Anticancer effectiveness of vaccination based on xenogeneic embryo proteins applied in different schedules

Abstract

The aim: To evaluate anticancer activity of vaccination with chicken embryo proteins (CEP) applied in different schedules. Materials and Methods: C57Bl mice were vaccinated with CEP before (prophylactic schedule) or after (different therapeutic schedules with or without preliminary tumor removal) the Lewis lung carcinoma cells transplantation. The latent period of tumor development, tumor volume and metastasis rate were evaluated. Results: Potent antimetastatic effect of CEP-based vaccination was seen in case of therapeutic regimen after primary tumor removal. The metastasis inhibition index (MII) reached 96.9 and 97.8% on 18th and 34th day after tumor removal, respectively. When CEP vaccination was performed in the settings of therapeutic regimen without primary tumor removal the anticancer effect was evident only if vaccinations started as early as 24 h after the cancer cells injections. The highest MII achieved in such condition was 77.6%, tumor volume in the group of vaccinated animals was by 53.1–42.1% lower than in the control tumor-bearing mice. CEP vaccination before tumor challenge (prophylactic immunization) led to a statistically significant prolongation of the latent period of tumor development, a reduction of tumor volume (35.8–48.8% compared to control unvaccinated mice) and a marked inhibition of metastasis (MII was 71.1%). Conclusion: Vaccination based on CEP exhibited both prophylactic and therapeutic anticancer effects. The last one is more pronounced when the vaccination starts shortly after the primary tumor resection. Key Words: chicken embryo proteins, anticancer activity, Lewis lung carcinoma.