WT1-mRNA dendritic cell vaccination of patients with glioblastoma multiforme, malignant pleural mesothelioma, metastatic breast cancer, and other solid tumors: type 1 T-lymphocyte responses are associated with clinical outcome

Abstract

Cell therapies, including tumor antigen-loaded dendritic cells used as therapeutic cancer vaccines, offer treatment options for patients with malignancies. We evaluated the feasibility, safety, immunogenicity, and clinical activity of adjuvant vaccination with Wilms' tumor protein (WT1) mRNA-electroporated autologous dendritic cells (WT1-mRNA/DC) in a single-arm phase I/II clinical study of patients with advanced solid tumors receiving standard therapy. Disease status and immune reactivity were evaluated after 8 weeks and 6 months. WT1-mRNA/DC vaccination was feasible in all patients, except one. Vaccination was well tolerated without evidence of systemic toxicity. The disease control rate and overall response rate among a total of 39 evaluable patients were 74.4% and 12.8%, respectively. Median overall survival (OS) was 43.7 months among 13 patients with glioblastoma multiforme, 41.9 months among 12 patients with metastatic breast cancer, and 48.8 months among 10 patients with malignant pleural mesothelioma, comparing favourably with historical controls reported in the literature. OS was longer in patients with stable disease at 8 weeks and disease control at 6 months versus patients without disease control at either time point. Disease control and higher OS were associated with antigen-specific type 1 CD4⁺ and/or CD8⁺ T-lymphocyte responses, mainly induced by WT1-mRNA/DC vaccination. Antigen-nonspecific type 2 CD8⁺ T-cell responses were common before WT1-mRNA/DC vaccination but did not show any association with clinical outcome. Collectively, these data indicate that WT1-mRNA/DC vaccination is feasible, safe, and immunogenic and shows clinical activity in patients with advanced solid tumors, suggesting that it has the potential to help improve their survival.

Keywords: Cancer immunotherapy; Clinical trial; Dendritic cell vaccination; Glioblastoma multiforme; Malignant pleural mesothelioma; Metastatic breast cancer; Solid tumors; Type 1 T-lymphocyte response; Wilms’ tumor protein; mRNA.

Fig. 1

Proportions of patients with WT1-specific, KLH-specific, and antigen-nonspecific immune responses (a) and statistical associations among immunological and clinical parameters (b). (a) Responses were determined using intracellular cytokine staining of CD4⁺ and CD8⁺ T-lymphocytes, by WT1-specific HLA-A*02:01 tetramer staining of CD8⁺ T-lymphocytes and by measuring the production of IgG antibodies against WT1. Antigen-nonspecific responses were determined after culture with control medium. Baseline response is defined as values at the PRE time point > 0.1% of cytokine⁺ CD4⁺ or CD8⁺ T-lymphocytes (KLH-responsive or WT1-responsive cases were counted if PRE cytokine⁺ values were at least 50% higher than PRE antigen-nonspecific values); or percentage of WT1 HLA-A*02:01 tetramer⁺ CD8⁺ T-lymphocytes > 0.1% at the PRE time point; or values at PRE > 0.15 for WT1 IgG concentrations in the ELISA. Post-vaccine response was defined as increase of at least 50% in response to WT1 (response to non-KLH-exposed WT1-mRNA/DCs and/or to the WT1 peptide pool) or to KLH or to control medium at the POST and/or FIN time points compared with the PRE time point (as defined in Additional File 1: Methods); or increase of at least 50% in the percentage of WT1 HLA-A*02:01 tetramer⁺ CD8⁺ T-lymphocytes at the POST and/or FIN time points compared with the PRE time point (as defined in Additional File 2: Figure S2); or increase in WT1 IgG concentrations from below (in PRE) to above (in POST and/or FIN) the cutoff absorbance value of 0.15 in the ELISA or increase in WT1 IgG concentrations of at least 50% at the POST and/or FIN time points (as defined in Additional File 1: Methods) from a PRE value of > 0.15 in the ELISA. Numbers in bold indicate where ≥ 50% of patients examined showed a response. (b) Statistical analysis of the data summarized in Table 1 and Fig. 1a was performed to assess associations between clinical response and immune response parameters or between immune response parameters. Each mosaic plot represents a statistically significant 2 × 2 contingency analysis (Additional File 1: Methods) between the parameters indicated. P values are indicated under the mosaic plot ^a = 13 patients with glioblastoma multiforme (GBM), 12 patients with metastatic breast cancer (MBC), 10 patients with malignant pleural mesothelioma (MPM), and 4 patients with other tumors ^b = 12 patients with GBM, 11 patients with MBC, 9 patients with MPM, and 4 patients with other tumors ^c = 13 patients with GBM, 5 patients with HR⁺/HER2⁻ MBC, and 10 patients with MPM * GBM OS from diagnosis > 16.0 months vs. ≤16.0 months & HR⁺/HER2⁻ MBC OS from diagnosis of metastatic disease > 42.1 months vs. ≤42.1 months & MPM OS from diagnosis > 23.4 months vs. ≤23.4 months Abbreviations: WT1 = W1-reactive. KLH = KLH-reactive. CD4⁺ = reactivity in CD4⁺ T-lymphocytes. CD8⁺ = reactivity in CD8⁺ T-lymphocytes. IFN-γ⁺ = interferon-γ production. TNF-α⁺ = tumor necrosis factor-α production. IL-5⁺ = interleukin-5 production. ≥2 epit = number of cases positive for 2 or more WT1 epitopes. # = number of patients. ± = and/or. + = reactivity. − = no reactivity. n = number of patients analyzed. OS = overall survival