A Possible Cure for Refractory DLBCL: CARs Are Headed in the Right Direction
Authors: Julio C. Chavez, Frederick L. Locke
Journal: Molecular Therapy (2017)

Significant excitement has been generated by the ability of adoptively transferred chimeric antigen receptor (CAR) T cells to produce complete responses for B cell malignancies. The CAR, inserted into T cells via a viral vector, is an artificial antigen receptor comprising an antibody’s antigen-receptor domain fused to T cell activation and co-stimulatory signaling domains. Individual institutions have reported response rates of 50%–90% in refractory B cell malignancies treated with anti-CD19 CAR T cells, leading to multicenter trials. The impressive response rates in patients refractory to chemotherapy were replicated in these pivotal trials, suggesting imminent US Food and Drug Administration (FDA) approval for pediatric acute lymphoblastic leukemia (ALL) and diffuse large B cell lymphoma (DLBCL). While objective response rates and complete response rates are high, there is a paucity of long-term safety and efficacy data for patients treated with second generation CD19-targeted CAR T cells, in particular for adult lymphoma patients. In this issue of Molecular Therapy, Kochenderfer and colleagues1Kochenderfer J.N. Somerville R.P.T. Lu T. Yang J.C. Sherry R.M. Feldman S.A. McIntyre L. Bot A. Rossi J. Lam N. Rosenberg S.A. Long-duration complete remissions of diffuse large B cell lymphoma after anti-CD19 chimeric antigen receptor T cell therapy.Mol Ther. 2017; 25 (this issue): 2245-2253Google Scholar provide long-term follow-up for seven patients with chemotherapy refractory aggressive B cell lymphoma, including DLBCL, primary mediastinal B cell lymphoma (PMBCL), transformed follicular lymphoma (TFL), and DLBCL/Richter’s synfrome. This report is important for several reasons. First, this provides the longest follow-up to date for CAR T cell-treated DLBCL survivors. Several patients remain in remission 4 years after a single infusion of CAR T cells. DLCBL is the most common aggressive lymphoma and is considered a curable disease with combination chemotherapy containing an anthracycline and anti-CD20 monoclonal antibody. However, about 30%–40% of patients will relapse or remain refractory and eventually succumb to their disease.2Coiffier B. Thieblemont C. Van Den Neste E. Lepeu G. Plantier I. Castaigne S. Lefort S. Marit G. Macro M. Sebban C. et al.Long-term outcome of patients in the LNH-98.5 trial, the first randomized study comparing rituximab-CHOP to standard CHOP chemotherapy in DLBCL patients: a study by the Groupe d’Etudes des Lymphomes de l’Adulte.Blood. 2010; 116: 2040-2045Google Scholar Although some patients can still be salvaged with autologous stem cell transplant (ASCT), those with early relapse, primary refractory disease, or progression after ASCT have a dismal prognosis and a standard-of-care treatment is not available.3Crump M. Neelapu S.S. Farooq U. Van Den Neste E. Kuruvilla J. Ahmed M.A. Link B.K. Hay A.E. Cerhan J.R. Zhu L. et al.Outcomes in refractory aggressive diffuse large b-cell lymphoma (DLBCL): Results from the international SCHOLAR-1 study.J Clin Oncol. 2016; 34 (7516–7516)Google Scholar Earlier reports from the National Cancer Institute (NCI), and other groups, demonstrated that second generation anti-CD19 CAR T cells can safely put refractory DLCBL into remission.4Kochenderfer J.N. Wilson W.H. Janik J.E. Dudley M.E. Stetler-Stevenson M. Feldman S.A. Maric I. Raffeld M. Nathan D.A. Lanier B.J. et al.Eradication of B-lineage cells and regression of lymphoma in a patient treated with autologous T cells genetically engineered to recognize CD19.Blood. 2010; 116: 4099-4102Google Scholar, 5Turtle C.J. Hanafi L.A. Berger C. Hudecek M. Pender B. Robinson E. Hawkins R. Chaney C. Cherian S. Chen X. et al.Immunotherapy of non-Hodgkin’s lymphoma with a defined ratio of CD8+ and CD4+ CD19-specific chimeric antigen receptor-modified T cells.Sci. Transl. Med. 2016; 8: 355ra116Google Scholar These results were replicated in the multicenter phase I portion of the Zuma-1 trial testing KTE-C19 (now called axicabtagene ciloleucel, or axi-cel for short), the licensed anti-CD19 CAR T cell product manufactured with the same CAR T cell construct created at the NCI.6Locke F.L. Neelapu S.S. Bartlett N.L. Siddiqi T. Chavez J.C. Hosing C.M. Ghobadi A. Budde L.E. Bot A. Rossi J.M. et al.Phase 1 Results of ZUMA-1: A Multicenter Study of KTE-C19 Anti-CD19 CAR T Cell Therapy in Refractory Aggressive Lymphoma.Mol. Ther. 2017; 25: 285-295Google Scholar A better understanding of the efficacy of the therapy for aggressive lymphomas came from the primary analysis of the phase 2 portion of the Zuma-1 trial, which included DLBCL, PMBCL, and TFL patients.7Locke F.L. Neelapu S.S. Bartlett N.L. Lekakis L.J. Miklos D. Jacobson C.A. Braunschweig I. Oluwole O. Siddiqi T. Lin Y. et al.Abstract CT019: Primary results from ZUMA-1: a pivotal trial of axicabtagene ciloleucel (axicel; KTE-C19) in patients with refractory aggressive non-Hodgkin lymphoma (NHL).Cancer Res. 2017; 77 (CT019–CT019)Google Scholar The objective response rate was 82% and the complete response rate was 54%, comparing very favorably to historical controls of 26% and 8%, respectively.3Crump M. Neelapu S.S. Farooq U. Van Den Neste E. Kuruvilla J. Ahmed M.A. Link B.K. Hay A.E. Cerhan J.R. Zhu L. et al.Outcomes in refractory aggressive diffuse large b-cell lymphoma (DLBCL): Results from the international SCHOLAR-1 study.J Clin Oncol. 2016; 34 (7516–7516)Google Scholar Importantly, the 6-month overall survival was 80% as compared to 55% in SCHOLAR-1, a >600 patient metanalysis of prospectively collected data in a similar set of patients, suggesting the therapy could be positively impacting survival. The results presented by Kochenderfer and colleagues1Kochenderfer J.N. Somerville R.P.T. Lu T. Yang J.C. Sherry R.M. Feldman S.A. McIntyre L. Bot A. Rossi J. Lam N. Rosenberg S.A. Long-duration complete remissions of diffuse large B cell lymphoma after anti-CD19 chimeric antigen receptor T cell therapy.Mol Ther. 2017; 25 (this issue): 2245-2253Google Scholar in this issue indicate that responders have an opportunity for durable and long-lasting disease-free survival, lasting at least 4 years. DLBCL is curable with chemotherapy; therefore, eradication of the cancer with cellular immunotherapy is theoretically possible. Notably, these patients were not consolidated with allogeneic or autologous hematopoietic stem cell transplant. Only continued follow-up will determine whether aggressive B cell lymphoma could relapse after successful CAR T cell therapy. Second, this report demonstrates that recovery of normal B cells can occur with continued remission following CAR T cell therapy for lymphoma. The presence of polyclonal normal CD19+ B cells indicates that functional CAR T cells are no longer present. In order to eradicate B cell malignancy, functional CAR T cells must proliferate and at least transiently persist in vivo. The co-stimulatory signaling molecule (CD28 versus 4-1BB) and phenotype of the CAR T cell product (naive/central memory versus effector) may each impart different persistence kinetics. Alternatively, the duration of persistence required for cure may depend on the disease (lymphoma versus leukemia). Second-generation CAR constructs containing a CD28 costimulatory molecule have significantly increased in vivo persistence as compared to first-generation CARs lacking a co-stimulatory molecule.8Savoldo B. Ramos C.A. Liu E. Mims M.P. Keating M.J. Carrum G. Kamble R.T. Bollard C.M. Gee A.P. Mei Z. et al.CD28 costimulation improves expansion and persistence of chimeric antigen receptor-modified T cells in lymphoma patients.J. Clin. Invest. 2011; 121: 1822-1826Google Scholar In DLBCL patients treated with a 4-1BB-containing CAR, early B cell recovery was associated with an immune response against the murine single-chain variable fragment component of the CAR, which was abrogated by the addition of the immunosuppressive fludarabine to the conditioning regimen.5Turtle C.J. Hanafi L.A. Berger C. Hudecek M. Pender B. Robinson E. Hawkins R. Chaney C. Cherian S. Chen X. et al.Immunotherapy of non-Hodgkin’s lymphoma with a defined ratio of CD8+ and CD4+ CD19-specific chimeric antigen receptor-modified T cells.Sci. Transl. Med. 2016; 8: 355ra116Google Scholar CAR T cell products containing more naive/central memory T cells at the start of manufacture and those containing more naive/central memory T cells at the end of manufacture have increased capacity for in vivo expansion.7Locke F.L. Neelapu S.S. Bartlett N.L. Lekakis L.J. Miklos D. Jacobson C.A. Braunschweig I. Oluwole O. Siddiqi T. Lin Y. et al.Abstract CT019: Primary results from ZUMA-1: a pivotal trial of axicabtagene ciloleucel (axicel; KTE-C19) in patients with refractory aggressive non-Hodgkin lymphoma (NHL).Cancer Res. 2017; 77 (CT019–CT019)Google Scholar, 9Sommermeyer D. Hudecek M. Kosasih P.L. Gogishvili T. Maloney D.G. Turtle C.J. Riddell S.R. Chimeric antigen receptor-modified T cells derived from defined CD8+ and CD4+ subsets confer superior antitumor reactivity in vivo.Leukemia. 2016; 30: 492-500Google Scholar In this issue, Kochenderfer et al.1Kochenderfer J.N. Somerville R.P.T. Lu T. Yang J.C. Sherry R.M. Feldman S.A. McIntyre L. Bot A. Rossi J. Lam N. Rosenberg S.A. Long-duration complete remissions of diffuse large B cell lymphoma after anti-CD19 chimeric antigen receptor T cell therapy.Mol Ther. 2017; 25 (this issue): 2245-2253Google Scholar demonstrate that normal CD19+ polyclonal B cell recovery occurred in 3 of 4 long-term responders between 10 and 30 months after CAR T cell therapy. Whether earlier loss of functional CD3/CD28 CAR T cells is associated with relapse is uncertain. B cell recovery as it relates to remission rate and duration of remissions must be studied in a larger dataset of patients with attention to the CAR T cell product phenotype and disease specific factors, such as disease burden. Finally, in this small series of patients, the incidence of severe late infections was low. These findings suggest that prolonged hypo-gammaglobulinemia and B cell depletion after anti-CD19 CAR T cell therapy may not be associated with high rates of severe morbidity. Alternate standard-of-care therapies, such as rituximab and autologous stem cell transplantation for DLBCL, can also cause profound B cell depletion and hypogammaglobulinemia.10Lim S.H. Esler W.V. Zhang Y. Zhang J. Periman P.O. Burris C. Townsend M. B-cell depletion for 2 years after autologous stem cell transplant for NHL induces prolonged hypogammaglobulinemia beyond the rituximab maintenance period.Leuk. Lymphoma. 2008; 49: 152-153Google Scholar Oncologists are aware of the infectious risks and how to manage such patients, which includes careful patient education about handwashing and other infectious pathogen avoidance measures as well as immunoglobulin replacement if necessary. While clinicians and patients may be relieved, the sample size is too small and the patients’ immune recovery was too variable to discount the risk of sudden and severe life-threatening infections late after CAR T cell therapy. Normal B cell recovery was reported, and there was variable return to normal levels of immunoglobulin G (IgG), IgM, and IgA in the long-term survivors.1Kochenderfer J.N. Somerville R.P.T. Lu T. Yang J.C. Sherry R.M. Feldman S.A. McIntyre L. Bot A. Rossi J. Lam N. Rosenberg S.A. Long-duration complete remissions of diffuse large B cell lymphoma after anti-CD19 chimeric antigen receptor T cell therapy.Mol Ther. 2017; 25 (this issue): 2245-2253Google Scholar Risks for infection are also related to the immune recovery of other immune cell subsets. Long-term data on repopulation of non-CAR expressing poly-specific CD4 and CD8 T cells, natural killer (NK) cells, regulatory T cells (Tregs), and myeloid-derived suppressor cells (MDSCs) is needed. There remains little known about the long-term non-relapse morbidity and mortality of CAR T cell therapy highlighting the importance of long-term data collection after FDA approval. A likely mechanism for this is the Center for International Blood and Marrow Transplant Research (CIBMTR), which already collects data for hematopoietic stem cell transplants across hundreds of centers. Despite the important information in this report, there is much we still do not know about anti-CD19 CAR T cell therapy for DLBCL. Longer-term follow-up in a larger group of patients is needed to assess long-term disease-free survival, the expected and necessary duration of functional CAR T cell persistence, and the risks for long-term morbidity and mortality. A major unanswered question surrounds the mechanisms of resistance and relapse. Loss of the CAR binding CD19 epitope may occur; however, it is possible the causes for its loss differ from those described in highly undifferentiated ALL.11Gardner R. Wu D. Cherian S. Fang M. Hanafi L.A. Finney O. Smithers H. Jensen M.C. Riddell S.R. Maloney D.G. Turtle C.J. Acquisition of a CD19-negative myeloid phenotype allows immune escape of MLL-rearranged B-ALL from CD19 CAR-T-cell therapy.Blood. 2016; 127: 2406-2410Google Scholar, 12Sotillo E. Barrett D.M. Black K.L. Bagashev A. Oldridge D. Wu G. Sussman R. Lanauze C. Ruella M. Gazzara M.R. et al.Convergence of Acquired Mutations and Alternative Splicing of CD19 Enables Resistance to CART-19 Immunotherapy.Cancer Discov. 2015; 5: 1282-1295Google Scholar Immune-negative regulation also plays a role. PD-1 is upregulated on CAR T cells upon activation.13Cherkassky L. Morello A. Villena-Vargas J. Feng Y. Dimitrov D.S. Jones D.R. Sadelain M. Adusumilli P.S. Human CAR T cells with cell-intrinsic PD-1 checkpoint blockade resist tumor-mediated inhibition.J. Clin. Invest. 2016; 126: 3130-3144Google Scholar CTLA4, PDL1, and LAG3 are upregulated in the tumor microenvironment of human DLBCL shortly after CAR T cell infusion.14Galon J. Rossi J. Turcan S. Danan C. Locke F.L. Neelapu S.S. Miklos D.V. Bartlett N.L. Jacobson C.A. Braunschweig I. et al.Characterization of anti-CD19 chimeric antigen receptor (CAR) T cell-mediated tumor microenvironment immune gene profile in a multicenter trial (ZUMA-1) with axicabtagene ciloleucel (axi-cel, KTE-C19).J Clin Oncol. 2017; 35 (3025–3025)Google Scholar Trials combining checkpoint blockade with CAR T cell therapy are ongoing (NCT02926833). In lymphoma patients, the peak CAR T cell expansion and area under the curve over the first month correlate with remissions.7Locke F.L. Neelapu S.S. Bartlett N.L. Lekakis L.J. Miklos D. Jacobson C.A. Braunschweig I. Oluwole O. Siddiqi T. Lin Y. et al.Abstract CT019: Primary results from ZUMA-1: a pivotal trial of axicabtagene ciloleucel (axicel; KTE-C19) in patients with refractory aggressive non-Hodgkin lymphoma (NHL).Cancer Res. 2017; 77 (CT019–CT019)Google Scholar Unfortunately, expansion has also been shown to correlate with toxicities, suggesting that simply amplifying expansion may increase efficacy at the expense of greater toxicity. Abrogation of the acute toxicities of CAR T cells is a major focus for translational investigation. In summary, the findings reported by Kochenderfer et al.1Kochenderfer J.N. Somerville R.P.T. Lu T. Yang J.C. Sherry R.M. Feldman S.A. McIntyre L. Bot A. Rossi J. Lam N. Rosenberg S.A. Long-duration complete remissions of diffuse large B cell lymphoma after anti-CD19 chimeric antigen receptor T cell therapy.Mol Ther. 2017; 25 (this issue): 2245-2253Google Scholar tell us that CD3zeta/CD28 anti-CD19 CAR T cells can lead to long-term remissions in DLBCL and can be accompanied by recovery of normal polyclonal CD19+ B cells. This information is critical when considering the risk/benefit ratio of this new therapy. As FDA approval for CAR T cell therapy is expected soon, clinicians practicing cellular immunotherapy and referring oncologists must understand these findings to help guide appropriate therapy for relapsed and refractory DLBCL. Randomized phase 3 trials comparing CAR T cell therapy to standard salvage chemotherapy and autologous transplant is warranted. Early referral to centers with CAR T cell experience is paramount. There is still much-needed data in regard to CAR T cell persistence and resistance, long-term morbidity of the therapy, and whether it truly can cure refractory DLBCL. Long-Duration Complete Remissions of Diffuse Large B Cell Lymphoma after Anti-CD19 Chimeric Antigen Receptor T Cell TherapyKochenderfer et al.Molecular TherapyJuly 14, 2017In BriefFive of seven patients receiving anti-CD19 chimeric antigen receptor (CAR) T cells obtained complete remissions. Four of the five CRs had long-term durability with durations of remissions ranging from 38 to 56 months. Remissions persisted despite recovery of normal B cells in three of the four patients with long-term remissions. Full-Text PDF Open Archive