Challenges and Opportunities With the Use of Hypofractionated Radiation Therapy in Cancer Care: Regional Perspectives From South Korea, Japan, Singapore, and Australia

Hypofractionated radiotherapy schedules provide higher per-fraction radiation doses delivered in fewer fractions than conventional schedules. This novel delivery method is supported by a large body of clinical trial evidence across various cancer sites in both curative and palliative settings. Hypofractionation is associated with benefits such as lower costs, improved patient access and increased treatment precision, which has led to its inclusion in various treatment guidelines. Despite this, utilization is not uniform across cancer sites and geographic regions due to reasons such as reimbursement models, nuances in healthcare systems, and professional culture. Key factors to ensure patients benefit from access to high quality radiotherapy include publishing clinical evidence, cross-country collaboration to fill knowledge gaps, reviewing reimbursement models, and improving patient advocacy in treatment decision-making.

Post-mastectomy Radiation Therapy in HER-2 Positive Breast Cancer after Primary Systemic Therapy: Pooled Analysis of TRYPHAENA and NeoSphere Trials

PURPOSE

The role of post-mastectomy radiation therapy (PMRT) following primary systemic therapy (PST) in HER-2 positive breast cancer (Her2+BC) remains poorly understood. The current study evaluates PMRT based on the pathological response to PST in Her2+BC.

METHODS AND MATERIALS

TRYPHAENA and NeoSphere are randomized phase II trials that investigated PST for Her2+BC. Our study is a pooled analysis of both trials, including 312 node-positive patients treated with HER-2 targeted PST followed by mastectomy with or without PMRT. The primary endpoint is loco-regional recurrence-free survival (LRRFS).

RESULTS

Our analysis included 172 (55%) patients who achieved complete nodal pathological response (ypN0) and 140 (45%) patients who did not. Patients with ypN0 had a 5-year LRRFS of 97% in both, the PMRT and no PMRT, groups (p=0.94). Patients with ypN+ had 5-year LRRFS of 89% in the PMRT group and 82% in the no PMRT group (p=0.17). Patients with ypN1 (n=62) disease who received PMRT (n=40) had a 5-year LRRFS of 85% as compared to 89% in those who did not (n=22); (p=0.60). A significant LRRFS difference was noted in patients with ypN2-3 (n=78) disease who received PMRT (n=53) compared to those who did not (n=25) (5-year LRRFS 92% vs. 75%; p=0.019). On multivariate analysis, clinical nodal disease at diagnosis and ypN0 were significantly associated with loco-regional recurrence (LRR).

CONCLUSIONS

Her2+BC patients who achieve ypN0 after PST have excellent locoregional-control which supports de-escalation of PMRT. In contrast, patients with ypN2-3 disease derive significant benefit from PMRT. Clinical nodal stage at presentation and ypN0 status are significantly associated with LRR risk in Her2+BC.

A phase II single arm study of Nivolumab with stereotactic Ablative radiation Therapy after induction chemotherapy in CHOlangiocarcinoma (NATCHO)

BACKGROUND

Intrahepatic cholangiocarcinoma (CCA) is amongst the most common primary liver tumors worldwide. CCA carries a bad prognosis prompting research to establish new treatment modalities other than surgery and the current chemotherapeutic regimens adopted. Hence, this trial explores a new therapeutic approach, to combine stereotactic body radiation therapy (SBRT) and immunotherapy (Nivolumab), and asses its clinical benefit and safety profile after induction chemotherapy in CCA.

METHODOLOGY

This is a Phase II open-label, single-arm, multicenter study that investigates Nivolumab (PD-1 inhibitor) treatment at Day 1 followed by SBRT (30 Gy in 3 to 5 fractions) at Day 8, then monthly Nivolumab in 40 patients with non-resectable locally advanced, metastatic or recurrent intrahepatic or extrahepatic CCA. Eligible patients were those above 18 years of age with a pathologically and radiologically confirmed diagnosis of non-resectable locally advanced or metastatic or recurrent intrahepatic or extrahepatic CCA, following 4 cycles of cisplatin-based chemotherapy with an estimated life expectancy of more than 3 months, among other criteria. The primary endpoint is the progression free survival (PFS) rate at 8 months and disease control rate (DCR). The secondary endpoints are overall survival (OS), tumor response rate (TRR), duration of response, evaluation of biomarkers: CD3 + , CD4 + and CD8 + T cell infiltration, as well as any change in the PD-L1 expression through percutaneous core biopsy when compared with the baseline biopsy following 1 cycle of Nivolumab and SBRT.

DISCUSSION

SRBT alone showed promising results in the literature by both inducing the immune system locally and having abscopal effects on distant metastases. Moreover, given the prevalence of PD-L1 in solid tumors, targeting it or its receptor has become the mainstay of novel immunotherapeutic drugs use. A combination of both has never been explored in the scope of CCA and that is the aim of this study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04648319 , April 20, 2018.

Urinary 20-HETE: A prospective Non-Invasive prognostic and diagnostic marker for diabetic kidney disease

INTRODUCTION

The identification and validation of a non-invasive prognostic marker for early detection of diabetic kidney disease (DKD) can lead to substantial improvement in therapeutic decision-making.

OBJECTIVES

The main objective of this study is to assess the potential role of the arachidonic acid (AA) metabolite 20-hydroxyeicosatetraenoic (20-HETE) in predicting the incidence and progression of DKD.

METHODS

Healthy patients and patients with diabetes were recruited from the Hamad General Hospital in Qatar, and urinary 20-HETE levels were measured. Data analysis was done using the Statistical Package for Social Sciences (SPSS).

RESULTS

Our results show that urinary 20-HETE-to-creatinine (20-HETE/Cr) ratios were significantly elevated in patients with DKD when compared to patients with diabetes who did not exhibit clinical signs of kidney injury (p < 0.001). This correlation was preserved in the multivariate linear regression accounting for age, diabetes, family history of kidney disease, hypertension, dyslipidemia, stroke and metabolic syndrome. Urinary 20-HETE/Cr ratios were also positively correlated with the severity of kidney injury as indicated by albuminuria levels (p < 0.001). A urinary 20-HETE/Cr ratio of 4.6 pmol/mg discriminated between the presence and absence of kidney disease with a sensitivity of 82.2 % and a specificity of 67.1%. More importantly, a 10-unit increase in urinary 20-HETE/Cr ratio was tied to a 10-fold increase in the risk of developing DKD, suggesting a 20-HETE prognostic efficiency.

CONCLUSION

Taken together, our results suggest that urinary 20-HETE levels can potentially be used as non-invasive diagnostic and prognostic markers for DKD.

Is breast conservation superior to mastectomy in early stage triple negative breast cancer?

Purpose

Compare overall survival (OS) and breast cancer-specific survival (BCSS) outcomes of breast conservative therapy (BCT) and mastectomy in a large cohort of patients with early-stage triple negative breast cancer (TNBC), using a propensity score-based matching approach.

Methods

Surveillance, Epidemiology, and End Results (SEER) database was used to study the role of RT in early stage TNBC. Primary end points were OS and BCSS. Cox proportional hazard regression models and Kaplan-Meier plots were used to generate the desired outcomes. Propensity score matching was done to minimize bias.

Results

12,761 patients with T1-2N0M0 TNBC as their first malignancy were retrieved. Of these 7237 had lumpectomy with RT, and 5524 had mastectomy only. Age, race, marital status, tumor laterality, grade and stage, and receipt of chemotherapy were prognostic variables for OS and BCSS. Among 4848 matched subjects, the 5-year OS was significantly higher in patients with lumpectomy and RT (89%) compared to mastectomy alone (84.5%) (p-value <0.001). Similarly, BCSS was significantly higher in patients with lumpectomy and RT (93%) compared to mastectomy alone (91%) (p-value <0.001). On subgroup analysis, patients who are younger than 40 had similar survival outcomes after either mastectomy alone or lumpectomy with RT. However, those who are older than 60, have any grade or T stage had better survival outcomes with lumpectomy and RT.

Conclusions

Overall, lumpectomy followed by RT is associated with better OS and BCSS compared to mastectomy in T1-2N0M0 TNBC patients. Further research is needed to determine the optimal treatment strategy for specific patient subgroups.

•

BCT is associated with better OS compared to mastectomy in early-stage TNBC.

•

BCT is associated with better BCSS compared to mastectomy in early-stage TNBC.

•

Age, race, marital status, and grade/stage are prognostic for early-stage TNBC.

Evaluation of Cardiotoxicity in HER-2-Positive Breast Cancer Patients Treated With Radiation Therapy and Trastuzumab

PURPOSE

Trastuzumab is associated with cardiac dysfunction in patients with human epidermal growth factor receptor 2 (HER-2)-positive breast cancer. The current study examines the effect of radiation therapy (RT) on cardiotoxicity in this patient population.

METHODS AND MATERIALS

The Herceptin Adjuvant (HERA) trial is a phase 3 prospective, randomized clinical trial that established the efficacy of trastuzumab in HER-2-positive breast cancer. The current study is a retrospective analysis of 3321 trial patients treated with trastuzumab, with or without RT. Cardiac function was closely monitored over a median follow-up period of 11 years. The primary endpoint of the current study was to determine the effect of RT on left ventricular ejection fraction (LVEF) and the occurrence of cardiovascular events.

RESULTS

Patients were divided into 3 groups: 1270 patients received trastuzumab and left-sided RT (group 1); 1271 patients received trastuzumab and right-sided RT (group 2); and 780 patients received trastuzumab with no RT (group 3). The incidence of decline in LVEF documented by echocardiography was 9.18%, 8.99%, and 8.80%, respectively, with no significant differences among the 3 groups (P = .073). The incidence of cardiovascular events was low in all groups, with the lowest incidence noted in group 3 (0.62%) followed by group 2 (0.92%) and group 1 (1.08%) (P = .619). Univariate and multivariate competing-risks regression showed that left-sided and right-sided RT delivery did not significantly increase the risk of LVEF decline or cardiovascular events.

CONCLUSIONS

Our analysis of the HERA trial suggests that RT does not significantly increase the risk of cardiotoxicity in HER-2-positive breast cancer patients treated with trastuzumab. Continued monitoring of patients is needed to investigate late effects of contemporary treatments for breast cancer patients.

Crosstalk Between SMPDL3b and NADPH Oxidases Mediates Radiation-Induced Damage of Renal Podocytes

Patients undergoing radiotherapy (RT) for various tumors localized in the abdomen or pelvis often suffer from radiation nephrotoxicity as collateral damage. Renal podocytes are vulnerable targets for ionizing radiation and contribute to radiation-induced nephropathies. Our prior work previously highlighted the importance of the lipid-modifying enzyme sphingomyelinase acid phosphodiesterase like 3b (SMPDL3b) in modulating the radiation response in podocytes and glomerular endothelial cells. Hereby, we investigated the interplay between SMPDL3b and oxidative stress in mediating radiation injury in podocytes. We demonstrated that the overexpression of SMPDL3b in cultured podocytes (OE) reduced superoxide anion generation and NADPH oxidase activity compared to wild-type cells (WT) post-irradiation. Furthermore, OE podocytes showed downregulated levels of NOX1 and NOX4 after RT. On the other hand, treatment with the NOX inhibitor GKT improved WTs' survival post-RT and restored SMPDL3b to basal levels. in vivo, the administration of GKT restored glomerular morphology and decreased proteinuria in 26-weeks irradiated mice. Taken together, these results suggest a novel role for NOX-derived reactive oxygen species (ROS) upstream of SMPDL3b in modulating the response of renal podocytes to radiation.

Post-mastectomy Radiation Therapy in Triple-Negative Breast Cancer Patients: Analysis of the BEATRICE Trial

PURPOSE

Post-mastectomy radiation therapy (PMRT) improves locoregional control and overall survival in patients with breast cancer. With the evolution of systemic therapy, the benefit of PMRT in patients with triple-negative disease requires further evaluation.

PATIENTS AND METHODS

BEATRICE is a phase III randomized clinical trial that examined the efficacy of bevacizumab in patients with triple-negative breast cancer (TNBC). The current study is a retrospective analysis of data on patients enrolled and treated with mastectomy and systemic therapy. The primary endpoint was determining the effect of PMRT on locoregional recurrence rates (LRR). Hazard ratios were estimated using Cox regression, and LRR curves were generated by the Kaplan-Meier method.

RESULTS

In total, 940 patients were included in our analysis, of whom 359 (38.2%) received PMRT while 581 (61.8%) did not. At median follow-up of 5 years, no significant difference in LRR was noted between the PMRT and no PMRT groups in node-negative patients (HR = 1.09). Patients with N1 disease had 5-year LRR-free survival of 96% for PMRT versus 91% for no PMRT (HR = 0.46). Most N2 patients received PMRT and had 5-year LRR-free survival of 76%.

CONCLUSION

PMRT benefit in TNBC patients treated with modern systemic therapy is lower than historical reports. Delivery of PMRT in patients with N1 disease enrolled in the BEATRICE trial was not shown to improve local control. As this might be due to patient selection for PMRT, future randomized controlled trials are required to assess the role of PMRT in this patient population.

Oligometastatic breast cancer: Are we there yet?

Patients with metastatic breast cancer are usually considered incurable. Recent advances have resulted in significant improvements in survival for patients with metastatic breast cancer. Due to the lack of randomised trials and heterogeneous disease biology, treatment decisions for patients with oligometastatic breast cancer vary widely. Some patients are treated similar to those with widespread disease while others are treated more aggressively. We conducted a review of the evidence for treatment options in oligometastatic breast cancer and consulted ClinicalTrials.gov to explore currently accruing or studies in development aimed at investigating oligometastatic disease in breast cancer. Surgery to the primary tumour in patients with metastatic breast cancer has failed to show any advantage over systemic therapy. However, there may be a benefit in women with controlled systemic disease who are hormone receptor positive with bone-predominant metastasis. Stereotactic radiotherapy has gained increased interest in this setting due to its excellent efficacy and lower rates of associated toxicity. A significant challenge remains in identifying the patient population who would benefit from such an approach, and to do so, we need to understand the distinct biology of oligometastatic breast cancer. Unique miRNA expression and low levels of tumour infiltrating lymphocytes in the immune micro-environment have been described in tumour tissues in patients with oligometastatic breast cancer. There is ongoing research aimed to better characterise these tumours, thus, allowing the selection of patients who would truly benefit from multi-modality treatment in an attempt for long-term survival and cure.

Noninvasive assessment of radiation-induced renal injury in mice

PURPOSE

The kidney is a radiosensitive late-responding normal tissue. Injury is characterized by radiation nephropathy and decline of glomerular filtration rate (GFR). The current study aimed to compare two rapid and cost-effective methodologies of assessing GFR against more conventional biomarker measurements.

METHODS

C57BL/6 mice were treated with bilateral focal X-irradiation (1x14Gy or 5x6Gy). Functional measurements of kidney injury were assessed 20 weeks post-treatment. GFR was estimated using a transcutaneous measurement of fluorescein-isothiocyanate conjugated (FITC)-sinistrin renal excretion and also dynamic contrast-enhanced CT imaging with a contrast agent (ISOVUE-300 Iopamidol).

RESULTS

Hematoxylin and eosin (H&E) and Periodic acid-Schiff staining identified comparable radiation-induced glomerular atrophy and mesangial matrix accumulation after both radiation schedules, respectively, although the fractionated regimen resulted in less diffuse tubulointerstitial fibrosis. Albumin-to-creatinine ratios (ACR) increased after irradiation (1x14Gy: 100.4 ± 12.2 µg/mg; 6x5Gy: 80.4 ± 3.02 µg/mg) and were double that of nontreated controls (44.9 ± 3.64 µg/mg). GFR defined by both techniques was negatively correlated with BUN, mesangial expansion score, and serum creatinine. The FITC-sinistrin transcutaneous method was more rapid and can be used to assess GFR in conscious animals, dynamic contrast-enhanced CT imaging technique was equally safe and effective.

CONCLUSION

This study demonstrated that GFR measured by dynamic contrast-enhanced CT imaging is safe and effective compared to transcutaneous methodology to estimate kidney function.

Post-lumpectomy radiation therapy boost in breast cancer patients: evidence revisited

Purpose

Radiation therapy is an integral part in the management of breast cancer after breast conservative surgery. In selected patients at high risk for local recurrence (LR), a boost radiation dose is commonly applied to the tumour bed.

Methods

We performed a review of the English literature using PubMed, Medline and Google Scholar for published manuscripts addressing the effect of boost radiation in breast cancer patients, focusing mainly on LR and overall survival (OS).

Results

A total of seven studies were included in our review. Most studies (6/7, 85.7%) showed a significant improvement in local control independent of age (hazard ratios ranging between 0.34 and 0.73), with the largest absolute benefit in younger patients. None of the studies, however, was able to demonstrate an improvement in OS.

Conclusions

With lack of sufficient studies addressing the role of boost radiation, individualised treatment decisions are recommended, taking into account the risk factors for LR, including tumour biology. Real-life data are sorely needed to better assess the role of tumour bed boost in the contemporary era.

Radiation-induced neuropathies in head and neck cancer: prevention and treatment modalities

Head and neck cancer (HNC) is the sixth most common human malignancy with a global incidence of 650,000 cases per year. Radiotherapy (RT) is commonly used as an effective therapy to treat tumours as a definitive or adjuvant treatment. Despite the substantial advances in RT contouring and dosage delivery, patients suffer from various radiation-induced complications, among which are toxicities to the nervous tissues in the head and neck area. Radiation-mediated neuropathies manifest as a result of increased oxidative stress-mediated apoptosis, neuroinflammation and altered cellular function in the nervous tissues. Eventually, molecular damage results in the formation of fibrotic tissues leading to susceptible loss of function of numerous neuronal substructures. Neuropathic sequelae following irradiation in the head and neck area include sensorineural hearing loss, alterations in taste and smell functions along with brachial plexopathy, and cranial nerves palsies. Numerous management options are available to relieve radiation-associated neurotoxicities notwithstanding treatment alternatives that remain restricted with limited benefits. In the scope of this review, we discuss the use of variable management and therapeutic modalities to palliate common radiation-induced neuropathies in head and neck cancers.

Proton Therapy as a Bridging Treatment in CAR T-Cell Therapy for Relapsed and Refractory Large B-Cell Lymphoma: Is There a Role?

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. Since the relapse rate of DLBCL to frontline chemoimmunotherapy and salvage autologous hematopoietic cell transplant is high, CD19-directed chimeric antigen receptor (CAR) T-cell therapy was adopted. Given the time interval needed for CAR T cells to be manufactured (3-5 weeks) and the aggressiveness of these relapsed/refractory lymphomas, some patients do not make it to the CAR T-cell infusion phase. This calls for a bridging therapy to control, debulk, and sensitize the disease during this period. Radiation therapy can serve this purpose and has shown promising results in some studies. Proton therapy, compared to standard radiation therapy, in some locations, can reduce the radiation dose to the organs at risk, which may lead to fewer side effects for patients with lymphomas. Thus, we hypothesize that proton therapy may serve as a promising bridging strategy to CAR T-cell therapy for some patients.

Efficacy and safety-in analysis of short-course radiation followed by mFOLFOX-6 plus avelumab for locally advanced rectal adenocarcinoma

Background

Neoadjuvant chemotherapy and short-course radiotherapy followed by resection has been gaining recognition in the treatment of rectal cancer. Avelumab is a fully human immunoglobulin that binds Programmed Death-Ligand 1 (PD-L1) and prevents the suppression of the cytotoxic T cell immune response. This phase II trial evaluates the safety and pathologic response rate of short-course radiation followed by 6 cycles of mFOLFOX6 with avelumab in patients with locally advanced rectal cancer (LARC).

Methods

This study is prospective single-arm, multicenter phase II trial adopting Simon’s two-stage. Short-course radiation is given over 5 fractions to a total dose of 25 Gy. mFOLFOX6 plus avelumab (10 mg/kg) are given every 2 weeks for 6 cycles. Total mesorectal excision is performed 3–4 weeks after the last cycle of avelumab. Follow up after surgery is done every 3 months to a total of 36 months. Adverse event data collection is recorded at every visit.

Results

13 out of 44 patients with LARC were enrolled in the first stage of the study (30% from total sample size). All patients met the inclusion criteria and received the full short-course radiation course followed by 6 cycles of mFOLFOX6 plus avelumab. 12 out of the 13 patients completed TME while one patient had progression of disease and was dropped out of the study. The sample consisted of 9 (69%) males and 4 (31%) females with median age of 62 (33–73) years. The first interim analysis revealed that 3 (25%) patients achieved pathologic complete response (pCR) (tumor regression grade, TRG 0) out of 12. While 3 (25%) patients had near pCR with TRG 1. In total, 6 out of 12 patients (50%) had a major pathologic response. All patients were found to be MMR proficient. The protocol regimen was well tolerated with no serious adverse events of grade 4 reported.

Conclusion

In patients with LARC, neoadjuvant radiation followed by mFOLFOX6 with avelumab is safe with a promising pathologic response rate.

Trial Registration Number and Date of Registration ClinicalTrials.gov NCT03503630, April 20, 2018. https://clinicaltrials.gov/ct2/show/NCT03503630?term=NCT03503630&draw=2&rank=1.

Short-course radiation followed by mFOLFOX-6 plus avelumab for locally-advanced rectal adenocarcinoma

BACKGROUND

Current standard practice for locally advanced rectal cancer (LARC) entails a multidisciplinary approach that includes preoperative chemoradiotherapy, followed by total mesorectal excision, and then adjuvant chemotherapy. The latter has been accompanied by low compliance rates and no survival benefit in phase III randomized trials, so the strategy of administering neoadjuvant, rather than adjuvant, chemotherapy has been adapted by many trials, with improvement in pathologic complete response. Induction chemotherapy with oxaliplatin has been shown to have increased efficacy in rectal cancer, while short-course radiation therapy with consolidation chemotherapy increased short-term overall survival rate and decreased toxicity levels, making it cheaper and more convenient than long-course radiation therapy. This led to recognition of total neoadjuvant therapy as a valid treatment approach in many guidelines despite limited available survival data. With the upregulation (PDL-1) expression in rectal tumors after radiotherapy and the increased use of in malignant melanoma, the novel approach of combining immunotherapy with chemotherapy after radiation may have a role in further increasing pCR and improving overall outcomes in rectal cancer.

METHODS

The study is an open label single arm multi- center phase II trial. Forty-four recruited LARC patients will receive 5Gy x 5fractions of SCRT, followed by 6 cycles of mFOLFOX-6 plus avelumab, before TME is performed. The hypothesis is that the addition of avelumab to mFOLFOX-6, administered following SCRT, will improve pCR and overall outcomes. The primary outcome measure is the proportion of patients who achieve a pCR, defined as no viable tumor cells on the excised specimen. Secondary objectives are to evaluate 3-year progression-free survival, tumor response to treatment (tumor regression grades 0 & 1), density of tumor-infiltrating lymphocytes, correlation of baseline Immunoscore with pCR rates and changes in PD-L1 expression.

DISCUSSION

Recent studies show an increase in PD-L1 expression and density of CD8+ TILs after CRT in rectal cancer patients, implying a potential role for combinatory strategies using PD-L1- and programmed-death- 1 inhibiting drugs. We aim through this study to evaluate pCR following SCRT, followed by mFOLFOX-6 with avelumab, and then TME procedure in patients with LARC.

TRIAL REGISTRATION

Trial Registration Number and Date of Registration: ClinicalTrials.gov NCT03503630, April 20, 2018.

De-intensifying Radiation Therapy in HER-2 Positive Breast Cancer: To Boost or Not to Boost?

PURPOSE

Radiation therapy is fundamental in the management of breast cancer. After whole breast irradiation, an additional boost dose is often applied to the primary tumor bed. Here, we analyze the effect of radiation therapy boost on local control in patients with HER-2 positive breast cancer.

METHODS AND MATERIALS

We studied 1082 patients with HER-2 positive breast cancer who were originally enrolled in the Herceptin Adjuvant Trial and treated with breast-conserving surgery, radiation therapy, and adjuvant chemotherapy with trastuzumab. The primary endpoint of the study was to determine the effect of a radiation boost on local recurrence. Kaplan-Meier curves were generated, and hazard ratios were estimated using Cox regression.

RESULTS

Our analysis included 441 patients (40.8%) who received radiation therapy boost and 641 patients (59.2%) who did not, after completion of whole breast radiation. Patients from both groups had similar baseline characteristics in terms of age, nodal involvement, and grade. At a median follow-up of 11 years, local control was 93% (confidence interval, 90%-95%) in the radiation boost group compared with 91% (confidence interval, 89%-93%) in the no-boost group (P = .33). When analyzing patients by age, patients <40 years of age had a higher risk for local recurrence; however, this was not significantly lowered by the addition of boost. Furthermore, no local control benefit for boost was noted in both hormone receptor (HR) subtypes (HR+: P = .11; HR-: P = .98).

CONCLUSIONS

Patients with HER-2 positive breast cancer treated with breast-conserving surgery, whole breast radiation, and trastuzumab have excellent local control. Delivery of an additional radiation boost in this patient population was not shown to improve local control. Future studies are needed to identify subgroups of HER-2 positive patients who derive a clinically relevant benefit from radiation boost.

Modulation of radiation-induced damage of human glomerular endothelial cells by SMPDL3B

The intracellular molecular pathways involved in radiation-induced nephropathy are still poorly understood. Glomerular endothelial cells are key components of the structure and function of the glomerular filtration barrier but little is known about the mechanisms implicated in their injury and repair. The current study establishes the response of immortalized human glomerular endothelial cells (GEnC) to ionizing radiation (IR). We investigated the role of sphingolipids and the lipid-modifying enzyme sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) in radiation-induced GEnC damage. After delivering a single dose of radiation, long and very-long-chain ceramide species, and the expression levels of SMPDL3b were elevated. In contrast, levels of ceramide-1-phosphate (C1P) dropped in a time-dependent manner although mRNA and protein levels of ceramide kinase (CERK) remained stable. Treatment with C1P or knocking down SMPDL3b partially restored cell survival and conferred radioprotection. We also report a novel role for the NADPH oxidase enzymes (NOXs), namely NOX1, and NOX-derived reactive oxygen species (ROS) in radiation-induced GEnC damage. Subjecting cultured endothelial cells to radiation was associated with increased NOX activity and superoxide anion generation. Silencing NOX1 using NOX1-specific siRNA mitigated radiation-induced oxidative stress and cellular injury. In addition, we report a novel connection between NOX and SMPDL3b. Treatment with the NOX inhibitor, GKT, decreased radiation-induced cellular injury and restored SMPDL3b basal levels of expression. Our findings indicate the importance of SMPDL3b as a potential therapeutic target in radiation-induced kidney damage.

Post-mastectomy radiation therapy in breast cancer patients with 1-3 positive lymph nodes: No one size fits all

Post-mastectomy radiation therapy (PMRT) is standard therapy for advanced breast cancer. However, given the lower risk of recurrence, PMRT administration remains controversial in select patients with limited nodal disease. We performed a review of the literature that focuses on the effect of PMRT in breast cancer patients with 1-3 positive lymph nodes, mainly examining loco-regional recurrence (LRR) and overall survival (OS). Most studies, including a large meta-analysis by the EBCTCG, showed a significant improvement in LRR rates among patients receiving PMRT. While most studies demonstrated a trend towards OS improvement, only few studies showed a statistically significant OS or breast cancer-specific survival benefit for PMRT. As such, individualized treatment decisions are recommended, taking into consideration clinicopathological findings. Future studies with large sample sizes and long follow-up times are still needed to better assess the role of PMRT in patients with limited nodal involvement.

Craniocervical Rosai-Dorfman Disease Involving the Vertebral Artery: Case Report and Literature Review

BACKGROUND

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non-Langerhans cell reactive histiocytic disorder that rarely occurs in the central nervous system (CNS). Extranodal RDD most frequently involves the skin, upper respiratory tract, soft tissue, gastrointestinal tracts, bones, breast, and CNS.

CASE DESCRIPTION

RDD of the CNS infiltrates most commonly the dura of the sella, cavernous sinus, and the periclival regions. It is usually clinically and radiologically mistaken for meningioma because of its focal dural-based aspect. RDD is confirmed histologically by lymphoplasmacytic cells and histiocytes of varying size showing emperipolesis (lymphocytophagocytosis). To date, only 4 cases of RDD displaying spinal cord compression secondary to craniocervical junction involvement have been reported.

CONCLUSION

We report the case of a patient diagnosed with RDD localized at the foramen magnum extending to the base of the odontoid process and involving the V4 segment vertebral artery.

Noninvasive Cardioablation

Stereotactic body radiotherapy uses the principle of 3-dimensional localization of a target to deliver a high dose of radiation to a precise location. The aim of this technique is to ablate tissue noninvasively. Because of its high precision and target conformity, it can deliver a high dose of radiation to a specific area in a tissue without significantly affecting nearby tissues. It is being actively studied and even used in therapy for atrial fibrillation and ventricular tachycardia.

SMPDL3b modulates insulin receptor signaling in diabetic kidney disease

Sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) is a lipid raft enzyme that regulates plasma membrane (PM) fluidity. Here we report that SMPDL3b excess, as observed in podocytes in diabetic kidney disease (DKD), impairs insulin receptor isoform B-dependent pro-survival insulin signaling by interfering with insulin receptor isoforms binding to caveolin-1 in the PM. SMPDL3b excess affects the production of active sphingolipids resulting in decreased ceramide-1-phosphate (C1P) content as observed in human podocytes in vitro and in kidney cortexes of diabetic db/db mice in vivo. Podocyte-specific Smpdl3b deficiency in db/db mice is sufficient to restore kidney cortex C1P content and to protect from DKD. Exogenous administration of C1P restores IR signaling in vitro and prevents established DKD progression in vivo. Taken together, we identify SMPDL3b as a modulator of insulin signaling and demonstrate that supplementation with exogenous C1P may represent a lipid therapeutic strategy to treat diabetic complications such as DKD.

Assessing Radiosensitivity of Bladder Cancer in vitro: A 2D vs. 3D Approach

Background: Bladder cancer is the fourth most commonly diagnosed cancer among males worldwide. Current treatment strategies established for bladder cancer mainly consist of cystectomy yet advances in radiation therapy have pointed to the value of organ-preserving strategies in preserving patients' quality of life. Aim: To study and compare the radiosensitivity in two-dimension (2D) and physiologically-relevant three-dimension (3D) in vitro culture of three human bladder cancer cell lines, RT4, T24, and UM-UC-3. Materials and Methods: Clonogenic assay was performed to assess cells' radiosensitivity in 2D. Employing the 3D Matrigel™-based cultures to enrich for cancer stem cells (CSCs) allowed us to assess the survival of this subpopulation of cells via evaluating the number, i.e., sphere forming unit (SFU), and the sizes of cultured spheres, formed from cells exposed to different radiation doses compared to non-irradiated cells. Results: Irradiating cells with increasing radiation doses revealed highest survival rates with RT4 cells in 2D, followed by T24 and UM-UC-3. In 3D, however, UM-UC-3 cells were shown to be the most radio-resistant as evidenced by the number of spheres formed, yet they displayed the least efficient volume reduction/regression (VR), whilst the volume decreased significantly for both RT4 and T24 cells. Sphere VR and sphere ratio (SR) values were then plotted against each other demonstrating a linear correlation between volume and number with RT4 and UM-UC-3 cell lines, but not T24. Lastly, multiple regression model was employed to evaluate the possibility of obtaining a function combining both 3D parameters, SR and VR, with the surviving fraction (SF) in 2D, and showed a linear regression for T24 cells only, with a correlation coefficient of 0.97 for the combined parameters. Conclusion: We were able to radiobiologically characterize 3 human bladder cancer cell lines showing differential effects of radiation between 2D and 3D culture systems, paving the way for achieving better assessment of radiosensitivity of bladder cancer in vitro.

Predictors of Cardiac Sparing in Deep Inspiration Breath-Hold for Patients With Left Sided Breast Cancer

Purpose: The purpose of this study was to evaluate patient-related non-dosimetric predictors of cardiac sparing with the use of deep inspiration breath-hold (DIBH) in patients with left-sided breast cancer undergoing irradiation (RT).

Materials and Methods: We retrospectively reviewed charts and treatment plans of one-hundred and three patients with left-sided breast cancer. All patients had both free-breathing (FB) and DIBH (with body surface tracking) plans available. (MHD) and V4 (heart volume receiving at least 4 Gy) were extracted from dose volume histograms. Fisher's exact and Chi-square tests were used to identify predictors of reductions in MHD and V4 after DIBH.

Results: One-hundred and three patients were identified and most underwent mastectomy. MHD and V4 decreased significantly in DIBH plans (0.74 ± 0.25 Gy vs. 1.72 ± 0.98 Gy, p < 0.0001 for MHD; 4 ± 4.98 cc vs. 20.79 ± 18.2 cc, p < 0.0001 for V4). Body mass index (BMI), smoking and timing of CT simulation (spring/winter vs. summer/fall) were significant predictors of reduction in MHD whereas BMI, field size, chemotherapy, axillary dissection, and timing of CT simulation predicted reduction in V4. On multivariate analysis, BMI, and timing of CT simulation remained significant predictors of the heart-sparing effect of DIBH.

Conclusions: In the setting of limited resources, identifying patients who will benefit the most from DIBH is extremely important. Prior studies have identified multiple dosimetric predictors of cardiac sparing and hereby we identified new non-dosimetric factors such as BMI and timing of treatments.

Postmastectomy Radiation Therapy in Women with T1-T2 Tumors and 1 to 3 Positive Lymph Nodes: Analysis of the Breast International Group 02-98 Trial

PURPOSE

To analyze the impact of postmastectomy radiation therapy (PMRT) for patients with T1-T2 tumors and 1 to 3 positive lymph nodes enrolled on the Breast International Group (BIG) 02-98 trial.

METHODS AND MATERIALS

The BIG 02-98 trial randomized patients to receive adjuvant anthracycline with or without taxane chemotherapy. Delivery of PMRT was nonrandomized and performed according to institutional preferences. The present analysis was performed on participants with T1-T2 breast cancer and 1 to 3 positive lymph nodes who had undergone mastectomy and axillary nodal dissection. The primary objective of the present study was to examine the effect of PMRT on risk of locoregional recurrence (LRR), breast cancer-specific survival, and overall survival.

RESULTS

We identified 684 patients who met the inclusion criteria and were included in the analysis, of whom 337 (49%) had received PMRT. At 10 years, LRR risk was 2.5% in the PMRT group and 6.5% in the no-PMRT group (hazard ratio 0.29, 95% confidence interval 0.12-0.73; P = .005). Lower LRR after PMRT was noted for patients randomized to receive adjuvant chemotherapy with no taxane (10-year LRR: 3.4% vs 9.1%; P = .02). No significant differences in breast cancer-specific survival (84.3% vs 83.9%) or overall survival (81.7% vs 78.3%) were observed according to receipt of PMRT.

CONCLUSION

Our analysis of the BIG 02-98 trial shows excellent outcomes in women with T1-T2 tumors and 1 to 3 positive lymph nodes found in axillary dissection. Although PMRT improved LRR in this cohort, the number of events remained low at 10 years. In all groups, 10-year rates of LRR were relatively low compared with historical studies. As such, the use of PMRT in women with 1 to 3 positive nodes should be tailored to individual patient risks.

Translational Aspects of Sphingolipid Metabolism in Renal Disorders

Sphingolipids, long thought to be passive components of biological membranes with merely a structural role, have proved throughout the past decade to be major players in the pathogenesis of many human diseases. The study and characterization of several genetic disorders like Fabry’s and Tay Sachs, where sphingolipid metabolism is disrupted, leading to a systemic array of clinical symptoms, have indeed helped elucidate and appreciate the importance of sphingolipids and their metabolites as active signaling molecules. In addition to being involved in dynamic cellular processes like apoptosis, senescence and differentiation, sphingolipids are implicated in critical physiological functions such as immune responses and pathophysiological conditions like inflammation and insulin resistance. Interestingly, the kidneys are among the most sensitive organ systems to sphingolipid alterations, rendering these molecules and the enzymes involved in their metabolism, promising therapeutic targets for numerous nephropathic complications that stand behind podocyte injury and renal failure.

Optimizing tumor immune response through combination of radiation and immunotherapy

Radiation therapy and immunotherapy are two highly evolving modalities for the treatment of solid tumors. Immunotherapeutic drugs can either stimulate the immune system via immunogenic pathways or target co-inhibitory checkpoints. An augmented tumor cell recognition by host immune cells can be achieved post-irradiation, as irradiated tissues can release chemical signals which are sensed by the immune system resulting in its activation. Different strategies combining both treatment modalities were tested in order to achieve a better therapeutic response and longer tumor control. Both regimens act synergistically to one another with complimentary mechanisms. In this review, we explore the scientific basis behind such a combination, starting initially with a brief historical overview behind utilizing radiation and immunotherapies for solid tumors, followed by the different types of these two modalities, and the biological concept behind their synergistic effect. We also shed light on the common side effects and toxicities associated with radiation and immunotherapy. Finally, we discuss previous clinical trials tackling this multimodality combination and highlight future ongoing research.

Intraoperative Radiation Therapy: A Promising Treatment Modality in Head and Neck Cancer

Every year, almost 62,000 are diagnosed with a head and neck cancer (HNC) and 13,000 will succumb to their disease. In the primary setting, intraoperative radiation therapy (IORT) can be used as a boost in select patients in order to optimize local control. Addition of external beam radiation to limited volumes results in improved disease control over surgery and IORT alone. In the recurrent setting, IORT can improve outcomes from salvage surgery especially in patients previously treated with external beam radiation. The use of IORT remains limited to select institutions with various modalities being currently employed including orthovoltage, electrons, and high-dose rate brachytherapy. Practically, execution of IORT requires a coordinated effort and careful planning by a multidisciplinary team involving the head and neck surgeon, radiation oncologist, and physicist. The current review summarizes common uses, outcomes, toxicities, and technical aspects of IORT in HNC patients.

E6-Associated Protein Dependent Estrogen Receptor Regulation of Protein Kinase A Regulatory Subunit R2A Expression in Neuroblastoma

E6ap is a known transcriptional coregulator for estrogen receptor alpha (Er, Erα) in the presence of estrogen. Protein kinase A (PKA) contains two regulatory subunits derived from four genes. Recent evidence demonstrates that PKA regulates E6ap activity. Data generated in our lab indicated estrogen dependent regulation of Pkar2a levels. Our project sets to investigate a possible feedback mechanism constituting of Erα and E6ap transcriptional regulation of Pkar2a expression. Western blot evaluated protein regulation correlations with E2 in mouse neuroblastoma lines. Bioinformatics detected estrogen response element (ERE) sequences. quantitative polymerase chain reaction (qPCR) validated the western blot results. ERE oligonucleotides were synthesized. Reporter gene transcriptional activity was evaluated via Luciferase assay output. Electromobility shift assay (EMSA) assessed direct binding between Erα relevant sequences. Chromatin immunoprecipitation (ChIP) and Re-ChIP were conducted in quantifying protein complex recruitment levels. Pkar2a protein expression directly correlated with E2, and four putative ERE sequences were identified. Pkar2a mRNA expression reverted to baseline with either E2 or E6ap absent. In the presence of E2, ERE-1 and ERE-4 possessed Luciferase reporter gene transcriptional capabilities. ERE-1 portrayed band shifts, representing direct binding to Erα with E2 supplementation. With E2, ERE-1 significantly enhanced Erα and E6ap recruitment levels to the Pkar2a promoter. Pkar2a is directly regulated by Erα and E6ap in the presence of estrogen stimulus. This work indicates a feedback mechanism in the interplay between PKA and E6ap, which may prove crucial for the role of both proteins in cancers and neurogenetic diseases like Angelman syndrome.

Sphingomyelinase-like phosphodiesterase 3b mediates radiation-induced damage of renal podocytes

The molecular mechanisms responsible for the development of proteinuria and glomerulosclerosis in radiation nephropathy remain largely unknown. Podocytes are increasingly recognized as key players in the pathogenesis of proteinuria in primary and secondary glomerular disorders. The lipid-modulating enzyme sphingomyelin phosphodiesterase acid-like 3B (SMPDL3b) is a key determinant of podocyte injury and a known off target of the anti-CD20 antibody rituximab (RTX). The current study investigates the role of sphingolipids in radiation-induced podocytopathy. After a single dose of radiation (8 Gy), several ceramide species were significantly elevated. In particular, C16:00, C24:00, and C24:1 ceramides were the most abundant ceramide species detected. These changes were paralleled by a time-dependent drop in SMPDL3b protein, sphingosine, and sphingosine-1-phosphate levels. Interestingly, SMPDL3b-overexpressing podocytes had higher basal levels of sphingosine-1-phosphate and maintained basal ceramide levels after irradiation. Morphologically, irradiated podocytes demonstrated loss of filopodia and remodeling of cortical actin. Furthermore, the actin binding protein ezrin relocated from the plasma membrane to the cytosol as early as 2 h after radiation. In contrast, SMPDL3b overexpressing podocytes were protected from radiation-induced cytoskeletal remodeling. Treatment with RTX before radiation exposure partially protected podocytes from SMPDL3b loss, cytoskeletal remodeling, and caspase 3 cleavage. Our results demonstrate that radiation injury induces early cytoskeletal remodeling, down-regulation of SMPDL3b, and elevation of cellular ceramide levels. Overexpression of SMPDL3b and pretreatment with RTX confer a radioprotective effect in cultured podocytes. These findings indicate a potential role for SMPDL3b and RTX in radiation-induced podocytopathy.-Ahmad, A., Mitrofanova, A., Bielawski, J., Yang, Y., Marples, B., Fornoni, A., Zeidan, Y. H. Sphingomyelinase-like phosphodiesterase 3b mediates radiation-induced damage of renal podocytes.

Botulinum Toxin Confers Radioprotection in Murine Salivary Glands

PURPOSE

Xerostomia is a common radiation sequela, which has a negative impact on the quality of life of patients with head and neck cancer. Current treatment strategies offer only partial relief. Botulinum toxins (BTX) have been successfully used in treating a variety of radiation sequelae such as cystitis, proctitis, fibrosis, and facial pain. The purpose of this study was to evaluate the effect of BTX on radiation-induced salivary gland damage.

METHODS AND MATERIALS

We used a previously established model for murine salivary gland irradiation (IR). The submandibular glands (SMGs) of C5BL/6 mice (n=6/group) were injected with saline or BTX 72 hours before receiving 15 Gy of focal irradiation. Saliva flow was measured 3, 7, and 28 days after treatment. The SMGs were collected for immunohistochemistry, confocal microscopy, and Western blotting. A cytokine array consisting of 40 different mouse cytokines was used to evaluate cytokine profiles after radiation treatment.

RESULTS

Irradiated mice showed a 50% reduction in saliva flow after 3 days, whereas mice preinjected with BTX had 25% reduction in saliva flow (P<.05). Cell death detected by TUNEL staining was similar in SMG sections of both groups. However, neutrophil infiltrate, detected by myeloperoxidase staining, was 3-fold lower for the BTX treated mice. A cytokine array showed a 2-fold upregulation of LPS-induced chemokine (LIX/CXCL5) 3 days after IR. BTX pretreatment reduced LIX levels by 40%. At 4 weeks after IR, the saline (control) group showed a 40% reduction in basal SMG weight, compared with 20% in the BTX group. Histologically, BTX-pretreated glands showed relative preservation of acinar structures after radiation.

CONCLUSIONS

These data suggest that BTX pretreatment ameliorates radiation-induced saliva dysfunction. Moreover, we demonstrate a novel role for CXCL5 in the acute phase of salivary gland damage after radiation. These results carry important clinical implications for the treatment of xerostomia in patients with head and neck cancer.

Survival benefit for adjuvant radiation therapy in minor salivary gland cancers

OBJECTIVES

The goal of the current study is to investigate the role of adjuvant radiation therapy (adjuvant RT) in minor salivary gland tumors (mSGT) using an established national database.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to identify patients treated with or without adjuvant RT for mSGT from 1988 to 2008. Regression analyses were performed to identify factors associated with improved overall survival (OS).

RESULTS

Most tumors were located within the oral cavity (75%) followed by nasal cavity/paranasal sinuses (15%). Multivariate Cox analysis showed that adjuvant RT was associated with better OS compared to surgery alone. Using logistic regression analysis, we provide a novel web based tool for predicting survival impact of adjuvant RT in patients with mSGT.

CONCLUSIONS

Adjuvant RT is associated with improved survival in patients with mSGT and adverse clinicopathologic factors such as advanced T/N category, adenoid cystic histology, high grade, and nasopharynx location.

Intraoperative radiation therapy for advanced cervical metastasis: a single institution experience

BACKGROUND

The purpose of this study is to review our experience with the use of IORT for patients with advanced cervical metastasis.

METHODS

Between August 1982 and July 2007, 231 patients underwent neck dissections as part of initial therapy or as salvage treatment for advanced cervical node metastases resulting from head and neck malignancies. IORT was administered as a single fraction to a dose of 15 Gy or 20 Gy in most pts. The majority was treated with 5 MeV electrons (112 pts, 50.5%).

RESULTS

1, 3, and 5 years overall survival (OS) after surgery + IORT was 58%, 34%, and 26%, respectively. Recurrence-free survival (RFS) at 1, 3, and 5 years was 66%, 55%, and 49%, respectively. Disease recurrence was documented in 83 (42.8%) pts. The majority of recurrences were regional (38 pts), as compared to local recurrence in 20 pts and distant failures in 25 pts. There were no perioperative fatalities.

CONCLUSIONS

IORT results in effective local disease control at acceptable levels of toxicity. Our results support the initiation of a phase III trial comparing outcomes for patients with cervical metastasis treated with or without IORT.

Intraoperative radiotherapy for parotid cancer: a single-institution experience

PURPOSE

Our practice policy has been to provide intraoperative radiotherapy (IORT) at resection to patients with head-and-neck malignancies considered to be at high risk of recurrence. The purpose of the present study was to review our experience with the use of IORT for primary or recurrent cancer of the parotid gland.

METHODS AND MATERIALS

Between 1982 and 2007, 96 patients were treated with gross total resection and IORT for primary or recurrent cancer of the parotid gland. The median age was 62.9 years (range, 14.3-88.1). Of the 96 patients, 33 had previously undergone external beam radiotherapy as a component of definitive therapy. Also, 34 patients had positive margins after surgery, and 40 had perineural invasion. IORT was administered as a single fraction of 15 or 20 Gy with 4-6-MeV electrons. The median follow-up period was 5.6 years.

RESULTS

Only 1 patient experienced local recurrence, 19 developed regional recurrence, and 12 distant recurrence. The recurrence-free survival rate at 1, 3, and 5 years was 82.0%, 68.5%, and 65.2%, respectively. The 1-, 3-, and 5-year overall survival rate after surgery and IORT was 88.4%, 66.1%, and 56.2%, respectively. No perioperative fatalities occurred. Complications developed in 26 patients and included vascular complications in 7, trismus in 6, fistulas in 4, radiation osteonecrosis in 4, flap necrosis in 2, wound dehiscence in 2, and neuropathy in 1. Of these 26 patients, 12 had recurrent disease, and 8 had undergone external beam radiotherapy before IORT.

CONCLUSIONS

IORT results in effective local disease control at acceptable levels of toxicity and should be considered for patients with primary or recurrent cancer of the parotid gland.

The acid sphingomyelinase/ceramide pathway: biomedical significance and mechanisms of regulation

One of the most intriguing enzymes of sphingolipid biology is acid sphingomyelinase (ASMase). In a phospholipase C reaction, ASMase catalyzes the cleavage of the phosphocholine head group of sphingomyelin to generate ceramide. Cumulative efforts of various laboratories over the past 40 years have placed ASMase and its product ceramide at the forefront of lipid research. Activation of the ASMase/ceramide pathway is a shared response to an ever-growing list of receptor and non-receptor mediated forms of cellular stress including: death ligands (TNFalpha, TRAIL, Fas ligand), cytokines (IL-1, IFNgamma), radiation, pathogenic infections, cytotoxic agents and others. The strategic role of ASMase in lipid metabolism and cellular stress response has sparked interest in investigatig the molecular mechanisms underlying ASMase activation. In this article, we review the translational role of the ASMase/ceramide pathway and recent advances on its mechanisms of regulation.

Treatment of eccrine porocarcinoma with metastasis to the parotid gland using intensity-modulated radiation therapy: a case report

Introduction

Cutaneous eccrine porocarcinomas are uncommon malignant tumors of the sweat gland.

Case Presentation

A 76-year-old Caucasian man presented to our hospital with a left temporal mass. We describe a case of eccrine porocarcinoma with metastasis to the parotid gland with special emphasis on the role of surgical resection and adjuvant radiation therapy.

Conclusion

Besides surgical resection, little is known about the role of adjuvant therapy in managing eccrine porocarcinomas. Radiation therapy should be considered within a multidisciplinary approach in patients with primary or recurrent eccrine porocarcinomas.

Downregulation of neutral ceramidase by gemcitabine: Implications for cell cycle regulation

Gemcitabine (GMZ) is a chemotherapeutic agent with well established effects on cell growth arrest and apoptosis. In this study, we investigated the potential roles of bioactive sphingolipids in mediating the growth suppressing effects of GMZ on a polyoma middle T transformed murine endothelial cell line. After 12-hour GMZ (0.6 microM) treatment, cell growth was arrested at the G(0)/G(1) phase as detected by flow cytometric cell cycle analysis and MTT cell viability analysis, and this was accompanied by dephosphorylation of the retinoblastoma protein (Rb). Furthermore, GMZ treatment resulted in increased levels of specifically the very long chain ceramides as determined by mass spectrometry. Mechanistically, GMZ did not appear to affect the activities of many enzymes of ceramide metabolism; however, GMZ caused a selective reduction in the protein levels of neutral ceramidase (NCDase), as indicated by Western blot analysis, with a concomitant decrease in NCDase activity. The significance of NCDase loss on cell cycle regulation was investigated by specific knockdown of the enzyme using small interfering RNA (siRNA). Interestingly, NCDase siRNA transfection was sufficient to induce a cell cycle arrest at G(0)/G(1) and an increase in total ceramide levels, with significant elevation in very long chain ceramides (C(24:1) and C(24:0)). NCDase siRNA also induced Rb dephosphorylation. These data provide evidence for a novel mechanism of action for GMZ and highlight downregulation of NCDase as a critical step in GMZ-mediated ceramide elevation and cell cycle arrest.

Defective acid sphingomyelinase pathway with Pseudomonas aeruginosa infection in cystic fibrosis

Acid sphingomyelinase (ASMase) is a key enzyme in sphingolipid metabolism, which can be activated by various cellular stress mechanisms including bacterial pathogens. Activation of ASMase generates ceramide, which is important for innate immune response to eliminate infected pathogens. The current study reveals a defective ASMase pathway after Pseudomonas aeruginosa infection in both a cystic fibrosis (CF) bronchial epithelial cell line (IB3-1 cell) and in the lungs of CF transmembrane conductance regulator (CFTR) knockout (KO) mice as compared with S9 cells and wild-type C57BL/6 mice. ASMase activity and total ceramide levels significantly increased in S9 cells and C57BL/6 mice with P. aeruginosa infection, but not in IB3-1 cells and CFTR KO mice. The silencing of CFTR by CFTR RNAi in S9 cells significantly decreased ASMase activity after bacterial infection as compared with controls. This study also demonstrates that induction of ASMase is responsible for modulating the immune response to bacterial infection. Blocking ASMase activity with specific ASMase RNAi, an ASMase inhibitor, or an ASMase antibody in S9 cells significantly increased IL-8 levels with P. aeruginosa infection compared with controls. Reciprocally, adding exogenous bacterial sphingomyelinase to IB3-1 cells significantly decreased IL-8 levels compared with untreated cells. In addition, silencing of ASMase in S9 cells also significantly decreased bacterial internalization. Adding exogenous bacterial sphingomyelinase to IB3-1 cells reconstituted the cell death response to P. aeruginosa infection. This study demonstrates that the defective ASMase pathway in CF is a key contributor to the unabated IL-8 response with P. aeruginosa infection and to the compromised host response failing to eradicate bacteria.

Molecular targeting of acid ceramidase: implications to cancer therapy

Increasingly recognized as bioactive molecules, sphingolipids have been studied in a variety of disease models. The impact of sphingolipids on cancer research facilitated the entry of sphingolipid analogues and enzyme modulators into clinical trials. Owing to its ability to regulate two bioactive sphingolipids, ceramide and sphingosine-1-phosphate, acid ceramidase (AC) emerges as an attractive target for drug development within the sphingolipid metabolic pathway. Indeed, there is extensive evidence supporting a pivotal role for AC in lipid metabolism and cancer biology. In this article, we review the current knowledge of the biochemical properties of AC, its relevance to tumor promotion, and its molecular targeting approaches.

Anti-ceramidase LCL385 acutely reduces BCL-2 expression in the hippocampus but is not associated with an increase of learned helplessness in rats

Evidence from in situ studies supports the role of anti-apoptotic factors in the antidepressant responses of certain psychotropics. The availability of anti-ceramidase pro-apoptocic compound (LCL385) provides an opportunity to test in vivo the relation between hippocampal apopotosis and learned helplessness.

METHOD

40 Sprague-Dawley male rodents underwent an FST after a treatment with LCL385, desipramine (DMI), or placebo (SAL) over 3 days. Behavioral responses, including immobility, swimming and climbing were counted during the 6min test. Western blot labeling was used to detect anti-apoptosis in hippocampus.

RESULTS

DMI alone was associated with reduced immobility and increased climbing whereas LCL385 alone showed a decrease in Bcl-2/beta-actin ratio.

CONCLUSIONS

Direct modulation of Bcl-2 expression in the hippocampus is not associated with learned helplessness in stressed rats. Three-day administration of DMI and LCL385 show divergent effects on behavioral and anti-apoptotic measures.