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Michael S. Hwang

Bio: Michael S. Hwang is an academic researcher from Johns Hopkins University School of Medicine. The author has contributed to research in topics: Antigen & Mutant. The author has an hindex of 6, co-authored 12 publications receiving 156 citations. Previous affiliations of Michael S. Hwang include Johns Hopkins University & Howard Hughes Medical Institute.

Papers
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Journal ArticleDOI
05 Mar 2021-Science
TL;DR: In this paper, the authors describe the identification of an antibody highly specific to the most common TP53 mutation (R175H, in which arginine at position 175 is replaced with histidine) in complex with a common human leukocyte antigen-A (HLA-A) allele on the cell surface.
Abstract: TP53 (tumor protein p53) is the most commonly mutated cancer driver gene, but drugs that target mutant tumor suppressor genes, such as TP53, are not yet available. Here, we describe the identification of an antibody highly specific to the most common TP53 mutation (R175H, in which arginine at position 175 is replaced with histidine) in complex with a common human leukocyte antigen–A (HLA-A) allele on the cell surface. We describe the structural basis of this specificity and its conversion into an immunotherapeutic agent: a bispecific single-chain diabody. Despite the extremely low p53 peptide-HLA complex density on the cancer cell surface, the bispecific antibody effectively activated T cells to lyse cancer cells that presented the neoantigen in vitro and in mice. This approach could in theory be used to target cancers containing mutations that are difficult to target in conventional ways.

146 citations

Journal ArticleDOI
TL;DR: In this article, single-chain variable fragments (scFvs) were used to identify peptides derived from recurrent RAS mutations, G12V and Q61H/L/R, in the context of two common human leukocyte antigen (HLA) alleles.
Abstract: Mutations in the RAS oncogenes occur in multiple cancers, and ways to target these mutations has been the subject of intense research for decades. Most of these efforts are focused on conventional small-molecule drugs rather than antibody-based therapies because the RAS proteins are intracellular. Peptides derived from recurrent RAS mutations, G12V and Q61H/L/R, are presented on cancer cells in the context of two common human leukocyte antigen (HLA) alleles, HLA-A3 and HLA-A1, respectively. Using phage display, we isolated single-chain variable fragments (scFvs) specific for each of these mutant peptide-HLA complexes. The scFvs did not recognize the peptides derived from the wild-type form of RAS proteins or other related peptides. We then sought to develop an immunotherapeutic agent that was capable of killing cells presenting very low levels of these RAS-derived peptide-HLA complexes. Among many variations of bispecific antibodies tested, one particular format, the single-chain diabody (scDb), exhibited superior reactivity to cells expressing low levels of neoantigens. We converted the scFvs to this scDb format and demonstrated that they were capable of inducing T cell activation and killing of target cancer cells expressing endogenous levels of the mutant RAS proteins and cognate HLA alleles. CRISPR-mediated alterations of the HLA and RAS genes provided strong genetic evidence for the specificity of the scDbs. Thus, this approach could be applied to other common oncogenic mutations that are difficult to target by conventional means, allowing for more specific anticancer therapeutics.

83 citations

Journal ArticleDOI
01 May 2021
TL;DR: The opportunities and challenges involved in the identification of suitable public neoantigen targets and the development of therapeutic agents targeting them are reviewed.
Abstract: Several current immunotherapy approaches target private neoantigens derived from mutations that are unique to individual patients’ tumors. However, immunotherapeutic agents can also be developed against public neoantigens derived from recurrent mutations in cancer driver genes. The latter approaches target proteins that are indispensable for tumor growth, and each therapeutic agent can be applied to numerous patients. Here we review the opportunities and challenges involved in the identification of suitable public neoantigen targets and the development of therapeutic agents targeting them. Zhou and colleagues discuss the opportunities and challenges in targeting public neoantigens for cancer immunotherapy.

53 citations

Journal ArticleDOI
TL;DR: An approach to identify single-chain variable fragments specific for mutant peptides presented on the cell surface by HLA molecules and demonstrates that these scFvs can be successfully converted to full-length antibodies, termed MANAbodies, targeting “Mutation-Associated Neo-Antigens” bound to HLA.
Abstract: Mutant epitopes encoded by cancer genes are virtually always located in the interior of cells, making them invisible to conventional antibodies. We here describe an approach to identify single-chain variable fragments (scFvs) specific for mutant peptides presented on the cell surface by HLA molecules. We demonstrate that these scFvs can be successfully converted to full-length antibodies, termed MANAbodies, targeting "Mutation-Associated Neo-Antigens" bound to HLA. A phage display library representing a highly diverse array of single-chain variable fragment sequences was first designed and constructed. A competitive selection protocol was then used to identify clones specific for mutant peptides bound to predefined HLA types. In this way, we obtained two scFvs, one specific for a peptide encoded by a common KRAS mutant and the other by a common epidermal growth factor receptor (EGFR) mutant. The scFvs bound to these peptides only when the peptides were complexed with HLA-A2 (KRAS peptide) or HLA-A3 (EGFR peptide). We converted one scFv to a full-length antibody (MANAbody) and demonstrate that the MANAbody specifically reacts with mutant peptide-HLA complex even when the peptide differs by only one amino acid from the normal, WT form.

41 citations

Journal ArticleDOI
TL;DR: In this article, a proof-of-concept approach utilizing engineered T cells approximating NOT-gate Boolean logic to target counterexpressed antigens resulting from clonal loss of heterozygosity (LOH) events in cancer was proposed.
Abstract: Developing therapeutic agents with potent antitumor activity that spare normal tissues remains a significant challenge. Clonal loss of heterozygosity (LOH) is a widespread and irreversible genetic alteration that is exquisitely specific to cancer cells. We hypothesized that LOH events can be therapeutically targeted by "inverting" the loss of an allele in cancer cells into an activating signal. Here we describe a proof-of-concept approach utilizing engineered T cells approximating NOT-gate Boolean logic to target counterexpressed antigens resulting from LOH events in cancer. The NOT gate comprises a chimeric antigen receptor (CAR) targeting the allele of human leukocyte antigen (HLA) that is retained in the cancer cells and an inhibitory CAR (iCAR) targeting the HLA allele that is lost in the cancer cells. We demonstrate that engineered T cells incorporating such NOT-gate logic can be activated in a genetically predictable manner in vitro and in mice to kill relevant cancer cells. This therapeutic approach, termed NASCAR (Neoplasm-targeting Allele-Sensing CAR), could, in theory, be extended to LOH of other polymorphic genes that result in altered cell surface antigens in cancers.

27 citations


Cited by
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12 Jan 1987
TL;DR: In this paper, a monoclonal antibody against determinants of the HLA-A,B,C glycoproteins and pjmicroglobulin was developed.
Abstract: III Antibodies A Monoclonal antibodies against determinants of the HLA-A,-B,-C glycoproteins and pjmicroglobulin 1. Antibodies against species specific, non-polymorphic determinants 2. Antibodies against polymorphic HLA-A,-B,-C determinants B Monoclonal antibodies against HLA-DRw determinants 1. Antibody against a species specific HLA-DRw determinants 2. Antibodies against polymorphic HLA-DRw determinants

632 citations

Journal ArticleDOI
TL;DR: Novel immunotherapy strategies currently under investigation to confer antigen specificity, enhance T cell effector function, and neutralize immunosuppressive elements within the tumor microenvironment that may be rationally combined to untangle the web of immune resistance in PDA and other tumors are reviewed.

201 citations

Journal ArticleDOI
TL;DR: It is highlighted that irradiation of the DLN restrains adaptive immune responses through altered chemokine expression and CD8+ T-cell trafficking and has implications for combining radiotherapy and ICB, long-term survival, and induction of immunologic memory.
Abstract: Purpose: In the proper context, radiotherapy can promote antitumor immunity. It is unknown if elective nodal irradiation (ENI), a strategy that irradiates tumor-associated draining lymph nodes (DLN), affects adaptive immune responses and combinatorial efficacy of radiotherapy with immune checkpoint blockade (ICB).Experimental Design: We developed a preclinical model to compare stereotactic radiotherapy (Tumor RT) with or without ENI to examine immunologic differences between radiotherapy techniques that spare or irradiate the DLN.Results: Tumor RT was associated with upregulation of an intratumoral T-cell chemoattractant chemokine signature (CXCR3, CCR5-related) that resulted in robust infiltration of antigen-specific CD8+ effector T cells as well as FoxP3+ regulatory T cells (Tregs). The addition of ENI attenuated chemokine expression, restrained immune infiltration, and adversely affected survival when combined with ICB, especially with anti-CLTA4 therapy. The combination of stereotactic radiotherapy and ICB led to long-term survival in a subset of mice and was associated with favorable CD8 effector-to-Treg ratios and increased intratumoral density of antigen-specific CD8+ T cells. Although radiotherapy technique (Tumor RT vs. ENI) affected initial tumor control and survival, the ability to reject tumor upon rechallenge was partially dependent upon the mechanism of action of ICB; as radiotherapy/anti-CTLA4 was superior to radiotherapy/anti-PD-1.Conclusions: Our results highlight that irradiation of the DLN restrains adaptive immune responses through altered chemokine expression and CD8+ T-cell trafficking. These data have implications for combining radiotherapy and ICB, long-term survival, and induction of immunologic memory. Clinically, the immunomodulatory effect of the radiotherapy strategy should be considered when combining stereotactic radiotherapy with immunotherapy. Clin Cancer Res; 24(20); 5058-71. ©2018 AACR.

190 citations

Journal ArticleDOI
05 Mar 2021-Science
TL;DR: In this paper, the authors describe the identification of an antibody highly specific to the most common TP53 mutation (R175H, in which arginine at position 175 is replaced with histidine) in complex with a common human leukocyte antigen-A (HLA-A) allele on the cell surface.
Abstract: TP53 (tumor protein p53) is the most commonly mutated cancer driver gene, but drugs that target mutant tumor suppressor genes, such as TP53, are not yet available. Here, we describe the identification of an antibody highly specific to the most common TP53 mutation (R175H, in which arginine at position 175 is replaced with histidine) in complex with a common human leukocyte antigen–A (HLA-A) allele on the cell surface. We describe the structural basis of this specificity and its conversion into an immunotherapeutic agent: a bispecific single-chain diabody. Despite the extremely low p53 peptide-HLA complex density on the cancer cell surface, the bispecific antibody effectively activated T cells to lyse cancer cells that presented the neoantigen in vitro and in mice. This approach could in theory be used to target cancers containing mutations that are difficult to target in conventional ways.

146 citations

Journal ArticleDOI
TL;DR: The p53 pathway is a complex cellular stress response network with multiple diverse inputs and downstream outputs relevant to its role as a tumor suppressor pathway as mentioned in this paper, and the role of mutant p53 as a prognostic factor is recognized, the therapeutic modulation of its wild-type or mutant activities remain a work-in-progress.

107 citations