A phase I dose-escalation study of pulsatile afatinib in patients with recurrent or progressive brain cancer.

Background: Afatinib (BIBW2992; Gilotrif®) is a selective and irreversible inhibitor of the epidermal growth factor receptor (ErbB; EGFR) family. It inhibits EGFR, HER2, and HER4 phosphorylation, resulting in tumor growth inhibition and regression. This phase I dose-escalation trial of pulsatile afatinib examined the safety, drug penetration into the central nervous system, preliminary antitumor activity, and recommended phase II dose in patients with progressive or recurrent brain cancers. Methods: Afatinib was taken orally once every 4 days or once every 7 days depending on dose cohort, until disease progression or unacceptable toxicity. Results: A total of 24 patients received the investigational agent and were evaluable for safety analyses, and 21 patients were evaluable for efficacy. Dosing was administered at 80 mg every 4 days, 120 mg every 4 days, 180 mg every 4 days, or 280 mg every 7 days. A recommended phase II dose of pulsatile afatinib was established at 280 mg every 7 days as there were no dose-limiting toxicities in any of the dosing cohorts and all toxicities were deemed manageable. The most common drug-related toxicities were diarrhea, rash, nausea, vomiting, fatigue, stomatitis, pruritus, and limb edema. Out of the 21 patients evaluable for efficacy, 2 patients (9.5%) exhibited partial response based on Response Assessment in Neuro-Oncology criteria and disease stabilization was seen in 3 patients (14.3%). Conclusions: Afatinib taken orally was safe and well-tolerated up to 280 mg every 7 days in brain cancer patients.

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).

Pilot Study of High-Dose Pemetrexed in Patients with Progressive Chordoma.

PURPOSE: Chordomas are ultrarare tumors of the axial spine and skull-base without approved systemic therapy. Most chordomas have negative expression of thymidylate synthase (TS), suggesting a potential for responding to the antifolate agent pemetrexed, which inhibits TS and other enzymes involved in nucleotide biosynthesis. We evaluated the therapeutic activity and safety of high-dose pemetrexed in progressive chordoma. PATIENTS AND METHODS: Adult patients with previously treated, progressive chordoma participated in an open-label, single-institution, single-arm, pilot clinical trial of intravenous pemetrexed 900 mg/m2 every 3 weeks and supportive medications of folic acid, vitamin B12, and dexamethasone. The primary endpoint was objective response rate according to RECIST v1.1. Secondary endpoints included adverse events, progression-free survival (PFS), tumor molecular profiles, and alterations in tissue and blood-based biomarkers. RESULTS: Fifteen patients were enrolled and the median number of doses administered was 15 (range, 4-31). One patient discontinued treatment due to psychosocial issues after four cycles and one contracted COVID-19 after 13 cycles. Of the 14 response-evaluable patients, 2 (14%) achieved a partial response and 10 (71%) demonstrated stable disease. Median PFS was 10.5 months (95% confidence interval: 9 months-undetermined) and 6-month PFS was 67%. Adverse events were expected and relatively mild, with one grade 3 creatinine increased, and one each of grade 3 and 4 lymphopenia. No grade 5 adverse events, unexpected toxicities, or dose-limiting toxicities were observed. Several patients reported clinical improvement in disease-related symptoms. CONCLUSIONS: High-dose pemetrexed appears tolerable and shows objective antitumor activity in patients with chordoma. Phase II studies of high-dose pemetrexed are warranted.

BETA prime: a first-in-man phase 1 study of AdAPT-001, an armed oncolytic adenovirus for solid tumors.

AdAPT-001 is an oncolytic adenovirus (OAV) with a transforming growth factor beta (TGF-ß) trap, which neutralizes the immunosuppressive and profibrotic cytokine, TGF-ß. The aim or purpose of this phase 1 study was to assess the safety and tolerability and, secondarily, the efficacy of AdAPT-001 after single intratumoral injection (IT) (Part 1) and multidose IT injection (Part 2) in patients with superficially accessible, advanced refractory solid tumors. Part 1 enrolled 9 patients with a 3 + 3 single dose-escalation safety run-in involving 2.5 × 1011, 5.0 × 1011, 1.0 × 1012 viral particles (vps). No dose-limiting toxicities or treatment-related serious adverse events (SAEs) were seen. In Part 2, a dose-expansion phase, 19 patients received AdAPT-001 at 1.0 × 1012 vps until disease progression according to Response Evaluation Criteria in Solid Tumors or RECIST 1.1. The overall responses to treatment included confirmed partial responses (3), durable stable disease ≥ 6 months (5), and progressive disease (13). AdAPT-001 is well tolerated. Evidence of an anti-tumor effect was seen in both injected and uninjected lesions. The recommended Phase 2 dose was 1.0 × 1012 vp administered by intratumoral injection once every 2 weeks. Combination of AdAPT-001 with a checkpoint inhibition is enrolling.

Response to OKN-007 and NAC in a Patient with Unilateral Hearing Loss and Chronic Tinnitus from Vestibular Schwannoma.

BACKGROUND: Tinnitus is the perception of sound in the absence of external acoustic stimulation. Being one of the most common diseases of the ear, it has a global prevalence ranging from 4.1 to 37.2%. To date, it has been difficult to treat tinnitus as its pathophysiology is poorly understood and there are limited treatment options. OBJECTIVE: To investigate the effect of OKN-007 (also known as HPN-07), a nitrone-based investigational drug, in combination with oral N-acetylcycsteine (NAC), for the treatment of hearing loss and chronic tinnitus under an individual expanded access protocol. PATIENT CASE: We report the case of a patient who presented with left-sided ear fullness, mild tinnitus, and mild high frequency sensorineural hearing loss with 100% word recognition. A large enhancing mass seen on MRI revealed a vestibular schwannoma. He underwent subtotal resection of the tumor resulting in a moderate-to-profound sensorineural hearing loss and catastrophic tinnitus. The patient was treated with intravenous OKN-007 at 60 mg/kg dosed three times per week and oral NAC 2500 mg twice daily. RESULTS: Post-treatment audiometric testing revealed an average of 16.66 dB in hearing threshold improvement in three frequencies (125, 250 and 500 Hz) with residual hearing in the affected left ear. His tinnitus loudness matching improved from 90 dB to 19 dB post-treatment. His Tinnitus Handicap Inventory improved from 86/100 (Catastrophic) to 40/100 (Moderate). He also experienced improvements in sleep, concentration, hearing, and emotional well-being, and reported significantly decreased levels of tinnitusrelated distress. CONCLUSIONS: This case report highlights the feasibility and therapeutic potential of the combination of OKN-007 and NAC in treating hearing loss and tinnitus that warrants further investigation.

Detection of perillyl alcohol and its metabolite perillic acid in postsurgical glioblastoma tissue after intranasal administration of NEO100: illustrative case.

BACKGROUND: Intranasal delivery of NEO100, a pharmaceutical-grade version of the natural monoterpene perillyl alcohol (POH), is undergoing clinical phase IIa testing as a treatment for glioblastoma (GBM). However, so far there is no evidence that intranasal delivery of NEO100 indeed results in POH reaching intracranial malignancies in a patient. OBSERVATIONS: After surgical removal of her recurrent GBM tumor, a patient received daily intranasal NEO100 therapy for more than 3 years before a second recurrence emerged. At that time, a final dose of NEO100 was given shortly before the tumor tissue was surgically removed, and the tissue was processed for high-performance liquid chromatography analysis of POH and its primary metabolite, perillic acid (PA). Both molecules could readily be detected in the tumor tissue. LESSONS: This is the first demonstration of POH and PA in brain tumor tissue from any patient. It reveals that intranasal administration of NEO100 is a valid approach to achieve delivery of this agent to a brain tumor. In view of the noninvasive and safe nature of this method, along with tentative indications of activity, our findings add confidence to the notion that intranasal administration of NEO100 holds potential as a new treatment option for brain-localized malignancies.

Circulating Tumor Cell Transcriptomics as Biopsy Surrogates in Metastatic Breast Cancer.

BACKGROUND: Metastatic breast cancer (MBC) and the circulating tumor cells (CTCs) leading to macrometastases are inherently different than primary breast cancer. We evaluated whether whole transcriptome RNA-Seq of CTCs isolated via an epitope-independent approach may serve as a surrogate for biopsies of macrometastases. METHODS: We performed RNA-Seq on fresh metastatic tumor biopsies, CTCs, and peripheral blood (PB) from 19 newly diagnosed MBC patients. CTCs were harvested using the ANGLE Parsortix microfluidics system to isolate cells based on size and deformability, independent of a priori knowledge of cell surface marker expression. RESULTS: Gene expression separated CTCs, metastatic biopsies, and PB into distinct groups despite heterogeneity between patients and sample types. CTCs showed higher expression of immune oncology targets compared with corresponding metastases and PB. Predictive biomarker (n = 64) expression was highly concordant for CTCs and metastases. Repeat observation data post-treatment demonstrated changes in the activation of different biological pathways. Somatic single nucleotide variant analysis showed increasing mutational complexity over time. CONCLUSION: We demonstrate that RNA-Seq of CTCs could serve as a surrogate biomarker for breast cancer macrometastasis and yield clinically relevant insights into disease biology and clinically actionable targets.

Molecularly targeted treatment of recurrent anaplastic astrocytoma - a case report.

High-grade astrocytomas are malignant and aggressive, with limited treatment options. Treatment is geared not only toward increasing patient's overall survival but also in delaying or preventing neurological disability, a cause of significant morbidity. Increasingly, targeted and customized treatment approaches, especially for recurrent disease, are being explored. Here we present a successful outcome in a young patient with rapidly progressive disease who responded to targeted treatment based on genetic sequencing and circulating tumor DNA markers, given the inaccessibility of the tissue to biopsy. Molecular testing on tissue, serum or CSF may be helpful in identifying unique targets in these complex patients.

Phase I trial of intranasal NEO100, highly purified perillyl alcohol, in adult patients with recurrent glioblastoma.

BACKGROUND: Better treatments for glioblastoma (GBM) patients, in particular in the recurrent setting, are urgently needed. Clinical trials performed in Brazil indicated that intranasal delivery of perillyl alcohol (POH) might be effective in this patient group. NEO100, a highly purified version of POH, was current good manufacturing practice (cGMP) manufactured to evaluate the safety and efficacy of this novel approach in a Phase I/IIa clinical trial in the United States. METHODS: A total of 12 patients with recurrent GBM were enrolled into Phase I of this trial. NEO100 was administered by intranasal delivery using a nebulizer and nasal mask. Dosing was 4 times a day, every day. Four cohorts of 3 patients received the following dosages: 96 mg/dose (384 mg/day), 144 mg/dose (576 mg/day), 192 mg/dose (768 mg/day), and 288 mg/dose (1152 mg/day). Completion of 28 days of treatment was recorded as 1 cycle. Adverse events were documented, and radiographic response via Response Assessment in Neuro-Oncology (RANO) criteria was evaluated every 2 months. Progression-free and overall survival were determined after 6 and 12 months, respectively (progression-free survival-6 [PFS-6], overall survival-12 [OS-12]). RESULTS: Intranasal NEO100 was well tolerated at all dose levels and no severe adverse events were reported. PFS-6 was 33%, OS-12 was 55%, and median OS was 15 months. Four patients (33%), all of them with isocitrate dehydrogenase 1 (IDH1)-mutant tumors, survived >24 months. CONCLUSION: Intranasal glioma therapy with NEO100 was well tolerated. It correlated with improved survival when compared to historical controls, pointing to the possibility that this novel intranasal approach could become useful for the treatment of recurrent GBM.

Characterization of molecular pathways for targeting therapy in glioblastoma.

Glioblastoma remains the most common malignant brain neoplasm in adults. The available therapies for treatment have only modestly extended survival. Traditional chemotherapy agents have shown only slight effectiveness in controlling this disease. The use of molecular profiling has allowed personalized medicine options to be explored for the care of these individuals. Targeted therapies have shown significant benefit in numerous other cancer types with survival being extended significantly. In glioblastoma, several promising markers have been identified including vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), and programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1). These targets have been shown to play a critical role in glioblastoma formation and proliferation. The pathways of these receptors have been elucidated in detail. This level of understanding has led to the a more robust understanding of possible mechanism of pathway modification. The targeting of these specific markers has led to the development of several selective therapies with additional therapies being evaluated. The clinical trials validating these markers have been promising but have yet to show a clear benefit in brain tumors. This identification of alternative methods to address these markers or identify additional targets may be the key to the fight against this disease. The molecular targeting of glioblastoma pathways may have significant impact on disease control and patient survival.

NRG/RTOG 1122: A phase 2, double-blinded, placebo-controlled study of bevacizumab with and without trebananib in patients with recurrent glioblastoma or gliosarcoma.

BACKGROUND: Targeting vascular endothelial growth factor (VEGF) alone does not improve overall survival (OS) in recurrent glioblastoma (rGBM). The angiopoiein (Ang)-TIE2 system may play a role in tumor survival under VEGF inhibition. We conducted a phase 2, double-blinded, placebo-controlled trial of bevacizumab plus trebananib (a novel Fc fusion protein that sequesters Ang1/Ang2) over bevacizumab alone in rGBM. METHODS: Patients ≥18 years of age with a Karnofsky performance status ≥70 and GBM or variants in first or second relapse were randomized to bevacizumab 10 mg/kg every 2 weeks plus trebananib 15 mg/kg every week or bevacizumab plus placebo. The primary endpoint was 6-month progression-free survival (PFS). RESULTS: After an initial 6-patient lead-in cohort confirmed the safety of combining bevacizumab and trebananib, 115 eligible patients were randomized to the control (n = 58) or experimental treatment (n = 57). In the control arm, 6-month PFS was 41.1%, median survival time was 11.5 months (95% CI, 8.4-14.2 months), median PFS was 4.8 months (95% CI, 3.8-7.1 months), and radiographic response (RR) was 5.9%. In the experimental arm, 6-month PFS was 22.6%, median survival time was 7.5 months (95% CI, 6.8-10.1 months), median PFS was 4.2 months (95% CI, 3.7-5.6 months), and RR was 4.2%. The rate of severe toxicities was not significantly different between arms. CONCLUSION: The combination of bevacizumab and trebananib was well tolerated but did not significantly improve 6-month PFS rate, PFS, or OS for patients with rGBM over bevacizumab alone. The shorter PFS in the experimental arm with a hazard ratio of 1.51 (P = .04) suggests that the addition of trebananib to bevacizumab is detrimental.

Identifying Disparities in Care in Treating Glioblastoma: A Retrospective Cohort Study of Patients Treated at a Safety-net Versus Private Hospital Setting.

BACKGROUND: Patients of lower socioeconomic status (SES) may experience barriers to their oncologic care, but current data conflict over whether SES affects the prognosis of patients with glioblastoma (GB). OBJECTIVE: We sought to determine whether SES disparities impaired delivery of neuro-oncologic care and affected the prognosis of GB patients. METHODS: The records of GB patients treated from 2010 to 2014 at a safety-net hospital (SNH) or private hospital (PH), both served by 1 academic medical institution, were retrospectively reviewed and compared. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. RESULTS: A total of 55 SNH and 39 PH GB patients were analyzed with median 11-month follow-up. SNH patients were predominantly Hispanic, low income, enrolled in Medicaid, were less likely to receive radiation (89% vs. 100%), took longer to start radiation (41 vs. 29 days), and were less likely to complete radiation treatment (80% vs. 95%). Concurrent and adjuvant temozolomide use were also lower (85% vs. 94% and 60% vs. 71%, respectively). OS and PFS were not significantly different (15 vs. 16 months and 8 vs. 11 months, respectively). On multivariate analysis, adjuvant chemotherapy and RT completion predicted for better OS, whereas hospital type, income, and insurance did not. CONCLUSION: Although GB patients at our SNH received less adjuvant treatment compared with PH, outcomes were similar. Access to multidisciplinary care staffed by academic physicians may play an important role in overcoming socioeconomic barriers to treatment availability and quality at SNHs.

Stereotactic radiosurgery and ipilimumab for patients with melanoma brain metastases: clinical outcomes and toxicity.

INTRODUCTION: There is evidence that the combination of ipilimumab and stereotactic radiosurgery (SRS) for brain metastases improves outcomes. We investigated clinical outcomes, radiation toxicity, and impact of ipilimumab timing in patients treated with SRS for melanoma brain metastases. METHODS: We retrospectively identified 91 patients treated with SRS at our institution for melanoma brain metastases from 2006 to 2015. Concurrent ipilimumab administration was defined as within ± 4 weeks of SRS procedure. Acute and late toxicities were graded with CTCAE v4.03. Overall survival (OS), local failure, distant brain failure, and failure-free survival were analyzed with the Kaplan-Meier method. OS was analyzed with Cox regression. RESULTS: Twenty-three patients received ipilimumab concurrent with SRS, 28 patients non-concurrently, and 40 patients did not receive ipilimumab. The median age was 62 years and 91% had KPS ≥ 80. The median follow-up time was 7.4 months. Patients who received ipilimumab had a median OS of 15.1 months compared to 7.8 months in patients who did not (p = 0.02). In multivariate analysis, ipilimumab (p = 0.02) and diagnosis-specific graded prognostic assessment (p = 0.02) were associated with OS. There were no differences in intracranial control by ipilimumab administration or timing. The incidence of radiation necrosis was 5%, with most events occurring in patients who received ipilimumab. CONCLUSIONS: Patients who received ipilimumab had improved OS even after adjusting for prognostic factors. Ipilimumab did not appear to increase risk for acute toxicity. The majority of radiation necrosis events, however, occurred in patients who received ipilimumab. Our results support the continued use of SRS and ipilimumab as clinically appropriate.

Combination ipilimumab and radiosurgery for brain metastases: tumor, edema, and adverse radiation effects.

OBJECTIVETumor and edema volume changes of brain metastases after stereotactic radiosurgery (SRS) and ipilimumab are not well described, and there is concern regarding the safety of combination treatment. The authors evaluated tumor, edema, and adverse radiation-induced changes after SRS with and without ipilimumab and identified associated risk factors.METHODSThis single-institution retrospective study included 72 patients with melanoma brain metastases treated consecutively with upfront SRS from 2006 to 2015. Concurrent ipilimumab was defined as ipilimumab treatment within 4 weeks of SRS. At baseline and during each follow-up, tumor and edema were measured in 3 orthogonal planes. The (length × width × height/2) formula was used to estimate tumor and edema volumes and was validated in the present study for estimation of edema volume. Tumor and edema volume changes from baseline were compared using the Kruskal-Wallis test. Local failure, lesion hemorrhage, and treatment-related imaging changes (TRICs) were analyzed with the Cox proportional hazards model.RESULTSOf 310 analyzed lesions, 91 were not treated with ipilimumab, 59 were treated with concurrent ipilimumab, and 160 were treated with nonconcurrent ipilimumab. Of 106 randomly selected lesions with measurable peritumoral edema, the mean edema volume by manual contouring was 7.45 cm3 and the mean volume by (length × width × height)/2 formula estimation was 7.79 cm3 with R2 = 0.99 and slope of 1.08 on line of best fit. At 6 months after SRS, the ipilimumab groups had greater tumor (p = 0.001) and edema (p = 0.005) volume reduction than the control group. The concurrent ipilimumab group had the highest rate of lesion response and lowest rate of lesion progression (p = 0.002). Within the concurrent ipilimumab group, SRS dose ≥ 20 Gy was associated with significantly greater median tumor volume reduction at 3 months (p = 0.01) and 6 months (p = 0.02). The concurrent ipilimumab group also had the highest rate of lesion hemorrhage (p = 0.01). Any ipilimumab was associated with higher incidence of symptomatic TRICs (p = 0.005). The overall incidence of pathologically confirmed radiation necrosis (RN) was 2%. In multivariate analysis, tumor and edema response at 3 months were the strongest predictors of local failure (HR 0.131 and HR 0.125) and lesion hemorrhage (HR 0.225 and HR 0.262). Tumor and edema response at 1.5 months were the strongest predictors of TRICs (HR 0.144 and HR 0.297).CONCLUSIONSThe addition of ipilimumab improved tumor and edema volume reduction but was associated with a higher incidence of lesion hemorrhage and symptomatic TRICs. There may be a radiation dose-response relationship between SRS and ipilimumab when administered concurrently. Early tumor and edema response were excellent predictors of subsequent local failure, lesion hemorrhage, and TRICs. The incidence of pathologically proven RN was low, supporting the relative safety of ipilimumab in radiosurgery treatment.

Malignant transformation of DNETs: a case report and literature review.

Dysembryoplastic neuroepithelial tumors (DNETs) have traditionally been thought of as lesions with a benign clinical course that generally do not undergo malignant transformation. However, cases are emerging of DNETs that progress to more malignant forms. We present a case of malignant transformation, and we compile and review all previously published cases to identify common characteristics that may confer a higher risk for malignant transformation. A PubMed search was performed of all English-language case reports of DNET transformations to malignant cancers. The demographic, clinical, and histologic features of these patients are compiled and analyzed. A separate case report with histologic descriptions is also presented. A total of 10 case reports of DNET malignant transformation were found. The majority of cases involved complex-type DNETs. A higher proportion of extratemporal lesions were observed. Almost all cases involved subtotal resection. Risk factors for malignant progression of DNET lesions include complex-type histologic features, extratemporal location, and subtotal resection. Malignant dedifferentiation of astrocytic or oligodendrocytic cells within the glial nodule of complex DNETs may be the source of these transformations. There are no radiographic features that differentiate DNETs that are at higher risk for transformation.

Diffusion restriction in a non-enhancing metastatic brain tumor treated with bevacizumab - recurrent tumor or atypical necrosis?

A 38-year-old female with metastatic brain cancer developed non-enhancing, diffusion restricted lesions following bevacizumab treatment. From our review of the literature, this is the first reported case of this type of lesion. Clinicians should be wary of these lesions, as they can represent either tumor progression or necrosis/effects of chronic hypoxia from anti-angiogenic therapy. Further investigation is necessary to determine the biological mechanism and clinical significance of this type of imaging appearance.

Recent developments in chemotherapy for meningiomas: a review.

OBJECT: Currently, few medical options exist for refractory and atypical/anaplastic meningiomas. New developments in chemotherapeutic options for meningiomas have been explored over the past decade. The authors review these recent developments, with an emphasis on emerging avenues for therapy, clinical efficacy, and adverse effects. METHODS: A review of the literature was performed to identify any studies exploring recent medical and chemotherapeutic agents that have been or are currently being tested for meningiomas. RESULTS: from included preclinical and human clinical trials were reviewed and summarized. RESULTS: Current guidelines recommend only 3 drugs that can be used to treat patients with refractory and highgrade meningiomas: hydroxyurea, interferon-α 2B, and Sandostatin long-acting release. Recent developments in the medical treatment of meningiomas have been made across a variety of pharmacological classes, including cytotoxic agents, hormonal agents, immunomodulators, and targeted agents toward a variety of growth factors and their signaling cascades. Promising avenues of therapy that are being evaluated for efficacy and safety include antagonists of platelet-derived growth factor receptor, epidermal growth factor receptor, vascular endothelial growth factor receptor, and mammalian target of rapamycin. Because malignant transformation in meningiomas is likely to be mediated by numerous processes interacting via a complex matrix of signals, combination therapies affecting multiple molecular targets are currently being explored and hold significant promise as adjuvant therapy options. CONCLUSIONS: Improved understanding of the molecular mechanisms driving meningioma tumorigenesis and malignant transformation has resulted in the targeted development of more specific agents for chemotherapeutic intervention in patients with nonresectable, aggressive, and malignant meningiomas.