A Study of Pembrolizumab (MK-3475) in Pediatric Participants With an Advanced Solid Tumor or Lymphoma (MK-3475-051/KEYNOTE-051)

Inclusion Criteria: * Between 6 months and \<18 years of age on day of signing informed consent is documented. * Histologically- or cytologically-documented, locally-advanced, or metastatic solid malignancy or lymphoma that is incurable and has failed prior standard therapy, or for which no standard therapy exists, or for which no standard therapy is considered appropriate * Any number of prior treatment regimens * Tissue (or lymph node biopsy for rrcHL participants) available from an archival tissue sample or, if appropriate, a newly obtained core or excisional biopsy of a tumor lesion not previously irradiated * Advanced melanoma or PD-L1-positive advanced, relapsed, or refractory solid tumor or lymphoma * Measurable disease based on RECIST 1.1 (Or based on IWG \[Cheson, 2007\] \[i.e., measurement must be \>15 mm in longest diameter or \>10 mm in short axis\] for rrcHL participants) * Participants with neuroblastoma with only metaiodobenzylguanidine (MIBG)-positive evaluable disease may be enrolled * Lansky Play Scale ≥50 for participants from 6 months up to and including 16 years of age; or Karnofsky score ≥50 for participants \>16 years of age * Adequate organ function * Female participants of childbearing potential should have a negative urine or serum pregnancy test within 72 hours before the first dose of study medication * Female participant is not a woman of childbearing potential (WOCBP) or is a WOCBP who is abstinent from heterosexual intercourse or using contrace…