This study will have two Phases: Phase 1a and Phase 1b. The goal of Phase 1a of this clinical study is to learn more about the safety, tolerability and dosing of study drug KITE-197, in participants with relapsed or refractory large B-cell lymphoma (r/rLBCL). The goal of Phase 1b of this clinical study is learn about the effectiveness of the recommended dose of KITE-197 in participants with r/r LBCL.

The primary objectives of this study are:

Phase 1a: To evaluate the safety of KITE-197 in participants with r/r LBCL and determine the target dose level for Phase 1b.

Phase 1b: To evaluate the efficacy of KITE-197 in participants with r/r LBCL as measured by the complete remission (CR) rate.

Participants will be followed for approximately 6 months after the infusion of KITE-197 before transitioning to a separate Kite long-term follow-up study KT-US-982-5968, in which they will be followed for the remainder of the 15-year follow-up period.

Key Inclusion Criteria:

• Relapsed or Refractory Large B-cell Lymphoma
• At least 1 measurable lesion
• Adequate organ and bone marrow function

Key Exclusion Criteria:

• History of malignancy other than nonmelanoma skin cancer or carcinoma in situ (eg, cervix, bladder, breast) unless disease free for at least 2 years
• History of Richter's transformation of chronic leukemic lymphoma
• History of allogenic stem cell transplant (SCT)
• Autologous SCT within 6 weeks of planned KITE-197 infusion
• Prior CD19 targeted antibody, such as tafasitamab and loncastuximab with the exception of individuals who have previously achieved an objective response to such therapy and their tumor expresses CD19 by International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (IHC) at the time of screening. Individuals who meet these criteria may be eligible
• Prior treatment with bendamustine within 6 months of enrollment
• Prior CAR therapy or other genetically modified cell therapy
• Presence or suspicion of fungal, bacterial, viral, or other infection that is uncontrolled or requiring IV antimicrobials for management
• History of HIV infection or acute or chronic active hepatitis B or C infection
• History or presence of a clinically significant central nervous system (CNS) disorder Note: Prior or active CNS involvement by lymphoma is not an exclusion criterion.
• History of myocardial infarction, cardiac angioplasty or stenting, unstable angina, New York Heart Association Class II or greater congestive heart failure, or other clinically significant cardiac disease within 12 months before enrollment
• Presence of primary immunodeficiency
• History of autoimmune disease (eg, Crohn's disease, rheumatoid arthritis, systemic lupus) resulting in end organ injury or requiring systemic immunosuppression/systemic disease modifying agents within the last 2 years
• History of symptomatic deep vein thrombosis (DVT) or pulmonary embolism within 3 months before enrollment. Catheter induced DVT which has been treated for at least 6 weeks prior to enrollment is permitted
• Females of childbearing potential who are pregnant or breastfeeding because of the potentially dangerous effects of the preparative chemotherapy on the fetus or infant

Note: Other protocol defined Inclusion/Exclusion criteria may apply.