Disparate Use of Chemoradiation in Elderly Patients With Localized Anal Cancer.

BACKGROUND: The incidence of squamous cell carcinoma of the anus (SCCA) is increasing, particularly among the elderly (age ≥65 years). We sought to compare patterns of care for the treatment of SCCA in elderly versus nonelderly patients. METHODS: Data for patients with stages I-III SCCA diagnosed from 2004 through 2015 were obtained from the National Cancer Database. Patients were categorized as having received standard-of-care (SOC) chemoradiation (CRT) with multiagent chemotherapy, non-SOC therapy, palliative therapy, or no treatment. Differences in treatment groups were tested using the chi-square test. We used logistic regression to identify predictors of SOC CRT and multiagent versus single-agent chemotherapy in patients receiving CRT. Propensity score matching was used to compare overall survival (OS) in elderly patients receiving multiagent versus single-agent chemotherapy for those receiving CRT. RESULTS: We identified 9,156 elderly and 17,640 nonelderly patients. A lower proportion of elderly versus nonelderly patients (54.5% vs 65.0%; P<.0001) received SOC CRT than other treatments or no treatment. In multivariate analysis, elderly patients were 38% less likely than nonelderly patients to receive SOC CRT (odds ratio, 0.62; 95% CI, 0.58-0.65; P<.0001). A higher proportion of the elderly were treated with single-agent versus multiagent chemotherapy (16.9% vs 11.8%; P<.0001), which resulted in a >1.5-fold increase in the likelihood of elderly patients receiving single-agent chemotherapy (odds ratio, 1.52; 95% CI, 1.39-1.66) in multivariate analysis. After propensity score matching, 3-year OS was higher in elderly patients who received CRT with multiagent versus single-agent chemotherapy (77.1% vs 67.5%; hazard ratio, 0.78; 95% CI, 0.68-0.89; P=.0002). CONCLUSIONS: In this comprehensive study of patients with stages I-III SCCA, elderly patients were less likely than nonelderly patients to receive SOC CRT. The low proportion of elderly patients receiving SOC CRT with multiagent chemotherapy for localized anal cancer suggests that the optimal treatment approach for this vulnerable population remains undefined.

Glioblastoma Recurrence Versus Treatment Effect in a Pathology-Documented Series.

OBJECTIVE: Patients diagnosed with glioblastoma (GBM) are treated with surgery followed by fractionated radiotherapy with concurrent and adjuvant temozolomide. Patients are monitored with serial magnetic resonance imaging (MRI). However, treatment-related changes frequently mimic disease progression. We reviewed a series of patients undergoing surgery for presumed first-recurrence GBM, where pathology reports were available for tissue diagnosis, in order to better understand factors associated with a diagnosis of treatment-related changes on final pathology. METHODS: Patient records at a single institution between 2005 and 2015 were retrospectively reviewed. Pathology reports were reviewed to determine diagnosis of recurrent GBM or treatment effect. Survival analysis was performed interrogating overall survival (OS) and progression-free survival (PFS). Correlation with radiation treatment plans was also examined. RESULTS: One-hundred-twenty-three patients were identified. One-hundred-sixteen patients (94%) underwent resection and seven underwent biopsy. Treatment-related changes were reported in 20 cases (16%). These patients had longer median OS and PFS from the time of recurrence than patients with true disease progression. However, there was no significant difference in OS from the time of initial diagnosis. Treatment effect was associated with surgery within 90 days of completing radiation. In patients receiving radiation at our institution (n = 53), larger radiation target volume and a higher maximum dose were associated with treatment effect. CONCLUSION: Treatment effect was associated with surgery nearer to completion of radiation, a larger radiation target volume, and a higher maximum point dose. Treatment effect was associated with longer PFS and OS from the time of recurrence, but not from the time of initial diagnosis.

Long-term Clinical Outcomes and Safety Profile of SBRT for Centrally Located NSCLC.

PURPOSE: Previous studies suggest that stereotactic body radiation therapy (SBRT) is associated with higher toxicity rates for central lung tumors relative to peripheral tumors when using 3 fraction SBRT. The initial results from Radiation Therapy Oncology Group study 0813 suggest a safe toxicity profile of SBRT administered in 5 fractions for central non-small cell lung cancer (NSCLC). We reviewed our institutional data to evaluate the safety and efficacy of SBRT for central NSCLC. METHODS AND MATERIALS: We reviewed our prospectively collected SBRT database for patients with central NSCLC who received SBRT between 2008 and 2014. The most frequent dose and fractionations were 50 Gy in 5 fractions (59%) and 48 Gy in 4 fraction (30%). Local control (LC), regional control, metastasis-free survival, and overall survival were calculated using Kaplan-Meier estimates. The National Cancer Institute Common Terminal Criteria for Adverse Events were used for toxicity grading. RESULTS: A total of 110 central lung tumors in 103 patients were included. The median age was 74 years (range, 40-95 years), and the median follow-up time of living patients was 50 months. The mean tumor size was 20 mm (range, 5-70 mm). The 5 year rate of LC, regional control, and distant control was 89%, 77%, and 82%, respectively. The median and 5-year overall survival were 3.5 years and 35%, respectively. No treatment variables were associated with tumor control or other clinical outcomes. A single patient experienced grade 3 radiation pneumonitis (0.97%). The rate of late toxicity grade ≥3 was 9.7% (grade 3, 7.7%; grade 4, 0.97%; grade 5, 0.97%) and included pneumonitis (3.9%), bronchial necrosis (2.9%), myocardial dysfunction (1.9%), and worsening heart failure (0.97%). CONCLUSIONS: SBRT for central NSCLC provides high rates of LC. Despite excellent LC, patients remain at risk for regional and distant failure. The rate of grade 3 pneumonitis was consistent with that of prior reports. We observed low rates of grade 4-5 toxicity potentially attributable to SBRT. Our results contribute to the growing body of data in support of the safety of SBRT for central NSCLC.

Validation of a Nomogram Predicting Survival After Trimodality Therapy for Esophageal Cancer.

BACKGROUND: Recently, a nomogram was developed for the prediction of overall survival (OS) after treatment with neoadjuvant chemoradiotherapy (nCRT) combined with surgery for esophageal or junctional cancer. The nomogram included clinical nodal category, pathologic tumor category, and number of positive lymph nodes in the resection specimen. The aim of this study was to externally validate the nomogram in an international multiinstitutional cohort of patients, and to explore the prognostic use of the nomogram for the prediction of progression-free survival (PFS) after nCRT plus surgery. METHODS: Patients with potentially resectable esophageal or junctional carcinoma that underwent nCRT plus surgery between 1998 and 2015 at 3 academic centers were included. The discriminative ability of the nomogram for the prediction of OS and PFS was quantified by Harrell's C-statistic. Calibration of the nomogram was visually assessed by plotting actual OS and PFS probabilities against predicted probabilities. RESULTS: Some 975 patients were included. The discriminative ability of the nomogram for OS was moderate (C-statistic, 0.61) and comparable to that of the initial cohort (C-statistic, 0.63). The nomogram was also useful for the prediction of PFS (C-statistic, 0.64). Calibration of the nomogram was accurate for both OS and PFS, with predicted estimates corresponding closely with the actual observed estimates. CONCLUSIONS: The nomogram accurately predicted OS and PFS after nCRT plus surgery in an independent international cohort of esophageal cancer patients. The current validated model may enable risk-stratified adjuvant treatment allocation and identify patients in need of routine surveillance after treatment.

Increased utilization of external beam radiotherapy relative to cystectomy for localized, muscle-invasive bladder cancer: a SEER analysis.

OBJECTIVE: To assess recent utilization patterns of radiotherapy (RT) relative to cystectomy for muscle-invasive bladder cancer (MIBC) and evaluate survival trends over time in patients receiving RT. MATERIALS AND METHODS: The surveillance, epidemiology, and end results program (SEER) was used to identify patients diagnosed between 1992 and 2013 with localized MIBC. Patients with a prior history of non-bladder malignancy, who received no treatment, or did not have available treatment information, were excluded. Treatment utilization patterns were assessed using Cochran-Armitage tests for trend, and patient characteristics were compared using chi-square tests. Overall survival (OS) and cause-specific survival (CSS) were estimated using the Kaplan-Meier method. All-cause (ACM) and cause-specific mortality (CSM) were evaluated with multivariable Cox proportional hazards regression. RESULTS: Of 16175 patients analyzed, 11917 (74%) underwent cystectomy, and 4258 (26%) were treated with RT. Patients who received RT were older (median age 79 vs. 68, P < 0.01). Over time, the proportion of patients receiving RT relative to cystectomy increased (24% 1992-2002 vs. 28% 2003-2013, P < 0.01), despite median patient age throughout the study period remaining unchanged (71 for each 1992-2002 and 2003-2013, P = 0.41). For RT, compared with patients diagnosed earlier, those diagnosed from 2010-2013 showed improved OS (64% vs. 60% at 1 year, P < 0.01; 38% vs. 29% at 3 years, P < 0.01) and CSS (71% vs. 67% at 1 year, P = 0.01; 51% vs. 40% at 3 years, P < 0.01). On multivariable analysis, diagnosis from 2010-2013 was associated with a lower estimated risk of ACM (hazard ratio 0.77; 95% confidence interval 0.66-0.89, P < 0.001) and CSM (hazard ratio 0.81; 95% confidence interval 0.67-0.97, P = 0.02). CONCLUSION: Utilization of RT for localized MIBC increased relative to cystectomy from 1992 to 2013, despite the median age of treated patients remaining unchanged. More recent survival outcomes for patients receiving RT were improved, supporting continued use of bladder preservation strategies utilizing RT.

Gamma Knife Stereotactic Radiosurgery for the Treatment of Primary and Metastatic Ocular Malignancies.

BACKGROUND: Gamma knife radiosurgery (GKR) can be used for precise targeting of malignant lesions of the CNS when brachytherapy is not an appropriate option. OBJECTIVES: This study reports treatment technique, efficacy, and radiation-induced adverse effects in patients with primary and metastatic ocular lesions treated with Leksell GKR. METHODS: A retrospective, single-institution review was conducted of 28 patients with primary or metastatic ocular disease, treated from 2000 to 2014. The dose to margin was 17-27 Gy (maximum dose 28-54 Gy). Primary outcomes included overall survival (OS), local control, progression-free survival (PFS), and enucleation. RESULTS: The median age at diagnosis was 70 years, and the median follow-up was 26.4 months. Of the 28 patients, 11 (39%) had metastatic ocular disease, and 17 (61%) were diagnosed with primary ocular melanoma (stage T2a-T4e). The average maximum dose and dose to margin were 41 and 21 Gy, respectively. The mean dose to the optic nerve was 12.6 Gy. The 5-year OS was 46% (95% CI: 23.6-68.4%) for the entire cohort; the 5-year PFS for M0 patients who presented with primary ocular melanoma lesions was 90% (95% CI: 71-100%). Only 1 patient required enucleation after radiation treatment. CONCLUSION: GKR is an effective option, with acceptable levels of toxicity, in the treatment of primary and metastatic ocular lesions.

18F-FDG PET response and clinical outcomes after stereotactic body radiation therapy for metastatic melanoma.

BACKGROUND: Clinical data that support stereotactic body radiation therapy (SBRT) metastatic malignant melanoma (MM) are limited. Furthermore, functional imaging with 18F-fludeoxyglucose positron emission tomography (PET) may offer a more accurate post-SBRT assessment. Therefore, we assessed the clinical outcomes and metabolic response of metastatic MM after SBRT. METHODS AND MATERIALS: Patients with MM who were treated with SBRT and had pre- and post-PET scans (>1) were included in this study. A total of 390 pre- and post-SBRT PET/computed tomography (CT) scans for 80 metastases were analyzed. The PET metabolic response was evaluated per the PET Response Criteria in Solid Tumors (PERCIST), version 1.0, criteria. Single-fraction equivalent dose (SFED) was calculated as per the standard. The Kaplan-Meier method was used for estimates of overall survival (OS) and progression-free survival. The cumulative incidence method was used to estimate metastasis control (MC). A Wilcoxon test was used to compare survival estimates. The prognostic factors for MC and OS were assessed using the Cox proportional hazards model, and the Likelihood Ratio was also used for comparisons between groups. RESULTS: A median of 6 PET scans (range, 2-6 scans) was evaluated for each metastasis. The median SFED was 42.8 Gy (range, 18-56.4 Gy) and the median biologically effective dose was 254.4 Gy2.5 (range, 100.8-540 Gy2.5). Twenty percent of patients received chemotherapy and 59% received immunotherapy: granulocyte-macrophage colony-stimulating factor (64%) and ipilimumab (34%). MC was 94% and 90% at 1 year and 3 years, respectively. The OS was 74% and 27% and 1 year and 3 years, respectively. Complete response was achieved in 90% at a median of 2.8 months (range, 0.4-25.2 months). SFED >24 Gy correlated with improved MC (93% vs 75%, P = .01). Acute and late grade 3+ toxicities were 4% and 11%, respectively, with no grade 5 toxicity. CONCLUSIONS: Post-SBRT PET/CT for extracranial metastatic MM resulted in high rates of complete response at a median of 2.8 months, and durable MC was achieved with SFED >24 Gy. SBRT, in addition to surgery and ablation, should be discussed with patients with MM, especially those with oligometastases.

FDG-PET parameters as predictors of pathologic response and nodal clearance in patients with stage III non-small cell lung cancer receiving neoadjuvant chemoradiation and surgery.

OBJECTIVE: Pathologic complete response (pCR) following neoadjuvant chemoradiation (CRT) is associated with improved outcomes in stage III non-small cell lung cancer. Conflicting results exist regarding the value of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting pCR. This study evaluated the association between post-CRT FDG-PET and pCR using novel FDG-PET parameters. METHODS AND MATERIALS: This retrospective study included patients treated with CRT and resection. All underwent pre- and post-CRT FDG-PET imaging. Maximum standard uptake value (SUVmax), standard uptake ratio (SUR), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured. RESULTS: In total, 44 patients were included for review. The majority had cT2 disease (59.0%). Median radiation dose was 60 Gy (45-70.2 Gy). Rate of pCR and near-pCR within the primary lesion was 29.5% and 45.5%, respectively. Average reduction in SUVmax was 9.2, whereas SUR normalized to mediastinum and liver showed mean reductions of 4.7 and 3.5, respectively. No association was found between pCR and either MTV or TLG. Reduction in SUVmax and SUR were significantly associated with increased rate of pCR (P ≤ .02). A threshold of >75% decrease in SUR-liver showed significant association with near-pCR (diagnostic odds ratio [DOR]: 8.3; P = .007). No correlation was found between nodal FDG-PET parameters and nodal pCR. CONCLUSIONS: Our results indicate SUV and SUR have utility in predicting pCR after neoadjuvant CRT. SUR parameters trended toward higher DORs, suggesting improved predictive utility compared with SUVmax. Notably, no association was found with nodal pCR. Furthermore, MTV and TLG changes were not predictive, potentially resulting from inflammation after full-dose radiation, but this warrants further investigation.

Gamma knife radiosurgery for the treatment of uveal melanoma and uveal metastases.

BACKGROUND: This study retrospectively analyzed outcomes for patients undergoing gamma knife radiosurgery (GKR) for uveal melanoma (UM) and intraocular metastases. METHODS: Patients who underwent GKR for UM or intraocular metastases between 1/1/1990 and 6/1/2015 at Mayo Clinic, Rochester, MN, USA, were retrospectively analyzed. RESULTS: Eleven patients (11 eyes) had UM while seven patients (7 eyes) had intraocular metastases. Patients with UM were followed for a median of 19.74 ± 10.4 months. Visual acuity (VA) logMAR 0.30 ± 0.53 (Snellen 20/40) versus 0.40 ± 0.97 (Snellen 20/50), tumor thickness (5.30 ± 2.17 vs. 3.60 ± 2.32 mm), were not significantly different between preoperative and postoperative measurements, respectively. Nine percent (1/11) patients required enucleation. Subsequently, no patients experienced metastases. Patients with intraocular metastases were followed for a median of 6.03 ± 6.32 months. They did not have significant changes in VA (logMAR 0.30 ± 0.59 vs. 0.30 ± 1.57; Snellen 20/40 vs. 20/40) or tumor thickness (3.50 ± 1.36 vs. 1.30 ± 0.76 mm) postoperatively. Fourteen percent (1/7 patients) required enucleation. Complications experienced by patients with UM include radiation retinopathy (2/11), papillopathy (1/11), cystoid macular edema (1/11), vitreomacular traction (1/11), exudative retinal detachment (1/11). Patients with metastases had treatment complicated by recurrence (2/7). Dose to the margin, maximum dose of radiation, and clinical target volume did not correlate with post-procedural VA, risk of enucleation, or death in patients with either UM or patients with intraocular metastases. CONCLUSIONS: Visual outcomes were satisfactory for patients undergoing GKR without significant morbidity and without significant risk of enucleation or metastases.

A Multi-institutional Analysis of Trimodality Therapy for Esophageal Cancer in Elderly Patients.

PURPOSE: The therapeutic gains of neoadjuvant chemoradiation therapy (nCRT) followed by esophagectomy may be offset by increased incidences of morbidity and mortality in elderly patients. This study aimed to determine the impact of age on the risks and benefits of trimodality therapy for esophageal cancer. METHODS AND MATERIALS: We evaluated 571 patients treated with trimodality therapy at 3 high-volume tertiary cancer centers in the United States from 2007 to 2013. Two hundred two of 571 (35%) patients were 65 years or older at diagnosis and were classified as elderly. Toxicity and treatment parameters for the elderly cohort were compared with the younger cohort (ages 22-64) by the use of univariate (UVA) and multivariable (MVA) logistic analyses. Age was analyzed as a continuous hazard for cardiac and pulmonary toxicities. Survival was assessed by the Kaplan-Meier method. RESULTS: Elderly patients had a higher risk for postoperative cardiac toxicities (UVA: odds ratio [OR] 2.2, P<.001; MVA: OR 2.07, P=.004) and pulmonary toxicities (UVA: OR 2.0, P<.001; MVA: OR 2.03, P<.001) and a higher 90-day postoperative mortality (5.4% vs 2.2%, P=.049). Of the elderly patients, 6.9% experienced acute respiratory distress syndrome compared with 3.8% of younger patients (P=.11). Cardiac toxicity was linearly associated with age, and the relative risk increased by 61% for every additional decade of age. There was no difference in postoperative gastrointestinal or wound adverse events or in length of hospital stay. Grade 3+ acute toxicities from nCRT were infrequent and were clinically similar regardless of age. Freedom from esophageal cancer and disease-free survival were similar, but overall survival was significantly shorter in the elderly cohort. CONCLUSIONS: Elderly patients experienced more postoperative cardiopulmonary toxicities and mortality than did younger patients after nCRT. Compared with contemporary outcomes for trimodality therapy, both cohorts had acceptable rates for adverse events and disease control. For appropriately selected elderly patients, trimodality therapy for esophageal cancer is a reasonable treatment option.

Utility of 18F-FDG PET for Predicting Histopathologic Response in Esophageal Carcinoma following Chemoradiation.

INTRODUCTION: For patients with esophageal cancer undergoing neoadjuvant chemoradiation (CRT) followed by surgical resection, complete histopathologic response (pCR) is associated with favorable overall survival (OS). The aim of this study was to evaluate the correlation between 18F-fluorodeoxyglucose positron emission tomography (FDG PET) response to neoadjuvant CRT and pCR. METHODS: Maximum standardized uptake values and standardized uptake ratios (SURs) were measured before and after CRT. SUR was normalized to liver uptake and mediastinal blood pool uptake. FDG PET complete response was defined as metabolic activity normalization to hepatic and blood pool activity. The correlation between FDG PET parameters and pCR was examined through logistic regression analyses. RESULTS: In total, 193 patients were monitored for a median of 3.6 years after initiation of CRT. Most tumors were adenocarcinoma (85%) and stage T3 (75%). Complete FDG PET response and pCR occurred in 27% and 34% of patients, respectively. Histologic findings, chemotherapy type, tumor stage, and radiation dose were not significantly associated with complete radiographic response. The rates of pCR in patients with and without radiographic complete response were 42% and 31% (p = 0.17), respectively. No predictive correlation was found between pCR and change in maximum standardized uptake value (p = 0.25), in SUR normalized to blood pool uptake (p = 0.20), or in SUR normalized to liver uptake (p = 0.15). The 5-year OS rate was 46% for patients with a complete FDG PET response versus 44% without a complete response (p = 0.78). The 5-year OS rate of patients who achieved pCR was 49% versus 43% for patients with residual tumor (p = 0.04). CONCLUSION: For patients with esophageal cancer who received neoadjuvant chemoradiation, pretreatment and posttreatment FDG PET parameters did not correlate with pCR or OS.

Genome-based Mutational Analysis by Next Generation Sequencing in Patients with Malignant Pleural and Peritoneal Mesothelioma.

BACKGROUND/AIM: Malignant mesothelioma is a rare malignancy with limited therapeutic options. Exome-based next-generation sequencing (NGS) techniques may direct the future of molecular targeting and improve systemic therapies for patients with mesothelioma. MATERIALS AND METHODS: Eleven patients with NGS testing were selected, with a total of 236 somatic cancer-related mutations analyzed. Descriptive and Kaplan-Meier statistics were applied. RESULTS: The median age was 65 years (range=27-73 years); 4 (36%) patients were females. Seven (64%) and four patients (36%) had pleural and peritoneal mesothelioma, respectively. Detectable mutations were found in 86% of the pleural and 50% of the peritoneal mesothelioma patients (overall, 73% of patients). The families of BAP1 (36%), CDKNA2A/B (27%) and NF2 (27%) represented the most frequently mutated genes. The median overall survival for all patients was 20.8 months, with 1- and 2-year survival rates of 91% and 40%, respectively. CONCLUSION: Genomic alterations as potential therapeutic targets were found by NGS. These findings will help in the development of new screening tools and targeting therapies, and in turn impact the standard-of-care and potentially lengthen disease control and survival periods in the future.

Phosphorylation within the cysteine-rich region of dystrophin enhances its association with ß-dystroglycan and identifies a potential novel therapeutic target for skeletal muscle wasting.

Mutations in dystrophin lead to Duchenne muscular dystrophy, which is among the most common human genetic disorders. Dystrophin nucleates assembly of the dystrophin-glycoprotein complex (DGC), and a defective DGC disrupts an essential link between the intracellular cytoskeleton and the basal lamina, leading to progressive muscle wasting. In vitro studies have suggested that dystrophin phosphorylation may affect interactions with actin or syntrophin, yet whether this occurs in vivo or affects protein function remains unknown. Utilizing nanoflow liquid chromatography mass spectrometry, we identified 18 phosphorylated residues within endogenous dystrophin. Mutagenesis revealed that phosphorylation at S3059 enhances the dystrophin-dystroglycan interaction and 3D modeling utilizing the Rosetta software program provided a structural model for how phosphorylation enhances this interaction. These findings demonstrate that phosphorylation is a key mechanism regulating the interaction between dystrophin and the DGC and reveal that posttranslational modification of a single amino acid directly modulates the function of dystrophin.

Immune Responses to rAAV6: The Influence of Canine Parvovirus Vaccination and Neonatal Administration of Viral Vector.

Recombinant adeno-associated viral (rAAV) vectors promote long-term gene transfer in many animal species. Significant effort has focused on the evaluation of rAAV delivery and the immune response in both murine and canine models of neuromuscular disease. However, canines provided for research purposes are routinely vaccinated against canine parvovirus (CPV). rAAV and CPV possess significant homology and are both parvoviruses. Thus, any immune response generated to CPV vaccination has the potential to cross-react with rAAV vectors. In this study, we investigated the immune response to rAAV6 delivery in a cohort of CPV-vaccinated canines and evaluated multiple vaccination regimens in a mouse model of CPV-vaccination. We show that CPV-vaccination stimulates production of neutralizing antibodies with minimal cross-reactivity to rAAV6. In addition, no significant differences were observed in the magnitude of the rAAV6-directed immune response between CPV-vaccinated animals and controls. Moreover, CPV-vaccination did not inhibit rAAV6-mediated transduction. We also evaluated the immune response to early rAAV6-vaccination in neonatal mice. The influence of maternal hormones and cytokines leads to a relatively permissive state in the neonate. We hypothesized that immaturity of the immune system would permit induction of tolerance to rAAV6 when delivered during the neonatal period. Mice were vaccinated with rAAV6 at 1 or 5 days of age, and subsequently challenged with rAAV6 exposure during adulthood via two sequential IM injections, 1 month apart. All vaccinated animals generated a significant neutralizing antibody response to rAAV6-vaccination that was enhanced following IM injection in adulthood. Taken together, these data demonstrate that the immune response raised against rAAV6 is distinct from that which is elicited by the standard parvoviral vaccines and is sufficient to prevent stable tolerization in neonatal mice.

Expression of the dystrophin isoform Dp116 preserves functional muscle mass and extends lifespan without preventing dystrophy in severely dystrophic mice.

Dp116 is a non-muscle isoform of dystrophin that assembles the dystrophin-glycoprotein complex (DGC), but lacks actin-binding domains. To examine the functional role of the DGC, we expressed the Dp116 transgene in mice lacking both dystrophin and utrophin (mdx:utrn(-/-)). Unexpectedly, expression of Dp116 prevented the most severe aspects of the mdx:utrn(-/-) phenotype. Dp116:mdx:utrn(-/-) transgenic mice had dramatic improvements in growth, mobility and lifespan compared with controls. This was associated with increased muscle mass and force generating capacity of limb muscles, although myofiber size and specific force were unchanged. Conversely, Dp116 had no effect on dystrophic injury as determined by muscle histopathology and serum creatine kinase levels. Dp116 also failed to restore normal fiber-type distribution or the post-synaptic architecture of the neuromuscular junction. These data demonstrate that the DGC is critical for growth and maintenance of muscle mass, a function that is independent of the ability to prevent dystrophic pathophysiology. Likewise, this is the first demonstration in skeletal muscle of a positive functional role for a dystrophin protein that lacks actin-binding domains. We conclude that both mechanical and non-mechanical functions of dystrophin are important for its role in skeletal muscle.

Therapy for neuromuscular disorders.

Research into therapeutic approaches for both recessive and dominant neuromuscular disorders has made great progress over the past few years. In the field of gene therapy, antisense-mediated exon skipping is being applied to bypass deleterious mutations in the dystrophin gene and restore dystrophin expression in animal models of muscular dystrophy. Approaches for the dominant genetic muscle diseases have turned toward elimination of the mutant gene product with anti-sense oligonucleotide therapy and RNA interference techniques. Refinements of adeno-associated viral vectors and strategies for their delivery are also leading towards future clinical trials. The discovery of new, multipotent cell lineages, some of which possess the ability to successfully engraft muscle following vascular delivery, presents exciting prospects for the field of stem cell therapy. These discoveries represent steady progress towards the development of effective therapies for a wide range of neuromuscular disorders.

Antisense oligonucleotide against GTPase Rab5b inhibits metabotropic agonist DHPG-induced neuroprotection.

(S)-3,5-dihydroxyphenylglycine (DHPG), a group I metabotropic glutamate receptor (mGluR1 and 5) agonist reduced NMDA-mediated membrane currents, NMDA-induced cell death and up-regulated Rab5b, a small GTPase involved in endocytosis [M. Blaabjerg, A. Baskys, J. Zimmer and M. P. Vawter, Changes in hippocampal gene expression after neuroprotective activation of group I metabotropic glutamate receptors, Molec. Brain Res. 117 (2003) 196-205; M. Blaabjerg, L. Fang, J. Zimmer and A. Baskys, Neuroprotection against NMDA excitotoxicity by group I metabotropic glutamate receptors is associated with reduction of NMDA stimulated currents, Experimental Neurol. 183 (2003) 573-580.]. To examine the role of Rab5b on DHPG-mediated neuroprotection in organotypic hippocampal cultures, we developed antisense oligonucleotide targeted to suppress Rab5b translation. Treatment of cultures with the antisense (24 h) but not scrambled sequence oligonucleotide suppressed DHPG-induced increase in Rab5b expression and significantly disrupted DHPG-induced protection against NMDA toxicity in a concentration-dependent manner (0.01-10 nM). Antisense but not scrambled oligonucleotide treatment reduced NMDA toxicity (to 74.4+/-5.9% of control) and this effect could be blocked by protein kinase C inhibitor staurosporine (0.2 microM) or with the protease inhibitor leupeptin (100 microM). Application of osmotic shock followed by K(+) depletion to disrupt endocytosis abolished the protective effect of DHPG. These data suggest that neuroprotection by DHPG against NMDA-mediated injury may involve facilitation of NMDA receptor endocytosis likely stimulated by DHPG-induced increase in Rab5b synthesis.