One of the biggest barriers in treating solid tumours is the inability of the therapeutic vectors to propagate throughout the tumour mass due to the high density of the tumour and tumour stroma. The dense nature of many solid tumours can be attributed to a gel-like substance known as the extracellular matrix (ECM). This thick and compact structure acts as a physical barrier by shielding the malignant cells and reducing drug penetration and efficacy. One method to tackle the over-expression of ECM in solid tumours, is by using a relaxin-expressing adenovirus designed to degrade the ECM within the tumour, thereby increasing the anti-tumour efficacy of oncolytic viruses. In this presentation, we explore this problem by introducing a system of reaction-diffusion equations, including tumour cells and anti-tumour viruses. Mimicking the heterogeneous environment observed in a solid tumour, we aim to model the dynamics of ECM degradation and the subsequent effect on the malignant cells due to changes in drug penetration and diffusion.