A Trial of RSC-1255 for Treatment of Patients With Advanced Malignancies

Inclusion Criteria (Key Factors): 1. Has pathologically confirmed advanced or metastatic malignancy characterized by one or more of the following: * Participant is intolerant of existing therapy(ies) known to provide clinical benefit for their condition * Malignancy is refractory to existing therapy(ies) known to potentially provide clinical benefit * Malignancy has progressed on standard therapy 2. Has evaluable or measurable tumor(s) in dose-escalation by standard radiological and/or laboratory assessments as applicable to their malignancy. 3. Has adequate performance status (PS): Eastern Co-operative Oncology Group (ECOG). 4. Is age ≥ 18 years. 5. Has either tissue agnostic tumors and documented RAS mutations or with glioblastoma with or without mutation in RAS Exclusion Criteria (Key Factors): 1. Participants receiving cancer therapy at the time of enrollment. 2. Any clinically significant disease or condition affecting a major organ system. 3. Significant cardiovascular disease or electrocardiogram (ECG) abnormalities. 4. Known Gilbert's disease. 5. Has had a previous (within 2 years) or has a current malignancy other than the target cancer. 6. Intermittent hypokalemia 7. Grade 1 or higher nausea, vomiting, diarrhea at baseline due to underlying disease