Phase 1/2 Study of CD19 Chimeric Antigen Receptor T-cell (CD19 CAR-T; PL001) for Relapsed or Refractory B-cell Lymphoma

Inclusion Criteria: Screening 1: 1. Patient is ≥14 years of age, inclusive, at the time of signing the informed consent. 2. Histologically confirmed diagnosis of diffuse large B-cell lymphoma (DLBCL), primary mediastinal large B-cell lymphoma (PMLBCL), large B-cell lymphoma transformed from follicular lymphoma (FL), or grade 3a or 3b FL. 3. On-site documentation of CD19 on the dominant population of cancer cells. 4. Disease status should meet any one of the below: 1. Patients with previous autologous-hematopoietic stem cell transplantation (auto HSCT) have relapsed, progressive, or refractory disease (defined as having not achieved a CR) after transplantation regardless of lines of systemic therapy. 2. Patients without previous HSCT have relapsed, progressive, or refractory disease (defined as having not achieved a CR) after at least 2 lines of systemic therapy, including anti-CD20 antibody and anthracycline. 5. Have no available effective systemic therapy as judged by the Investigator. 6. At least one measurable non-CNS (central nervous system) lesion based on Lugano classification for lymphoma. 7. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2. 8. Life expectancy of at least 3 months. 9. Patient is male or female. 10. A male patient must agree to use a highly effective contraception as detailed in Section 10.4 (Appendix 4) during the treatment period and for at least 2 years after the dose of PL001 and refrain from donating sperm during this period. Female Patients: 11. A female patient is eligible to participate if she is not pregnant (Section 10.4; Appendix 4), not breastfeeding, and at least one of the following conditions applies: • Not a woman of childbearing potential (WOCBP) as defined in Section 10.4 (Appendix 4). OR • A WOCBP who agrees to follow the contraceptive guidance in Section 10.4 (Appendix 4) during the treatment period and for at least 2 years after the dose of PL001 and refrain from donating ova during this period. 12. Patient/patient's parent/legal guardian is capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. Screening 2: 1. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2. 2. CAR-T is successfully manufactured and ready for use, from cells harvested by non mobilized leukapheresis. 3. WOCBP who have a negative serum pregnancy test at Screening 2. Exclusion Criteria: Screening 1: 1. Chronic lymphocytic leukemia with Richter's transformation. 2. Primary CNS lymphoma. (Non-primary CNS lymphoma with CNS involvement is eligible). 3. Primary intra-ocular lymphoma. 4. Prior CD19 targeted therapy, such as CAR-T, Bi-specific T-cell engagers (BiTE), or monoclonal antibody. 5. History of cancers (includes myelodysplastic syndrome) other than non-melanoma skin cancer or carcinoma in situ (e.g., cervix, bladder, breast) unless disease-free without active treatment for at least 3 years. 6. History of allogeneic HSCT. 7. History of autologous HSCT within 3 months prior to consent. 8. Received any investigational product within 4 weeks prior to consent. 9. Systemic anticancer therapy within 3 weeks prior to apheresis. 10. Long-term use of systemic corticosteroids, defined as daily use \>10 mg of prednisolone or equivalent, within 2 weeks prior to leukapheresis. Exception examples: * Nasal, ophthalmic, inhaled, intra-articular, and topical steroid preparation. * Short term systemic steroid for drug, contrast, or blood transfusion allergic reaction management. * Low dose maintenance steroid therapy for other conditions (e.g., asthma). 11. Use of long-acting and short-acting myeloid growth factor within 2 weeks, 5 days prior to leukapheresis, respectively. 12. Received anti-thymocyte globulin within 4 weeks prior to consent. 13. Intrathecal chemotherapy within 1 week prior to leukapheresis. 14. Inadequate major organ functions at Screening, which were defined as any of below: 1. absolute neutrophil count (ANC) \<500/µL 2. Absolute lymphocyte count (ALC) \<300/µL, excluding leukemic cells. 3. Hemoglobin (Hb) \<8.0 g/dL 4. Platelet count \<75,000/µL without transfusion support within 3 days 5. e. Baseline O2 saturation \<92% by pulse oximetry at room air 6. Significant CNS diseases such as dementia, major stroke, seizure while under antiepileptic drug 7. Aspartate aminotransferase (AST) \>5 × upper limit of normal (ULN) and alanine aminotransferase (ALT) \>5 × ULN, or total bilirubin \>2 × ULN (except for constitutional jaundice) 8. Serum creatinine \> 1.5 × ULN and estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73 m², as calculated by the Cockcroft-Gault formula. 9. Significant cardiac disease including but not limited to: left ventricular ejection fraction (LVEF) \<50%, QTc(the corrected QT interval) \> 480 msec based on Fredericia's formula, clinically significant arrhythmias, history of myocardial infarction or unstable angina within 3 months prior to consent. 15. Active hepatitis B virus (HBV) infection defined as detectable HBV DNA (Patients with positive anti-hepatitis B core antibody \[HBcAb\] must consent to regular monitoring of HBV DNA, and anti-HBV prophylaxis with oral anti-viral agent (such as entecavir) is mandatory until End-of-Study visit \[Visit 15\].) 16. Active hepatitis C virus (HCV) infection defined as positive anti- HCV antibody plus detectable HCV RNA. 17. Positive for human immunodeficiency virus (HIV) or human T-cell lymphotropic virus (HTLV) infection. 18. Uncontrolled acute life-threatening bacterial, viral, or fungal infection (e.g., the need for intravenous therapeutic antibiotics, blood culture positive ≤72 hours prior to apheresis). 21\. Any medical conditions which might compromise the patient's safety from leukapheresis, lymphodepletion chemotherapy, or CAR-T therapy and anticipated AEs, according to the Investigator's evaluation. 22.Patients with insufficient leukapheresis cells. Screening 2: 1. Inadequate major organ functions at Screening which were defined as any of below: 1. ANC \<500/µL 2. Hb \<8.0 g/dL 3. Platelet count \<50,000/µL, without transfusion support within 3 days 4. Baseline O2 saturation \<92% by pulse oximetry on room air 5. AST \>5 × ULN and ALT\>5 × ULN, or total bilirubin \>2 × ULN (except for constitutional jaundice) 6. Significant CNS diseases such as dementia, major stroke, seizure while under antiepileptic drug 7. Serum creatinine \> 1.5 × ULN and estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73 m², as calculated by the Cockcroft-Gault formula. 2. Long-term use of systemic corticosteroids, defined as daily use \>10 mg of prednisolone or equivalent. Exception examples: * Nasal, ophthalmic, inhaled, intra-articular, and topical steroid preparation. * Short term systemic steroid for drug, contrast, or blood transfusion allergic reaction management. * Low dose maintenance steroid therapy for other conditions (e.g., asthma). 3. Use of long-acting and short-acting myeloid growth factor within 12 days, 2 days prior to lymphodepletion therapy, respectively. 4. Uncontrolled acute life-threatening bacterial, viral, or fungal infection (e.g. the need for intravenous therapeutic antibiotics, blood culture positive ≤72 hours prior to lymphodepletion). 5. Any medical condition which might compromise the patient's safety because of lymphodepletion chemotherapy or CAR-T therapy and anticipated AEs, according to the Investigator's opinion.