Inclusion Criteria:  Histologically or cytologically confirmed advanced or metastatic EGFR-positive selected cancer types: Advanced or metastatic NSCLC, EGFR WT: disease has progressed after ≥ 1 prior lines of therapy which must have included a platinum-based doublet in combination with PD1/PD-L1 antibody or must have received an anti-PD1/PD-L1 antibody prior to or after a platinum-based doublet Advanced, unresectable, or metastatic gastric/GEJ adenocarinoma: after ≥ 1 prior chemotherapy regimen including a platinum and fluoropyrimidine doublet Advanced or metastatic HCC (BCLC C or B not amenable or refractory to locoregional therapy), hepatobiliary-, or pancreatic adenocarcinoma: after ≥1 prior line of an approved SOC therapy for the respective disease type or to whom the available SOC is not appropriate in the opinion of the investigator Adequate organ function Phase 1: Evaluable or measurable disease per RECIST v1.1 Phase 2a: Measurable disease per RECIST v1.1  Exclusion Criteria:  Treatment with systemic anticancer therapy including investigational agent within 4 weeks of the first dose of study drug, 6 weeks for mitomycin C or nitrosoureas, 2 weeks (or 5 half-lives whichever is longer) for using fluorouracil or small molecule targeted drugs, 2 weeks for using traditional Chinese medicine with anti-tumor indication. Radiation therapy within 2 weeks before 1st dose of study drug or unresolved toxicity from previous radiotherapy History of any other malignancy known to be active, with the exception of completely removed in situ cervical intra-epithelial neoplasia, non-melanoma skin cancer, DCIS, early stage prostate cancer that has been adequately treated, and other cancers from which the patient has been disease free for 3 years or longer Currently active in any other clinical study, or administration of other investigational agent