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  1. Science & Research (NCTR)

Barbara Parsons Ph.D.

Research Microbiologist — Division of Genetic and Molecular Toxicology

Barbara Parsons, Ph.D., Research Microbiologist


Barbara Parsons, Ph.D.
(870) 543-7121
NCTRResearch@fda.hhs.gov  

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About  |  Publications  |  Lab Members

Background

Barbara Parsons received a B.S. in biology from the State University of New York at Binghamton. She then worked as a technician for Nobel Laureate Richard Roberts at Cold Spring Harbor Laboratory where she participated in sequencing the Adenovirus 2 genome. As a participant in an interdisciplinary program in genetics, Dr. Parsons conducted research on Orthopoxvirus telomere structure and function and obtained a Ph.D. in microbiology and immunology from Duke University. She conducted post-doctoral research in plant molecular biology at the Beltsville Agricultural Research Center in Beltsville, MD, studying the plant hormone ethylene and its impact on tomato gene expression and fruit ripening. Dr. Parsons worked as a research associate at the University of Arkansas at Little Rock from before joining FDA’s National Center for Toxicological Research (NCTR) as an Oak Ridge Institute for Science and Education (ORISE) postdoctoral fellow in 1994. Dr. Parsons has been a principal investigator and a research microbiologist in the Division of Genetic and Molecular Toxicology at NCTR since 2002. Dr. Parsons has published 77 peer-reviewed journal articles, 77 abstracts, and 5 books, book chapters, or technical reports.

Dr. Parsons is recognized internationally for her work using measurements of cancer driver mutation (CDM) frequency to advance understanding of chemical carcinogenesis and cancer risk assessment. Her consulting and reviewing activities include:

  • Participating in the review of the International Agency for Research on Cancer’s Section on Mechanisms of Carcinogenesis
  • Planning a “State-of-the-Science Workshop on Chemically-induced Lung Tumors: Application to Human Health Risk Assessment” for the Environmental Protection Agency (EPA)
  • Serving as Editor of Mutation Research – Reviews in Mutation Research

She has served on National Cancer Institute grant review panels and a federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel reviewing “EPA’s Evaluation of the Carcinogenic Potential of Glyphosate.” Dr. Parsons has held leadership roles in scientific societies—most notably she held the elected offices of:

  • Councilor for the Society of Toxicology (SOT) Carcinogenesis Specialty Section
  • President of the South Central Chapter of SOT
  • Councilor of the Environmental Mutagenesis and Genomics Society (EMGS)
  • Secretary of EMGS

Dr. Parsons mentored seven postdoctoral fellows and a commissioner’s fellow. She received the Environmental Mutagenesis and Genomics Society Student Education Award in 2018. Her research has been recognized with numerous NCTR/FDA awards, including the FDA Scientific Achievement Award for Excellence in Laboratory Science for developing sensitive quantification of hotspot oncomutations by allele-specific competitive blocker polymerase chain reactions (ACB-PCR) in 2011. Within FDA, Dr. Parsons has represented NCTR on the FDA Biomarkers Working Group and participated in its planning of a public symposium on the “Identification of concepts & terminology for multi-component biomarkers.” She served as chair of NCTR’s Summer Student Research Program and NCTR’s Research Scientist Peer Review Committee.
 

Research Interests

Dr. Parsons has expertise in technologies for quantifying rare somatic mutation. She has used multiple methods to quantify somatic CDMs. These include standard sequencing, single-nucleotide primer extension, and droplet digital polymerase chain reaction (PCR), as well as technologies developed in her lab such as ACB-PCR, MutEx-ACB-PCR, and an error corrected next-generation sequencing (NGS) method called CarcSeq. While there are many useful tests for studying mutagenesis and genetic toxicology, the gold standard for carcinogenicity assessment is the rodent tumor bioassay, which is performed late in drug development programs because it is so resource intensive. A goal of Dr. Parsons’s research is to develop an early biomarker based on quantitation of somatic CDMs as a reporter of carcinogen-induced clonal expansion and future tumor development. Such a biomarker would be a useful new tool for carcinogenicity assessment. Incorporating such a biomarker into the repeat dose, preclinical studies performed early in drug development has the potential to increase drug development efficiency and support regulatory decision making.

Dr. Parsons has been a thought leader regarding how CDMs should be developed as biomarkers of cancer risk. She published several articles advocating for biologically realistic mathematical modeling of carcinogenesis, incorporating the ideas that most tumors are multiclonal in origin and reporting hotspot-containing cancer driver genes are enriched in functions related to cell:cell communication. She was early to recognized that CDMs are prevalent in normal human and rodent tissues, where they may serve as substrates and reporters of chemical carcinogenesis. Dr. Parsons characterized changes in CDM levels in response to treatment with mutagens and carcinogens (aristolochic acid, benzo[a]pyrene, ethylene oxide, furan, hexavalent chromium, naphthalene, and simulated solar light). Through ACB-PCR analysis of different CDMs (PIK3CA and TP53) in various normal human tissue samples (breast, colon, lung, and thyroid), Dr. Parsons’ group observed that the CDMs that show the greatest variation in mutant fraction level across individual tissue samples are the most potent tissue-specific drivers. Based on this observation, median absolute deviation (MAD) in tissue-specific drivers is being developed as a biomarker of clonal expansion and future cancer risk.
 

Professional Societies/National and International Groups

Environmental Mutagenesis and Genomics Society
Publication Policy Committee Member
2012 – Present

Annual Meeting Program Committee Member
2018 – 2020

Nominating Committe Member
2023 – 2024

Environmental and Molecular Mutagenesis
Editorial Board Member
2009 – Present

Health and Environmental Sciences Institue, Genetic Toxicology Technical Committee
Co-leader for the Error-corrected Next Generation Sequencing Group 
2021 – Present

Emerging Systems Toxicology for the Assessment of Risk (eSTAR) Error Corrected Sequencing Working Group Member
2022 – Present

International Conference on Environmental Mutagens 
Program Committee Member
2020 – 2022 

Symposium Chair
2022

International Workshops in Genetic Toxicology 
Sub-group Leader for Quantitative Analysis Work Group
2022 – 2024

Mutation Research – Reviewers in Mutation Research 
Editor
2019 – 2025

 

Select Publications

Publication titles are linked to text abstracts on PubMed.

CarcSeq Detection of Lorcaserin-Induced Clonal Expansion of Pik3ca H1047R Mutants in Rat Mammary Tissue.
Faske J.B., Myers M.B., Bryant M., He X., McLellen F., Bourcier F. and Parsons B.L.
Toxicol Sci. 2024, https://doi.org/10.1093/toxsci/kfae070.

Severity of Effect Considerations Regarding the Use of Mutation as a Toxicological Endpoint for Risk Assessment: A Report from the 8th International Workshop on Genotoxicity Testing (IWGT).
Parsons B.L., Beal M.A., Dearfield K.L., Douglas G.R., Gi M., Gollapudi B.B., Heflich R.H., Horibata K., Kenyon M., Long A.S., Lovell D.P., Lynch A.M., Myers M.B., Pfuhler S., Vespa A., Zeller A., Johnson G.E., and White P.A..
Environ Mol Mutagen. 2024, doi: 10.1002/em.22599.

Repeat Treatment of Organotypic Airway Cultures with Ethyl Methanesulfonate Causes Accumulation of Somatic Cell Mutations without Expansion of Bronchial-Carcinoma-Specific Cancer Driver Mutations.
Wang Y., Le Y., Harris K.L., Chen Y., Li X., Faske J., Wynne R.A., Mittelstaedt R.A., Cao X., Miranda-Colon J., Elkins L., Muskhelishvili L., Davis K., Mei N., Sun W., Robison T.W., Heflich R.H., and Parsons B.L.
Mutat Res Genet Toxicol Environ. Mutagen. 2024, 897:503786.

Error-Corrected Next Generation Sequencing - Promises and Challenges for Genotoxicity and Cancer Risk Assessment.
Marchetti F., Cardoso R., Chen C.L., Douglas G.R., Elloway J., Escobar P.A., Harper T. Jr., Heflich R.H., Kidd D., Lynch A.M., Myers M.B., Parsons B.L., Salk J.J., Settivari R.S., Smith-Roe S.L., Witt K.L., Yauk C.L., Young R., Zhang S., and Minocherhomji S.
Mutat Res Rev Mutat. Res. 2023, 792:108466.

Error-Corrected Next-Generation Sequencing to Advance Nonclinical Genotoxicity and Carcinogenicity Testing.
Marchetti F., Cardoso R., Chen C.L., Douglas G.R., Elloway J., Escobar P.A., Harper T. Jr., Heflich R.H., Kidd D., Lynch A.M., Myers M.B., Parsons B.L., Salk J.J., Settivari R.S., Smith-Roe S.L., Witt K.L., Yauk C., Young R.R., Zhang S., and Minocherhomji S.
Nat Rev Drug Discov. 2023, 22(3):165-166.

CarcSeq Measurement of Rat Mammary Cancer Driver Mutations and Relation to Spontaneous Mammary Neoplasia.
McKim K.L., Myers M.B., Harris K.L., Gong B., Xu J., and Parsons B.L.
Toxicol Sci. 2021, 182(1):142-158.

Assessment of Clonal Expansion Using CarcSeq Measurement of Lung Cancer Driver Mutations and Correlation with Mouse Strain- and Sex-Related Incidence of Spontaneous Lung Neoplasia.
Harris K.L., McKim K.L., Myers M.B., Gong B., Xu J., and Parsons B.L.
Toxicol Sci. 2021, 184(1):1-14.

Cross-Oncopanel Study Reveals High Sensitivity and Accuracy with Overall Analytical Performance Depending on Genomic Regions.
Gong B., Li D., Kusko R., Novoradovskaya N., Zhang Y., Wang S., Pabón-Peña C., Zhang Z., Lai K., Cai W., LoCoco J.S., Lader E., Richmond T.A., Mittal V.K., Liu L.C., Johann D.J. Jr, Willey J.C., Bushel P.R., Yu Y., Xu C., Chen G., Burgess D., Cawley S., Giorda K., Haseley N., Qiu F., Wilkins K., Arib H., Attwooll C., Babson K., Bao L., Bao W., Lucas A.B., Best H., Bhandari A., Bisgin H., Blackburn J., Blomquist T.M., Boardman L., Burgher B., Butler D.J., Chang C.J., Chaubey A., Chen T., Chierici M., Chin C.R., Close D., Conroy J., Cooley Coleman J., Craig D.J., Crawford E., Del Pozo A., Deveson I.W., Duncan D., Eterovic A.K., Fan X., Foox J., Furlanello C., Ghosal A., Glenn S., Guan M., Haag C., Hang X., Happe S., Hennigan B., Hipp J., Hong H., Horvath K., Hu J., Hung .LY., Jarosz M., Kerkhof J., Kipp B., Kreil D.P., Łabaj P., Lapunzina P., Li P., Li Q.Z., Li W., Li Z., Liang Y., Liu S., Liu Z., Ma C., Marella N., Martín-Arenas R., Megherbi D.B., Meng Q., Mieczkowski P.A., Morrison T., Muzny D., Ning B., Parsons B.L., Paweletz C.P., Pirooznia M., Qu W., Raymond A., Rindler P., Ringler R., Sadikovic B., Scherer A., Schulze E., Sebra R., Shaknovich R., Shi Q., Shi T., Silla-Castro J.C., Smith M., López M.S., Song P., Stetson D., Strahl M., Stuart A., Supplee J., Szankasi P., Tan H., Tang L.Y., Tao Y., Thakkar S., Thierry-Mieg D., Thierry-Mieg J., Thodima V.J., Thomas D., Tichý B., Tom N., Vallespin Garcia E., Verma S., Walker K., Wang C., Wang J., Wang Y., Wen Z., Wirta V., Wu L., Xiao C., Xiao C., Xu S., Yang M., Ying J., Yip S.H., Zhang G., Zhang S., Zhao M., Zheng Y., Zhou X., Mason C.E., Mercer T., Tong W., Shi L., Jones W., and Xu J.
Genome Biol. 2021, 22(1):109.

Rationale and Roadmap for Developing Panels of Hotspot Cancer Driver Gene Mutations as Biomarkers of Cancer Risk.
Harris K.L., Myers M.B., McKim K.L., Elespuru R.K., and Parsons B.L.
Environ Mol Mutagen. 2020, 61(1):152-175.

Outgrowth of Erlotinib-Resistant Subpopulations Recapitulated in Patient-Derived Lung Tumor Spheroids and Organoids.
Banda M., McKim K.L., Myers M.B., Inoue M., and Parsons B.L.
PLoS One. 2020, 15(9):e0238862.

ACB-PCR Quantification of Low-Frequency Hotspot Cancer-Driver Mutations.
Myers M.B., McKim K.L., Wang Y., Banda M., and Parsons B.L.
Environ Mol Mutagen. 2020, 61(1):152-175.

Multiclonal Tumor Origin: Evidence and implications.
Parsons B.L. 
Mutat Res Rev Mutat. Res. 2018, 777:1-18.

Variation in Organ‐Specific PIK3CA and KRAS Mutant Levels in Normal Human Tissues Correlates with Mutation Prevalence in Corresponding Carcinomas.
Parsons B., McKim K., and Myers M.
Environ Mol Mutagen. 2017, 58(7):466-476.

ACB-PCR Measurement of H-Ras Codon 61 CAA→CTA Mutation Provides an Early Indication of Aristolochic Acid I Carcinogenic Effect in Tumor Target Tissues.
Wang Y., Arlt V., Roufosse C., McKim K., Myers M., Phillips D., and Parsons B.
Environ Mol Mutagen. 2012, 53(7):495-504.

Oncomutations as Biomarkers of Cancer Risk.
Parsons B., Myers M., Meng F., Wang Y., and McKinzie P.
Environ Mol Mutagen. 2010, 51(8-9):836-50.

ACB-PCR Quantification of K-RAS Codon 12 GAT and GTT Mutant Fraction in Colon Tumor and Non-Tumor Tissue.
Parsons B., Marchant-Miros K., Delongchamp R., Verkler T., Patterson T., McKinzie P., and Kim L.
Cancer Invest. 2010, 28(4):364-75.

Many Different Tumor Types have Polyclonal Tumor Origin: Evidence and Implications.
Parsons B.L.
Mutat Res. 2008, 659(3):232-47.

Genotypic Selection Methods for the Direct Analysis of Point Mutations.
Parsons B.L. and Heflich R.H.
Mutat Res Rev Mutat Res. 1997, 387: 97-121.

Nucleotide Sequences from the Adenovirus-2 Genome.
Gingeras T.R., Sciaky D., Gelinas R.E., Bing-Dong J., Yen C.E., Kelly M.M., Bullock P.A., Parsons B.L., O’Neill K.E., and Roberts R.J.
J Biol Chem. 1982, 257:13475-13491

 

Lab Members

Contact information for all lab members:
(870) 543-7121
NCTRResearch@fda.hhs.gov  

Jennifer Faske, M.S.
Biology
 

Contact Information
Barbara Parsons
(870) 543-7121
Expertise
Expertise
Approach
Domain
Technology & Discipline
Toxicology
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