Study of MK-2118 Administered as Intratumoral Injection as Monotherapy and in Combination With Pembrolizumab (MK-3475) or by Subcutaneous Injection in Combination With Pembrolizumab in the Treatment of Adults With Advanced/Metastatic Solid Tumors or Lymphomas (MK-2118-001)

The purposes of this study are to: 1) assess the safety and tolerability and 2) establish a preliminary recommended Phase 2 dose (RP2D) and/or a maximum tolerated dose (MTD) or a maximum administered dose (MAD) of MK-2118 when administered via intratumoral (IT) injection as monotherapy and in combination with pembrolizumab (MK-3475) intravenous (IV) infusion, or via subcutaneous (SC) injection in combination with pembrolizumab IV infusion in the treatment of adult participants with advanced/metastatic solid tumors or lymphomas. Participants will receive either MK-2118 monotherapy or MK-2118 in combination with pembrolizumab for up to 35 cycles for Arms 1-3 or up to 36 cycles for Arm 4 (up to approximately 2 years). All participants will undergo at least a 24-hour observation period following the first three administrations of MK-2118 (Arms 1-3: Cycle 1 Days 1, 8, and 15. Arm 4: Cycle 1 Days 1 and 8; and Cycle 2 Day 1). Qualified participants who experience radiographic or clinical progression in Arm 1 (MK-2118 Intra-tumoral \[IT\] monotherapy) may switch over to Arm 2 (MK-2118 IT + Pembrolizumab IV Combination Therapy) at an eligible dose. Pharmacokinetic (PK) outcome measures will not be analyzed separately for the switch-over treatment arms, per protocol.