Abstract B109: Epigenetic reprogramming of T-cells from metastatic melanoma patients enhances central memory and decreases Th2/Treg phenotypes

Immunotherapy strategies for the treatment of melanoma have achieved impressive clinical outcomes over the past decade. Response rates to checkpoint blockade by PD-1 and CTLA-4 antibodies range from 15-40%, while in adoptive cell therapy using tumor infiltrating lymphocytes (TILs), anti-tumor response is observed in approximately 50%. However, the need to improve immunotherapies is evident as the majority of patients are unresponsive to treatment. Dysfunctional T-cells are thought to contribute to failed responses to checkpoint inhibition. As such we sought to investigate the ability of drugs targeting the epigenetic regulatory machinery as a means to alter T-cell function(s) and improve the anti-melanoma response. Here we demonstrate that the HDAC6 selective inhibitor ACY1215 disrupts mTORC signaling pathways in T-cells obtained from melanoma patients. Phosphorylation of mTOR, RAPTOR and the downstream molecules AKT, SGK1, PKCa and S6K were reduced on CD4 and CD8 T-cells after ACY1215 in vitro treatment (p<0.05). The levels of the Th2 cytokines IL-4, IL-6, IL-10 generated by ACY1215-treated T-cells (p<0.05) were also decreased. Similar results were achieved with an SGK1 inhibitor, in agreement with published data demonstrating SGK1 as a regulator of Th2 polarization. Since the mTOR/RAPTOR complex is known to be involved in determining T regulatory (Treg) function, the effects of ACY1215 on Tregs were evaluated. Treatment in vitro with ACY1215 decreased phosphorylated mTOR and RAPTOR in Tregs, and reduced the levels of FOXP3. In a functional suppression assay, ACY1215-treated Tregs displayed a reduced ability to impair proliferation of effector T-cells (Teff) compared to control (DMSO: 10% vs ACY1215: 25% Teff proliferation, p<0.05). To explore whether HDAC inhibition during expansion of tumor infiltrating lymphocytes (TIL) for adoptive transfer would improve their quality and anti-tumor reactivity, TIL isolated from melanoma surgical biopsies were cultured in vitro with IL-2 and ACY1215. Treatment with ACY1215 led to an accumulation of central memory CD4 and CD8 TILs (p<0.01 and p<0.05, respectively), which was maintained even after rapid expansion with anti-CD3 and anti-CD28 stimulation in vitro. Similarly, ACY1215 treatment of T-cells derived from peripheral blood of melanoma patients and healthy donors also displayed an increased central memory phenotype, characterized by expression of CD45RO, CD62L and CCR7 (p<0.05). Inhibition of AKT has been shown to increase T-cells with memory characteristics, and the use of an AKT inhibitor also resulted in accumulation of central memory T-cells. Confirming the observed phenotypic changes, microarray analysis of ACY1215-treated TILs revealed up-regulation of genes associated with a T-cell central memory and inflammatory response (e.g. SELL, LEF1, TNFRSF9) and downregulation of genes associated with Treg function (e.g. LGMN, CXCL8). Collectively these data suggest that reprogramming T-cells with epigenetic modulators may improve melanoma immunotherapy by reducing Treg suppression and production of immunosuppressive cytokines, while favoring generation of central memory T-cells.

Citation Format: Andressa L. Sodre, David M. Woods, Amod Sarnaik, Brian C. Betts, Jeffrey S. Weber. Epigenetic reprogramming of T-cells from metastatic melanoma patients enhances central memory and decreases Th2/Treg phenotypes [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 B109.

Abstract A066: Histone deacetylase 11 is an epigenetic regulator of T-cell pro-inflammatory function and novel target for enhancing T-cell anti-tumor activity

The efficacy of immunotherapy is dependent on the ability of antigen-specific T-cells to mount a proper anti-tumor response while avoiding a plethora of immunosuppressive mechanisms. Unfortunately, these immunosuppressive mechanisms often overwhelm the T-cell response, resulting in patients failing to respond. Histone deacetylases (HDACs) are a family of epigenetic modifiers named for their ability to remove acetyl groups from lysine residues of histone tails, thereby regulating the chromatin structure and gene expression. Here we report that HDAC11, the most recently discovered HDAC, is a regulator of T-cell pro-inflammatory function. Previous reports have shown HDAC11 expression to be tissue restricted. Consequently, we compared expression levels of HDAC11 using an eGFP reporter mouse, in various immune cells. It was found that T-cells expressed relatively high levels of HDAC11. However, while resting T-cells, both central memory and naïve, had high levels of HDAC11 expression, effector or effector memory T-cells displayed lower levels. Additionally, T-cells experienced rapid down-regulation of HDAC11 upon activation. To expand upon these observations, the function of T-cells from HDAC11KO mice were investigated. Initial experiments revealed no gross changes in the numbers or maturation of T-cells. However, HDAC11KO mice displayed an increased percentage of central memory CD8+ T-cells (p<0.05). Additionally, upon activation these T-cells were more apt to acquire effector status (p<0.001). Upon activation, HDAC11KO T-cells demonstrated a robust increase in IL-2, TNF and IFNγ production (p<0.01), but showed no differences in Th2 or Th17 cytokine production. These T-cells also expressed higher levels of the effector molecules granzyme B and perforin (p<0.01). Moreover, post-activation, CD8+ T-cells lacking HDAC11 also displayed a higher percentage of proliferating cells, and more divisions of proliferating cells (p<0.01). HDAC11KO T-cells displayed higher resistance to proliferative suppression by Tregs and failed to succumb to anergy in a high dose antigen model. Indeed, while OTII T-cells from mice injected with high dose OVA peptide displayed reduced levels of IFNγ production compared to cells from non-injected mice after rechallenge, HDAC11KO/OTII T-cells had an increase in IFNγ production. Mechanistically, T-cells devoid of HDAC11 did not appear to have differences in TCR signaling, but did express higher levels of the transcription factors EOMES and T-bet. Chromatin immunoprecipitation (ChIP) revealed higher basal levels of acetylation of these genes in HDAC11KO mice. ChIP analysis also revealed interactions of HDAC11 at the promoters of both EOMES and T-bet. In a graft vs. host disease (GvHD) model, HDAC11KO T-cells produced a more rapid onset of GvHD, and were able to do so with transfers of cell numbers below that able to induce GvHD using WT T-cells (p<0.01). This GvHD was characterized by greater levels of IFNγ and TNF as well as increased T-cell expansion (p<0.05). In a B16 melanoma model, adoptive transfer of HDAC11KO T-cells resulted in delayed tumor progression (p<0.05) compared to WT T-cells. To begin investigating the clinical potential of these data, the expression levels of HDAC11 were investigated in melanoma tumor sections utilized to grow tumor infiltrating lymphocytes (TIL) for clinical trials of adoptive cell therapy. A reduced level of HDAC11 was found in tumor sections from those patients responding to TIL therapy compared to progressing patients (p<0.01). Collectively, beyond demonstrating HDAC11 as a novel epigenetic regulator of T-cell pro-inflammatory function, these results highlight HDAC11 as a novel target for enhancing the efficacy of immunotherapy.

Citation Format: David M. Woods, Andressa L. Sodre, Karrune Woan, Alejandro Villagra, Amod Sarnaik, Jeffrey Weber, Eduardo M. Sotomayor. Histone deacetylase 11 is an epigenetic regulator of T-cell pro-inflammatory function and novel target for enhancing T-cell anti-tumor activity. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A066.

Abstract 257: Class I HDAC inhibition upregulates PD-1 ligands in melanoma and increases the efficacy of PD-1 blockade

Ligation of co-inhibitory molecules such as PD-L1/PD-1 are known mechanisms of tumor escape. Blockade of this specific pathway with antibodies against PD-1 has proven effective in the treatment of metastatic melanoma, with response rates of 30-40% (Topalian, SL et al. 2012). However, since the majority of patients fail to respond, approaches to augment the efficacy of this approach are needed. We report herein that histone deacetylase (HDAC) inhibitors against class I HDACs generate robust and durable upregulation of PD-L1 and PD-L2 in melanoma cell lines as well as patient tumor samples. Combining the HDAC inhibitor LBH589 with PD-1 blockade in a murine melanoma model results in delayed tumor growth and increased survival, superior to either single agent. Initially, we evaluated the expression of PD-L1 by flow cytometry on several melanoma cell lines treated with the HDAC inhibitors LBH589, MS275 and MGCD0103. At 72 hours, all treatments resulted in increased PD-L1 surface expression. As a follow-up, additional inhibitors and time points were assessed. Upregulation was seen at 24 hours after treatment and continued past 96 hours. However, these effects were not observed with HDAC6 or class IIa specific inhibitors. We then evaluated a larger panel of HDACi on several patient derived melanomas. We observed dose dependent upregulation with all inhibitors with inhibition of HDAC1, HDAC2 and/or HDAC3, but no impact of HDAC6, HDAC8 or class IIa specific inhibitors. Additionally, we observed low level, but consistent upregulation of PD-L2 in conjunction with PD-L1. These in vitro results were validated in vivo using a B16 murine melanoma model and patient xenografts in SCID mice. Chromatin immunoprecipitation analysis shows that treatment of melanoma with an HDAC inhibitor results in increased histone acetylation at the PD-L1 promoter. Previous studies have demonstrated PD-L1 regulation by STAT3 (Wolfle SJ et al. 2011), in addition to HDAC inhibitor alteration of STAT3 activation (Gupta M. et al 2012). We are currently evaluating alterations in STAT3 signaling in HDAC inhibitor treated melanoma. Given the anti-melanoma properties of LBH589 and its augmentation of immunogenicity previously reported by our group, combination therapy using PD-1 blocking antibodies with LBH589 was explored. Treatment of B16 melanoma-bearing C57BL/6 mice with the combination resulted in tumor progression delay (p = 0.01) compared to control and single agent treatments. Accompanying this tumor delay was an increase in overall survival (p = 0.03). These results highlight the ability of epigenetic modifying agents to augment immunogenicity and increase the efficacy of current immunotherapies. These results provide a strong rationale for combining LBH589 with PD-1 blockade for the treatment of metastatic melanoma.

Citation Format: David M. Woods, Andressa L. Sodre, Amod Sarnaik, Eduardo M. Sotomayor, Jeffrey Weber. Class I HDAC inhibition upregulates PD-1 ligands in melanoma and increases the efficacy of PD-1 blockade. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 257. doi:10.1158/1538-7445.AM2015-257

Abstract 643: The histone deacetylase inhibitor Quisinostat augments the anti-tumor reponses of T-cells: Implications in adoptive cell therapy

It has become increasingly clear that histone deacetylases (HDACs), a family of epigenetic modifiers, play intimate roles in both tumor and immune biology. Indeed, two HDAC inhibitors (HDACi) are FDA approved for the treatment of cutaneous T-cell leukemia, and various others are currently undergoing clinical trials for the treatment of both solid and hematological malignancies. Beyond direct anti-tumor effects, HDACi have shown pronounced abilities to augment the immunogenicity of tumor cells leading to an improved ant-tumor immune response. Furthermore, in addition to anti-tumor effects, several studies have demonstrated a profound ability of HDACi to tip the scale between tolerance and inflammation in antigen presenting cells, leading to enhanced T-cell activation. However, less well studied is the ability of HDACi to directly influence the function and fate of T-cells. Here we report that the HDACi JNJ-264-81585 (Quisinostat) is able to augment the pro-inflammatory phenotype of T-cells in vitro and in vivo. Quisinostat is a hydroxamic acid with potent sub-nanomolar inhibition of several HDACs, and reported anti-tumor activity. Here we report that Quisinostat has a potent HDAC inhibition in T-cells, with sub-nanomolar doses increasing histone 3 acetylation levels in a dose dependent manner. Intriguingly, when treated with Quisinostat in vitro, activated murine CD4+ and CD8+ T-cells produced significantly higher levels of the pro-inflammatory cytokines IL-2, IFN-g, and TNF. Concomitantly, treated T-cells produced decreased levels of IL-6 and IL-17. To determine the efficacy of Quisinostat at augmenting T-cell function in vivo, a novel T-cell adoptive transfer model was utilized. In this model syngeneic T-cells from B6.SJL mice were stained with the proliferation tracking dye CellTrace™ Violet and activated in the presence of Quisinostat, then subsequently adoptively transferred into sub-lethally irradiated C57BL/6 recipient mice. Analysis of proliferation of transferred T-cells showed that CD8+ T-cells treated with Quisinostat had significantly higher rates of proliferation than those treated with DMSO control. As well, in a result similar to that seen in vitro, adoptively transferred T-cells had skewing towards a predominantly CD8+ composition. Finally, T-cells treated with Quisinostat displayed a reconstitution advantage over DMSO treated cells, with higher percentages of transferred T-cells relative to endogenous T-cells. Collectively, these results demonstrate a profound and important ability of HDAC inhibition to modulate the T-cell response, highlighting a role of HDACi, particularly Quisinostat, in augmenting the efficacy of adoptive cell therapy, giving rationale for clinical investigation.

Citation Format: David M. Woods, Andressa L. Sodre, Jason B. Brayer, Eduardo M. Sotomayor. The histone deacetylase inhibitor Quisinostat augments the anti-tumor reponses of T-cells: Implications in adoptive cell therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 643. doi:10.1158/1538-7445.AM2014-643

Abstract 4090: Inhibition of class I histone deacetylases promotes robust and durable enhancement of PDL1 expression in melanoma: Rationale for combination therapy

Histone deacetylase inhibitors (HDACi) have shown remarkable anti-tumor activity, leading to FDA approval of two HDACi for the treatment of CTCL and several others currently at various stages of clinical development for the treatment of both solid and hematological malignancies. Previous work from our lab has shown that treatment with HDACi results in increased expression of pro-inflammatory promoting surface markers on melanoma cells, promoting enhanced T-cell activation. Recent clinical trial data has shown that blockade of the PD1/PDL1 interaction is effective in the treatment of melanoma, renal cell and non-small cell lung cancer. Importantly, responses to PD1 blocking antibodies were preferentially seen in patients with tumors expressing PDL1. Here we report that HDACi targeting class I HDACs, but not class II, augments expression of PDL1 in melanoma cells. Two murine and five human melanoma cell lines were treated for up to 72 hours with DMSO, LBH589 (pan-HDACi), MS275 (class I inhibitor), MGCD0103 (class I inhibitor), an HDAC6 specific inhibitor, or a class IIa inhibitor. Using flow cytometry, dose dependent, increases in PDL1 expression were found in the LBH589, MS275 and MGCD0103 treated groups, but not in those receiving HDAC6i or class IIa inhibitor, relative to DMSO. Increased expression was noted as early as 24 hours after treatment and peaked at 72 to 96 hours post-treatment. As IFN-γ is known to upregulate the expression of PDL1 in both normal and transformed cells, we evaluated whether these results were associated with induction of IFN-γ expression by the melanoma cells. However, no detectable levels of IFN-γ were seen in either non-treated, class I HDACi, or class II HDACi-treated cells. Melanoma cells treated with HDACi in addition to IFN-γ have enhanced expression of PDL1 relative to either treatment alone. To further gain insight into the specific HDAC regulating the expression of PDL1, preliminary experiments utilizing knockdowns (KD) of individual class I HDACs were performed. In all KD melanoma cells no increase in PDL1 expression was seen, suggesting that the increased expression of PDL1 is dependent on inhibition of multiple class I HDACs. Supporting this conclusion, treatment of class I HDAC-KDs with HDACi recapitulates the increased PDL1 expression seen with WT melanoma. Finally, in preliminary in vivo experiments combining treatment of melanoma bearing mice with anti-PDL1 antibodies, mice receiving the combination treatment had a survival advantage over those receiving PDL1 blocking antibodies or HDACi alone. These results provide a strong rationale for the evaluation of combination therapies utilizing PDL1 or PD1 blocking antibodies in combination with HDACi. Furthermore, these results support the need for further development and investigation of iso-specific HDACi in order to obtain more directed therapeutic efficacy.

Citation Format: David M. Woods, Andressa L. Sodre, Eva Sahakian, John Powers, Maritza Lienlaf-Moreno, Patricio Perez-Villarroel, Alejandro Villagra, Javier Pinilla-Ibarz, Eduardo Sotomayor. Inhibition of class I histone deacetylases promotes robust and durable enhancement of PDL1 expression in melanoma: Rationale for combination therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4090. doi:10.1158/1538-7445.AM2014-4090

Histone deacetylase 11: A novel epigenetic regulator of myeloid derived suppressor cell expansion and function

Myeloid-derived suppressor cells (MDSCs), a heterogeneous population of cells capable of suppressing anti-tumor T cell function in the tumor microenvironment, represent an imposing obstacle in the development of cancer immunotherapeutics. Thus, identifying elements essential to the development and perpetuation of these cells will undoubtedly improve our ability to circumvent their suppressive impact. HDAC11 has emerged as a key regulator of IL-10 gene expression in myeloid cells, suggesting that this may represent an important targetable axis through which to dampen MDSC formation. Using a murine transgenic reporter model system where eGFP expression is controlled by the HDAC11 promoter (Tg-HDAC11-eGFP), we provide evidence that HDAC11 appears to function as a negative regulator of MDSC expansion/function in vivo. MDSCs isolated from EL4 tumor-bearing Tg-HDAC11-eGFP display high expression of eGFP, indicative of HDAC11 transcriptional activation at steady state. In striking contrast, immature myeloid cells in tumor-bearing mice display a diminished eGFP expression, implying that the transition of IMC to MDSC's require a decrease in the expression of HDAC11, where we postulate that it acts as a gate-keeper of myeloid differentiation. Indeed, tumor-bearing HDAC11-knockout mice (HDAC11-KO) demonstrate a more suppressive MDSC population as compared to wild-type (WT) tumor-bearing control. Notably, the HDAC11-KO tumor-bearing mice exhibit enhanced tumor growth kinetics when compare to the WT control mice. Thus, through a better understanding of this previously unknown role of HDAC11 in MDSC expansion and function, rational development of targeted epigenetic modifiers may allow us to thwart a powerful barrier to efficacious immunotherapies.