Study to Evaluate VT3989 in Patients With Metastatic Solid Tumors

Who May Qualify: - Part 3 Combination Cohort A: Patients with pathologically diagnosed, metastatic or unresectable malignant mesothelioma (including both pleural and non-pleural) who have not received systemic therapy. - Part 3 Combination Cohort B: Patients with pathologically diagnosed incurable locally advanced (inoperable or recurrent), or metastatic NSCLC with exon 19 deletions or exon 21 L858R mutations, with or without prior treatment with Osimertinib. - Part 3 Combination Cohort C: Patients with pathologically diagnosed metastatic or unresectable malignant pleural mesothelioma who have not received systemic chemotherapy. - tumors that can be measured on scans v1.1 for non-pleural mesothelioma or other solid tumors or modified RECIST v1.1 for malignant pleural mesothelioma. mRECIST may be used for pleural extension of non-pleural mesothelioma or for mixed pleural and peritoneal (or other) mesothelioma. - ECOG: 0-1. - your organs (liver, kidneys, etc.) are working well enough based on blood testss, including the liver, kidneys, and hematopoietic system. Who Should NOT Join This Trial: - Active brain metastases or primary CNS (central nervous system) tumors. - History of leptomeningeal metastases - Active or chronic, uncontrolled bacterial, viral, or fungal infection(s) requiring systemic therapy - Known HIV positive or active Hepatitis B or Hepatitis C - Clinically significant cardiovascular disease and prior exposure to cardiotoxic agents. - Corrected QT (QTcF) interval \> 470 msec (using Fridericia's correction formula). - Additional active malignancy that may confound the assessment of the study endpoints - Women who are pregnant or breastfeeding - Prior treatment with TEAD inhibitor. Always talk to your doctor about whether this trial is right for you.