Venetoclax With Obinutuzumab and Magrolimab (VENOM) in Relapsed and Refractory Indolent B-cell Malignancies

Background: B-cell lymphoma is a cancer of certain white blood cells (called lymphocytes). These cells are found in lymph nodes. The cancer can cause enlargement of the lymph nodes leading to pain and discomfort. Swollen lymph nodes can also press on nearby organs such as liver and kidneys which can affect normal functioning of the organs. Researchers think that a new combination of drugs may be able to help. Objective: To find out if it is safe to give the combination of Magrolimab, Obinutuzumab and Venetoclax to people with B-cell lymphomas. Eligibility: Adults age 18 and older with an indolent B-cell lymphoma whose disease has returned or progressed after other treatment. Indolent B-cell lymphoma for this protocol is defined as having either follicular lymphoma, mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma or marginal zone lymphoma. Design: Participants will be screened under a separate protocol. Participants will have 28-day 'cycles' of treatment. They will take Venetoclax by mouth daily. They will get Obinutuzumab and Magrolimab by intravenous (IV) infusion. Treatment will last for about 8 months. They may be able to have more cycles of treatment if their cancer is responding well. Participants will have physical exams, medical histories, and medicine reviews. Data about how they function in their daily activities will be obtained. They will have blood and urine tests. They may have bone marrow tests. Participants will have imaging scans. These will include computed tomography (CT) and/or magnetic resonance imaging (MRI) scans and positron emission tomography (PET) scans. Participants may give a cheek swab or saliva sample. They may give tumor tissue and bone marrow samples. These samples may be used for gene testing. Participants will have a follow-up visit about 30 days after treatment ends. Then they will have visits every 3 months for the first 2 years, every 6 months for the next 3 years, and then yearly after that.

Background: * Indolent B-cell malignancies are associated with frequent disease relapse * Standard frontline therapy includes a monoclonal anti-cluster of differentiation 20 (CD20) antibody with or without chemotherapy; novel targeted therapies have changed the treatment landscape and are preferred therapy for some patients with high-risk molecular features * Targeted therapies given indefinitely add to drug resistance, treatment-emergent toxicities, and non-compliance * Cluster of differentiation 47 (CD47) is a rational target for indolent B-cell malignancies; CD47 expression is higher in tumor cells than normal B-cells, and blocking CD47 results in phagocytosis of tumor cells * Magrolimab is an anti-CD47 monoclonal antibody with activity in refractory indolent lymphomas when combined with rituximab (a first generation anti-CD20 monoclonal antibody) * Obinutuzumab is a novel anti-CD20 monoclonal antibody with enhanced binding to the Fc receptor that may improve antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis, when combined with magrolimab * We aim to test the safety and efficacy of venetoclax when added to the backbone of magrolimab and obinutuzumab in patients with relapsed or refractory indolent B-cell malignancies * Treatment duration will be response-adapted and time-limited in all patients Objective: -To determine the safety of the triplet combination of venetoclax, magrolimab and obinutuzumab in relapsed and refractory indolent B-cell malignancies Eligibility: * Follicular lymphoma (FL) (grades 1-2, or 3a), marginal zone lymphoma (MZL), mantle cell lymphoma (MCL) or chronic lymphocytic leukemia (CLL) with greater than or equal to 2 prior therapies, with at least one of those therapies containing an anti-CD20 monoclonal antibody * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * Adequate bone marrow and organ function Design: * Phase 1 study with expansion cohorts of up to 76 patients with relapsed or refractory FL, MZL, MCL or CLL * The safety profile of magrolimab, venetoclax, and obinutuzumab will first be determined in a dose-finding phase of up to 24 patients (6-12 patients with FL and 6-12 patients with MZL, MCL or CLL). Patients without dose-limiting toxicity (DLT) will receive an additional 5 cycles (total 6 cycles) of the triplet combination. * After dose-finding is completed, expansion cohorts of each histology will first receive magrolimab and obinutuzumab for 2 cycles in a window for translational research. After the window, venetoclax will be added and patients will receive 6 cycles (total 8 cycles) of the triplet combination. * Patients who achieve a complete response (CR) (after a total of 6 cycles of the triplet combination) will stop treatment and initiate active monitoring with radiologic imaging and assays for circulating tumor DNA (ctDNA); if these patients relapse, they can be retreated with 6 additional cycles. Patients who achieve partial response (PR) after 6 cycles of the triplet will continue for an additional 6 cycles; then, will initiate active monitoring.