Repeated dose (14days) rat intramuscular toxicology study of Her1 vaccine

► We assessed the toxicity of two strengths/formulations of Her1 vaccine in rats. ► Her1 vaccine was administered intramuscularly for 14days. ► Her1 immunization induced an inflammatory effect at the injection site. ► Her1 was well tolerated, with findings largely attributable to the adjuvant used. Our goal was to assess the toxicity of two strengths (200 and 400μg) of HER1 cancer vaccine (Center of Molecular Immunology, Cuba), presented in two different formulations, in Sprague Dawley rats after repeated intramuscular administration (14days). Four groups (5 animals/sex) were established: Control, Placebo (adjuvant), and two Treated groups receiving a dose representing ten times of human total dose (10×), 28.6 and 57.1μg/kg. Clinical observations, body weight and rectal temperature were measured during the study. Clinical pathology analysis was performed, besides gross necropsy and histological examination of tissues on animals at the end of the assay. The assay ended with a 100% survival. Injection site damage, with the presence of cysts and granulomas, was observed in adjuvant and vaccine treated groups, with most severe cases predominating at higher strength. Administration of Placebo and Her1 vaccine induced increase in polymorphonuclear cells, with relative lymphopenia conditioned by primary neutrophilia. In summary, results suggest that Her1 immunization was capable of inducing an inflammatory effect at the injection site, leading to systemic alterations, more significant at higher strength (400μg, 57.1μg/kg), probably affected by the immunizations’ schedule used. The vaccine was shown to be well tolerated without any obvious signs of systemic toxicity, with findings largely attributable to the adjuvant used.