Adoptive Immunotherapy with Autologous CD25-Depleted and CD3/CD28-Costimulated T-Cells (ACTC) Enhances Numeric and Functional Lymphocyte Recovery after Cyclophosphamide - Fludarabine Chemotherapy in Patients with Low-Grade Follicular Lymphoma.

Fludarabine-based chemotherapy combinations are highly effective in patients (pts) with low-grade follicular lymphoma (FL), but cause severe and long-lasting immunosuppression due to depletion of normal 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. Adoptive immunotherapy using autologous CD25-depleted, CD3/CD28-costimulated T-cells expanded ex vivo (ACTC) may enhance immune reconstitution and improve disease control. We initiated a phase I study in pts with purine analog-naive relapsed/refractory FL (grades 1 and 2). After leukapheresis, pts receive 4 cycles of fludarabine (25 mg/m²) days 1–3 and cyclophosphamide (250 mg/m²) days 1–3. Four weeks after last chemotherapy, responding patients (CR, CRu, PR) receive escalating doses of ACTC prepared ex vivo from autologous T-cells collected prior to chemotherapy and depleted of regulatory CD4+/CD25+ cells, then expanded and activated using anti-CD3 and anti-CD28. Eight pts have been enrolled to date. Median age is 40.5 y (range: 32–64). Median number of prior therapies is 2 (range: 1–3). Two pts were withdrawn from the study due to hematologic toxicity related to the chemotherapy; one patient has not completed chemotherapy. Of the 5 pts completing chemotherapy, 3 pts achieved a CR and 2 pts achieved a PR; 4 pts received 5 x 10⁹ and 1 patient received 1 x 10¹⁰ CD3+ ACTC. There have been no adverse events related to T-cell infusions. Median follow-up after ACTC infusion is 9 months (range: 2–15 months). Median time to CD4 count >200 /uL was 29 days following T-cell infusion (range 28–127 days). CD4 counts increased in all patients by 1 month after T-cell infusion, with a median increase of 126% from baseline (range 50 to 484%). CD8 counts also increased, with a median increase of 82% (range −4 to 976%). All 5 pts receiving ACTC were anergic to candida antigen by Delayed Type Hypersensitivity (DTH) skin testing before chemotherapy. Three pts developed a positive DTH response to candida antigen 60 days after ACTC infusion. From the start of therapy for patients receiving T-cells, median follow-up is 14 months (range 7–20 months) with median progression-free survival not reached; 4 pts remain in remission and 1 patient had progression of disease. ACTC results in significant CD4+ lymphocyte recovery in previously treated pts receiving cyclophosphamide-fludarabine chemotherapy and compares very favorably with historical controls. T-cell dose escalation is ongoing.