• Phase 1 - Dose Escalation Phase: Advanced solid tumor that has progressed during or after treatment with approved therapies or for which there is no standard effective therapy available

• Phase 2 - Dose Expansion Phase: One of the following advanced solid tumors that is RAS-mutated and has progressed during or after treatment with at least one approved therapy or for which there is no standard effective therapy available: :

• Colon Cancer with a RAS mutation

• Pancreatic Cancer with a RAS mutation

• Other Solid Tumor with RAS Mutation

• Ocular melanoma, which includes melanoma that develops in the sclera, retina, uvea (iris, choroid layer, and ciliary layer), or conjunctiva or other cancers with a GNAQ or GNA11 mutation

• Measurable disease by RECIST v1.1

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

• Adequate bone marrow function

• Absolute neutrophil count (ANC) ≥ 1500/mm3

• Platelets ≥ 100,000/mm3

• Hemoglobin \> 9 g/dL (untransfused)

• Adequate renal function

• Creatinine ≤ 1.5 x upper limit of normal (ULN) for the laboratory or calculated or actual creatinine clearance ≥ 60 mL/min

• Adequate hepatic function

• Total bilirubin ≤ 1.5 x ULN for the laboratory Exception: If a patient has documented Gilbert's syndrome and a total bilirubin is \> 1.5 x ULN for the laboratory, the total bilirubin requirement may be waived provided the direct bilirubin is within normal limits (WNL) for the laboratory.

• Aspartate aminotransferase (AST) ≤ 3.0 x ULN for the laboratory

• Alanine aminotransferase (ALT) ≤ 3.0 x ULN for the laboratory

• Note: For the expansion cohorts, in patients with documented liver metastasis, the AST and ALT requirements will be ≤ 5 x ULN for the laboratory

• Non-hematologic toxicities from previous cancer therapies resolved to ≤ grade 1 except chronic residual toxicities that in the opinion of the investigator are not clinically relevant given the known safety/toxicity profiles of neratinib and sodium valproate (eg, alopecia, changes in pigmentation, stable endocrinopathies, neuropathy, skin toxicities)

• International normalized ratio (INR) is ≤ 1.5 and activated partial thromboplastin time (aPTT) ≤ 1.5 x ULN for the laboratory

• A woman of childbearing potential (WCBP), defined as a woman who is \< 60 years of age and has not had a hysterectomy, must have a documented negative serum pregnancy test within 7 days prior to initiating study treatment

• WCBP and a male patient with a partner who is a WCBP must agree to use a medically accepted method for preventing pregnancy for the duration of study treatment and for 2 months following completion of study treatment

• Ability to understand and willingness to sign a written informed consent document