B-cell acute lymphoblastic leukemia promotes an immune suppressive microenvironment that can be overcome by IL-12

Abstract

Immunotherapies have revolutionized the treatment of B-cell acute lymphoblastic leukemia (B-ALL), but the duration of responses is still sub-optimal. We sought to identify mechanisms of immune suppression in B-ALL and strategies to overcome them. Plasma collected from children with B-ALL with measurable residual disease after induction chemotherapy showed differential cytokine expression, particularly IL-7, while single-cell RNA-sequencing revealed the expression of genes associated with immune exhaustion in immune cell subsets. We also found that the supernatant of leukemia cells suppressed T-cell function ex vivo. Modeling B-ALL in mice, we observed an altered tumor immune microenvironment, including compromised activation of T-cells and dendritic cells (DC). However, recombinant IL-12 (rIL-12) treatment of mice with B-ALL restored the levels of several pro-inflammatory cytokines and chemokines in the bone marrow and increased the number of splenic and bone marrow resident T-cells and DCs. RNA-sequencing of T-cells isolated from vehicle and rIL-12 treated mice with B-ALL revealed that the leukemia-induced increase in genes associated with exhaustion, including Lag3, Tigit, and Il10, was abrogated with rIL-12 treatment. In addition, the cytolytic capacity of T-cells co-cultured with B-ALL cells was enhanced when IL-12 and blinatumomab treatments were combined. Overall, these results demonstrate that the leukemia immune suppressive microenvironment can be restored with rIL-12 treatment which has direct therapeutic implications.

Multicolor Light-Induced Immune Activation via Polymer Photocaged Cytokines

“…In prior work, , we demonstrated that rIL-12 could potentiate the therapeutic effects of the T cell engager blinatumomab (Blincyto) ex vivo, and here we further demonstrate the NIR photocontrol of this enhanced activity via NIR illumination of cCy-PEG-conjugated rIL-12. This finding is significant as conventional rIL-12 therapies are well known to be associated with severe hematologic and hepatic toxicities that may potentially compound with those observed from blinatumomab when delivered in combination.…”

“…In prior work, we demonstrated that recombinant IL-12 can enhance the cytolytic activity of the T cell bispecific immunotherapy, blinatumomab, currently approved to treat patients with relapsed and refractory B cell acute lymphoblastic leukemia (B-ALL). , To determine whether IL-12-cCy-PEG can likewise improve blinatumomab-induced cytolysis in an NIR light-dependent manner, we treated co-cultures of labeled primary human CD8+ T cells and CD19+ NALM-6 B-ALL cells with blinatumomab and rIL-12 or IL-12-cCy-PEG, with and without NIR light exposure, and measured CD19-specific cell lysis and T cell activation via flow cytometry and IFNγ ELISA, respectively (Figure a–c). As anticipated, we observed no significant change in blinatumomab-induced cytolysis or T cell activation following co-culture with IL-12-cCy-PEG without illumination; however, following NIR LED exposure of the protein, we observed an increase in both CD19-specific lysis and IFNγ secretion that was statistically indistinguishable from that enhanced by rIL-12.…”

Multicolor Light-Induced Immune Activation via Polymer Photocaged Cytokines

“…In prior work, 30, 35 we demonstrated that rIL-12 could potentiate the therapeutic effects of the T cell engager, blinatumomab (Blincyto ® ) ex vivo and here we further demonstrate the NIR photo-control of this enhanced activity via NIR illumination of cCy-PEG conjugated rIL-12. This finding is significant as conventional rIL-12 therapies are well-known to be associated with severe hematologic and hepatic toxicities that may potentially compound with those observed from blinatumomab when delivered in combination.…”

“…34 Such approaches when utilized with the NIR photocaging strategy describe here may find strong utility in intravital imaging applications [24][25][26] as well as ex vivo studies of organoids and embryo-like body development where high spatial control of protein delivery is necessary for proper cell organization. 27,28 In prior work, 30,35 we demonstrated that rIL-12 could potentiate the therapeutic effects of the T cell engager, blinatumomab (Blincyto ® ) ex vivo and here we further demonstrate the NIR photo-control of this enhanced activity via NIR illumination of cCy-PEG conjugated rIL-12. This finding is significant as conventional rIL-12 therapies are wellknown to be associated with severe hematologic and hepatic toxicities that may potentially compound with those observed from blinatumomab when delivered in combination.…”

“…In prior work, we demonstrated that recombinant IL-12 can enhance the cytolytic activity of the T cell bispecific immunotherapy, blinatumomab, currently approved to treat patients with relapsed and refractory B cell acute lymphoblastic leukemia (B-ALL). 29, 30 To determine whether IL-12-cCy-PEG can likewise improve blinatumomab-induced cytolysis in an NIR light-dependent manner, we treated cocultures of labeled primary human CD8+ T cells and CD19+ NALM-6 B-ALL cells with blinatumomab and rIL-12 or IL-12-cCy-PEG, with and without NIR light exposure and measured CD19-specific cell lysis and T cell activation via flow cytometry and IFNγ ELISA, respectively (Figure 3a-c) . As anticipated, we observed no significant change in blinatumomab-induced cytolysis or T cell activation following co-culture with IL-12-cCy-PEG without illumination; however, following NIR LED exposure of the protein, we observed an increase in both CD19-specific lysis and IFNγ secretion that was statistically indistinguishable from that enhanced by rIL-12.…”