Preclinical safety assessment of a therapeutic human papillomavirus DNA vaccine combined with intravaginal interleukin-7 fused with hybrid Fc in female rats.

This study was conducted to establish the toxicological profile of combination treatment with therapeutic HPV DNA vaccines (GX-188E) and the long-acting form of recombinant human interleukin-7 fused with hybrid Fc (IL-7hyFc). GX-188E was administered intramuscularly by electroporation with or without IL-7hyFc intravaginally once per 2 weeks for 8 weeks (five times) in female Sprague-Dawley rats. Because up-regulation of immune responses and migration of antigen-specific T cells in cervicoviginal tissue were predicted as therapeutic effects, we distinguished adverse effects from therapeutic effects based on the severity of the systemic immune response, reversibility of lymphoid tissue changes, target tissue damage, and off-target immune responses. We observed that the number of neutrophils was increased, and the number of lymphocytes was decreased in the blood. Further, myofiber degeneration, necrosis, fibroplasia, and cell infiltration were observed at the GX-188E administration site. These changes were fully or partially recovered over a 4-week period. Analysis of lymphocytes in spleen revealed that CD4+ T cells and total T cells decreased in rats treated with GX-188E in combination with a high dose of IL-7hyFc (1.25 mg/animal). However, these changes were not considered adverse because they were transient and may have been related to electroporation-mediated DNA delivery or the local migration of lymphocytes induced by IL-7. Therefore, the potential toxicity of the combination of GX-188E and IL-7hyFc treatment was comparable to that of GX-188E treatment alone, and the no observed adverse effect level for GX-188E with IL-7hyFc was considered as 320 µg/animal for GX-188E and 1.25 mg/animal for IL-7hyFc.

Non-clinical safety assessment of single and repeated intramuscular administration of a human papillomavirus-16/18 vaccine in rabbits and rats.

The human papillomavirus (HPV)-16/18 vaccine (Cervarix®) is a prophylactic vaccine for the prevention of cervical cancer. The vaccine contains recombinant virus-like particles assembled from the L1 major capsid proteins of the cervical cancer-causing viral types HPV-16 and HPV-18, and Adjuvant System 04 (AS04), which contains the immunostimulant MPL and aluminium salt. To evaluate potential local and systemic toxic effects of the HPV-16/18 vaccine or AS04 alone, three repeated-dose studies were performed in rabbits and rats. One rabbit study also included a single-dose evaluation. In rabbits (~2.5 kg), the full human dose (HD) of the vaccine was evaluated (0.5 ml per injection site), and in rats (~250 g), 1/5 HD of vaccine was evaluated, corresponding to ≥ 12 times the dosage in humans relative to body weight. In both animal models, the treatment-related changes included a slight transient increase in the number of circulating neutrophils as well as a local inflammatory reaction at the injection site. These treatment-related changes were less pronounced after four doses of AS04 alone than after four doses of the HPV-16/18 vaccine. Additional treatment-related changes in the rat included lower albumin/globulin ratios and microscopic signs of inflammation in the popliteal lymph nodes. In both animal models, 13 weeks after the fourth dose, recovery was nearly complete, although at the injection site in some animals there were signs of discoloration, muscle-fibre regeneration and focal points of macrophage infiltration. Therefore, in these non-clinical models, the single and repeated dose administrations of the HPV-16/18 vaccine or AS04 alone were safe and well tolerated.

Initial preclinical safety of non-replicating human endogenous retrovirus envelope protein-coated baculovirus vector-based vaccines against human papillomavirus.

Human endogenous retrovirus (HERV) envelope protein-coated, baculovirus vector-based HPV 16 L1 (AcHERV-HPV16L1) is a non-replicating recombinant baculoviral vaccine. Here, we report an initial evaluation of the preclinical safety of AcHERV-HPV16L1 vaccine. In an acute toxicity study, a single administration of AcHERV-HPV16L1 DNA vaccine given intramuscularly (i.m.) to mice at a dose of 1 × 10(8) plaque-forming units (PFU) did not cause significant changes in body weight compared with vehicle-treated controls. It did cause a brief increase in the weights of some organs on day 15 post-treatment, but by day 30, all organ weights were not significantly different from those in the vehicle-treated control group. No hematological changes were observed on day 30 post-treatment. In a range-finding toxicity study with three doses of 1 × 10(7) , 2 × 10(7) and 5 × 10(7) PFU once daily for 5 days, the group treated with 5 × 10(7) PFU showed a transient decrease in the body weights from day 5 to day 15 post-treatment, but recovery to the levels similar to those in the vehicle-treated control group by post-treatment day 20. Organ weights were slightly higher for lymph nodes, spleen, thymus and liver after repeated dosing with 5 × 10(7) PFU on day 15, but had normalized by day 30. Moreover, repeated administration of AcHERV-HPV16L1 did not induce myosin-specific autoantibody in serum, and did not cause immune complex deposition or tissue damage at injection sites. Taken together, these results provide preliminary evidence of the preclinical safety of AcHERV-based HPV16L1 DNA vaccines in mice.

Lack of effects on fertility and developmental toxicity of a quadrivalent HPV vaccine in Sprague-Dawley rats.

Human papillomavirus (HPV) infection is one of the most common sexually transmitted diseases, with approximately half of the HPV-infected people being adolescents and young adults. A recently developed quadrivalent HPV vaccine, GARDASIL((R)), has been shown to be highly effective in the prevention of a number of HPV-mediated diseases. The objective of the present study was to evaluate the potential effects of the vaccine on female fertility and F1 development, growth, behavior, and reproductive performance. In addition, anti-HPV antibodies in the F0 females and F1 offspring were measured during the study. Two groups of 65 virgin Sprague-Dawley rats were administered two or four intramuscular injections of the vaccine (full human dose of 0.5 mL at 5 and 2 weeks prior to mating, on Gestation Day [GD] 6, and Lactation Day [LD] 7; or GD 6 and LD 7 only). Additional groups of rats were administered phosphate-buffered saline or Merck Aluminum Adjuvant (MAA) at the same four times. All females were mated to males of the same stock. Cesarean sections were performed on 22/group on GD 21, 22/group were allowed to deliver, and remaining females used for blood collections or replacements. F0 female fertility parameters were evaluated. An extensive number of prenatal, perinatal, and postnatal parameters were evaluated in the F1 generation. There were no unscheduled deaths during the study. There was no evidence of toxicity in the F0 females given either MAA or vaccine. There were no effects on the fertility or reproductive performance of the F0 females. There was no evidence of developmental toxicity to the F1 generation, including fetal body weight and morphology, postnatal growth and development, behavior, and reproductive performance. The quadrivalent vaccine induced a specific antibody response to the four HPV types in the F0 female rats following one or multiple injections. Antibodies against all four HPV types were transferred to the F1 generation during gestation and/or lactation, likely via the placenta and milk, respectively. The passively transferred antibodies persisted up to Postnatal Day 77 when they were last measured. These results demonstrate that this quadrivalent HPV vaccine had no detectable adverse effects in either the treated F0 female rats or the F1 generation.

Evaluation of a 9-valent HPV vaccine in Sprague-Dawley rats: Nonclinical studies assessing general, reproductive, and developmental toxicity.

GARDASIL®9, a 9-valent vaccine against human papillomavirus (9vHPV), was developed to prevent diseases mediated by HPV types 6/11/16/18/31/33/45/52/58. During the development of the vaccine, three nonclinical safety studies were conducted to evaluate repeat-dose toxicity and prenatal and postnatal developmental toxicity in Sprague-Dawley rats. In all studies, the vaccine was administered via intramuscular injections of 0.5 mL (the human dose) divided equally into each quadriceps muscle. In the repeat-dose toxicity study, potential local and systemic toxic effects of the 9vHPV vaccine were evaluated after 4 doses given 21 days apart and after a 21-day recovery period. In the prenatal study, virgin females were dosed at 5 and 2 weeks prior to mating and on Gestation Day [GD] 6 (3 total doses). Potential postnatal developmental toxicity of the vaccine formulation was evaluated after 4 total doses (premating to lactation). There were no treatment-related unscheduled deaths in any studies. In the 3-month repeat-dose toxicity study, no adverse effects in male or female rats were observed. Anticipated systemic effects representing immunological responses and local inflammatory reactions at the injection sites were noted in the vaccine-treated groups, with a trend toward recovery by the end of the 21-day recovery period. In the prenatal developmental toxicity study, there was no evidence of toxicity in females given the vaccine. There were no effects on fertility or reproductive performance of the parental females and no evidence of developmental toxicity. In the postnatal study, there was no evidence of toxicity in vaccine-treated females and no evidence of developmental toxicity based on standard postnatal parameters, including behavioral testing and reproductive performance. The vaccine induced antibody responses in all studies and vaccine-specific antibodies were detected in offspring in the developmental toxicity studies. These results support the favorable safety profile of GARDASIL®9.

Evaluation of the intramuscular administration of Cervarix™ vaccine on fertility, pre- and post-natal development in rats.

Cervarix™ is a prophylactic human papillomavirus (HPV)-16/18 vaccine for the prevention of cervical cancer. It contains GSK Biologicals' proprietary Adjuvant System AS04. The objective of this study was to investigate the effects of Cervarix™ and of AS04 on female fertility and pre- and post-natal development in Sprague Dawley rats. Female rats were injected with vaccine, AS04, or saline 30 days before mating and on Gestation Days 6, 8, 11 and 15. Each dose of vaccine was one-fifth the human dose volume. Treatment of rats with vaccine or AS04 was not associated with any systemic toxicity and had no impact on female fertility. There were no adverse effects on pre- or post-natal development of litters from treated rats, as judged by fetal evaluation at Gestation Day 20, and growth and survival of pups to postnatal Day 25. These results support the use of the vaccine in the targeted human population.