Combined zoledronic acid and meloxicam reduced bone loss and tumour growth in an orthotopic mouse model of bone‐invasive oral squamous cell carcinoma

Abstract Oral squamous cell carcinoma ( OSCC ) is common in cats and humans and invades oral bone. We hypothesized that the cyclooxygenase ( COX )‐2 inhibitor, meloxicam, with the bisphosphonate, zoledronic acid ( ZOL ), would inhibit tumour growth, osteolysis and invasion in feline OSCC xenografts in mice. Human and feline OSCC cell lines expressed COX ‐1 and COX‐2 and the SCCF2 cells had increased COX ‐2 mRNA expression with bone conditioned medium. Luciferase‐expressing feline SCCF2Luc cells were injected beneath the perimaxillary gingiva and mice were treated with 0.1 mg kg −1 ZOL twice weekly, 0.3 mg kg −1 meloxicam daily, combined ZOL and meloxicam, or vehicle. ZOL inhibited osteoclastic bone resorption at the tumour–bone interface. Meloxicam was more effective than ZOL at reducing xenograft growth but did not affect osteoclastic bone resorption. Although a synergistic effect of combined ZOL and meloxicam was not observed, combination therapy was well‐tolerated and may be useful in the clinical management of bone‐invasive feline OSCC .