CD79b-19 CAR T Cells in Non-Hodgkin Lymphoma

This research study involves the study of CD79b-19 CAR T cells for treating people with relapsed/refractory Non-Hodgkin Lymphoma and to understand the side effects when treated with CD79b-19 CAR T cells. This research study involves the study drugs: * CD79b-19 CAR T cells * Fludarabine and Cyclophosphamide: Standardly used chemotherapy drugs as part of lymphodepleting process

This is a two-part, non-randomized, open label, single-site Phase 1 study of CD79b-19 CAR T cells as a treatment for relapsed/refractory Non-Hodgkin Lymphoma. This study consists of 2 parts: * Part A (Dose Escalation): The investigators are looking to find the highest dose of the study intervention that can be administered safely without severe or unmanageable side effects, not everyone who participates in this research study will receive the same dose of the study intervention. The dose given will depend on the number of participants who have been enrolled prior and how well the dose was tolerated. Once determined, this highest dose will then be used in the dose expansion part of the study. * Part B (Expansion Cohort): Participants will be treated at the respective dose as determined during Part A (Dose Escalation). CD79b-19 CAR T cells is an investigational treatment that uses a person's own immune cells, called T cells, to try to kill their cancerous cells. T cells fight infections and can also kill cancer cells in some cases. The U.S. Food and Drug Administration (FDA) has not approved CD79b-19 CAR T cells as a treatment for any disease. This is the first time that CD79b-19 CAR T cells will be given to humans. The research study procedures include screening for eligibility and study treatment including evaluations and follow up visits. Participants will receive one infusion of the study treatment and will be followed for up to 2 years. It is expected that about 24 people will take part in this research study.