Study of DCC-3084 in Participants With Advanced Malignancies Driven by the Mitogen-Activated Protein Kinase (MAPK) Pathway

Inclusion Criteria: General Inclusion Criteria ModA Part 1 and 2: * Able to take oral medication * If a female is of childbearing potential, must have a negative pregnancy test prior to enrollment and all participants agree to follow the contraception requirements * Adequate organ function and electrolytes * Eastern Cooperative Oncology Group Performance Status (ECOG-PS) of 0 to 1 at Screening * Has a life expectancy of more than 6 months * In addition to these general inclusion criteria, participants must meet all the module cohort-specific inclusion criteria Inclusion Criteria ModA Part 1 Cohort Specific: * Pathologically confirmed diagnosis of solid cancer and documentation of Kirsten rat sarcoma (KRAS), Harvey rat sarcoma virus (HRAS), neuroblastoma ras viral oncogene homolog (NRAS), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), v-raf murine sarcoma viral oncogene homolog C1(CRAF), and/or neurofibromatosis 1 (NF1) mutation * Have exhausted all available standard of care therapies that are known to provide benefit for the participant's condition, as judged by the Investigator Inclusion Criteria ModA Part 2 Cohort Specific: * Documented BRAF gene mutation * Pathologically confirmed diagnosis with PD after at least one prior line of therapy in the advanced or metastatic setting Exclusion Criteria: General Exclusion Criteria ModA Part 1 and 2: * Prior treatment with certain BRAF dimer inhibitors * Female participant is pregnant or lactating * Received any prior or concurrent medications or therapies known to be prohibited with DCC-3084 within 14 days * Received any prior antitumor therapy or any investigational therapy within a specified timeframe prior to first dose of DCC-3084 * Known allergy or hypersensitivity to any component of the study drug * Invasive malignancy within 2 years prior to the first dose of study drug other than the study indication or specific types of cancer treated with curative intent * Have not recovered from all clinically relevant toxicities from prior therapy * Impaired cardiac function * History of recent thrombotic or embolic events * Malabsorption syndrome or other illness that could affect oral absorption * Major surgery within 28 days of the first dose of study drug * In addition to the general exclusion criteria, participants will also be excluded based on the cohort-specific exclusion criteria Exclusion Criteria: Module A Part 2 Cohort Specific: • Has known co-occurring mutation of KRAS, HRAS, NRAS, NF1, epidermal growth factor receptor, Phosphoinositide-3-kinase, catalytic, alpha polypeptide (PI3KCA), or Phosphatase and TENsin homolog deleted on chromosome 10 (PTEN)