 Category theory could be a promising framework for OSR in general and QFT in particular, because the main reservation against the radical but also seemingly incoherent idea of relations without relata may depend on the common set theoretic framework. Bain (2013) offers a category theoretic formulation of such a radical OSR, Lam and Wütrich (2015) a critique and Eva (2016) a defense.  See SEP entries on   structural realism   (4.2 on OSR and QFT) and on   category theory.    