CDK12/13 Inhibition Induces Immunogenic Cell Death and Enhances Anti-PD-1 Anticancer Activity in Breast Cancer

Abstract

Background: The T cell response against different tumors is improved by immunogenic cell death (ICD), indicating a role for ICD in augmenting antitumor immunity elicited by the anti-checkpoint antibody anti-programmed death 1 (anti-PD-1). Methods: The effect of SR-4835 on breast cancer was analyzed by cell proliferation and flow cytometry. Calreticulin translocation and HMGB1 and ATP release were detected by flow cytometry, ELISA and luminescence assay, respectively. Immunogenicity in vitro was analyzed by co-culturing of SR-4835 treated cancer cells with bone-marrow derived dendritic cells (BMDCs) and rate of maturation of BMDCs and production of IL-6 in the supernatant were measured. The in vivo antitumor effect was analyzed by syngeneic mouse model followed by flow cytometry for TILs.Results: In the present study, we report a synergistic and durable immune-mediated antitumor response elicited by the combined treatment of SR-4835, a CDK12/13 specific inhibitor, with PD-1 blockade in a murine model of 4T1 breast cancer. The developed combination therapy elicited antitumor activity in immunocompetent mouse tumor models. Furthermore, the SR-4835-treated tumor cells exhibited characteristics of ICD, including the release of high mobility group box 1 (HMGB1) and ATP and the translocation of surface calreticulin (CRT). This activity led to a significant T-cell dependent regression of tumors. The enhanced infiltration of T cells and dendritic cell (DC) activation in the tumors of mice treated with both SR-4835 and anti-PD-1 indicate that this combination treatment promotes an improved immune response and suggests a potential mechanism involving anti-PD-1 and SR-4835 activity that enhances anti-PD-1 effects. Conclusion: The results of the present study demonstrate the potential of CDK12/13 inhibition combined with checkpoint inhibition in breast cancer treatment.

Integration of genetic and epigenetic data pinpoints autoimmune specific remodelling of enhancer landscape in CD4+ T cells

“…54 The top three candidates in our prioritised gene list are IKZF3, CTLA4 and CDK12, which have previously been identified as crucial regulators of T cell activation. 65,68,69 One of the enhancers connected to CTLA4 (chr2:203930706-203942262), was also connected to ICOS and CD28 in the T cell eGRN (Figure 7B). These three genes, all members of the immunoglobulin supergene family, play important distinct as well as synergistic roles in the regulation of T cell responses 66 , and we observed that their expression was significantly upregulated in all subsets of activated T cells (Figure 7C).…”