Phase 1 Open-label Study of TRX518 Monotherapy and TRX518 in Combination With Gemcitabine, Pembrolizumab, or Nivolumab

Inclusion Criteria: * Advanced Solid Malignancies: Histologically documented metastatic or locally advanced, incurable solid malignancy (Parts A and B); histologically documented metastatic or locally advanced, incurable solid malignancy for which gemcitabine is clinically appropriate (e.g., non-small cell lung, breast, ovarian, pancreatic, and renal cancer); histologically documented metastatic or locally advanced, incurable solid malignancy for which pembrolizumab (Part D) or nivolumab (Part E) is approved. NOTE: Parts D and E only: Subject has either (1) received treatment with pembrolizumab or nivolumab for ≥4 months with a best response of stable disease and plans to continue treatment with either pembrolizumab or nivolumab in accordance with package insert; or (2) is not currently taking, but is eligible for treatment with, pembrolizumab or nivolumab in accordance with the approved indications for each as referenced in the package insert. * Expected survival of at least 12 weeks after dosing. * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 * Evidence of adequate organ function by standard laboratory tests. * All female subjects of child bearing age must be either surgically sterile, postmenopausal for at least 1 year, or using an acceptable method of contraception. Adequate contraception for both male and female subjects must be used from the beginning of the screening period until at least 8 weeks after the last dose of study drug. Exclusion Criteria: * Hematologic malignancies or multiple myeloma. * Known, clinically important cardiac or respiratory disease * Any concomitant serious physical illness other than cancer (e.g., immune deficiency disease, bleeding disorder, etc.) within 1 year prior to dosing. No history of autoimmune disease. * Active, uncontrolled infections within 7 days of study entry requiring systemic therapy. * Evidence of progression of central nervous system (CNS) metastases or symptomatic CNS metastases within 30 days prior to dosing. * History of known or suspected autoimmune disease with the specific exceptions of vitiligo, atopic dermatitis, or psoriasis not requiring systemic treatment. (Parts C, D and E only). * Clinically-significant gastrointestinal disorders, such as perforation, gastrointestinal bleeding, or diverticulitis (Parts D and E only). * Active autoimmune disease that has required systemic treatment in past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment (Parts D and E only). * History of (non-infectious) pneumonitis that required steroids or current pneumonitis (Parts D and E only). * History of interstitial lung disease (Parts D and E only).