Study to Evaluate the Safety, Pharmacokinetics, and Activity of GDC-1971 in Combination With Either Osimertinib in Participants With Unresectable, Locally Advanced, or Metastatic Non-Small Cell Lung Cancer, or With Cetuximab in Participants With Metastatic Colorectal Cancer

Exclusion Criteria

• •Treatment with chemotherapy, immunotherapy, biologic therapy, or an investigational agent as anti-cancer therapy within 3 weeks or 5 drug elimination half-lives, whichever is shorter, prior to initiation of study treatment
• •Treatment with endocrine therapy within 2 weeks prior to initiation of study drug, except for hormonal therapy with gonadotropin-releasing hormone agonists or antagonists for endocrine-sensitive cancers
• •Significant traumatic injury or major surgical procedure within 4 weeks prior to Cycle 1, Day 1
• •Positive hepatitis C virus (HCV) antibody test at screening
• •Positive hepatitis B surface antigen (HBsAg) test at screening
• •Known HIV infection
• •Clinically significant history of liver disease, including viral or other hepatitis, current alcohol abuse, or cirrhosis
• •Uncontrolled hypercalcemia
• •Substance abuse, as determined by the investigator, within 12 months prior to screening
• •Poor peripheral venous access
• •Inability or unwillingness to swallow pills
• •Malabsorption syndrome or other condition that would interfere with enteral absorption Chronic diarrhea, short bowel syndrome, or significant upper GI surgery including gastric resection, a history of inflammatory bowel disease (e.g., Crohn's disease or ulcerative colitis), or any active bowel inflammation (including diverticulitis)
• •Serious infection within 4 weeks prior to screening
• •History of malignancy within 3 years prior to screening
• •Known and untreated, or active central nervous system (CNS) metastases (progressing or requiring anticonvulsants or corticosteroids for symptomatic control)
• •Leptomeningeal disease or carcinomatous meningitis
• •History or presence of an abnormal electrocardiogram (ECG) that is deemed clinically significant by the investigator (e.g., complete left bundle branch block, second- or third-degree atrioventricular heart block) or evidence of prior myocardial infarction
• •Left ventricular ejection fraction (LVEF) less than the institutional lower limit of normal (LLN) or \<50%
• •History or evidence of ophthalmic disease
• •History of or active clinically significant cardiovascular dysfunction
• •History of pulmonary firbrosis, organizing pneumonia, or pneumonitis