Adoptive Transfer of Autologous CD25-Depleted, CD3/CD28-Costimulated T Cells After Cyclophosphamide - Fludarabine Chemotherapy in Patients with Low-Grade Follicular Lymphoma: Long-Term Follow up
Authors: Schuster Stephen J. , Aqui Nicole A. , Musher Benjamin , Levine Bruce L. , Andreadis Charalambos , Chong Elise A. , Nasta Sunita D. , Gordon Amanda , Cotte Julio , Zheng Zhaohui , Brennan Andrea L. , Veloso Elizabeth , June Carl H. 
Published: October 2019

Abstract
Abstract 1631

Introduction:
Fludarabine-based chemotherapy combinations are highly effective in patients with low-grade follicular lymphoma but cause severe and long-lasting immunosuppression related to depletion of normal T cells, especially CD4 T cells. Aside from increasing the risk of serious infections, this toxicity may limit the ability of the immune system to eliminate minimal residual disease. To determine whether adoptive transfer of autologous CD25-depleted, CD3/CD28-costimulated T cells expanded ex vivo (ACTC) improves immune reconstitution following cyclophosphamide - fludarabine chemotherapy, we conducted a phase I study in patients with relapsed/refractory follicular lymphoma.

Patients and Methods:
Eligible patients had previously treated, purine analog naïve, relapsed or refractory follicular lymphoma (grade 1 or 2). After leukapheresis, patients received 4 cycles of fludarabine (25 mg/m2) and cyclophosphamide (250 mg/m2) on days 1 – 3 of a 28 – 42 day cycle. Four weeks after last chemotherapy, responding patients [complete response (CR), complete response unconfirmed (CRu), and partial response (PR)] received escalating doses of ACTC prepared from autologous T cells collected prior to chemotherapy.

Results:
Fifteen patients were enrolled. Median age was 49 years (range: 32 – 68), median number of prior therapies was 2 (range: 1 – 3), and 14 patients (93%) were rituximab-refractory. Five patients were withdrawn from the study, 2 due to chemotherapy-related hematologic toxicity and 3 for progressive disease during chemotherapy. For 10 evaluable patients completing chemotherapy and ACTC infusion, 8 patients were in CR and 2 patients in PR at the time of ACTC infusion; 5 patients received 1 – 5 × 109 ACTC and 5 patients received 5 – 10 × 109 ACTC. There were no adverse events related to T cell infusions. Following chemotherapy and before ACTC infusion, median CD4 and CD8 counts were 91/μL (range: 15 –169) and 64/μL (range: 19 – 273), respectively; four weeks after ACTC, median CD4 and CD8 counts were 502/μL (range: 156 – 1053) and 509/μL (range: 158 – 1860). Median %CD4+FOXP3+ blood cells before chemotherapy was 15.8% (n = 8; range: 5.07 – 37.1); after chemotherapy / before ACTC, 21.4% (n = 7; range: 6.15 – 56.3); on day 60 after ACTC, 3.3% (n = 8; range: 1.5 – 20.4) (p = 0.01 for both pre ACTC and post ACTC comparisons). Before receiving chemotherapy and ACTC, all 10 patients were anergic to candida antigen by DTH skin testing; 60 days after ACTC, 5 patients developed a positive DTH response to candida antigen (p = 0.03). From the day of ACTC infusion, median progression-free survival (PFS) is 14.1 months. Most significantly, no patient relapsed or had progression of lymphoma after 14.1 months with follow-up from 16.5 – 101.5 months. In addition, PFS is significantly longer than time to progression from prior therapy (p = 0.01; see figure below). Overall survival after ACTC was 60% with median follow-up of 68 months.

Conclusions:
Adoptive transfer of ACTC after fludarabine - cyclophosphamide chemotherapy enhances recovery of CD4 and CD8 lymphocyte counts compared to historical observations, results in a relative reduction in peripheral blood FOXP3+ regulatory T cells, enhances recovery of lymphocyte function, and can result in prolonged remission. Our findings suggest that reversal of immunosuppression by adoptive transfer of autologous co-stimulated T-cells may significantly improve therapeutic outcome after cytotoxic therapy for patients with follicular lymphoma.

Disclosures:
Levine: US Patent: Financial interest due to intellectual property and patents in the field of cell and gene therapy. Conflict of interest is managed in accordance with University of Pennsylvania policy and oversight., Financial interest due to intellectual property and patents in the field of cell and gene therapy. Conflict of interest is managed in accordance with University of Pennsylvania policy and oversight. Patents & Royalties. June:Life Technologies / Invitrogen: cell culture technology patents owned by U.S. Government and licensed to Life Technology / Invitrogen, cell culture technology patents owned by U.S. Government and licensed to Life Technology / Invitrogen Patents & Royalties.