Soluble immune checkpoints and T-cell subsets in blood as biomarkers for resistance to immunotherapy in melanoma patients

Different mechanisms lead to immune checkpoint inhibitor (ICI) resistance. Identifying clinically useful biomarkers might improve drug selection and patients’ therapy. We analyzed the soluble immune checkpoints sPD1, sPDL1, sLAG3, and sTIM3 using ELISA and their expression on circulating T cells using FACS in pre- and on-treatment blood samples of ICI treated melanoma patients. In addition, pre-treatment melanoma metastases were stained for TIM3 and LAG3 expression by IHC. Results were correlated with treatment response and progression-free survival (PFS). Resistance to anti-PD1 treatment (n = 48) was associated with high pre-treatment serum levels of sLAG3 (DCR: p = .009; PFS: p = .018; ROC cutoff >148 pg/ml) but not sPD1, sPDL1 or sTIM3. In contrast, resistance to ipilimumab plus nivolumab (n = 42) was associated with high levels of sPD1 (DCR: p = .019, PFS: p = .046; ROC cutoff >167 pg/ml) but not sPDL1, sLAG3 or sTIM3. Both treatment regimens shared a profound increase of sPD1 serum levels with treatment (p < .0001). FACS analysis revealed reduced frequencies of CD3+ CD8+ PD1 + T cells (p = .028) in anti-PD1-resistant patients, whereas increased frequencies of CD3+ CD4+ LAG3 + T cells characterized patients resistant to ipilimumab plus nivolumab (p = .033). Unlike anti-PD1 monotherapy, combination blockade significantly increased proliferating T cells (CD3+ CD8+ Ki67 + T cells; p < .0001) and eosinophils (p = .001). In melanoma metastases, an increased infiltration with TIM3+ or LAG3 + T cells in the tumor microenvironment correlated with a shorter PFS under anti-PD1 treatment (TIM3: p = .019, LAG3: p = .07). Different soluble immune checkpoints characterized checkpoint inhibitor-resistant melanoma. Measuring these serum markers may have the potential to be used in clinical routine.

CCR5 status and metastatic progression in colorectal cancer

Multiple reports have highlighted the importance of the local immunological cellular composition (i.e. the density of effector T cells and macrophage polarization state) in predicting clinical outcome in advanced metastatic stage of colorectal cancer. However, in spite of the general association between a high effector T cell density and improved outcome, our recent work has revealed a specific lymphocyte-driven cancer cell-supporting signal. Indeed, lymphocyte-derived CCL5 supports CCR5-positive tumor cell proliferation and thereby fosters tumor growth in metastatic liver lesions. Upon systematic analysis of CCR5 expression by tumor cells using immunohistochemistry, we observed that the intensity of CCR5 increases with primary tumor size and peaks in T4 tumors. In liver metastases however, though CCR5 expression intensity is globally heightened compared to primary tumors, alterations in the expression patterns appear, leading to “patchiness” of the stain. CCR5 patchiness is, therefore, a signature of liver metastases in our cohort (n = 97 specimens) and relates to globally decreased expression intensity, but does not influence the extent of the response to CCR5 inhibitor Maraviroc in patients. Moreover, CCR5 patchiness relates to a poor immune landscape characterized by a low cytotoxic-to-regulatory T cell ratio at the invasive margin and enriched cellular and molecular markers of macrophage M2 polarization. Finally, because higher numbers of PD-1- and CTLA-4-positive cells surround tumors with patchy CCR5 expression, one can speculate that these tumors potentially respond to immune checkpoint blockade. This hypothesis is corroborated by the prolonged disease-free survival and disease-specific survival observed in patients with low gene expression of CCR5 in metastases from two publically available cohorts. These observations highlight the complex role of the CCL5-CCR5 axis in CRC metastatic progression and warrant further investigations.

Abstract B054: Evaluation of NY-BR-1 as a suitable antigen for CAR based immunotherapy

Despite the tremendous clinical success of CAR-T-cell therapy in leukemia, translation of this treatment option to solid tumors still remains challenging. Off-target toxicity of CAR-T-cells against low-level antigen expressing healthy tissue is considered to be the most dangerous scenario when treating cancer patients yielding eventually to at least one reported fatal SAE. To avoid such fatalities a straight assessment of target antigen expression including all known isoforms of the respective protein in tumors as well as healthy tissues must be performed before drug application. The breast differentiation antigen NY-BR-1 (ANKRD30A) is known to serve as a perfect antigen for active immunotherapy of female breast cancer due to absence of expression in any female healthy tissue except for mammary gland. Here we report on the critical evaluation of NY-BR-1 as a target antigen for CAR-T-cells using bioinformatics, staining procedures and functional CAR tests. While bioinformatic analyses and stainings using the anti-NY-BR-1 monoclonal antibody “clone2” confirmed previous findings, we observed different results when the respective “clone2 scFv” was used. This construct not only shows a higher binding capacity to NY-BR-1 but also a modest but detectable binding to the isoform NY-BR1.1 (ANKRD30B). Additionally, a CAR-construct based on “clone2 scFv” yielded into a cross-reactivity of T cells against NY-BR1.1. Due to the known expression of NY-BR1.1 in normal brain tissue in combination with the also known ability of CAR-T-cells to cross the blood brain barrier, the use of a “clone2 CAR” for the treatment of advanced breast cancer must be judged as dangerous. Our findings show that a critical evaluation of a candidate target antigen for CAR therapy shall be performed by the use of the respective scFv rather than the classical mAb approach.

Citation Format: Patrick Schmidt, Claudia Luckner Minden, Claudia Ziegelmeier, Isabella Gosch, Niels Halama, Frank Momburg, Rosa Eurich, Sarah Schott, Frederik Marmé, Andreas Schneeweiß, Claus Peter Heußel, Dirk Jäger, Inka Zörnig. Evaluation of NY-BR-1 as a suitable antigen for CAR based immunotherapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B054.

Opposite effects of transforming growth factor-β1 and vascular endothelial growth factor on the degeneration of aortic valvular interstitial cell are modified by the extracellular matrix protein fibronectin: implications for heart valve engineering

The enhancement of valvular interstitial cell (VIC) calcification by transforming growth factor-β1 (TGF-β1) and the endothelial inducing effect of vascular endothelial growth factor (VEGF) have been demonstrated. Here we report the modulating properties of extracellular matrix (ECM) modification on VIC calcification in the presence of TGF-β1 and VEGF. Ovine aortic VICs cultured on collagen, fibronectin, laminin, or uncoated surfaces were exposed to TGF-β1, VEGF, or left untreated. VEGF significantly inhibited the formation of calcific nodules independent of ECM Protein coating (p < 0.05). TGF-β1 exposition resulted in the formation of calcific nodules on collagen, laminin, and uncoated control surfaces. In contrast, fibronectin coating resulted in significantly reduced nodule formation despite TGF-β1 administration. Further, we showed a marked increase of apoptotic and dead cells in calcific nodules. Overall, our data demonstrate that, an additive protective effect on VICs can be achieved by providing specific growth factors or a specific ECM environment. Here, VEGF administration inhibited calcification and apoptosis, particularly in combination with fibronectin coating. This combination appears to be a promising tool for modification of heart valve scaffolds for tissue engineering purposes and preclinical trials.

[Age-dependent DNA-content of brain, testis and ovar in men and rats (author's transl)]

The DNA-content of brain, testis and ovar of Wistar rats (inbred strain) was quantitatively analysed. We observed no significant differences between the several parts of the cerebrum, but between the cerebrum and the cerebellum. Furthermore we demonstrated alterations (with increase and decrease) of the DNA content of all brain parts as well as of testis and ovar during the course of life of this Wistar rat strain. These results and further investigations of the water content as well as of the absolute and of the relative weight of brains of these rats (in comparison to humans) extend the data and our knowledge about these subjects. It is possible to differentiate growth phases (by means of the DNA assays, which correlate with the morphologically well defined growth phases. Finally these results are fundamentals and presuppositions for investigations of the production metabolism of these organs because the DNA content is a better parameter (reference or relation figure, resp.) than the dry or wet weights and the protein or the nitrogen contents.

[Contribution to wet and dry weights of mesenchymal and parenchymatous organs of humans and rats during the course of life (author's transl)]

The wet and dry weights of parenchymatous (lung, heart, liver, kidney) and of mesenchymal organs (aorta, skin, xiphoid cartilage) of humans and rats (both sexes) were investigated during the course of life. Furthermore, these investigations were done on the following rat organs: brain (divided in cerebrum as well as in cerebellum plus pons), spleen, rib cartilage, testis and ovar. The water content of these tissues and organs of both species was calculated by means of their wet and dry weights. The dry weights of the investigated parenchymal and mesenchymal organs of both species remain constant during the whole course of life (pastly until the high senile age)--using freeze-drying. The same is true for the water content: constancy without significant decrease during the investigated life periods and without sex dependent differences.