Neuroinflammatory changes of the normal brain tissue in cured mice following combined radiation and anti-PD-1 blockade therapy for glioma.

The efficacy of combining radiation therapy with immune checkpoint inhibitor blockade to treat brain tumors is currently the subject of multiple investigations and holds significant therapeutic promise. However, the long-term effects of this combination therapy on the normal brain tissue are unknown. Here, we examined mice that were intracranially implanted with murine glioma cell line and became long-term survivors after treatment with a combination of 10 Gy cranial irradiation (RT) and anti-PD-1 checkpoint blockade (aPD-1). Post-mortem analysis of the cerebral hemisphere contralateral to tumor implantation showed complete abolishment of hippocampal neurogenesis, but neural stem cells were well preserved in subventricular zone. In addition, we observed a drastic reduction in the number of mature oligodendrocytes in the subcortical white matter. Importantly, this observation was evident specifically in the combined (RT + aPD-1) treatment group but not in the single treatment arm of either RT alone or aPD-1 alone. Elimination of microglia with a small molecule inhibitor of colony stimulated factor-1 receptor (PLX5622) prevented the loss of mature oligodendrocytes. These results identify for the first time a unique pattern of normal tissue changes in the brain secondary to combination treatment with radiotherapy and immunotherapy. The results also suggest a role for microglia as key mediators of the adverse treatment effect.

Repolarized macrophages, induced by intermediate stereotactic dose radiotherapy and immune checkpoint blockade, contribute to long-term survival in glioma-bearing mice.

INTRODUCTION: Glioblastoma multiforme (GBM) is a deadly brain tumor with a short expected median survival, despite current standard-of-care treatment. We explored the combination of intermediate stereotactic dose radiation therapy and immune checkpoint inhibitor therapy as a novel treatment strategy for GBM. METHODS: Glioma xenograft-bearing mice were exposed to high dose brain-directed radiation (10 Gy single exposure) as well as mouse anti-PD-1 antibody. The tumor-bearing animals were randomized to four groups: no treatment, radiation alone, anti-PD-1 alone, and radiation + anti-PD-1. Survival was followed, and tumor growth was monitored using MRI. Immunohistochemistry, gene expression arrays, and flow cytometry were used to characterize the treatment-induced effects. Pharmacologic inhibitors of T-lymphocytes, bone marrow derived macrophages, and microglia were used to assess the respective roles of different immune populations in observed treatment effects. RESULTS: We found the combined treatment with high dose radiation and immunotherapy to be highly effective with a 75% complete pathologic response and dramatically improved survival outcomes. We found both CD8+ T-cells and macrophages to be necessary for the full effect of combined therapy, with T lymphocytes appearing to play a role early on and macrophages mediating a later phase of the combined treatment effect. Radiation treatment appeared to trigger macrophage repolarization, increasing M1/M2 ratio. CONCLUSIONS: These findings point to a novel immunologic mechanism underlying the interaction between radiotherapy and immunotherapy. They also provide the basis for clinical investigation of immunogenic dose radiation in combination with immune checkpoint blockade as a potential treatment approach for newly diagnosed high grade gliomas.

Mitigation of radiation myelopathy and reduction of microglial infiltration by Ramipril, ACE inhibitor.

STUDY DESIGN: Experimental study. OBJECTIVES: To evaluate the efficacy of Angiotensin-converting enzyme inhibitor Ramipril, as a mitigator of radiation-induced spinal cord injury. SETTING: Stony Brook University, Stony Brook, NY, USA. METHODS: Total of 22 rats were irradiated with single doses of 23.6-33 Gy at the C4-T2 spinal levels. After irradiation, the rats were randomized to the radiation only control group and the Ramipril-treated (radiation + Ramipril) experimental group. Ramipril 1.5 mg/kg/day was given in the drinking water starting 1 week after radiation through the study duration. RESULTS: All the rats irradiated with 28.5-33 Gy became paralyzed at 125 ± 4 days, whereas no rats became paralyzed after 23.6 Gy. The time to develop paralysis was delayed to 135 ± 4 days in Ramipril-treated group (P < 0.001). H&E and LFB showed microscopic structural restoration and remyelination with Ramipril treatment. VEGF expression was increased in the irradiated spinal cord, and the number of VEGF-positive cells was significantly decreased by Ramipril treatment (P < 0.001). Immunohistochemical stain with Iba-1 showed increased microglial infiltration in the irradiated spinal cords. The number of Iba-1-positive microglia was significantly reduced by Ramipril treatment (P < 0.05). CONCLUSION: Ramipril reduced the rate of paralysis even at the paralysis-inducing radiation doses. It also significantly delayed the onset of paralysis. Neuroinflammation and endothelial cell damage may be the key mediators of radiation injury. Ramipril can be readily translatable to clinical application as a mitigatory of radiotherapeutic toxicity.

FTY720/fingolimod, an oral S1PR modulator, mitigates radiation induced cognitive deficits.

PURPOSE: This study evaluates FTY720/Fingolimod, modulator of sphingosine-1-phosphate (S1P) receptor, as a potential mitigator of radiation-induced neurocognitive dysfunction. METHODS AND MATERIALS: To study radiation-induced neurocognitive deficits, 6 week-old C57/Bl/6J mice received 0 or 7Gy cranial irradiation and were treated with FTY720 or vehicle for seven weeks. Fear conditioning and Morris water maze were then employed to test learning and memory. Immunohistochemical staining for neural progenitor cells (NPCs) and mature neurons was used to assess changes in hippocampal neurogenesis. To test effects on tumor growth, mice harboring brain tumor xenografts were treated with FTY720 or vehicle for six weeks. RESULTS: In irradiated mice, learning deficits were manifested by significantly longer latency times in the Morris Water Maze compared to non-irradiated controls (p=0.001). The deficits were fully restored by FTY720. In irradiated brains, FTY720 maintained the cytoarchitecture of the dentate gyrus granular cell layer and partially restored the pool of NPC. In mice harboring brain tumor stem cell (BTSC) xenografts FTY720 delayed tumor growth and improved survival (p=0.012). CONCLUSIONS: FTY720 mitigates radiation-induced learning dysfunction. A partial restoration of neurogenesis was observed. Furthermore, FTY720 appears to delay tumor growth and improve survival in a xenograft glioma mouse model.

Neoadjuvant vs. adjuvant treatment of Siewert type II gastroesophageal junction cancer: an analysis of data from the surveillance, epidemiology, and end results (SEER) registry.

BACKGROUND: Cancer of the gastroesophageal junction (GEJ) has been rising in incidence in recent years. The role of radiation therapy (RT) in the treatment of GEJ cancer remains unclear, as the largest prospective trials advocating for either adjuvant or neoadjuvant chemoradiotherapy (CRT) combine GEJ cancer with either gastric or esophageal cancer. The aim of the present study is to examine the association of neoadjuvant versus adjuvant treatment with overall and disease-specific survival (DSS) for patients with surgically resected cancer of the true GEJ (Siewert type II). METHODS: The surveillance, epidemiology, and end results (SEER) registry database (2001-2011) was queried for cases of surgically resected Siewert type II GEJ cancer. A total of 1,497 patients with resectable GEJ cancer were identified, with 746 receiving adjuvant RT and 751 receiving neoadjuvant RT. Retrospective analysis was performed with the endpoints of overall and DSS. RESULTS: Using cox regression and controlling for independent covariates (age, sex, race, stage, grade, histology, and year of diagnosis), we showed that adjuvant RT was associated with a significantly lower death risk [hazard ratio (HR), 0.84; 95% confidence interval 0.73-0.97; P value=0.0168] and significantly lower disease-specific death risk (HR, 0.84; 95% confidence interval, 0.72-0.97; P value=0.0211) as compared to neoadjuvant RT. CONCLUSIONS: This analysis of SEER data showed that adjuvant RT was associated with a survival benefit as compared to neoadjuvant RT for the treatment of Siewert type II GEJ cancer. We suggest future prospective studies to compare outcomes of adjuvant versus neoadjuvant treatment for true GEJ cancer.

Conformal external beam radiation or selective internal radiation therapy-a comparison of treatment outcomes for hepatocellular carcinoma.

BACKGROUND: Non-operative treatment for hepatocellular carcinoma (HCC) has expanded significantly with the use of selective internal radiotherapy (SIRT) mostly with yttrium 90 ((90)Y) tagged microspheres and highly conformal external beam radiation therapy such as stereotactic body radiotherapy (SBRT) to treat unresectable liver tumors for local tumor control. SBRT is a noninvasive procedure using external radiation source under image guidance, while SIRT delivers radioactive particles by transarterial radioembolization (TARE). However, the survival benefits of SBRT versus SIRT have never been compared. The aim of the present study is to compare the outcomes of overall and disease specific survival (DSS) using SIRT versus SBRT to treat HCC. METHODS: The Surveillance, Epidemiology, and End Results (SEER) registry database [2004-2011] was queried for cases of unresectable HCC. Patients with missing data and those who received surgery were excluded from the study. A total of 189 patients with unresectable HCC were identified and used for statistical analysis, with 112 receiving SBRT and 77 receiving SIRT. Overall and disease-specific survival was compared using multivariable cox proportional hazard models. RESULTS: After adjusting for confounding factors (age at diagnosis, gender, race, grade, stage, AFP level and type of surgery), there were no significant difference in overall survival (OS) [hazard ratio (HR), 0.72; 95% confidence interval (CI), 0.49-1.07; P=0.1077] and DSS (HR, 0.70; 95% CI, 0.46-1.05; P=0.0880) for SIRT compared to SBRT. However, patients with elevated AFP level were associated with higher death risk (P=0.0459) and disease specific death risk (P=0.0233) than those with AFP within normal limits in both treatment groups. CONCLUSIONS: The retrospective analysis serves as the first comparison of SIRT to SBRT in treatment of unresectable HCC. Our findings suggest both treatment approaches result in similar outcomes in overall and disease-specific survival benefit. Future prospective randomized trials are needed to better evaluate and compare the two radiation modalities, as well as other non-operative therapies used in the treatment of HCC.

Myoepithelial Carcinoma: The Role of Radiation Therapy. A Case Report and Analysis of Data From the Surveillance, Epidemiology, and End Results (SEER) Registry.

PURPOSE/OBJECTIVE: The role of radiation therapy in the treatment of myoepithelial carcinoma (MC) is unknown. We present a case of a high-grade soft-tissue MC in a pediatric patient and retrospectively examine the effect of postoperative radiation on survival in patients with MC. MATERIALS AND METHODS: Our patient was treated with 4 cycles of ifosfamide, cisplatin, and etoposide followed by 3 cycles of ifosfamide vincristine and etoposide. Radiation was delivered to a total dose of 5580 cGy in 180 cGy/fraction to the surgical bed with a 2 cm margin starting after the third cycle of chemotherapy. The Surveillance, Epidemiology, and End Results (SEER) registry database was queried for cases of surgically resected MC. Retrospective analysis was performed with the endpoint of overall survival (OS). RESULTS: Two hundred thirty-four cases of MC were identified; for 62 of these cases, the grade of the tumor wasidentified. Of these 62 patients, 27 received postoperative radiation. OS was improved with adjuvant radiation therapy in patients with grade III or IV MC (P<0.01) as determined by the log-rank test. CONCLUSIONS: This analysis of SEER data showed an OS benefit with adjuvant radiation therapy in the treatment of high-grade MC. Physicians should report all cases of MC to improve clinical decision making in the treatment of this rare disease.

Does adjuvant radiotherapy benefit patients with diffuse-type gastric cancer? Results from the Surveillance, Epidemiology, and End Results database.

BACKGROUND: Diffuse-type gastric cancer is observed in approximately one-third of gastric cancers, yet the optimal treatment remains controversial. In the recently published Intergroup 0116 trial, a subgroup analysis demonstrated a lack of a long-term survival benefit for adjuvant chemoradiation therapy among patients with diffuse-type gastric cancer. METHODS: The Surveillance, Epidemiology, and End Results registry database was queried for patients who were newly diagnosed with diffuse-type gastric cancer between 2002 and 2005 and underwent surgical resection with or without adjuvant radiotherapy (RT). Overall survival (OS) was analyzed by the Kaplan-Meier method. Cox proportional hazards models were used to investigate the association between adjuvant RT and OS, with and without adjusting for other factors. In addition, propensity score methods were used to control for the possible effects of measured confounders. RESULTS: A total of 1889 cases of surgically resected diffuse-type gastric cancer were included in the analysis; of these cases, 782 patients received adjuvant RT and 1107 did not receive RT. The median survival time was 30 months in the group treated with adjuvant RT versus 18 months in the group that did not receive RT with matched propensity scores (P<.001). The Cox model confirmed the improvement in OS in patients who received adjuvant RT (hazard ratio, 0.75; 95% confidence interval, 0.65-0.82 [P<.001]). CONCLUSIONS: The current population-based observational study suggested a potential survival benefit for adjuvant RT among patients with diffuse-type gastric cancer. The standard treatment will likely remain controversial until evidence becomes available from phase 3 randomized trials exclusively for patients with diffuse-type gastric cancer.

Soluble adenylyl cyclase is necessary and sufficient to overcome the block of axonal growth by myelin-associated factors.

Neurons in the CNS do not regenerate following injury; regeneration is blocked by inhibitory proteins in myelin, such as myelin-associated glycoprotein (MAG). Elevating neuronal levels of the second messenger cAMP overcomes this blocked axonal outgrowth. One way to elevate cAMP is pretreating neurons with neurotrophins, such as brain-derived neurotrophic factor (BDNF). However, pleiotropic effects and poor bioavailability make exogenous administration of neurotrophins in vivo problematic; therefore, alternative targets must be considered. In neurons, two families of adenylyl cyclases synthesize cAMP, transmembrane adenylyl cyclases (tmACs), and soluble adenylyl cyclase (sAC). Here, we demonstrate that sAC is the essential source of cAMP for BDNF to overcome MAG-dependent inhibition of neurite outgrowth. Elevating sAC in rat and mouse neurons is sufficient to induce neurite outgrowth on myelin in vitro and promotes regeneration in vivo. These results suggest that stimulators of sAC might represent a novel therapeutic strategy to promote axonal growth and regeneration.

The role of postoperative radiation therapy in the treatment of meningeal hemangiopericytoma-experience from the SEER database.

PURPOSE: The aim of this study was to examine the effect of postoperative radiation therapy (RT) on cause-specific survival in patients with meningeal hemangiopericytomas. METHODS AND MATERIALS: The Surveillance, Epidemiology, and End Results database from 1990-2008 was queried for cases of surgically resected central nervous system hemangiopericytoma. Patient demographics, tumor location, and extent of resection were included in the analysis as covariates. The Kaplan-Meier product-limit method was used to analyze cause-specific survival. A Cox proportional hazards regression analysis was conducted to determine which factors were associated with cause-specific survival. RESULTS: The mean follow-up time is 7.9 years (95 months). There were 76 patients included in the analysis, of these, 38 (50%) underwent gross total resection (GTR), whereas the other half underwent subtotal resection (STR). Postoperative RT was administered to 42% (16/38) of the patients in the GTR group and 50% (19/38) in the STR group. The 1-year, 10-year, and 20-year cause-specific survival rates were 99%, 75%, and 43%, respectively. On multivariate analysis, postoperative RT was associated with significantly better survival (HR = 0.269, 95% CI 0.084-0.862; P=.027), in particular for patients who underwent STR (HR = 0.088, 95% CI: 0.015-0.528; P<.008). CONCLUSIONS: In the absence of large prospective trials, the current clinical decision-making of hemangiopericytoma is mostly based on retrospective data. We recommend that postoperative RT be considered after subtotal resection for patients who could tolerate it. Based on the current literature, the practical approach is to deliver limited field RT to doses of 50-60 Gy while respecting the normal tissue tolerance. Further investigations are clearly needed to determine the optimal therapeutic strategy.

Does adjuvant external-beam radiotherapy improve outcomes for nonbenign meningiomas? A Surveillance, Epidemiology, and End Results (SEER)-based analysis.

OBJECT: The aim of this study was to examine the effect of postoperative external-beam radiation therapy (EBRT) on disease-specific survival in patients with nonbenign meningiomas. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database from 1988 to 2007 was queried for cases of resected Grades II (atypical) and III (malignant) meningioma. Disease-specific survival outcomes were determined using Kaplan-Meier survival analysis and Cox proportional hazards models. Logistic regression analysis was used to determine the likelihood of receiving EBRT for Grade II versus Grade III. Because atypical and malignant meningiomas underwent WHO reclassification in 2000, the authors carried out an additional analysis of outcomes of these tumors from 2000 to 2008. RESULTS: There were 657 patients included in the analysis; of these, 244 received adjuvant radiation. Compared with patients with Grade II meningioma, patients with Grade III disease were 41.9% more likely to receive EBRT after gross-total resection and 36.7% more likely to receive it after subtotal resection (95% CI 0.58-3.26). Controlling for grade, extent of resection, size and anatomical location of the tumor, year of diagnosis, race, age, and sex, adjuvant EBRT did not impart a survival benefit (HR 1.492; 95% CI 0.827-2.692). There was also no survival advantage to EBRT in an analysis of cases diagnosed after the WHO 2000 reclassification of meningiomas (HR 0.828; 95% CI 0.350-1.961). CONCLUSIONS: The results of this population-based retrospective analysis demonstrate that the role of radiation remains unclear. They underscore the need for randomized prospective clinical trials to assess the usefulness of adjuvant EBRT in Grades II and III meningioma so as to define more precisely the subset of patients who may benefit from the addition of adjuvant radiation.

FTY720, sphingosine 1-phosphate receptor modulator, selectively radioprotects hippocampal neural stem cells.

Cranial irradiation is an effective treatment modality for both primary and metastatic brain tumors, yet it induces cognitive decline in a substantial number of patients. At present, there are no established methods for neuroprotection. Recent investigations have revealed a link between radiation-induced cognitive dysfunction and the loss of neural precursor cells in the hippocampus. Hence, identifying pharmacological agents, capable of protecting this cell population, is of interest. FTY720 (fingolimod), an FDA-approved oral drug for the treatment of multiple sclerosis, has been shown to promote the survival and differentiation of neural progenitors, as well as remyelination and repair after brain injury. In this study, we show that FTY720, used at nanomolar concentrations, is capable of increasing the viability and neurogenicity of irradiated neural stem cells from the hippocampus. In contrast, it does not provide radioprotection in a human breast cancer cell line and two glioma cell lines. These results suggest a potential therapeutic role for FTY720 as a neuroprotector during cranial irradiation. Further preclinical studies are warranted to evaluate this possibility.

Demographic disparities in patterns of care and survival outcomes for patients with resected gastric adenocarcinoma.

BACKGROUND: Several reports showed incomplete adoption of adjuvant radiotherapy (RT) for resectable gastric cancer since the publication of Intergroup 0116 trial results. The aims of this study were to identify demographic factors associated with omission of adjuvant RT and assess the impact of this omission on survival. METHODS: SEER database was queried for cases of resected gastric cancer. Multivariate analyses with logistic and Cox regressions were used to examine (a) likelihood of receiving adjuvant RT for different patient and county demographics and (b) effect of demographics on survival outcomes. RESULTS: A total of 7,348 patients met the study criteria. Adjuvant RT was used in 33.1% of cases diagnosed in 1998-2001 and in 45.3% of cases in 2002-2007 (P < 0.001). Controlling for independent covariates, African Americans were 8.9% less likely to receive adjuvant RT than Caucasians or Asians (P < 0.001). Correspondingly, overall survival rates were significantly lower for African Americans than other races (HR = 1.38, P < 0.001). Furthermore, both the likelihood of receiving RT and the survival rates were significantly affected by county demographics: percent of population without high school education, percent of households below the poverty line, and median household income. Survival rates were highest among Asians, but this finding did not reflect more frequent use of RT. CONCLUSIONS: Race and socioeconomic factors are significant predictors of treatment and survival outcomes for patients with resectable gastric cancer. IMPACT: The findings of this and similar studies may aide the medical community in designing more effective strategies to ameliorate the standards of care nationwide.

Neoadjuvant radiation is associated with improved survival in patients with resectable pancreatic cancer: an analysis of data from the surveillance, epidemiology, and end results (SEER) registry.

PURPOSE: Cancer of the exocrine pancreas is the fifth leading cause of cancer death in the United States. Neoadjuvant chemoradiation has been investigated in several trials as a strategy for downstaging locally advanced disease to resectability. The aim of the present study is to examine the effect of neoadjuvant radiation therapy (RT) vs. other treatments on long-term survival for patients with resectable pancreatic cancer in a large population-based sample group. METHODS AND MATERIALS: The Surveillance, Epidemiology, and End Results (SEER) registry database (1994-2003) was queried for cases of surgically resected pancreatic cancer. Retrospective analysis was performed. The endpoint of the study was overall survival. RESULTS: Using Kaplan-Meier analysis we found that the median overall survival of patients receiving neoadjuvant RT was 23 months vs. 12 months with no RT and 17 months with adjuvant RT. Using Cox regression and controlling for independent covariates (age, sex, stage, grade, and year of diagnosis), we found that neoadjuvant RT results in significantly higher rates of survival than other treatments (hazard ratio [HR], 0.55; 95% confidence interval, 0.38-0.79; p = 0.001). Specifically comparing adjuvant with neoadjuvant RT, we found a significantly lower HR for death in patients receiving neoadjuvant RT rather than adjuvant RT (HR, 0.63; 95% confidence interval, 0.45-0.90; p = 0.03). CONCLUSIONS: This analysis of SEER data showed a survival benefit for the use of neoadjuvant RT over surgery alone or surgery with adjuvant RT in treating pancreatic cancer. Therapeutic strategies that use neoadjuvant RT should be further explored for patients with resectable pancreatic cancer.

"Soluble" adenylyl cyclase-generated cyclic adenosine monophosphate promotes fast migration in PC12 cells.

In a model for neuronal movement, PC12 cells undergo fast migration in response to nerve growth factor (NGF) and phorbol ester (PMA). We previously showed that NGF increases intracellular cAMP via activation of soluble adenylyl cyclase (sAC). In this report, we demonstrate that sAC activation is an essential component of NGF- + PMA-induced fast migration in PC12 cells. Interestingly, PMA also raises intracellular cAMP but does so by stimulating transmembrane adenylyl cyclases (tmAC); however, this tmAC-generated cAMP does not contribute to fast migration. Therefore, cells must possess independent pools of cAMP capable of modulating distinct functions.

Soluble adenylyl cyclase mediates nerve growth factor-induced activation of Rap1.

Nerve growth factor (NGF) and the ubiquitous second messenger cyclic AMP (cAMP) are both implicated in neuronal differentiation. Multiple studies indicate that NGF signals to at least a subset of its targets via cAMP, but the link between NGF and cAMP has remained elusive. Here, we have described the use of small molecule inhibitors to differentiate between the two known sources of cAMP in mammalian cells, bicarbonate- and calcium-responsive soluble adenylyl cyclase (sAC) and G protein-regulated transmembrane adenylyl cyclases. These inhibitors, along with sAC-specific small interfering RNA, reveal that sAC is uniquely responsible for the NGF-elicited rise in cAMP and is essential for the NGF-induced activation of the small G protein Rap1 in PC12 cells. In contrast and as expected, transmembrane adenylyl cyclase-generated cAMP is responsible for Rap1 activation by the G protein-coupled receptor ligand PACAP (pituitary adenylyl cyclase-activating peptide). These results identify sAC as a mediator of NGF signaling and reveal the existence of distinct pathways leading to cAMP-dependent signal transduction.