• To evaluate the safety and tolerability of escalating doses of ERAS-601 when administered as a monotherapy and in combination with other cancer therapies in study participants with advanced or metastatic solid tumors.
• To determine the Maximum Tolerated Dose (MTD) and/or recommended dose (RD) of ERAS-601 when administered as a monotherapy and in combination with other cancer therapies.
• To characterize the pharmacokinetic (PK) profile of ERAS-601 when administered as a monotherapy and in combination with other cancer therapies.
• To evaluate the antitumor activity of ERAS-601 when administered as a monotherapy and in combination with other cancer therapies.

This is a first-in-human, Phase 1/1b, open-label, multicenter clinical study of ERAS-601 as a monotherapy and in combination with other cancer therapies. The study will commence with dose escalation of ERAS-601 monotherapy, followed by dose escalation of ERAS-601 in combination with other cancer therapies. Once the monotherapy MTD and/or RD has been determined, then dose expansion of ERAS-601 monotherapy may commence with enrollment of study participants with advanced or metastatic solid tumors harboring specific molecular alterations. Once the combination therapy MTD and/or RD has been determined, then dose expansion of that combination may commence with enrollment of study participants with advanced or metastatic solid tumors harboring specific molecular alterations.

Inclusion Criteria:

• Age ≥ 18 years
• Willing and able to give written informed consent
• Have histologically or cytologically confirmed advanced or metastatic solid tumor
• There is no available standard systemic therapy available for the patient's tumor histology and/or molecular biomarker profile; or standard therapy is intolerable, not effective, or not accessible; or patient has refused standard therapy
• Able to swallow oral medication
• Have Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1
• Adequate cardiovascular, hematological, liver, and renal function
• Willing to comply with all protocol-required visits, assessments, and procedures

Exclusion Criteria:

• Previous treatment with a SHP2 inhibitor
• Documented PTPN11 mutations
• Is currently receiving another study therapy or has participated in a study of an investigational agent and received study therapy within 4 weeks of the first dose of ERAS-601
• Received prior palliative radiation within 7 days of Cycle 1, Day 1
• Have primary central nervous system (CNS) disease or known active CNS metastases and/or carcinomatous meningitis
• Prior surgery (e.g., gastric bypass surgery, gastrectomy) or gastrointestinal dysfunction (e.g., Crohn's disease, ulcerative colitis, short gut syndrome) that may affect drug absorption
• Active, clinically significant interstitial lung disease or pneumonitis
• History of thromboembolic or cerebrovascular events ≤ 12 weeks prior to the first dose of study treatment
• History or current evidence of retinal vein occlusion (RVO) or current risk factors for RVO
• Have any underlying medical condition, psychiatric condition, or social situation that, in the opinion of the Investigator, would compromise study administration as per protocol or compromise the assessment of AEs
• Are pregnant or breastfeeding or expecting to conceive or father children within the projected duration of the trial