Journal of Clinical Oncology, 2007 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 25, No 18S (June 20 Supplement), 2007: 4543
© 2007 American Society of Clinical Oncology

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Abstract

RAS peptide vaccination in resected pancreatic cancer patients - persistence of anti tumour response and long term survival

Ullevaal University Hospital, Oslo, Norway; Norwegian Radiumhospital, Oslo, Norway; National Hospital, Oslo, Norway; Gemvax, Prosgrunn, Norway

4543

Background: K-RAS mutations are found in most adenocarcinoma of the pancreas, and targeting mutant RAS by vaccination may be of clinical importance. The present follow-up study was performed to determine whether or not mutant RAS specific T cells were still present in long term survivors seven to nine years after postoperative adjuvant vaccination with synthetic mutant RAS peptides Methods: During 1995–98, all together 23 patients were recruited into two clinical studies. The patients in CTN95002 (n = 10) were given a single mutant RAS peptide (100µg) corresponding to the RAS mutation identified in the patient’s tumor. Patients in CTN98010 (n = 13) were given a mixture of seven mutant RAS peptides, (700µg), corresponding to the most common mutations in pancreatic adenocarcinoma, in a 10 week vaccination regimen, using GM-CSF as an adjuvant, and boosters for an extended period. Immune responses were measured as skin reaction (DTH) and/or in vitro T-cell response. Blood samples from the five patients, still alive in 2006, were investigated by in vitro T-cell proliferation assay for immunological memory. Results: The five surviving patients were all immune responders during the primary vaccination period. Analysis of T-cell reactivity was performed seven (one patient), eight (one patient) and nine years (three patients) after resection/vaccination. Three patients still showed immune responses against the vaccine given previously. T cell reactivity against the Gly12Val mutation was observed in one patient receiving this peptide. In another patient a strong T cell reactivity against all seven peptides present in the vaccine, was observed. Conclusions: Long term survival beyond seven to nine years was only found in patients who primarily responded immunologically on the RAS-vaccination. Long term immunological memory can be induced by peptide vaccination.

No significant financial relationships to disclose.

Abstract presentation from the 2007 ASCO Annual Meeting