A Study of MK-1484 as Monotherapy and in Combination With Pembrolizumab (MK-3475) In Advanced or Metastatic Solid Tumors (MK-1484-001)

The main inclusion and exclusion criteria include but are not limited to the following:

Inclusion Criteria:

* Has a histologically- or cytologically-confirmed advanced/metastatic solid tumor by pathology report and has received, or been intolerant to, all treatment known to confer clinical benefit.
* Has measurable disease by Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 as assessed by the local site investigator/radiology.
* Has normal cardiac function based on transthoracic echocardiogram (TTE) or multigated acquisition scan (MUGA)
* Has provided an evaluable archival or newly obtained tumor tissue sample for biomarker analysis.
* Has adequate organ function.
* A male participant must agree to use contraception and should refrain from donating sperm during the specified period(s) of at least 120 days after study interventions.
* A female participant is eligible to participate if she is not pregnant or breastfeeding and at least 1 of the following: not a woman of childbearing potential (WOCBP) or a WOCBP who agrees to follow the contraceptive guidance during the treatment period for at least 120 days after study intervention.

Exclusion Criteria:

* Has and chemotherapy, definitive radiation, or biological cancer therapy within 4 weeks (2 weeks for palliative radiation) before the first dose of study intervention, or has not recovered to Common Terminology Criteria for Adverse Events (CTCAE) Grade 1 or better from any AEs that were due to cancer therapeutics administered more than 4 weeks earlier (this includes participants with previous immunomodulatory therapy with residual immune-related AEs). Participants receiving ongoing replacement hormone therapy for endocrine immune-related AEs will not be excluded from participation in this study.
* Has a history of a second malignancy, unless potentially curative treatment has been completed with no evidence of malignancy for 2 years.
* Has clinically active central nervous system (CNS) metastases and/or carcinomatous meningitis.
* Has had a severe hypersensitivity reaction to treatment with a monoclonal antibody and/or components of the study interventions.
* Has an active infection requiring therapy.
* Has a history of interstitial lung disease.
* Has a history of (noninfectious) pneumonitis that required steroids or has current pneumonitis.
* Has an active autoimmune disease that has required systemic treatment in the past 2 years except vitiligo or resolved childhood asthma/atopy.
* Participants with known human immunodeficiency virus (HIV) and/or hepatitis B or C infections, or known to be positive for hepatitis B surface antigen (HBsAg)/hepatitis B virus (HBV) DNA or hepatitis C Antibody or ribonucleic acid (RNA).
* Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the participant's participation for the full duration of the study, make administration of the study drugs hazardous, or make it difficult to monitor adverse effects such that it is not in the best interest of the participant to participate.
* Has known psychiatric or substance abuse disorders that would interfere with the participant's ability to cooperate with the requirements of the study.
* Has not fully recovered from any effects of major surgery without significant detectable infection. Surgeries that required general anesthesia must be completed at least 2 weeks before first study intervention administration. Surgery requiring regional/epidural anesthesia must be completed at least 72 hours before first study intervention administration and participants should be recovered.
* Has received a live or live-attenuated vaccine within 30 days before the first dose of study intervention.
* Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days before the start of study treatment.
* Has had an allogeneic tissue/solid organ transplant in the last 5 years or has evidence of graft-versus-host disease.
* Has received any prior interleukin-2 (IL-2) based therapy.