Evaluation of a Refined Implantable Resonator for Deep-Tissue EPR Oximetry in the Clinic

Chen, Eric; Tse, Dan; Hou, Huagang; Schreiber, Wilson; Schaner, Philip E.; Kmiec, Maciej M.; Hebert, Kendra A.; Kuppusamy, Periannan; Swartz, Harold M.; Williams, Benjamin B.

doi:10.1007/s00723-021-01376-5

Cited by 5 publications

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“…The potential limitation of providing data from one site and not providing information on oxygen distribution in the entire tissue may be mitigated using multiple implants to assess heterogeneity of oxygen (57,62), or by combining EPR oximetry with volumetric methods of oxygen assessment (63)(64)(65). The operational frequency, approximately 1,150 MHz, of the current EPR scanner limits the use of the OxyChip to superficial tumors; however, this limitation can be overcome using implantable resonators containing OxyChip-like sensors (66,67) or low-frequency and pulse EPR methods (68)(69)(70)(71). Potential improvements in the future could also include the use of other clinical imaging modalities in addition to ultrasound, e.g., CT or PET, to improve both the precision of implantation and visualization of the implant in the tumor during treatment and pO 2 measurements (72).…”

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confidence: 99%

First-In-Human Study in Cancer Patients Establishing the Feasibility of Oxygen Measurements in Tumors Using Electron Paramagnetic Resonance With the OxyChip

et al. 2021

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ObjectiveThe overall objective of this clinical study was to validate an implantable oxygen sensor, called the ‘OxyChip’, as a clinically feasible technology that would allow individualized tumor-oxygen assessments in cancer patients prior to and during hypoxia-modification interventions such as hyperoxygen breathing.MethodsPatients with any solid tumor at ≤3-cm depth from the skin-surface scheduled to undergo surgical resection (with or without neoadjuvant therapy) were considered eligible for the study. The OxyChip was implanted in the tumor and subsequently removed during standard-of-care surgery. Partial pressure of oxygen (pO2) at the implant location was assessed using electron paramagnetic resonance (EPR) oximetry.ResultsTwenty-three cancer patients underwent OxyChip implantation in their tumors. Six patients received neoadjuvant therapy while the OxyChip was implanted. Median implant duration was 30 days (range 4–128 days). Forty-five successful oxygen measurements were made in 15 patients. Baseline pO2 values were variable with overall median 15.7 mmHg (range 0.6–73.1 mmHg); 33% of the values were below 10 mmHg. After hyperoxygenation, the overall median pO2 was 31.8 mmHg (range 1.5–144.6 mmHg). In 83% of the measurements, there was a statistically significant (p ≤ 0.05) response to hyperoxygenation.ConclusionsMeasurement of baseline pO2 and response to hyperoxygenation using EPR oximetry with the OxyChip is clinically feasible in a variety of tumor types. Tumor oxygen at baseline differed significantly among patients. Although most tumors responded to a hyperoxygenation intervention, some were non-responders. These data demonstrated the need for individualized assessment of tumor oxygenation in the context of planned hyperoxygenation interventions to optimize clinical outcomes.

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