Immune self-tuning in renal cell carcinoma patients

e22069

Background: Renal cell carcinoma (RCC) cells can inhibit protective antitumor immunity by secretion of immunosuppressive factors leading to the induction of regulatory T cells. The objective of this study was to investigate the prognostic impact of mRNA expression levels of IL10, TGFβ and forkhead box transcription factor (FoxP3) mRNA in peripheral blood mononuclear cells (PBMCs) of metastatic RCC patients before receiving treatment with sorafenib. Methods: PBMCs of 46 patients were assessed for their expression levels of TGFβ, IL10 and FoxP3 by quantitative RT-PCR. Clinical features considered included ECOG performance status, hemoglobin, alkaline phosphatase, and calcium concentrations. Disease evaluation was performed every 8 weeks following RECIST criteria. Relationship between pre-treatment factors and survival were examined in univariate analyses and subsequently by multivariate analysis using a stepwise Cox regression model. Results: In contrast to FoxP3, mRNA expression levels of IL10 and TGFβ were significantly higher in the 46 RCC patients compared to healthy volunteers: Median expression levels [ratio marker /housekeeping gene PBGD] were 5.56E-05 vs 2.05E-04 (P=0.034) for IL10 and 7.38E-02 vs 3.04E- 01 (P=0.023) for TGFβ. Univariate analysis revealed a negative prognostic influence of IL10 on progression free survival (p=0.04) and on overall survival, although not significant (P= 0.063). Surprisingly, high TGFβ and FoxP3 expression levels had a positive influence on progression free (P<0.001 and P=0.047, respectively) and overall survival (P<0.001 and P= 0.031, respectively). In the multivariate analysis low ECOG performance status and high TGFβ mRNA expression levels were independently associated with worse progression free (P=0.001 and P=0.054,) and worse overall survival (P=0. 006 and P< 0.001, respectively). Conclusions: RCC caused an immune-suppressive phenotype in PBMC characterized by increased mRNA expression levels of IL10 and TGFβ. Surprisingly, in contrast to IL10, a high TGFβ mRNA expression level was an independent good prognostic factor. Whether this observation can be attributed to recently described immune promoting functions of TGFβ needs to be determined.

No significant financial relationships to disclose.

Clinical and immune responses of WT1-peptide vaccination in patients with acute myeloid leukemia

2511

Background: The transcription factor Wilms tumor protein (WT) 1 belongs to a new generation of tumor antigens, as it is essential for tumor cell proliferation. WT1 is highly expressed both in myeloid leukemias and many carcinomas. This phase 2 proof-of-concept trial was initiated to determine immunogenicity and toxicity of vaccination with a novel HLA-A2-restricted WT1 peptide vaccine. Methods: Sixteen HLA-A2-positive patients with acute myeloid leukemia and one patient with myelodysplasia received 3–18 vaccinations (median 8) of WT1. 126–134 peptide (0.2 mg) together with the T helper protein keyhole limpet hemocyanin (1 mg) and in addition GM-CSF (75 mcg for four days) and. Twelve patients had elevated blast counts at study entry and 5 patients complete remission with high risk for relapse. Results: Six of 12 patients with presence of leukemic blasts had evidence of antileukemic activity. One patient achieved complete remission for 12 months. The patient with myelodysplasia RAEB II had a major response of neutrophils and platelets. Two patients had minor responses with transient clearance of peripheral blasts or improvement of hematopoiesis, and two patients achieved disease stabilization for 3 and 14 months. WT1 transcripts as molecular disease marker decreased in 5 of these 6 patients and also in 4 of 5 high-risk patients. No significant toxicity occurred. The generation of a WT1-specific T cell response in peripheral blood and bone marrow was detected in 9 of 13 patients by tetramer analysis and 8 of 13 patients by intracellular cytokine staining. Conclusion: These results show that WT1 vaccination can induce functional T cell responses associated with antileukemic activity and warrant trials of WT1 vaccination in patients at high risk of relapse and with WT1-expressing carcinomas.

No significant financial relationships to disclose.

Adjuavnt tyrosinase peptide vaccination in patients with resected stage III/IV melanoma

2570

Background: This phase II study was undertaken to evaluate the immunogenicity and clinical efficacy of vaccination with tyrosinase peptides as adjuvant treatment in melanoma patients after multiple relapses. Methods: Stage III/IV melanoma patients after complete resection of relapses were vaccinated with tyrosinase peptides together with GM-CSF and KLH. Vaccination was given bi-weekly times 4, followed by monthly times 8 in absence of relevant disease progression. Tyrosinase-specific T cells were quantitated and characterized ex vivo by intracellular cytokine flow cytometry. Results: 44 patients were accrued with a median of 5.8 (range 2–25) previous relapses at cutaneous /s.c. only (n = 11), ln (n = 30) and/or visceral sites (n = 7). 11 patients received less than 6 vaccinations due to rapid progression. Of 32 patients evaluable for immunological response 16 (50%) displayed pre-vaccine spontaneous tyrosinase-specific T cells (median 0.32%). In 7 of the 15 patients without pre-existing T cells tyrosinase-specific T cells were induced after 6 vaccinations (median 0.08% CD3+CD8+ T cells) and in 10 of 12 patients after 12 vaccinations (median 0.36%, p = 0.03 compared to 6 vaccinations). Similarly, in 9 of the 16 patients with pre-existing T cell responses the frequency of tyrosinase-specific T cells did increase after 6 cycles (median 0.43 %), but in none of 10 patients with pre-existing T cells an increase was observed after 12 vaccinations (median 0.20%). Both, the spontaneous and the vaccine-induced T cells were predominantly of effector and effector-memory phenotype. With respect to clinical efficacy vaccination was terminated after 3 to 9 cycles due to disease progression in 19 of 44 patients. Of the remaining 25 patients receiving all 12 vaccinations 7 (16% of all 44 enrolled) had a favourable clinical course with cessation of recurrences. Conclusions: Taken together, this study shows high immunogenicity of the vaccine in patients with limited tumor burden associated with clinical efficacy. In case of a spontaneous pre-existing T cell response to the vaccine peptides, however, this could not, or only transiently be augmented.

No significant financial relationships to disclose.