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.

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.

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.

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.