- For the Phase I portion of the study, patients must have pathologically confirmed diagnosis of low-grade or follicular, CD20-positive, B-cell, non-Hodgkin's lymphoma that has relapsed or is refractory. For the Phase II portion of the study, patients must have a pathologically confirmed diagnosis of low-grade or follicular, CD20-positive, B-cell, non-Hodgkin's lymphoma (Follicular, predominantly small cleaved or follicular, mixed small cleaved and large cell, International Working Formulation classification B or C or REAL classification follicular center grade 1,2) that has relapsed or is refractory.