Research in the Weissman Lab

Stem cell biology in health and disease and the development of macrophage-based immunotherapy:

Tissue stem cells are rare and only make the maturing and mature cells of the tissue they serve [HSC for blood, CNS stem cells for brain, skeletal stem cells for bone and cartilage and bone marrow inductive microenvironments, etc.]. Within a tissue they are the only cells that can self-renew throughout life. While the usual outcome is tissue and organ homeostasis, stem cells can accumulate and propagate mutations over many years, and those mutant stem cells can contribute to disease. Mutations that arise in any non-stem cell in a tissue are lost via the limited lifespan of non self-renewing cells. In leukemic cells, the lab discovered up-regulation of CD47 that acts as a ‘don’t eat me signal for macrophages and allows cancer cells to evade an immune response. They developed anti-CD47 as a cancer immunotherapy and continue to investigate how macrophages recognize and eliminate unhealthy cells, with a prospect of advancing medicine. 

The biology of HSC and their niche: Weissman was first to identify, prospectively isolate, and transplant hematopoietic [blood-forming] stem cells, called HSC from mice and humans. HSCs generate and regenerate the entire blood and immune systems throughout life. The lab has then isolated and studied the progenitor steps between the HSC and each of the blood cell type produced. He has also traced the formation of HSC during mouse embryogenesis and fetal development, and for all of these candidate stem and progenitor cells has optimized single cell RNAseq and utilized ATACseq and CHIPseq to elucidate the steady state expression of suites of genes that characterize each stem and progenitor cell in both species. These technologies have allowed the lab to propose candidate genes whose expression either characterize the molecular fingerprints of those cells, but point toward the events required for stem cell self-renewal and for differentiation to the next cell in the developmental pathways. To study HSC and their niche, the lab generated unique reporter mouse models in which HSC expressing a fluorescent marker, HoxB5.mCherry exist as single cells attached to a subtype of bone marrow blood vessel cell, surrounded also by stromal cells from the skeletal stem cell. In parabiotic pairs, mice with a joined vasculature to each other, these marked HSC migrate from one mouse to the partner bone marrow to occupy one of these vascular niches. Working out how these interactions and migrations occur and the molecules that are responsible is a current interest of the lab.

Human Brain Stem Cells [CNS SC]: Weissman and colleagues identified and prospectively isolated human fetal brain stem cells, and upon their transplantation into the brains of immune deficient mice, found that these CNS SC home to mouse brain stem cell niches near the lateral ventricles and in the dentate gyrus of the hippocampus. The progeny of these human CNS SC self-renew in these niches, migrate their progeny in a site appropriate manner long distances through the brain, and differentiate to neurons, astrocytes, and oligodendrocytes in site appropriate manners as well. This allows one to begin to understand adult human CNS SC behaviors. These human CNS SC can engraft in patients and have regenerative and neuroprotective properties. Each CNS SC can be propagated in vitro into clonal spheres of CNS SC. Recently students in the Weissman lab have found how to identify, isolate grow, and transplant human CNS SC from surgical samples. 

Stem Cells, Clonal Precancer Cells, and Progeny Cancer Stem Cells: Over the past 20 years the Weissman lab developed a method to identify mutations in single cells, and using that showed that preclinical progression occurs due to stepwise accumulation of driver mutations in a clone of HSCs leading to clonal expansions of preleukemic HSCs, competing with normal HSC for the single HSC cell niches, with the last step forming leukemia stem cells [LSC]. While random passenger mutations also occur, sometime creating new antigens; passenger mutations do not contribute to clonal expansions. The preleukemic HSC clones can become disease cells in CML, MDS, and acute leukemias. This model of preclinical cancer progression through accumulation of mutations in stem cells should apply to any somatic tissue. Work in the lab is currently focused on studying neural stem cells, their generation of oligolineage progenitors to form the brain neuropoietic tree similar to the hematopoietic  tree, to use them for study single cell RNAseq to discover genes enforcing or preventing each step of differentiation, and to identify genes that allow their progeny to self-renew, migrate, and differentiate in a site-appropriate manner. A current project in the lab is to isolate CNS-SC from surgical samples of brain tumors resected from patients with incurable brain cancers, to look for the order in which driver and passenger mutations occur, and to use their clonal expansion to neurospheres to work out the in vivo biological consequences of each driver mutation. 

Macrophage regulation and its therapeutic application: By comparing leukemic to healthy hematopietic stem cells, the Weissman lab has identified CD47 overexpression on LSC, and then on all cancers tested. They showed that CD47 is a cell surface molecule used by cancer cells to evade macrophage phagocytosis by binding to its receptor, SIRPa on macrophages. This led to the development of a new type of immunotherapy based on macrophage checkpoint inhibition through blockade of CD47 which is perhaps the first target  expressed on all human cancers tested. In pre-clinical research using patient-derived xenografts, we showed dramatic effects in the treatment of diverse types of human cancer with anti-CD47 antibodies or blocking agents that neutralize the inhibitory effect of CD47-SIRPa interaction and unleashes the ability of macrophages to engulf and eliminate cancer cells.  Importantly, antibody blockade of CD47 did not affect normal cells expressing CD47. This suggested that cancer cells but not normal cells display an ‘eat me’ signal, which they discovered to be calreticulin, a signal recognized by macrophage prophagocytic receptor CD91. Blockade of CD47 allows macrophage removal only of cells that express calreticulin on their surface. Weissman et al discovered that calreticulin is mainly produced and secreted by activated macrophages, and that it binds to nearby cancer cells through recognition of surface asialoglycans, presumably via sialic acid removing enzymes that create the calreticulin binding sites. The molecular and cellular mechanisms for this system are currently under study. The lab has also found 3 additional don’t eat me molecules and their macrophage receptors. 

Our findings in collaboration with the Leeper lab re Atherosclerosis: This collaboration has shown that atherosclerotic plaque formation involves the clonal expansion of arterial smooth muscle cells from local stem or progenitor cells. These cells display both CD47 and calreticulin on their surface. Treatment with anti-CD47 antibodies in a mouse model (high fat diet on a genetically susceptible background), resulted in the elimination of atherosclerotic lesions, and preliminary studies implicate this process in human atherosclerosis, a process that leads to heart attacks, stroke, aortic aneurysms, and loss of tissues in diabetic atherosclerosis. Current research in the lab continues to explore the role of macrophages in disease prevention and treatment, through understanding how macrophages recognize their target cells, and the signals that impact the ability of these cells to maintain tissue integrity and sustain a state of health. 


Stem cell research in a marine model organism: At the Hopkins Marine Station, the Weissman lab has space where it’s been conducting stem cell research in the marine model organism Botryllus schlosseri.  This model organism has very interesting stem cell biology and immunology as related above.. It is a colonial organism, in which each individual within the colony undergoes a complete regeneration cycle weekly through a process of budding. When two adjacent colonies develop vascular anastomoses, stem cells from one colony can compete with stem cells of the other; for the germline stem cells, there is always a winner and a loser strain. Practically what this means is that stem cells from one colony invade the other and can take over the germline so that the invaded colony will now produce gametes, reproductive cells, of the genotype of its neighbor.

The discovery of this process is what led Weissman to realize that stem cells can compete and to hypothesize and then prove that both spermatogenic stem cells compete in mice, and led to the concept and proof of competition in preleukemic clonal expansions, in the leukemias and in aging.  

A current list of publications

 

Director, Stanford Institute for Stem Cell Biology and Regenerative Medicine, Virginia & D.K. Ludwig Professor of Clinical Investigation in Cancer Research, Professor of Developmental Biology and, by courtesy, of Biology

Publications

  • Systemic and mucosal IgA responses are variably induced in response to SARS-CoV-2 mRNA vaccination and are associated with protection against subsequent infection. Mucosal immunology Sheikh-Mohamed, S., Isho, B., Chao, G. Y., Zuo, M., Cohen, C., Lustig, Y., Nahass, G. R., Salomon-Shulman, R. E., Blacker, G., Fazel-Zarandi, M., Rathod, B., Colwill, K., Jamal, A., Li, Z., de Launay, K. Q., Takaoka, A., Garnham-Takaoka, J., Patel, A., Fahim, C., Paterson, A., Li, A. X., Haq, N., Barati, S., Gilbert, L., Green, K., Mozafarihashjin, M., Samaan, P., Budylowski, P., Siqueira, W. L., Mubareka, S., Ostrowski, M., Rini, J. M., Rojas, O. L., Weissman, I. L., Tal, M. C., McGeer, A., Regev-Yochay, G., Straus, S., Gingras, A., Gommerman, J. L. 2022

    Abstract

    Although SARS-CoV-2 infects the upper respiratory tract, we know little about the amount, type, and kinetics of antibodies (Ab) generated in the oral cavity in response to COVID-19 vaccination. We collected serum and saliva samples from participants receiving two doses of mRNA COVID-19 vaccines and measured the level of anti-SARS-CoV-2 Ab. We detected anti-Spike and anti-Receptor Binding Domain (RBD) IgG and IgA, as well as anti-Spike/RBD associated secretory component in the saliva of most participants after dose 1. Administration of a second dose of mRNA boosted the IgG but not the IgA response, with only 30% of participants remaining positive for IgA at this timepoint. At 6 months post-dose 2, these participants exhibited diminished anti-Spike/RBD IgG levels, although secretory component-associated anti-Spike Ab were more stable. Examining two prospective cohorts we found that participants who experienced breakthrough infections with SARS-CoV-2 variants had lower levels of vaccine-induced serum anti-Spike/RBD IgA at 2-4 weeks post-dose 2 compared to participants who did not experience an infection, whereas IgG levels were comparable between groups. These data suggest that COVID-19 vaccines that elicit a durable IgA response may have utility in preventing infection.

    View details for DOI 10.1038/s41385-022-00511-0

    View details for PubMedID 35468942

  • 2021 Jeffrey M. Hoeg Award Lecture: Defining the Role of Efferocytosis in Cardiovascular Disease: A Focus on the CD47 (Cluster of Differentiation 47) Axis. Arteriosclerosis, thrombosis, and vascular biology Jarr, K., Kojima, Y., Weissman, I. L., Leeper, N. J. 2022: 101161ATVBAHA122317049

    Abstract

    A key feature of atherogenesis is the accumulation of diseased and dying cells within the lesional necrotic core. While the burden of intraplaque apoptotic cells may be driven in part by an increase in programmed cell death, mounting evidence suggests that their presence may primarily be dictated by a defect in programmed cell removal, or efferocytosis. In this brief review, we will summarize the evidence suggesting that inflammation-dependent changes within the plaque render target cells inedible and reduce the appetite of lesional phagocytes. We will present the genetic causation studies, which indicate these phenomena promote lesion expansion and plaque vulnerability, and the interventional data which suggest that these processes can be reversed. Particular emphasis is provided related to the antiphagocytic CD47 (cluster of differentiation 47) do not eat me axis, which has emerged as a novel antiatherosclerotic translational target that is predicted to provide benefit independent of traditional cardiovascular risk factors.

    View details for DOI 10.1161/ATVBAHA.122.317049

    View details for PubMedID 35387480

  • Molecular hallmarks of heterochronic parabiosis at single-cell resolution. Nature Palovics, R., Keller, A., Schaum, N., Tan, W., Fehlmann, T., Borja, M., Kern, F., Bonanno, L., Calcuttawala, K., Webber, J., McGeever, A., Tabula Muris Consortium, Luo, J., Pisco, A. O., Karkanias, J., Neff, N. F., Darmanis, S., Quake, S. R., Wyss-Coray, T., Almanzar, N., Antony, J., Baghel, A. S., Bakerman, I., Bansal, I., Barres, B. A., Beachy, P. A., Berdnik, D., Bilen, B., Brownfield, D., Cain, C., Chan, C. K., Chen, M. B., Clarke, M. F., Conley, S. D., Demers, A., Demir, K., de Morree, A., Divita, T., du Bois, H., Ebadi, H., Espinoza, F. H., Fish, M., Gan, Q., George, B. M., Gillich, A., Gomez-Sjoberg, R., Green, F., Genetiano, G., Gu, X., Gulati, G. S., Hahn, O., Haney, M. S., Hang, Y., Harris, L., He, M., Hosseinzadeh, S., Huang, A., Huang, K. C., Iram, T., Isobe, T., Ives, F., Jones, R. C., Kao, K. S., Karnam, G., Kershner, A. M., Khoury, N., Kim, S. K., Kiss, B. M., Kong, W., Krasnow, M. A., Kumar, M. E., Kuo, C. S., Lam, J., Lee, D. P., Lee, S. E., Lehallier, B., Leventhal, O., Li, G., Li, Q., Liu, L., Lo, A., Lu, W., Lugo-Fagundo, M. F., Manjunath, A., May, A. P., Maynard, A., McKay, M., McNerney, M. W., Merrill, B., Metzger, R. J., Mignardi, M., Min, D., Nabhan, A. N., Ng, K. M., Nguyen, P. K., Noh, J., Nusse, R., Patkar, R., Peng, W. C., Penland, L., Pollard, K., Puccinelli, R., Qi, Z., Rando, T. A., Rulifson, E. J., Segal, J. M., Sikandar, S. S., Sinha, R., Sit, R. V., Sonnenburg, J., Staehli, D., Szade, K., Tan, M., Tato, C., Tellez, K., Torrez Dulgeroff, L. B., Travaglini, K. J., Tropini, C., Tsui, M., Waldburger, L., Wang, B. M., van Weele, L. J., Weinberg, K., Weissman, I. L., Wosczyna, M. N., Wu, S. M., Xiang, J., Xue, S., Yamauchi, K. A., Yang, A. C., Yerra, L. P., Youngyunpipatkul, J., Yu, B., Zanini, F., Zardeneta, M. E., Zee, A., Zhao, C., Zhang, F., Zhang, H., Zhang, M. J., Zhou, L., Zou, J. 2022

    Abstract

    The ability to slow or reverse biological ageing would have major implications for mitigating disease risk and maintaining vitality1. Although an increasing number of interventions show promise for rejuvenation2, their effectiveness on disparate cell types across the body and the molecular pathways susceptible to rejuvenation remain largely unexplored. Here we performed single-cell RNA sequencing on 20 organs to reveal cell-type-specific responses to young and aged blood in heterochronic parabiosis. Adipose mesenchymal stromal cells, haematopoietic stem cells and hepatocytes are among those cell types that are especially responsive. On the pathway level, young blood invokes new gene sets in addition to reversing established ageing patterns, with the global rescue of genes encoding electron transport chain subunits pinpointing a prominent role of mitochondrial function in parabiosis-mediated rejuvenation. We observed an almost universal loss of gene expression with age that is largely mimicked by parabiosis: aged blood reduces global gene expression, and young blood restores it in select cell types. Together, these data lay the groundwork for a systemic understanding of the interplay between blood-borne factors and cellular integrity.

    View details for DOI 10.1038/s41586-022-04461-2

    View details for PubMedID 35236985

  • CD47 Blockade Leads to Chemokine-Dependent Monocyte Infiltration and Loss of B Cells from the Splenic Marginal Zone. Journal of immunology (Baltimore, Md. : 1950) Yiu, Y. Y., Hansen, P. S., Torrez Dulgeroff, L. B., Blacker, G., Myers, L., Galloway, S., Gars, E., Colace, O., Mansfield, P., Hasenkrug, K. J., Weissman, I. L., Tal, M. C. 2022

    Abstract

    CD47 is an important innate immune checkpoint through its interaction with its inhibitory receptor on macrophages, signal-regulatory protein alpha (SIRPalpha). Therapeutic blockade of CD47-SIRPalpha interactions is a promising immuno-oncology treatment that promotes clearance of cancer cells. However, CD47-SIRPalpha interactions also maintain homeostatic lymphocyte levels. In this study, we report that the mouse splenic marginal zone B cell population is dependent on intact CD47-SIRPalpha interactions and blockade of CD47 leads to the loss of these cells. This depletion is accompanied by elevated levels of monocyte-recruiting chemokines CCL2 and CCL7 and infiltration of CCR2+Ly6Chi monocytes into the mouse spleen. In the absence of CCR2 signaling, there is no infiltration and reduced marginal zone B cell depletion. These data suggest that CD47 blockade leads to clearance of splenic marginal zone B cells.

    View details for DOI 10.4049/jimmunol.2100352

    View details for PubMedID 35236754

  • PNP Hydrogel Prevents Formation of Symblephara in Mice After Ocular Alkali Injury. Translational vision science & technology Swarup, A., Grosskopf, A. K., Stapleton, L. M., Subramaniam, V. R., Li, B., Weissman, I. L., Appel, E. A., Wu, A. Y. 2022; 11 (2): 31

    Abstract

    Purpose: To create an alkali injury symblephara mouse model to study conjunctival fibrosis pathophysiology and test polymer nanoparticle (PNP) hydrogel as a preventative therapeutic.Methods: Mice were injured using NaOH-soaked filter paper to determine the optimal NaOH concentration to induce the formation of symblephara. Injured mice were observed for 7 days to detect the formation of symblephara. Forniceal shortening observed on hematoxylin and eosin (H&E)-stained tissue sections was used as a symblephara marker. Alpha-smooth muscle actin (alpha-SMA) expression, Masson's trichrome assay, and periodic acid-Schiff (PAS) staining were used to determine myofibroblast expression, collagen deposition, and goblet cell integrity. PNP hydrogel, with multivalent, noncovalent interactions between modified biopolymers and nanoparticles, was applied immediately after alkali injury to determine its ability to prevent the formation of symblephara.Results: Forniceal shortening was observed in H&E images with 1N NaOH for 2 minutes after 7 days without globe destruction. PNP hydrogel prevented forniceal shortening after alkali injury as observed by H&E histology. alpha-SMA expression and collagen deposition in eye tissue sections were increased in the fornix after injury with 1N NaOH compared with uninjured controls. PNP hydrogel treatment immediately after injury reduced alpha-SMA expression and collagen deposition in the forniceal region. Mucin-secreting goblet cells stained with PAS were significantly lower in alkali-injured and PNP hydrogel-treated conjunctivas than in uninjured control conjunctivas.Conclusions: We observed that 1N NaOH for 2 minutes induced maximal forniceal shortening and symblephara in mice. PNP hydrogel prevented forniceal shortening and conjunctival fibrosis after injury. This first murine model for symblephara will be useful to study fibrosis pathophysiology after conjunctival injury and to determine therapeutic targets for cicatrizing diseases.Translational Relevance: This mouse model of symblephara can be useful for studying conjunctival scarring disease pathophysiology and preventative therapeutics. We tested PNP hydrogel, which prevented the formation of symblephara after injury.

    View details for DOI 10.1167/tvst.11.2.31

    View details for PubMedID 35191963

  • CD47 expression attenuates Ebola virus-induced immunopathology in mice. Antiviral research Rao, D., O'Donnell, K. L., Carmody, A., Weissman, I. L., Hasenkrug, K. J., Marzi, A. 1800: 105226

    Abstract

    It has been shown that a very early cell-intrinsic response to infection is the upregulation of CD47 cell surface expression, a molecule known for delivering a "don't eat me signal" that inhibits macrophage-mediated phagocytosis and antigen presentation. Thus, blockade of CD47 signaling during lymphocytic choriomenigitis virus infections of mice has been shown to enhance the kinetics and potency of immune responses, thereby producing faster recovery. It seems counterintuitive that one of the earliest responses to infection would be immunoinhibitory, but it has been hypothesized that CD47 induction acts as an innate immune system checkpoint to prevent immune overactivation and immunopathogenic responses during certain infections. In the current study we examined the effect of CD47 blockade on lethal Ebola virus infection of mice. At 6 days post-infection, CD47 blockade was associated with significantly increased activation of B cells along with increases in recently cytolytic CD8+ T cells. However, the anti-CD47-treated mice exhibited increased weight loss, higher virus titers, and succumbed more rapidly. The anti-CD47-treated mice also had increased inflammatory cytokines in the plasma indicative of a "cytokine storm". Thus, in the context of this rapid hemorrhagic disease, CD47 blockade indeed exacerbated immunopathology and disease severity.

    View details for DOI 10.1016/j.antiviral.2021.105226

    View details for PubMedID 34923028

  • Coronary blood vessels from distinct origins converge to equivalent states during mouse and human development. eLife Phansalkar, R., Krieger, J., Zhao, M., Kolluru, S. S., Jones, R. C., Quake, S. R., Weissman, I., Bernstein, D., Winn, V. D., D'Amato, G., Red-Horse, K. 1800; 10

    Abstract

    Most cell fate trajectories during development follow a diverging, tree-like branching pattern, but the opposite can occur when distinct progenitors contribute to the same cell type. During this convergent differentiation, it is unknown if cells 'remember' their origins transcriptionally or whether this influences cell behavior. Most coronary blood vessels of the heart develop from two different progenitor sources-the endocardium (Endo) and sinus venosus (SV)-but whether transcriptional or functional differences related to origin are retained is unknown. We addressed this by combining lineage tracing with single-cell RNA sequencing (scRNAseq) in embryonic and adult mouse hearts. Shortly after coronary development begins, capillary endothelial cells (ECs) transcriptionally segregated into two states that retained progenitor-specific gene expression. Later in development, when the coronary vasculature is well established but still remodeling, capillary ECs again segregated into two populations, but transcriptional differences were primarily related to tissue localization rather than lineage. Specifically, ECs in the heart septum expressed genes indicative of increased local hypoxia and decreased blood flow. Adult capillary ECs were more homogeneous with respect to both lineage and location. In agreement, SV- and Endo-derived ECs in adult hearts displayed similar responses to injury. Finally, scRNAseq of developing human coronary vessels indicated that the human heart followed similar principles. Thus, over the course of development, transcriptional heterogeneity in coronary ECs is first influenced by lineage, then by location, until heterogeneity declines in the homeostatic adult heart. These results highlight the plasticity of ECs during development, and the validity of the mouse as a model for human coronary development.

    View details for DOI 10.7554/eLife.70246

    View details for PubMedID 34910626

  • Coronary blood vessels from distinct origins converge to equivalent states during mouse and human development ELIFE Phansalkar, R., Krieger, J., Zhao, M., Kolluru, S., Jones, R. C., Quake, S. R., Weissman, I., Bernstein, D., Winn, V. D., D'Amato, G., Red-Horse, K. 2021; 10
  • Inter-cellular CRISPR screens reveal regulators of cancer cell phagocytosis. Nature Kamber, R. A., Nishiga, Y., Morton, B., Banuelos, A. M., Barkal, A. A., Vences-Catalan, F., Gu, M., Fernandez, D., Seoane, J. A., Yao, D., Liu, K., Lin, S., Spees, K., Curtis, C., Jerby-Arnon, L., Weissman, I. L., Sage, J., Bassik, M. C. 2021

    Abstract

    Monoclonal antibody therapies targeting tumour antigens drive cancer cell elimination in large part by triggering macrophage phagocytosis of cancer cells1-7. However, cancer cells evade phagocytosis using mechanisms that are incompletely understood. Here we develop a platform for unbiased identification of factors that impede antibody-dependent cellular phagocytosis (ADCP) using complementary genome-wide CRISPR knockout and overexpression screens in both cancer cells and macrophages. In cancer cells, beyond known factors such as CD47, we identify many regulators of susceptibility to ADCP, including the poorly characterized enzyme adipocyte plasma membrane-associated protein (APMAP). We find that loss of APMAP synergizes with tumour antigen-targeting monoclonal antibodies and/or CD47-blocking monoclonal antibodies to drive markedly increased phagocytosis across a wide range of cancer cell types, including those that are otherwise resistant to ADCP. Additionally, we show that APMAP loss synergizes with several different tumour-targeting monoclonal antibodies to inhibit tumour growth in mice. Using genome-wide counterscreens in macrophages, we find that the G-protein-coupled receptor GPR84 mediates enhanced phagocytosis of APMAP-deficient cancer cells. This work reveals a cancer-intrinsic regulator of susceptibility to antibody-driven phagocytosis and, more broadly, expands our knowledge of the mechanisms governing cancer resistance to macrophage phagocytosis.

    View details for DOI 10.1038/s41586-021-03879-4

    View details for PubMedID 34497417

  • A Clinical PET Imaging Tracer ([18F]DASA-23) to Monitor Pyruvate Kinase M2 Induced Glycolytic Reprogramming in Glioblastoma. Clinical cancer research : an official journal of the American Association for Cancer Research Beinat, C., Patel, C. B., Haywood, T., Murty, S., Naya, L., Castillo, J. B., Reyes, S. T., Phillips, M., Buccino, P., Shen, B., Park, J. H., Koran, M. E., Alam, I. S., James, M. L., Holley, D., Halbert, K., Gandhi, H., He, J. Q., Granucci, M., Johnson, E., Liu, D. D., Uchida, N., Sinha, R., Chu, P., Born, D. E., Warnock, G. I., Weissman, I., Hayden Gephart, M., Khalighi, M. M., Massoud, T. F., Iagaru, A., Davidzon, G., Thomas, R., Nagpal, S., Recht, L. D., Gambhir, S. S. 2021

    Abstract

    PURPOSE: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain. We describe the development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. We evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients.EXPERIMENTAL DESIGN: [18F]DASA-23 was synthesized with a molar activity of 100.47 {plus minus} 29.58 GBq/mol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [18F]DASA-23 under FDA oversight, and evaluated it in healthy volunteers, and a pilot cohort of glioma patients.RESULTS: In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 {plus minus} 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [18F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it identified a metabolic non-responder within 1-week of treatment initiation.CONCLUSIONS: We developed and translated [18F]DASA-23 as a new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

    View details for DOI 10.1158/1078-0432.CCR-21-0544

    View details for PubMedID 34475101