Publications by authors named "Alexandria P Cogdill"

21 Publications

  • Page 1 of 1

The human tumor microbiome is composed of tumor type-specific intracellular bacteria.

Science 2020 05;368(6494):973-980

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.

Bacteria were first detected in human tumors more than 100 years ago, but the characterization of the tumor microbiome has remained challenging because of its low biomass. We undertook a comprehensive analysis of the tumor microbiome, studying 1526 tumors and their adjacent normal tissues across seven cancer types, including breast, lung, ovary, pancreas, melanoma, bone, and brain tumors. We found that each tumor type has a distinct microbiome composition and that breast cancer has a particularly rich and diverse microbiome. The intratumor bacteria are mostly intracellular and are present in both cancer and immune cells. We also noted correlations between intratumor bacteria or their predicted functions with tumor types and subtypes, patients' smoking status, and the response to immunotherapy.
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http://dx.doi.org/10.1126/science.aay9189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7757858PMC
May 2020

Combination anti-CTLA-4 plus anti-PD-1 checkpoint blockade utilizes cellular mechanisms partially distinct from monotherapies.

Proc Natl Acad Sci U S A 2019 11 21;116(45):22699-22709. Epub 2019 Oct 21.

Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030;

Immune checkpoint blockade therapy targets T cell-negative costimulatory molecules such as cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 (PD-1). Combination anti-CTLA-4 and anti-PD-1 blockade therapy has enhanced efficacy, but it remains unclear through what mechanisms such effects are mediated. A critical question is whether combination therapy targets and modulates the same T cell populations as monotherapies. Using a mass cytometry-based systems approach, we comprehensively profiled the response of T cell populations to monotherapy and combination anti-CTLA-4 plus anti-PD-1 therapy in syngeneic murine tumors and clinical samples. Most effects of monotherapies were additive in the context of combination therapy; however, multiple combination therapy-specific effects were observed. Highly phenotypically exhausted cluster of differentiation 8 (CD8) T cells expand in frequency following anti-PD-1 monotherapy but not combination therapy, while activated terminally differentiated effector CD8 T cells expand only following combination therapy. Combination therapy also led to further increased frequency of T helper type 1 (Th1)-like CD4 effector T cells even though anti-PD-1 monotherapy is not sufficient to do so. Mass cytometry analyses of peripheral blood from melanoma patients treated with immune checkpoint blockade therapies similarly revealed mostly additive effects on the frequencies of T cell subsets along with unique modulation of terminally differentiated effector CD8 T cells by combination ipilimumab plus nivolumab therapy. Together, these findings indicate that dual blockade of CTLA-4 and PD-1 therapy is sufficient to induce unique cellular responses compared with either monotherapy.
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http://dx.doi.org/10.1073/pnas.1821218116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842624PMC
November 2019

The Impact of Intratumoral and Gastrointestinal Microbiota on Systemic Cancer Therapy.

Trends Immunol 2018 11;39(11):900-920

Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA; These authors contributed equally to this work. Electronic address:

The human microbiome is a complex aggregate of microorganisms, and their genomes exert a number of influences crucial to the metabolic, immunologic, hormonal, and homeostatic function of the host. Recent work, both in preclinical mouse models and human studies, has shed light on the impact of gut and tumor microbiota on responses to systemic anticancer therapeutics. In light of this, strategies to target the microbiome to improve therapeutic responses are underway, including efforts to target gut and intratumoral microbes. Here, we discuss mechanisms by which microbiota may impact systemic and antitumor immunity, in addition to outstanding questions in the field. A deeper understanding of these is critical as we devise putative strategies to target the microbiome.
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http://dx.doi.org/10.1016/j.it.2018.09.007DOI Listing
November 2018

Checkpoint Blockade Reverses Anergy in IL-13Rα2 Humanized scFv-Based CAR T Cells to Treat Murine and Canine Gliomas.

Mol Ther Oncolytics 2018 Dec 28;11:20-38. Epub 2018 Aug 28.

Center for Cellular Immunotherapies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.

We generated two humanized interleukin-13 receptor α2 (IL-13Rα2) chimeric antigen receptors (CARs), Hu07BBz and Hu08BBz, that recognized human IL-13Rα2, but not IL-13Rα1. Hu08BBz also recognized canine IL-13Rα2. Both of these CAR T cell constructs demonstrated superior tumor inhibitory effects in a subcutaneous xenograft model of human glioma compared with a humanized EGFRvIII CAR T construct used in a recent phase 1 clinical trial (ClinicalTrials.gov: NCT02209376). The Hu08BBz demonstrated a 75% reduction in orthotopic tumor growth using low-dose CAR T cell infusion. Using combination therapy with immune checkpoint blockade, humanized IL-13Rα2 CAR T cells performed significantly better when combined with CTLA-4 blockade, and humanized EGFRvIII CAR T cells' efficacy was improved by PD-1 and TIM-3 blockade in the same mouse model, which was correlated with the levels of checkpoint molecule expression in co-cultures with the same tumor . Humanized IL-13Rα2 CAR T cells also demonstrated benefit from a self-secreted anti-CTLA-4 minibody in the same mouse model. In addition to a canine glioma cell line (J3T), canine osteosarcoma lung cancer and leukemia cell lines also express IL-13Rα2 and were recognized by Hu08BBz. Canine IL-13Rα2 CAR T cell was also generated and tested by co-culture with canine tumor cells and in an orthotopic model of canine glioma. Based on these results, we are designing a pre-clinical trial to evaluate the safety of canine IL-13Rα2 CAR T cells in dog with spontaneous IL-13Rα2-positive glioma, which will help to inform a human clinical trial design for glioblastoma using humanized scFv-based IL-13Rα2 targeting CAR T cells.
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http://dx.doi.org/10.1016/j.omto.2018.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174845PMC
December 2018

Disruption of TET2 promotes the therapeutic efficacy of CD19-targeted T cells.

Nature 2018 06 30;558(7709):307-312. Epub 2018 May 30.

Center for Cellular Immunotherapies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Cancer immunotherapy based on genetically redirecting T cells has been used successfully to treat B cell malignancies. In this strategy, the T cell genome is modified by integration of viral vectors or transposons encoding chimaeric antigen receptors (CARs) that direct tumour cell killing. However, this approach is often limited by the extent of expansion and persistence of CAR T cells. Here we report mechanistic insights from studies of a patient with chronic lymphocytic leukaemia treated with CAR T cells targeting the CD19 protein. Following infusion of CAR T cells, anti-tumour activity was evident in the peripheral blood, lymph nodes and bone marrow; this activity was accompanied by complete remission. Unexpectedly, at the peak of the response, 94% of CAR T cells originated from a single clone in which lentiviral vector-mediated insertion of the CAR transgene disrupted the methylcytosine dioxygenase TET2 gene. Further analysis revealed a hypomorphic mutation in this patient's second TET2 allele. TET2-disrupted CAR T cells exhibited an epigenetic profile consistent with altered T cell differentiation and, at the peak of expansion, displayed a central memory phenotype. Experimental knockdown of TET2 recapitulated the potency-enhancing effect of TET2 dysfunction in this patient's CAR T cells. These findings suggest that the progeny of a single CAR T cell induced leukaemia remission and that TET2 modification may be useful for improving immunotherapies.
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http://dx.doi.org/10.1038/s41586-018-0178-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6320248PMC
June 2018

The Rationale and Emerging Use of Neoadjuvant Immune Checkpoint Blockade for Solid Malignancies.

Ann Surg Oncol 2018 Jul 2;25(7):1814-1827. Epub 2018 Mar 2.

Department of Surgical Oncology and Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

Unprecedented advances in the treatment of cancer have occurred through the use of immunotherapy, with several agents currently approved by the Food and Drug Administration (FDA) for the treatment of widespread metastatic disease across cancer types. Immune checkpoint blockade represents a particularly promising class of agents that block inhibitory molecules on the surface of T cells, resulting in their activation and propagation of an immune response. Treatment with these agents may re-invigorate anti-tumor immunity, resulting in therapeutic responses, and use of these agents currently is being studied in the adjuvant setting. Additionally, a strong rationale exists for their use in the neoadjuvant setting for high-risk resectable disease (e.g., regional nodal disease in the case of melanoma). This rationale is based on the relatively high risk of relapse for these patients, as well as on scientific evidence suggesting that long-term immunologic memory and tumor control may be superior in the setting of treatment for an intact tumor (i.e., neoadjuvant therapy) as opposed to treatment in the setting of micrometastatic disease (e.g., adjuvant treatment). The potential advantages of this approach and the current landscape for neoadjuvant immune checkpoint blockade is discussed in this report, as well as caveats that should be considered by clinicians contemplating this strategy.
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http://dx.doi.org/10.1245/s10434-018-6379-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105272PMC
July 2018

Genomic and immune heterogeneity are associated with differential responses to therapy in melanoma.

NPJ Genom Med 2017 7;2. Epub 2017 Apr 7.

Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.

Appreciation for genomic and immune heterogeneity in cancer has grown though the relationship of these factors to treatment response has not been thoroughly elucidated. To better understand this, we studied a large cohort of melanoma patients treated with targeted therapy or immune checkpoint blockade ( = 60). Heterogeneity in therapeutic responses via radiologic assessment was observed in the majority of patients. Synchronous melanoma metastases were analyzed via deep genomic and immune profiling, and revealed substantial genomic and immune heterogeneity in all patients studied, with considerable diversity in T cell frequency, and few shared T cell clones (<8% on average) across the cohort. Variables related to treatment response were identified via these approaches and through novel radiomic assessment. These data yield insight into differential therapeutic responses to targeted therapy and immune checkpoint blockade in melanoma, and have key translational implications in the age of precision medicine.
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http://dx.doi.org/10.1038/s41525-017-0013-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5557036PMC
April 2017

Distinct Cellular Mechanisms Underlie Anti-CTLA-4 and Anti-PD-1 Checkpoint Blockade.

Cell 2017 Sep 10;170(6):1120-1133.e17. Epub 2017 Aug 10.

Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Parker Institute for Cancer Immunotherapy, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. Electronic address:

Immune-checkpoint blockade is able to achieve durable responses in a subset of patients; however, we lack a satisfying comprehension of the underlying mechanisms of anti-CTLA-4- and anti-PD-1-induced tumor rejection. To address these issues, we utilized mass cytometry to comprehensively profile the effects of checkpoint blockade on tumor immune infiltrates in human melanoma and murine tumor models. These analyses reveal a spectrum of tumor-infiltrating T cell populations that are highly similar between tumor models and indicate that checkpoint blockade targets only specific subsets of tumor-infiltrating T cell populations. Anti-PD-1 predominantly induces the expansion of specific tumor-infiltrating exhausted-like CD8 T cell subsets. In contrast, anti-CTLA-4 induces the expansion of an ICOS Th1-like CD4 effector population in addition to engaging specific subsets of exhausted-like CD8 T cells. Thus, our findings indicate that anti-CTLA-4 and anti-PD-1 checkpoint-blockade-induced immune responses are driven by distinct cellular mechanisms.
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http://dx.doi.org/10.1016/j.cell.2017.07.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5591072PMC
September 2017

Hallmarks of response to immune checkpoint blockade.

Br J Cancer 2017 Jun 18;117(1):1-7. Epub 2017 May 18.

Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.

Unprecedented advances have been made in the treatment of cancer through the use of immune checkpoint blockade, with approval of several checkpoint blockade regimens spanning multiple cancer types. However, responses to this form of therapy are not universal, and insights are clearly needed to identify optimal biomarkers of response and to combat mechanisms of therapeutic resistance. A working knowledge of the hallmarks of cancer yields insight into responses to immune checkpoint blockade, although the focus of this is rather tumour-centric and additional factors are pertinent, including host immunity and environmental influences. Herein, we describe the foundation for pillars and hallmarks of response to immune checkpoint blockade, with a discussion of their relevance to immune monitoring and mechanisms of resistance. Evolution of this understanding will ultimately help guide treatment strategies to enhance therapeutic responses.
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http://dx.doi.org/10.1038/bjc.2017.136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520201PMC
June 2017

Gene Targeting Meets Cell-Based Therapy: Raising the Tail, or Merely a Whimper?

Clin Cancer Res 2017 Jan 11;23(2):327-329. Epub 2016 Nov 11.

Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.

Appreciation of the immune effects of targeted agents has grown, and efforts to combine these agents with immunotherapy are underway to enhance therapeutic responses. Multiple ongoing trials are examining this concept; however, nuances exist with regard to timing, sequence, and combinatorial strategies. Clin Cancer Res; 23(2); 327-9. ©2016 AACRSee related article by Deniger et al., p. 351.
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http://dx.doi.org/10.1158/1078-0432.CCR-16-2493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5241203PMC
January 2017

Engineered CAR T Cells Targeting the Cancer-Associated Tn-Glycoform of the Membrane Mucin MUC1 Control Adenocarcinoma.

Immunity 2016 06;44(6):1444-54

Center for Cellular Immunotherapies, Abramson Cancer Center and the Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Department of Pathology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA. Electronic address:

Genetically modified T cells expressing chimeric antigen receptors (CARs) demonstrate robust responses against lineage restricted, non-essential targets in hematologic cancers. However, in solid tumors, the full potential of CAR T cell therapy is limited by the availability of cell surface antigens with sufficient cancer-specific expression. The majority of CAR targets have been normal self-antigens on dispensable hematopoietic tissues or overexpressed shared antigens. Here, we established that abnormal self-antigens can serve as targets for tumor rejection. We developed a CAR that recognized cancer-associated Tn glycoform of MUC1, a neoantigen expressed in a variety of cancers. Anti-Tn-MUC1 CAR T cells demonstrated target-specific cytotoxicity and successfully controlled tumor growth in xenograft models of T cell leukemia and pancreatic cancer. These findings demonstrate the therapeutic efficacy of CAR T cells directed against Tn-MUC1 and present aberrantly glycosylated antigens as a novel class of targets for tumor therapy with engineered T cells.
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http://dx.doi.org/10.1016/j.immuni.2016.05.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358667PMC
June 2016

Ibrutinib enhances chimeric antigen receptor T-cell engraftment and efficacy in leukemia.

Blood 2016 Mar 26;127(9):1117-27. Epub 2016 Jan 26.

Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA.

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is highly promising but requires robust T-cell expansion and engraftment. A T-cell defect in chronic lymphocytic leukemia (CLL) due to disease and/or therapy impairs ex vivo expansion and response to CAR T cells. To evaluate the effect of ibrutinib treatment on the T-cell compartment in CLL as it relates to CAR T-cell generation, we examined the phenotype and function of T cells in a cohort of CLL patients during their course of treatment with ibrutinib. We found that ≥5 cycles of ibrutinib therapy improved the expansion of CD19-directed CAR T cells (CTL019), in association with decreased expression of the immunosuppressive molecule programmed cell death 1 on T cells and of CD200 on B-CLL cells. In support of these findings, we observed that 3 CLL patients who had been treated with ibrutinib for ≥1 year at the time of T-cell collection had improved ex vivo and in vivo CTL019 expansion, which correlated positively together and with clinical response. Lastly, we show that ibrutinib exposure does not impair CAR T-cell function in vitro but does improve CAR T-cell engraftment, tumor clearance, and survival in human xenograft models of resistant acute lymphocytic leukemia and CLL when administered concurrently. Our collective findings indicate that ibrutinib enhances CAR T-cell function and suggest that clinical trials with combination therapy are warranted. Our studies demonstrate that improved T-cell function may also contribute to the efficacy of ibrutinib in CLL. These trials were registered at www.clinicaltrials.gov as #NCT01747486, #NCT01105247, and #NCT01217749.
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http://dx.doi.org/10.1182/blood-2015-11-679134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778162PMC
March 2016

Affinity-Tuned ErbB2 or EGFR Chimeric Antigen Receptor T Cells Exhibit an Increased Therapeutic Index against Tumors in Mice.

Cancer Res 2015 Sep;75(17):3596-607

Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania. Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.

Target-mediated toxicity is a major limitation in the development of chimeric antigen T-cell receptors (CAR) for adoptive cell therapy of solid tumors. In this study, we developed a strategy to adjust the affinities of the scFv component of CAR to discriminate tumors overexpressing the target from normal tissues that express it at physiologic levels. A CAR-expressing T-cell panel was generated with target antigen affinities varying over three orders of magnitude. High-affinity cells recognized target expressed at any level, including at levels in normal cells that were undetectable by flow cytometry. Affinity-tuned cells exhibited robust antitumor efficacy similar to high-affinity cells, but spared normal cells expressing physiologic target levels. The use of affinity-tuned scFvs offers a strategy to empower wider use of CAR T cells against validated targets widely overexpressed on solid tumors, including those considered undruggable by this approach.
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http://dx.doi.org/10.1158/0008-5472.CAN-15-0159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4560113PMC
September 2015

Rational development and characterization of humanized anti-EGFR variant III chimeric antigen receptor T cells for glioblastoma.

Sci Transl Med 2015 Feb;7(275):275ra22

Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.

Chimeric antigen receptors (CARs) are synthetic molecules designed to redirect T cells to specific antigens. CAR-modified T cells can mediate long-term durable remissions in B cell malignancies, but expanding this platform to solid tumors requires the discovery of surface targets with limited expression in normal tissues. The variant III mutation of the epidermal growth factor receptor (EGFRvIII) results from an in-frame deletion of a portion of the extracellular domain, creating a neoepitope. We chose a vector backbone encoding a second-generation CAR based on efficacy of a murine scFv-based CAR in a xenograft model of glioblastoma. Next, we generated a panel of humanized scFvs and tested their specificity and function as soluble proteins and in the form of CAR-transduced T cells; a low-affinity scFv was selected on the basis of its specificity for EGFRvIII over wild-type EGFR. The lead candidate scFv was tested in vitro for its ability to direct CAR-transduced T cells to specifically lyse, proliferate, and secrete cytokines in response to antigen-bearing targets. We further evaluated the specificity of the lead CAR candidate in vitro against EGFR-expressing keratinocytes and in vivo in a model of mice grafted with normal human skin. EGFRvIII-directed CAR T cells were also able to control tumor growth in xenogeneic subcutaneous and orthotopic models of human EGFRvIII(+) glioblastoma. On the basis of these results, we have designed a phase 1 clinical study of CAR T cells transduced with humanized scFv directed to EGFRvIII in patients with either residual or recurrent glioblastoma (NCT02209376).
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http://dx.doi.org/10.1126/scitranslmed.aaa4963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4467166PMC
February 2015

Potential role of 5-aza-2'-deoxycytidine induced MAGE-A4 expression in immunotherapy for anaplastic thyroid cancer.

Surgery 2013 Dec;154(6):1456-62; discussion 1462

Massachusetts General Hospital, Harvard Medical School, Boston, MA.

Background: Melanoma antigen gene family (MAGE)-A4, a member of the cancer testis antigen family, has been reported in various cancers including melanoma, bladder, head and neck, oral, and lung, and is a potential target for T-cell-receptor-based immunotherapy. Baseline expression levels of the MAGE-A4 gene in thyroid cancer cell lines have not been previously studied thoroughly.

Methods: Human thyroid cancer cell lines (8505c, HTh7, BCPAP, and TPC-1) were treated with either 10 μmol/L 5'-azacytidine (Aza) or 10 μmol/L 5-AZA-2'deoxycytidine (DAC) and evaluated for various MAGEA gene expression. Later melanoma cell lines A375 and 8505c were treated with PLX4720 in combination with DAC and evaluated for MAGE-A4 expression.

Results: Only BCPAP cells expressed moderate levels of MAGE-A3 and MAGE-A6 at baseline. Treatment with DAC/Aza induced the expression of MAGE-A4 and MAGE-A1 in 8505c cells. PLX4720 treatment did not affect MAGE-A4 expression in 8505c cells, but increased its expression in A375 cells. In contrast, addition of PLX4720 to DAC-treated 8505c cells decreased the previously induced MAGE-A4 expression by DAC in these cells. A similar decrease in MAGE-A4 expression by DAC was also seen in 8505cBRAF(-/-) cells. Although DAC treatment resulted in demethylation of the MAGE-A4 promoter in 2 CpG sites, PLX addition to DAC did not affect the demethylation status.

Conclusion: Demethylating agents increased the expression of MAGE genes in thyroid cancer cells. The effect of BRAFV600E inhibitors on MAGE-A4 expression suggest the role of downstream MEK/BRAF signaling in its expression apart from promoter demethylation being the sole requirement. Expression of MAGE-A4 may make immunotherapeutic intervention possible in selected patients with thyroid cancer.
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http://dx.doi.org/10.1016/j.surg.2013.07.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3863391PMC
December 2013

BRAF inhibition is associated with enhanced melanoma antigen expression and a more favorable tumor microenvironment in patients with metastatic melanoma.

Clin Cancer Res 2013 Mar 10;19(5):1225-31. Epub 2013 Jan 10.

Division of Surgical Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

Purpose: To evaluate the effects of BRAF inhibition on the tumor microenvironment in patients with metastatic melanoma.

Experimental Design: Thirty-five biopsies were collected from 16 patients with metastatic melanoma pretreatment (day 0) and at 10 to 14 days after initiation of treatment with either BRAF inhibitor alone (vemurafenib) or BRAF + MEK inhibition (dabrafenib + trametinib) and were also taken at time of progression. Biopsies were analyzed for melanoma antigens, T-cell markers, and immunomodulatory cytokines.

Results: Treatment with either BRAF inhibitor alone or BRAF + MEK inhibitor was associated with an increased expression of melanoma antigens and an increase in CD8+ T-cell infiltrate. This was also associated with a decrease in immunosuppressive cytokines [interleukin (IL)-6 and IL-8] and an increase in markers of T-cell cytotoxicity. Interestingly, expression of exhaustion markers TIM-3 and PD1 and the immunosuppressive ligand PDL1 was increased on treatment. A decrease in melanoma antigen expression and CD8 T-cell infiltrate was noted at time of progression on BRAF inhibitor alone and was reversed with combined BRAF and MEK inhibition.

Conclusions: Together, these data suggest that treatment with BRAF inhibition enhances melanoma antigen expression and facilitates T-cell cytotoxicity and a more favorable tumor microenvironment, providing support for potential synergy of BRAF-targeted therapy and immunotherapy. Interestingly, markers of T-cell exhaustion and the immunosuppressive ligand PDL1 are also increased with BRAF inhibition, further implying that immune checkpoint blockade may be critical in augmenting responses to BRAF-targeted therapy in patients with melanoma.
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http://dx.doi.org/10.1158/1078-0432.CCR-12-1630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3752683PMC
March 2013

Targeting the MAGE A3 antigen in pancreatic cancer.

Surgery 2012 Sep 6;152(3 Suppl 1):S13-8. Epub 2012 Jul 6.

Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA.

Pancreatic cancer is the fourth-leading cause of death in the United States and one of the most aggressive known malignancies. New and innovative advances in treatment are desperately needed. One promising area of investigational treatment for pancreatic cancer involves the use of immunotherapy. The development of immunotherapy for pancreatic cancer has been hampered by difficulty in generating tumor-reactive lymphocytes from resected specimens and by a lack of appropriate target antigens expressed on tumor cells. Innovative strategies have been developed with the use of peripheral blood lymphocytes that are genetically engineered to express T-cell receptors targeting common tumor antigens, including cancer-testis antigens, such as the MAGE-A3 antigen. Cancer-testis antigens pose excellent targets for immunotherapy because they are expressed in cancer and in the testis, an immune-privileged site, but have limited expression in normal tissue. An additional advantage in targeting cancer-testis antigens for immunotherapy is that their expression can be selectively up-regulated in tumor cells via epigenetic regulation with chromatin remodeling agents. Current interest in targeting cancer-testis antigens in pancreatic cancer is well-founded because cancer-testis antigens have been shown to be expressed in pancreatic cancer as potential targets for therapy. In our studies, we validated the expression pattern of cancer-testis antigens in resected specimens of pancreatic cancer and tested the hypothesis that treatment of pancreatic cancer cells with chromatin remodeling agents would render them more sensitive to antigen-specific T lymphocytes. We focused predominately on the MAGE-A3 antigen because it is highly expressed in pancreatic cancer, and several immunotherapeutic strategies are in clinical trials targeting this specific antigen. The results of these studies have important translational implications and provide the rationale for combined treatment with chromatin remodeling agents and immunotherapeutic approaches for pancreatic cancer.
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http://dx.doi.org/10.1016/j.surg.2012.05.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806055PMC
September 2012

EGFR-mediated re-activation of MAPK signaling contributes to insensitivity of BRAF mutant colorectal cancers to RAF inhibition with vemurafenib.

Cancer Discov 2012 Mar 16;2(3):227-35. Epub 2012 Jan 16.

Massachusetts General Hospital Cancer Center, Boston, MA 02129, USA.

Unlabelled: BRAF mutations occur in 10-15% of colorectal cancers (CRCs) and confer adverse outcome. While RAF inhibitors such as vemurafenib (PLX4032) have proven effective in BRAF mutant melanoma, they are surprisingly ineffective in BRAF mutant CRCs, and the reason for this disparity remains unclear. Compared to BRAF mutant melanoma cells, BRAF mutant CRC cells were less sensitive to vemurafenib, and P-ERK suppression was not sustained in response to treatment. Although transient inhibition of phospho-ERK by vemurafenib was observed in CRC, rapid ERK re-activation occurred through EGFR-mediated activation of RAS and CRAF. BRAF mutant CRCs expressed higher levels of phospho-EGFR than BRAF mutant melanomas, suggesting that CRCs are specifically poised for EGFR-mediated resistance. Combined RAF and EGFR inhibition blocked reactivation of MAPK signaling in BRAF mutant CRC cells and markedly improved efficacy in vitro and in vivo. These findings support evaluation of combined RAF and EGFR inhibition in BRAF mutant CRC patients.

Significance: BRAF valine 600 (V600) mutations occur in 10% to 15% of colorectal cancers, yet these tumors show a surprisingly low clinical response rate (~5%) to selective RAF inhibitors such as vemurafenib, which have produced dramatic response rates (60%–80%) in melanomas harboring the identical BRAF V600 mutation. We found that EGFR-mediated MAPK pathway reactivation leads to resistance to vemurafenib in BRAF-mutant colorectal cancers and that combined RAF and EGFR inhibition can lead to sustained MAPK pathway suppression and improved efficacy in vitro and in tumor xenografts.
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http://dx.doi.org/10.1158/2159-8290.CD-11-0341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308191PMC
March 2012

COT drives resistance to RAF inhibition through MAP kinase pathway reactivation.

Nature 2010 Dec 24;468(7326):968-72. Epub 2010 Nov 24.

Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, Massachusetts 02142, USA.

Oncogenic mutations in the serine/threonine kinase B-RAF (also known as BRAF) are found in 50-70% of malignant melanomas. Pre-clinical studies have demonstrated that the B-RAF(V600E) mutation predicts a dependency on the mitogen-activated protein kinase (MAPK) signalling cascade in melanoma-an observation that has been validated by the success of RAF and MEK inhibitors in clinical trials. However, clinical responses to targeted anticancer therapeutics are frequently confounded by de novo or acquired resistance. Identification of resistance mechanisms in a manner that elucidates alternative 'druggable' targets may inform effective long-term treatment strategies. Here we expressed ∼600 kinase and kinase-related open reading frames (ORFs) in parallel to interrogate resistance to a selective RAF kinase inhibitor. We identified MAP3K8 (the gene encoding COT/Tpl2) as a MAPK pathway agonist that drives resistance to RAF inhibition in B-RAF(V600E) cell lines. COT activates ERK primarily through MEK-dependent mechanisms that do not require RAF signalling. Moreover, COT expression is associated with de novo resistance in B-RAF(V600E) cultured cell lines and acquired resistance in melanoma cells and tissue obtained from relapsing patients following treatment with MEK or RAF inhibitors. We further identify combinatorial MAPK pathway inhibition or targeting of COT kinase activity as possible therapeutic strategies for reducing MAPK pathway activation in this setting. Together, these results provide new insights into resistance mechanisms involving the MAPK pathway and articulate an integrative approach through which high-throughput functional screens may inform the development of novel therapeutic strategies.
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http://dx.doi.org/10.1038/nature09627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3058384PMC
December 2010

Selective BRAFV600E inhibition enhances T-cell recognition of melanoma without affecting lymphocyte function.

Cancer Res 2010 Jul 15;70(13):5213-9. Epub 2010 Jun 15.

Division of Surgical Oncology, Medical Oncology, and Dermatology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

Targeted therapy against the BRAF/mitogen-activated protein kinase (MAPK) pathway is a promising new therapeutic approach for the treatment of melanoma. Treatment with selective BRAF inhibitors results in a high initial response rate but limited duration of response. To counter this, investigators propose combining this therapy with other targeted agents, addressing the issue of redundancy and signaling through different oncogenic pathways. An alternative approach is combining BRAF/MAPK-targeted agents with immunotherapy. Preliminary evidence suggests that oncogenic BRAF (BRAF(V600E)) contributes to immune escape and that blocking its activity via MAPK pathway inhibition leads to increased expression of melanocyte differentiation antigens (MDA). Recognition of MDAs is a critical component of the immunologic response to melanoma, and several forms of immunotherapy capitalize on this recognition. Among the various approaches to inhibiting BRAF/MAPK, broad MAPK pathway inhibition may have deleterious effects on T lymphocyte function. Here, we corroborate the role of oncogenic BRAF in immune evasion by melanoma cells through suppression of MDAs. We show that inhibition of the MAPK pathway with MAPK/extracellular signal-regulated kinase kinase (MEK) inhibitors or a specific inhibitor of BRAF(V600E) in melanoma cell lines and tumor digests results in increased levels of MDAs, which is associated with improved recognition by antigen-specific T lymphocytes. However, treatment with MEK inhibitors impairs T lymphocyte function, whereas T-cell function is preserved after treatment with a specific inhibitor of BRAF(V600E). These findings suggest that immune evasion of melanomas mediated by oncogenic BRAF may be reversed by targeted BRAF inhibition without compromising T-cell function. These findings have important implications for combined kinase-targeted therapy plus immunotherapy for melanoma.
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http://dx.doi.org/10.1158/0008-5472.CAN-10-0118DOI Listing
July 2010

Gene therapy with human and mouse T-cell receptors mediates cancer regression and targets normal tissues expressing cognate antigen.

Blood 2009 Jul 18;114(3):535-46. Epub 2009 May 18.

Surgery Branch, Hatfield Clinical Research Center, National Cancer Institute/NIH, Bethesda, MD 20892, USA.

Gene therapy of human cancer using genetically engineered lymphocytes is dependent on the identification of highly reactive T-cell receptors (TCRs) with antitumor activity. We immunized transgenic mice and also conducted high-throughput screening of human lymphocytes to generate TCRs highly reactive to melanoma/melanocyte antigens. Genes encoding these TCRs were engineered into retroviral vectors and used to transduce autologous peripheral lymphocytes administered to 36 patients with metastatic melanoma. Transduced patient lymphocytes were CD45RA(-) and CD45RO(+) after ex vivo expansion. After infusion, the persisting cells displayed a CD45RA(+) and CD45RO(-) phenotype. Gene-engineered cells persisted at high levels in the blood of all patients 1 month after treatment, responding patients with higher ex vivo antitumor reactivity than nonresponders. Objective cancer regressions were seen in 30% and 19% of patients who received the human or mouse TCR, respectively. However, patients exhibited destruction of normal melanocytes in the skin, eye, and ear, and sometimes required local steroid administration to treat uveitis and hearing loss. Thus, T cells expressing highly reactive TCRs mediate cancer regression in humans and target rare cognate-antigen-containing cells throughout the body, a finding with important implications for the gene therapy of cancer. This trial was registered at www.ClinicalTrials.gov as NCI-07-C-0174 and NCI-07-C-0175.
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http://dx.doi.org/10.1182/blood-2009-03-211714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929689PMC
July 2009