Phase I/II study of GM-CSF gene-transduced allogeneic prostate cancer cellular immunotherapy (GVAX IT) in advanced prostate cancer patients made lymphopenic by chemotherapy and infused with autologous peripheral blood mononuclear cells (MC)

Abstract

14635 Background: GVAX IT has been tested in phase I/ II and is currently being tested in phase III clinical trials of patients (pts) with androgen-independent prostate carcinoma (AIPC). Immunological and PSA responses have been described in men receiving GVAX IT. Preclinical studies have shown that antitumor immune responses induced by GVAX IT could be augmented further by making animals lymphopenic and reconstituting with lymphocytes prior to vaccination. A clinical trial was designed to study the effects of lymphopenic reconstitution in pts with AIPC. Methods: All pts had MC collection by leukapheresis pre-treatment. Study groups were as follows: Arm A - GVAX IT given every two weeks for 6 months; Arm B - Cyclophosphamide (350 mg/m2 IV on days 1–3), MC infusion on day 6, GVAX IT on day 7, then every 2 weeks for 6 months; Arm C - Cyclophosphamide (350 mg/m2 IV on days 1–3) and fludarabine (20 mg/m2 IV on days 1–3), MC infusion on day 6, GVAX IT on day 7, then every 2 weeks for 6 months. Results: Seven pts have been treated thus far and completed at least 2 GVAX IT treatments. Pts had ECOG performance status ≤ 1, castrate testosterone levels, ≤ 1 prior chemotherapy regimen and measurable or evaluable metastatic AIPC. Lymphopenia was induced in all pts enrolled in Arms B and C, with recovery of total granulocytes and lymphocytes within 4 weeks following treatment. Monitoring of humoral and cellular immunological responses is underway and shall be presented. Conclusions: GVAX IT and lymphopenic reconstitution is feasible in men with AIPC. Analysis of clinical and immune response is ongoing. Supported by DAMD grant PC020094 and generous support of Mr. Tom Denhart, the Chiles Foundation and the Murdock Trust. [Table: see text]