Inclusion Criteria:

• Male or female patients, ≥ 18 years.
• Patients with the ability to understand and give written informed consent for participation in this study including all evaluations and procedures as specified by this protocol.
• Patients agreeing to mandatory tumor tissue biopsy at screening and at the end of Cycle 1, with optional tumor biopsy at the time of disease progression.
  • Note: For baseline tissue samples, a specimen obtained up to 6 weeks prior to initiation of treatment on C1D1 and with no additional anticancer treatment given since biopsy collection.
• Patients with documented (histologically or cytologically proven) unresectable, locally advanced or metastatic malignancies:
  • Urothelial cancer (UC) including cancer of the renal pelvis, ureter, bladder, or urethra with urothelial (transitional cell) cancer as the predominant histology (> 50%);
    • Note: Locally advanced urothelial cancer will include T4b, any N; or any T, N 2-3.
  • Small cell lung cancer (SCLC) with radiographic evidence of extensive stage disease;
    • Note: Extensive stage disease is defined as Stage IV (any T, any N, and M 1a/b), or T3-4 due to multiple lung nodules that are too extensive or have a tumor/nodal volume that is too large to be encompassed in a tolerable radiation plan.
  • Endometrial cancer (EC) of any histological subtype;
  • Cholangiocarcinoma (CCA): unresectable or metastatic adenocarcinoma of the intra- and/or extra-hepatic bile ducts.
• Patients with UC, SCLC, and EC must have received prior anti-PD-(L)1 therapy with a best response of complete response (CR)/partial response (PR) or durable stable disease (SD) (defined as ≥3 months duration of SD) (on PD-[L]1 maintenance therapy in SCLC patients). Patients may have received one or more prior lines of therapy prior to receiving PD-(L)1 therapy, but no additional anticancer treatment since progression on anti-PD-(L)1 therapy. CCA patients will be eligible without prior anti-PD-(L)1 therapy and with at least one prior line of standard of care systemic therapy.
  • Note 1: Patients may have received prior anti-PD-(L)1 as monotherapy or in combination with chemotherapy or other approved agents for their specific tumor type in a clinical study, patients may meet the criterion if the therapy received is already approved in at least one of the major regions of the world; i.e., US, EU, or Japan.
  • Note 2: If a patient has received additional anticancer treatment since progression on anti-PD-(L)1 therapy then the patient will be considered ineligible. CCA patients will be an exception to this criterion.
• Patients with measurable disease according to RECIST v1.1.
• Patients with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1, and anticipated life expectancy of ≥ 3 months).
• Women of childbearing potential agreeing to use a highly effective method of contraception during the study beginning within 2 weeks prior to the first dose and continuing until 6 months after the last study drug dose.
• Male patients agreeing to use an adequate method of contraception starting with the first dose of study drug through 6 months after the last dose of study drug and to refrain from sperm donation during this period.

Exclusion Criteria:

• Women who are pregnant or intending to become pregnant before, during, or within 6 months after the last study drug dose; women who are breastfeeding; women of childbearing potential not using and not willing to use a highly effective method of contraception.
• Patients with central nervous system (CNS) malignancies; patients with known, untreated CNS or leptomeningeal metastases, or spinal cord compression, patients with any of the above not controlled by prior surgery or radiotherapy, or patients with symptoms suggesting CNS involvement for which treatment is required.
  • Note: Patients with treated CNS metastases will be eligible if they
    • had radiotherapy, surgery or stereotactic surgery for the brain or spinal metastases;
    • have no neurological symptoms (excluding Grade ≤ 2 neuropathy);
    • have stable brain or spinal disease on the Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scan within 4 weeks before signing the ICF;
    • must not be undergoing acute corticosteroid therapy or steroid taper. Chronic steroid therapy is acceptable provided that the dose is stable for the last 14 days prior to screening (≤ 10 mg prednisone daily or equivalent).
• Spinal bone metastases are allowed unless imminent fracture or cord compression is anticipated.
• Patients with known or suspected CNS metastases will require a baseline imaging to establish stability of the known lesion, appearance of new brain lesion or progression of existing lesion. MRI imaging is preferred for assessment of CNS lesions.
• Patients with significant cardiovascular disease, such as New York Heart Association (NYHA) cardiac disease, myocardial infarction within 3 months prior to enrollment, unstable arrhythmias, or unstable angina.
  • Note: Patients with known coronary artery disease, congestive heart failure not meeting the above criteria, or ventricular ejection fraction < 50% must be on a stable medical regimen that is optimized in the opinion of the treating physician, in consultation with a cardiologist if appropriate.
• Patients with:
  • Active thrombosis, or a history of deep vein thrombosis or pulmonary embolism, within 4 weeks prior to first study drug dose, unless adequately treated and considered by the Investigator to be stable;
  • Active uncontrolled bleeding or a known bleeding diathesis.
• Patients with a significant pulmonary disease or condition, including:
  • History of interstitial lung disease, pulmonary fibrosis;
  • History of pulmonary inflammatory disease, interstitial or other pneumonitis*, acute respiratory distress syndrome (ARDS).

* Patients with prior evidence of Grade 1 pneumonitis will be eligible provided they were asymptomatic when diagnosed and did not require treatment and provided pneumonitis has resolved prior to entry to this study.

• Patients with a current or recent (within 6 months) significant gastrointestinal disease or condition, including:
  • History of inflammatory bowel disease;
  • Diarrhea ≥ Grade 2 within 2 weeks prior to first study drug dose.
• Patients with a significant ocular disease or condition, including history of an autoimmune or inflammatory disorder; e.g., episcleritis, uveitis, iritis.
  • Note: Patients with a history of dry eye for reasons other than an autoimmune disease or condition may be included if adequately treated. Patients with non-significant, non-inflammatory disorders (e.g., cataracts, glaucoma) will be allowed.
• Patients with an active, known or suspected autoimmune disease, or a documented history of autoimmune disease or syndrome, requiring systemic steroids or other immunosuppressive medications.
  • Note: Exceptions are permitted for type I diabetes mellitus, hypothyroidism only requiring hormone replacement, skin disorders such as vitiligo, psoriasis or alopecia not requiring systemic treatment, conditions not expected to recur in the absence of an external trigger.
• Patients with a history of organ transplantation (e.g., stem cell or solid organ transplant).
• Patients with a known history of human immunodeficiency virus (HIV) (HIV 1/2 antibodies) or known active infection with hepatitis B virus (HBV) (e.g., HBsAg reactive) or hepatitis C virus (HCV) (e.g., HCV RNA [qualitative] is detected). (Inactive HBsAg carriers with prophylactic antiviral agent are allowed).
• Patients with any other serious/active/uncontrolled infection, any infection requiring parenteral antibiotics, or unexplained fever >38ºC within 2 weeks prior to first study drug dose.
• Patients with any other serious, life-threatening, or unstable preexisting medical condition (aside from the underlying malignancy) including significant organ system dysfunction or failure, clinically significant laboratory abnormality(ies), psychiatric disorder or altered mental status which, in the opinion of the Investigator, would either compromise the patient’s safety or interfere with obtaining informed consent, compliance with study procedures, or evaluation of the safety of study drug(s).
• Prior therapy with anti-LAG-3 or anti-TIM-3 or combinations of these 2 antibodies with anti-PD- (L)1 antibody or with any other systemic or localized therapy.
• Any antineoplastic agent for the primary malignancy (standard or investigational) with delayed toxicity within 4 weeks or 5 elimination half-lives, whichever is shortest, prior to the first study drug dose, except for nitrosoureas and Mitomycin C within 6 weeks prior to the first study drug dose.
• Any other investigational treatments within 2 weeks prior to the study; this includes participation in any medical device or supportive care therapeutic intervention studies.
• Radiotherapy:
  • For target lesions within 4 weeks prior to the first study drug dose unless PD has been documented in the lesion following radiotherapy;
  • For non-target lesions within 1 week prior to the first study drug dose.
• Use of live vaccines against infectious diseases (e.g., varicella) 4 weeks prior to the first study drug dose.
• Immunosuppressive or systemic hormonal therapy (> 10 mg daily prednisone equivalent) within 2 weeks prior to the first study drug dose.
• Prophylactic use of hematopoietic growth factors within 1 week prior to the first study drug dose.
• Patients with a history of significant toxicities associated with previous administration of immune checkpoint inhibitors that necessitated permanent discontinuation of that therapy.
• Patients with a known or suspected hypersensitivity to any of the excipients of formulated study drug.
• Patients with unresolved >Grade 1 toxicity associated with any prior antineoplastic therapy except for persistent Grade 2 alopecia, peripheral neuropathy, decreased hemoglobin, lymphopenia, hypomagnesemia, and/or end-organ failure being adequately managed by hormone replacement therapy (HRT).
• Patients with inadequate recovery from any prior surgical procedure, or patients having undergone any major surgical procedure within 4 weeks prior to first study drug dose.
• Patients with known or foreseeable inability, in the opinion of the Investigator, to comply with the protocol requirements.