Comparison of an Anti‐α v β 3 Integrin NIR Fluorescent Probe and Indocyanin Green for Precision Resection of Naturally Occurring Sarcomas in Dogs—A Randomized Blinded Case‐Controlled Pilot Study

The infiltrative growth of sarcomas represents a challenge for complete resection, as tumour borders are not easily detectable. Fluorescence guided surgery (FGS) allows improved visualization of tumour margins and could improve resection accuracy. Unfortunately, studies validating the impact of FGS are rare, and direct comparisons of different dyes are not available. Dogs ( n = 20) that were presented for sarcoma resection were prospectively enrolled and randomized to either receive indocyanine green (ICG, Group 1) or a targeted anti‐α v β 3 integrin probe (Group 2) prior to surgery. FGS was performed in both groups with the surgeon blinded to treatment. The false positive and false negative rates as well as tumour‐to‐background ratio (TBR) were calculated for each dye. Correlation of fluorescent area and histologically confirmed tumour extension was determined using the Dice Coefficient (DC). The clinical impact of FGS was determined by assessing the rate of rightfully adapted resections. False positive signal was detected in 9/10 dogs in group 1 and 3/10 dogs in group 2. Mean TBR at skin level was higher in group 2 (4.5 and 5.3) compared to group 1, and this difference reached significance in formalin‐fixed tissue (5.3 vs. 2.6, p = 0.016). Correlation of fluorescent signal and histologic tumour extent was strong for both dyes (DC group 1 = 0.64; group 2 = 0.78). Resection of additional neoplastic tissue based on FGS was more frequent in group 2 (3/10 dogs) compared to group 1 (1/10 dogs). The initial results of this study indicate that the targeted anti‐α v β 3 integrin probe is more tumour selective than ICG in dogs. This pilot as well as the subsequent follow up study are registered at animalstudyregistry.org https://doi.org/10.17590/asr.0000321 .