title: Chemical Screens Identify Drugs that Enhance or Mitigate Cellular Responses to Antibody-Toxin Fusion Proteins.
abstract: The intersection of small molecular weight drugs and antibody-based therapeutics is rarely studied in large scale. Both types of agents are currently part of the cancer armamentarium. However, very little is known about how to combine them in optimal ways. Immunotoxins are antibody-toxin gene fusion proteins engineered to target cancer cells via antibody binding to surface antigens. For fusion proteins derived from Pseudomonas exotoxin (PE), potency relies on the enzymatic domain of the toxin which catalyzes the ADP-ribosylation of EF2 causing inhibition of protein synthesis leading to cell death. Candidate immunotoxins have demonstrated clear value in clinical trials but generally have not been curative as single agents. Therefore we undertook three screens to discover effective combinations that could act synergistically. From the MIPE-3 library of compounds we identified various enhancers of immunotoxin action and at least one major class of inhibitor. Follow-up experiments confirmed the screening data and suggested that immunotoxins when administered with everolimus or nilotinib exhibit favorable combinatory activity and would be candidates for preclinical development. Mechanistic studies revealed that everolimus-immunotoxin combinations acted synergistically on elements of the protein synthetic machinery, including S61 kinase and 4E-BP1 of the mTORC1 pathway. Conversely, PARP inhibitors antagonized immunotoxins and also blocked the toxicity due to native ADP-ribosylating toxins. Thus, our goal of investigating a chemical library was justified based on the identification of several approved compounds that could be developed preclinically as 'enhancers' and at least one class of mitigator to be avoided.
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Antonella
authors.initials: A
authors.lastname: Antignani
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, United States of America.
authors.forename: Lesley
authors.initials: L
authors.lastname: Mathews Griner
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, United States of America.
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Guha
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Nathan
authors.initials: N
authors.lastname: Simon
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pasetto
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Keller
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Manjie
authors.initials: M
authors.lastname: Huang
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Evan
authors.initials: E
authors.lastname: Angelus
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: Ira
authors.initials: I
authors.lastname: Pastan
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, United States of America.
authors.forename: Marc
authors.initials: M
authors.lastname: Ferrer
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, United States of America.
authors.forename: David J
authors.initials: DJ
authors.lastname: FitzGerald
authors.affiliation: Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, United States of America.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Thomas
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D055808:Drug Discovery / Q000379:methods; D004354:Drug Screening Assays, Antitumor; D005098:Exotoxins / Q000235:genetics; D005260:Female; D006801:Humans; D000922:Immunotoxins / Q000235:genetics / Q000494:pharmacology; D051379:Mice; D000067856:Poly(ADP-ribose) Polymerase Inhibitors / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology*; D054852:Small Molecule Libraries; D014118:Toxins, Biological / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D005098:Exotoxins; D000922:Immunotoxins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011993:Recombinant Fusion Proteins; D054852:Small Molecule Libraries; D014118:Toxins, Biological