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The WHO recommends molecular characterization of CNS tumors. (Louis et al., 2021, 2016). However, many patients at diagnosis and recurrence, do not have tissue accessible for genomics. Blood-based liquid biopsy tests, provide a non-invasive means to obtain genomic data. Liquid biopsy tests are widely adopted to avoid side effects related to invasive biopsies in other solid tumors. However, for primary brain tumors, most patients have cfDNA concentrations below the Limit-of-Detection (LOD) of the tests. The primary contributor to low yield is the blood-brain barrier (BBB) which prevents free passage of tumor analytes into the circulatory system. BBB opening mediated by Focused Ultrasound (FUS) oscillation of microbubbles (MB) has led to an increase of tumor-derived circulating biomarkers in pre-clinical models and in human GBM (Zhu et al 2018, Meng et al 2021). Cordance Medical is developing a non-invasive, portable FUS platform that can enable clinic-based BBB opening treatments. The Cordance device utilizes three transducer types, a Type 1 transducer for non-invasive BBB opening localization obtains Doppler images of the Circle-of-Willis through the temporal lobe. The Doppler images align to the existing MRI using CoW as the fiducial. An array of Type 2 transducers for BBB opening to generate sufficient acoustic pressure to safely oscillate MBs to open the BBB. Finally, Type 3 transducers for safety monitoring receive echo signals from the MBs. Signals are analyzed for harmonic content which enables safety monitoring. The primary endpoint, we will be examining the Cordance platform's ability to increase the concentration of circulating biomarkers following a safe BBB opening. We will recruit patients with recurrent GBM. Patients will receive a baseline blood draw, a BBB opening treatment with the Cordance device, followed by a blood draw after the treatment. Liquid biopsy tests to be examined include the MSK ACCESS test and tumor-informed ddPCR MRD test.

A major impediment to treatment of brain cancers is the inability to transport drugs across the blood-brain barrier (BBB). The development of an effective, targeted, and non-invasive method to penetrate the BBB to deliver cancer therapeutics is an unmet need in the treatment of brain cancers. Large molecular weight chemo- and immuno-therapies such as doxorubicin and others may be potentially effective against brain cancers if such drugs are sufficiently bioavailable in the brain. Focused ultrasound techniques can safely and transiently open the BBB but current techniques require invasive/intrusive or expensive and high-touch procedures and are not optimal for wide adoption. To address this unmet need, we are developing an innovative technique to non-intrusively, non-invasively and transiently open the BBB in a specified location within the brain using guided ultrasound (US). Our device consists of a proprietary US generator that is controlled by a highly portable system that has a small physical footprint, enabling the US generator and system to be placed in confined spaces such as chemotherapy infusion centers. The US generator is cap-shaped device that is placed on a patient’s head. It includes multiple sets of ultrasound transducers that are distributed within the cap according to the anatomy of the skull. With our proprietary technique, we calculate the position of the cap in relation to the internal anatomy in a real-time manner with a non-intrusive and a non-invasive manner. We have recently concluded an extensive study that resulted in algorithms that can accurately guide the US to various targets within the brain across a spectrum of patients. We also have completed a pilot preclinical study on a large animal demonstrating our ability to open the BBB non-invasively and deposit a drug proxy (gadolinium and Evans Blue). Citation Format: Bhaskar Ramamurthy, Mallika Keralapura, Jack Marshall, Dan Need, Ryan Dittamore, Santosh Kesari, Ekokobe Fonkem. Non-intrusive, non-invasive and patient friendly focused ultrasound device as a delivery vehicle for CNS tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 386.

Steelhead (Oncorhynchus mykiss) populations have declined dramatically in many parts of their range in North America, most critically in Southern California, where these anadromous trout are now classified as ‘Endangered’ under the United States Endangered Species Act. The widespread introduction of hatchery rainbow trout, the domesticated freshwater resident form of the species O. mykiss, is one factor threatening the long-term persistence of native steelhead and other trout populations. To identify where native fish of coastal steelhead lineage remained, we performed a population genetic analysis of microsatellite and SNP genotypes from O. mykiss populations at the extreme southern end of their range in Southern California, USA and Baja California, Mexico. In the northern part of this region, nearly all populations appeared to be primarily descendants of native coastal steelhead. However, in the southern, more urbanized part of this region, the majority of the sampled populations were derived primarily from hatchery trout, indicating either complete replacement of native fish or a strong signal of introgression overlaying native ancestry. Nevertheless, these genetically introgressed populations represent potentially critical genetic resources for the continued persistence of viable networks of O. mykiss populations, given the limited native ancestry uncovered in this region and the importance of genetic variation in adaptation. This study elucidates the geographic distribution of native trout populations in this region, and serves as a baseline for evaluating the impacts of hatchery trout on native O. mykiss populations and the success of steelhead conservation and recovery efforts.