An intronic RNA element modulates Factor VIII exon-16 splicing

Pathogenic variants in the human Factor VIII (F8) gene cause Hemophilia A (HA). Here, we investigated the impact of 97 HA-causing single-nucleotide variants on the splicing of 11 exons from F8. For the majority of F8 exons, splicing was insensitive to the presence of HA-causing variants. However, splicing of several exons, including exon-16, was impacted by variants predicted to alter exonic splicing regulatory sequences. Using exon-16 as a model, we investigated the structure-function relationship of HA-causing variants on splicing. Intriguingly, RNA chemical probing analyses revealed a three-way junction structure at the 3'-end of intron-15 (TWJ-3-15) capable of sequestering the polypyrimidine tract. We discovered antisense oligonucleotides (ASOs) targeting TWJ-3-15 partially rescue splicing-deficient exon-16 variants by increasing accessibility of the polypyrimidine tract. The apical stem loop region of TWJ-3-15 also contains two hnRNPA1-dependent intronic splicing silencers (ISSs). ASOs blocking these ISSs also partially rescued splicing. When used in combination, ASOs targeting both the ISSs and the region sequestering the polypyrimidine tract, fully rescue pre-mRNA splicing of multiple HA-linked variants of exon-16. Together, our data reveal a putative RNA structure that sensitizes F8 exon-16 to aberrant splicing.

Trans-labial or introital ultrasounds for midurethral slings

Stress urinary incontinence is common in adult women. The use of introital or trans-labial ultrasound can help the surgeon (urologist or gynecologist) to better assess the type of incontinence the patient presents in order to guide him in the management of the patient. Often, surgical treatment with a mid-urethral sling (MSU) placement can be chosen in case of failure of non-invasive therapies (such as local estrogen or physical therapy) and if the clinical examination shows an urethral hypermobility. The use of ultrasound can help in this choice. Although rare, complications of MSU can sometimes cause disabling symptoms and be difficult to diagnose. Introital or trans-labial ltrasound can help diagnose them. The objective of this work was to describe the realization of ultrasound of stress urinary incontinence before or after the placement of a MSU, in order to make their realization easier for young surgeons which can use them in current practice.

Rescue of blood coagulation Factor VIII exon-16 mis-splicing by antisense oligonucleotides

The human Factor VIII ( F8 ) protein is essential for the blood coagulation cascade and specific F8 mutations cause the rare bleeding disorder Hemophilia A (HA). Here, we investigated the impact of HA-causing single-nucleotide mutations on F8 pre-mRNA splicing. We found that 14/97 (∼14.4%) coding sequence mutations tested in our study induced exon skipping. Splicing patterns of 4/11 (∼36.4%) F8 exons tested were especially sensitive to the presence of common disease-causing mutations. RNA-chemical probing analyses revealed a three-way junction structure at the 3' end of intron 15 (TWJ-3-15). TWJ-3-15 sequesters the polypyrimidine tract, a key determinant of 3' splice site strength. Using exon-16 of the F8 gene as a model, we designed specific antisense oligonucleotides (ASOs) that target TWJ-3-15 and identified three that promote the splicing of F8 exon-16. Interaction of TWJ-3-15 with ASOs increases accessibility of the polypyrimidine tract and inhibits the binding of hnRNPA1-dependent splicing silencing factors. Moreover, ASOs targeting TWJ-3-15 rescue diverse splicing-sensitive HA-causing mutations, most of which are distal to the 3' splice site being impacted. The TWJ-3-15 structure and its effect on mRNA splicing provide a model for HA etiology in patients harboring specific F8 mutations and provide a framework for precision RNA-based HA therapies.

Association of Autologous Tumor Lysate-Loaded Dendritic Cell Vaccination With Extension of Survival Among Patients With Newly Diagnosed and Recurrent Glioblastoma: A Phase 3 Prospective Externally Controlled Cohort Trial

Importance

Glioblastoma is the most lethal primary brain cancer. Clinical outcomes for glioblastoma remain poor, and new treatments are needed.

Objective

To investigate whether adding autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) to standard of care (SOC) extends survival among patients with glioblastoma.

Design, Setting, and Participants

This phase 3, prospective, externally controlled nonrandomized trial compared overall survival (OS) in patients with newly diagnosed glioblastoma (nGBM) and recurrent glioblastoma (rGBM) treated with DCVax-L plus SOC vs contemporaneous matched external control patients treated with SOC. This international, multicenter trial was conducted at 94 sites in 4 countries from August 2007 to November 2015. Data analysis was conducted from October 2020 to September 2021.

Interventions

The active treatment was DCVax-L plus SOC temozolomide. The nGBM external control patients received SOC temozolomide and placebo; the rGBM external controls received approved rGBM therapies.

Main Outcomes and Measures

The primary and secondary end points compared overall survival (OS) in nGBM and rGBM, respectively, with contemporaneous matched external control populations from the control groups of other formal randomized clinical trials.

Results

A total of 331 patients were enrolled in the trial, with 232 randomized to the DCVax-L group and 99 to the placebo group. Median OS (mOS) for the 232 patients with nGBM receiving DCVax-L was 19.3 (95% CI, 17.5-21.3) months from randomization (22.4 months from surgery) vs 16.5 (95% CI, 16.0-17.5) months from randomization in control patients (HR = 0.80; 98% CI, 0.00-0.94; P = .002). Survival at 48 months from randomization was 15.7% vs 9.9%, and at 60 months, it was 13.0% vs 5.7%. For 64 patients with rGBM receiving DCVax-L, mOS was 13.2 (95% CI, 9.7-16.8) months from relapse vs 7.8 (95% CI, 7.2-8.2) months among control patients (HR, 0.58; 98% CI, 0.00-0.76; P < .001). Survival at 24 and 30 months after recurrence was 20.7% vs 9.6% and 11.1% vs 5.1%, respectively. Survival was improved in patients with nGBM with methylated MGMT receiving DCVax-L compared with external control patients (HR, 0.74; 98% CI, 0.55-1.00; P = .03).

Conclusions and Relevance

In this study, adding DCVax-L to SOC resulted in clinically meaningful and statistically significant extension of survival for patients with both nGBM and rGBM compared with contemporaneous, matched external controls who received SOC alone.

Trial Registration

ClinicalTrials.gov Identifier: NCT00045968.

Long-Term Update of Stereotactic Radiosurgery for Benign Spinal Tumors

BACKGROUND

Stereotactic radiosurgery (SRS) for benign intracranial tumors is an established standard of care. The widespread implementation of SRS for benign spinal tumors has been limited by lack of long-term data.

OBJECTIVE

To update our institutional experience of safety and efficacy outcomes after SRS for benign spinal tumors.

METHODS

We performed a retrospective cohort study of 120 patients with 149 benign spinal tumors (39 meningiomas, 26 neurofibromas, and 84 schwannomas) treated with SRS between 1999 and 2016, with follow-up magnetic resonance imaging available for review. The primary endpoint was the cumulative incidence of local failure (LF), with death as a competing risk. Secondary endpoints included tumor shrinkage, symptom response, toxicity, and secondary malignancy.

RESULTS

Median follow-up was 49 mo (interquartile range: 25-103 mo, range: 3-216 mo), including 61 courses with >5 yr and 24 courses with >10 yr of follow-up. We observed 9 LF for a cumulative incidence of LF of 2%, 5%, and 12% at 3, 5, and 10 yr, respectively. Excluding 10 tumors that were previously irradiated or that arose within a previously irradiated field, the 3-, 5-, and 10-yr cumulative incidence rates of LF were 1%, 2%, and 8%, respectively. At last follow-up, 35% of all lesions had decreased in size. With a total of 776 patient-years of follow-up, no SRS-related secondary malignancies were observed.

CONCLUSION

Comparable to SRS for benign intracranial tumors, SRS provides longer term local control of benign spinal tumors and is a standard-of-care alternative to surgical resection.

Biplanar X-Ray Methods for Stereotactic Intraoperative Localization in Deep Brain Stimulation Surgery

BACKGROUND

Efficacy in deep brain stimulation (DBS) is dependent on precise positioning of electrodes within the brain. Intraoperative fluoroscopy, computed tomography (CT), or magnetic resonance imaging are used for stereotactic intraoperative localization (StIL), but the utility of biplanar X-ray has not been evaluated in detail.

OBJECTIVE

To determine if analysis of orthogonal biplanar X-rays using graphical analysis (GA), ray tracing (RT), and/or perspective projection (PP) can be utilized for StIL.

METHODS

A review of electrode tip positions comparing postoperative CT to X-ray methods was performed for DBS operations containing orthogonal biplanar X-ray with referential spheres and pins.

RESULTS

Euclidean (Re) errors for final DBS electrode position on intraoperative X-rays vs postoperative CT using GA, RT, and PP methods averaged 1.58 mm (±0.75), 0.74 mm (±0.45), and 1.07 mm (±0.64), respectively (n = 56). GA was more accurate with a ventriculogram. RT and PP predicted positions that correlated with third ventricular structures on ventriculogram cases. RT was the most stable but required knowledge of the geometric setup. PP was more flexible than RT but required well-distributed reference points. A single case using the O-arm demonstrated Re errors of 0.43 mm and 0.28 mm for RT and PP, respectively. In addition, these techniques could also be used to calculate directional electrode rotation.

CONCLUSION

GA, RT, and PP can be employed for precise StIL during DBS using orthogonal biplanar X-ray. These methods may be generalized to other stereotactic procedures or instances of biplanar imaging such as angiograms, radiosurgery, or injection therapeutics.

First results on survival from a large Phase 3 clinical trial of an autologous dendritic cell vaccine in newly diagnosed glioblastoma

Background

Standard therapy for glioblastoma includes surgery, radiotherapy, and temozolomide. This Phase 3 trial evaluates the addition of an autologous tumor lysate-pulsed dendritic cell vaccine (DCVax^®-L) to standard therapy for newly diagnosed glioblastoma.

Methods

After surgery and chemoradiotherapy, patients were randomized (2:1) to receive temozolomide plus DCVax-L (n = 232) or temozolomide and placebo (n = 99). Following recurrence, all patients were allowed to receive DCVax-L, without unblinding. The primary endpoint was progression free survival (PFS); the secondary endpoint was overall survival (OS).

Results

For the intent-to-treat (ITT) population (n = 331), median OS (mOS) was 23.1 months from surgery. Because of the cross-over trial design, nearly 90% of the ITT population received DCVax-L. For patients with methylated MGMT (n = 131), mOS was 34.7 months from surgery, with a 3-year survival of 46.4%. As of this analysis, 223 patients are ≥ 30 months past their surgery date; 67 of these (30.0%) have lived ≥ 30 months and have a Kaplan-Meier (KM)-derived mOS of 46.5 months. 182 patients are ≥ 36 months past surgery; 44 of these (24.2%) have lived ≥ 36 months and have a KM-derived mOS of 88.2 months. A population of extended survivors (n = 100) with mOS of 40.5 months, not explained by known prognostic factors, will be analyzed further. Only 2.1% of ITT patients (n = 7) had a grade 3 or 4 adverse event that was deemed at least possibly related to the vaccine. Overall adverse events with DCVax were comparable to standard therapy alone.

Conclusions

Addition of DCVax-L to standard therapy is feasible and safe in glioblastoma patients, and may extend survival.

Trial registration Funded by Northwest Biotherapeutics; Clinicaltrials.gov number: NCT00045968; https://clinicaltrials.gov/ct2/show/NCT00045968?term=NCT00045968&rank=1; initially registered 19 September 2002

Regression of experimental NIS-expressing breast cancer brain metastases in response to radioiodide/gemcitabine dual therapy

Treating breast cancer brain metastases (BCBMs) is challenging. Na⁺/I⁻ symporter (NIS) expression in BCBMs would permit their selective targeting with radioiodide (¹³¹I⁻). We show impressive enhancement of tumor response by combining¹³¹I⁻ with gemcitabine (GEM), a cytotoxic radiosensitizer. Nude mice mammary fat-pad (MFP) tumors and BCBMs were generated with braintropic MDA-MB-231Br cells transduced with bicistronically-linked NIS and firefly luciferase cDNAs. Response was monitored in vivo via bioluminescent imaging and NIS tumor expression.¹³¹I⁻/GEM therapy inhibited MFP tumor growth more effectively than either agent alone. BCBMs were treated with: high or low-dose GEM (58 or 14.5 mg/Kg×4); ¹³¹I⁻ (1mCi or 2×0.5 mCi 7 days apart); and ¹³¹I⁻/GEM therapy. By post-injection day (PID) 25, 82-86% of controls and 78-83% of ¹³¹I⁻-treated BCBM grew, whereas 17% low-dose and 36% high-dose GEM regressed. The latter tumors were smaller than the controls with comparable NIS expression (~20% of cells). High and low-dose ¹³¹I⁻/GEM combinations caused 89% and 57% tumor regression, respectively. High-dose GEM/¹³¹I⁻ delayed tumor growth: tumors increased 5-fold in size by PID45 (controls by PID18). Although fewer than 25% of cells expressed NIS, GEM/¹³¹I⁻ caused dramatic tumor regression in NIS-transduced BCBMs. This effect was synergistic, and supports the hypothesis that GEM radiosensitizes cells to ¹³¹I⁻.

Glomus tumors treated with stereotactic radiosurgery: A retrospective study

BACKGROUND

Glomus tumors are difficult to manage surgically because they are vascular tumors that are topographically associated with important vascular and neuronal structures. Hence, there is a strong risk of incomplete resection and a high morbidity rate. In addition, they grow slowly. Recent treatments have increasingly involved a combination of surgical resection and radiosurgery. We present our experience in treating glomus tumors of the skull base with stereotactic radiosurgery as an upfront therapy.

METHODS

We analyzed data from 13 consecutive patients with glomus tumors that were initially treated with stereotactic radiosurgery in our institute from February 2010 to April 2012. The tumor control rate, resolution of symptoms, and the complication rate were tabulated.

RESULTS

All patients were female with a median age of 63 (mean 62.7+/-14.6 years). The median treatment dose was 25.8 Gy (27.6 Gy +/- 9.5 Gy) and the median tumor volume 10.4 mL (9.2 +/- 6.5). The median follow-up was 47.4 months (51.8+/-11.2 months, range 31-74). The tumor control rate was 92.3%; 46.7% of the patients had noticeable tumor shrinkage. This happened at a median interval of 17 months (18.7+/-6.8) after treatment. Most patients with tinnitus had resolution of their symptoms (87.5%). Four patients presented with new symptoms and four patients with worsening of pre-existing symptoms. The time course of symptomatic improvement followed that of tumor size reduction. However, there was no statistical correlation between the amount of tumor reduction and symptomatic relief.

CONCLUSION

Stereotactic radiosurgery (SRS) is an effective upfront treatment option in the management of glomus tumors.

Continuous wireless pressure monitoring and mapping with ultra-small passive sensors for health monitoring and critical care

Continuous monitoring of internal physiological parameters is essential for critical care patients, but currently can only be practically achieved via tethered solutions. Here we report a wireless, real-time pressure monitoring system with passive, flexible, millimetre-scale sensors, scaled down to unprecedented dimensions of 1 × 1 × 0.1 cubic millimeters. This level of dimensional scaling is enabled by novel sensor design and detection schemes, which overcome the operating frequency limits of traditional strategies and exhibit insensitivity to lossy tissue environments. We demonstrate the use of this system to capture human pulse waveforms wirelessly in real time as well as to monitor in vivo intracranial pressure continuously in proof-of-concept mice studies using sensors down to 2.5 × 2.5 × 0.1 cubic millimeters. We further introduce printable wireless sensor arrays and show their use in real-time spatial pressure mapping. Looking forward, this technology has broader applications in continuous wireless monitoring of multiple physiological parameters for biomedical research and patient care.

Depleting tumor-specific Tregs at a single site eradicates disseminated tumors

Activation of TLR9 by direct injection of unmethylated CpG nucleotides into a tumor can induce a therapeutic immune response; however, Tregs eventually inhibit the antitumor immune response and thereby limit the power of cancer immunotherapies. In tumor-bearing mice, we found that Tregs within the tumor preferentially express the cell surface markers CTLA-4 and OX40. We show that intratumoral coinjection of anti-CTLA-4 and anti-OX40 together with CpG depleted tumor-infiltrating Tregs. This in situ immunomodulation, which was performed with low doses of antibodies in a single tumor, generated a systemic antitumor immune response that eradicated disseminated disease in mice. Further, this treatment modality was effective against established CNS lymphoma with leptomeningeal metastases, sites that are usually considered to be tumor cell sanctuaries in the context of conventional systemic therapy. These results demonstrate that antitumor immune effectors elicited by local immunomodulation can eradicate tumor cells at distant sites. We propose that, rather than using mAbs to target cancer cells systemically, mAbs could be used to target the tumor infiltrative immune cells locally, thereby eliciting a systemic immune response.

The temporal–spatial expression of VEGF, angiopoietins-1 and 2, and Tie-2 during tumor angiogenesis and their functional correlation with tumor neovascular architecture

Angiopoietins play a pivotal role in tumor angiogenesis by modulating vascular endothelial proliferation and survival. The expression of angiopoietins 1 and 2 (Ang-1 and Ang-2) and vascular endothelial growth factor (VEGF) has been documented in human malignant glioma. The expression of Ang-1, Ang-2, VEGF, and Tie-2, a member of the receptor tyrosine kinases and the natural receptor for both Ang-1 and Ang-2, follows a distinct transcriptional profile in vivo. Ang-2 and VEGF were expressed early in tumor formation and their levels increased throughout tumor growth. Their expression coincided with the expansion of the tumor mass and the formation of the vascular tree. There was no significant change in the expression of Tie-2 and Ang-1. The expression of Ang-1 and Tie-2 was more noticeable at the periphery of the tumor. The expression of Ang-2 was more robust at the periphery and within the tumor mass, and VEGF was more concentrated within the center of the tumor. This distinct expression profile may explain the morphology of the newly formed vessels at various times and regions of the tumor. The lack of concomitant expression of Ang-1 may underscore the unopposed endovascular induction by Ang-2 and VEGF resulting in the chaotic appearance and fragility of tumor vessels.

Abstract LB-139: In situ Treg immunomodulation at a single tumor site with CpG and immune checkpoint antibodies cures metastatic disease

Background: CD4+CD25+FOXP3+ regulatory T-cells (Tregs) infiltrate all tumor sites and play a central role in maintaining immune tolerance to cancers. Scientific question: Is the local immunomodulation of Tregs from a single tumor site sufficient to trigger a systemic anti-tumor immune response able to eradicate distant tumor sites ≤ Results: We found that tumor infiltrating Tregs preferentially express CTLA4 (CD152) and OX40 (CD134) compared to their counterparts in the blood and other lymphoid organs, both in mice and in human lymphomas. We show in a murine lymphoma model that OX40 and CTLA4 upregulation occurs specifically on Tregs directed against tumor antigens. Injections of low doses of anti-CTLA4 and anti-OX40 together with CpG, a TLR-9 agonist, directly into a single tumor site depletes the Tregs from the injected tumor but not from distant ones. This immunomodulation subsequently triggers an anti-tumor immune response able to cure mice with established disseminated disease. This triple combination is uniquely required as neither CpG alone nor mAbs without CpG are effective. Significance: immunomodulatory antibodies are currently under clinical development for cancer therapy. Their major toxicity is the triggering of auto-immune diseases. We show here that after injections of very little doses of these antibodies with CpG at one tumor site, their serum levels become undetectable. However, these doses are sufficient to trigger a systemic anti-tumor response able to eradicate distant sites. Impact: we recently have published positive results of intra-tumoral CpG in patients with follicular Lymphoma (Brody, Levy, et al. JCO, 2010). Anti-CTLA4 has just been approved by the FDA/EMEA in patients with metastatic melanoma. Anti-Ox40 antibodies are currently being tested in phase I/II clinical trials. Therefore, the combination described here can be tested in patients with injectable sites of lymphoma. Together, these results are in favor of a paradigm shift in cancer therapy where the immune system is targeted rather than the tumor itself.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-139. doi:1538-7445.AM2012-LB-139

Firefly luciferase-based dynamic bioluminescence imaging: a noninvasive technique to assess tumor angiogenesis

OBJECTIVE

Bioluminescence imaging (BLI) is emerging as a cost-effective, high-throughput, noninvasive, and sensitive imaging modality to monitor cell growth and trafficking. We describe the use of dynamic BLI as a noninvasive method of assessing vessel permeability during brain tumor growth.

METHODS

With the use of stereotactic technique, 10 firefly luciferase-transfected GL26 mouse glioblastoma multiforme cells were injected into the brains of C57BL/6 mice (n = 80). After intraperitoneal injection of D-luciferin (150 mg/kg), serial dynamic BLI was performed at 1-minute intervals (30 seconds exposure) every 2 to 3 days until death of the animals. The maximum intensity was used as an indirect measurement of tumor growth. The adjusted slope of initial intensity (I90/Im) was used as a proxy to monitor the flow rate of blood into the vascular tree. Using a modified Evans blue perfusion protocol, we calculated the relative permeability of the vascular tree at various time points.

RESULTS

Daily maximum intensity correlated strongly with tumor volume. At postinjection day 23, histology and BLI demonstrated an exponential growth of the tumor mass. Slopes were calculated to reflect the flow in the vessels feeding the tumor (adjusted slope = I90/Im). The increase in BLI intensity was correlated with a decrease in adjusted slope, reflecting a decrease in the rate of blood flow as tumor volume increased (y = 93.8e-0.49, R2 = 0.63). Examination of calculated slopes revealed a peak in permeability around postinjection day 20 (n = 42, P < .02 by 1-way analysis of variance) and showed a downward trend in relation to both postinjection day and maximum intensity observed; as angiogenesis progressed, tumor vessel caliber increased dramatically, resulting in sluggish but increased flow. This trend was correlated with Evans blue histology, revealing an increase in Evans blue dye uptake into the tumor, as slope calculated by BLI increases.

CONCLUSION

Dynamic BLI is a practical, noninvasive technique that can semiquantitatively monitor changes in vascular permeability and therefore facilitate the study of tumor angiogenesis in animal models of disease.

Abstract 477: Evaluation of tumor uptake and retention in a mouse model of breast cancer brain metastases by I-124 positron emission tomography (PET) imaging

The central nervous system (CNS) is emerging as the first site of metastatic disease in women with breast cancer. Women with hormone unresponsive tumors and/or HER-2 overexpressing tumors are disproportionately affected. Breast cancer brain metastasis represents a unique therapeutic challenge because of the limited access to the CNS of many anticancer drugs.

Radioiodide (131I) therapy may provide a therapeutic alternative since over 70% of invasive breast cancers, and some brain metastases express the sodium-iodide symporter (NIS). The rationale for this approach is based on the success of 131I radioablative therapy for thyroid cancers.

Objectives: To evaluate CNS permeability, kinetics of radioiodine uptake and retention in our NIS expressing breast cancer brain metastasis (BCBM) mouse model.

Methods: A brain-seeking clone of the hormone independent ((ER-/PR-/HER2-) human breast cancer cell line MDA-MB-231 (231BR) was transduced with a lentiviral vector carrying a bicistronic cassette with NIS and the firefly luciferase (Fluc) genes separated by an internal ribosomal entry site (IRES). Single cell clones were selected and characterized for iodide uptake and bioluminescence. 1 Million NIS-Fluc-MDAMB231 cells were implanted subcutaneously in the mammary fat pad (mfp) of nude mice (NCr nude) and tumor growth was monitored by serial in vivo bioluminescent imaging and external tumor volume measurements. NIS-Fluc mfp tumor xenografts were then explanted, 1×1 mm pieces excised and inserted stereotactically into the basal ganglia of the mouse. Bioluminescence imaging was used to follow intracranial tumor growth over time. Kinetics of 123I uptake and biodistribution in mfp xenografts mice was evaluated by ex vivo radioactive count and biodistribution of 124I was evaluated in vivo by positron emission tomography (PET) imaging on BCBM mice.

Results: Brain tumors 124I uptake was evident on the PET 1 hour post injection of the tracer, with values ranging from 1.60 to 3.25 % injected dose/gram of tissue (%ID/g) whereas thyroid uptake was between 6.99 and 11.19 %ID/g. At 20 hours post injection, the brain tumors showed a sustained 124I retention while uptake in most other organs (except thyroid and stomach) was close to background levels; brain tumor to normal brain tissue mean uptake ratio was ranging from to 217.12 to 541.50 (versus 2.02 to 2.68 at 1 hour post injection). The kinetics of 124I uptake was in agreement with the data obtained from the ex vivo counts in mfp xenografts.

Conclusions: We have characterized the kinetics of iodide uptake and retention in a model of breast cancer brain metastases. We showed that NIS expressing BCBM are able to concentrate and retain 124I for prolonged period of time. These results together with dosimetric calculations will allow us to adjust the dosage and timing for 131I therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 477.

The many roles of microRNAs in brain tumor biology

MicroRNAs (miRNAs) are now recognized as the primary RNAs involved in the purposeful silencing of the cell's own message. In addition to the established role of miRNAs as developmental regulators of normal cellular function, they have recently been shown to be important players in pathological states such as cancer. The authors review the literature on the role of miRNAs in the formation and propagation of gliomas and medulloblastomas, highlighting the potential of these molecules and their inhibitors as therapeutics.

HMG-CoA reductase inhibition causes increased necrosis and apoptosis in an in vivo mouse glioblastoma multiforme model

BACKGROUND

Statins are thought to have tumorolytic properties, reducing angiogenesis by inhibiting pro-angiogenic factors and inducing apoptosis of mural pericytes within the tumor vascular tree.

MATERIALS AND METHODS

An orthotopic mouse glioblastoma (GL-26) model was used to investigate the effect of simvastatin on glioblastoma vasculature in vivo. GL-26 cells were implanted into the striatum of C5LKa mice treated with either control, low- or high-dose simvastatin. Brains were analyzed for necrotic volume, apoptosis, morphology and pericytic cells within the vascular tree.

RESULTS

Low-dose simvastatin increased necrosis and apoptosis compared to both control and high-dose simvastatin groups. High-dose simvastatin increased vessel caliber by reducing pericytic cells along the tumor vessel wall compared to both control and low-dose simvastatin groups.

CONCLUSION

Simvastatin has a dual effect on tumorigenesis. At high doses, it may worsen instead of 'normalizing' tumor angio-architecture, albeit low doses affect tumor cell survival by promoting necrosis and apoptosis.

Buffered platelet-rich plasma enhances mesenchymal stem cell proliferation and chondrogenic differentiation

The success of tissue engineering applications can potentially be dramatically improved with the addition of adjuncts that increase the proliferation and differentiation of progenitor or stem cells. Platelet-rich plasma (PRP) has recently emerged as a potential biologic tool to treat acute and chronic tendon disorders. The regenerative potential of PRP is based on the release of growth factors that occurs with platelet rupture. Its autologous nature gives it a significant advantage in tissue engineering applications. To test whether PRP may be useful specifically for cartilage regeneration, a cell culture experiment was devised in which mesenchymal stem cells (MSCs) were grown in control media or media enhanced with inactivated, buffered PRP. Proliferation 7 days after PRP treatment was increased: 1.041 versus 0.199 for the control media cells ( p<0.001). The messenger RNA (mRNA) level of the osteogenic marker RUNX2 was 52.84 versus 26.88 for the control group ( p<0.005). Likewise the mRNA level of the chondrogenic markers Sox-9 and aggrecan was 29.74 versus 2.29 for the control group ( p<0.001) and 21.04 versus 1.93 ( p<0.001), respectively. These results confirm that PRP enhances MSC proliferation and suggest that PRP causes chondrogenic differentiation of MSC in vitro.

Development of a breast cancer brain metastases model to study 131I radioablative therapy

Abstract #2011

Background: An increasing number of women develop brain metastases (BM) after breast cancer (BC) treatment. A large proportion of these are estrogen/progesterone receptor-negative (ER-/PR-) and/or Her-2/neu overexpressing tumors. 131I radioablative therapy may provide a therapeutic alternative to treat metastases at this anatomic sanctuary since over 70% of invasive breast cancers, including a majority of ER- tumors and some brain metastases (unpublished data) express the sodium-iodide symporter (NIS). This approach relies on the success of radioiodide as a targeted treatment for thyroid cancers. To test this concept, we developed a BC BM model using tumor cells engineered to express NIS.&#x2028; Methods: MDAMB231 and SKBr3 cell lines were transduced with a lentiviral vector carrying a bicistronic cassette with NIS and the firefly luciferase (Fluc) genes separated by an internal ribosomal entry site. Single cell clones were selected and characterized for iodide uptake and bioluminescence. NIS-Fluc-MDAMB231 or NIS-Fluc SKBr3 cells (2.5 x 106 cells) were implanted subcutaneously (sc) in the mammary fat pad (mfp) of nude mice (NCr nude; 5-6 weeks old; n=5). NIS-Fluc mfp tumor xenografts were then explanted, 1x1 mm pieces excised and inserted stereotactically into the basal ganglia of the animal. All tumor development was monitored by serial in vivo bioluminescent imaging. Once established, brain tumors were excised, dissociated, established in tissue culture and re-implanted sc in the mfp of a new set of mice. Successive passages in the mfp then in the brain were performed in an attempt to increase tumor take. A second strategy tested with MDAMB231 cells consisted of direct implantation of cells into the basal ganglia. NIS expression was evaluated on tissue sections with a polyclonal antibody raised against the C-terminus of the human NIS.&#x2028; Results: All mice survived and were healthy in appearance. Intracranial implantation of mfp xenografts was highly successful with 66% take in both MDAMB231 (after two passages) and SKBr3 (after first passage). Bioluminescent imaging revealed sustained growth of tumors for more than 4 weeks. Microscopically, the explanted brain tumors had a cellular appearance without stromal cell or lymphocytic infiltration and were congruent with the histology of mfp xenografts. However, the tumor cell population was heterogeneous as NIS expression was present with plasma membrane staining in about 50% of SKBr3 and 15% of MDAMB231 cells. Direct cell implantations failed as no discernible bioluminescence was noted over a period of 3 weeks and no visible tumor at necropsy.&#x2028; Conclusions: A BCBM model has been developed by implanting intracranially mfp xenografts obtained with ER-/PR- +/- Her-2/neu overexpressing cells. Using this model, it will be possible to evaluate the effects of 131I on NIS-expressing BCBM.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2011.

Molecular events of brain metastasis

The brain is a privileged site of systemic cancer metastasis. The stages of the metastatic journey from the periphery to the brain are driven by molecular events that tie the original site of disease to the distant host tissue. This preference is not arbitrary but rather a directed phenomenon that includes such critical steps as angiogenesis and the preparation of the premetastatic niche. It appears that the connection between naive brain and cancer cells is made in advance of any metastatic breach of the blood-brain barrier. This contributes to the preferential homing of cancer cells to the brain. Delineation of the guidance mechanisms and elements that influence cancer cell motility and dormancy are important for the advancement of treatment modalities aimed at the remediation of this devastating disease.

Multimodality molecular imaging of glioblastoma growth inhibition with vasculature-targeting fusion toxin VEGF121/rGel

Vascular endothelial growth factor A (VEGF-A) and its receptors, Flt-1/FLT-1 (VEGFR-1) and Flk-1/KDR (VEGFR-2), are key regulators of tumor angiogenesis and tumor growth. The purpose of this study was to determine the antiangiogenic and antitumor efficacies of a vasculature-targeting fusion toxin (VEGF(121)/rGel) composed of the VEGF-A isoform VEGF(121) linked with a G(4)S tether to recombinant plant toxin gelonin (rGel) in an orthotopic glioblastoma mouse model by use of noninvasive in vivo bioluminescence imaging (BLI), MRI, and PET.

METHODS

Tumor-bearing mice were randomized into 2 groups and balanced according to BLI and MRI signals. PET with (64)Cu-1,4,7,10-tetraazacyclododedane-N,N',N'',N'''-tetraacetic acid (DOTA)-VEGF(121)/rGel was performed before VEGF(121)/rGel treatment. (18)F-Fluorothymidine ((18)F-FLT) scans were obtained before and after treatment to evaluate VEGF(121)/rGel therapeutic efficacy. In vivo results were confirmed with ex vivo histologic and immunohistochemical analyses.

RESULTS

Logarithmic transformation of peak BLI tumor signal intensity revealed a strong correlation with MRI tumor volume (r = 0.89, n = 14). PET with (64)Cu-DOTA-VEGF(121)/rGel before treatment revealed a tumor accumulation (mean +/- SD) of 11.8 +/- 2.3 percentage injected dose per gram at 18 h after injection, and the receptor specificity of the tumor accumulation was confirmed by successful blocking of the uptake in the presence of an excess amount of VEGF(121). PET with (18)F-FLT revealed significant a decrease in tumor proliferation in VEGF(121)/rGel-treated mice compared with control mice. Histologic analysis revealed specific tumor neovasculature damage after treatment with 4 doses of VEGF(121)/rGel; this damage was accompanied by a significant decrease in peak BLI tumor signal intensity.

CONCLUSION

The results of this study suggest that future clinical multimodality imaging and therapy with VEGF(121)/rGel may provide an effective means to prospectively identify patients who will benefit from VEGF(121)/rGel therapy and then stratify, personalize, and monitor treatment to obtain optimal survival outcomes.

In Vivo Near-Infrared Fluorescence Imaging of Integrin αvβ3 in an Orthotopic Glioblastoma Model

PURPOSE

Expression of cell adhesion molecule integrin alpha(v)beta(3) is significantly up-regulated during tumor growth, and sprouting of tumor vessels and correlates well with tumor aggressiveness. The purpose of this study was to visualize tumor integrin alpha(v)beta(3) expression in vivo by using near-infrared fluorescence (NIRF) imaging of Cy5.5-linked cyclic arginine-glycine-aspartic acid (RGD) peptide in an orthotopic brain tumor model.

PROCEDURES

U87MG glioma cells transfected with the firefly luciferase gene were stereotactically injected into nude mice in the right frontal lobe. Bioluminescence imaging (BLI) using D: -luciferin substrate and small animal magnetic resonance imaging (MRI) using gadolinium contrast enhancement were conducted weekly after tumor cell inoculation to monitor intracranial tumor growth. Integrin alpha(v)beta(3) expression was assessed by using a three-dimensional optical imaging system (IVIS 200) 0-24 hours after administration of 1.5 nmol monomeric Cy5.5-RGD via the tail vein. Animals were injected intravenously with both Texas Red-tomato lectin and Cy5.5-RGD prior to sacrifice to visualize peptide localization to tumor vasculature using histology.

RESULTS

Fluorescence microscopy demonstrated specific Cy5.5-RGD binding to both U87MG tumor vessels and tumor cells with no normal tissue binding. NIRF imaging showed highest tumor uptake and tumor to normal brain tissue ratio two hours postinjection (2.64 +/- 0.20). Tumor uptake of Cy5.5-RGD was effectively blocked by using unlabeled c(RGDyK), and injection of Cy5.5 dye alone showed nonspecific binding.

CONCLUSIONS

Optical imaging via BLI and NIRF offer a simple, effective, and rapid technique for noninvasive in vivo monitoring and semiquantitative analysis of intracranial tumor growth and integrin alpha(v)beta(3) expression. This study suggests that NIRF via fluorescently labeled RGD peptides may provide enhanced surveillance of tumor angiogenesis and anti-integrin treatment efficacy in orthotopic brain tumor models.

Incorporation of bone marrow-derived Flk-1-expressing CD34+ cells in the endothelium of tumor vessels in the mouse brain

OBJECTIVE

Neoangiogenesis is a prerequisite for the full phenotypic expression and growth of a malignant tumor mass. It is believed to be triggered by tissue hypoxia and involves proliferation and sprouting of the preexisting vessels and the recruitment of endothelial progenitor cells from bone marrow.

METHODS

A chimeric mouse model was used to examine the contribution of these progenitor cells to the neovasculature of brain tumor. T-cell knockout (RAG/KO5.2) mice were irradiated lethally, and their bone marrow was repopulated with T-cell depleted green fluorescent protein (GFP)-expressing bone marrow cells. RAG/RT-2 glioma cells were implanted into the striatum of the animals. Neovascular formation at various times of tumor growth was monitored together with the extent of incorporation of GFP+ bone marrow-derived cells within the vascular tree, in particular, cells carrying the endothelial progenitor markers CD34 and Flk-1.

RESULTS

The recruitment of GFP+ cells to the growing tumor and their incorporation into the vascular network occurred during the period of increasing vascular density and preceded the expansion of the tumor. The number of marrow-derived cells with endothelial morphology and phenotype was small but significant (4% of all endothelial cells at Day 12); 54% of all tumor vessels contained at least one GFP+ cell.

CONCLUSION

Our results suggest that bone marrow cells are recruited to newly formed and remodeled tumor vessels. Their recruitment may occur in response to signals from a highly proliferating milieu, and their role is to support the neovascular complex and to promote tumor growth.

Differential expression of angiopoietin-1 and angiopoietin-2 may enhance recruitment of bone-marrow-derived endothelial precursor cells into brain tumors

OBJECTIVES

Angiogenesis is necessary for sustained neoplastic development. The angiopoietins Ang-1 and Ang-2 have been implicated in the regulation of this process; recent reports have suggested that a net gain in Ang-2 activity may be an initiating factor for tumor angiogenesis. We examined the recruitment of bone marrow-derived endothelial precursor cells into developing tumor neovasculature, and the spatial relationship between these cells and angiopoietin (Ang-1 and Ang-2) expression.

METHODS

For this study T-cell depleted knockout mice (RAG-2/KO-5.2) were lethally irradiated and their bone marrow was reconstituted by bone marrow cells (BMCs) from transgenic mice (C57BL/Ka-Thy1.1) expressing green fluorescent protein (GFP). Rat glioma cells (RT-2/RAG) were then injected into the transplanted animals to form solid brain tumors. The animals were killed and their brains were analysed using immunohistochemistry and fluorescence-activated cell sorting.

RESULTS

We found that BMCs migrated preferentially into the tumor when compared to adjacent healthy brain parenchyma. Furthermore, GFP+/CD34+ cells represented up to 8% of endothelial-like cells within the walls of tumor blood vessels. In the tumor, significant colocalization of Ang-2 with GFP+/CD34+ cells was noted (>80%), but colocalization with Ang-1 never exceeded 20%. In normal tissue directly surrounding the tumor, GFP+/CD34+ cells colocalized strongly with both angiopoietins (>75% and >70% for Ang-1 and Ang-2, respectively).

DISCUSSION

The relative increase in angiopoietin-2 activity in brain tumors may result in the creation of a pro-angiogenic environment that enhances the recruitment of putative bone marrow-derived endothelial precursor cells into the tumor's developing vascular tree.

Hematopoietic stem cells give rise to perivascular endothelial-like cells during brain tumor angiogenesis

Bone marrow (BM) cells have recently been shown to give rise to skeletal, hepatic, cardiac, neural, and vascular endothelial tissues. However, it has been shown that this is the result of cell fusion rather than transdifferentiation of hematopoietic stem cells (HSC). For this study, we established a mouse model of brain tumor growth to investigate the differentiation potential of HSC into endothelial cells during brain tumor-induced angiogenesis. Nontransgenic (GFP(neg)) recipient mice were lethally irradiated, and their hematopoietic cells were subsequently repopulated by transplantation of a single green fluorescent protein (GFP)-expressing HSC. Rat glioma (RT-2/RAG) cells were then injected into the striatum of the chimeric mice 6-8 weeks post-transplantation. The animals were sacrificed 3-9 days after tumor implantation, and the mobilization, temporal-spatial distribution, and lineage-specific marker expression profile of the GFP(+) cells within the growing tumor were analyzed. We saw that GFP(+) cells gave rise to elongated, CD34(+)/Flk-1(+) cells that incorporated into the endothelium of tumor blood vessels. However, all GFP(+) cells were also CD45(+), and the presence of CD45 on the HSC-derived endothelial-like cells supports the hypothesis that the hematopoietic cells were recruited into the tumor milieu. The fact that we failed to demonstrate the expression of von Willebrand factor in these cells argues against a true endothelial identity. Nevertheless, the recruitment of HSC-derived endothelial-like cells was an extremely rare event in normal brain parenchyma, and, thus, the permissive influence afforded by the growing tumor appeared to enhance the perivascular tropism and acquisition of an endothelial phenotypes by a population of HSC-derived cells.

Identification of phenotypic neural stem cells in a pediatric astroblastoma

OBJECT

The goal of this study was to illustrate the findings of a significant subpopulation of cells within a pediatric astroblastoma that have the specific cell surface phenotype found on known human neural stem cells.

METHODS

Cells with a cell surface marker profile characteristic of human neural stem cells were isolated using fluorescence-activated cell sorting from a mostly nonmitotic astroblastoma removed from the brain of an 11-year-old girl. An unusually high proportion (24%) of the cells were CD133 positive and CD24, CD34, and CD45 negative (CD133(+)CD24(-)CD34(-)CD45(-) cells), the phenotypic antigenic pattern associated with neural stem cells; very few CD133-positive cells were not also CD24, CD34, and CD45 negative. Some cells (12%) were CD34 positive, indicating the presence within the tumor of hematopoietic stem cells. Cells formed cytospheres that resembled neurospheres when seeded into stem cell media and coexpressed beta-tubulin and glial fibrillary acidic protein (GFAP) but did not express the oligodendrocyte marker O4. Cell proliferation was demonstrated by incorporation of bromodeoxyuridine. The cells lost their capacity for self-renewal in vitro after four to six passages, although they continued to coexpress beta-tubulin and GFAP. The cells did not differentiate into neurons or astrocytes when placed in differentiation medium.

CONCLUSIONS

Although this astroblastoma contained a high proportion of phenotypic neural stemlike cells, the cells had limited proliferative capacity and multipotency. Their role in astroblastoma formation and growth is unknown.

Inverse design and fabrication tolerances of ultra-flattened dispersion holey fibers

We employ a Genetic Algorithm for the dispersion optimization of a range of holey fibers (HF) with a small number of air holes but good confinement loss. We demonstrate that a dispersion of 0 +/- 0.1 ps/nm/km in the wavelength range between 1.5 and 1.6 microm is achievable for HFs with a range of different transversal structures, and discuss some of the trade-offs in terms of dispersion slope, nonlinearity and confinement loss. We then analyze the sensitivity of the total dispersion to small variations from the optimal value of specific structural parameters, and estimate the fabrication accuracy required for the reliable fabrication of such fibers.

Incorporation of Naïve Bone Marrow Derived Cells into the Vascular Architecture of Brain Tumor

OBJECTIVE

Neovascularization is essential for tumor growth and invasion. Mounting evidence suggests that tumor cells recruit circulating endothelial progenitor cells to promote vasculogenesis to compliment tumor angiogenesis. This study examines the constitutive role of bone marrow-derived cells in this process.

METHODS

Rat glioma cells were implanted into brains of T-cell-depleted knockout mice. At various timepoints after tumor implantation, naïve bone marrow cells from ubiquitous transgenic mice expressing green fluorescent protein (GFP) were infused into these animals. The incorporation of GFP-positive cells into the vascular architecture was visualized by fluorescence confocal microscopy in conjunction with the transcription profiles of vascular endothelial growth factor (VEGF) and angiopoietin-1 and -2 (Ang-1 and Ang-2).

RESULTS

Of the cells infused, 8 days after tumor implantation, 0.49% were found exclusively sequestered in the vicinity of tumor vessels. This coincided with a decline in the expression of Ang-1 and a rise in the expression of VEGF and Ang-2. A few of these cells (0.66 of the 0.49%) localized onto the vascular wall. They resembled endothelial cells and expressed vWF.

CONCLUSION

The incorporation of bone marrow-derived unpurified endothelial cells into the tumor vascular bed is both time-limited and infrequent. These cells may play a supportive rather than a constitutive role in tumor neovascularization.

Effects of tumor suppressor gene (p53) on brain tumor angiogenesis and expression of angiogenic modulators

BACKGROUND

p53 retarded tumor growth by several known mechanisms, including suppression of cell proliferation and inhibition of tumor angiogenesis. Vascular endothelial growth factors (VEGF) and angiopoietins (Ang-1, Ang-2) are major angiogeneic modulators. The current study examined the effect of p53 on the expression of these factors in conjunction with tumor growth and vascular formation.

MATERIALS AND METHODS

Growth characteristics of rat glioma cells (RT-2) infected with retrovirus (MSCV) encoding a full-length human wild-type p53 gene were examined by clonogenic assay. Expression of the transgene in vitro was verified by RT-PCR and immunoprecipitation. Tumor morphology, vascular architecture and the expression of VEGF, Ang-1, Ang-2 and Tie-2 were examined by immunohistochemistry and semi-quantitative RT-PCR.

RESULTS

p53-infected cells showed retardation in growth and colony formation. In vivo, expression of the transgene resulted in prolonged survival and reduction of tumor volume (62%) and reduced the expression of VEGF (57.8%) and Tie-2 (15.4%) but not Ang-1 and Ang-2. The tumor exhibited increased necrosis (38%), hemorrhage and abnormal vascular architecture.

CONCLUSION

p53 causes tumor regression by suppressing tumor proliferation and indirectly induces involution of tumor vessels by fostering unopposed activity of Ang-2 in an environment of diminishing VEGF.

Suprasellar adrenocorticotropic hormone-secreting ectopic pituitary adenoma: case report and literature Review

OBJECTIVE AND IMPORTANCE

Functional ectopic pituitary adenomas are rare and can be misdiagnosed as extensions of pituitary adenomas when they are located in the vicinity of the normal gland. In this report, we present a case of an ectopic adrenocorticotropic hormone-secreting suprasellar pituitary adenoma that caused Cushing's disease. A literature review of previously reported ectopic pituitary adenomas is included to illustrate the diverse clinical manifestations of this disease entity.

CLINICAL PRESENTATION

An 11-year-old boy was noted to have hirsutism, a buffalo hump, and unexplained weight gain consistent with Cushing's syndrome. Laboratory investigations revealed that the boy had elevated adrenocorticotropic hormone and serum cortisol levels unsuppressed by dexamethasone. Magnetic resonance imaging scans were suggestive of a pituitary adenoma with suprasellar extension.

INTERVENTION

The initial transsphenoidal approach failed to achieve complete surgical resection. A repeat operation in which the pterional approach was used revealed a suprasellar pituitary adenoma without association with intrasellar contents. The patient's cushingoid symptoms improved significantly 3 months after surgery.

CONCLUSION

Ectopic pituitary adenomas should be considered in the differential diagnosis for all patients with Cushing's syndrome. Furthermore, surgical approaches should be chosen carefully once the diagnosis of ectopic pituitary adenoma is made.

Comparisons of tumor suppressor p53, p21, and p16 gene therapy effects on glioblastoma tumorigenicity in situ

The mutation and/or deletion of tumor suppressor genes have been postulated to play a major role in the genesis and the progression of gliomas. In this study, the functional expression and efficacy in tumor suppression of 3 tumor suppressor genes (p53, p21, and p16) were tested and compared in a rat GBM cell line (RT-2) after retrovirus mediated gene delivery in vitro and in vivo. Significant reductions in tumor cell growth rate were found in p16 and p21 infected cells (60 +/- 12% vs 66 +/- 15%) compared to p53 (35 +/- 9%). In vitro colony formation assay also showed significant reductions after p16 and p21 gene delivery (98 +/- 5% vs 91 +/- 10%) compared to p53 (50 +/- 18%). In addition, the tumor suppression efficacy were investigated and compared in vivo. Retroviral mediated p16 and p21 gene deliveries in glioblastomas resulted in more than 90% reductions in tumor growth (92 +/- 26% vs 90 +/- 22%) compared to p53 (62 +/- 18%). Tumor suppressor gene insertions in situ further prolonged animal survival. Overall p16 and p21 genes showed more powerful tumor suppressor effects than p53. The results were not surprising, as p16 and p21 are more downstream in the cell cycle regulatory pathway compared to p53. Moreover, the mechanism involved in each of their suppressor effects is different. This study demonstrates the feasibility of using tumor suppressor genes in regulating the growth of glioma in vitro and in situ.