Discovery of Hydroxyamidine Based Inhibitors of IDO1 for Cancer Immunotherapy with Reduced Potential for Glucuronidation.

Following the impressive success of checkpoint inhibitors in the treatment of cancer, combinations of IDO1 inhibitors with PD-1/PD-L1 antibodies are in clinical development aiming to increase response rates. Using the hydroxyamidine pharmacophore of the IDO1 inhibitor INCB14943 as a starting point for the design of new inhibitors, the potential shortcomings of extensive hydroxyamidine glucuronidation in humans was addressed. Compounds were optimized using a stability assay with recombinant UGT1A9 enzyme together with the measurement of glucuronide formation in human hepatocytes. Optimized analog 24 showed cellular and biochemical IDO1 IC50 values in the low nanomolar range, a suitable in vitro ADME/PK profile, and efficacy in an animal model of cancer. In a humanized liver mouse model the lead compound exhibited significantly reduced glucuronidation compared to epacadostat (2).

Genetic rearrangements result in altered gene expression and novel fusion transcripts in Sézary syndrome.

Sézary syndrome (SS) is an aggressive, leukemic cutaneous T-cell lymphoma variant. Molecular pathogenesis of SS is still unclear despite many studies on genetic alterations, gene expression and epigenetic regulations. Through whole genome and transcriptome next generation sequencing nine Sézary syndrome patients were analyzed in terms of copy number variations and rearrangements affecting gene expression. Recurrent copy number variations were detected within 8q (MYC, TOX), 17p (TP53, NCOR1), 10q (PTEN, FAS), 2p (DNMT3A), 11q (USP28), 9p (CAAP1), but no recurrent rearrangements were identified. However, expression of five genes involved in rearrangements (TMEM244, EHD1, MTMR2, RNF123 and TOX) was altered in all patients. Fifteen rearrangements detected in Sézary syndrome patients and SeAx resulted in an expression of new fusion transcripts, nine of them were in frame (EHD1-CAPN12, TMEM66-BAIAP2, MBD4-PTPRC, PTPRC-CPN2, MYB-MBNL1, TFG-GPR128, MAP4K3-FIGLA, DCP1A-CCL27, MBNL1-KIAA2018) and five resulted in ectopic expression of fragments of genes not expressed in normal T-cells (BAIAP2, CPN2, GPR128, CAPN12, FIGLA). Our results not only underscored the genomic complexity of the Sézary cancer cell genome but also showed an unpreceded large variety of novel gene rearrangements resulting in fusions transcripts and ectopically expressed genes.

In Vivo Silencing of A20 via TLR9-Mediated Targeted SiRNA Delivery Potentiates Antitumor Immune Response.

A20 is an ubiquitin-editing enzyme that ensures the transient nature of inflammatory signaling pathways induced by cytokines like TNF-α and IL-1 or pathogens via Toll-like receptor (TLR) pathways. It has been identified as a negative regulator of dendritic cell (DC) maturation and attenuator of their immunostimulatory properties. Ex vivo A20-depleted dendritic cells showed enhanced expression of pro-inflammatory cytokines and costimulatory molecules, which resulted in hyperactivation of tumor-infiltrating T lymphocytes and inhibition of regulatory T cells. In the present study, we demonstrate that a synthetic molecule consisting of a CpG oligonucleotide TLR9 agonist linked to A20-specific siRNAs silences its expression in TLR9+ mouse dendritic cells in vitro and in vivo. In the B16 mouse melanoma tumor model, silencing of A20 enhances the CpG-triggered induction of NFκB activity followed by elevated expression of IL-6, TNF-α and IL-12. This leads to potentiated antitumor immune responses manifested by increased numbers of tumor-specific cytotoxic T cells, high levels of tumor cell apoptosis and delayed tumor growth. Our findings confirm the central role of A20 in controlling the immunostimulatory potency of DCs and provide a strategy for simultaneous A20 silencing and TLR activation in vivo.

Identification of multiple complex rearrangements associated with deletions in the 6q23-27 region in Sézary syndrome.

The 6q23-27 region, recurrently deleted in Sézary syndrome (SS), was characterized at the molecular level in 13 SS patients and SS cell line SeAx. Using fine-tiling comparative genomic hybridization, deletions within the 6q23-27 region were detected in half of the samples (six patients and SeAx). All samples with deletions were further analyzed by ligation-mediated PCR. In addition, in one patient sample and in SeAx, paired-end next-generation sequencing was performed on the HiSeq2000 Illumina platform. Using those techniques, 23 rearrangements associated with the deletions were identified. The majority of rearrangements showed enormous complexity and diversity, including eight inversions, three transpositions, and four translocations (with chromosomes 3, 17, 10, and 12). Fifteen genes were disrupted by those rearrangements, the MYB proto-oncogene three times and the interleukin-22 receptor subunit alpha-2 gene (IL22RA2) twice. All three patients with MYB alterations showed low MYB expression, whereas seven of the remaining patients showed overexpression. Most patients overexpressing MYB also presented increased expression of MYC, HSPA8, and BCL2. Five gene fusions were identified, of which two, CCDC28A-IL22RA2 and AIG1-GOSR1, both in SeAx, were in the same orientation and were expressed at the messenger RNA level.

Immunomodulatory effects of sorafenib on peripheral immune effector cells in metastatic renal cell carcinoma.

BACKGROUND: Tyrosine kinase inhibitors (TKI) such as sorafenib have substantially improved the prognosis of metastatic renal cell carcinoma (mRCC) patients, but long-term remissions have only been reached with immunotherapy. Sequencing or combining TKI treatment with immunotherapy may represent an attractive therapeutic concept. However, in vitro data have shown that TKI may not only affect tumour cells, but also inhibit signalling in immune effector cells. Therefore, we asked whether sorafenib had an influence on peripheral immune effector cells in a cohort of 35 mRCC patients receiving sorafenib treatment. METHODS: Peripheral blood (pB) samples were analysed at baseline and after 8 weeks of treatment. IL-10 and TGF-ß mRNA levels were quantified by RT-PCR; regulatory T cell (Treg) counts and intracellular cytokine responses (TNF-α, IFN-γ, IL-10 and TGF-ß) of mononuclear cell subsets were determined by flow cytometry after in vitro stimulation with PMA/ionomycin. RESULTS: Sorafenib did not alter the elevated TGF-ß and IL-10 mRNA levels or elevated frequencies of IL-10 and TGF-ß producing monocytes and had no influence on type 1 cytokine responses in pB. CD4+CD25(high) FOXP3+/CD3+ T cells, likely representing Treg cells, decreased during sorafenib therapy. CONCLUSIONS: In vivo, sorafenib treatment was associated with a decrease in frequency of Treg cells without influencing the function of peripheral immune effector cells. Therefore, although sorafenib did not convert the immunosuppressive phenotype associated with mRCC, it seemed to be a possible candidate for combination with immunotherapy.

Systemic immune tuning in renal cell carcinoma: favorable prognostic impact of TGF-ß1 mRNA expression in peripheral blood mononuclear cells.

Renal cell carcinoma (RCC) can inhibit protective immunity by induction of immunosuppressive cells that produce inhibitory cytokines such as interleukin (IL)-10 and transforming growth factor (TGF)-ß. If this immunosuppression influences response to kinase inhibitors such as sorafenib is not known. Therefore, we asked for the prognostic influence of cells with immunosuppressive properties in peripheral blood (pB) in a cohort of metastatic clear cell renal cell carcinoma (mRCC) patients uniformly receiving sorafenib treatment. IL-10 and TGF-ß mRNA levels, regulatory T-cell (Treg) counts, and frequencies of IL-10/TGF-ß producing mononuclear cell subsets were determined in pB from 46 patients with mRCC before receiving sorafenib treatment. Relationship between established clinical and laboratory prognostic factors and outcome were examined by univariate and multivariate Cox regression analysis. IL-10 and TGF-ß1 mRNA levels, and frequencies of CD4(+)CD25high/CD3(+) and CD4(+)CD25highFoxP3(+)/CD3(+)Treg cells were significantly higher in mRCC patients compared with healthy individuals. Monocytes were suggested as main producers of IL-10 and TGF-ß. In a multivariate analysis low ECOG score and-surprisingly-high TGF-ß1 mRNA levels were independently associated with favorable progression-free survival (P=0.005 and P=0.003, respectively) and overall survival (P=0.001 and P=0.039, respectively). In conclusion, mRCC is associated with an immunosuppressive phenotype in peripheral blood. The positive prognostic influence of high TGF-ß1 mRNA expression levels may reflect immune promoting functions of TGF-ß in combined activity with inflammatory cytokines.