ID #162 MicroRNA-mediated reprogramming of the tumor microenvironment: enhancing CAR T-cell therapy for Diffuse Intrinsic Pontine Glioma
Kaleem Coleman, Ryan Corbett, Bicna Song, Alex Sickler, Aylar Babaei, Jo Lynne Rokita, Dalia HaydarAbstract
Diffuse Intrinsic Pontine Glioma (DIPG) is a universally fatal pediatric brain tumor with median survival under 12 months. Chimeric antigen receptor (CAR) T-cell therapy shows promise, but its efficacy is limited by a profoundly immunosuppressive tumor microenvironment (TME). Because targeting a single gene or pathway is often insufficient, we explored microRNAs (miRs)—small non-coding RNAs that regulate gene expression—as a strategy to broadly reprogram the TME and enhance CAR T-cell function.
We performed small RNA and bulk RNA sequencing on post-mortem DIPG tumors, matched normal brain tissue, and healthy controls. Analysis revealed dysregulated immune-regulatory miRs (miR-21, miR-450b, miR-3065) and downregulation of genes critical for immune activation (EFNB2, MEF2C, PPP3CA). Integrated miRNA–mRNA correlation analysis identified strong predicted interactions (miR-21→MEF2C, miR-450b→EFNB2, miR-3065→PPP3CA), enabling construction of an immune-regulatory network underlying DIPG-associated immune suppression.
To assess therapy-induced miR dynamics, glioma-bearing mice were treated with B7-H3 CAR T cells, control CARs, or left untreated. Principal Component Analysis demonstrated distinct clustering of B7-H3 CAR-treated tumors, and differential expression analysis identified therapy-associated miRs (miR-344, let-7d, miR-155, miR-30c) linked to macrophage polarization and T-cell dysfunction. Preliminary in vitro studies further show that incorporating select miRs during CAR T-cell manufacturing enhances CAR T-cell persistence in repeat stimulation assays and improves cytotoxicity.
Collectively, these data highlight miRs as critical modulators of DIPG immune suppression and reveal their dynamic regulation by CAR T-cell therapy. By leveraging miR-mediated reprogramming of the TME, this approach offers a novel strategy to improve CAR T-cell efficacy and therapeutic outcomes for children with DIPG.