Overcoming Xenoantigen Immunity to Enable Cellular Tracking and Gene Regulation with Immune-competent "NoGlow" Mice

The ability to temporally regulate gene expression and track labeled cells makes animal models powerful biomedical tools. However, sudden expression of xenobiotic genes [e.g., GFP, luciferase (Luc), or rtTA3] can trigger inadvertent immunity that suppresses foreign protein expression or results in complete rejection of transplanted cells. Germline exposure to foreign antigens somewhat addresses these challenges; however, native fluorescence and bioluminescence abrogates the utility of reporter proteins and highly spatiotemporally restricted expression can lead to suboptimal xenoantigen tolerance. To overcome these unwanted immune responses and enable reliable cell tracking/gene regulation, we developed a novel mouse model that selectively expresses antigen-intact but nonfunctional forms of GFP and Luc, as well as rtTA3, after CRE-mediated recombination. Using tissue-specific CREs, we observed model and sex-based differences in immune tolerance to the encoded xenoantigens, illustrating the obstacles of tolerizing animals to foreign genes and validating the utility of these "NoGlow" mice to dissect mechanisms of central and peripheral tolerance. Critically, tissue unrestricted NoGlow mice possess no detectable background fluorescence or luminescence and exhibit limited adaptive immunity against encoded transgenic xenoantigens after vaccination. Moreover, we demonstrate that NoGlow mice allow tracking and tetracycline-inducible gene regulation of triple-transgenic cells expressing GFP/Luc/rtTA3, in contrast to transgene-negative immune-competent mice that eliminate these cells or prohibit metastatic seeding. Notably, this model enables de novo metastasis from orthotopically implanted, triple-transgenic tumor cells, despite high xenoantigen expression. Altogether, the NoGlow model provides a critical resource for in vivo studies across disciplines, including oncology, developmental biology, infectious disease, autoimmunity, and transplantation.

SIGNIFICANCE

Multitolerant NoGlow mice enable tracking and gene manipulation of transplanted tumor cells without immune-mediated rejection, thus providing a platform to investigate novel mechanisms of adaptive immunity related to metastasis, immunotherapy, and tolerance.

Abstract 696: Sensitizing breast cancers to immune checkpoint inhibitors through CD27 agonism and vaccination against tumor-associated antigen

Project objective: Despite the recent revolution in immune checkpoint inhibitors (ICIs), only modest improvement in overall survival and likely caused by not enough potent cellular immunity among BC patients. Our lab has been focus on inducing cellular immunity against HER2+ BC through vaccination against the tumor-associated antigen HER2. Approximately 20 years ago, we performed an experimental pilot study by administrating HER2 peptide and recombinant protein pulsed dendritic cells (DC vaccine) to six patients with refractory HER2+ advanced or metastatic (stage II (≥ 6 +LN), III, or stage IV) BC. We followed the patients on 2019 found that all of the six patients were still alive, 18 years after vaccination. Their blood sample were analyzed with cytometry by time-of-flight (CyTOF) and found there is a significantly increased presence of CD27 expressing memory T cells in response to HER2 peptide stimulation. Recent report on the SARS-CoV2 mRNA vaccine also suggested that CD27 expressing memory T cells plays a critical role in long-lasting cellular immunity against SARS-CoV2 infection. Therefore, we hypothesized that CD27 plays a critical role in cellular immunity against BC, and the stimulation of CD27 expressing T cells with mAb targeting CD27 significantly increase the cellular immunity triggered by vaccination against tumor-associated antigen.

Results: We recapitulate the rise of CD27+ antigen specific T cells among the vaccinated patients using a transgenic mouse model expressing human CD27. When combined the adenoviral-vector based HER2 (Ad-HER2) vaccination with a single dose of human aCD27 antibody (Varlilumab), we found there is a robust increase in the HER2 specific T cells compared to vaccination alone, especially CD27+CD44+ memory CD4 T cells, even after 120 days post vaccination. Using an ICI-insensitive syngeneic HER2+ BC models, we found 50% of mice in the combination group of aCD27 antibody plus Ad-HER2 showed total tumor regression by the end of study. When combined with anti-PD1 antibody, the combination of AdHER2 and Varlilumab leads to total tumor regression in 90% of tumor bearing mice with syngeneic HER2+ BC, indicating that the vaccination against tumor associated antigen HER2 plus anti-CD27 antibody sensitized ICI-insensitive HER2+ BC toward ICI.

Conclusions: Our data demonstrates that the administration of anti-CD27 antibody significantly increase the long term presence of CD27+ antigen specific memory T cells after vaccination against tumor associated antigen HER2. As consequence, combination of anti-CD27 with HER2 sensitized the immune unresponsive breast cancer toward anti-PD1 antibody. Our study suggests that the vaccination against tumor-associated antigen with mAb targeting CD27 leads to the robust cellular immunity, which is required for successful ICIs against breast cancer.

Citation Format: Bin-Jin Hwang, Erika Crosby, Timothy Trotter, Li-Chung Tsao, Tao Wang, Xiao Yang, Herbert Kim Lyerly, Zachary Hartman. Sensitizing breast cancers to immune checkpoint inhibitors through CD27 agonism and vaccination against tumor-associated antigen [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 696.

A Non-Invasive Deep Photoablation Technique to Inhibit DCIS Progression and Induce Antitumor Immunity

Ductal carcinoma in situ (DCIS) of the breast is often managed by lumpectomy and radiation or mastectomy, despite its indolent features. Effective non-invasive treatment strategies could reduce the morbidity of DCIS treatment. We have exploited the high heat shock protein 90 (HSP90) activity in premalignant and malignant breast disease to non-invasively detect and selectively ablate tumors using photodynamic therapy (PDT). PDT with the HSP90-targeting photosensitizer, HS201, can not only ablate invasive breast cancers (BCs) while sparing non-tumor tissue, but also induce antitumor immunity. We hypothesized that HS201-PDT would both non-invasively ablate DCIS and prevent progression to invasive BC. We tested in vitro selective uptake and photosensitivity of HS201 in DCIS cell lines compared to the non-selective parental verteporfin, and assessed in vivo antitumor efficacy in mammary fat pad and intraductal implantation models. Selective uptake of HS201 enabled treatment of intraductal lesions while minimizing toxicity to non-tumor tissue. The in vivo activity of HS201-PDT was also tested in female MMTV-neu mice prior to the development of spontaneous invasive BC. Mice aged 5 months were administered HS201, and their mammary glands were exposed to laser light. HS201-PDT delayed the emergence of invasive BC, significantly prolonged disease-free survival (DFS) (p = 0.0328) and tended to improve overall survival compared to the no-treatment control (p = 0.0872). Systemic administration of anti-PD-L1 was combined with HS201-PDT and was tested in a more aggressive spontaneous tumor model, HER2delta16 transgenic mice. A single PDT dose combined with anti-PD-L1 improved DFS compared to the no-treatment control, which was significantly improved with repetitive HS201-PDT given with anti-PD-L1 (p = 0.0319). In conclusion, a non-invasive, skin- and tissue-sparing PDT strategy in combination with anti-PD-L1 antibodies effectively prevented malignant progression of DCIS to invasive BC. This non-invasive treatment strategy of DCIS may be safe and effective, while providing an option to reduce the morbidity of current conventional treatment for patients with DCIS. Clinical testing of HS201 is currently underway.

Combination of a novel heat shock protein 90-targeted photodynamic therapy with PD-1/PD-L1 blockade induces potent systemic antitumor efficacy and abscopal effect against breast cancers

BACKGROUND

We previously demonstrated potent antitumor activity against human breast cancer xenografts using photodynamic therapy (PDT) targeting a novel tumor-specific photosensitizer (HS201), which binds heat shock protein 90 (HS201-PDT). However, induction of systemic antitumor immunity by HS201-PDT alone or by the combination strategy with immune checkpoint blockade has yet to be determined.

METHODS

Using unilateral and bilateral implantation models of syngeneic breast tumors (E0771, MM3MG-HER2, and JC-HER3) in mice, we assessed whether HS201-PDT could induce local and systemic antitumor immunity. In an attempt to achieve a stronger abscopal effect for distant tumors, the combination strategy with anti-PD-L1 antibody was tested. Tumor-infiltrating leukocytes were analyzed by single cell RNA-sequencing and receptor-ligand interactome analysis to characterize in more detailed the mechanisms of action of the treatment and key signaling pathways involved.

RESULTS

HS201-PDT demonstrated greater tumor control and survival in immune competent mice than in immunocompromised mice, suggesting the role of induced antitumor immunity; however, survival was modest and an abscopal effect on distant implanted tumor was weak. A combination of HS201-PDT with anti-PD-L1 antibody demonstrated the greatest antigen-specific immune response, tumor growth suppression, prolonged mouse survival time and abscopal effect. The most significant increase of intratumoral, activated CD8+T cells and decrease of exhausted CD8+T cells occurred following combination treatment compared with HS201-PDT monotherapy. Receptor-ligand interactome analysis showed marked enhancement of several pathways, such as CXCL, GALECTIN, GITRL, PECAM1 and NOTCH, associated with CD8+T cell activation in the combination group. Notably, the expression of the CXCR3 gene signature was the highest in the combination group, possibly explaining the enhanced tumor infiltration by T cells.

CONCLUSIONS

The increased antitumor activity and upregulated CXCR3 gene signature induced by the combination of anti-PD-L1 antibody with HS201-PDT warrants the clinical testing of HS201-PDT combined with PD-1/PD-L1 blockade in patients with breast cancer, and the use of the CXCR3 gene signature as a biomarker.

Action for Increasing Diversity, Market Access, and Capacity in Oncology Registration Trials—Is Africa the Answer? Report From a Satellite Session of the Accelerating Anti-Cancer Agent Development and Validation Workshop

Patients of African ancestry are not well-represented in cancer clinical trials despite bearing a disproportionate share of mortality both in United States and Africa. We describe key stakeholder perspectives and priorities related to bringing early-stage cancer clinical trials to Africa and outline essential action steps. Increasing Diversity, Market Access, and Capacity in Oncology Registration Trials—Is Africa the Answer? satellite session was organized at 2021 Accelerating Anti-Cancer Agent Development and Validation Workshop. Panelists included representatives of African Organization for Research and Training in Cancer, Uganda Cancer Institute, Uganda Women's Cancer Support Organization, BIO Ventures for Global Health, Bill & Melinda Gates Foundation, the US Food and Drug Administration, Nigeria's National Agency for Food and Drug Administration and Control, Bayer, and Genentech, with moderators from ASCO and American Cancer Society. Key discussion themes and resulting action steps were agreed upon by all participants. Panelists agreed that increasing diversity in cancer clinical trials by including African patients is key to ensuring novel drugs are safe and effective across populations. They underscored the importance of equity in clinical trial access for patients in Africa. Panelists discussed their values related to access and barriers to opening clinical trials in Africa and described innovative solutions from their work aimed at overcoming these obstacles. Multisectoral collaboration efforts that allow leveraging of limited resources and result in sustainable capacity building and mutually beneficial long-term partnerships were discussed as key to outlined action steps. The panel discussion resulted in valuable insights about key stakeholder values and priorities related to bringing early-stage clinical trials to Africa, as well as specific actions for each stakeholder group.

Abstract 3531: Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression

Background: The majority of colorectal carcinomas (CRCs) are insensitive to anti-PD-1/PD-L1 immune checkpoint inhibitor (ICI) antibodies. While there are many causes for ICI insensitivity, recent studies suggest that the suppression of innate immunity through a loss of innate immune adaptor expression could be a root cause of this insensitivity and an important factor in the evolution of tumor immunosuppression.

Methods: We interrogated mitochondrial antiviral signaling gene (MAVS) expression through bioinformatics analyses of multiple datasets to validate its suppression in clinical samples. We then engineered MAVS expressing tumor cells and tested its ability to elicit innate and adaptive anti-tumor immunity using both in vitro and in vivo approaches, which we then confirmed using MAVS expressing viral vectors. Finally, we observed that MAVS stimulated PD-L1expression in different types of tumor cells and then assessed the combination of PD-L1 ICI antibodies with MAVS tumor expression in vivo.

Results: MAVS was significantly downregulated in CRCs, but its re-expression could stimulate broad cellular interferon-related responses, in both murine and patient-derived CRCs. In vivo, local MAVS expression elicited significant anti-tumor responses in both immune-sensitive and insensitive CRC models, through the stimulation of an interferon responsive axis that elicited tumor antigen-specific adaptive immunity. Critically, we found that tumor-intrinsic MAVS expression triggered systemic adaptive immune responses that enabled abscopal CD8+ T cell cytotoxicity against distant CRCs. As MAVS also induced PD-L1 expression, we further found synergistic anti-tumor responses in combination with anti-PD-L1 ICIs.

Conclusion: These data demonstrate that intratumoral MAVS expression results in local and systemic tumor antigen-specific T cell responses, which could be combined with PD-L1 ICI to permit effective anti-tumor immunotherapy in ICI resistant cancers. We are further exploring to overcome the ICI insensitivity of other types of solid tumor, with MAVS-delivery strategies other than viral vectors.

Citation Format: Bin-Jin Hwang, Li-Chung Tsao, Chaitanya Acharya, Timothy Trotter, Pankaj Agarwal, Tao Wang, Junping Wei, Xiao-Yi Yang, Gang-jun Lei, Takuya Osada, Herbert Kim Lyerly, Michael A. Morse, Zachary Hartman. Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3531.

Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression

Background

The majority of colorectal carcinomas (CRCs) are insensitive to programmed death protein-1/programmed death-ligand 1 (anti-PD-1/PD-L1) immune checkpoint inhibitor (ICI) antibodies. While there are many causes for ICI insensitivity, recent studies suggest that suppression of innate immune gene expression in tumor cells could be a root cause of this insensitivity and an important factor in the evolution of tumor immunosuppression.

Methods

We first assessed the reduction of mitochondrial antiviral signaling gene (MAVS) and related RIG-I pathway gene expression in several patient RNA expression datasets. We then engineered MAVS expressing tumor cells and tested their ability to elicit innate and adaptive anti-tumor immunity using both in vitro and in vivo approaches, which we then confirmed using MAVS expressing viral vectors. Finally, we observed that MAVS stimulated PD-L1 expression in multiple cell types and then assessed the combination of PD-L1 ICI antibodies with MAVS tumor expression in vivo.

Results

MAVS was significantly downregulated in CRCs, but its re-expression could stimulate broad cellular interferon-related responses, in both murine and patient-derived CRCs. In vivo, local MAVS expression elicited significant anti-tumor responses in both immune-sensitive and insensitive CRC models, through the stimulation of an interferon responsive axis that provoked tumor antigen-specific adaptive immunity. Critically, we found that tumor-intrinsic MAVS expression triggered systemic adaptive immune responses that enabled abscopal CD8 +T cell cytotoxicity against distant CRCs. As MAVS also induced PD-L1 expression, we further found synergistic anti-tumor responses in combination with anti-PD-L1 ICIs.

Conclusion

These data demonstrate that intratumoral MAVS expression results in local and systemic tumor antigen-specific T cell responses, which could be combined with PD-L1 ICI to permit effective anti-tumor immunotherapy in ICI resistant cancers.

Trastuzumab/Pertuzumab combination therapy stimulates anti-tumor responses through complement-dependent cytotoxicity and phagocytosis

Standard-of-care treatment for advanced HER2+ breast cancers (BC) is comprised of two HER2-specific monoclonal antibodies (mAb), Trastuzumab (T) and Pertuzumab (P) with chemotherapy. While this combination (T+P) is highly effective, its synergistic mechanism of action (MOA) is not completely known. Initial studies had demonstrated that Pertuzumab suppressed HER2 hetero-dimerization as the potential therapeutic MOA, thus the improved outcome associated with the T+P combination MOA compared to Trastuzumab alone has been widely reported as being due to Pertuzumab-mediated suppression of HER2 signaling in combination with Trastuzumab-mediated induction of anti-tumor immunity. Unraveling this MOA may be critical to extend this combination strategy to other antigens or other cancers, as well as improving this current treatment modality. Using novel murine and human versions of Pertuzumab, we found it induced both Antibody-Dependent-Cellular-Phagocytosis (ADCP) by tumor-associated macrophages and suppression of HER2 oncogenic signaling. Most significantly, we identified that only T+P combination therapy, but not when either antibody used in isolation, allows for the activation of the classical complement pathway, resulting in both direct complement-dependent cytotoxicity (CDC) as well as complement-dependent cellular phagocytosis (CDCP) of HER2+ BC cells. Notably, we show that tumor expression of C1q was positively associated with survival outcome in HER2+ BC patients, whereas expression of complement regulators CD55 and CD59 were inversely correlated, suggesting the importance of complement activity in clinical outcomes. Accordingly, inhibition of C1 activity in mice abolished the synergistic therapeutic activity of T+P therapy, whereas knockdown of CD55 and CD59 expression enhanced T+P efficacy. In summary, our study identifies classical complement activation as a significant anti-tumor MOA for T+P therapy that may be functionally enhanced to augment therapeutic efficacy in the clinic.

Combination of ultrasound-based mechanical disruption of tumor with immune checkpoint blockade modifies tumor microenvironment and augments systemic antitumor immunity

Background

Despite multimodal adjuvant management with radiotherapy, chemotherapy and hormonal therapies, most surgically resected primary breast cancers relapse or metastasize. A potential solution to late and distant recurrence is to augment systemic antitumor immunity, in part by appropriately presenting tumor antigens, but also by modulating the immunosuppressive tumor microenvironment (TME). We previously validated this concept in models of murine carcinoma treated with a novel predominately microcavitating version of high-intensity focused ultrasound (HIFU), mechanical high-intensity focused ultrasound (M-HIFU). Here we elucidated the mechanisms of enhanced antitumor immunity by M-HIFU over conventional thermal high-intensity focused ultrasound (T-HIFU) and investigated the potential of the combinatorial strategy with an immune checkpoint inhibitor, anti-PD-L1 antibody.

Methods

The antitumor efficacy of treatments was investigated in syngeneic murine breast cancer models using triple-negative (E0771) or human ErbB-2 (HER2) expressing (MM3MG-HER2) tumors in C57BL/6 or BALB/c mice, respectively. Induction of systemic antitumor immunity by the treatments was tested using bilateral tumor implantation models. Flow cytometry, immunohistochemistry, and single-cell RNA sequencing were performed to elucidate detailed effects of HIFU treatments or combination treatment on TME, including the activation status of CD8 T cells and polarization of tumor-associated macrophages (TAMs).

Results

More potent systemic antitumor immunity and tumor growth suppression were induced by M-HIFU compared with T-HIFU. Molecular characterization of the TME after M-HIFU by single-cell RNA sequencing demonstrated repolarization of TAM to the immunostimulatory M1 subtype compared with TME post-T-HIFU. Concurrent anti-PD-L1 antibody administration or depletion of CD4⁺ T cells containing a population of regulatory T cells markedly increased T cell-mediated antitumor immunity and tumor growth suppression at distant, untreated tumor sites in M-HIFU treated mice compared with M-HIFU monotherapy. CD8 T and natural killer cells played major roles as effector cells in the combination treatment.

Conclusions

Physical disruption of the TME by M-HIFU repolarizes TAM, enhances T-cell infiltration, and, when combined with anti-PD-L1 antibody, mediates superior systemic antitumor immune responses and distant tumor growth suppression. These findings suggest M-HIFU combined with anti-PD-L1 may be useful in reducing late recurrence or metastasis when applied to primary tumors.

Blood microbiota diversity determines response of advanced colorectal cancer to chemotherapy combined with adoptive T cell immunotherapy

Human microbiota influence the response of malignancies to treatment with immune checkpoint blockade; however, their impact on other forms of immunotherapy is poorly understood. This study explored the effect of blood microbiota on clinical efficacy, represented by progression-free survival (PFS) and overall survival (OS), of combined chemotherapy and adoptive cellular therapy (ACT) in advanced colon cancer patients. Plasma was collected from colorectal cancer patients (CRC) treated with either chemotherapy alone (oxaliplatin and capecitabine) (XELOX CT alone group, n = 19), or ACT with a mixed dendritic cell/cytokine-induced killer cell product (DC-CIK) + XELOX (ICT group, n = 20). Circulating microbiota analysis was performed by PCR amplification and next-generation sequencing of variable regions V3~V4 of bacterial 16S rRNA genes. The association of the blood microbial diversity with clinical response to the therapy as measured by RECIST1.1 and OS was evaluated. The baseline Chao index of blood microbial diversity predicted prolonged PFS and OS of DC/CIK immunotherapy. More diverse blood microbiota that included Bifidobacterium, Lactobacillus, and Enterococcus were identified among responders to DC/CIK compared with non-responders. The plasma bacterial DNA copy number is inversely correlated with the CD3-/CD16+/CD56+ NK cells in circulation and decreased following DC-CIK; however, the Chao index of plasma microbiota significantly increased after administration of the DC-CIK product and this subsequent change was correlated with the number of CD3-/CD16+/CD56+ and CD8+/CD28+ cells infused. The diversity of the blood microbiome is a promising predictive marker for clinical responses to chemotherapy combined with DC-CIK. Cellular immunotherapy can affect the plasma microbiota's diversity in a manner favorable to clinical responses.

Changes in Peripheral Blood Regulatory T Cells and IL-6 and IL-10 Levels Predict Response of Pediatric Medulloblastoma and Germ Cell Tumors With Residual or Disseminated Disease to Craniospinal Irradiation

PURPOSE

Radiation therapy (RT) modulates immune cells and cytokines, resulting in both clinically beneficial and detrimental effects. The changes in peripheral blood T lymphocyte subsets and cytokines during RT for pediatric brain tumors and the association of these changes with therapeutic outcomes have not been well described.

METHODS AND MATERIALS

The study population consisted of children (n = 83, aged 3~18) with primary brain tumors (medulloblastoma, glioma, germ cell tumors (GCT), and central nervous system embryonal tumor-not otherwise specified), with or without residual or disseminated (R/D) diseases who were starting standard postoperative focal or craniospinal irradiation (CSI). Peripheral blood T lymphocyte subsets collected before and 4 weeks after RT were enumerated by flow cytometry. Plasma levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor-α, interferon-γ, and IL-17A were measured by cytometric bead array.

RESULTS

Patients with R/D lesions receiving CSI (n = 32) had a post-RT increase in the frequency of CD3+T and CD8+T cells, a decrease in CD4+T cells, and an increase in regulatory T cells (Tregs) and CD8+CD28- suppressor cells, which was more predominantly seen in these patients than in other groups. In the CSI group with such R/D lesions, consisting of patients with medulloblastoma and germ cell tumors, 19 experienced a complete response (CR) and 13 experienced a partial response (PR) on imaging at 4 weeks after RT. The post/pre-RT ratio of Tregs (P = .0493), IL-6 (P = .0111), and IL-10 (P = .0070) was lower in the CR group than in the PR group. Multivariate analysis revealed that the post/pre-RT ratios of Treg, IL-6, and IL-10 were independent predictors of CR (P < .0001, P = .018, P < .0001, respectively). The areas under the receiver operating curves and confidence intervals were 0.7652 (0.5831-0.8964), 0.7794 (0.5980-0.9067), and 0.7085 (0.5223-0.8552) for IL-6, IL-10, and Treg, respectively. The sensitivities of IL-6, IL-10, and Treg to predict radiotherapeutic responses were 100%, 92.3%, and 61.5%, and specificity was 52.6%, 57.9%, and 84.2%, respectively.

CONCLUSIONS

CSI treatment to those with R/D lesions predominantly exerted an effect on antitumor immune response compared with both R/D lesion-free but exposed to focal or CSI RT and with R/D lesions and exposed to focal RT. Such CSI with R/D lesions group experiencing CR is more likely to have a decrease in immunoinhibitory molecules and cells than patients who only achieve PR. Measuring peripheral blood Treg, IL-6, and IL-10 levels could be valuable for predicting radiotherapeutic responses of pediatric brain tumors with R/D lesions to CSI for medulloblastoma and intracranial germ cell tumors.

Serial assessment of circulating T lymphocyte phenotype and receptor repertoire during treatment of non-muscle invasive bladder cancer with adoptive T cell immunotherapy

Recurrence and progression of non-muscle-invasive bladder cancer (NMIBC), frequent despite the availability of multiple treatment modalities, may be partly explained by the presence of immunosuppressive cell populations. We hypothesized that progression of disease could be prevented by the administration of an activated T cell immunotherapy (ACT) at time points when immunosuppressive populations increased in peripheral blood. In an N-of-1 study, a patient with multiple primary bladder high grade urothelial carcinomas, previously treated with standard local resection and chemotherapy but with evidence of progression, received ACT consisting of dendritic cells mixed with cytokine induced killer cells (DC/CIK), intravenously 18 times over a 6 year period at indicated time of observed increases in peripheral blood immunosuppressive CD8⁺/CD28^- cells. Peripheral blood was analyzed for T cell phenotype by flow cytometry, T cell receptor (TCR) repertoire, and circulating tumor DNA (ctDNA) by next generation sequencing (NGS) at the time of each infusion. Cystoscopy and pelvic CT scans were performed at routine intervals to assess clinical status of disease. There has been no recurrence or metastasis of urothelial carcinoma. Peripheral blood cytotoxic T cells and unique TCR clones increased and suppressive T cell populations decreased after DC/CIK infusions evidenced by the two more proof-of concept cases. ctDNA analysis detected mutations in six genes (ARID1B, MYCN, CDH23, SETD2, NOTCH4 and FAT1) which appeared at different times, but all of them disappeared after the DC-CIK infusions. These data suggest that DC/CIK infusions may be associated with beneficial changes in T cell phenotype, TCR repertoire, decreases in circulating tumor DNA and sustained recurrence-free survival.

Abstract PS17-22: Intratumoral delivery of tavokinogene telseplasmid (plasmid IL-12) and electroporation induces an immune signature that predicts successful combination in patients

Interleukin-12 (IL-12) is a pro-inflammatory cytokine involved in the generation of an inflammatory tumor microenvironment and is critical in eliciting a productive anti-tumor immune response. It has been investigated as an anti-cancer therapeutic using various delivery routes, but intratumoral injection of plasmid IL-12 (tavokinogene telseplasmid; TAVO) followed by electroporation is a gene therapy approach that results in more sustained production of IL-12 locally with minimal systemic immune-related toxicity. Here we show that TAVO not only provides protection in the treated triple-negative breast cancer (TNBC) lesion, but also induces a systemic, abscopal effect. Single cell RNAsequencing (scRNAseq) of infiltrating immune cells shows a significant increase in both CD4 and CD8 T cells as well as dendritic cells within the treated lesions, while simultaneously decreasing a granulocytic myeloid derived suppressor population. scRNAseq allows for a detailed look into not only the overall pathway enrichment caused by TAVO treatment, but also the specific receptor-ligand interactions occurring between cell types. A combination of these analyses revealed an enrichment in the IFN-gamma induced PDL1 pathway by TAVO, typified by an increase in the interaction between PDL1 on dendritic cells and PD1 on CD8 T cells. Further, dramatic enrichment of the CXCL9/10/11/CXCR3 axis was observed, consistent with previous studies in melanoma. Analysis of paired TCR alpha and beta chains on T cells additionally demonstrated a dramatic shift in tumor infiltrating T cell (TIL) clonality and frequency. In sum, these preclinical studies identify a signature of increased antigen presentation, T cell infiltration and expansion, and a decrease in the number of granulocytes but also a particular enhancement of the PDL1 immunosuppressive pathway following TAVO treatment. Using this signature, we focus on an in-depth analysis of 2 patients from a single arm, prospective clinical trial of TAVO monotherapy (OMS-I140) in pre-treated advanced TNBC that went on to receive anti-PD-1 as their immediate next therapy with clinical anti-tumor response. Together these data support the combination of TAVO with PD1/PDL1 inhibitors while also identifying other key pathways that may enhance responsiveness in TNBC patients for whom treatment options remain limited.

Citation Format: Erika J Crosby, Hiroshi Nagata, Melinda L Telli, Chaitanya R Acharya, Irene Wapnir, Kaitlin Zablotsky, Erica Browning, Reneta Hermiz, Lauren Svenson, Donna Bannavong, Kellie Malloy, David A Canton, Chris G Twitty, Takuya Osada, Herbert Kim Lyerly. Intratumoral delivery of tavokinogene telseplasmid (plasmid IL-12) and electroporation induces an immune signature that predicts successful combination in patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-22.

Infiltration of metastatic lymph nodes with PD-1+ T cells is associated with improved disease-free and overall survival in resected N+ NSCLC

Tumor metastases to regional lymph nodes are associated with worse outcome for patients with resected non-small cell lung cancer (NSCLC), but there is a wide variation in survival. We hypothesized that infiltration of tumor-involved lymph nodes with activated effector T cells would impact subsequent outcome. A total of 54 lymph nodes (27 N⁺ and 15 N^- collected from 12 patients with Stage IIB (T₂N₁M₀) and 12 N^- lymph nodes collected from 10 patients with Stage IIA (T₂N₀M₀) who underwent lymphadenectomy during surgical management of their NSCLC) were analyzed for effector T cells expressing activation markers PD-1 and TIM-3 using the Opal-multiple immunofluorescence assay. The frequency of CD3⁺CD8⁺ (P=0.0001), CD3⁺CD8⁺TIM-3⁺ (P<0.0001), and CD3⁺CD8⁺TIM-3⁺Ki-67⁺ (P<0.0001) T cells was greater in lymph nodes of IIA patients compared with IIB patients; however the frequency of CD3⁺CD8⁺PD-1⁺ (P=0.0086), CD3⁺CD8⁺TIM-3⁺ (P=0.0129), CD3⁺CD8⁺PD-1⁺Ki-67⁺ (P<0.0001) and CD3⁺CD8⁺TIM-3⁺Ki-67⁺ (P=0.0001) T cells was greater among the tumor involved (N⁺) nodes of N1 patients compared with the tumor-uninvolved (N^-) nodes. The frequency of intranodal CD3⁺CD8⁺, CD3⁺CD8⁺PD-1⁺ and CD3⁺CD8⁺PD-1⁺Ki-67⁺ T cells in N⁺ nodes was associated with prolonged progression-free (PFS) and overall survival (OS). These data suggest that CD3⁺CD8⁺TIM-3⁺ T cells may suppress tumor spread to regional lymph nodes but once tumor cells metastasize to lymph nodes, CD3⁺/CD8⁺/PD-1⁺/Ki67⁺ T cells localizing to N⁺ nodes may prevent further tumor spread, resulting in prolonged survival.

Long-term survival of patients with stage III colon cancer treated with VRP-CEA(6D), an alphavirus vector that increases the CD8+ effector memory T cell to Treg ratio

BACKGROUND

There remains a significant need to eliminate the risk of recurrence of resected cancers. Cancer vaccines are well tolerated and activate tumor-specific immune effectors and lead to long-term survival in some patients. We hypothesized that vaccination with alphaviral replicon particles encoding tumor associated antigens would generate clinically significant antitumor immunity to enable prolonged overall survival (OS) in patients with both metastatic and resected cancer.

METHODS

OS was monitored for patients with stage IV cancer treated in a phase I study of virus-like replicon particle (VRP)-carcinoembryonic antigen (CEA), an alphaviral replicon particle encoding a modified CEA. An expansion cohort of patients (n=12) with resected stage III colorectal cancer who had completed their standard postoperative adjuvant chemotherapy was administered VRP-CEA every 3 weeks for a total of 4 immunizations. OS and relapse-free survival (RFS) were determined, as well as preimmunization and postimmunization cellular and humoral immunity.

RESULTS

Among the patients with stage IV cancer, median follow-up was 10.9 years and 5-year survival was 17%, (95% CI 6% to 33%). Among the patients with stage III cancer, the 5-year RFS was 75%, (95%CI 40% to 91%); no deaths were observed. At a median follow-up of 5.8 years (range: 3.9-7.0 years) all patients were still alive. All patients demonstrated CEA-specific humoral immunity. Patients with stage III cancer had an increase in CD8 +T_EM (in 10/12) and decrease in FOXP3 +Tregs (in 10/12) following vaccination. Further, CEA-specific, IFNγ-producing CD8+granzyme B+T_CM cells were increased.

CONCLUSIONS

VRP-CEA induces antigen-specific effector T cells while decreasing Tregs, suggesting favorable immune modulation. Long-term survivors were identified in both cohorts, suggesting the OS may be prolonged.

Novel Therapeutic Interventions Early in the Disease Trajectory: Drug Development Beyond the Refractory Setting

The 2019 Accelerating Anticancer Agent Development Workshop assembled a panel of experts for an in-depth discussion session to present "novel therapeutic interventions early in the disease trajectory." The panel reviewed the limitations of evaluating investigational cancer therapeutics solely in advanced metastatic and relapsed/refractory disease settings, and recommended strategies for drug evaluation earlier in the disease course, including in the first line in combination with standard chemotherapy, and in the maintenance and neoadjuvant disease settings. Advantages of earlier drug evaluation were discussed, including expanding the population of evaluable patients, earlier response assessment via surrogate endpoints, earlier clinical benefit in the disease course, tailoring of therapies based on response, and furthering our understanding of biomarker-driven therapies.

Clinical efficacy of intra-cavitary infusions of autologous dendritic cell/cytokine-induced killer cell products for the treatment of refractory malignant pleural effusions and ascites

To explore the safety and efficacy of intra-cavitary infusions of autologous mixed dendritic cell (DC)-cytokine-induced killer (CIK) cell products in advanced cancer patients with malignant pleural effusions or ascites. DC-CIKs were expanded ex vivo (mean yield of 1.36×10⁹ cells (range, 0.74~4.98×10⁹)) from peripheral blood mononuclear cells obtained by repeated venipuncture or apheresis. Patients received at least 1 cycle of 3 infusions of the DC-CIKs administered by indwelling catheter into the pleural or peritoneal cavity every other day. The volume of malignant effusions was assessed radiologically. Peripheral blood lymphocyte populations were enumerated by flow cytometry. Quality of life (QoL) during the DC-CIK infusions was assessed by the EORTC QLQ-30 instrument. ctDNA sequencing was performed to analyze gene clonal load and molecular tumor burden during the infusion treatment. Thirty-seven patients with breast, lung and other malignancies were enrolled. The results showed that intra-cavitary DC-CIK infusions (16 intrapleural and 21 intraperitoneal) were well-tolerated with no grade 3/4 adverse events. There was one complete response with effusion disappearance (CR) (3%), 13 partial responses (PR) (35%), 12 with stable disease (SD) (32%) and 11 with progressive disease (PD) (30%), resulting in a clinical effusion control rate (CCR) of 70% (26/37). The total number of infused CIKs and the CD3+/CD8+ and CD8+/CD28+ T cell frequencies within the CIKs were associated with effusion control (P=0.013). Moreover, increased peripheral blood CD3+/CD8+ (P=0.035) and decreased CD4+/CD25+ T cell frequencies (P=0.041) following the DC-CIK infusions were associated with malignant effusion and ascites control. Reductions in ctDNA correlated with clinical benefit. In conclusion, intra-cavitary autologous cellular immunotherapy is an alternative method to effectively control malignant pleural effusions and ascites. The overall effusion control rate was associated with higher peripheral blood effector T cell frequencies.

HER2-LAMP vaccines effectively traffic to endolysosomal compartments and generate enhanced polyfunctional T cell responses that induce complete tumor regression

BACKGROUND

The advent of immune checkpoint blockade antibodies has demonstrated that effective mobilization of T cell responses can cause tumor regression of metastatic cancers, although these responses are heterogeneous and restricted to certain histologic types of cancer. To enhance these responses, there has been renewed emphasis in developing effective cancer-specific vaccines to stimulate and direct T cell immunity to important oncologic targets, such as the oncogene human epidermal growth factor receptor 2 (HER2), expressed in ~20% of breast cancers (BCs).

METHODS

In our study, we explored the use of alternative antigen trafficking through use of a lysosome-associated membrane protein 1 (LAMP) domain to enhance vaccine efficacy against HER2 and other model antigens in both in vitro and in vivo studies.

RESULTS

We found that inclusion of this domain in plasmid vaccines effectively trafficked antigens to endolysosomal compartments, resulting in enhanced major histocompatibility complex (MHC) class I and II presentation. Additionally, this augmented the expansion/activation of antigen-specific CD4+ and CD8+ T cells and also led to elevated levels of antigen-specific polyfunctional CD8+ T cells. Significantly, vaccination with HER2-LAMP produced tumor regression in ~30% of vaccinated mice with established tumors in an endogenous model of metastatic HER2+ BC, compared with 0% of HER2-WT vaccinated mice. This therapeutic benefit is associated with enhanced tumor infiltration of activated CD4+ and CD8+ T cells.

CONCLUSIONS

These data demonstrate the potential of using LAMP-based endolysosomal trafficking as a means to augment the generation of polyfunctional, antigen-specific T cells in order to improve antitumor therapeutic responses using cancer antigen vaccines.

An age-independent gene signature for monitoring acute rejection in kidney transplantation

Acute rejection (AR) remains a significant problem that negatively impacts long-term renal allograft survival. Numerous therapies are used to prevent AR that differ by center and recipient age. This variability confounds diagnostic methods. Methods: To develop an age-independent gene signature for AR effective across a broad array of immunosuppressive regimens, we compiled kidney transplant biopsy (n=1091) and peripheral blood (n=392) gene expression profiles from 12 independent public datasets. After removing genes differentially expressed in pediatric and adult patients, we compared gene expression profiles from biopsy and peripheral blood samples of patients with AR to those who were stable (STA), using Mann-Whitney U Tests with validation in independent testing datasets. We confirmed this signature in pediatric and adult patients (42 AR and 47 STA) from our institutional biorepository. Results: We identified a novel age-independent gene network that identified AR from both kidney and blood samples. We developed a 90-probe set signature targeting 76 genes that differentiated AR from STA and found an 8 gene subset (DIP2C, ENOSF1, FBXO21, KCTD6, PDXDC1, REXO2, HLA-E, and RAB31) that was associated with AR. Conclusion: We used publicly available datasets to create a gene signature of AR that identified AR irrespective of immunosuppression regimen or recipient age. This study highlights a novel model to screen and validate biomarkers across multiple treatment regimens.

Immune correlates of clinical benefit in a phase I study of hyperthermia with adoptive T cell immunotherapy in patients with solid tumors

Purpose: To characterize the T cell receptor (TCR) repertoire, serum cytokine levels, peripheral blood T lymphocyte populations, safety, and clinical efficacy of hyperthermia (HT) combined with autologous adoptive cell therapy (ACT) and either salvage chemotherapy (CT) or anti-PD-1 antibody in patients with previously treated advanced solid tumors.Materials and methods: Thirty-three (33) patients with ovarian, pancreatic, gastric, colorectal, cervical, or endometrial cancer were recruited into the following therapeutic groups: HT + ACT (n = 10), HT + ACT + anti-PD-1 inhibitor (pembrolizumab) (n = 11) and HT + ACT + CT (n = 12). Peripheral blood was collected to analyze TCR repertoire, measurements of cytokines levels and lymphocyte sub-populations before and after treatment.Results: The objective response rate (ORR) was 30% (10/33), including three complete responses (CR) (9.1%) and seven partial responses (PR) (21.2%) and a disease control rate (DCR = CR + PR + SD) of 66.7% (22 of 33). The most common adverse reactions, blistering, subcutaneous fat induration, local heat-related pain, vomiting and sinus tachycardia, were observed in association with HT. IL-2, IL-4, TNF-α, and IFN-γ levels in peripheral blood were significantly increased among the clinical responders (p < 0.05) while IL-6 and IL-10 were elevated among those with progressive disease (p < 0.05). Peripheral blood CD8⁺/CD28⁺ T cells increased (p = 0.002), while the CD4⁺/CD25⁺/CD127⁺Treg cells decreased after therapy (p = 0.012). TCR diversity was substantially increased among the clinical responders.Conclusions: Combining HT with ACT plus either CT or anti-PD-1 antibody was safe, generated clinical responses in previously treated advanced cancers, and promoted TCR repertoire diversity and favorable changes in serum IL-2, IL-4, TNF-α, and IFN-γ levels in clinical responders.

T-Scan: A Genome-wide Method for the Systematic Discovery of T Cell Epitopes

T cell recognition of specific antigens mediates protection from pathogens and controls neoplasias, but can also cause autoimmunity. Our knowledge of T cell antigens and their implications for human health is limited by the technical limitations of T cell profiling technologies. Here, we present T-Scan, a high-throughput platform for identification of antigens productively recognized by T cells. T-Scan uses lentiviral delivery of antigen libraries into cells for endogenous processing and presentation on major histocompatibility complex (MHC) molecules. Target cells functionally recognized by T cells are isolated using a reporter for granzyme B activity, and the antigens mediating recognition are identified by next-generation sequencing. We show T-Scan correctly identifies cognate antigens of T cell receptors (TCRs) from viral and human genome-wide libraries. We apply T-Scan to discover new viral antigens, perform high-resolution mapping of TCR specificity, and characterize the reactivity of a tumor-derived TCR. T-Scan is a powerful approach for studying T cell responses.

IL26, a Noncanonical Mediator of DNA Inflammatory Stimulation, Promotes TNBC Engraftment and Progression in Association with Neutrophils

IL26 is a unique amphipathic member of the IL10 family of cytokines that participates in inflammatory signaling through a canonical receptor pathway. It also directly binds DNA to facilitate cellular transduction and intracellular inflammatory signaling. Although IL26 has almost no described role in cancer, our in vivo screen of inflammatory and cytokine pathway genes revealed IL26 to be one of the most significant inflammatory mediators of mammary engraftment and lung metastatic growth in triple-negative breast cancer (TNBC). Examination of human breast cancers demonstrated elevated IL26 transcripts in TNBC specimens, specifically in tumor cells as well as in Th17 CD4⁺ T cells within clinical TNBC specimens. IL26 did not have an autocrine effect on human TNBC cells, but rather its effect on engraftment and growth in vivo required neutrophils. IL26 enhanced mouse-derived DNA induction of inflammatory cytokines, which were collectively important for mammary and metastatic lung engraftment. To neutralize this effect, we developed a novel IL26 vaccine to stimulate antibody production and suppress IL26-enhanced engraftment in vivo, suggesting that targeting this inflammatory amplifier could be a unique means to control cancer-promoting inflammation in TNBC and other autoimmune diseases. Thus, we identified IL26 as a novel key modulator of TNBC metastasis and a potential therapeutic target in TNBC as well as other diseases reliant upon IL26-mediated inflammatory stimulation. SIGNIFICANCE: These findings identify IL26 as a unique, clinically relevant, inflammatory amplifier that enhances TNBC engraftment and dissemination in association with neutrophils, which has potential as a therapeutic target. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/15/3088/F1.large.jpg.

Abstract B03: Trastuzumab therapy suppresses HER2+ breast tumor growth through inducing ADCP by tumor-associated macrophages and synergizes with CD47 checkpoint blockade

Background: HER2 overexpression and amplification define ~20% of breast cancers (BC) that are currently treated using HER2-specific monoclonal antibodies (mAb), such as trastuzumab. While multiple studies have demonstrated trastuzumab’s efficacy to be largely dependent upon triggering innate and adaptive immune responses, its dominant immune mechanism of therapeutic action (MOA) remains unclear. As trastuzumab’s efficacy is subverted in advanced immunosuppressive cancers, an understanding of its MOA and strategy to boost its immune effect is of critical clinical interest and scientific significance for immunologically enhancing other targeted mAb treatments.

Methods: In this study, we developed a novel fully murine trastuzumab mAb (mTrastuzumab) to determine the MOA for HER2-mAb antitumor efficacy. We utilized these mAbs in multiple models that allowed us to interrogate antibody-dependent cell cytotoxicity and phagocytosis (ADCC and ADCP), as well as complement-dependent cytotoxicity (CDC) in vitro and in vivo. To determine the antitumor efficacy of these HER2 mAbs, we employed orthotopic HER2+ murine cells (transformed by HER2) in immunocompetent, FCGR KO, and immunocompetent settings, as well as utilized a unique transgenic HER2+ BC model driven by an oncogenic isoform of HER2 to best simulate an endogenous mammary tumor immune microenvironment (Turpin et al., 2016).

Results: We found that mTrastuzumab significantly suppressed tumor growth and stimulated the infiltration of tumor-associated macrophages (TAMs), without affecting other immune cell types in the microenvironment. In contrast to other studies, we also found that this antitumor activity did not require adaptive immunity or NK cells, but did require activating Fc-gamma receptor engagement, implicating ADCP as the potential dominant MOA. Consistent with these findings, we further demonstrated that mTrastuzumab activated mFcγR4 and mFcγR3 signaling and elicited significant macrophage-mediated ADCP of HER2+ BC in vitro, but not ADCC or CDC. To test if enhanced ADCP could confer more effective antitumor immunity, we combined mTrastuzumab with blockade of the ADCP checkpoint, CD47 (“don’t eat me signal”), and found that this combination significantly increased mTrastuzumab-mediated ADCP in vitro without altering ADCC. Critically, we also found that this combination significantly enhanced TAM infiltration in vivo, as well as stimulated stronger antitumor efficacy and prolonged survival in highly immunosuppressive tumor microenvironments.

Conclusion: Our study demonstrates the major MOA of clinically relevant HER2 mAbs requires the engagement with TAMs to elicit ADCP of tumor cells, which could be significantly enhanced by CD47 blockade. We conclude CD47 blockade could unleash the full potential of HER2 mAb therapy by abrogating the innate immunosuppressive signals on macrophages to stimulate immunity and enhance antitumor efficacy.

Citation Format: Li-Chung Tsao, Herbert Kim Lyerly, Zachary Hartman. Trastuzumab therapy suppresses HER2+ breast tumor growth through inducing ADCP by tumor-associated macrophages and synergizes with CD47 checkpoint blockade [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B03.

Abstract PR2: Overexpression of MAVS stimulates antitumor immunity and significantly reduces tumor growth of immune-insensitive colorectal cancer in vivo

While the use of immune checkpoint blockade (ICB) has gained significant traction as a viable therapy for cancers, many more cancers remain refractory to these immunotherapies due to their highly immunosuppressive tumor microenvironment (TME). This is perhaps best exemplified in colorectal carcinomas (CRCs) where ~90% of CRCs (non-MSI) are unresponsive to ICBs. Secondary analyses of ICB responders suggest that the presence of T cells and a functional interferon signal transduction pathway within cancer cells is likely required for PDL1 ICB efficacy, as mutations in this pathway confer resistance to PD1/PDL1 therapies. Our studies have indicated that this lack of response may be due to mutations and loss of genes that mediate the innate immune responses in tumor cells, such as MAVS (Mitochondrial Antiviral Signaling Protein), which we found were significantly reduced in colorectal cancer. Thus, we hypothesize that stimulation of the MAVS pathway would elicit strong interferon signaling capable of reversing immunosuppression to allow for successful immune-mediated tumor regression. To circumvent issues associated with single ligand stimulation, we exploited the bow-tie structure of the MAVS through its overexpression as a novel genetic means to elicit ligand free innate immune signaling in the TME. We found that overexpression of MAVS elicited robust stimulation of Type I and II interferon pathways, along with a unique interferon gene signature (through transcriptomic analysis of infected primary cells), in comparison to TLR and STING stimulated counterparts. Using MAVS inducible-expressing colorectal cell lines, we found that MAVS expression stimulated significant antitumor responses in vivo through its stimulation of adaptive tumor-specific immune responses in anti-PDL1-resistant models. Moreover, in 20% (4 out of 20) of MAVS-induced cancers, we observed complete tumor regression as well as an immunologic memory response (in 100% of regressed mice) through tumor rechallenge experiment. Utilizing MAVS expressing viral (adeno and AAV) vectors, we could demonstrate significant induction of interferon responses among different cells in the tumor microenvironment, including tumor cells, fibroblasts, as well as dendritic cells. Intralesional injection of tumors using these vectors elicited profound antitumor responses against primary tumors, as well as an abscopal effect against syngeneic implanted tumors. However, we found that MAVS expression significantly upregulated PDL1 in infected cells, suggesting that MAVS vectors may synergize with PDL1 ICB. In conclusion, our data demonstrate the importance of innate immunity activation by MAVS pathway in generating antitumor effects and immune “hot spots” in colorectal tumor microenvironment, which may synergize with PD1/PDL1 checkpoint blockade antibodies. Thus, our findings suggest that a MAVS cancer gene therapy may offer an alternative approach to activate immunity in “immunologically cold” or “T-cell excluded” tumors.

This abstract is also being presented as Poster A45.

Citation Format: Bin-Jin Hwang, Li-Chung Tsao, Gabriel DeLeon, Junping Wei, Xiao-Yi Yang, Gangjun Lei, Tao Wang, Michael M. Morse, Herbert Kim Lyerly, Zachary Conrad Hartman. Overexpression of MAVS stimulates antitumor immunity and significantly reduces tumor growth of immune-insensitive colorectal cancer in vivo [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr PR2.

DC-CIK as a widely applicable cancer immunotherapy

Introduction: Immunotherapy is now a standard treatment for many malignancies. Although immune checkpoint inhibition has demonstrated substantial efficacy by enhancing T cell activation and function in the tumor microenvironment, adoptive transfer of T and NK cell products promises to provide activated cells capable of immediate and direct tumor destruction. A widely applicable, non-MHC dependent, cellular therapy, consisting of in vitro generated dendritic cells (DC) combined with cytokine-induced killer cells (CIK), is highly efficient to produce from individual patients and has demonstrated safety and efficacy alone or with chemotherapy.Areas covered: We summarize the clinical data from studies of DC-CIK and discuss future research directions.Expert opinion: Patients with a wide variety of tumor types who have received DC-CIK therapy may experience clinical responses. This versatile therapy synergizes with other anti-cancer therapies including chemotherapy and immunotherapy.

CD47 blockade augmentation of trastuzumab antitumor efficacy dependent on antibody-dependent cellular phagocytosis

The HER2-specific monoclonal antibody (mAb), trastuzumab, has been the mainstay of therapy for HER2+ breast cancer (BC) for approximately 20 years. However, its therapeutic mechanism of action (MOA) remains unclear, with antitumor responses to trastuzumab remaining heterogeneous and metastatic HER2+ BC remaining incurable. Consequently, understanding its MOA could enable rational strategies to enhance its efficacy. Using both murine and human versions of trastuzumab, we found its antitumor activity dependent on Fcγ receptor stimulation of tumor-associated macrophages (TAMs) and antibody-dependent cellular phagocytosis (ADCP), but not cellular cytotoxicity (ADCC). Trastuzumab also stimulated TAM activation and expansion, but did not require adaptive immunity, natural killer cells, and/or neutrophils. Moreover, inhibition of the innate immune ADCP checkpoint, CD47, significantly enhanced trastuzumab-mediated ADCP and TAM expansion and activation, resulting in the emergence of a unique hyperphagocytic macrophage population, improved antitumor responses, and prolonged survival. In addition, we found that tumor-associated CD47 expression was inversely associated with survival in HER2+ BC patients and that human HER2+ BC xenografts treated with trastuzumab plus CD47 inhibition underwent complete tumor regression. Collectively, our study identifies trastuzumab-mediated ADCP as an important antitumor MOA that may be clinically enabled by CD47 blockade to augment therapeutic efficacy.

Miniaturized Intracavitary Forward-Looking Ultrasound Transducer for Tissue Ablation

OBJECTIVE

This paper aims to develop a miniaturized forward-looking ultrasound transducer for intracavitary tissue ablation, which can be used through an endoscopic device. The internal ultrasound (US) delivery is capable of directly interacting with the target tumor, resolving adverse issues of currently available US devices, such as unintended tissue damage and insufficient delivery of acoustic power.

METHODS

To transmit a high acoustic pressure from a small aperture (<3 mm), a double layer transducer (1.3 MHz) was designed and fabricated based on numerical simulations. The electric impedance and the acoustic pressure of the actual device was characterized with an impedance analyzer and a hydrophone. Ex vivo tissue ablation tests and temperature monitoring were then conducted with porcine livers.

RESULTS

The acoustic intensity of the transducer was 37.1 W/cm² under 250 V_pp and 20% duty cycle. The tissue temperature was elevated to 51.8 °C with a 67 Hz pulse-repetition frequency. The temperature profile in the tissue indicated that ultrasound energy was effectively absorbed inside the tissue. During a 5-min sonification, an approximate tissue volume of 2.5 × 2.5 × 1.0 mm³ was ablated, resulting in an irreversible lesion.

CONCLUSION

This miniaturized US transducer is a promising medical option for the precise tissue ablation, which can reduce the risk of unintended tissue damage found in noninvasive US treatments.

SIGNIFICANCE

Having a small aperture (2 mm), the intracavitary device is capable of ablating a bio tissue in 5 min with a relatively low electric power (<17 W).

Impact of synchronized anti-PD-1 with Ad-CEA vaccination on inhibition of colon cancer growth

Aim: The purpose of this study was to determine whether addition of anti-PD-1 antibody increased the immunogenicity and anti-tumor activity of Ad-CEA vaccination in a murine model of colon cancer. Methods: Ad-CEA was administered prior to implantation of MC-38-CEA cells followed by administration of anti-PD-1 antibody. CEA-specific T-cell responses were measured by flow cytometry and ELISPOT. Dynamic co-culture of splenocytes with tumor cells was conducted to analyze anti-tumor activities. Tumor infiltration by lymphocytes was measured by IHC. Tumor volume and overall survival were also recorded. Results: Ad-CEA combined with anti-PD-1 antibody showed greater anti-tumor activity compared with either alone. The combination also increased T-cell infiltration but decreased Tregs. Conclusion: Combining Ad-CEA vaccination with anti-PD-1 antibody enhanced anti-tumor activity and immune responses.

White paper on microbial anti-cancer therapy and prevention

In this White Paper, we discuss the current state of microbial cancer therapy. This paper resulted from a meeting ('Microbial Based Cancer Therapy') at the US National Cancer Institute in the summer of 2017. Here, we define 'Microbial Therapy' to include both oncolytic viral therapy and bacterial anticancer therapy. Both of these fields exploit tumor-specific infectious microbes to treat cancer, have similar mechanisms of action, and are facing similar challenges to commercialization. We designed this paper to nucleate this growing field of microbial therapeutics and increase interactions between researchers in it and related fields. The authors of this paper include many primary researchers in this field. In this paper, we discuss the potential, status and opportunities for microbial therapy as well as strategies attempted to date and important questions that need to be addressed. The main areas that we think will have the greatest impact are immune stimulation, control of efficacy, control of delivery, and safety. There is much excitement about the potential of this field to treat currently intractable cancer. Much of the potential exists because these therapies utilize unique mechanisms of action, difficult to achieve with other biological or small molecule drugs. By better understanding and controlling these mechanisms, we will create new therapies that will become integral components of cancer care.

Abstract P3-02-03: Detection of mutations in single tumor cells collected by fine needle aspiration in a mouse xenograft breast cancer model using MALDI-TOF

Background: Breast fine needle aspiration (FNA) is less invasive than a core needle biopsy and reduces the risk of infection or injury to the patient. However, less tissue is available for analysis than with biopsy. The ability to detect and analyze single atypical cells for molecular abnormalities would allow the consideration of more widely adopting FNA for diagnosis. Here we demonstrate the feasibility of this approach in a mouse xenograft model of breast cancer.

Methods: Human-into-mouse MBA-MD-231 breast cancer xenograft tumors were aspirated using a technique that approximates the clinical procedure in patients. Cells from the FNA were prepared by two methods: 1) mixing the aspirate with transfer fluid and spreading onto a Superfrost® Plus slide using RareCyte's AccuCyte® process, and 2) spraying the aspirate directly onto a Superfrost Plus slide, then drying and fixing in ethanol. A single tumor was also disaggregated into suspension, filtered, mixed with transfer fluid and spread on to slides as in method 1 above as a control. Slides were fixed in formalin, stained on an automated immunostainer and imaged using the CyteFinder® digital fluorescence scanning microscope. Tumor cells were identified by positive nuclear, EpCAM, and cytokeratin staining, and negative CD45 staining. Tumor cells were picked from the slides and put into PCR tubes using the CytePicker® module. DNA from individual cells was amplified using the PicoPLEX® (Rubicon) whole genome amplification (WGA) kit. Quality control (QC) of the WGA reactions was performed by PCR of amplicons on eight different chromosomes. Specific gene regions surrounding 5 mutations present in MBA-MD-231 cells were amplified from the WGA products and scored for the mutations using a single PCR reaction iPLEX® Pro panel using the MassARRAY® platform (Agena Bioscience). A lung tumor panel was also run as a negative control.

Results: FNA tumor cells stained with epithelial markers similarly to cells from the disaggregated tumor control and were easily identified. Slides prepared by method 1 above spread into a uniform monolayer making it easier to pick individual cells. Cells from method 2 tended to clump making it more difficult to pick individual cells. Cells were thus picked only from method 1 slides. QC measurements of WGA products from individual cells demonstrated broad genome coverage of amplification; 10 of 14 cells exhibited 7 or more QC products out of 8. Point mutations in four genes (BRAF, KRAS, NF2, and TP53) and a deletion in one gene (CDKN2A) were measured in these cells by iPLEX® Pro chemistry on the MassARRAY® system and found in all cells picked, with all mutations identified in most cells. These mutations and the deletion were not detected in control WBCs.

Conclusions: Individual breast cancer cells were identified in FNA samples from xenograft tumors and molecularly characterized, verifying that the cells identified by positive staining were tumor cells. These results demonstrate the feasibility of detecting and verifying tumor cells in FNA samples in breast and other cancers.

Citation Format: Stilwell JL, Hobeida A, Birse RT, Ericson N, Ramirez AB, Hummel S, Irwin D, Kaldjian EP, Lyerly HK. Detection of mutations in single tumor cells collected by fine needle aspiration in a mouse xenograft breast cancer model using MALDI-TOF [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-02-03.

Abstract B36: Modulating the tumor microenvironment to enhance cancer immunotherapy by inducing phosphatidylserine expression on the tumor surface

Background and Hypothesis: While immune checkpoint blockade, in particular PD-1 or PD-L1 inhibition, has revolutionized cancer immunotherapy, a significant number of patients with solid tumors fail to respond to therapy. An emerging consensus is the need for a local infiltration of immune effector T cells, in combination with PD-1 or PD-L1, for anticancer responses. We are exploring an improved strategy to modulate the tumor microenvironment by targeting phosphatidylserine (PS), which is a phospholipid membrane component maintained on the cytosolic side of the cell membrane in viable cells. When a cell undergoes apoptosis or stress induced by the microenvironment, PS is no longer restricted to the cytosolic domain and gets transposed to the extracellular surface where it serves a variety of functions, including as a ligand for another immune checkpoint, TIM-3. In fact, PS-targeting antibodies induce immunity against weakly immunogenic tumor cells (He at al, 2009), and may serve to enhance anti-cancer immunotherapy. Chemotherapy and radiation therapy are often used to treat cancers. In addition, photodynamic therapy using a photosensitizer conjugated with a target specific molecule has been recognized as an emerging therapeutic strategy. Therefore, we sought to determine the expression of PS following treatment with chemotherapy, radiation, or photodynamic therapy, and to determine if the addition of a PS-targeting antibody could augment antitumor response, especially in combination with PD-1 inhibition.

Methods and Results: We first confirmed the upregulation of PS on malignant human cells following treatment with chemotherapy by FACS analysis using PS-targeting antibody mch1N11. PS expression was increased (50.2% positive compared to 5.0% in untreated cells) after 18 h of incubation with etoposide (25µM). We then tested PS expression on murine triple negative breast cancer cell lines (E0771-OVA, 4T1) at days 1, 2, and 4 after a single dose of X-ray (30, 40, or 50 Gy). E0771-OVA cells showed increased PS expression at day 2, while 4T1 cell lines increased PS expression at day 4. E0771-OVA cells were also irradiated using a more conventional schedule, specifically daily administration (6 Gy/day 5 days), leading to increase PS expression. Additionally, we tested PS expression on E0771-OVA cells after photodynamic therapy using HS201, which is a synthesized photosensitizer compound constructed of verteporfin and HSP 90 inhibitor. PS expression increased at day 1 when the cells were treated with a single dose of laser (10 or 60J) after 30 minutes conjugation of HS201 (1 or 10 μM).

After confirming upregulation of PS by chemotherapy, radiotherapy, and photodynamic therapy, we next tested the combination of PS-targeting mAb mch1N11 with chemotherapy in vivo. We treated C57BL/6 mice bearing E0771-OVA tumors with paclitaxel (PTX), PS-targeting mAb mch1N11, anti-PD-L1 Ab, or combination. As single agents, both mch1N11 and anti-PD-L1 mAbs showed tumor growth suppression; however, combination of those two and 3 combination showed stronger effect. On the other hand, PTX didn't seem to add any additional effect.

Conclusions: PS expression is upregulated by chemotherapy, radiotherapy, and photodynamic therapy in vitro. A combination therapy blocking PS by PS-targeting mAb and immune checkpoint blockade with anti-PD-L1 mAb appears superior to single agent therapy. Our future plan is to investigate the effect of local irradiation or photodynamic therapy combined with PS-targeting mAb and anti-PD-L1 Ab.

Citation Format: Kensuke Kaneko, Takuya Osada, Bruce D. Freimark, Herbert Kim Lyerly. Modulating the tumor microenvironment to enhance cancer immunotherapy by inducing phosphatidylserine expression on the tumor surface. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B36.

Abstract P2-04-27: CTLA-4 and PD-1 checkpoint inhibitors enhance individually tailored adaptive anti-tumor immune responses to overcome tumor immunosuppression and effectively treat triple-negative breast cancer

Despite a lack of unifying drivers in Triple-Negative Breast Cancer (TNBC), our lab and others have uncovered that these cancers have elevated expression of inflammatory genes and immunosuppressive molecules (i.e. PD-L1), as well as elevated numbers of infiltrating immune cells (including CD8+ T-cells and Foxp3+ T-regulatory cells) which suggests the therapeutic potential for single and combinations of checkpoint blockade antibodies. While early trials with PD-1 inhibitors have been encouraging for TNBC, only a fraction of treated patients respond to this therapy. To test and define the mechanisms that govern responses, we explored the utility and mechanistic basis of both PD-1 and CTLA-4 inhibition in generating tumor-specific immunity in an established murine model of TNBC.

Consistent with patient samples, we found TNBC tumors from our model exhibited elevated PD-1+ expressing CD8+ T-cell infiltrates, Foxp3+ T-regulatory cell infiltrates (~66% of CD4+ TILs), as well as highly elevated tumor cell expression of PD-L1. We also found that while TNBC cells were easily killed by T-cell in vitro, TNBC tumors were highly immuno-suppressive and resistant to antigen-specific T-cell attack in vivo, even after adoptive transfer of up to 5x10E6 tumor-specific T-cells.

However, we found that both CTLA-4 and PD-1 antibodies could curtail this immunosuppression to different degrees and through alternate mechanisms. Specifically, we found that CTLA-4 antibody mediated anti-tumor immunity through the elimination and blockade of Foxp3+ T-regulatory cells in the tumor microenvironment, which allow for potent T-cell expansion. Conversely, PD-1 antibodies elicited anti-tumor immunity through blockade of PDL1/PD1 signaling between tumor cells and T-cells in the TNBC tumor microenvironment that allowed for a more modest expansion of individually tailored T-cell specific clones in vivo.

Strikingly, the combination of these antibodies and their alternate mechanisms of action resulted in greatly enhanced anti-tumor responses and led to regression of ~80% of tumors. This was accompanied by an augmented infiltration of T-cells into the tumor microenvironment and significantly enhanced systemic tumor-specific T-cell responses, which appear to be emergent properties of dual CTLA-4/PD-1 antibody treatment.

However, we found that these treatments did not expand a common tumor-specific T-cell clone, despite adoptive transfer of identical tumor-specific immunodominant T-cells into mice after tumor implantation. Thus, despite our use of a highly homogeneous model utilizing genetically identical mice implanted with an identical tumor line bearing a unique tumor antigen under identical conditions, the tumor-specific T-cell responses were highly unique for each individual tumor. Collectively, our study suggest that dual blockade could be an effective therapeutic clinical strategy against TNBC and further suggest the utility of monitoring systemic immune response and TCR expansion of TILs as the most useful correlates in clinical studies utilizing CTLA-4 and PD-1 antibodies.

Citation Format: Hartman ZC, Crosby EJ, Wei J-P, Yang X-Y, Lei G-J, Wang T, Liu C-X, Agarwal P, Morse MS, Lyerly HK. CTLA-4 and PD-1 checkpoint inhibitors enhance individually tailored adaptive anti-tumor immune responses to overcome tumor immunosuppression and effectively treat triple-negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-27.

The prognostic value of peripheral CD4+CD25+ T lymphocytes among early stage and triple negative breast cancer patients receiving dendritic cells-cytokine induced killer cells infusion

Objective

This study aimed to assess the prognostic value of CD4⁺CD25⁺ T lymphocyte in peripheral blood among breast cancer patients treated with adoptive T lymphocytes immunotherapy.

Methods

217 patients participated in the follow-up study. CD4⁺CD25⁺ proportion was measured by flow cytometry in peripheral T cells. The median survival was estimated by Kaplan-Meier curve, Log-rank test and Cox hazard proportion regression model, between groups of CD4⁺CD25⁺ proportion more than 5% and less than or equal to 5% in peripheral T cells.

Results

Peripheral CD4⁺CD25⁺ T lymphocytes had not a relationship with progression-free survival. It was featured that above 5% peripheral CD4⁺CD25⁺ proportion of T cells was related with the median overall survival by a shorten of 51 months (p < 0.05) with the HR 1.65 (95%CI 1.04, 2.62). Above 5% CD4⁺CD25⁺proportion of T cells produced the HR to be 1.76 (95%CI 1.07, 2.87) In stage 0-II patients, and 3.59 (95%CI 1.05, 12.29) in triple negative breast cancer patients.

Conclusion

Cellular immunity restoration recovered by adoptive T cell infusions which resulted in less proportion of peripheral CD4⁺CD25⁺T lymphocytes could be a potential prognostic indicator among early stage and triple negative patients.

Abstract P4-09-16: A monoclonal antibody with exceptional specificity across major breast cancer subtypes

Background: Breast cancer (BC) remains the second leading cause of cancer-related deaths for women in the United States and is recognized to be a heterogeneous disease. Advances in technologies such as whole genome sequencing are leading the way to precision medicine and the leading researchers are envisioning personalized therapies in the not too distant future. However, given the diversity of cancer cell populations, that remains a challenging task at best. The tumor form of MUC1 (designated tMUC1), a transmembrane glycoprotein, is aberrantly glycosylated and overexpressed in ∼95% of BC. We have developed an antibody (TAB004) that specifically recognizes tMUC1 across all major subtypes of BC and importantly does not recognize normal breast epithelia. This is a significant development in light of the challenges faced in treating triple negative BC.

Methods: A panel of thirty BC cell lines was obtained from ATCC. The following techniques were used to assess the specificity of TAB 004 to the major subtypes based on ER, PR and Her2 expression: 1) Flow cytometry to quantify membrane bound expression of tMUC1 using Cy7-conjugated TAB004; 2) Western blotting to detect molecular weight patterns of tMUC1 in whole cell lysate; 3) A TAB004 based GMP-grade ELISA kit to measure shed tMUC1 in the supernatant and 4) In vivo imaging of tumors in mice using TAB 004 conjugated to Indocyanine Green (ICG). Specificity and sensitivity was further confirmed using primary human serum and tissue samples from all major BC subtypes obtained from bio-repositories at Duke University Cancer Center, Fox Chase Cancer Center and Carolinas Health Care System. Shed tMUC1 in serum samples were tested using the TAB 004 ELISA kit and tissue sections were analyzed using immunohistochemical (IHC) staining with TAB 004 conjugated to HRP.

Results: 1) Flow cytometry data shows that TAB 004 recognized tMUC1 on all major BC subtypes: 25 out of 30 BC cell lines tested had higher expression than a normal epithelial breast cell line; 2) Western blotting also detected tMUC1 on all BC subtypes with distinct molecular weight patterns; 3) ELISA showed high levels of shed tMUC1 by most BC cells and correlated with bound/cytoplasmic levels. 4) In vivo imaging shows clear localization of TAB004-ICG to the tumors expressing tMUC1. Primary human breast cancer patient data shows that shed tMUC1 was detected in the serum obtained from all major BC subtypes and showed statistically significant differentiation from normal/benign. IHC results show strong tMUC1 expression in malignant tissue with excellent differentiation from adjacent normal tissue.

Conclusion: TAB004 antibody's extraordinary specificity across major BC subtypes has been confirmed with flow cytometry, western blotting, ELISA and Immunohistochemistry. A number of clinical applications are under development: (a) An ELISA test as a supplement to mammography for the early detection of BC in women with dense breasts; (b) serum monitoring during treatment and to detect disease recurrence; and, (c) targeted antibody-drug/antibody-imaging agent based therapies and imaging modalities particularly for triple negative BC.

Citation Format: Das Roy L, Zhou R, Dillon L, Moore LJ, Puri R, Marks JR, Lyerly HK, Mukherjee P. A monoclonal antibody with exceptional specificity across major breast cancer subtypes. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-16.

Breast Cancer Challenges and Screening in China: Lessons From Current Registry Data and Population Screening Studies

BACKGROUND

As one of its responses to the increasing global burden of breast cancer (BC), China has deployed a national registration and BC screening campaign. The present report describes these programs and the initial results of these national BC control strategies, highlighting the challenges to be considered.

MATERIALS AND METHODS

The primary BC incidence and prevalence data were obtained from the Chinese National Central Cancer Registry. MapInfo software was used to map the geographic distribution and variation. The time trends were estimated by the annual percentage of change from 2003 to 2009. The description of the screening plans and preliminary results were provided by the Ministry of Health.

RESULTS

Chinese cancer registries were primarily developed and activated in the East and Coastal regions of China, with only 12.5% of the registries located in West China. Geographic variation was noted, with the incidence of BC higher in North China than in South China and in urban areas compared with rural areas. Of great interest, these registries reported that the overall BC incidence has been increasing in China, with an earlier age of onset compared with Western countries and a peak incidence rate at age 50. In response to this increasing incidence and early age of onset, BC screening programs assessed 1.46 million women aged 35-59 years, using clinical breast examinations and ultrasound as primary screening tools between 2009 and 2011. The diagnostic rate for this screening program was only 48.0/10(5) with 440 cases of early stage BC. Early stage BC was detected in nearly 70% of screened patients. Subsequently, a second-generation screening program was conducted that included older women aged 35-64 years and an additional 6 million women were screened.

CONCLUSION

The cancer registration system in China has been uneven, with a greater focus on East rather than West China. The data from these registries demonstrate regional variation, an increasing BC incidence, and an early age of onset. The 2009 to 2011 BC screening program targeting women aged 35-59 years had a low detection rate that resulted in a second-generation screening program that extended the cohort size and ages screened to 35-64 years.

IMPLICATIONS FOR PRACTICE

Cancer registration has been active in China for decades; however, a national survey of registries has not been routinely reported. This study used MapInfo to describe the reported data and found asymmetric registration activities, geographic variations in breast cancer (BC) burdens, and an increasing incidence with a peak at age 50. The initial Chinese BC screening programs focused on a relatively young population of women aged 35-59 years and had a low detection rate, but 69.7% of patients had early stage BC. Older women were included in the second-generation screening programs, and an additional 6 million women were screened. Consideration of regional variations and age is necessary to optimize the efficiency and utility of BC screening in China, with the ultimate goal to reduce BC mortality.

Perhexiline promotes HER3 ablation through receptor internalization and inhibits tumor growth

INTRODUCTION

Human epidermal growth factor receptor HER3 has been implicated in promoting the aggressiveness and metastatic potential of breast cancer. Upregulation of HER3 has been found to be a major mechanism underlying drug resistance to EGFR and HER2 tyrosine kinase inhibitors and to endocrine therapy in the treatment of breast cancer. Thus, agents that reduce HER3 expression at the plasma membrane may synergize with current therapies and offer a novel therapeutic strategy to improve treatment.

METHODS

We devised an image-based screening platform using membrane localized HER3-YFP to identify small molecules that promote HER3 internalization and degradation. In vitro and in vivo tumor models were used to characterize the signaling effects of perhexiline, an anti-anginal drug, identified by the screening platform.

RESULTS

We found perhexiline, an anti-anginal drug, selectively internalized HER3, decreased HER3 expression, and subsequently inhibited signaling downstream of HER3. Consistent with these results, perhexiline inhibited breast cancer cell proliferation in vitro and tumor growth in vivo.

CONCLUSIONS

This is the first demonstration that HER3 can be targeted with small molecules by eliminating it from the cell membrane. The novel approach used here led to the discovery that perhexiline ablates HER3 expression, and offers an opportunity to identify HER3 ablation modulators as innovative therapeutics to improve survival in breast cancer patients.

Elevated level of peripheral CD8(+)CD28(-) T lymphocytes are an independent predictor of progression-free survival in patients with metastatic breast cancer during the course of chemotherapy

PURPOSE

Suppression of cellular immunity resulting from tumorigenesis and/or therapy might promote cancer cells' growth, progression and invasion. Here, we explored whether T lymphocyte subtypes from peripheral blood of metastatic breast cancer (MBC) female patients could be used as alternative surrogate markers for cancer progress. Additionally, plasma levels of interleukin (IL)-2, IL-4, IL-6, IL-10, IFN-γ, and transforming growth factor-β1 were quantitated from MBC and healthy volunteers.

EXPERIMENTAL DESIGN

This study included 89 female MBC patients during the post-salvage chemotherapy follow-up and 50 age- and sex-matched healthy volunteers as control. The percentages of T lymphocyte subpopulations from peripheral blood and plasma levels of cytokines were measured.

RESULTS

Both CD8(+)CD28(-) and CD4(+)CD25(+) were elevated in MBC patients compared to the control cohort (P < 0.05). In contrast, CD3(+) and CD8(+)CD28(+)cells were significantly lower in MBC patients (P < 0.0001, P = 0.045, respectively). MBC patients had elevated levels of immunosuppressive cytokines IL-6 and IL-10. Patients with elevated CD8(+)CD28(-) and CD4(+)CD25(+) cells showed increased levels of IL-6, and only patients with elevated CD8(+)CD28(-) had decreased interferon-γ. Univariate analysis indicated increased CD3(+)CD4(+) or CD8(+)CD28(+)correlated with prolonged progression-free survival (PFS), while elevated CD8(+)CD28(-)associated with shorten PFS. The percent of CD8(+)CD28(-) T lymphocytes is an independent predictor for PFS through multivariate analysis.

CONCLUSIONS

This study suggests that progressive elevated levels of CD8(+)CD28(-) suppressor T lymphocytes represent a novel independent predictor of PFS during post-chemotherapy follow-up.

Abstract 5298: Two distinctive single nucleotide polymorphisms determine liver metastases responses to docetaxel plus thiotepa for metastatic breast cancer patients

The successful predictively treatment of metastatic breast cancer (MBC) remains a major challenge. Until now there is no definite marker to distinguish responder from non-responder and more and more important, metastasis occurred within different organs lead to serious variations of overall survival. In this study, paclitaxel and anthracyclines pretreated153 patients with MBC received 606 cycles of docetaxel plus thiotepa. 65 of 153 patients were concurrently diagnosed as MBC involved liver metastasis (LM). Among 153 patients, the response were 1 complete response (CR) (0.7%), 25 partial responses (PR) (16.3%), 73 stable diseases (SD) (47.7%), 46 progressive diseases (PD) (30.1%) and 8 unevaluable(5.2%). For LM patients, the localized liver response were 2 CR (3.1%), 20 PR (30.8%), 16 SD (24.6%), 22 PD (33.8%),5 unevaluable (7.7%). Median PFS and OS for both entire and LM subgroup were 6.5 (95% CI, 5.6 to 7.4) versus 4.2 (95%CI, 2.3-6.1), and 20.0 (95% CI, 15.6 to 24.4) versus 14.2 (95%CI, 9.5-18.9) months respectively. 79 SNPs in CYP450, whose minor allele frequency were ≥ 10% were genotyped. There was no significant difference of SNPs in therapeutic responses, PFS or OS. Of importance, there were two distinctive SNPs, rs2277119 and rs4646487 *2/*3 alleles, which tended to have the better liver metastases response than *1 when choosing a false discovery rate as 12%. It seemed that docetaxel plus thiotepa might be regarded as an active specific regimen for MBC with liver metastasis. The generation of conceptually specific chemotherapy targeting the organ with cancer metastasis should be considered in the future.

Citation Format: Jing Yu, Ningning Dong, Ying Yan, Bin Shao, Lijun Di, Guohong Song, Li Che, Jun Jia, Hanfang Jiang, Xu Liang, Yulin Zhu, Chaoying Wang, Jie Zahng, Budong Zhu, Xinna Zhou, Xiaoli Wang, Huabing Yang, Jun Ren, Herbert Kim Lyerly. Two distinctive single nucleotide polymorphisms determine liver metastases responses to docetaxel plus thiotepa for metastatic breast cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5298. doi:10.1158/1538-7445.AM2013-5298

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Selections of appropriate regimen of high-dose chemotherapy combined with adoptive cellular therapy with dendritic and cytokine-induced killer cells improved progression-free and overall survival in patients with metastatic breast cancer: reargument of such contentious therapeutic preferences

BACKGROUND

We hypothesized that combination of dendritic cell (DC) with autologous cytokine-induced killer (CIK) immunotherapy in setting of high-dose chemotherapy (HDC) would be effective for selected metastatic breast cancer (MBC) patients.

PATIENTS AND METHODS

Our previous work showed thiotepa could eradicate breast cancer stem cells. From 2004 to 2009, 79 patients received standard dose chemotherapy (SDC) of 75 mg/m(2) docetaxel and 75 mg/m(2) thiotepa versus 87 patients of HDC + DC/CIK: 120 mg/m(2) docetaxel to mobilize peripheral CD34(+) progenitor cells, a sequence of HDC (120 mg/m(2) docetaxel, plus 175 mg/m(2) thiotepa) + DC/CIK, with or without 400 mg/m(2) carboplatin depending upon bone marrow function. The endpoints were response rates (RR), progression-free survival (PFS), and overall survival (OS).

RESULTS

Compared with SDC, PFS and OS were improved in HDC + DC/CIK (median PFS 10.2 vs. 3.7 months, P < 0.001; median OS 33.1 vs. 15.2 months, P < 0.001). Patients of pre-menopausal, HDC as first-line treatment after metastasis, or with visceral metastasis showed prolonged PFS and OS. SDC group also achieved the similar response as previous reports.

CONCLUSION

Our study demonstrated the novel combination of HDC with DC/CIK to be an effective choice for the selected MBC population, in which choosing appropriate chemo regimens played important roles, and also specific HDC regimen plus DC/CIK immunotherapy showed the clinical benefits compared with chemotherapy alone.

Abstract P4-08-07: Novel insight into the tumor “flare” phenomenon and lapatinib resistance

BACKGROUND: Resistance to lapatinib generally develops in approximately half of patients within one year of initiating treatment. When lapatinib is withdrawn, there is often a rapid progression of disease which is associated with high mortality rates. This “flare” phenomenon has also been observed upon discontinuation of other tyrosine kinase inhibitors (TKIs) in lung cancer, renal cell carcinoma, and gastrointestinal stromal tumors.

METHODS: Using the HER2+ cell lines SKBR3 and BT474, we developed both in vitro and in vivo models demonstrating lapatinib resistance and the tumor “flare” phenomenon. Parental HER2+ cell lines were gradually exposed to increasing doses of lapatinib (100nM to 5uM) to develop a lapatinib-resistant form which was ultimately maintained in 1uM of lapatinib. Lapatinib-”released” cell lines were developed by removing lapatinib exposure from resistant cell lines and allowing the cells to grow for at least two weeks. Cell lines were grown in vitro using traditional monolayer cell culturing techniques and mammosphere technology. A comprehensive analysis of parental, lapatinib-resistant, and lapatinib-released cell lines was performed using microscopy, protein/phosphoprotein analysis, cell cycle, cancer stem cell markers by FACS, and invasion assays. Parental cells served as the control in all experiments. In vivo models were performed by injecting 10,000 cells of parental, resistant, and released cell lines in the mammary fat pads of SCID mice. Tumors were surgically resected after approximately sixty days and volume recorded. All experiments were repeated three times and calculated for statistical significance.

RESULTS: Cell cycle analysis and proliferation assays demonstrate that lapatinib-resistant and released cell lines continue to proliferate despite the addition of 1uM lapatinib. Released cells also demonstrate less of a response to retreatment with lapatinib. Tumor volume of lapatinib-released cell lines were significantly larger than parental and resistant counterparts [parental: 39.9mm3, SD 9.48; resistant: 71.8mm3, SD 62.33; released: 943.4mm3, SD 100.1] and this difference was statistically significant (p &lt; 0.01). After three series of passages, mammosphere forming efficiency (MFE) was higher among lapatinib-released cell lines [parental: 1.03%; resistant: 1.93% released: 7.23%] and was statistically significant (p &lt;0.01). Lapatinib-released mammosphere phenotypes appeared larger and less organized than the parental and resistant counterparts. MFE did not correlate with ALDH expression by FACS, and expression varied based on cell line. Western blot analysis revealed loss of E-cadherin among lapatinib-released cells which was not demonstrated in parental or resistant counterparts. Invasion assays demonstrated increased migration among resistant and released cell lines.

CONCLUSIONS: We demonstrate the first in vitro and in vivo models of the tumor “flare” phenomenon using HER2+ breast cancer cell lines. This model demonstrates that lapatinib-resistant cells released from the exposure to lapatinib are propelled into a unique and more aggressive phenotype. This model has potential to elucidate new mechanisms of resistance to TKI therapy and provide novel preclinical data that may help in the understanding of disease progression.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-08-07.

Specific genetic polymorphisms of IL10-592 AA and IL10-819 TT genotypes lead to the key role for inducing docetaxel-induced liver injury in breast cancer patients

AIM

This study was designed to explore the genetic polymorphism of IL-10 (-1082A/G, -592A/C, -819T/C), TNF-α (-308G/A) with susceptibility to docetaxel-induced liver injury (DILI) in Chinese breast cancer patients.

METHODS

The targeted genetic polymorphisms of IL10-1082G/A, IL10-592A/C, IL10-819T/C, TNF-308G/A from 40 patients with DILI were assayed by matrix-assisted laser desorption/ionization-time of flight of Sequenom.

RESULTS

AA genotype of IL10-592 and TT of IL10-819 significantly increased incidence of DILI (P = 0.005, OR = 3.137). No differences of TNF gene polymorphism between the two groups were seen.

CONCLUSION

The genetic polymorphism of the IL10-592A/C AA genotype and IL10-819T/C TT genotype was predominantly conferred to the incidence of docetaxel-induced liver injury.

Non-genetic risk factors and predicting efficacy for docetaxel--drug-induced liver injury among metastatic breast cancer patients

BACKGROUND AND AIM

Docetaxel has been chosen as one of the most popular anticancer drugs in the treatment of breast cancer for more than a decade. There is increasingly awareness for the occurrence of docetaxel and/or docetaxel-drug-induced liver injury (DILI), although the underlying mechanism of occurrence and its risk factors remain unclear.

METHODS

We conducted a retrospective cohort study to identify non-genetic risk factors for docetaxel-DILI among 647 metastasis breast cancer patients treated with docetaxel-containing regimens.

RESULTS

Sixty-seven (10.36%) patients were diagnosed as docetaxel-DILI. By logistic regression analysis, premenopausal status (odds ratio [OR][95% confidence interval {CI}] = 2.24 [1.30-3.87]), past hepatitis B virus (HBV) infections (OR [95% CI] = 4.23 [1.57-11.42]), liver metastasis (OR [95% CI] = 3.70 [2.16-6.34]). The predominant occurrence of DILI was seen in groups with docetaxel combination regimens. (OR [95% CI] = 2.66 [1.59-4.55]). The potential increasing occurrence of docetaxel-DILI was associated with multiple risk factors in an exposure-response manner (P < 0.001), and patients with more than three risk factors would be exposed to a 36.61-fold risk of DILI (95% CI = 10.18-131.62). Further analysis by the risk score and area under the receiver-operator characteristic curve (AUC) showed that those four factors contributed to an AUC of 0.7536 (95% CI = 0.70-0.81), with a predictive sensitivity of 74.63% and specificity of 65.17%.

CONCLUSIONS

Docetaxel-DILI with a relatively higher incidence should be addressed among metastatic breast cancer patients. Four predominant risk factors, including premenopausal status, past HBV infection, liver metastasis, and docetaxel combination regimens, were potential predicators for DILI.

Targeting GLI1 expression in human inflammatory breast cancer cells enhances apoptosis and attenuates migration

Background:

Inflammatory breast cancer (IBC) is an aggressive subtype of breast cancer with distinct molecular profiles. Gene expression profiling previously identified sonic hedgehog (SHH) as part of a gene signature that is differentially regulated in IBC patients.

Methods:

The effects of reducing GLI1 levels on protein expression, cell proliferation, apoptosis and migration were determined by immunoblots, MTT assay, Annexin-V/PI assay and conventional and automated cell migration assays.

Results:

Evaluation of a panel of breast cancer cell lines revealed elevated GLI1 expression, typically a marker for hedgehog-pathway activation, in a triple-negative, highly invasive IBC cell line, SUM149 and its isogenic-derived counterpart rSUM149 that has acquired resistance to ErbB1/2 targeting strategies. Downregulation of GLI1 expression in SUM149 and rSUM149 by small interfering RNA or a small molecule GLI1 inhibitor resulted in decreased proliferation and increased apoptosis. Further, GLI1 suppression in these cell lines significantly inhibited cell migration as assessed by a wound-healing assay compared with MCF-7, a non-invasive cell line with low GLI1 expression. A novel high-content migration assay allowed us to quantify multiple effects of GLI1 silencing including significant decreases in cell distance travelled and linearity of movement.

Conclusion:

Our data reveal a role for GLI1 in IBC cell proliferation, survival and migration, which supports the feasibility of targeting GLI1 as a novel therapeutic strategy for IBC patients.

ADAM metallopeptidase domain 17 (ADAM17) is naturally processed through major histocompatibility complex (MHC) class I molecules and is a potential immunotherapeutic target in breast, ovarian and prostate cancers

Selection of suitable antigens is critical for the development of cancer vaccines. Most desirable are over-expressed cell surface proteins that may serve as targets for both antibodies and T cells, thus maximizing a concerted immune response. Towards this goal, we characterized the relevance of tumour necrosis factor-α-converting enzyme (ADAM17) for such targeted therapeutics. ADAM17 is one of the several metalloproteinases that play a key role in epidermal growth factor receptor (EGFR) signalling and has recently emerged as a new therapeutic target in several tumour types. In the present study, we analysed the expression profile of ADAM17 in a variety of normal and cancer cells of human origin and found that this protein is over-expressed on the surface of several types of cancer cells compared to the normal counterparts. Furthermore, we analysed the presentation of a human leucocyte antigen (HLA)-A2-restricted epitope from ADAM17 protein to specific T cells established from normal donors as well as ovarian cancer patients. Our analysis revealed that the HLA-A2-restricted epitope is processed efficiently and presented by various cancer cells and not by normal cells. Tumour-specific T cell activation results in the secretion of both interferon-γ and granzyme B that can be blocked by HLA-A2 specific antibodies. Collectively, our data present evidence that ADAM17 can be a potential target antigen to devise novel immunotherapeutic strategies against ovarian, breast and prostate cancer.

MLH1 expression sensitises ovarian cancer cells to cell death mediated by XIAP inhibition

BACKGROUND

The X-linked inhibitor of apoptosis protein (XIAP), an endogenous apoptosis suppressor, can determine the level of caspase accumulation and the resultant response to apoptosis-inducing agents such as cisplatin in epithelial ovarian cancer (EOC). In addition, the mismatch repair protein, hMLH1, has been linked to DNA damage-induced apoptosis by cisplatin by both p53-dependent and -independent mechanisms.

METHODS

In this study, hMLH1 expression was correlated with clinical response to platinum drugs and survival in advanced stage (III-IV) EOC patients. We then investigated whether MLH1 loss was a determinant in anti-apoptosis response to cisplatin mediated by XIAP in isogenic and established EOC cell lines with differential p53 status.

RESULTS

The percentage of cells undergoing cisplatin-induced cell killing was higher in MLH1-proficient cells than in MLH1-defective cells. In addition, the presence of wild-type hMLH1 or hMLH1 re-expression significantly increased sensitivity to 6-thioguanine, a MMR-dependent agent. Cell-death response to 6-thioguanine and cisplatin was associated with significant proteolysis of MLH1, with XIAP destabilisation and increased caspase-3 activity. The siRNA-mediated inhibition of XIAP increased MLH1 proteolysis and cell death in MLH1-proficient cells but not in MLH1-defective cells.

CONCLUSION

These data suggest that XIAP inhibitors may prove to be an effective means of sensitising EOC to MLH1-dependent apoptosis.