This study is a single-arm, open-label, phase 1 trial to determine the RP2D of the combination of regorafenib and sildenafil. Both study medications will be taken orally on days 1-21 of each 28-day cycle.~Using a modified 3+3 dose escalation design, 3-6 patients with an advanced solid tumor will be enrolled at each dose level. Additional patients will be enrolled at the MTD until a total of 12 patients have been treated at the MTD.~Eligible patients will have received available standard treatments. Patients with solid tumors for which regorafenib would be considered a standard treatment are eligible as long as regorafenib has not been previously administered.~Blood samples will be collected for correlative studies including PK, PD, and CTCs. Tumor samples archived from a previous biopsy or surgery will also be collected for correlative studies.
This is a phase 1 study of sildenafil in combination with regorafenib in patients with progressive advanced solid tumors. A modified 3+3 dose escalation design will be conducted for the dose escalation of the treatment combination: additional patients will be enrolled at the MTD until a total of 12 patients have been treated at the MTD.