Objective: Here we investigate the ability of low-intensity ultrasound (LIUS) applied to the spinal cord to modulate the transmission of motor signals. Methods: Male adult Sprague-Dawley rats (n = 10, 250–300 g, 15 weeks old) were used in this study. Anesthesia was initially induced with 2% isoflurane carried by oxygen at 4 L/min via a nose cone. Cranial, upper extremity, and lower extremity electrodes were placed. A thoracic laminectomy was performed to expose the spinal cord at the T11 and T12 vertebral levels. A LIUS transducer was coupled to the exposed spinal cord, and motor evoked potentials (MEPs) were acquired each minute for either 5- or 10-minutes of sonication. Following the sonication period, the ultrasound was turned off and post-sonication MEPs were acquired for an additional 5 minutes. Results: Hindlimb MEP amplitude significantly decreased during sonication in both the 5- (p < 0.001) and 10-min (p = 0.004) cohorts with a corresponding gradual recovery to baseline. Forelimb MEP amplitude did not demonstrate any statistically significant changes during sonication in either the 5- (p = 0.46) or 10-min (p = 0.80) trials. Conclusion: LIUS applied to the spinal cord suppresses MEP signals caudal to the site of sonication, with recovery of MEPs to baseline after sonication. Significance: LIUS can suppress motor signals in the spinal cord and may be useful in treating movement disorders driven by excessive excitation of spinal neurons.

For women with access to healthcare and early detection, breast cancer deaths are caused primarily by metastasis rather than growth of the primary tumor. Metastasis has been difficult to study because it happens deep in the body, occurs over years, and involves a small fraction of cells from the primary tumor. Furthermore, within-tumor heterogeneity relevant to metastasis can also lead to therapy failures and is obscured by studies of bulk tissue. Here we exploit heterogeneity to identify molecular mechanisms of metastasis. We use “organoids”, groups of hundreds of tumor cells taken from a patient and grown in the lab, to probe tumor heterogeneity, with potentially thousands of organoids generated from a single tumor. We show that organoids have the character of biological replicates: within-tumor and between-tumor variation are of similar magnitude. We develop new methods based on population genetics and variance components models to build between-tumor and within-tumor statistical tests, using organoids analogously to large sibships and vastly amplifying the test power. We show great efficiency for tests based on the organoids with the most extreme phenotypes and potential cost savings from pooled tests of the extreme tails, with organoids generated from hundreds of tumors having power predicted to be similar to bulk tests of hundreds of thousands of tumors. We apply these methods to an association test for molecular correlates of invasion, using a novel quantitative invasion phenotype calculated as the spectral power of the organoid boundary. These new approaches combine to show a strong association between invasion and protein expression of Keratin 14, a known biomarker for poor prognosis, with p = 2 × 10⁻⁴⁵ for within-tumor tests of individual organoids and p < 10⁻⁶ for pooled tests of extreme tails. Future studies using these methods could lead to discoveries of new classes of cancer targets and development of corresponding therapeutics. All data and methods are available under an open source license at https://github.com/baderzone/invasion_2019. For women with access to healthcare and early detection, breast cancer deaths are caused primarily by metastasis rather than growth of the primary tumor. Metastasis has been difficult to study because it happens deep in the body, occurs over years, and involves a small fraction of cells from the primary tumor. Furthermore, individual cells within a tumor can behave very differently, leading to failures of therapies. Here we exploit heterogeneity to develop new methods to identify molecular mechanisms of metastasis. We use “organoids”, groups of hundreds tumor cells taken from a patient and grown in the lab. Thousands of organoids can be generated from a single tumor sample to probe different regions and amplify the amount of information provided. Organoids provide information about metastasis because they vary in their ability to invade the growth medium. We introduce a new phenotype for invasion obtained by converting the boundary of an organoid into a frequency spectrum, then summing the power across all frequencies. We analyze this metastasis-related phenotype by adapting methods from population genetics that compare the most extreme siblings in a family. We analogously compare the most invasive vs. least invasive organoids from each tumor. Power calculations suggest that studies of 50–100 individuals, with 100-1000 organoids generated from each, could reveal DNA mutations and aberrant gene expression associated with invasion. We validate this approach by demonstrating strong statistical significance between invasion and protein expression of Keratin 14, a known biomarker for poor prognosis. Future studies using these methods could lead to discoveries of new classes of cancer targets and development of corresponding therapeutics.

Background: Local delivery after resection of high-grade glioma, particularly glioblastoma (GBM), aims to increase intratumoral drug exposure while limiting systemic toxicity. The only U.S. Food and Drug Administration (FDA)-approved implantable intracranial chemotherapy is the carmustine (1,3-bis[2-chloroethyl]-1-nitrosourea; BCNU)-impregnated polyanhydride wafer (Gliadel wafer), indicated for newly diagnosed high-grade glioma and recurrent GBM. More than two decades of clinical use and randomized data show that intracavitary chemotherapy is feasible and confers a modest survival benefit in carefully selected patients. Nevertheless, Gliadel wafer has not altered the overall poor prognosis of GBM because of biological resistance to nitrosoureas, constrained brain-parenchymal pharmacokinetics, and device-related adverse effects. Objective: The aim is to synthesize clinical and preclinical evidence defining the current limitations of Gliadel wafer and to outline strategies for next-generation local delivery systems, with emphasis on GBM within the broader high-grade glioma setting. Methods: A narrative review of randomized and observational clinical studies, pharmacokinetic studies, and preclinical investigations evaluating Gliadel wafer and potential next-generation local delivery systems in GBM and other high-grade gliomas was performed. Results: The literature delineates key limitations of Gliadel wafer: short diffusion distances and burst-weighted carmustine release, high tumor cell resistance to carmustine due to heterogeneity, and device-related side effects. Emerging approaches to address these limitations include (i) multidrug systems with synergistic effects against GBM cells; (ii) advanced biomaterials that enable controlled and sustained release; and (iii) targeted agents with minimal off-target effects. Testing newer generations of local drug-delivery systems in more predictive translational models, such as patient-derived organoids and spontaneous large-animal glioma models, is essential to maximize the translatability of preclinical studies to human studies. However, broader adoption of spontaneous large-animal glioma models is constrained by ethical oversight, animal-welfare considerations, cost, and limited availability compared with rodent platforms. Conclusions: Next-generation local drug-delivery systems should include multiple synergistic tumor-selective drugs that can be released in a controlled, sustained manner deep into the residual tumor. Preclinical testing of these systems should be conducted in clinically relevant animal models that are more translatable than those used in early Gliadel wafer studies.

OBJECTIVE: Piriform cortex (PC) is one of the critical structures in the epileptogenesis of mesial temporal lobe epilepsy (mTLE), but its role is poorly understood. The authors examined the utility of apparent diffusion coefficient (ADC; an MR-based marker of tissue pathology) of the PC as a predictor of seizure outcome in patients with mTLE undergoing MR-guided laser interstitial thermal therapy (MRgLITT). METHODS: A total of 33 patients diagnosed with mTLE who underwent MRgLITT at the authors’ institution were included in the study. The 6-month postoperative seizure outcomes were classified using the International League Against Epilepsy (ILAE) system as good (complete seizure freedom, ILAE class I) and poor (seizure present, ILAE classes II–VI). The PC and ablation volumes were manually segmented from both the preoperative and intraoperative MRI sequences, respectively. The mean ADC intensities of 1) preablation PC; 2) total ablation volume; 3) ablated portion of PC; and 4) postablation residual PC were calculated and compared between good and poor outcome groups. Additionally, the preoperative PC volumes and proportion of PC volume ablated were examined and compared between the subjects in the two outcome groups. RESULTS: The mean age at surgery was 36.5 ± 3.0 years, and the mean follow-up duration was 1.9 ± 0.2 years. Thirteen patients (39.4%) had a good outcome. The proportion of PC ablated was significantly associated with seizure outcome (10.16 vs 3.30, p < 0.05). After accounting for the variability in diffusion tensor imaging acquisition parameters, patients with good outcome had a significantly higher mean ADC of the preablation PC (0.3770 vs −0.0108, p < 0.05) and the postoperative residual PC (0.4197 vs 0.0309, p < 0.05) regions compared to those with poor outcomes. No significant differences in ADC of the ablated portion of PC were observed (0.2758 vs −0.4628, p = 0.12) after performing multivariate analysis. CONCLUSIONS: A higher proportion of PC ablated was associated with complete seizure freedom. Preoperative and postoperative residual ADC measures of PC were significantly higher in the good seizure outcome group in patients with mTLE who underwent MRgLITT, suggesting that ADC analysis can assist with postablation outcome prediction and patient stratification.

Background: Local delivery after glioblastoma (GBM) resection aims to raise intratumoral drug exposure while limiting systemic toxicity. The only FDA-approved implantable therapy for GBM is the carmustine (BCNU)–impregnated polyanhydride wafer (Gliadel wafer). More than two decades of clinical use and randomized data show that intracavitary chemotherapy is feasible and confers a modest survival benefit in carefully selected patients. Nevertheless, Gliadel wafer has not inherently altered GBM’s overall poor prognosis due to biological resistance to nitrosoureas, constrained brain parenchymal pharmacokinetics, and device‑related adverse effects. Objective: To synthesize in-human and preclinical evidence defining the current limitations of Gliadel wafer and to outline strategies for next‑generation local delivery systems for GBM. Methods: Narrative review of randomized and observational clinical studies, pharmacokinetic studies, and preclinical models, drug-investigating Gliadel wafer and potential next-generation local delivery systems in GBM. Results: The literature delineates key limitations of Gliadel wafer: short diffusion distances and burst‑weighted carmustine release, high tumor cell resistance to carmustine due to its heterogeneity, and device‑related side effects. Emerging approaches to address these limitations include (i) multidrugs with synergistic effects against GBM cells; (ii) advanced biomaterials that enable controlled and sustained release; and (iii) targeted agents with minimal off-target effects. Testing newer generations of local drug-delivery systems in more predictive translational models, such as patient‑derived organoids and spontaneous large‑animal glioma models, is essential to maximize the translatability of preclinical studies to human studies. Conclusions: Next‑generation local drug-delivery systems should include multiple synergistic tumor-selective drugs that can be released in a controlled, sustained manner deep into the residual tumor. Preclinical testing of these systems can be conducted in clinically relevant animal models that are more translatable than those used in early Gliadel wafer studies.