DLTs were assessed during the first treatment cycle (28 days) & were defined as any drug-related toxicity that occurred during the 28-day DLT period and included:

• Non-hematologic toxicity grade ≥3 (except diarrhea, nausea, and vomiting unless lasting >3 days despite optimal supportive care);

• Confirmed (with a second measurement after 24 hours) non-hematologic appropriately graded laboratory findings of Grade ≥3 that were ≤ Grade 1 at baseline;

• Hematologic toxicity:

  • Grade 4 neutropenia ≥5 days, or Grade 3 neutropenia with fever (fever is >38.4ºC)
  • Grade 4 thrombocytopenia, or Grade 3 thrombocytopenia lasting >7 days or with bleeding; and

• Any other toxicity assessed as related to MK-4621, and which, in the opinion of the Investigator and the Sponsor physician constituted a DLT.

The number of participants who experienced a DLT is presented by NCI CTCAE version 4.03 severity grade.

Blood samples were collected at various time points for the analysis of mean fold change from baseline in cytokine release for selected cytokines (Interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-a]) in plasma.

Blood samples were collected at various time points for the analysis of mean fold change from baseline in cytokine release for selected cytokines (Interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-a]) in plasma.

Blood samples were collected at various time points for the analysis of mean fold change from baseline in cytokine release for selected cytokines (Interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-a]) in plasma.

Blood samples were collected at various time points during Cycle 1 for the determination of MK-4621 AUC0-t on Day 1, which was defined as the AUC from the start time of dosing to the time of the last observed concentration above the limit of quantitation (LOQ).

Blood samples were collected at various time points during Cycle 1 for the determination of MK-4621 AUC0-t on Day 25, which was defined as the AUC from the start time of dosing to the time of the last observed concentration above the limit of quantitation (LOQ).

Blood samples were collected at various time points during Cycle 1 for the determination of MK-4621 Cmax on Day 1.

Blood samples were collected at various time points during Cycle 1 for the determination of MK-4621 Cmax on Day 25.

Sequential participant tumor biopsies were assessed via immunohistochemistry for the presence of tumor infiltrating CD3 T cell co-receptor-marked cells and Ki-67 nuclear protein-marked cells in tumor biopsies. CD3 is a marker of T cells and KI-67 is a cell marker of proliferation and activation. The percentage of positive CD3-marked cells and double-positive CD3 and Ki-67 nuclear protein-marked cells in tumor biopsies predose on Day 1 are presented.

Sequential participant tumor biopsies were assessed via immunohistochemistry for the presence of tumor infiltrating CD3 T cell co-receptor-marked cells and Ki-67 nuclear protein-marked cells in tumor biopsies. CD3 is a marker of T cells and KI-67 is a cell marker of proliferation and activation. The percentage of positive CD3-marked cells and double-positive CD3 and Ki-67 nuclear protein-marked cells in tumor biopsies postdose on Day 25 are presented.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.4 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with injectable liver tumors or liver metastases were to receive escalating doses of MK-4621 via IT/IL injection once each week over a period of 4 weeks. Participants were to have been able to continue to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). (Group B was not started for business reasons. Development will continue with new protocol.)

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.4 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.6 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.

Participants with transdermally/transmucosally injectable tumors including cutaneous, subcutaneous or lymph node injectable tumors received MK-4621 0.8 mg via IT/IL injection twice each week over a period of 4 weeks during Cycle 1. Participants may have continued to receive study treatment beyond Cycle 1 for the remaining duration of the study as long as clinical benefit (no overt clinical progression or toxicity considered to be intolerable as per Investigator's assessment) was present (could have been up to approximately 2 years). Each cycle was 28 days.