Treatment of patients with relapsed or refractory CD19+ lymphoid disease with T lymphocytes transduced by RV-SFG.CD19.CD28.4-1BBzeta retroviral vector: a unicentre phase I/II clinical trial protocol

Abstract

Introduction: Chimeric antigen receptor (CAR) T cells spark hope for patients with CD19+ B cell neoplasia, including relapsed or refractory (r/r) acute lymphoblastic leukaemia (ALL) or r/r non-Hodgkin's lymphoma (NHL). Published studies have mostly used second-generation CARs with 4-1BB or CD28 as costimulatory domains. Preclinical results of third-generation CARs incorporating both elements have shown superiority concerning longevity and proliferation. The University Hospital of Heidelberg is the first institution to run an investigator-initiated trial (IIT) CAR T cell trial (Heidelberg Chimeric Antigen Receptor T cell Trial number 1 [HD-CAR-1]) in Germany with third-generation CD19-directed CAR T cells.

Methods and analysis: Adult patients with r/r ALL (stratum I), r/r NHL including chronic lymphocytic leukaemia, diffuse large B-cell lymphoma, follicular lymphoma or mantle cell lymphoma (stratum II) as well as paediatric patients with r/r ALL (stratum III) will be treated with autologous T-lymphocytes transduced by third-generation RV-SFG.CD19.CD28.4-1BB zeta retroviral vector (CD19.CAR T cells). The main purpose of this study is to evaluate safety and feasibility of escalating CD19.CAR T cell doses (1-20×10⁶ transduced cells/m²) after lymphodepletion with fludarabine (flu) and cyclophosphamide (cyc). Patients will be monitored for cytokine release syndrome (CRS), neurotoxicity, i.e. CAR-T-cell-related encephalopathy syndrome (CRES) and/or other toxicities (primary objectives). Secondary objectives include evaluation of in vivo function and survival of CD19.CAR T cells and assessment of CD19.CAR T cell antitumour efficacy.HD-CAR-1 as a prospective, monocentric trial aims to make CAR T cell therapy accessible to patients in Europe. Currently, HD-CAR-1 is the first and only CAR T cell IIT in Germany. A third-generation Good Manufacturing Practice (GMP) grade retroviral vector, a broad spectrum of NHL, treatment of paediatric and adult ALL patients and inclusion of patients even after allogeneic stem cell transplantation (alloSCT) make this trial unique.

Ethics and dissemination: Ethical approval and approvals from the local and federal competent authorities were granted. Trial results will be reported via peer-reviewed journals and presented at conferences and scientific meetings.

Trial registration number: Eudra CT 2016-004808-60; NCT03676504; Pre-results.

Keywords: 4-1bb (cd137), Cd28 Costimulatory Domains; CD19 CAR T cells; refractory Or relapsed leukaemia and lymphoma; third-generation car T cells.

Figure 1

HD-CAR-1 treatment strata. *Dose escalation design of HD-CAR-1 is performed according to a classical 3+3+4 design. Stratum I and II (adult ALL and CLL/NHL) are recruited independently. Occurrence of dose-limiting events in one of these strata does not affect recruitment of the other one. The first cohort of three patients in stratum I and stratum II is treated with CD19.CAR T cells at dose level (D) 1. Between treatments of individual patients, a waiting period of at least 28 days is mandatory. If any of the first three patients displays DLT, three more patients are enrolled at D1. If less than three DLTs occur in this group of six patients, the study continues to D2. The same scheme is applied to progress towards D3. Initiation of stratum III (children and adolescents with r/r ALL) is performed after completion of D1 in stratum I or II without evidence of DLT in the first three patients, or with ≤2 DLT in the first six patients. If more than two patients display DLT at D1, D2 or D3, the DMC will be advised. An interim evaluation by the DMC is mandatory after completion of D1 and D2. ALL, acute lymphoblastic leukaemia; CLL, chronic lymphocytic leukaemia; D, dose level; DLBCL, diffuse large B cell lymphoma; DLT, dose-limiting toxicity; DMC, Data Monitoring Committee; FL, follicular lymphoma; HD-CAR-1, Heidelberg Chimeric Antigen Receptor T cell Trial number 1; MCL, mantle cell lymphoma; NHL, non-Hodgkin’s lymphoma.

Figure 2

Structure of the HD-CAR-1 CAR. (A) Structure of the third-generation CAR construct used in the HD-CAR-1 trial. The CAR is composed of an extracellular antigen-specific scFv molecule derived from the IgG2a mouse monoclonal antibody FMC63. The scFv is attached via a flexible hinge region from the human IgG1-CH₂CH₃ domain to the CD28-derived transmembrane. This, in turn, is attached to the cytoplasmic receptor portion. The intracellular signalling domain originates from the stimulatory CD3ζ-chain of a T cell receptor. In the third-generation HD-CAR-1 construct, costimulation is mediated by the CD28 and 4-1BB domains. (B) Linear representation of RV-SFG.CD19.CD28.4-1BBzeta. HD-CAR-1, Heidelberg Chimeric Antigen Receptor T cell Trial number 1; scFv, single-chain variable fragment.

Figure 3

HD-CAR-1 clinical trial: general time schedule. After inclusion, patients undergo leukapheresis followed by CAR T cell production. After clearance of QC of the CD19.CAR T cell product, patients receive a preconditioning therapy consisting of fludarabine (flu) 30 mg/m²/day and cyclophosphamide (cy) 500 mg/m²/day (day −4 to day −2) followed by a rest day on day −1. Patients receive CD19.CAR T cells intravenously on treatment day 0. CD19.CAR T cell infusion is followed by at least 14 days of in-patient observation. This period is followed by out-patient monitoring with EOT on day 28 and EOS on day 90 after CD19.CAR T cell administration. EOS, end-of-study; EOT, end-of-treatment; HD-CAR-1, Heidelberg Chimeric Antigen Receptor T cell Trial number 1; MRD, minimal residual disease; QC, quality control.