Phase I trial of bortezomib and celecoxib in patients with advanced solid tumors

13051 Background: The ubiquitin-proteosome pathway plays an important role in cell cycle regulation, neoplastic growth, and metastasis. Nuclear factor-kB (NF-kB) is a key transcription factor in cancer, primarily regulated by proteosome-mediated degradation of the inhibitor protein I kappa B alpha-associated protein kinase (IkBa). Interruption of this degradative pathway, with the 26S proteosome inhibitor bortezomib, has displayed significant clinical anti-tumor activity, in multiple myeloma and lymphomas. The role of bortezomib in the treatment of advanced solid tumors, however, is unclear at present. Preclinical work in multiple myeloma cell lines has demonstrated synergy in cytotoxicity and growth inhibiton with the combination of bortezomib and the cyclooxygenase (COX)-2 inhibitors. We therefore hypothesized that the combination of the COX-2 inhibitor celecoxib and bortezomib is a potentially active combination in the treatment of advanced solid tumors. Towards this aim, we are conducting a phase I study to determine the maximum tolerated dose (MTD) and toxicity profile of bortezomib and celecoxib. Methods: Patients with advanced solid tumors and an ECOG PS of 0–2 received escalating doses of bortezomib (1.0–1.6 mg/m2), either weekly for 5 of 6 weeks or twice weekly for 2 of 3 weeks, and celecoxib (200–400 mg twice daily). Accrual was planned to a maximum of 6 cohorts, each with a minimum of 3 patients. Only those dose-limiting toxicities (DLTs) occurring during the first cycle were used to define the MTD. DLTs included any grade 4 hematologic toxicity related to therapy, or any grade 3 or 4 non-hematologic toxicity. Results: To date, 10 patients (median age of 63y) have been treated. Represented tumor types include stage IV: colorectal, pancreatic, bladder, leiomyosarcoma, head and neck squamous cell carcinoma, hepatocellular, and renal cell. A median number of 2 cycles were administered. Thus far, no DLTs have been observed. No cumulative toxicities have been noted. No objective tumor response has been observed, however, stable disease was maintained in one heavily pre-treated patient with metastatic papillary renal cell cancer for 5 months. Conclusions: The combination of bortezomib and celecoxib is safe and well tolerated, with no dose-limiting toxicities thus far. [Table: see text]