This study is to assess the safety and antitumor activity of ABL103 plus pembrolizumab, with or without taxane, in advanced or metastatic solid tumors.

Inclusion Criteria:

• Subject must understand and be willing to provide informed consent and be able to comply with the study procedures and restrictions.
• Subjects must be ≥18 years of age on the day of signing the informed consent form (ICF).
• Subject must have a histologically or cytologically confirmed locally advanced unresectable, or metastatic solid tumor.
• Subject must be relapsed or be refractory to available standard therapy or they must be intolerant of available standard therapy.
• Subject must meet Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 assessed 7 days before the first administration of the study drug.
• Subjects must be recovered from AEs from prior therapy to Grade 1 or the baseline grade more than 14 days prior to the first administration of the study drug, except alopecia or Grade 2 toxicities that are deemed stable or irreversible (e.g., peripheral neuropathy)
• Subjects who have AEs due to previous anticancer therapies must have recovered to ≤Grade 1 or baseline. Subject with endocrine-related AEs who are adequately treated with hormone replacement or subjects who have ≤Grade 2 neuropathy are eligible.
• Subjects must have adequate hematologic, renal, hepatic, and thyroid function at screening and within 7 days prior to the first administration of study drug.
• Female subjects who are not surgically sterile or postmenopausal must agree to use a highly effective method of birth control (2 methods strongly recommended) during the study and for 6 months following the last dose of ABL103/pembrolizumab.
• Female subjects of childbearing potential must have a negative serum pregnancy test at screening and within 7 days prior to Cycle 1 Day 1 (C1D1).
• Male subjects with female partner(s) of childbearing potential must agree to use contraception and and must not donate sperm during the treatment period with ABL103 and taxane and for at least 6 months after the final administration of ABL103 and taxane.
• Male subjects with a pregnant or breastfeeding partner(s) must agree to remain abstinent or use a condom throughout the study period, and for at least 6 months after the final administration of ABL103 and taxane, and during the partner's pregnancy or breastfeeding period. When using a male condom, the partner must also use an additional method of contraception acceptable for female subjects.

Exclusion Criteria:

• Subject has received prior anticancer monoclonal antibody treatment or investigational therapy (agent or device) for which the pharmacologic or toxicity profile is not expected to have resolved prior to the first administration of the study drug. A minimum of 28 days is generally recommended for agents with known delayed toxicities or prolonged biological activity, unless otherwise justified.
• Subject has received prior radiotherapy within 2 weeks of the first administration of study drug, or has radiation-related toxicities, requiring corticosteroids.
• Subject has received any prior immunotherapy and was discontinued from the treatment due to a Grade 3 or higher irAE (except endocrine disorders that can be treated with replacement therapy) or was discontinued from that treatment due to Grade 2 myocarditis or recurrent Grade 2 pneumonitis.
• Subject has received radiation therapy to the lung that is >30 Gy within 6 months of the first dose of study treatment.
• Subject has risk factors for bowel obstruction or bowel perforation, including, but not limited to a history of acute diverticulitis, intra-abdominal abscess, and abdominal carcinomatosis. Subjects with ovarian cancer with a history of abdominal carcinomatosis can be enrolled.