A Clinical Trial of MK-1045 and Rituximab in People With Follicular Lymphoma (MK-1045-007)

Inclusion Criteria:

* Has biopsy-proven, previously untreated, histologically confirmed cluster of differentiation (CD)19-positive and CD20-positive classical follicular lymphoma (FL), with Ann Arbor Stage II-IV disease and a Follicular Lymphoma International Prognostic Index (FLIPI) score of 2-5.
* Has radiographically measurable disease per the Lugano Response Criteria.
* Has provided a newly obtained core or excisional biopsy or archival tissue of a tumor lesion not previously irradiated.
* If human immunodeficiency virus (HIV)-positive, has well-controlled HIV on antiretroviral therapy (ART).
* If hepatitis B surface antigen (HBsAg)-positive, has undetectable hepatitis B virus (HBV) viral load and has received HBV antiviral therapy for at least 4 weeks and will continue it.
* If history of hepatitis C virus (HCV) infection, has undetectable HCV viral load.

Exclusion Criteria:

* Has received prior systemic anticancer therapy or radiotherapy for FL.
* Has follicular large B-cell lymphoma or any other subtype of FL other than classical FL.
* Has FL that has transformed into a more aggressive type of lymphoma.
* History or presence of clinically relevant central nervous system (CNS) diseases.
* Has history of serious cardiovascular and cerebrovascular diseases.
* Is HIV-infected with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease.
* Has received a live or live-attenuated vaccine within 30 days before the first dose of study intervention.
* Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy.
* Has a known additional malignancy that is progressing or has required active treatment within the past 3 years.
* Has known active CNS lymphoma or involvement.
* Has an active autoimmune disease that has required systemic treatment in the past 2 years.
* Has active infection requiring systemic therapy.
* Has chronic liver disease, including liver cirrhosis of Child-Pugh class B or C.
* Has not adequately recovered from major surgery or has ongoing surgical complications.