Abstract 1408: Diffuse optical spectroscopic imaging reveals regimen-dependent changes in breast tumors throughout neoadjuvant chemotherapy

Abstract

Diffuse Optical Spectroscopic Imaging (DOSI) is a non-invasive near-infrared imaging modality than can provide label-free functional and metabolic information about breast tumors, probing depths up to several centimeters. Previous work has shown that DOSI has prognostic value for pathological response at key timepoints during neoadjuvant (presurgical) chemotherapy (NAC), including baseline, 24 hours after the first infusion, week 1, and at the midpoint of therapy. To date there have been almost no reports on how specific NAC regimens affect the prognostic capability of DOSI. Here we present a large multi-center DOSI dataset consisting of 54 breast tumors and 313 unique measurements taken across three timepoints during NAC: Baseline, week 1, and midpoint of treatment. We will show for the first time that the manifestation of DOSI response parameters (oxyhemoglobin, de-oxyhemoglobin, water, and lipid) is highly dependent on the specific NAC regimen used. Subjects were treated with either a Maximum Tolerated Dose (MTD) regimen, in which a higher dose is administered less frequently, or a Metronomic (MET) regimen, in which a smaller dose is given more frequently. MTD regimen of cytotoxic agents has traditionally been the most effective method to treat breast cancer as it aims to kill the maximum amount of tumor cells before regrowth. MET administration of cytotoxic therapies has shown antiangiogenic properties aiming to limit toxic side effects and drug resistance, while potentially inducing tumor dormancy and immunomodulation. Subjects treated with MTD regimen and also responding to this treatment exhibited an oxyhemoglobin flare in the first day of NAC. In contrast, subjects treated with MET presented only small fluctuations in oxyhemoglobin throughout the first week of NAC. The oxyhemoglobin flare has been theorized to be induced by an inflammatory effect significant for cell death, which could be in response to specifically the MTD regimen and its higher dosing. This study indicates that the specific regimen must be considered when using DOSI for NAC monitoring. It also suggests DOSI may provide biological insight into the regimen-specific mechanisms of action. Citation Format: Anup Tank, Hannah Peterson, Vivian Pera, Syeda Tabassum, Naomi Ko, Anais Leproux, Bruce Tromberg, Darren Roblyer. Diffuse optical spectroscopic imaging reveals regimen-dependent changes in breast tumors throughout neoadjuvant chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1408.