RESUMO
Direct vaccination with mRNA encoding tumor antigens is a novel and promising approach in cancer immunotherapy. CureVac's mRNA vaccines contain free and protamine-complexed mRNA. Such two-component mRNA vaccines support both antigen expression and immune stimulation. These self-adjuvanting RNA vaccines, administered intradermally without any additional adjuvant, induce a comprehensive balanced immune response, comprising antigen specific CD4+ T cells, CD8+ T cells and B cells. The balanced immune response results in a strong anti-tumor effect and complete protection against antigen positive tumor cells. This tumor inhibition elicited by mRNA vaccines is a result of the concerted action of different players. After just two intradermal vaccinations, we observe multiple changes at the tumor site, including the up-regulation of many genes connected to T and natural killer cell activation, as well as genes responsible for improved infiltration of immune cells into the tumor via chemotaxis. The two-component mRNA vaccines induce a very fast and boostable immune response. Therefore, the vaccination schedules can be adjusted to suit the clinical situation. Moreover, by combining the mRNA vaccines with therapies in clinical use (chemotherapy or anti-CTLA-4 antibody therapy), an even more effective anti-tumor response can be elicited. The first clinical data obtained from two separate Phase I/IIa trials conducted in PCA (prostate cancer) and NSCLC (non-small cell lung carcinoma) patients have shown that the two-component mRNA vaccines are safe, well tolerated and highly immunogenic in humans.
Assuntos
Antígenos de Neoplasias/imunologia , Vacinas Anticâncer/genética , Vacinas Anticâncer/imunologia , Carcinoma Pulmonar de Células não Pequenas/terapia , Neoplasias da Próstata/terapia , Animais , Antígenos de Neoplasias/genética , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/imunologia , Linhagem Celular , Terapia Combinada , Células HeLa , Humanos , Imunoterapia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias da Próstata/genética , Neoplasias da Próstata/imunologia , RNA Mensageiro/genética , Vacinas de DNARESUMO
Direct vaccination with messenger RNA (mRNA) molecules encoding tumor-associated antigens is a novel and promising approach in cancer immunotherapy. The main advantage of using mRNA for vaccination is that the same molecule not only provides an antigen source for adaptive immunity, but can simultaneously bind to pattern recognition receptors, thus stimulating innate immunity. However, achieving both features remains challenging, as the complexation of mRNA required for immune-stimulating activity may inhibit its translatability. In this study, we present a new and more effective vaccine design: a two-component mRNA-based tumor vaccine that supports both: antigen expression and immune stimulation, mediated by Toll like receptor 7 (TLR7). The two-component mRNA vaccines, containing free and protamine-complexed mRNA, induce balanced adaptive immune responses providing humoral as well as T cell mediated immunity. This balanced immune response is based on the induction of antigen-specific CD4(+) T helper cells and cytotoxic CD8(+) T cells. Once activated, these CD4(+) and CD8(+) T cells secrete a wide set of cytokines, which drive a TH1 response. Immunization with the two-component vaccines induces sustained memory responses, mediated by antigen-specific memory T cells. Moreover, treatment of mice with the two-component mRNA vaccine mediates a strong antitumor response against OVA-expressing tumor cells, not only in a prophylactic but also in a therapeutic setting. In conclusion, two-component mRNA vaccines with self-adjuvanting activity induce balanced adaptive immune responses and mediate sustained antitumor activity.