A Study to Evaluate Zilovertamab Vedotin (MK-2140) for Relapsed or Refractory Diffuse Large B-Cell Lymphoma (DLBCL) (MK-2140-004)

Inclusion Criteria:

* Has relapsed or refractory (rr) DLBCL; has progressed after at least 2 lines of prior therapy; and has progressed after auto- stem cell transplant (SCT) or are auto-SCT ineligible. Must have received prior multiagent regimen that includes an alkylating agent. anthracycline, and anti-CD20 (cluster of differentiation 20) monoclonal antibody.
* Has histologically confirmed diagnosis of DLBCL.
* Has radiographically measurable DLBCL per the Lugano Response Criteria.
* Should either be post- chimeric antigen receptor T cell therapy (CAR-T) failure or ineligible for CAR-T (for any reason).
* Life expectancy of at least 3 months.
* Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 assessed within 7 days before time of enrollment.
* Has adequate organ function.

Exclusion Criteria:

* Has received a diagnosis of Primary mediastinal B-cell lymphoma (PMBCL).
* Has undergone solid organ transplant at any time.
* Has a history of any clinically significant cardiovascular conditions within 6 months of screening or serious cardiac arrhythmia requiring medication.
* Has known history of liver cirrhosis.
* Has pericardial effusion or clinically significant pleural effusion.
* Has ongoing Grade \>1 peripheral neuropathy.
* Has a history of a second malignancy, unless potentially curative treatment has been completed with no evidence of malignancy for 2 years.
* Transformed DLBCL from indolent lymphoma.
* In participants with prior allo-SCT, acute graft versus host disease (GVHD) or ongoing evidence of chronic GVHD.
* Has received prior systemic anticancer therapy, including investigational agents within 4 weeks prior to the first dose of study intervention.
* Has received prior radiotherapy within 28 days of start of study intervention. Participants.

must have recovered from all radiation-related toxicities.

* Has ongoing corticosteroid therapy (exceeding 30 mg daily of prednisone equivalent).
* Has received a live or live-attenuated vaccine within 30 days before the first dose of study intervention.
* Is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks before the first dose of study intervention.
* Has known active central nervous system (CNS) lymphoma involvement or active CNS involvement by lymphoma.
* Has an active infection requiring systemic therapy.
* Has a known history of human immunodeficiency virus (HIV) infection.
* Has a known history of hepatitis B or known active hepatitis C virus (HCV).