This early-phase clinical trial is designed for adults with advanced solid tumors that have spread (metastasized) and carry specific genetic mutations in the BRAF and/or NRAS genes—both of which are known to drive cancer progression. The study aims to assess the safety, tolerability, how the body processes the drug (pharmacokinetics), and preliminary antitumor activity of an investigational therapy called KIN-2787. Patients with melanoma and other tumors that have a NRAS or BRAF mutation are eligible for this trial. This trial allows for different types of BRAF mutations. KIN-2787 is a type of targeted therapy known as a RAF inhibitor, which works by interfering with molecular pathways that promote cancer cell growth. The trial will evaluate KIN-2787 both as a standalone treatment and in combination with binimetinib, a MEK inhibitor. Although binimetinib is FDA-approved for use in combination with a BRAF inhibitor in certain forms of melanoma, its use in this study is investigational. The primary goal is to determine whether KIN-2787—alone or with binimetinib—is safe and well-tolerated in participants with advanced BRAF- or NRAS-mutant cancers. A secondary aim is to explore whether the treatment can slow or halt tumor growth in these patients.