Del Rivero J, et al. - Experts ran a phase 1 study to establish an RP2D (recommended phase 2 dose) for vandetanib plus bortezomib in combination, a regimen seen as a dual strategy for targeting REarranged during Transfection (RET) In medullary thyroid cancer (MTC). They gave patients with advanced solid tumors increasing doses of bortezomib or vandetanib to evaluate the safety and tolerability of daily oral vandetanib and intravenous (IV) bortezomib administered on days 1, 4, 8, and 11 of a 28-day cycle. They established the MTD of the combination as bortezomib, 1.3 mg/m² IV days 1, 4, 8, and 11 with vandetanib 300 mg by mouth daily.