Abstract 2875: Evidence of immunosuppression in patients with breast ductal carcinoma in situ

Introduction: Ductal carcinoma in situ (DCIS) is a noninvasive precursor to invasive breast cancer. Although not all DCISlesions progress to cancer, most DCIS are treated as early breast cancer, given the uncertainty of which lesions will progress. The current increase in the incidence of DCIS has sparked interest in the immune contexture of the DCIS lesions as well as the immune status of DCIS patients, as a means to predict which DCIS lesions will progress to cancer. Studies done so far in invasive breast cancer showed that the immune system can mediate both tumor-promoting influence (via T regulatory (Treg) cells, M2 macrophages, myeloid-derived suppressor cells (MDSCs)), as well as tumor-suppressing influences (via CD8+ and CD4+ effector T cells, natural killer cells (NK), M1 macrophages, tissue-resident memory T (Trm) cells, B cell and dendritic (DCs) cells). Similar studies are still lacking in DCIS. Our aim was to start closing the gap in our understanding of the DCIS immune microenvironment, which will pave the way for novel preventative and therapeutic strategy.

Methods: We analyzed by flow cytometry peripheral blood mononuclear cells (PBMCs) from newly diagnosed DCIS patients for the presence of various immune cell types expressing specific phenotypic markers of immune effectors or immune suppressors and compared them with PBMC from age-matched healthy individuals.

Results: We found a statistically significant increase in the frequency of FoxP3+ regulatory T cells in DCIS PBMC compared with healthy controls. There was also a significant increase in Tim-3+CD8+ T effector memory cells (P= 0.035) and Tim-3+ CD8+ NKT cells (P = 0.033) in the PBMCs of patients with DCIS compared with healthy controls. T cells expressing other exhaustion markers, such as PD-1+ and LAG-3+ were present at very low levels in both groups.

Conclusion: Our results suggest that some of the many immunosuppressive mechanisms seen in patients with invasive breast cancer, such as regulatory T cells, are already present in pre-cancer DCIS. Evidence of the beginning of immune suppression is also reflected in the increased frequency of CD4+ and CD8+ T cells expressing the exhaustion marker Tim-3.

Citation Format: Sedigheh Taghinezhad-S, Amir Hossein Mohseni, Pamela L. Beatty, Leisha A. Emens, Olivera J. Finn. Evidence of immunosuppression in patients with breast ductal carcinoma in situ [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2875.

Altered Expression of the Epithelial Mucin MUC1 Accompanies Endoscopic Recurrence of Postoperative Crohn's Disease

BACKGROUND

MUC1-glycoprotein is expressed at low levels and in fully glycosylated form on epithelial cells. Inflammation causes MUC1 overexpression and hypoglycosylation. We hypothesized that overexpression of hypoglycosylated MUC1 would be found in postoperative Crohn's disease (CD) recurrence and could be considered an additional biomarker of recurrence severity.

METHODS

We examined archived neo-terminal ileum biopsies from patients with prior ileocecal resection who had postoperative endoscopic assessment of CD recurrence and given a Rutgeerts ileal recurrence score. Consecutive tissue sections were stained using 2 different anti-MUC1 antibodies, HMPV that recognizes all forms of MUC1 and 4H5 that recognizes only inflammation-associated hypoglycosylated MUC1.

RESULTS

A total of 71 postoperative CD patients were evaluated. There was significant increase in MUC1 expression of both glycosylated/normal (P<0.0001) and hypoglycosylated/abnormal (P<0.0001) forms in patients with severe endoscopic CD recurrence (i3+i4), ileal score i2, compared with patients in endoscopic remission (i0+i1). Results were similar regardless of anti-TNF-α use. Although MUC1 expression and Rutgeerts scores were in agreement when characterizing the majority of cases, there were a few exceptions where MUC1 expression was characteristic of more severe recurrence than implied by Rutgeerts score.

CONCLUSIONS

MUC1 is overexpressed and hypoglycosylated in neo-terminal ileum tissue of patients with postoperative CD recurrence. Increased levels are associated with more severe endoscopic recurrence scores, and this is not influenced by anti-TNF-α use. Discrepancies found between Rutgeerts scores and MUC1 expression suggest that addition of MUC1 as a biomarker of severity of postoperative CD recurrence may improve categorization of recurrence status and consequently treatment decisions.

Myeloid derived suppressor cells in cancer, premalignancy and inflammation: A roadmap to cancer immunoprevention

The ultimate success of any form of cancer therapy or cancer prevention depends on its ability to engage the power of the immune system to completely eliminate a growing tumor, lower the life-time tumor risk and establish long-term memory to prevent recurrence or future tumors. For that reason, all therapies but especially immunotherapies depend on the immune health (immunocompetence) of each treated individual. Cancer and chronic illnesses, combined with a usually more advanced age of cancer patients or those at risk for cancer are known to severely suppress multiple antitumor functions of the immune system. Understanding the critical mechanisms controlling and mediating immune suppression can lead to additional therapies to alleviate the effects of those mechanisms and improve the outcome of cancer therapy and prevention. We introduce and review here a highly immunosuppressive cell population found in cancer, precancer, and chronic inflammatory diseases, myeloid derived suppressor cells (MDSC). First described in the setting of advanced cancer, their presence and immunosuppressive activity has been seen more recently in early premalignant lesions and in chronic inflammatory diseases leading to cancer. We describe the detrimental effects of their presence on cancer immunotherapy, immunosurveillance and immunoprevention and review early attempts to develop drugs to eliminate them or reduce their negative impact.

Circulating Myeloid Derived Suppressor Cells (MDSC) That Accumulate in Premalignancy Share Phenotypic and Functional Characteristics With MDSC in Cancer

Myeloid derived suppressor cells (MDSC) are a heterogeneous population of immature myeloid cells that accumulate in circulation of cancer patients and at tumor sites where they suppress anti-tumor immunity. We previously reported that in a colon cancer prevention trial of a MUC1 vaccine tested in individuals at increased risk for colon cancer, those who did not mount immune response to the vaccine had higher pre-vaccination levels of circulating MDSC compared to those who did. We also reported that individuals with pancreatic premalignancy, Intraductal Papillary Mucinous Neoplasm (IPMN), had increased circulating levels of MDSC that inversely correlated with spontaneous antibody responses against the pancreatic tumor associated antigen MUC1, abnormally expressed on IPMN. Accumulation of MDSC in cancer and their immunosuppressive role had been well established but their presence in premalignancy was unexpected. In this study we compared MDSC in premalignancy with those in cancer with the hypothesis that there might be differences in the composition of various MDSC subpopulations and their immunosuppressive functions due to different lengths of exposure to disease and/or different tissue microenvironments. In cohorts of patients with premalignant polyps, colon cancer, premalignant IPMN, and pancreatic cancer, we confirmed higher levels of MDSC in premalignancy compared to healthy controls, higher levels of MDSC in cancer compared to premalignancy, but no difference in their subpopulation composition or immunosuppressive capacity. We show that levels of MDSC in premalignancy correlate negatively in vivo with spontaneous MUC1-specific antibody responses and in vitro with polyclonal T cell proliferation and IFN-γ secretion.

Abstract LB-305: Randomized, double-blind, placebo-controlled immunoprevention trial with MUC1 vaccine in patients with newly diagnosed advanced adenomas

Background: Immunotherapy targeting tumor-associated antigens aberrantly expressed on colorectal cancers and adenomatous polyps offers the potential for a relatively non-invasive and non-toxic prevention strategy, and because of the specificity of the immune response and its long-term memory, the potential for prolonged protection. In a double-blind randomized trial in patients with a diagnosis of advanced colorectal adenomas within the previous year, we are evaluating MUC1 vaccine with the TLR-3 agonist polyICLC (Hiltonol®) as an adjuvant, for its immunogenicity and effect on colorectal adenoma recurrence at follow up colonoscopy.

Aim: We report on a primary endpoint, MUC1 immunogenicity at week 12 (following vaccine or placebo administration at 0, 2, and 10 weeks), and on determinants of the immune response and vaccine toxicity.

Methods: Subjects with an advanced adenoma (defined as ≥1cm, tubulovillous or villous histology, or with HGD) were randomized. Response to the vaccine was assessed by monitoring IgG anti-MUC1 antibody titer ratio; defined as t12/t0, where t0 is the initial titer measured prior to vaccination, and t12 is the titer drawn at 12 weeks. A ratio of 2.0 was used as the primary definition of a significant immune response. T Regulatory and myleoid derived suppressor cell (MDSC) levels at baseline were assessed in relation to vaccine response. Adverse events (AEs) were recorded according to NCI Common Terminology Criteria for Adverse Events (CTCAE) version 4.0.

Results: 102 subjects were randomized at 6 centers, 52 received MUC1 vaccine and 50 placebo. Subjects had a mean age of 59.4±7.0 (range 40-70) years, 60.8% were male, 88.2% were white, and 18.6% Hispanic or Latino. At 12 weeks the IgG ratio was ≥2.0 in 13/52 (25%) of patients receiving vaccine (ratio range 2.9-17.3), vs. 0/50 in placebo group (P=.0001), and was

≥1.5 in 19/52 (36.5%) of patients receiving vaccine compared to 1/50 (2%) in placebo group (P&lt;.0001). In the vaccinated group, the IgG ratio was ≥2.0 in 45% of women (9/20) vs. 12.5% of men (4/32) (P=0.009) and ≥1.5 in 55% of women (11/20) vs. 25% of men (8/32) (P=0.03). In the vaccinated group, reduced levels of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) pre-vaccination were associated with response, 0.2±0.1 among responders (n=13) vs. 0.8±1.1 among non-responders (N=39) (p=0.0006) whereas monocytic MDSC and T regulatory cells (CD4+CD25, Foxp3) were not. There were no grade 3 adverse events (AE) possibly or probably related to the vaccine. The most common AE was an injection site reaction (grade 1 or 2) which occurred in 80.8% (n=42/52) in vaccine group vs. 6.0% in the placebo group (3/50).

Conclusions: Subjects with an advanced adenoma receiving MUC1 vaccine compared with a placebo are significantly more likely to develop an anti-IgG MUC1 immune response at 12 weeks. Women and subjects with lower circulating PMN-MDSC levels at baseline were more likely to respond. The vaccine was well tolerated. Follow up for the effect of the vaccine on adenomatous polyp recurrence is ongoing.

Citation Format: Robert E. Schoen, Lisa A. Boardman, Marcia Cruz-Correa, Ajay Bansal, Pamela L. Beatty, David Kastenberg, Chin Hur, Lynda Dzubinski, Luz Rodriguez, Andres Salazar, John McKolanis, Drew Seisler, Nathan R. Foster, May-Yin Polley, Paul J. Limburg, Olivera J. Finn. Randomized, double-blind, placebo-controlled immunoprevention trial with MUC1 vaccine in patients with newly diagnosed advanced adenomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-305.

Abnormally glycosylated MUC1 establishes a positive feedback circuit of inflammatory cytokines, mediated by NF-κB p65 and EzH2, in colitis-associated cancer

The abnormal hypoglycosylated form of the epithelial mucin MUC1 is over-expressed in chronic inflammation and on human adenocarcinomas, suggesting its potential role in inflammation-driven tumorigenesis. The presence of human MUC1 aggravates colonic inflammation and increases tumor initiation and progression in an in vivo AOM/DSS mouse model of colitis-associated cancer (CAC). High expression levels of pro-inflammatory cytokines, including TNF-α and IL-6, were found in MUC1+ inflamed colon tissues. Exogenous TNF-α promoted the transcriptional activity of MUC1 as well as over-expression of its hypoglycosylated form in intestinal epithelial cells (IECs). In turn, hypoglycosylated MUC1 in IECs associated with p65 and up-regulated the expression of NF-κB-target genes encoding pro-inflammatory cytokines. Intestinal chronic inflammation also increased the expression of histone methyltransferase Enhancer of Zeste protein-2 (EzH2) and its interaction with cytokine promoters. Consequently, EzH2 was a positive regulator of MUC1 and p65-mediated IL-6 and TNF-α gene expression, and this function was not dependent on its canonical histone H3K27 methyltransferase activity. Our findings provide a mechanistic basis for already known tumorigenic role of the hypoglycosylated MUC1 in CAC, involving a transcriptional positive feedback loop of pro-inflammatory cytokines.

Immunobiology and immunosurveillance in patients with intraductal papillary mucinous neoplasms (IPMNs), premalignant precursors of pancreatic adenocarcinomas

Premalignant lesions for many cancers have been identified, and efforts are currently directed toward identification of antigens expressed on these lesions that would provide suitable targets for vaccines for cancer prevention. Intraductal papillary mucinous neoplasms (IPMNs) are premalignant pancreatic cysts of which a subset has the potential to progress to cancer. Currently, there are no validated predictive markers for progression to malignancy. We hypothesized that the presence or absence of immune surveillance of these lesions would be one such factor. Here we show that the tumor antigen MUC1, which is abnormally expressed on pancreatic cancer and is a target for cancer immunosurveillance, is also abnormally expressed on premalignant IPMN. We show that some IPMN patients make MUC1-specific IgG. Moreover, we show evidence of CD4 and CD8 T cell infiltration into IPMN areas of high dysplasia suggesting an ongoing immune response within the lesions. We also found, however, increased levels of circulating myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) in some IPMN patients as well as evidence of T cell exhaustion. Further studies correlating immunosurveillance or immunosuppression with IPMN progression to malignancy will help define the immune response as a biomarker of risk, leading potentially to a vaccine to boost spontaneous immunity and prevent progression to cancer.

Cancer immunoprevention

Cancer immunotherapy is now a reality. The results are phenomenal but the cost is outrageous. Even if the cost eventually comes down and immunotherapy becomes more broadly available, using the knowledge derived from immunotherapy to apply to immunoprevention would be a good strategy. The most likely approach to cancer immunoprevention is cancer vaccines. To date, cancer vaccines have been tested mostly in the setting of advanced disease. Numerous immunosuppressive mechanisms have been identified in the tumor microenvironment as well as systemically that compromise the ability of cancer patients to respond to the vaccines. Multiple approaches are being tested to improve therapeutic cancer vaccine efficacy, including combinations with other immunotherapies. An alternative approach is to administer the vaccines to individuals without cancer but at high risk for cancer. Data in support of this approach and immunoprevention in general is accumulating and clinical testing has started.

Influenza virus infection elicits protective antibodies and T cells specific for host cell antigens also expressed as tumor-associated antigens: a new view of cancer immunosurveillance

Most tumor-associated antigens (TAA) are self-molecules that are abnormally expressed in cancer cells and become targets of antitumor immune responses. Antibodies and T cells specific for some TAAs have been found in healthy individuals and are associated with lowered lifetime risk for developing cancer. Lower risk for cancer has also been associated with a history of febrile viral diseases. We hypothesized that virus infections could lead to transient expression of abnormal forms of self-molecules, some of which are TAAs; facilitated by the adjuvant effects of infection and inflammation, these molecules could elicit specific antibodies, T cells, and lasting immune memory simultaneously with immunity against viral antigens. Such infection-induced immune memory for TAA would be expected to provide life-long immune surveillance of cancer. Using influenza virus infection in mice as a model system, we tested this hypothesis and demonstrated that influenza-experienced mice control 3LL mouse lung tumor challenge better than infection-naive control mice. Using 2D-difference gel electrophoresis and mass spectrometry, we identified numerous molecules, some of which are known TAAs, on the 3LL tumor cells recognized by antibodies elicited by two successive influenza infections. We studied in detail immune responses against glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone H4, HSP90, malate dehydrogenase 2, and annexin A2, all of which were overexpressed in influenza-infected lungs and in tumor cells. Finally, we show that immune responses generated through vaccination against peptides derived from these antigens correlated with improved tumor control.

Preventing cancer by targeting abnormally expressed self-antigens: MUC1 vaccines for prevention of epithelial adenocarcinomas

Prophylactic vaccines based on tumor-associated antigens (TAAs) have elicited concerns due to their potential toxicity. Because TAAs are considered self-antigens, the prediction is that such vaccines will induce autoimmunity. While this has been observed in melanoma, where an antitumor immune response leads to vitiligo, autoimmunity has almost never been seen following vaccination with numerous other TAAs. We hypothesized that antigen choice determines outcome and have been working to identify TAAs whose expression differs between normal and tumor tissue, and thus could elicit antitumor immunity without autoimmunity. Studies on the epithelial TAA MUC1 have revealed that, compared to MUC1 on normal cells, tumors, premalignant lesions, and noncancerous pathologies affecting epithelial cells express abnormal MUC1, which is not a self-antigen but rather an abnormal disease-associated antigen (DAA). This distinction, which can be made for many known TAAs, has broad implications for the design and acceptance of preventative cancer vaccines.

Tumor immunology: basic and clinical advances

The third in a series of AACR conferences, entitled "Tumor Immunology: Basic and Clinical Advances," was held in Miami Beach, Florida from November 30 to December 3, 2010. The overall objective of this meeting was to discuss rapid developments in the understanding of basic principles of antitumor immunity and strategies for increasing the success rate of cancer immunotherapy. The key findings that emerged from the meeting included (i) that integrated approaches are required for the development of effective cancer immunotherapies and (ii) attention should be on multiple cellular and molecular components and their broader networks rather than on a single pathway or cell type.

Vaccine against MUC1 antigen expressed in inflammatory bowel disease and cancer lessens colonic inflammation and prevents progression to colitis-associated colon cancer

Association of chronic inflammation with an increased risk of cancer is well established, but the contributions of innate versus adaptive immunity are not fully delineated. There has furthermore been little consideration of the role played by chronic inflammation-associated antigens, including cancer antigens, and the possibility of using them as vaccines to lower the cancer risk. We studied the human tumor antigen MUC1 which is abnormally expressed in colon cancers and also in inflammatory bowel disease (IBD) that gives rise to colitis-associated colon cancer (CACC). Using our new mouse model of MUC1(+) IBD that progresses to CACC, interleukin-10 knockout mice crossed with MUC1 transgenic mice, we show that vaccination against MUC1 delays IBD and prevents progression to CACC. One mechanism is the induction of MUC1-specific adaptive immunity (anti-MUC1 IgG and anti-MUC1 CTL), which seems to eliminate abnormal MUC1(+) cells in IBD colons. The other mechanism is the change in the local and the systemic microenvironments. Compared with IBD in vaccinated mice, IBD in control mice is dominated by larger numbers of neutrophils in the colon and myeloid-derived suppressor cells in the spleen, which can compromise adaptive immunity and facilitate tumor growth. This suggests that the tumor-promoting microenvironment of chronic inflammation can be converted to a tumor-inhibiting environment by increasing adaptive immunity against a disease-associated antigen.

Cutting edge: transgenic expression of human MUC1 in IL-10-/- mice accelerates inflammatory bowel disease and progression to colon cancer

Epithelial cell MUC1 is aberrantly expressed on human epithelial adenocarcinomas where it functions as a regulator of immune responses and an oncogene. Normally expressed at low levels in healthy colonic epithelium, MUC1 was reported to be overexpressed in human inflammatory bowel disease (IBD) and thus may be expected to play an important role in regulating chronic inflammation and its progression to colitis-associated colon cancer. Studies in the immunobiology and pathology of IBD and colitis-associated colon cancer have been done in various mouse models but none could properly address the role of MUC1 due to low homology between the mouse and the human molecule. We report that IL-10(-/-) mice, a widely accepted mouse model of IBD, crossed to human MUC1-transgenic mice, develop MUC1(+) IBD characterized by an earlier age of onset, higher inflammation scores, and a much higher incidence and number of colon cancers compared with IL-10(-/-) mice.