Anti-PD-1 monoclonal antibodies, nivolumab and pembrolizumab, and anti-CTLA-4 antibody ipilimumab are being in clinic trials to treat melanoma. Here, we performed a meta-analysis to evaluate the efficacy and toxicity of them against advanced melanoma. Eleven reports from 6 randomized control trials on treating metastatic melanoma, which were divided into 3 subgroups, nivolumab/pembrolizumab versus chemotherapy, nivolumab versus ipilimumab, and nivolumab-plus-ipilimumab versus ipilimumab, were included and the meta-analysis was performed for each subgroup. The outcome measures were objective response rates (ORR), median progression free survival (PFS), 1-year overall survival rates (OS), and toxicity estimated by grade 3 to 4 adverse events. For nivolumab/pembrolizumab versus chemotherapy, nivolumab versus ipilimumab, and nivolumab-plus-ipilimumab versus ipilimumab, the pooled risk ratios (RR) of the ORR were 3.43 (95% CI: 2.57–4.58), 2.51 (95% CI: 2.03–3.09), and 3.28 (95% CI: 2.58–4.17), respectively. The pooled HR of PFS were 0.42 (95% CI: 0.36–0.49), 0.58 (95% CI: 0.50–0.66), and 0.41 (95% CI: 0.30–0.52), respectively. The pooled RR of 1-year OS was 1.37 (95% CI: 1.08–1.74) and 1.54 (95% CI: 0.90–2.63) for nivolumab versus ipilimumab and nivolumab-plus-ipilimumab versus ipilimumab. These results suggested that anti-PD-1 monotherapy and nivolumab-plus-ipilimumab therapy had ORR and PFS benefit compared with the control group. Anti-PD-1 treatment increased 1-year OS for patients compared with ipililumab treatment. But there is no significantly difference on 1-year OS between the nivolumab-plus-ipilimumab treatment and the ipilimumab treatment group. The toxicity analysis showed that there is less risk of adverse events in the anti-PD-1 treatment group compared with the chemotherapy and ipilimumab group. Combining nivolumab with ipilimumab increased the risk for high-grade adverse events compared with ipilimumab alone but the adverse events were generally manageable. Anti-PD-1 monotherapy and nivolumab-plus-ipilimumab therapy improved ORR and prolonged PFS of patients with advanced melanoma and the adverse events are generally manageable. The therapy is indeed a promising approach for treatment of advanced melanoma.

To search for more effective tuberculosis (TB) subunit vaccines, antigens expressed in different growth stages of Mycobacterium tuberculosis (M. tuberculosis), such as RpfE (Rv2450c) produced in the stage of resuscitation, Mtb10.4 (Rv0288), Mtb8.4 (Rv1174c), ESAT6 (Rv3875), Ag85B (Rv1886c) mainly secreted by replicating bacilli, and HspX (Rv2031c) highly expressed in dormant bacilli, were selected to construct six fusion proteins: ESAT6-Ag85B-MPT64_190-198-Mtb8.4 (EAMM), Mtb10.4-HspX (MH), ESAT6-Mtb8.4, Mtb10.4-Ag85B, ESAT6-Ag85B, and ESAT6-RpfE. The six fusion proteins were separately emulsified in an adjuvant composed of N,N’-dimethyl-N, N’-dioctadecylammonium bromide (DDA), polyribocytidylic acid (poly I:C) and gelatin to construct subunit vaccines, and their protective effects against M. tuberculosis infection were evaluated in C57BL/6 mice. Furthermore, the boosting effects of EAMM and MH in the adjuvant of DDA plus trehalose 6,6'-dimycolate (TDM) on BCG-induced immunity were also evaluated. It was found that the six proteins were stably produced in E. coli and successfully purified by chromatography. Among them, EAMM presented the most effective protection against M. tuberculosis. Interestingly, the mice that received EAMM+MH had significantly lower bacterial counts in the lungs and spleens than the single protein vaccinated groups, and had the same effect as those that received BCG. In addition, EAMM and MH could improve BCG-primed protective efficacy against M. tuberculosis infection in mice. In conclusion, the combination of EAMM and MH containing antigens from both replicating and dormant stages of the bacilli could induce robust immunity against M. tuberculosis infection in mice and may serve as promising subunit vaccine candidate.

Tuberculosis (TB) is a chronic disease mainly caused by Mycobacterium tuberculosis. The function of T cells usually decreased and even exhausted in severe TB such as multiple drug resistant TB (MDR-TB), which might lead to the failure of treatment in return. The mechanism of T cell dysfunction in TB is still not clear. In this study we set up a mouse model of T cell dysfunction by persistent M. tuberculosis antigen stimulation and investigated the therapeutic role of interleukin 2 (IL-2) in it. C57BL/6 mice were primed with Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and boosted repeatedly with a combination of M. tuberculosis fusion proteins Mtb10.4-HspX (MH) plus ESAT6-Ag85B-MPT64 _<190−198>-Mtb8.4-Rv2626c (LT70) or MH plus ESAT6 and CFP10 with adjuvant of N, N′-dimethyl-N, N′-dioctadecylammonium bromide (DDA) plus polyinosinic-polycytidylic acid (Poly I:C). Following persistent antigen stimulation, the mice were treated with IL-2 and the therapeutic effects were analyzed. The results showed that compared with the mice that received transient antigen stimulation (boost twice), persistent antigen stimulation (boost more than 10 times) resulted in decrease of antigen specific IFN-γ and IL-2 production, reduction of memory CD8⁺ T cells, over-expression of immune checkpoint programmed cell death protein 1 (PD-1), and impaired the protective immunity against bacterial challenge. Treating the T cell functionally exhausted mice with IL-2 restored antigen-specific T cell responses and protective efficacy. In conclusion, persistent stimulation with M. tuberculosis antigens induced T cell dysfunction, which could be restored by complement of IL-2.

To develop an effective subunit vaccine which could target tubercle bacilli with different metabolic states and provide effective protective immunity, we fused antigens ESAT6, Ag85B, peptide 190–198 of MPT64, and Mtb8.4 mainly expressed by proliferating bacteria and latency-associated antigen Rv2626c together to construct a multistage protein ESAT6-Ag85B-MPT64_(190–198)-Mtb8.4-Rv2626c (LT70 for short) with the molecular weight of 70 kDa. The human T-cell responses to LT70 and other antigens were analyzed. The immune responses of LT70 in the adjuvant of DDA and Poly I:C and its protective efficacy against Mycobacterium tuberculosis (M. tuberculosis) infection in C57BL/6 mice were evaluated. The results showed that LT70 was stably produced in Escherichia coli and could be purified by successive salting-out and chromatography. LT70 could be strongly recognized by human T cells from TB patients and persons who are supposed latently infected with M. tuberculosis. The subunit vaccine LT70 generated strong antigen-specific humoral and cell-mediated immunity, and induced higher protective efficacy (5.41±0.37 Log₁₀ CFU in lung) than traditional vaccine Bacillus Calmette-Guerin (6.01±0.33 Log₁₀ CFU) and PBS control (6.53±0.26 Log₁₀ CFU) at 30 weeks post vaccination (10 weeks post-challenge) against M. tuberculosis infection (p < 0.05). These findings suggested that LT70 would be a promising subunit vaccine candidate against M. tuberculosis infection.