Elraglusib (9-ING-41), a selective small-molecule inhibitor of glycogen synthase kinase-3 beta, reduces expression of immune checkpoint molecules PD-1, TIGIT and LAG-3 and enhances CD8+ T cell cytolytic killing of melanoma cells

Abstract

Background Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase with multiple roles in tumour growth, cell invasion and metastasis. We have previously established GSK-3 as an upstream regulator of PD-1 gene expression in CD8 + T cells and demonstrated that GSK-3 inhibition is as effective as anti-PD-1 mAb blockade in controlling tumour growth. Elraglusib (9-ING-41) is a specific small-molecule inhibitor of GSK-3β with clinical activity in patients with advanced cancers, including a patient with refractory melanoma whose response provided the rationale for the current study. Methods The B16 melanoma mouse model was used to observe the effect of elraglusib on tumour growth either as a single agent or in combination (simultaneously and sequentially) with anti-PD-1 mAb treatment. B16 tumour cells were implanted in either the flank, brain or both locations, and Kaplan–Meier plots were used to depict survival and significance determined using log rank tests. Expression of the immune checkpoint molecules, TIGIT, LAG-3 and PD-1, was evaluated using flow cytometry alongside expression of the chemokine receptor, CXCR3. Further evaluation of PD-1 expression was determined through RT-qPCR and immunohistochemistry. Results We demonstrated that elraglusib has a suppressive effect against melanoma as a single agent and enhanced anti-PD-1 therapy. There was a synergistic effect when elraglusib was used in combination with anti-PD-1 mAb, and an even greater effect when used as sequential therapy. Suppression of tumour growth was associated with a reduced expression of immune checkpoint molecules, PD-1, TIGIT and LAG-3 with upregulation of CXCR3 expression. Conclusions These data highlight the potential of elraglusib as an immune-modulatory agent and demonstrate the benefit of a sequential approach with immune checkpoint inhibition followed by GSK-3β inhibition in melanoma and provide a rationale for clinical investigation of elraglusib combined with immune checkpoint inhibitory molecules, including those targeting PD-1, TIGIT and LAG-3. This has several potential implications for current immunotherapy regimes, including possibly reducing the intensity of anti-PD-1 mAb treatment needed for response in patients receiving elraglusib, especially given the benign adverse event profile of elraglusib observed to date. Based on these data, a clinical study of elraglusib, an anti-PD-1 mAb and chemotherapy is ongoing (NCT NCT05239182).

GSK-3 inhibitor elraglusib enhances tumor-infiltrating immune cell activation in tumor biopsies and synergizes with anti-PD-L1 in a murine model of colorectal cancer

“…We also noted that immune cell segments showed differential protein expression based on the proximity to the tumor where tumor-infiltrating immune cells had decreased expression of immune checkpoints (PD-L1, Tim-3, PD-1) and Treg markers (CD25, CD127) as compared to tumor-adjacent immune cells regardless of timepoint. While the downregulation of immune checkpoint proteins PD-1, TIGIT, and LAG-3 by elraglusib has been previously described in melanoma models (47), our findings regarding VISTA and PD-L2 have not yet been reported. These novel observations regarding emerging immune checkpoint inhibitors should be included in future correlative studies regarding GSK-3 inhibition.…”

Programmed cell death‐1 blockade therapy in melanoma: Resistance mechanisms and combination strategies

“…Previous articles reported that GSK‐3β inhibition not only disturbed the motion and invasive activity of melanoma cells, but also inhibited the transcription of LAG‐3 and PDCD1 for CD8 + T cells 62,63 . Based on this, the GSK‐3β inhibitor elraglusib enhances the efficacy of anti‐PD‐1 immunotherapy by relieving the exhausted condition of tumor‐specific CD8 + T cells via down‐regulation of PD‐1, LAG‐3, and TIGIT expression 64 . Sustained angiogenesis is one of the most famous hallmarks of cancer.…”

“…62,63 Based on this, the GSK-3β inhibitor elraglusib enhances the efficacy of anti-PD-1 immunotherapy by relieving the exhausted condition of tumor-specific CD8 + T cells via down-regulation of PD-1, LAG-3, and TIGIT expression. 64 Sustained angiogenesis is one of the most famous hallmarks of cancer. Using inhibitors to disrupt the vascular endothelial growth factor (VEGF) signal is a classic cancer treatment strategy.…”

Targeted engagement of β-catenin-Ikaros complexes in refractory B-cell malignancies

“…These findings suggest that GSK3β-inhibition, when used in combination with existing regimen for refractory B-ALL and other lymphoid malignancies, could substantially deepen treatment responses and overcome mechanisms of conventional drug resistance. GSK3β small molecule inhibitors, including LY2090314, AZD1080, Laduviglusib (CHIR99021), Tideglusib and Elraglusib , have demonstrated safety and tolerability at micromolar plasma concentrations (Cmax) [47][48][49][50][51][52][53] . Among the reported adverse effects of LY2090314 in clinical trials (Cmax micromolar) was lymphopenia (Figure S11d), which is consistent with the unique dependency of B-lymphoid cells on GSK3β-mediated degradation of β-catenin discovered in this study.…”