3D-Printed Scaffolds for Local Chemotherapeutic Delivery in Resected Spine Metastases

Spinal metastases often occur secondary to breast, lung and prostate cancer and lead to instability, pain and poor quality of life. Standard care for spine metastases includes a multidisciplinary approach with surgery playing a major role in tumor resection, stabilization and decompression. Surgical resection with adjuvant is an effective treatment, yet it is often accompanied by tumor recurrence from residual disease. Furthermore, acrylic cements applied to defect sites provide stability, but they do not promote bone repair and can become destabilized during recurrence events. Developing new tools to stabilize defect sites, promote bone repair and locally deliver therapeutics may circumvent these limitations. We have previously developed mechanically competent 3D printed lactide/mineral scaffolds conducive to bone repair in vivo. We have also developed 3D printed nanoporous scaffolds conducive to both bone repair and chemotherapeutic delivery. Here, we set out to assess doxorubicin and cisplatin uptake and release rates and efficacy of drug delivery in 2D and custom physiological 3D cultures of two human cancer cell lines associated with metastases, MDA-MB-231 (human breast) and C42B (human prostate). Composite scaffolds had a compressive modulus close to trabecular bone, and could sustainably and effectively release doxorubicin and cisplatin as measured against both breast and prostate cell lines in 2D and 3D custom physiological metastases models. As a proof-of-concept, doxorubicin loaded composite scaffolds were implanted into rat caudal vertebrae following MDA-MB-231 xenograft resection. Following 6 weeks of implantation, no adverse events were noted and microCT analysis revealed boney integration of the construct. Taken together, these data indicate that our composite scaffolds may be an appropriate alternate therapy to stabilize bone defects, promote bone repair and effectively inhibit cancer recurrence post-tumor resection. Future work will test composite scaffolds using in vivo bone metastases models.