum ADC value of 800 × 10^-6 mm²/s correctly classified 90% of cases.

Neurofibromatosis Type 2

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder (incidence 1:33 000-40 000) characterized by formation of central nervous system tumors, due to mutation in the NF2 gene on chromosome 22q12. Vestibular schwannomas are the hallmark lesion, affecting 95% of individuals and typically occur bilaterally. Schwannomas commonly occur on other nerves intracranially and in the spinal compartment, along with meningiomas, ependymomas, and gliomas. Although histologically benign, tumors are associated with significant morbidity due to multiple problems including hearing and vision loss, gait abnormalities, paralysis, pain, and seizures. Risk of early mortality from brainstem compression and other complications is significant. Severity of disease is higher when NF2 presents during childhood. Children have a more variable presentation, which can be associated with significant delays in recognition of the condition. Careful examination of the skin and eyes can identify important clinical signs of NF2 during childhood, allowing timely initiation of disease-specific surveillance and treatment. Monitoring for complications comprises clinical evaluation, along with functional testing including audiology and serial neuroimaging, which together inform decisions regarding treatment. Evidence for disease-specific medical treatment options is increasing, nevertheless most patients will benefit from multimodal treatment including surgery during their lifetime. Patient enrolment in international natural history and treatment trials offers the best opportunity to accelerate our understanding of the complications and optimal treatment of NF2, with a view to improving outcomes for all affected individuals.

Mechanism-based modeling of the clinical effects of bevacizumab and everolimus on vestibular schwannomas of patients with neurofibromatosis type 2

PURPOSE

To describe the natural growth of vestibular schwannoma in patients with neurofibromatosis type 2 and to predict tumor volume evolution in patients treated with bevacizumab and everolimus.

METHODS

Clinical data, including longitudinal tumor volumes in patients treated by bevacizumab (n = 13), everolimus (n = 7) or both (n = 2), were analyzed by means of mathematical modeling techniques. Together with clinical data, data from the literature were also integrated to account for drugs mechanisms of action.

RESULTS

We developed a model of vestibular schwannoma growth that takes into account the effect of vascular endothelial growth factors and mammalian target of rapamycin complex 1 on tumor growth. Behaviors, such as tumor growth rebound following everolimus treatment stops, was correctly described with the model. Preliminary results indicate that the model can be used to predict, based on early tumor volume dynamic, tumor response to variation in treatment dose and regimen.

CONCLUSION

The developed model successfully describes tumor volume growth before and during bevacizumab and/or everolimus treatment. It might constitute a rational tool to predict patients' response to these drugs, thus potentially improving management of this disease.

Efficacy and Biomarker Study of Bevacizumab for Hearing Loss Resulting From Neurofibromatosis Type 2-Associated Vestibular Schwannomas

PURPOSE

Neurofibromatosis type 2 (NF2) is a tumor predisposition syndrome characterized by bilateral vestibular schwannomas (VSs) resulting in deafness and brainstem compression. This study evaluated efficacy and biomarkers of bevacizumab activity for NF2-associated progressive and symptomatic VSs.

PATIENTS AND METHODS

Bevacizumab 7.5 mg/kg was administered every 3 weeks for 46 weeks, followed by 24 weeks of surveillance after treatment with the drug. The primary end point was hearing response defined by word recognition score (WRS). Secondary end points included toxicity, tolerability, imaging response using volumetric magnetic resonance imaging analysis, durability of response, and imaging and blood biomarkers.

RESULTS

Fourteen patients (estimated to yield > 90% power to detect an alternative response rate of 50% at alpha level of 0.05) with NF2, with a median age of 30 years (range, 14 to 79 years) and progressive hearing loss in the target ear (median baseline WRS, 60%; range 13% to 82%), were enrolled. The primary end point, confirmed hearing response (improvement maintained ≥ 3 months), occurred in five (36%) of 14 patients (95% CI, 13% to 65%; P < .001). Eight (57%) of 14 patients had transient hearing improvement above the 95% CI for WRS. No patients experienced hearing decline. Radiographic response was seen in six (43%) of 14 target VSs. Three grade 3 adverse events, hypertension (n = 2) and immune-mediated thrombocytopenic purpura (n = 1), were possibly related to bevacizumab. Bevacizumab treatment was associated with decreased free vascular endothelial growth factor (not bound to bevacizumab) and increased placental growth factor in plasma. Hearing responses were inversely associated with baseline plasma hepatocyte growth factor (P = .019). Imaging responses were associated with high baseline tumor vessel permeability and elevated blood levels of vascular endothelial growth factor D and stromal cell-derived factor 1α (P = .037 and .025, respectively).

CONCLUSION

Bevacizumab treatment resulted in durable hearing response in 36% of patients with NF2 and confirmed progressive VS-associated hearing loss. Imaging and plasma biomarkers showed promising associations with response that should be validated in larger studies.

Bevacizumab Treatment for Vestibular Schwannoma in a Patient with Neurofibromatosis Type 2: Hearing Improvement and Tumor Shrinkage

Purpose

Neurofibromatosis type 2 (NF2) is a dominantly inherited genetic condition that clinically manifests through the appearance of multiple meningiomas, ependymomas and bilateral vestibular schwannomas (acoustic neuromas) which lead to progressive hearing loss. Neovascularization is necessary for tumor growth and is driven by tumor-produced angiogenic factors such as vascular endothelial growth factor (VEGF). Bevacizumab is a humanized monoclonal antibody that neutralizes the activity of VEGF. Recent data have shown that VEGF is produced by schwannoma tumor cells. Bevacizumab treatment in patients with NF2 who were considered poor candidates for surgery and radiation therapy was found to result in clinically meaningful hearing improvement and tumor volume reduction in previous studies.

Methods

We report the case of a 40-year-old woman with sudden right-sided hearing loss. Magnetic resonance imaging (MRI) revealed multiple meningiomas and neurinomas (C2 and L5 lesions) and a right-sided acoustic neurinoma, confirming the diagnosis of NF2. Bevacizumab was given as infusion every 2 weeks at a dose of 5.0 mg/kg body weight with MRI monitoring every 6 months.

Results

After 6 months from the start of therapy the patient reported progressive improvement of hearing response in audiometry, word recognition and face-to-face conversation. MRI evidenced reduction of the volume of the right vestibular schwannoma and the multiple meningiomas as well as attenuation of brain stem compression.

Conclusions

At the time of writing the patient is continuing treatment with bevacizumab without adverse events. She has good functional status and quality of life.

Bevacizumab decreases vestibular schwannomas growth rate in children and teenagers with neurofibromatosis type 2

Vestibular schwannoma (VS) growth in neurofibromatosis type 2 (NF2) can be responsible for brainstem compression and hearing loss. Surgical removal remains the standard therapy despite potential morbidity. Previous studies suggested that the inhibition of the VEGF-pathway with bevacizumab could result in hearing improvement, reduction of the tumor volume or both in adults. We retrospectively describe the French experience of bevacizumab treatment delivered for progressive VS in pediatric NF2 patients. Patients received Bevacizumab 5 or 10 mg/kg every 2 weeks according to the physician's choice. Follow-up included clinical assessment, audiometry and volumetric MRI every 3-6 months. Seven patients harboring 11 VS were included. The median age at inclusion was 15 years (11.4-18.8), and the median treatment duration was 11.3 months (3.2-55.6). At baseline, the median tumor volume was 1.2 cm(3) (0.52-13.5) and the median word recognition score was 90 % (0-100). We observed one major response, two minor responses and a decrease in the rate of tumor growth for the 4 other patients. The median annual growth rate before treatment was significantly higher than after 1 year of treatment (138 vs. 36 %, n = 5, p = 0.043). We noted one hearing improvement over the course of 1 year under treatment (hearing response rate was 14 %). Overall, the treatment was well tolerated. Our study supports that bevacizumab is an attractive therapeutic option for pediatric NF2 patients with growing VS. Thorough multidisciplinary evaluation is necessary to identify the best candidates prior to treatment. It is likely that a better functional outcome would be expected if targeted therapies were discussed early in the management of the disease.

Reduced dosage of bevacizumab in treatment of vestibular schwannomas in patients with neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome associated with vestibular schwannomas and other benign tumors of the central nervous system. Bevacizumab is used for treatment of progressive vestibular schwannomas, with the intent to reduce tumor size or preserve/improve hearing. Prolonged treatment can cause side effects such as hypertension and proteinuria, which can be cause for discontinuation of therapy. We report on 3 patients who were treated with bevacizumab for 66-76 months, with dose reductions that minimized side effects while sustaining the clinical effect of the antiangiogenic therapy. After dose reduction from 5 mg/kg bi- or tri-weekly to 2.5 mg bi- or tri-weekly, all patients appeared clinically stable and radiographic and audiologic follow-up showed sustained response. In conclusion, in some NF2 patients, dose reduction of bevacizumab seems to be an effective option for managing side effects.

The effect of bevacizumab on vestibular schwannoma tumour size and hearing in patients with neurofibromatosis type 2

The hallmark of neurofibromatosis type 2 (NF2) is bilateral vestibular schwannomas (VS) and severe hearing loss is common in NF2 patients. Vascular endothelial growth factor (VEGF) expression level in NF2 correlates with tumour growth rate and bevacizumab, a VEGF-binding antibody, has previously been shown to induce tumour shrinkage and improve hearing. We retrospectively reviewed the effect of bevacizumab on hearing and VS tumour size in 12 consecutive NF2 patients. Bevacizumab 10 mg/kg was administered intravenously every second week for 6 months; hereafter, bevacizumab 15 mg/kg was administered every third week. Patients were evaluated with repeated audiometries, MR scans and clinical evaluations. Radiological response was defined as a 20 % or greater reduction in VS volume. A total of 398 treatments (median 36) were administered and the median duration on therapy was 22 months (range 7-34). We observed a radiological response (≥20 % tumour shrinkage) in seven out of 18 tumours (39 %) in six out of 12 patients (50 %). Sustained radiological responses were maintained in six tumours (33 %) for more than 2 months. Three patients had objectively improved hearing and five patients reported subjective benefit in neurological symptoms, including improved hearing. Toxicity was in general manageable; however, one patient died from cerebral haemorrhage which was possibly related to therapy. In conclusion, bevacizumab improved hearing and reduced the size of VS in some patients with progressive NF2 which corroborates previous findings; however, the risk of severe side effects should be carefully considered and discussed with the patients prior to treatment.

Identifying predictors of early growth response and adverse radiation effects of vestibular schwannomas to radiosurgery

PURPOSE

To determine whether pre-treatment growth rate of vestibular schwannomas (VS) predict response to radiosurgery.

METHODS

A retrospective review of a prospectively maintained database of all VS patients treated with 12Gy prescription dose between September 2005 and June 2011 at our institution using the Leksell Model 4C Gamma Knife Unit was conducted. Patients who had a minimum of 12-months clinical and radiological assessment before and after radiosurgery were included in this study. Tumor growth rates were calculated using specific growth rate (SGR). Tumor volumes were measured on FIESTA-MRI scans using ITK-SNAP v2.2.

RESULTS

Following radiosurgery, twenty-seven (42.9%) patients showed a significant decrease in volume after one year, twenty-nine (46.0%) stabilized, and seven (11.1%) continued to grow. There was no correlation between VS pre-treatment SGRs with post-treatment SGRs (p = 0.34), and incidence of adverse radiation effects (ARE). The reduction in tumors' SGRs after radiosurgery was proportional to pre-treatment SGRs, although this correlation was not statistically significant (p = 0.19). Analysis of risk factors revealed a positive correlation between post-treatment SGRs and incidence of non-auditory complications, most of which were attributed to ARE (p = 0.047).

CONCLUSION

Pre-treatment growth rate of VS does not predict tumor response to radiosurgery or incidence of ARE. VS with higher SGRs post-radiosurgery are more likely to experience ARE.

Natural history of vestibular schwannoma growth and hearing decline in newly diagnosed neurofibromatosis type 2 patients

OBJECTIVE

To determine the rate of growth in vestibular schwannomas and the rate of hearing decline in neurofibromatosis type 2 (NF2) patients not undergoing active treatment

STUDY DESIGN

Prospective study.

SETTING

Data were collected at 10 NF2 centers, including hospital-based, academic, and tertiary care centers.

PATIENTS

120 NF2 patients with 200 vestibular schwannomas.

OUTCOME MEASURES

Hearing decline, defined as a decrease in word recognition score outside the 95% critical difference compared with baseline, and radiographic progression, defined as a 20% or greater increase in tumor volume compared with baseline.

RESULTS

During a total of 313.4 patient-years of follow-up, the rate of hearing decline was 5% at 1 year, 13% at 2 years, and 16% at 3 years; the rate of tumor progression was 31% at 1 year, 64% at 2 years, and 79% at 3 years. For this cohort, the median time to tumor progression (14 mo) was significantly shorter than the median time to hearing decline (62.0 mo).

CONCLUSION

These data provide potentially useful information for the design of clinical trials for NF2 vestibular schwannoma.

Phase II study of everolimus in children and adults with neurofibromatosis type 2 and progressive vestibular schwannomas

BACKGROUND

Activation of the mammalian target of rapamycin (mTOR) signaling pathway is thought to be a key driver of tumor growth in Merlin (NF2)-deficient tumors. Everolimus is an oral inhibitor of mTOR complex 1 (mTORC1) with antitumor activity in a variety of cancers.

METHODS

We conducted a single-institution, prospective, 2-stage, open-label phase II study to estimate the response rate to everolimus in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Ten eligible patients were enrolled, including 2 pediatric patients. Everolimus was administered at a daily dose of 10 mg (adults) or 5 mg/m(2)/day (children <18 y) orally in continuous 28-day courses, for up to 12 courses. Response was assessed every 3 months with MRI, using 3-dimensional volumetric tumor analysis, and audiograms. Nine patients were evaluable for the primary response, defined as ≥15% decrease in VS volume. Hearing response was evaluable as a secondary endpoint in 8 patients.

RESULTS

None of the 9 patients with evaluable disease experienced a clinical or MRI response. No objective imaging or hearing responses were observed in stage 1 of the trial, and the study was closed according to predefined stopping rules.

CONCLUSION

Everolimus is ineffective for the treatment of progressive VS in NF2 patients. We are currently conducting a pharmacokinetic/pharmacodynamic ("phase 0") study of everolimus in presurgical VS patients to elucidate the biological basis for apparent treatment resistance to mTORC1 inhibition in these tumors.

Recommendations for imaging tumor response in neurofibromatosis clinical trials

OBJECTIVE

Neurofibromatosis (NF)-related benign tumors such as plexiform neurofibromas (PN) and vestibular schwannomas (VS) can cause substantial morbidity. Clinical trials directed at these tumors have become available. Due to differences in disease manifestations and the natural history of NF-related tumors, response criteria used for solid cancers (1-dimensional/RECIST [Response Evaluation Criteria in Solid Tumors] and bidimensional/World Health Organization) have limited applicability. No standardized response criteria for benign NF tumors exist. The goal of the Tumor Measurement Working Group of the REiNS (Response Evaluation in Neurofibromatosis and Schwannomatosis) committee is to propose consensus guidelines for the evaluation of imaging response in clinical trials for NF tumors.

METHODS

Currently used imaging endpoints, designs of NF clinical trials, and knowledge of the natural history of NF-related tumors, in particular PN and VS, were reviewed. Consensus recommendations for response evaluation for future studies were developed based on this review and the expertise of group members.

RESULTS

MRI with volumetric analysis is recommended to sensitively and reproducibly evaluate changes in tumor size in clinical trials. Volumetric analysis requires adherence to specific imaging recommendations. A 20% volume change was chosen to indicate a decrease or increase in tumor size. Use of these criteria in future trials will enable meaningful comparison of results across studies.

CONCLUSIONS

The proposed imaging response evaluation guidelines, along with validated clinical outcome measures, will maximize the ability to identify potentially active agents for patients with NF and benign tumors.

Challenges relating to solid tumour brain metastases in clinical trials, part 1: patient population, response, and progression. A report from the RANO group

Therapeutic outcomes for patients with brain metastases need to improve. A critical review of trials specifically addressing brain metastases shows key issues that could prevent acceptance of results by regulatory agencies, including enrolment of heterogeneous groups of patients and varying definitions of clinical endpoints. Considerations specific to disease, modality, and treatment are not consistently addressed. Additionally, the schedule of CNS imaging and consequences of detection of new or progressive brain metastases in trials mainly exploring the extra-CNS activity of systemic drugs are highly variable. The Response Assessment in Neuro-Oncology (RANO) working group is an independent, international, collaborative effort to improve the design of trials in patients with brain tumours. In this two-part series, we review the state of clinical trials of brain metastases and suggest a consensus recommendation for the development of criteria for future clinical trials.

Optimizing biologically targeted clinical trials for neurofibromatosis

INTRODUCTION

The neurofibromatoses (neurofibromatosis type 1, NF1 and neurofibromatosis type 2, NF2) comprise the most common inherited conditions in which affected children and adults develop tumors of the central and peripheral nervous system. In this review, the authors discuss how the establishment of the Neurofibromatosis Clinical Trials Consortium (NFCTC) has positively impacted on the design and execution of treatment studies for individuals with NF1 and NF2.

AREAS COVERED

Using an extensive PUBMED search in collaboration with select NFCTC members expert in distinct NF topics, the authors discuss the clinical features of NF1 and NF2, the molecular biology of the NF1 and NF2 genes, the development and application of clinically relevant Nf1 and Nf2 genetically engineered mouse models and the formation of the NFCTC to enable efficient clinical trial design and execution.

EXPERT OPINION

The NFCTC has resulted in a more seamless integration of mouse preclinical and human clinical trials efforts. Leveraging emerging enabling resources, current research is focused on identifying subtypes of tumors in NF1 and NF2 to deliver the most active compounds to the patients most likely to respond to the targeted therapy.

Bevacizumab for progressive vestibular schwannoma in neurofibromatosis type 2: a retrospective review of 31 patients

OBJECTIVE

Early studies suggest that bevacizumab treatment can result in tumor shrinkage and hearing improvement for some patients with neurofibromatosis type 2 (NF2). The aim of this study was to report extended follow-up in a larger cohort of similarly treated patients.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center

PATIENTS

Thirty-one consecutive NF2 patients who received bevacizumab for progressive vestibular schwannomas.

MAIN OUTCOME MEASURE

Hearing improvement, defined as an improvement in word recognition score above the 95% critical difference compared with baseline, and radiographic response, defined as a 20% or greater decrease in tumor volume compared with baseline.

RESULTS

The median age was 26 years (range, 12-73 yr). The median volumetric tumor growth rate before treatment was 64% per year. At the time of analysis, the median duration of treatment was 14 months (range, 6-41 mo) with a total of 47 patient-years of follow-up. A hearing response occurred in 57% (13/23) of evaluable patients and a radiographic response in 55% (17/31) of target vestibular schwannomas. The median time to response was 3 months for both end points. The only clinical or radiographic feature at baseline that correlated with change in tumor volume at 3 months was the mean apparent diffusion coefficient value, a radiologic marker of edema (p = 0.036). Ninety percent of patients had stable or improved hearing after 1 year of treatment and 61% at 3 years; 88% of patients had stable or decreased tumor size after 1 year of treatment and 54% at 3 years. Overall, treatment was well tolerated.

CONCLUSION

Bevacizumab treatment was followed by hearing improvement and tumor shrinkage in more than 50% of progressive vestibular schwannomas in NF2 patients. Stable or improved hearing was retained in the majority of patients.

Phase II trial of lapatinib in adult and pediatric patients with neurofibromatosis type 2 and progressive vestibular schwannomas

This single-institution phase II study was performed to estimate the response rate to lapatinib in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Twenty-one eligible patients were enrolled. Brain and spine MRIs, including 3-dimensional volumetric tumor analysis, and audiograms were performed once at baseline and again every 12 weeks. The primary response end point was evaluable in 17 patients and defined as ≥15% decrease in VS volume. Hearing was evaluable as a secondary end point in 13 patients, with responses defined as an improvement in the pure tone average of at least 10 dB  or a statistically significant increase in word recognition scores. Four of 17 evaluable patients experienced an objective volumetric response (23.5%; 95% confidence interval [CI], 10%-47%), with median time to response of 4.5 months (range, 3-12). In responders, reduction in VS volumes ranged from -15.7% to -23.9%. Four of 13 patients evaluable for hearing met hearing criteria for response (30.8%; 95% CI, 13%-58%). One sustained response exceeded 9 months in duration. Median time to overall progression (ie, volumetric progression or hearing loss) was 14 months. The estimated overall progression-free survival and volumetric progression-free survival at 12 months were 64.2% (95% CI, 36.9%-82.1%) and 70.6% (95% CI, 43.1%-86.6%), respectively. Toxicity was generally minor, and no permanent dose modifications were required. Lapatinib carries minor toxicity and has objective activity in NF2 patients with progressive VS, including volumetric and hearing responses. Future studies could explore combination therapy with other molecular targeted agents such as bevacizumab.

Consensus recommendations for current treatments and accelerating clinical trials for patients with neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome characterized by bilateral vestibular schwannomas (VS) which often result in deafness despite aggressive management. Meningiomas, ependymomas, and other cranial nerve and peripheral schwannomas are also commonly found in NF2 and collectively lead to major neurologic morbidity and mortality. Traditionally, the overall survival rate in patients with NF2 is estimated to be 38% at 20 years from diagnosis. Hence, there is a desperate need for new, effective therapies. Recent progress in understanding the molecular basis of NF2 related tumors has aided in the identification of potential therapeutic targets and emerging clinical therapies. In June 2010, representatives of the international NF2 research and clinical community convened under the leadership of Drs. D. Gareth Evans (University of Manchester) and Marco Giovannini (House Research Institute) to review the state of NF2 treatment and clinical trials. This manuscript summarizes the expert opinions about current treatments for NF2 associated tumors and recommendations for advancing therapies emerging from that meeting. The development of effective therapies for NF2 associated tumors has the potential for significant clinical advancement not only for patients with NF2 but for thousands of neuro-oncology patients afflicted with these tumors.

Therapeutics for childhood neurofibromatosis type 1 and type 2

OPINION STATEMENT

Neurofibromatosis type 1 (NF1) and type 2 (NF2) are genetically and medically distinct neurocutaneous disorders that are both associated with tumors affecting the central and peripheral nervous systems. NF1 has a frequency of 1 in 3,000, compared with 1 in 30,000 for NF2. Careful surveillance is important for both conditions, to allow early identification and treatment of complications. The most common and important problems in NF1 are cognitive impairment, optic pathway gliomas, plexiform neurofibromas, and orthopaedic issues. Early intervention and tailored educational programs are indicated for learning difficulties. Attention deficit hyperactivity disorder may be amenable to treatment with stimulant medication. A clinical trial is under way to evaluate lovastatin in the treatment of cognitive problems in children with NF1. Chemotherapy with vincristine and carboplatin is the current standard of care for symptomatic optic pathway gliomas, but new agents with improved efficacy are needed. Plexiform neurofibromas may be treated with surgery, but often recur. To date, no medical therapy has proven effective in limiting plexiform neurofibroma growth, but several candidate medications are under consideration in clinical trials. Malignant peripheral nerve sheath tumors may arise in preexisting plexiform neurofibromas, so changes in tumor growth or an increase in pain or focal neurologic deficit should prompt further investigation and early treatment with wide surgical resection, with or without adjuvant chemotherapy or radiotherapy. Specialist surgical intervention may be needed for scoliosis and tibial pseudoarthrosis. In NF2, surgical treatment remains a cornerstone of management for symptomatic progressive vestibular schwannomas, meningiomas, and spinal tumors. Vascular endothelial growth factor inhibitors show promise for the treatment of vestibular schwannomas, with the aim of delaying surgery, and other targeted molecular therapies are becoming available as investigational options. Hearing aids and brainstem and cochlear implants have a role in optimizing functional hearing in some patients. Specialist ophthalmology input should be arranged to monitor for ophthalmologic complications. A coordinated effort is needed to enroll NF1 and NF2 patients in international multicenter clinical trials of promising new pharmacologic agents. Genetic testing is useful for prenatal diagnosis and may be important in understanding individual responses to novel medical therapies in the future. Effective transition to adult services is important, considering the likelihood of further complications in the adult years.

Tumor pseudoprogression following radiosurgery for vestibular schwannoma

We sought to characterize vestibular schwannoma (VS) pseudoprogression after radiosurgery to assess its incidence, causative factors, and association with radiation-induced adverse effects. We performed a retrospective study of VS treated with Gamma Knife radiosurgery during 2005-2009. Seventy-five patients had at least 24 months of clinical and radiographic follow-up (median, 29 months) and were included. Tumor response was calculated volumetrically using Gamma plan software on consecutive MRIs. All treatment plans were reviewed for dosimetry characteristics. Forty-nine VS (65%) were stable or regressed after treatment. Seventeen (23%) underwent pseudoprogression, with onset of enlargement at 6 months. Seven (9%) remained larger than initial treatment volume at last follow-up. Nine (12%) had persistent growth. Three patients underwent subsequent microsurgery. One patient required intervention at 3 months for cystic enlargement; otherwise, all patients with progressive enlargement had stable VS until at least 24 months. Twenty-six patients (34.7%) developed nonauditory adverse radiation effects after treatment, including cranial neuropathy, ataxia, and hydrocephalus. There was no statistical association between onset of clinical deterioration and tumor response. Volume changes in the first 24 months after radiosurgery rarely herald treatment failure. Any volume change after 24 months is indicative of treatment failure. Pseudoprogression does not appear to be independently linked to radiation-induced morbidity, and there are no patient-related or radiosurgical parameters that predict tumor response.

Response assessment in neuro-oncology

Accuracy and reproducibility in determining response to therapy and tumor progression can be difficult to achieve for nervous system tumors. Current response criteria vary depending on the pathology and have several limitations. Until recently, the most widely used criteria for gliomas were "Macdonald criteria," based on two-dimensional tumor measurements on neuroimaging studies. However, the Response Assessment in Neuro-Oncology (RANO) Working Group has published new recommendations in high-grade gliomas and is working on recommendations for other nervous system tumors. This article reviews current response criteria for high-grade glioma, low-grade glioma, brain metastasis, meningioma, and schwannoma.

Erlotinib for progressive vestibular schwannoma in neurofibromatosis 2 patients

OBJECTIVE

In vitro treatment of Nf2-deficient cells with epidermal growth factor receptor (EGFR) inhibitors can reduce cellular proliferation. We sought to determine the activity of erlotinib for progressive vestibular schwannoma (VS) associated with neurofibromatosis 2 (NF2).

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Eleven NF2 patients with progressive VS who were poor candidates for standard therapy.

INTERVENTION

Erlotinib 150 mg daily.

MAIN OUTCOME MEASURES

A radiographic response was defined as >or= 20% decrease in tumor volume compared with baseline. A hearing response was defined as a statistically significant increase in word recognition score (WRS) compared with baseline; a minor hearing response was defined as a 10 dB improvement in pure-tone average with stable WRS.

RESULTS

: Before treatment, the median and mean annual volumetric growth rate for 11 index VS were 26% and 46%, respectively. Among 10 evaluable patients, the median time-to-tumor progression was 9.2 months. Three patients with stable disease experienced maximum tumor shrinkage of 4%, 13%, and 14%. Nine patients underwent audiologic evaluations. One experienced a transient hearing response, 2 experienced minor hearing responses, 3 remained stable, and 2 developed progressive hearing loss. The median time-to-progressive hearing loss was 9.2 months and to either tumor growth or progressive hearing loss was 7.1 months. Adverse treatment effects included mild-to-moderate rash, diarrhea, and hair thinning, with 2 episodes of grade 3 toxicity.

CONCLUSION

Erlotinib treatment was not associated with radiographic or hearing responses in NF2 patients with progressive VS. Because a subset of patients experienced prolonged stable disease, time-to-progression may be more appropriate than radiographic or hearing response for anti-EGFR agents in NF2-associated VS.

A rare retroperitoneal schwannoma in a patient with neurofibromatosis Type 2

Neurofibromatosis Type 2 (NF2) is a dominantly inherited tumour-prone disorder, characterized by the development of multiple schwannomas, meningiomas and ependymomas. Its prevalence is around 1:60 000. Vestibular schwannoma (VS) is the hallmark of NF2. Retroperitoneal schwannomas are expected to occur in only 3% of cases. We present the case of a large retroperitoneal schwannoma in a patient with NF2. A well-circumscribed heterogenic mass (9.5 × 4 × 4 cm) behind and under the left kidney and extending into the left retroperitoneal space was revealed during a lumbar and retroperitoneal space magnetic resonance imaging (MRI). Brain, orbits, cervical, thoracic and lumbar MRI revealed bilateral VS, multiple meningiomas as well as multiple schwannomas and ependymomas in the cervical, thoracic and lumbar spine. The retroperitoneal mass represents a schwannoma probably derived from an intercostal nerve. The patient underwent neurosurgical excision of the VS, and 3 months later, the patient's condition remained stable.

Hearing improvement after bevacizumab in patients with neurofibromatosis type 2

BACKGROUND

Profound hearing loss is a serious complication of neurofibromatosis type 2, a genetic condition associated with bilateral vestibular schwannomas, benign tumors that arise from the eighth cranial nerve. There is no medical treatment for such tumors.

METHODS

We determined the expression pattern of vascular endothelial growth factor (VEGF) and three of its receptors, VEGFR-2, neuropilin-1, and neuropilin-2, in paraffin-embedded samples from 21 vestibular schwannomas associated with neurofibromatosis type 2 and from 22 sporadic schwannomas. Ten consecutive patients with neurofibromatosis type 2 and progressive vestibular schwannomas who were not candidates for standard treatment were treated with bevacizumab, an anti-VEGF monoclonal antibody. An imaging response was defined as a decrease of at least 20% in tumor volume, as compared with baseline. A hearing response was defined as a significant increase in the word-recognition score, as compared with baseline.

RESULTS

VEGF was expressed in 100% of vestibular schwannomas and VEGFR-2 in 32% of tumor vessels on immunohistochemical analysis. Before treatment, the median annual volumetric growth rate for 10 index tumors was 62%. After bevacizumab treatment in the 10 patients, tumors shrank in 9 patients, and 6 patients had an imaging response, which was maintained in 4 patients during 11 to 16 months of follow-up. The median best response to treatment was a volumetric reduction of 26%. Three patients were not eligible for a hearing response; of the remaining seven patients, four had a hearing response, two had stable hearing, and one had progressive hearing loss. There were 21 adverse events of grade 1 or 2.

CONCLUSIONS

VEGF blockade with bevacizumab improved hearing in some, but not all, patients with neurofibromatosis type 2 and was associated with a reduction in the volume of most growing vestibular schwannomas.