This is a multicenter, randomized, double-blind, parallel-group, 2 treatment group, repeated dose study to compare the PK, efficacy, safety, and immunogenicity of AVT32-DRL_PB (proposed Keytruda® biosimilar) versus Keytruda (pembrolizumab) when administered as monotherapy in participants with fully resected Stage IIB/C or Stage III melanoma requiring adjuvant treatment with pembrolizumab. Eligible participants will be randomized in a 1:1 ratio to the AVT32-DRL_PB or Keytruda treatment group and stratified by sex (female versus male) and body weight category (≤75 kg versus >75 kg). Study treatments will be administered every 3 weeks (Q3W) as an intravenous (IV) infusion over 30 minutes (1 administration Q3W is 1 treatment cycle). The administered pembrolizumab dose will be 200 mg Q3W for both treatment groups.

Inclusion Criteria:

• Participants (male/female) ≥18 years of age at the time of signing the ICF.
• Have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1 at the time of enrollment.
• Participants with Stage IIB, IIC, or III histologically confirmed cutaneous melanoma

Exclusion Criteria:

• Have had a solid organ transplant or bone marrow (stem cell) transplant that used donor stem cells (allogenic).
• Has received prior systemic anticancer therapy for melanoma including investigational agents.
• Participants with a history of mucosal or uveal melanoma, even if diagnosis and treatment were completed >5 years ago.