Participants in the dose escalation/confirmation phase receive a dose level of zilovertamab vedotin (from 1.5 mg/Kg up to 2.5 mg/Kg) plus 750 mg/m^2 cyclophosphamide, 50 mg/m^2 doxorubicin, and 375 mg/m^2 rituximab or rituximab biosimilar (truxima) administered by intravenous (IV) infusion on Day 1 of each 21-day cycle (Q3W) for up to 8 cycles (up to approximately 5.5 months). Participants also receive 100 mg prednisone or prednisolone per day during Days 1-5 of each 21-day cycle for up to 8 cycles (up to approximately 5.5 months).

Participants in the efficacy expansion phase receive the RP2D of zilovertamab vedotin plus 750 mg/m^2 cyclophosphamide, 50 mg/m^2 doxorubicin, and 375 mg/m^2 rituximab or rituximab biosimilar (truxima) administered by intravenous (IV) infusion on Day 1 of each 21-day cycle (Q3W) for up to 8 cycles (up to approximately 5.5 months). Participants also receive 100 mg prednisone or prednisolone per day during Days 1-5 of each 21-day cycle for up to 8 cycles (up to approximately 5.5 months).

IV infusion

DLTs will be evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0 and are defined as any drug-related adverse event (AE) observed during the DLT evaluation period (e.g. Cycle 1) that results in a change to a given dose or a delay in initiating the next cycle. The number of participants with DLTs in Cycle 1 will be reported.

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who experience an AE will be reported.

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who discontinue study treatment due to an AE will be reported.

CRR is defined as the percentage of participants who achieve a Complete Response (CR) per Lugano response criteria [Cheson, B. D., et al 2014] for malignant lymphoma as assessed by the investigator. Assessment includes anatomic imaging with computed tomography (CT) or magnetic resonance imaging (MRI), metabolic imaging with positron emission tomography (PET), and clinical findings including physical examination and bone marrow biopsy results. The percentage of participants with CRR will be reported.

ORR is defined as the percentage of participants who achieve a CR or PR per Lugano response criteria [Cheson, B. D., et al 2014] for malignant lymphoma as assessed by the investigator. Assessment includes anatomic imaging with CT or MRI, metabolic imaging with PET, and clinical findings including physical examination and bone marrow biopsy results. The percentage of participants with ORR will be reported.