Dose Evaluation of MK-1966 in Combination With SD-101 in Participants With Advanced Malignancies (MK-1966-001)

Inclusion Criteria:

- Has a histologically- or cytologically-confirmed advanced malignancy that has
progressed after standard-of-care therapy/treatments and there is no available therapy
likely to convey clinical benefit

- Has an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

- Has a life expectancy ≥ 6 months

- Female participants must not be pregnant (negative urine or serum human chorionic
gonadotropin test at screening and again within 72 hours prior to receiving the first
dose of study therapy)

- Female and male participants of reproductive potential must agree to use adequate
contraception during the course of the study through 120 days after study the last
dose of study therapy

- Has ability to submit archived or fresh tumor sample during the screening period

Exclusion Criteria:

- Has had chemotherapy, radiation, or biological cancer therapy within 4 weeks prior to
the first dose of study therapy, or who has not recovered to Common Terminology
Criteria for Adverse Events (CTCAE) grade 1 or better from the adverse events due to
cancer therapeutics administered more than 4 weeks earlier

- Has participated in a study of an investigational agent and received study therapy or
used an investigational device within 28 days of study start

- Is expected to require any other form of antineoplastic therapy while on study

- Is on chronic systemic steroid therapy in excess of replacement doses, or on any other
form of immunosuppressive medication

- Has a history of a malignancy, unless potentially curative treatment has been
completed, with no evidence of malignancy for 5 years

- Has known active central nervous system (CNS) metastases and/or carcinomatous
meningitis

- Has had a severe hypersensitivity reaction to treatment with another monoclonal
antibody

- Has an active autoimmune disease that has required systemic treatment in past 2 years

- Has an active infection requiring therapy

- Has active, current pneumonitis, or a history of (non-infectious) pneumonitis that
required steroids

- Has had a prior stem cell or bone marrow transplant

- Is positive for Human Immunodeficiency Virus (HIV) and/or Hepatitis B or C

- Has known psychiatric disorder that would interfere with fulfilling the requirements
of the study

- Is a regular user of any illicit drugs or had a recent history of substance abuse

- Has symptomatic ascites or pleural effusion

- Is pregnant or breastfeeding or expecting to conceive or father children within the
projected duration of the study

- Has clinically significant heart disease that affects normal activities

- Has had major surgery (requiring at least a 3 day hospital stay) in the past 28 days

- Has received a live vaccine within 30 days prior to first dose of study therapy