Substudy 02C: Safety and Efficacy of Pembrolizumab in Combination With Investigational Agents or Pembrolizumab Alone in Participants With Stage III Melanoma Who Are Candidates for Neoadjuvant Therapy (MK-3475-02C/KEYMAKER-U02)

Inclusion Criteria: * Has histologically or cytologically confirmed melanoma * Has clinically detectable and resectable Stage IIIB or IIIC or IIID melanoma amenable to surgery * Has been untreated for Stage IIIB, IIIC or IIID melanoma * surgical resection of primary melanoma is allowed * prior radiotherapy to the primary melanoma is allowed * Has provided a baseline tumor biopsy * Male participants who receive gebasaxturev are abstinent from heterosexual intercourse or agree to use contraception during the intervention period and for at least 120 days after the last dose of gebasaxturev * Male participants who receive ATRA are abstinent from heterosexual intercourse or agree to use contraception during the intervention period and for at least 7 days after the last dose of ATRA * Female participants are not pregnant or breastfeeding and are either not a woman of child-bearing potential (WOCBP) OR use a contraceptive method that is highly effective or are abstinent from heterosexual intercourse during the intervention period and for at least 120 days after the last dose of pembrolizumab, vibostolimab, gebasaxturev, or MK-4830, favezelimab + pembrolizumab, or 30 days after the last dose of ATRA, whichever occurs last * Has adequate organ function * Has resolution of toxic effect(s) of the most recent prior therapy to Grade 1 or less (except alopecia) Exclusion Criteria: * Has a diagnosis of immunodeficiency or is receiving immunosuppressive therapy within 7 days before t…