{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T09:05:16Z","timestamp":1785229516419,"version":"3.55.0"},"reference-count":45,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T00:00:00Z","timestamp":1785196800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MEDTEQ + consortium"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Background\/Objectives: Magnetotactic bacteria therapy is an emerging active intratumoral drug delivery platform in which drug-loaded, magnetically responsive bacteria are injected into a tumor and navigated through its microenvironment toward defined targets using an external magnetic field, fundamentally distinct from passive intratumoral injection. No endoscopic ultrasound (EUS)- or ultrasound (US)-guided delivery workflow for MTBT has been described, and five critical technical prerequisites for clinical translation remain unaddressed: three-body image registration, minimum contrast concentration for cone-beam computed tomography (CBCT) bolus localization, needle repositioning accuracy, optimal fiducial strategy, and EUS\/US procedural feasibility within the magnetic guidance apparatus. Methods: In three healthy female swine, we tested an image-guided intratumoral workflow at pancreatic and rectal sites. Gold rod fiducials were implanted under EUS in two animals and via transabdominal\/endorectal US in one animal. A needle was navigated toward the implanted fiducial group using real-time gold-fiducial shine-through, and 2 mL of saline mixed with iodine contrast (Isovue-370) at 15%, 10%, or 5% v\/v (one concentration per animal) was injected. Scan with CBCT was acquired before and after injection; fiducials, needle tip, and contrast bolus were segmented in 3D Slicer and their centroids compared to quantify targeting accuracy. Contrast visibility and artifact were scored by an expert radiologist on a five-point Likert scale. EUS feasibility within the magnetic apparatus was assessed using a full-scale cardboard replica of the CuraDrone PolarTrak. Results: Five percent v\/v Isovue-370 was the minimum concentration for reliable CBCT bolus identification (280\u2013360 HU; 1:1 injection-to-volume ratio). Needle repositioning accuracy was \u22642 cm in 5\/6 sites using fiducial shine-through guidance. Gold rod fiducials served a dual role: CBCT tumor registration and real-time EUS\/US navigation, not previously described for intratumoral injection. EUS was feasible within the PolarTrak with defined workflow adaptations. Conclusions: This pilot study demonstrates the technical feasibility of an EUS\/US\u2013CBCT workflow for MTBT, yielding quantitative, actionable parameters for first-in-human trial design. These feasibility findings, obtained in a small healthy animal cohort, are intended to inform the design of subsequent clinical studies.<\/jats:p>","DOI":"10.3390\/cancers18152427","type":"journal-article","created":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T08:52:01Z","timestamp":1785228721000},"page":"2427","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Preclinical Optimization of Magnetotactic Bacteria Therapy for the Treatment of Pancreatic and Rectal Cancer"],"prefix":"10.3390","volume":"18","author":[{"given":"Charles","family":"Tremblay","sequence":"first","affiliation":[{"name":"NanoRobotics Laboratory, Department of Computer and Software Engineering,  Institute of Biomedical Engineering, Polytechnique Montr\u00e9al, Montreal, QC H3T 1J4, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miriam Santos","family":"Dutra","sequence":"additional","affiliation":[{"name":"McGill Centre for Translational Research in Cancer, Lady Davis Institute for Medical Research, McGill University, Montreal, QC H3T 1E2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gilles","family":"Soulez","sequence":"additional","affiliation":[{"name":"Department of Radiology and Nuclear Medicine, Centre Hospitalier de l\u2019Universit\u00e9 de Montr\u00e9al (CHUM), Montreal, QC H2X 0C1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4234-9959","authenticated-orcid":false,"given":"Sylvain","family":"Martel","sequence":"additional","affiliation":[{"name":"NanoRobotics Laboratory, Department of Computer and Software Engineering,  Institute of Biomedical Engineering, Polytechnique Montr\u00e9al, Montreal, QC H3T 1J4, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5430-3750","authenticated-orcid":false,"given":"Gerald","family":"Batist","sequence":"additional","affiliation":[{"name":"McGill Centre for Translational Research in Cancer, Lady Davis Institute for Medical Research, McGill University, Montreal, QC H3T 1E2, Canada"},{"name":"Segal Cancer Centre, Jewish General Hospital, McGill University,   Montreal, QC H3T 1E2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2190-2583","authenticated-orcid":false,"given":"Corey S.","family":"Miller","sequence":"additional","affiliation":[{"name":"McGill Centre for Translational Research in Cancer, Lady Davis Institute for Medical Research, McGill University, Montreal, QC H3T 1E2, Canada"},{"name":"Division of Gastroenterology, Department of Medicine, Jewish General Hospital, McGill University, Montreal, QC H3T 1E2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1038\/nnano.2016.137","article-title":"Magneto-aerotactic bacteria deliver drug-containing nanoliposomes to tumour hypoxic regions","volume":"11","author":"Felfoul","year":"2016","journal-title":"Nat. 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