Scientific Accomplishments

> Tumor - Stroma Interactions
> Molecules and Pathways in the Tumor Microenvironment with Anti-tumor Activity
> Viral Infections and Malignancy
> Clinical Studies of Novel Immune- and Microenvironment-based Therapeutics

Theme 1: Tumor - Stroma Interactions

Dr. Zena Werb has been studying CSF-1, which is a major myeloid cell mitogen, and signaling through its receptor CSF-1R is also linked to poor outcomes. To characterize myeloid cell function in tumors, her group combined confocal intravital microscopy with depletion of CSF-1R-dependent cells using a neutralizing CSF-1R antibody in the MMTV-PyMT breast cancer mouse model. Anti-CSF-1R treatment altered stromal dynamics, and impaired both survival of myeloid dendritic cells (M-DCs) and accumulation of new M-DCs, but did not deplete Gr-1-positive neutrophils or block doxorubicin-induced myeloid cell recruitment, and had a minimal effect on lung myeloid cells. Nevertheless, prolonged treatment led to delayed tumor growth, reduced vascularity, and decreased lung metastasis (Lohela et al., Proc Nat Acad Sci USA, 2014). In a study in collaboration with Dr. Emmanuelle Passegue, the Werb group has shown that production of atypical T cell-suppressive neutrophils also occurs during early tumor progression at the onset of malignant conversion and that these cells preferentially accumulate in peripheral tissues. Production of these cells results from activation of a myeloid differentiation program in bone marrow (BM) by a novel mechanism in which tumor-derived G-CSF directs expansion and differentiation of hematopoietic stem cells to skew hematopoiesis toward the myeloid lineage (Casbon et al., Proc Nat Acad Sci USA, 2015).

Dr. Valerie Weaver has shown that stiffness also induces an epithelial-mesenchymal transition (EMT) in mammary tumors and they found that this is mediated through HIF1a, which is induced directly through extracellular matrix (ECM) tension and FAK activation, as well as by compromising the tumor vasculature to induce hypoxia (Mouw et al., Nat Med, 2014). They showed that tissue tension can promote breast malignancy by increasing levels of microRNA-18a, which then directly and indirectly via HoxA9 represses levels of the tumor suppressor PTEN. They demonstrated that elevated miR-18a and reduced HoxA9 and PTEN correlate with ECM stiffness in human breast tumors and can be used to distinguish luminal B from luminal A breast tumors. In a seminal article (Paszek et al., Nature, 2014), they revealed how the tumor associated increase in glycoproteins, which is particularly increased in metastatic tumors and circulating tumor cells, promotes anchorage-independent growth and survival in cells by increasing the bulkiness of the glycocalyx to activate and cluster integrins and increase receptor tyrosine kinase signaling.

Dr. Arthur Weiss, in collaboration with Dr. Kevan Shokat (Developmental Therapeutics, Cancer Genetics Programs), has developed a chemical-genetic system in the mouse that allows control of Src family kinases in a ligand-independent manner (Au-Yeung et al., Nature Immunology, 2014). Using similar chemical genetic tools for the ZAP-70 kinase, Weiss and Shokat studied the requirements for ZAP-70 during T cell development and for T cell proliferation (Au-Yeung et al., Nature Immunology, 2014), and they showed a discrete signaling threshold exists for the induction of T cell proliferation.


Theme 2: Molecules and Pathways in the Tumor Microenvironment with Anti-tumor Activity

Dr. Rosemary Akhurst has continued to work on mouse models of cancer, with a focus on the role played by the TGFβ signaling pathway in tumor progression and metastasis. In determining how the genetics of the host influence the response to down-regulation of TGFb signaling they have studied Tgfb1-/- mice and rare human families who have mutations in components of the TGFb signaling pathway, ENG or ACVRL1. They also demonstrated that polymorphic variants in mice of a disintegrin and metalloprotease 17 (Adam17) differentially regulate TGFβ signaling output and influence the severity of Tgfb1-dependent vascular pathology (Kawasaki et al., Proc Nat Acad Sci USA, 2014).

Dr. Mark Ansel made significant strides this year in his work to identify and characterize miRNAs that regulate T cell effector functions and the target mRNA networks through which they function. They completed work demonstrating that miR-19a, part of the miR-17~92 cluster (a.k.a. “oncomir-1”), is a powerful regulatory of allergic responses (Baumjohann et al., Nature immunology, 2013).

Dr. Jason Cyster has been studying germinal center (GC) B cell-like diffuse large B cell lymphoma (GCB-DLBCL). In work that was performed in collaboration with members of the Lymphoma and Leukemia Molecular Profiling Project (LLMPP), he identified 12 sphingosine-1-phosphate receptor-2 (S1PR2) mutations in 117 GCB-DLBCL cases and established that most disrupted the receptor’s migration and Akt inhibitory functions. GNA13 (encoding Gα13) is also frequently mutated in GCB-DLBCL and in Burkitt’s lymphoma (BL), and he has identified a Gα13-dependent regulatory pathway confining GC B cells that is frequently disrupted in lymphoma (Muppidi et al., Nature, 2014).

Dr. Averil Ma has continued to study A20, a potent anti-inflammatory protein that also functions as a tumor suppressor. A20 is a complex ubiquitin-modifying enzyme that possesses de-ubiquitinating and E3 ligase motifs (Tiruppathi et al., Nature Immunology, 2014). He has discovered a new role for A20 in regulating inflammasomes, since A20-deficient cells exhibit spontaneous inflammasome activation in response to LPS alone. This study revealed that IL-1b inflammasome complexes are ubiquitinated, and that spontaneous inflammasome activation requires RIP3.

Theme 3: Viral Infections and Malignancy

Dr. Joel Palefsky has showed that oral HPV prevalence is high among HIV-positive men who have sex with men, but concordant type-specific oral-anal HPV infection was rare. Increased risk of oral HPV infection was associated with oral-penile sex (Prendes et al., Head Neck, 2015). Given the high risk of anal cancer in this population, they initiated a large randomized controlled trial supported by the NCI to determine whether treatment of anal high-grade squamous intraepithelial lesions (HSIL) reduces the incidence of anal cancer.

Dr. Lanier has continued to study the response of Natural Killer cells to viral infection. He showed that the co-stimulatory molecule DNAM-1 is essential for optimal differentiation of memory natural killer cells during cytomegalovirus infection (Nabekura et al., Immunity, 2014), and that pro-apoptotic Bim regulates antigen-specific NK cell contraction and the generation of the NK cell memory pool following cytomegalovirus infection (Min-Oo et al., J Exp Med, 2014), Cytomegalovirus is a significant problem in cancer patients receiving hematopoietic stem cell transplantation in the treatment of leukemia.

Theme 4: Clinical Studies of Novel Immune- and Microenvironment-based Therapeutics

Dr. Fong has continued to assess the impact of cancer immunotherapy on tumor-specific responses in both animal models and in patients. They completed a trial where patients with localized prostate cancer receive neo-adjuvant sipuleucel-T and found that this treatment lead to a >3-fold increase in CD4+ T cells in the prostates of treated patients (Fong et al., J Natl Cancer Inst, 2014). These results demonstrate for the first time that sipuleucel-T treatment can modulate an immune response within the tumor microenvironment. They also have studied the effects of anti-CTLA-4 antibody (ipilimumab) treatment on the T cell repertoire using next generation sequencing to measure the diversity of T cell clonotypes in patients before and after treatment (Khan et al., J Exp Med, 2014). They found that anti-CTLA4 treatment can increase the clonotypic diversity in patients, expanding new T cell clones.(Cha et al., Science Trans Med, 2014)

Preclinical and Clinical Studies: Several Program members have been actively involved in evaluating different forms of therapy for cancer and pre-cancer, with an emphasis on novel immunotherapeutic strategies in both pre-clinical models and in human clinical trials.

Dr. Hideho Okada is developing novel and effective immunotherapy for brain cancer. He found that a toll-like receptor (TLR3) agonist poly-ICLC is an effective adjuvant for brain tumor immunotherapy (Pollack et al., J Clin Oncol, 2014). He has integrated these laboratory discoveries and conducted several novel immunotherapy trials in both adult and pediatric patients suffering from brain cancer (Johnson et al., Science Trans Med, 2015).

Dr. Lanier, in collaboration with Drs. Fong and Scott Oakes, has demonstrated tumor immune evasion by lactate dehydrogenase induction of NKG2D ligands on myeloid cells in cancer patients (Crane et al., Proc Nat Acad Sci USA, 2014)

Dr. James Rubenstein is developing novel therapies for primary central nervous system (CNS) lymphoma. Together with Drs. Pamela Munster (Developmental Therapeutics Program), Clifford Lowell, and Marc Shuman (Prostate Cancer Program), he is using preclinical models of CNS lymphoma, as well as multiple myeloma, to determine the role of tumor-associated macrophages in the pharmacologic response to rituximab (CNS lymphoma) (Kadoch et al., Clin Cancer Res, 2014)