Abstract OT2-02-03: Magnetic nano-device for identification of the breast sentinel nodes – A novel method
Authors: Beitsch PD , Hunt KK , Bold RJ , Gittleman MA , Blair SL , Alvarado MD , Harmer QJ 
Published: May 2016

Breast sentinel node biopsy (SNB) is a well-established procedure that has supplanted traditional axillary dissection for most clinically node-negative breast cancer patients. Techniques to identify the draining lymph nodes include colored dyes and radioactive compounds. The Sentimag system uses a non-radioactive magnetic tracer and a handheld magnetic probe to identify sentinel nodes (SNs). The Sentimag Intraoperative Comparison (SentimagIC) study compares the magnetic technique with the standard combination of radioisotope and isosulfan blue dye.

Methods: SiennaXP is a nano device composed of coated iron oxide nanoparticles designed to optimize lymphatic uptake and SN retention. The Sentimag breast SNB technique involves injection of 2cc of SiennaXP fluid into Sappey's subareolar plexus followed by 5 minutes of breast massage and an additional 15 minutes of time to optimize drainage prior to beginning the procedure. The Sentimag hand held probe is then used to identify a magnetic 'hotspot' through the skin of the axilla. The usual transverse axillary incision is made and the magnetometer is used to identify the SNs. The SentimagIC study involves utilizing the Sentimag technique in combination with the 'standard' techniques of isosulfan blue dye and 99technetium sulfur colloid. All blue, radioactive and magnetic SNs are removed and identified as stained blue (from isosulfan blue dye) or black/brown (from SiennaXP) or not, and both radioactive and magnetic counts are taken ex vivo on each node. Currently there are 6 active sites with a total of 60 patients enrolled.

Trial design: This is a pivotal, prospective, open label, multicenter, paired comparison of the magnetic technique with the standard of care for lymph node localization in patients with breast cancer.

Primary endpoints: The lymph node detection rate with SentiMag / SiennaXP and the detection rate with the standard of care; and the safety of Sentimag / SiennaXP as indicated by adverse events.

Eligibility: Diagnosis of primary breast cancer or pure ductal carcinoma in situ (DCIS); Scheduled for sentinel lymph node biopsy; Clinical negative node status (i.e. T0-3, N0, M0).

Statistical methods: The primary hypothesis is that the magnetic technique is non-inferior to the standard technique. Based on an expected detection rate of 95% for both techniques and a non-inferiority margin of 5%, 140 subjects will be required to show non-inferiority with 85% power.

Discussion: SNB for breast cancer is a robust procedure, able to identify the draining lymph nodes of the breast in essentially all patients. Many techniques have been used including radioactive tracers (utilized on most cases) and colored dyes. SentiMag utilizes a unique nano device that can identify the same draining nodes but without the radioactivity used in most procedures. Radioactive dyes must be handled carefully to minimize radiation exposure to healthcare providers and the patient from the manufacturing process, delivery to facility, injection under a nuclear physician license, and the surgical procedure. This novel technique may supplant radioactive tracers allowing SNs to be removed without the patient/healthcare providers being exposed to radiation or the scheduling inconvenience of pre-procedure injection.

Citation Format: Beitsch PD, Hunt KK, Bold RJ, Gittleman MA, Blair SL, Alvarado MD, Harmer QJ. Magnetic nano-device for identification of the breast sentinel nodes – A novel method. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT2-02-03.