Study of ME-401 in Subjects With Relapsed or Refractory Indolent B-cell Non-Hodgkin's Lymphoma

Inclusion Criteria: \[Phase 1 study (DLT evaluation)\] * Patients aged 20 years or older at the submission of the written informed consent form * Patients with relapsed or refractory B-cell NHL * Patients who have not undergone phosphatidylinositol 3-kinase inhibitor (PI3K) to date. * Patients who have undergone Bruton's tyrosine kinase (BTK) inhibitors and have had no exacerbation during the use of BTK inhibitors. * Patients with ECOG PS 0 or 1. Exclusion Criteria: \[Phase 1 study (DLT evaluation)\] * Patients who underwent any major surgical treatment within 4 weeks prior to the initiation of the investigational product. * Patients with poorly controlled diseases. The followings are the examples but the diseases will not be limited to those. * Patients in whom any of HBV antigen/antibody, HCV antibody, HIV antibody or HTLV-1 antibody will be positive at screening test. * Patients with active interstitial lung disease or a history thereof. * Patients who have received the investigational products other than ME-401, systemic chemotherapy or radiotherapy within 4 weeks prior to the initiation of ME-401.