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Russell R. Lonser, Debbie K. Song, Jacob Klapper, Marygrace Hagan, Sungyoung Auh, P. Benjamin Kerr, Deborah E. Citrin, John D. Heiss, Kevin Camphausen, and Steven A. Rosenberg

Object

Despite the increasing use of immunotherapy in the treatment of metastatic melanoma, the effects of this therapy on the management of patients with associated brain metastases are not completely defined. The authors undertook this study to determine the effectiveness of resection and the effects of immunotherapy on brain metastasis management.

Methods

The authors analyzed data pertaining to consecutive patients with metastatic melanoma treated with immunotherapy within 3 months of discovery of brain metastases that were surgically resected.

Results

Forty-one patients (median age 44.4 years, range 19.2–63.1 years) underwent resection of 53 brain metastases (median number of metastases 1, range 1–4). The median metastasis volume was 2.5 cm3. Fifteen patients underwent whole-brain radiation therapy (WBRT) and 26 patients did not. Duration of survival from brain metastasis diagnosis was not significantly different between patients who received WBRT (mean 24.9 months) and those who did not (mean 23.3 months) (p > 0.05). Local and distant brain recurrence rates were not statistically different between the WBRT (7.1% and 28.6%, respectively) and non-WBRT (7.7% and 41.0%) groups for the duration of follow-up (p > 0.05). An objective systemic response to immunotherapy was associated with increased duration of survival (p < 0.05).

Conclusions

Resection of melanoma brain metastases in patients treated with immunotherapy provides excellent local control with low morbidity. An objective response to systemic immunotherapy is associated with a prolonged survival in patients who have undergone resection of melanoma brain metastases. Moreover, adjuvant WBRT in melanoma immunotherapy patients with limited metastatic disease to the brain does not appear to provide a significant survival benefit.

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Jie Lu, Zhengping Zhuang, Debbie K. Song, Gautam U. Mehta, Barbara Ikejiri, Harry Mushlin, Deric M. Park, and Russell R. Lonser

Object

Nuclear receptor corepressor (N-CoR) forms a complex that maintains neural stem cells in an undifferentiated state through transcriptional repression. Recently, it has been shown that N-CoR is overexpressed in glioblastoma multiforme (GBM) tumor stem cells and has a putative role in maintaining these cells in an undifferentiated immortal state. To determine the effects of disruption of N-CoR complex function by serine/threonine protein phosphatase 2A (PP2A) inhibition on GBM tumor cell differentiation and proliferation, the authors developed and investigated a competitive small molecule inhibitor (LB1) of PP2A in GBM.

Methods

The authors investigated the effects of LB1 on GBM proliferation and molecular differentiation pathways using in vitro and in vivo studies.

Results

The LB1 inhibited PP2A, leading to increased levels of phosphorylated Akt kinase and decreased NCoR expression, as well as dose-dependent antiproliferative activity in cultured U87 and U251 malignant glioma cells (dose range 1–10 μM). Systemic LB1 treatment (1.5 mg/kg/day for 21 days) had significant tumor antiproliferative effects in mice harboring U87 glioma xenografts (73% mean reduction in tumor volume compared with controls; p < 0.001). Moreover, a reduction in PP2A expression and activity after LB1 treatment in vivo correlated with increased Akt phosphorylation, reduced nuclear N-CoR expression and N-CoR cytoplasmic translocation, and increased accumulation of acetylated core histones, which coincided with the appearance of glial fibrillary acidic protein–expressing tumor cells.

Conclusions

These findings indicate that PP2A inhibition effectively disrupts N-CoR complex function/expression and leads to cytoplasmic translocation of N-CoR with subsequent tumor cell differentiation and/or death. Therapeutic paradigms that target N-CoR function in the cancer stem cell component of malignant gliomas may have treatment utility.

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Debbie K. Song and Russell R. Lonser

Because of the multiplicity and saltatory growth pattern associated with central nervous system hemangioblastomas in von Hippel-Lindau (VHL) disease, resection of individual tumors is usually reserved until symptoms occur, to avoid unnecessary surgery over the lifetime of a patient. Brainstem hemangioblastomas in VHL typically cause lower cranial nerve dysfunction, long-tract signs, sensory impairment, and gait abnormalities. The authors report on a 16-year-old girl with VHL who presented with abnormal early satiety resulting in growth and developmental arrest associated with a growing obex hemangioblastoma. Tumor resection resulted in restoration of appetite, with rapid weight gain, growth in stature, and onset of menses. These findings indicate that caudal brainstem-mediated mechanisms have a profound effect on satiety. Moreover, brainstem hemangioblastomas may present with abnormalities in satiety and feeding that can be effectively reversed with resection.