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.