Anti-CD20 therapy induces a memory Th1 response through the IFN-γ/IL-12 axis and prevents protumor regulatory T-cell expansion in mice

Abstract

The long-lasting clinical response by lymphoma patients to anti-CD20 therapy has been attributed to the induction of an anti-tumor adaptive immunity. We previously demonstrated that a CD4-dependent mechanism is responsible for the long-term protection of CD20(+) tumor-bearing mice by anti-CD20 treatment. Here, we compare tumor immunity in tumor-bearing animals that did or did not receive anti-CD20 treatment. Splenic CD4(+)FoxP3(+) regulatory T cells (Tregs) expanded substantially in untreated mice that exhibited then a reduced survival, whereas Tregs depletion led to long-term survival of the animals, suggesting the establishment of a Treg-dependent immunosuppressive environment after tumor injection. Strikingly, anti-CD20 therapy reversed the initial expansion of Tregs, and was accompanied by a marked increase in the number of Th1 cells, with no detectable change in Th2 and Th17 cell numbers. Interleukin-12 serum level was also increased by the anti-CD20 treatment, and activated myeloid dendritic cells producing interleukin-12 could be detected in lymph nodes of treated animals, while interferon-γ blockade strongly reduced survival. Also, CD4(+) effector memory T cells were evidenced in surviving animals, and the transfer of CD4(+) T cells induced long-term protection. Thus, anti-CD20 therapy promotes strong anti-tumor adaptive immunity, opposes Treg expansion and inhibits tumor cells from maintaining an immunosuppressive environment.

A TLR7 agonist enhances the antitumor efficacy of obinutuzumab in murine lymphoma models via NK cells and CD4 T cells

“…30 In murine models some studies report a primary role for phagocytic mechanisms. 26, 31, 32, 33 However, others have demonstrated the importance of ADCC by NK cells and these studies used a similar EL4hCD20 model to ours, 19, 20 suggesting that the mechanism of action may vary depending on the tumor model, location and antibody isotype. Here we have demonstrated that for obinutuzumab, when given in combination with a systemic TLR7 agonist, long-term tumor-free survival appears to be dependent on NK cells and CD4 + T cells with macrophages and monocytes only able to mediate short-term increases in survival.…”

“…A type I anti-CD20 mAb was previously shown to eradicate EL4hCD20 cells in C57Bl/6 mice by the same mechanism. 19, 20 Taken together with data that R848 and other TLR agonists can increase levels of activating FcγR but decrease levels of the inhibitory FcγRIIb, 21, 22 this suggests that R848 is potentiating obinutuzumab effector mechanisms, in particular ADCC by NK cells, rather than priming other immunological pathways. Indeed, in vivo priming of NK cells with R848 was necessary for enhanced IFNγ production by NK cells upon engagement of Fc receptors by obinutuzumab.…”

“…34 TLR agonists can potentially have a diverse role in activating the immune system and thus may enhance antibody-mediated tumor cell killing by numerous different mechanisms. Given that both anti-CD20 mAb 20 and R848 therapy 35, 36 can prime Th1 immune responses through NK cell-mediated IFNγ release and production of IL-12 by dendritic cell, and that TLR7 agonism 37, 38 leads to direct induction of CD4 T-cell proliferation and stimulation of CD4 T cells through activation of antigen-presenting cell, it is likely that obinutuzumab and R848 act in synergy to activate tumor-specific CD4 + T cells. It was previously shown in wild-type mice bearing EL4hCD20 that protection from tumor rechallenge post anti-CD20 mAb therapy was restricted to hCD20 + tumors, suggesting a vaccination effect.…”

Interferon-γ Drives Treg Fragility to Promote Anti-tumor Immunity

“…This was a direct effect of IFNγ or Nrp1 −/− T reg -derived IFNγ as no other cells types were included in the in vitro experiments. Previous studies have suggested that IL12 can impact T reg suppression and induce IFNγ expression (Dominguez-Villar et al, 2011; Koch et al, 2012; Zhao et al, 2012), while others show that IFNγ can limit T reg expansion (Deligne et al, 2015; Olalekan et al, 2015; St Rose et al, 2013; Visperas et al, 2014). However, the direct effect of IFNγ on T reg function in vivo had surprisingly not been appreciated.…”

The cryo-thermal therapy eradicated melanoma in mice by eliciting CD4+ T-cell-mediated antitumor memory immune response

“…In the late stage of the treatment, CD4 + T cells in the treated mice were differentiated into predominant Th1, CD4 + CTL and Tfh subsets, which could maintain long-term antitumor immunity. By far, hyperthermia, therapeutic vaccines (dendritic cell vaccine) and antitumor mAb treatment are shown to mainly drive differentiation of CD4 + T cells into Th1 cells, 39, 40, 41, 42 whereas multiple CD4 + T-cell lineages induced by the therapeutic strategies participated in antitumor immunity has not been reported. This study revealed that multiple CD4 + T-cell lineages differentiation was significantly dominated at the different stage after the treatment, which would be a characteristic hallmark of long-term CD4 + T-cell immunity triggered by the treatment.…”