Associations between DISC assessment and performance in obstetrics and gynecology residents.

OBJECTIVE: To determine if the DISC (Dominance, Influence, Steadiness/Submission, and Conscientious/ Compliance) assessment correlates with obstetrics and gynecology resident performance. STUDY DESIGN: A total of 46 residents completed the DISC assessment. Residents were classified as "administrators" based on service to the program or as "concerning" if they were on remediation. Residents were categorized by negative comments by nurses or other residents and severe adverse event (SAE)/patient complaints. A quantitative assessment of compliance was used to assess residents. In-service examination scores and faculty evaluations of residents were analyzed. A p value of < 0.05 was taken as significant. RESULTS: Residents with SAE/patient complaints had higher Influence (p = 0.021) and lower Conscientious/Compliance scores (p = 0.029). Administrator-residents demonstrated a positive correlation with Dominance (r = 0.336, p = 0.042). In-service examination scores positively correlated with Dominance and negatively with Steadiness/Submission. There was a negative correlation between resident compliance scores (based on residency requirements) and Steadiness/Submission (r = -0.495, p = 0.043). CONCLUSION: Residents who are successful in executing administrative duties, provide safe patient care, or obtain high scores on examinations may have a DISC profile that is high in Dominance and Conscientious/Compliance but lower in Steadiness/Submission and Influence. Implementation of programs to promote emotional intelligence may allow for increased compassionate and safe patient care.

Saposin C coupled lipid nanovesicles enable cancer-selective optical and magnetic resonance imaging.

PURPOSE: Nanovesicles composed of the phospholipid dioleylphosphatidylserine (DOPS) and a fusogenic protein, saposin C (SapC), selectively target and induce apoptotic cell death in a variety of human cancer cells in vitro and in vivo. We tested whether such tumor-homing nanovesicles are capable of delivering fluorescent probes and magnetic resonance (MR) contrast agents to cancerous tissue to aid in earlier detection and improve visualization. PROCEDURES: SapC-DOPS nanovesicles labeled with either a far-red fluorescent probe (CellVue® Maroon, CVM) or conjugated with a dextran coated MR contrast agent, ultrasmall superparamagnetic iron oxide (USPIO), were systemically administrated into xenografts for tumor detection using optical and MR imaging systems. RESULTS: SapC-DOPS nanovesicles were effectively detected in vivo in tumor-bearing animals using both optical and MR imaging techniques, thereby demonstrating the cancer-selective properties of these nanovesicles. CONCLUSIONS: SapC-DOPS nanovesicles offer promise as a new and robust theranostic agent for broad cancer-selective detection, visualization, and potential therapy.

Molecular engineering and validation of an oncolytic herpes simplex virus type 1 transcriptionally targeted to midkine-positive tumors.

BACKGROUND: Expression profile analyses of midkine (MDK), a multifunctional protein important in development but repressed postnataly, indicate that it is highly expressed in approximately 80% of adult carcinomas and many childhood cancers including malignant peripheral nerve sheath tumors (MPNST). In the present study, we sought to leverage its selective expression to develop a novel oncolytic herpes simplex virus (oHSV) capable of targeting developmentally primitive cancers that express MDK. METHODS: We sought to increase the oncolytic efficacy of the virus by fusing the human MDK promoter to the HSV type 1 neurovirulence gene, gamma(1)34.5, whose protein product increases viral replication. RESULTS: Tissue-specific MDK promoter activity in human tumor cells and transgene biological activity was confirmed in human MPNST tumor cells. In vitro replication and cytotoxicity in human fibroblasts and MPNST cells by plaque and MTT assays showed that oHSV-MDK-34.5 increased replication and cytotoxicity compared to oHSV-MDK-Luc. By contrast, no significant difference in cytotoxicity was detected between these viruses in normal human fibroblasts. oHSV-MDK-34.5 impaired in vivo tumor growth and increased median survival of MPNST tumor-bearing nude mice. CONCLUSIONS: The transcriptional targeting of HSV lytic infection to MDK-expressing tumor cells is feasible. oHSV-MDK-34.5 shows enhanced anti-tumor effects both in vitro and in vivo. Further studies are warranted and may lead to its use in clinical trials.

Cancer-selective targeting and cytotoxicity by liposomal-coupled lysosomal saposin C protein.

PURPOSE: Saposin C is a multifunctional protein known to activate lysosomal enzymes and induce membrane fusion in an acidic environment. Excessive accumulation of lipid-coupled saposin C in lysosomes is cytotoxic. Because neoplasms generate an acidic microenvironment, caused by leakage of lysosomal enzymes and hypoxia, we hypothesized that saposin C may be an effective anticancer agent. We investigated the antitumor efficacy and systemic biodistribution of nanovesicles comprised of saposin C coupled with dioleoylphosphatidylserine in preclinical cancer models. EXPERIMENTAL DESIGN: Neuroblastoma, malignant peripheral nerve sheath tumor and, breast cancer cells were treated with saposin C-dioleoylphosphatidylserine nanovesicles and assessed for cell viability, ceramide elevation, caspase activation, and apoptosis. Fluorescently labeled saposin C-dioleoylphosphatidylserine was i.v. injected to determine in vivo tumor-targeting specificity. Antitumor activity and toxicity profile of saposin C-dioleoylphosphatidylserine were evaluated in xenograft models. RESULTS: Saposin C-dioleoylphosphatidylserine nanovesicles, with a mean diameter of approximately 190 nm, showed specific tumor-targeting activity shown through in vivo imaging. Following i.v. administration, saposin C-dioleoylphosphatidylserine nanovesicles preferentially accumulated in tumor vessels and cells in tumor-bearing mice. Saposin C-dioleoylphosphatidylserine induced apoptosis in multiple cancer cell types while sparing normal cells and tissues. The mechanism of saposin C-dioleoylphosphatidylserine induction of apoptosis was determined to be in part through elevation of intracellular ceramides, followed by caspase activation. In in vivo models, saposin C-dioleoylphosphatidylserine nanovesicles significantly inhibited growth of preclinical xenografts of neuroblastoma and malignant peripheral nerve sheath tumor. I.v. dosing of saposin C-dioleoylphosphatidylserine showed no toxic effects in nontumor tissues. CONCLUSIONS: Saposin C-dioleoylphosphatidylserine nanovesicles offer promise as a novel, nontoxic, cancer-targeted, antitumor agent for treating a broad range of cancers.

Targeting cancer-initiating cells with oncolytic viruses.

Recent studies in a variety of leukemias and solid tumors indicate that there is significant heterogeneity with respect to tumor-forming ability within a given population of tumor cells, suggesting that only a subpopulation of cells is responsible for tumorigenesis. These cells have been commonly referred to as cancer stem cells (CSCs) or cancer-initiating cells (CICs). CICs have been shown to be relatively resistant to conventional anticancer therapies and are thus thought to be responsible for disease relapse. As such, they represent a potentially critical therapeutic target. Oncolytic viruses are in clinical trials for cancer and kill cells through mechanisms different from conventional therapeutics. Because these viruses are not susceptible to the same pathways of drug or radiation resistance, it is important to learn whether CICs are susceptible to oncolytic virus infection. Here we review the available data regarding the ability of several different oncolytic virus types to target CICs for destruction.

Neuroblastoma cell lines contain pluripotent tumor initiating cells that are susceptible to a targeted oncolytic virus.

BACKGROUND: Although disease remission can frequently be achieved for patients with neuroblastoma, relapse is common. The cancer stem cell theory suggests that rare tumorigenic cells, resistant to conventional therapy, are responsible for relapse. If true for neuroblastoma, improved cure rates may only be achieved via identification and therapeutic targeting of the neuroblastoma tumor initiating cell. Based on cues from normal stem cells, evidence for tumor populating progenitor cells has been found in a variety of cancers. METHODOLOGY/PRINCIPAL FINDINGS: Four of eight human neuroblastoma cell lines formed tumorspheres in neural stem cell media, and all contained some cells that expressed neurogenic stem cell markers including CD133, ABCG2, and nestin. Three lines tested could be induced into multi-lineage differentiation. LA-N-5 spheres were further studied and showed a verapamil-sensitive side population, relative resistance to doxorubicin, and CD133+ cells showed increased sphere formation and tumorigenicity. Oncolytic viruses, engineered to be clinically safe by genetic mutation, are emerging as next generation anticancer therapeutics. Because oncolytic viruses circumvent typical drug-resistance mechanisms, they may represent an effective therapy for chemotherapy-resistant tumor initiating cells. A Nestin-targeted oncolytic herpes simplex virus efficiently replicated within and killed neuroblastoma tumor initiating cells preventing their ability to form tumors in athymic nude mice. CONCLUSIONS/SIGNIFICANCE: These results suggest that human neuroblastoma contains tumor initiating cells that may be effectively targeted by an oncolytic virus.

Effective in vivo targeting of the mammalian target of rapamycin pathway in malignant peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumors (MPNST) are chemoresistant sarcomas with poor 5-year survival that arise in patients with neurofibromatosis type 1 (NF1) or sporadically. We tested three drugs for single and combinatorial effects on collected MPNST cell lines and in MPNST xenografts. The mammalian target of rapamycin complex 1 inhibitor RAD001 (Everolimus) decreased growth 19% to 60% after 4 days of treatment in NF1 and sporadic-derived MPNST cell lines. Treatment of subcutaneous sporadic MPNST cell xenografts with RAD001 significantly, but transiently, delayed tumor growth, and decreased vessel permeability within xenografts. RAD001 combined with the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib caused additional inhibitory effects on growth and apoptosis in vitro, and a small but significant additional inhibitory effect on MPNST growth in vivo that were larger than the effects of RAD001 with doxorubicin. RAD001 plus erlotinib, in vitro and in vivo, reduced phosphorylation of AKT and total AKT levels, possibly accounting for their additive effect. The results support the consideration of RAD001 therapy in NF1 patient and sporadic MPNST. The preclinical tests described allow rapid screening strata for drugs that block MPNST growth, prior to tests in more complex models, and should be useful to identify drugs that synergize with RAD001.

Efficacy and safety of the oncolytic herpes simplex virus rRp450 alone and combined with cyclophosphamide.

Oncolytic herpes simplex virus (oHSV) mutants are under development as anticancer therapeutics. One such vector, rRp450, is ICP6-deleted and expresses a prodrug enzyme for cyclophosphamide (CPA) (rat CYP2B1). Little is known about rRp450's toxicity profile, especially in combination with CPA. We tested rRp450/CPA for antitumor efficacy in an aggressive human xenograft sarcoma model, measured virus production in primary cells, and tested rRp450/CPA for safety in immunocompetent mice. CPA enhanced the antitumor efficacy of rRp450. Relative to wild-type HSV-1, rRp450 replication was attenuated approximately 10,000-fold in human primary hepatocytes, differentiated primary foreskin keratinocytes, and primary Schwann cells. In vivo, intravenous and intracranial (IC) rRp450 injection at the strength of 10(8) plaque-forming units (pfu) alone or followed 24 hours later by intraperitoneal (IP) CPA was well tolerated and had no significant effect clinically on blood counts or chemistries. By contrast, intravenous KOS was found to be uniformly neurotoxic at 10(5) and fatal at 10(6) pfu, and IC virus was fatal in most mice at 10(4) pfu. Low levels of virus DNA were detected in some organs following intravenous and IC virus injection, but were not significantly altered by CPA. HSV replication was not detected in reactivation studies of isolated organs. Our findings suggest rRp450/CPA is safe and warrants further study as a potential combination in anticancer therapeutics.

Tissue inhibitor of metalloproteinase-3 via oncolytic herpesvirus inhibits tumor growth and vascular progenitors.

Malignant solid tumors remain a significant clinical challenge, necessitating innovative therapeutic approaches. Oncolytic viral therapy is a nonmutagenic, biological anticancer therapeutic shown to be effective against human cancer in early studies. Because matrix metalloproteinases (MMP) play important roles in the pathogenesis and progression of cancer, we sought to determine if "arming" an oncolytic herpes simplex virus (oHSV) with an MMP-antagonizing transgene would increase virus-mediated antitumor efficacy. We generated oHSVs that express human tissue inhibitor of metalloproteinases 3 (TIMP3) or firefly luciferase and designated them rQT3 and rQLuc, respectively. We evaluated the antitumor efficacy of these viruses against neuroblastoma and malignant peripheral nerve sheath tumor (MPNST) xenografts. Relative to rQLuc, rQT3-infected primary human MPNST and neuroblastoma cells exhibited equivalent virus replication but increased cytotoxicity and reduced MMP activity. In vivo, rQT3-treated tumors showed delayed tumor growth, increased peak levels of infectious virus, immature collagen extracellular matrix, and reduced tumor vascular density. Remarkably, rQT3 treatment reduced circulating endothelial progenitors, suggesting virus-mediated antivasculogenesis. We conclude that rQT3 enhanced antitumor efficacy through multiple mechanisms, including direct cytotoxicity, elevated virus titer, and reduced tumor neovascularization. These findings support the further development of combined TIMP-3 and oncolytic virotherapy for cancer.

Oncolytic HSV and erlotinib inhibit tumor growth and angiogenesis in a novel malignant peripheral nerve sheath tumor xenograft model.

Malignant peripheral nerve sheath tumors (MPNSTs), driven in part by hyperactive Ras and epidermal growth factor receptor (EGFR) signaling, are often incurable. Testing of therapeutics for MPNST has been hampered by lack of adequate xenograft models. We previously documented that human MPNST cells are permissive for lytic infection by oncolytic herpes simplex viruses (oHSV). Herein we developed and characterized a xenograft model of human MPNST and evaluated the antitumor effects of oHSV mutants (G207 and hrR3) and the EGFR inhibitor, erlotinib. Additive cytotoxicity of these agents was found in human MPNST cell lines, suggesting that EGFR signaling is not critical for virus replication. Mice bearing human MPNST tumors treated with G207 or hrR3 by intraperitoneal or intratumoral injection showed tumor-selective virus biodistribution, virus replication, and reduced tumor burden. oHSV injection demonstrated more dramatic antitumor activity than erlotinib. Combination therapies showed a trend toward an increased antiproliferative effect. Both oHSV and erlotinib were antiangiogenic as measured by proangiogenic gene expression, effect on endothelial cells and xenograft vessel density. Overall, oHSVs showed highly potent antitumor effects against MPNST xenografts, an effect not diminished by EGFR inhibition. Our data suggest that inclusion of MPNSTs in clinical trials of oHSV is warranted.

Malignant peripheral nerve sheath tumors with high and low Ras-GTP are permissive for oncolytic herpes simplex virus mutants.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) occur most frequently in patients with neurofibromatosis type 1 and are often fatal. Current therapy relies upon radical surgical resection, which often fails to completely remove the tumor. To address the need for novel treatment approaches for this disease, we sought to determine if human MPNST-derived cell lines are sensitive to oncolytic Herpes simplex virus (oHSV) infection. Activation of the Ras pathway and its inhibitory effects on protein kinase R (PKR) activation have been shown to dictate cellular permissivity to oHSV mutants. Because NF-1-associated MPNSTs possess inherent hyperactive Ras, we hypothesized these tumors would be ideal therapeutic targets for oHSVs. PROCEDURE: Human MPNST-derived cell lines were examined for sensitivity to oHSV-mediated gene transduction, virus replication, cytotoxicity, and apoptosis. These parameters were correlated with PKR activation following oHSV infection and compared with normal human Schwann cells (NHSCs) without hyperactive Ras. RESULTS: MPNST-derived cell lines were efficiently transduced, supported virus replication and were killed by the oncolytic HSV mutants, including sporadic MPNSTs without hyperactive Ras. In contrast to the highly sensitive MPNST cell lines, NHSCs did not support mutant virus replication. CONCLUSIONS: MPNSTs are susceptible to lysis by oncolytic HSV mutants, regardless of Ras status. Tumor-selective virus replication in MPNST cells appears to be mediated by both cellular expression of ribonucleotide reductase and prevention of eIF2alpha phosphorylation. Virus-induced cytotoxicity of MPNST cell lines was caused by both direct lysis and apoptosis. Our data suggest the use of oncolytic HSV mutants may represent a novel treatment approach for patients with MPNSTs.

Widespread intratumoral virus distribution with fractionated injection enables local control of large human rhabdomyosarcoma xenografts by oncolytic herpes simplex viruses.

Novel methods of local control for sarcomas are needed. We investigated the antitumor effect of two related herpes simplex virus (HSV) mutants, NV1020 and NV1066, on human rhabdomyosracoma cells and xenografts. Cell death correlated with virus replication and apoptosis in cultured cells and tumors. Complete regression was seen in all tumors <250 mm(3) following a single injection, yet only half of tumors >250 mm(3) showed a complete response. Fractionation of the virus dose into five injection sites did not increase transduction efficiency, transgene expression, or virus production, but did yield more widespread intratumoral distribution. Despite the same total dose of virus, improved control of large tumors was seen using fractionated injections as all large tumors (500-700 mm(3)) had durable, complete regression. Our data suggest that oncolytic HSVs may be useful for local control of bulky rhabdomyosarcoma tumors and that fractionated virus administration results in a more widespread virus infection and better tumor control. Therefore, strategies to maximize intratumoral virus distribution at initial delivery should be sought.

Oncolytic herpes simplex virus mutants are more efficacious than wild-type adenovirus Type 5 for the treatment of high-risk neuroblastomas in preclinical models.

BACKGROUND: High-risk neuroblastoma (Nb) is incurable using current treatment regimens in the majority of patients. Oncolytic virotherapy is a novel approach being tested for several types of adult cancers. OBJECTIVES: To compare the susceptibility of Nb tumor models to oncolytic adenovirus and HSV mutants and delineate the mechanisms of resistance or sensitivity. METHODS: Human Nb cell lines were used to determine susceptibility to adenovirus type 5 wild-type and HSV1 mutant (NV1066) infection, adenovirus receptor expression, support of NV1066 replication, and induction of apoptosis. Human xenograft tumors in immunodeficient mice were evaluated for histological effects and tumor response to intratumoral injection of an oncolytic HSV mutant. RESULTS: All eight Nb cell lines tested in culture were relatively resistant to infection with wild type and attenuated adenoviruses. Cells expressed the cocksackie-adenovirus attachment receptor (CAR) but had low or absent expression of the internalization receptors (alphavbeta3, alphavbeta5 integrins). In contrast, all cells were uniformly sensitive to infection with the attenuated HSV mutant, NV1066. Productive virus replication and induction of apoptosis were observed in HSV-infected cells. CHLA-20 and LAN-5 xenograft tumors injected with a single dose of NV1066 showed a significant antitumor response, and the animals had a prolonged survival post infection in comparison to the PBS-treated control group. HSV injected tumors showed extensive areas of necrosis and morphologic evidence of apoptosis. CONCLUSIONS: Nb tumor models are resistant to adenovirus mediated oncolysis but highly sensitive to HSV mediated oncolysis. Further studies of HSV virotherapy as a novel treatment for Nb are warranted.