Mass General - Division of Clinical Research

MEI-401 Alone: - Diagnosis of relapsed/refractory CLL and/or relapsed/refractory SLL or FL - No prior therapy with PI3Kd inhibitors - No prior therapy with Bruton tyrosine kinase (BTK) inhibitors unless the subject was intolerant of BTK therapy or subject had disease progression - Subjects with CLL/SLL must have prior treatment with BTK inhibitor and must have had progression or recurrence while on treatment of within 12 mos from BTK treatment - Subject must have failed at least 1 prior systemic therapy - QT-interval corrected according to Fridericia's formula (QTcF) ≤ 450 milliseconds (ms) - Left ventricular ejection fraction > 50% - For subjects, except those with CLL, must have at least one bi-dimensionally measurable nodal lesion >1.5 cm, as defined by Lugano Classification - Willingness to participate in collection of pharmacokinetic samples - A negative serum pregnancy test within 14 days of study Day 0, for females of childbearing potential Inclusion Criteria ME-401 in Combination with Rituximab - Diagnosis of relapsed/refractory CLL SLL or FL, MZL, DLBCL and high-grade B-cell lymphoma. Subjects must meet the following criteria for relapsed or refractory disease: - No prior therapy with PI3Kδ inhibitors - No prior therapy with Bruton tyrosine kinase (BTK) inhibitors unless the subject was intolerant of BTK therapy or subject had disease progression - Subjects with CLL, SLL, FL, and MZL must have a failure of at least 1 prior systemic therapy and be considered by the investigator a candidate for therapy with a rituximab-based regimen; subjects with DLBCL and high-grade B-cell lymphoma must have a failure of at least 2 prior therapies. - QT-interval corrected according to Fridericia's formula (QTcF) ≤450 milliseconds (ms) - Left ventricular ejection fraction > 50% - For subjects, except those with CLL, must have at least one bi-dimensionally measurable nodal lesion >1.5 cm, as defined by Lugano Classification - Willingness to participate in collection of pharmacokinetic samples - A negative serum pregnancy test within 14 days of study Day 0 for females of childbearing potential Inclusion Criteria ME-401 in Combination with Zanubrutinib - Diagnosis of relapsed/refractory CLL or histologically-confirmed relapsed/refractory SLL or FL, MZL, MCL, DLBCL NOS (germinal center B-cell type or activated B-cell type) - No prior therapy with PI3Kδ inhibitors - No prior therapy with BTK inhibitors - Subjects with CLL, SLL, FL, MCL, and MZL must have a failure of at least 1 prior systemic therapy, require treatment in the opinion of the investigator, and be considered by the investigator a candidate for therapy subjects with DLBCL and high-grade B-cell lymphoma must have a failure of at least 2 prior therapies - For subjects with SLL, FL, MZL, MCL, DLBCL: At least one bi dimensionally measurable nodal lesion > 1.5 cm in its longest diameter by CT scan or MRI - QT-interval corrected according to Fridericia's formula (QTcF) ≤ 450 milliseconds (msec) - Left ventricular ejection fraction > 50% as measured by echocardiogram or multigated acquisition (MUGA) scan - Willingness to participate in collection of pharmacokinetic samples - For females of childbearing potential, a negative serum pregnancy test within 14 days of study Day 0

• Known histological transformation from CLL to an aggressive lymphoma - Uncontrolled autoimmune hemolytic anemia or immune thrombocytopenia - Subjects who have tested positive for hepatitis B surface antigen and/or hepatitis B core antibody - Positive for hepatitis C virus antibody (HCV Ab) or human immunodeficiency virus (HIV) antibody - Ongoing drug-induced pneumonitis - History of clinically significant cardiovascular abnormalities - History of severe bleeding disorders (ME-401 plus zanubrutinib arm only) - Known central nervous system (CNS) hemorrhage or stroke within 6 months prior to start of study drugs (ME-401 plus zanubrutinib arm only)