Lee Hwang

Local delivery of cancer-cell glycolytic inhibitors in high-grade glioma

BACKGROUND 3-bromopyruvate (3-BrPA) and dichloroacetate (DCA) are inhibitors of cancer-cell specific aerobic glycolysis. Their application in glioma is limited by 3-BrPAs inability to cross the blood-brain-barrier and DCAs dose-limiting toxicity. The safety and efficacy of intracranial delivery of these compounds were assessed. METHODS Cytotoxicity of 3-BrPA and DCA were analyzed in U87, 9L, and F98 glioma cell lines. 3-BrPA and DCA were incorporated into biodegradable pCPP:SA wafers, and the maximally tolerated dose was determined in F344 rats. Efficacies of the intracranial 3-BrPA wafer and DCA wafer were assessed in a rodent allograft model of high-grade glioma, both as a monotherapy and in combination with temozolomide (TMZ) and radiation therapy (XRT). RESULTS 3-BrPA and DCA were found to have similar IC50 values across the 3 glioma cell lines. 5% 3-BrPA wafer-treated animals had significantly increased survival compared with controls (P = .0027). The median survival of rats with the 50% DCA wafer increased significantly compared with both the oral DCA group (P = .050) and the controls (P = .02). Rats implanted on day 0 with a 5% 3-BrPA wafer in combination with TMZ had significantly increased survival over either therapy alone. No statistical difference in survival was noted when the wafers were added to the combination therapy of TMZ and XRT, but the 5% 3-BrPA wafer given on day 0 in combination with TMZ and XRT resulted in long-term survivorship of 30%. CONCLUSION Intracranial delivery of 3-BrPA and DCA polymer was safe and significantly increased survival in an animal model of glioma, a potential novel therapeutic approach. The combination of intracranial 3-BrPA and TMZ provided a synergistic effect.

Increased expression of glutamate transporter GLT-1 in peritumoral tissue associated with prolonged survival and decreases in tumor growth in a rat model of experimental malignant glioma

OBJECT Gliomas are known to release excessive amounts of glutamate, inducing glutamate excitotoxic cell death in the peritumoral region and allowing the tumor to grow and to expand. Glutamate transporter upregulation has been shown to be neuroprotective by removing extracellular glutamate in a number of preclinical animal models of neurodegenerative diseases, including amyotrophic lateral sclerosis and Parkinson disease as well as psychiatric disorders such as depression. The authors therefore hypothesized that the protective mechanism of glutamate transporter upregulation would be useful for the treatment of gliomas as well. METHODS In this study 9L gliosarcoma cells were treated with a glutamate transporter upregulating agent, thiamphenicol, an antibiotic approved in Europe, which has been shown previously to increase glutamate transporter expression and has recently been validated in a human Phase I biomarker trial for glutamate transporter upregulation. Cells were monitored in vitro for glutamate transporter levels and cell proliferation. In vivo, rats were injected intracranially with 9L cells and were treated with increasing doses of thiamphenicol. Animals were monitored for survival. In addition, postmortem brain tissue was analyzed for tumor size, glutamate transporter levels, and neuron count. RESULTS Thiamphenicol showed little effects on proliferation of 9L gliosarcoma cells in vitro and did not change glutamate transporter levels in these cells. However, when delivered locally in an experimental glioma model in rats, thiamphenicol dose dependently (10-5000 μM) significantly increased survival up to 7 days and concomitantly decreased tumor size from 46.2 mm(2) to 10.2 mm(2) when compared with lesions in nontreated controls. Furthermore, immunohistochemical and biochemical analysis of peritumoral tissue confirmed an 84% increase in levels of glutamate transporter protein and a 72% increase in the number of neuronal cells in the tissue adjacent to the tumor. CONCLUSIONS These results show that increasing glutamate transporter expression in peritumoral tissue is neuroprotective. It suggests that glutamate transporter upregulation for the treatment of gliomas should be further investigated and potentially be part of a combination therapy with standard chemotherapeutic agents.

Extravascular optical coherence tomography: evaluation of carotid atherosclerosis and pravastatin therapy.

Background and Purpose— Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy. Methods— An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E–deficient (ApoE−/−) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE−/− on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE−/− on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically exposed. Three-dimensional (3D; 2 spatial dimensions+time) and 4D (3 spatial dimensions+time) OCT images of the vessel lumen patency were evaluated. After perfusion, in situ OCT imaging was performed for statistical comparison with the in vivo results and final histology. Results— Intraoperative OCT imaging positively identified carotid plaque in 100% of ApoE−/− mice on HFD. ApoE−/− mice on HFD had a significantly decreased lumen patency when compared with that in wild-type mice (P<0.001). Pravastatin therapy was found to increase lumen patency significantly in ApoE−/− mice on HFD (P<0.01; compared with ApoE−/− on HFD). The findings were confirmed with OCT imaging after perfusion and histology. Conclusions— OCT imaging offers the potential for real-time, detailed vessel lumen evaluation, potentially improving surgical accuracy and outcomes during cerebrovascular neurosurgical procedures. Pravastatin significantly increases vessel lumen patency in the ApoE−/− mouse on HFD.

Improvement in the standard treatment for experimental glioma by fusing antibody Fc domain to endostatin

OBJECT Brain tumors pose many unique challenges to treatment. The authors hypothesized that Fc-endostatin may be beneficial. It is a newly synthesized recombinant human endostatin conjugated to the Fc domain of IgG with a long half-life (weeks) and unknown toxicity. The authors examined the efficacy of Fc-endostatin using various delivery methods. METHODS Efficacy was assessed using the intracranial 9L gliosarcoma rat model treated with Fc-endostatin for use in rodents (mFc-endostatin), which was administered either systemically or locally via different delivery methods. Oral temozolomide (TMZ) was administered in combination with mFc-endostatin to determine if there was a beneficial synergistic effect. RESULTS Intracranial delivery of mFc-endostatin via a polymer or convection-enhanced delivery 5 days after tumor implantation increased median survival, compared with the control group (p = 0.0048 and 0.003, respectively). Animals treated weekly with subcutaneous mFc-endostatin (started 5 days post-tumor implantation) also had statistically improved survival as compared with controls (p = 0.0008). However, there was no statistical difference in survival between the local and systemic delivery groups. Control animals had a median survival of 13 days. Animals treated either with subcutaneous mFc-endostatin weekly or with polymer had a median survival of 18 and 15 days, respectively, and those treated with oral TMZ for 5 days (Days 5-9) had a median survival of 21 days. Survival was further increased with a combination of oral TMZ and mFc-endostatin polymer, with a median survival of 28 days (p = 0.029, compared with TMZ alone). Subcutaneous mFc-endostatin administered every week starting 18 days before tumor implantation significantly increased median survival when compared with controls (p = 0.0007), with 12.5% of the animals ultimately becoming long-term survivors (that is, survival longer than 120 days). The addition of TMZ to either weekly or daily subcutaneous mFc-endostatin and its administration 18 days before tumor implantation significantly increased survival (p = 0.017 and 0.0001, respectively, compared with TMZ alone). Note that 12.5% of the animals treated with weekly subcutaneous mFc-endostatin and TMZ were long-term survivors. CONCLUSIONS Systemically or directly (local) delivered mFc-endostatin prolonged the survival of rats implanted with intracranial 9L gliosarcoma. This benefit was further enhanced when mFc-endostatin was combined with the oral chemotherapeutic agent TMZ.

Intracranial microcapsule chemotherapy delivery for the localized treatment of rodent metastatic breast adenocarcinoma in the brain

Significance Brain metastases represent the most common intracranial tumors in adults. Adequate chemotherapy delivery to the CNS is hindered by the blood–brain barrier. Efforts in intracranial chemotherapy delivery aim to maximize CNS levels while minimizing systemic toxicity; however, the success has been limited thus far. In this work, intracranial implanted doxorubicin and temozolomide microcapsules are compared with systemic administration in a novel rodent model of breast adenocarcinoma brain metastases. These microcapsules are versatile and efficacious, but that efficacy may depend on the ability of the chemotherapy to diffuse in brain tissue. These insights apply to other non-CNS applications of local drug delivery, and drugs should be evaluated based on their ability to penetrate the targeted tissue as well as their inherent efficacy. Metastases represent the most common brain tumors in adults. Surgical resection alone results in 45% recurrence and is usually accompanied by radiation and chemotherapy. Adequate chemotherapy delivery to the CNS is hindered by the blood–brain barrier. Efforts at delivering chemotherapy locally to gliomas have shown modest increases in survival, likely limited by the infiltrative nature of the tumor. Temozolomide (TMZ) is first-line treatment for gliomas and recurrent brain metastases. Doxorubicin (DOX) is used in treating many types of breast cancer, although its use is limited by severe cardiac toxicity. Intracranially implanted DOX and TMZ microcapsules are compared with systemic administration of the same treatments in a rodent model of breast adenocarcinoma brain metastases. Outcomes were animal survival, quantified drug exposure, and distribution of cleaved caspase 3. Intracranial delivery of TMZ and systemic DOX administration prolong survival more than intracranial DOX or systemic TMZ. Intracranial TMZ generates the more robust induction of apoptotic pathways. We postulate that these differences may be explained by distribution profiles of each drug when administered intracranially: TMZ displays a broader distribution profile than DOX. These microcapsule devices provide a safe, reliable vehicle for intracranial chemotherapy delivery and have the capacity to be efficacious and superior to systemic delivery of chemotherapy. Future work should include strategies to improve the distribution profile. These findings also have broader implications in localized drug delivery to all tissue, because the efficacy of a drug will always be limited by its ability to diffuse into surrounding tissue past its delivery source.

Correction: Intracranial microcapsule chemotherapy delivery for the localized treatment of rodent metastatic breast adenocarcinoma in the brain (Proceedings of the National Academy of Sciences of the United States of America (2014) 111, 45 (16071-16076) DOI: 10.1073/pnas.1313420110)

MEDICAL SCIENCES, ENGINEERING Correction for “Intracranial microcapsule chemotherapy delivery for the localized treatment of rodent metastatic breast adenocarcinoma in the brain,” by Urvashi M. Upadhyay, Betty Tyler, Yoda Patta, Robert Wicks, Kevin Spencer, Alexander Scott, Byron Masi, Lee Hwang, Rachel Grossman, Michael Cima, Henry Brem, and Robert Langer, which appeared in issue 45, November 11, 2014, of Proc Natl Acad Sci USA (111:16071–16076; first published October 27, 2014, 10.1073/pnas.1313420110). The authors note that, because Fig. 2 did not publish in color, the legend for Fig. 2 does not accurately describe the figure. The legend has been corrected to describe a black and white figure. The figure and its corrected legend appear below.

In-vivo and in-situ detection of atherosclerotic plaques using full-range complex-conjugate-free spectral domain optical coherence tomography in the murine carotid

Carotid endarterectomy is a common vascular surgical procedure which may help prevent patients’ risk of having a stroke. A high resolution real-time imaging technique that can detect the position and size of vascular plaques would provide great value to reduce the risk level and increase the surgical outcome. Optical coherence tomography (OCT), as a high resolution high speed noninvasive imaging technique, was evaluated in this study. Twenty-four 24-week old apolipoprotein E-deficient (ApoE-/-) mice were divided into three groups with 8 in each. One served as the control group fed with normal diet. One served as the study group fed with high-fat diet to induce atherosclerosis. The last served as the treatment group fed with both high-fat diet and medicine to treat atherosclerosis. Full-range, complex-conjugate-free spectral-domain OCT was used to image the mouse aorta near the neck area in-vivo with aorta exposed to the imaging head through surgical procedure. 2D and 3D images of the area of interest were presented real-time through graphics processing unit accelerated algorithm. In-situ imaging of all the mice after perfusion were performed again to validate the invivo detection result and to show potential capability of OCT if combined with surgical saline flush. Later all the imaged arteries were stained with H and E to perform histology analysis. Preliminary results confirmed the accuracy and fast imaging speed of OCT imaging technique in determining atherosclerosis.

Spinal Cord Ganglioglioma

Ganglioglioma of the spinal cord is a rare tumor that affects predominately the pediatric population. This type of intramedullary spinal cord neoplasm is generally considered benign, corresponding to WHO grade II. Common presenting symptoms include pain, neurologic deficits, and spinal deformity. Because of the indolent clinical course, risk of recurrence, and relative ineffectiveness of additional treatment modalities, early diagnosis with imaging as well as early surgical intervention are highly recommended. Complete, or near complete, resection usually results in long-term progression-free survival, and improvement of neurological status is achievable despite aggressive surgery. Improved microsurgical techniques, preoperative planning with MRI, and intraoperative neurophysiological monitoring have made a significant impact on the management of all spinal cord tumors including gangliogliomas.