Study to Evaluate VT3989 in Patients With Metastatic Solid Tumors

Inclusion Criteria:

• Part 3 Combination Cohort A: Patients with pathologically diagnosed, metastatic orunresectable malignant mesothelioma (including both pleural and non-pleural) whohave not received systemic therapy.

• Part 3 Combination Cohort B: Patients with pathologically diagnosed incurablelocally advanced (inoperable or recurrent), or metastatic NSCLC with exon 19deletions or exon 21 L858R mutations, with or without prior treatment withOsimertinib.

• Measurable disease per RECIST v1.1 for non-pleural mesothelioma or other solidtumors or modified RECIST v1.1 for malignant pleural mesothelioma. mRECIST may beused for pleural extension of non-pleural mesothelioma or for mixed pleural andperitoneal (or other) mesothelioma.

• ECOG: 0-1.

• Adequate organ functions, including the liver, kidneys, and hematopoietic system.

Exclusion Criteria:

• Active brain metastases or primary CNS (central nervous system) tumors.

• History of leptomeningeal metastases

• Active or chronic, uncontrolled bacterial, viral, or fungal infection(s) requiringsystemic therapy

• Known HIV positive or active Hepatitis B or Hepatitis C

• Clinically significant cardiovascular disease

• Corrected QT (QTcF) interval > 470 msec (using Fridericia's correction formula);except for Part 2 Expansion Cohort 3, the QTcF interval criteria is > 450 msec).

• Additional active malignancy that may confound the assessment of the study endpoints

• Women who are pregnant or breastfeeding

• Prior treatment with TEAD inhibitor, except for EHE patients.