The purpose of this study is to characterize safety and to determine the recommended phase 2 regimen (RP2R) for JNJ-87801493 in combination with T-cell engagers (TCEs) [Part A: Dose Escalation] and to further assess the safety of JNJ-87801493 at the RP2R in combination with TCEs [Part B: Dose Expansion].

Inclusion Criteria:

• Histologic documentation of B-cell NHL. All participants in part 1 must have relapsed or refractory disease with no other approved therapies available that would be more appropriate in the investigator's judgment. In Part 2, participants with diffuse large B-cell lymphoma (DLBCL) or other high-grade B cell lymphoma and participants with transformed lymphoma from low-grade B cell malignancies who relapsed or failed to respond to only one prior systemic treatment regimen can be included
• Part 1 participants must have evaluable or measurable disease and Part 2 participants must have measurable disease; all as defined by the Lugano criteria for non-Hodgkin lymphoid malignancies (NHL) and the international workshop on Waldenstrom's Macroglobulinemia (IWWM-6) for WM
• Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2
• Hematologic laboratory parameters must meet the required criterias and the values must be without a transfusion or growth factors for at least 7 days prior to the first dose of study drug
• Participants of childbearing potential must have a negative highly sensitive serum pregnancy test (beta (β)-human chorionic gonadotropin) at screening and within 72 hours of the first dose of study treatment and must agree to further serum or urine pregnancy tests during the study.

Exclusion Criteria:

• Known active central nervous system involvement (CNS) or leptomeningeal involvement. CNS involvement may be allowed in specific cohorts as determined by the Study Evaluation Team (SET)
• Prior solid-organ transplantation
• Prior treatment with JNJ-80948543 and/or JNJ-75348780. In addition, history of known allergies, hypersensitivity, or intolerance to either JNJ-80948543, JNJ-75348780, or JNJ-87801493 or its excipients
• Chemotherapy, targeted therapy, or immunotherapy within 2 weeks before the first dose of study treatment. For investigational agents where the half-life is known, there should be a treatment-free window of at least 2 weeks or 5 half-lives. For checkpoint blockade therapy (example, anti-programmed cell death protein-1 [anti-PD-1]), a washout period of up to 6 weeks may be considered
• Malignancy diagnosis other than the disease under study within 1 year prior to screening. Exceptions are squamous and basal cell carcinoma of the skin, carcinoma in situ of the cervix and any malignancy that is considered cured or has minimal risk of recurrence within 1 year of first dose of the study drugs in the opinion of both the investigator and sponsor's medical monitor
• Autoimmune or inflammatory disease requiring systemic corticosteroids or other immunosuppressive agents within 1 year prior to first dose of study treatment
• Evidence of active viral, bacterial, or uncontrolled systemic fungal infection requiring systemic treatment within 7 days before the first dose of study treatment
• Abnormal cardiac function

The data sharing policy of Johnson & Johnson Innovative Medicine is available at innovativemedicine.jnj.com/our-innovation/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu