Immunotherapy of patients with pancreatic adenocarcinoma: Influence of adjuvants

Abstract

15542 Background: Because peptide vaccines are poorly immunogenic, combination with immunological adjuvants such as GM-CSF, have been given in previous phase I/II studies of the hTERT peptide vaccine GV1001. The objective of the present study was to compare the immunological response after GV1001 treatment, combined with different immunological adjuvants. Methods: The study was an open phase II study of patients with irresectable adenocarcinoma of the pancreas, 18–75 years old. All patients received GV1001 as an intradermal injection eight times over a period of 10 weeks using imiquimod as an adjuvant in treatment group 1 and imiquimod and GM- CSF as adjuvants in treatment group 2 and 3. In addition, patients in group 2 received palliative irradiation (3Gy × 10) prior to immunotherapy while patients in group 3 received one dose of cyclophosphamide three days prior to start of immunotherapy. Primary endpoint was immune response, measured by DTH skin test reaction and specific T-cell response. Results: All together 15, 10 and 14 patients were included in groups 1–3 respectively. For the evaluable patients the immune response in treatment group 1, 2 and 3 was 39%, 50% and 64%, respectively. A total of 221 adverse events (AEs) were reported by 39 patients, 86 in treatment group 1, 41 in treatment group 2 and 94 in treatment group 3. The incidence rate (number of AEs per patient per month) of adverse events was lower in treatment group 2 (0.67 AEs/patient/months) compared to treatment groups 1 and 3 with incidence rates of 1.13 and 1.27, respectively.Most AEs were scored as unlikely related to study treatment and were of mild to moderate severity. Conclusions: The study demonstrated that immune response to GV1001 can be obtained using different treatment regimens, but none of these adjuvant regimens generated higher response levels than GM-CSF alone. It can further be concluded that GV1001 is well tolerated, both in combination with palliative irradiation and with cyclophosphamide. No significant financial relationships to disclose.