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BACKGROUND Minocycline blocks microglial TNF signaling and downstream NF-κB activation, which reduces the mesenchymal phenotype in preclinical models of GBM. Primary analysis of the D-TERMINED trial identified a maximal tolerated dose (MTD) of oral minocycline at 150 mg BID in combination with temozolomide and radiation. In the overall population, the secondary objective of improved PFS was not met. Here, response is further stratified by biomarkers delineating mesenchymal subtype (OLIG2, CD44), microglial activation (IBA-1), and NF-κB signaling (P-p65). METHODS Patients with newly diagnosed high-grade glioma received continuous oral minocycline during concurrent chemoradiation and adjuvant temozolomide. Twenty patients were included in the MTD efficacy population. Within this cohort, immunohistochemistry for OLIG2, CD44, IBA-1, and P-p65 was performed on nineteen patient tumor samples. For each biomarker, the mean percent positivity or number/HPF was compared between patients who exceeded or did not exceed expected PFS. Spearman correlation coefficients were also generated for pairwise comparison of these biomarkers. RESULTS In patients with high PFS, 12.7% of tumor cells were positive for OLIG-2, 36.5% for CD44, and 23.9% for P-p65, with 41.7 cells/HPF positive for IBA-1. Comparatively, in patients with low PFS, 9.4% of tumor cells were positive for OLIG-2 (p = 0.59), 34.1% for CD44 (p = 0.77), and 22.3% for P-p65 (p = 0.85), with 31.1 cells/HPF positive for IBA-1 per HPF (p = 0.38). The only biomarkers demonstrating significant relationship were P-p65 and IBA-1, with a rank correlation of 0.637 (p = 0.007). CONCLUSIONS Exploratory analysis of D-TERMINED concludes that OLIG-2, CD44, IBA-1, and P-p65 are not predictive of improved PFS within high-grade glioma patients treated with SOC and minocycline. Concurrent use of minocycline with chemoradiation is therefore not indicated in these or unselected populations. Significant correlation is seen between IBA-1 and P-p65, biomarkers of microglial activation and NF-κB signaling. SPONSORSHIP: Funding provided by the Musella Foundation and NIH grant P30CA042014.

Medulloblastoma (MB) is the most common malignant primary pediatric brain tumor. The Group 3 molecular subgroup of Medulloblastoma (Group 3 MB) is the deadliest with only 30% long term survival. Irradiation for Group 3 Medulloblastoma is required for long term survival of children. Methods to enhance the effect of irradiation against Group 3 MB are an active area of investigation. Immunotherapy using the anti-CD47 treatment has shown promise in treating Group 3 MB. We recently demonstrated that irradiation significantly enhanced anti-CD47-mediated phagocytosis of high-grade glioma cells in vitro. Furthermore, mice engrafted with human high-grade glioma that received anti-CD47 combined with irradiation showed a significant increase in the survival rate and a significant decrease in tumor growth than those that received a single treatment. We have now extended these studies to demonstrate the enhancement of anti-CD47-dependent phagocytosis of human Group 3 MB with irradiation. We also analyzed normal human neural stem cells exposed to the same treatments to assess for the potential toxicity that uniquely exists with this treatment combination.

Large, multisubunit Ccr4-Not complexes are evolutionarily conserved global regulators of gene expression. Deletion of CCR4 or several components of Ccr4-Not complexes results in abnormally large cells. Since yeast must attain a critical cell size at Start to commit to division, the large size of ccr4Δ cells implies that they may have a size-specific proliferation defect. Overexpression of CLN1, CLN2, CLN3, and SWI4 reduces the size of ccr4Δ cells, suggesting that ccr4Δ cells have a G1-phase cyclin deficiency. In support of this, we find that CLN1 and CLN2 expression and budding are delayed in ccr4Δ cells. Moreover, overexpression of CCR4 advances the timing of CLN1 expression, promotes premature budding, and reduces cell size. Genetic analyses suggest that Ccr4 functions independently of Cln3 and downstream of Bck2. Thus, like cln3Δbck2Δ double deletions, cln3Δccr4Δ cells are also inviable. However, deletion of Whi5, a transcriptional repressor of CLN1 and CLN2, restores viability. We find that Ccr4 negatively regulates the half-life of WHI5 mRNAs, and we conclude that, by modulating the stability of WHI5 mRNAs, Ccr4 influences the size-dependent timing of G1-phase cyclin transcription.