Enhanced anti-tumor immunity generated by Rituximab-coated tumor cell vaccine

HER2 expression in renal cell carcinoma is rare and negatively correlated with that in normal renal tissue

The aim of this study was to evaluate the status of HER2 protein expression in patients with renal cell carcinoma (RCC) and to determine its prognostic significance. A total of 42 paraffin-embedded tumor tissues and 42 additional corresponding adjacent normal tissues from RCC patients were randomly collected and studied using immunohistochemistry (IHC). Protein samples of 6 fresh specimens from tumor and adjacent normal tissues obtained during surgery were extracted and tested using western blotting to confirm the IHC results. Of the 42 tumor tissues and adjacent normal tissues tested, IHC showed that 7 tumors (16.67%) and 33 adjacent normal tissues (78.57%) expressed the HER2 protein. In addition, results of the western blotting revealed weak HER2 reactivity in primary tumor cells in two of 6 specimens obtained during surgery. All 6 normal tissues showed positive expression, which was in accordance with the outcome of IHC. In conclusion, HER2 is frequently expressed in normal renal tissues and rarely expressed in RCC tissues. Furthermore, the HER2 status of normal tissue is negatively correlated with that of the RCC tissues (r=-0.410, P=0.007) and the TNM stage (r=-0.246, P=0.027), suggesting that HER2 is involved in RCC oncogenesis.

Improved tumor immunity using anti-tyrosinase related protein-1 monoclonal antibody combined with DNA vaccines in murine melanoma

Passive immunization with monoclonal antibody TA99 targeting melanoma differentiation antigen tyrosinase-related protein-1 (Tyrp1; gp75) and active immunization with plasmid DNA encoding altered Tyrp1 both mediate tumor immunity in the B16 murine melanoma model. We report here that TA99 enhances Tyrp1 DNA vaccination in the treatment of B16 lung metastases, an effect mediated by immunologic mechanisms as Tyrp1 has no known role in regulating tumor growth. TA99 is shown to increase induction of anti-Tyrp1 CD8+T-cell responses to DNA vaccination against Tyrp1 as assessed by IFN-gamma ELISPOT assays. Immunohistochemistry studies reveal that TA99 localizes rapidly and specifically to B16 lung nodules. Augmentation of T-cell responses is dependent on the presence of tumor as well as on activating Fc receptors. Furthermore, TA99 enhances DNA vaccination against a distinct melanoma antigen, gp100(pmel17/silver locus), improving antitumor efficacy, augmenting systemic CD8+ T-cell responses to gp100, and increasing CD8+ T-cell infiltration at the tumor site. Epitope spreading was observed, with CD8+ T-cell responses generated to Tyrp1 peptide in mice receiving gp100 DNA vaccination in the presence of TA99. Finally, we show that TA99 improves therapeutic efficacy of DNA vaccination combined with adoptive T-cell transfer in treatment of established subcutaneous B16 melanoma. In conclusion, TA99 enhances DNA vaccination against both the target antigen Tyrp1 and a distinct melanoma antigen gp100 in an Fc receptor-dependent mechanism, consistent with enhanced cross-presentation of tumor-derived antigen. Monoclonal antibodies should be tested as vaccine adjuvants in the treatment of cancer.