Proof of Concept for Open Flow Microperfusion for Intratumoural Drug Administration in Equine Cutaneous Neoplasia.

Intratumoural drug delivery can achieve high local therapeutic exposure while limiting systemic effects, but heterogeneous distribution may compromise treatment efficacy and precision. This proof-of-concept study investigated open flow microperfusion (OFM) as a novel platform for local delivery of tigilanol tiglate (TT), an intratumoural antineoplastic agent with immunomodulatory and vascular-disrupting effects. Four horses with histologically confirmed cutaneous neoplasia (three sarcoids and one squamous cell carcinoma) underwent OFM using TT concentrations of 0.01-0.04 mg/mL delivered at 9 µL/min for 7-24 h over one to three consecutive days. OFM systems were well tolerated and remained functional for up to three days. Localized vascular disruption, polymorphonuclear cell recruitment, oncosis and tissue sloughing developed in association with perfused regions, consistent with recognized TT-induced tissue responses. Two sarcoids exhibited biologic responses that did not result in complete local tumour ablation. Tumour ablation was achieved initially in one squamous cell carcinoma, although deep-seated disease subsequently progressed, while one sarcoid was ablated and remained tumour-free 497 days after treatment. These preliminary findings demonstrate that OFM allows precise, sustained intratumoural TT challenge, resulting in characteristic tissue responses supporting further investigation of this local delivery platform for tumour-targeted therapies.