A Phase 1a/1b, First-in-human, Multicenter Study to Assess the Efficacy and Safety of RGT-61159 for Treatment of Patients With Relapsed/Refractory Adenoid Cystic Carcinoma (ACC) or Colorectal Carcinoma (CRC)

Inclusion Criteria: * Histologically confirmed ACC or CRC * Radiographically measurable disease as assessed per RECIST 1.1, with at least 1 site of disease that is measurable and that has not been previously irradiated; or, if the patient has had previous radiation to the target lesion(s), there must be evidence of progression since the radiation * Patients with locally relapsed/refractory (R/R) advanced or metastatic ACC not amenable to potentially curative surgery or radiotherapy and progression of disease within 12 months at study entry * Patients with CRC must have locally R/R advanced or metastatic disease not amenable to potentially curative surgery or radiotherapy; must have been previously treated with, or are not considered candidates for, available therapies including fluoropyrimidines-, oxaliplatin-, and irinotecan-based chemotherapies, anti-VEGF agents, and if RAS wild-type, an anti-EGFR therapy. * Adequate hematologic status, organ function, renal function, liver function and prothrombin time (PT) or INR ≤ 1.5 × ULN and partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT) ≤ 1.5 × ULN * Resolved acute effects of any prior therapy to baseline Exclusion Criteria: * Major surgery or significant traumatic injury within 28 days prior to Cycle 1 Day 1 * Chemotherapy within 14 days prior to Cycle 1 Day 1 * Use of nitrosoureas or mitomycin C within 6 weeks prior to Cycle 1 Day 1 * Radiation therapy within 21 days prior to Cycle 1 Day 1 * Investigational drug use, targeted therapy, or biologic therapy within 28 days or 5 half-lives, whichever is shorter, prior to Cycle 1 Day 1 * Ongoing systemic infection requiring treatment with antibiotic, antiviral, or antifungal treatment * Active known second malignancy * Clinically significant cardiac disease * Infection with human immunodeficiency virus (HIV)-1 or HIV-2 unless it's well-controlled HIV (eg, cluster of differentiation 4 \[CD4\] \> 350/mm3 and undetectable viral load) * Current active liver disease including hepatitis A (hepatitis A \[HepA\] virus immunoglobulin M \[IgM\] positive), hepatitis B (hepatitis B virus \[HBV\] surface antigen positive), or hepatitis C (hepatitis C virus \[HCV\] antibody positive, confirmed by HCV RNA) * Refractory nausea and vomiting, malabsorption, external biliary shunt, or significant small bowel resection that would preclude adequate absorption * Uncontrolled diabetes * Treatment with a long-acting hematopoietic growth factor within 14 days before Cycle 1 Day 1 or a short-acting hematopoietic growth factor within 7 days before Cycle 1 Day 1 * Treatment with high-dose chemotherapy and stem-cell rescue (autologous stem cell transplant) or allogeneic stem cell transplant within 90 days before Cycle 1 Day 1 * Patients with central nervous system (CNS) metastases are not eligible, unless they have completed local therapy and have discontinued the use of corticosteroid throughout this indication for at least 4 weeks before starting treatment in this study * History of solid organ transplantation * Coronavirus disease 2019 (COVID-19) vaccination within 14 days prior to first dose of study drug * Prior treatment with a MYB inhibitor