Safety, mucosal and systemic immunopotency of an aerosolized adenovirus-vectored vaccine against SARS-CoV-2 in rhesus macaques.

Mucosal immunity provides a potential for preventing initial infection and stopping subsequent transmission of SARS-CoV-2. Here, we examined the safety and immunogenicity of a replication-defective adenovirus type-5 vectored vaccine (Ad5-nCov) encoding SARS-CoV-2 spike protein delivered by nebulization inhalation in rhesus macaques. The vaccine-associated clinical pathology and toxicity were not observed in the NHP model. The extensive safety study indicated that Ad5-nCoV was mainly confined to the organs related to respiratory system and was rapidly cleared away from the system. Our results showed that Ad5-nCoV delivered by inhalation robustly elicited both systematic and mucosal immune responses against SARS-nCoV-2 and variants. Thus, Ad5-nCoV inhalation may provide an effective, safe and non-invasive vaccination strategy for the control of SARS-CoV-2.

A tritherapy combination of a fusion protein vaccine with immune-modulating doses of sequential chemotherapies in an optimized regimen completely eradicates large tumors in mice.

Tumor-induced immunosuppression plays a critical role in both impeding tumor-specific immune responses and limiting the effects of cancer immunotherapy. Analyses of regulatory cells recruited during the growth of the E7-expressing tumor, TC-1, revealed a high percentage of regulatory T cells (Tregs) as well as myeloid-derived suppressor cells (MDSCs) in spleens and tumors. In this study, we proposed that treatment with immune-modulating doses of cyclophosphamide (CTX) and all-trans retinoic acid (ATRA) would result in a beneficial tumor microenvironment with the suppression of Tregs and MDSCs and, thus, enhance the effect of a human papillomavirus protein vaccine. Our results showed that CTX preconditioning and persistent ATRA treatment along with the vaccine achieved long-term survival and induced long-term memory responses. However, the effect of the antitumor response sharply declined when the tritherapy was initiated after the optimal therapeutic time. The more intensive regimen could rescue the effect of the tritherapy accompanied by the decreased percentage of Tregs and MDSCs in spleens and tumors. Besides, a favorable host environment was created by the reduced secretion of interleukin-10 and 6 and vascular endothelial growth factor (VEGF) in the tumor niche and decreased the expression of phosphorylation-signal transducer and activator of transcription 3 of TC-1 tumors. Our data shed light on the immune-modulating doses of sequential chemoimmunotherapeutic strategy targeting not only the tumor but also its microenvironment, which suggests a potential clinical benefit for the immunotherapy of HPV-associated malignancies.

Combination of all-trans retinoic acid and a human papillomavirus therapeutic vaccine suppresses the number and function of immature myeloid cells and enhances antitumor immunity.

Despite advances in the development of human papillomavirus (HPV) prophylactic vaccines, little progress has been made in the field of therapeutic vaccines in recent years. In the present study, we found a significant accumulation of immature myeloid cells (ImC) in large TC-1 tumors and demonstrated that a HPV therapeutic vaccine restored antitumor immune responses with the correction of aberrant myeloid cell differentiation by all-trans retinoic acid (ATRA). Our study demonstrated that combining ATRA with vaccination not only decreased the number of Gr-1+ CD11b+ ImC, but for the first time also suppressed the function of Gr-1+ CD11b+ ImC with decreased expression of CD80. Furthermore, large numbers of CD11c+ CD80+, CD11c+ CD86+, and CD11c+ MHCII+ mature dendritic cells were recruited. The combination therapy generated significantly increased numbers of functional E7-specific T cells with elevated interferon- secretion and enhanced cytotoxic T-cell activity. These findings suggest potential clinical benefits for the combined use of ATRA and HPV therapeutic vaccines.

A novel therapeutic fusion protein vaccine by two different families of heat shock proteins linked with HPV16 E7 generates potent antitumor immunity and antiangiogenesis.

Human papillomaviruses (HPV), particularly HPV16, is considered a necessary cause of cervical and oral cancer. Thus, the development of a therapeutic vaccine against HPV is important for the control of cervical cancer. However, therapeutic vaccination has been limited by inadequate antigen-specific immune responses. Heat shock proteins (HSP), including calreticulin (CRT), HSP70 and gp96, have been shown to act as potent immunoadjuvant to enhance antigen-specific tumor immunity. Previous studies have shown that N domain CRT (NCRT) or C-terminal half of HSP70 (hsp) linked with HPV16 E7 are capable of inducing potent antigen-specific CTL activity in experimental animal models. Here we developed a recombinant NCRT/E7/hsp fusion protein to investigate the synergistic effects of NCRT and hsp for enhancing the potency of HPV16 E7 therapeutic vaccine and evaluated the immune responses induced by this fusion protein. Our results demonstrated that NCRT and hsp synergistically exhibited significant increases in E7-specific CD8(+) T cell responses and impressive antitumor effects against E7-expressing tumors. Furthermore, the NCRT/E7/hsp fusion protein also generates potent antiangiogenic effects. These results indicate that NCRT/E7/hsp fusion protein is a promising therapeutic vaccine for treatment of cervical cancer through a combination of antigen-specific immunotherapy and antiangiogenesis, with possible therapeutic potential in clinical settings.