Gustav Gaudernack

BACKGROUND: The growth and recurrence of several cancers appear to be driven by a population of cancer stem cells (CSCs). Glioblastoma, the most common primary brain tumor, is invariably fatal, with a median survival of approximately 1 year. Although experimental data have suggested the importance of CSCs, few data exist regarding the potential relevance and importance of these cells in a clinical setting. METHODS: We here present the first seven patients treated with a dendritic cell (DC)-based vaccine targeting CSCs in a solid tumor. Brain tumor biopsies were dissociated into single-cell suspensions, and autologous CSCs were expanded in vitro as tumorspheres. From these, CSC-mRNA was amplified and transfected into monocyte-derived autologous DCs. The DCs were aliquoted to 9-18 vaccines containing 10(7) cells each. These vaccines were injected intradermally at specified intervals after the patients had received a standard 6-week course of post-operative radio-chemotherapy. The study was registered with the ClinicalTrials.gov identifier NCT00846456. RESULTS: Autologous CSC cultures were established from ten out of eleven tumors. High-quality RNA was isolated, and mRNA was amplified in all cases. Seven patients were able to be weaned from corticosteroids to receive DC immunotherapy. An immune response induced by vaccination was identified in all seven patients. No patients developed adverse autoimmune events or other side effects. Compared to matched controls, progression-free survival was 2.9 times longer in vaccinated patients (median 694 vs. 236 days, p = 0.0018, log-rank test). CONCLUSION: These findings suggest that vaccination against glioblastoma stem cells is safe, well-tolerated, and may prolong progression-free survival.

Patients with inoperable pancreatic cancer have a dismal prognosis with a mean life expectancy of 3-6 months. New treatment modalities are thus urgently needed. Telomerase is expressed in 85-90% of pancreas cancer, and immunogenic telomerase peptides have been characterised. A phase I/II study was conducted to investigate the safety, tolerability, and immunogenecity of telomerase peptide vaccination. Survival of the patients was also recorded. Forty-eight patients with non-resectable pancreatic cancer received intradermal injections of the telomerase peptide GV1001 at three dose levels, in combination with granulocyte-macrophage colony-stimulating factor. The treatment period was 10 weeks. Monthly booster vaccinations were offered as follow-up treatment. Immune responses were measured as delayed-type hypersensitivity skin reaction and in vitro T-cell proliferation. GV1001 was well tolerated. Immune responses were observed in 24 of 38 evaluable patients, with the highest ratio (75%) in the intermediate dose group. Twenty-seven evaluable patients completed the study. Median survival for the intermediate dose-group was 8.6 months, significantly longer for the low- (P = 0.006) and high-dose groups (P = 0.05). One-year survival for the evaluable patients in the intermediate dose group was 25%. The results demonstrate that GV1001 is immunogenic and safe to use. The survival data indicate that induction of an immune response is correlated with prolonged survival, and the vaccine may offer a new treatment option for pancreatic cancer patients, encouraging further clinical studies.

This paper describes a new cell isolation and HLA typing technique, which permits cell separation and HLA class I or class II typing to be performed in 70 min. Magnetic monodisperse microspheres (Dynabeads TM) were coated with monoclonal antibodies (MAbs) specific for the CD8 T cell antigen or for HLA class II monomorphic epitopes. They could then be used to obtain HLA class I or class II positive cells directly from ACD blood in approximately 15 min by the use of magnetic separation. The cells (attached to the microspheres) were subsequently used in microcytotoxic HLA typing (total incubation time of 55 min) using acridin orange/ethidiumbromide to stain viable (yellow) and dead (red) cells. It was found that this immunomagnetic (IM) HLA typing technique was specific, has a sensitivity superior to that observed for conventional microcytotoxicity assays and gave low background staining. IM HLA-ABC typing of 50 healthy donors and 10 patients and IM HLA-DR typing of 25 healthy donors and 30 patients gave results corresponding well with that obtained independently by conventional HLA typing (concordancy rates 92-100%). Furthermore, the IM HLA typing technique permitted reliable HLA class II typing of blood cells from six patients where conventional HLA class II typing was impossible. The IM HLA typing technique also enables HLA class I and II typing to be quickly and reliably performed on cells from ACD blood of cadaveric donors.

K-RAS mutations are frequently found in adenocarcinomas of the pancreas, and induction of immunity against mutant ras can therefore be of possible clinical benefit in patients with pancreatic cancer. We present data from a clinical phase I/II trial involving patients with adenocarcinoma of the pancreas vaccinated by i.d. injection of synthetic mutant ras peptides in combination with granulocyte-macrophage colony-stimulating factor. Forty-eight patients (10 surgically resected and 38 with advanced disease) were treated on an outpatient basis. Peptide-specific immunity was induced in 25 of 43 (58%) evaluable patients, indicating that the protocol used is very potent and capable of eliciting immune responses even in patients with end-stage disease. Patients followed-up for longer periods showed evidence of induction of long-lived immunological memory against the ras mutations. CD4(+) T cells reactive with an Arg12 mutation also present in the tumor could be isolated from a tumor biopsy, demonstrating that activated, ras-specific T cells were able to selectively accumulate in the tumor. Vaccination was well tolerated in all patients. Patients with advanced cancer demonstrating an immune response to the peptide vaccine showed prolonged survival from the start of treatment compared to non-responders (median survival 148 days vs. 61 days, respectively; p = 0.0002). Although a limited number of patients were included in our study, the association between prolonged survival and an immune response against the vaccine suggests that a clinical benefit of ras peptide vaccination may be obtained for this group of patients.