Ron S Gejman

Appointments

Fellow, Hematology/Oncology, Columbia University / New York Presbyterian Hospital, 2023-current
Postdoctoral Clinical Fellow, Columbia University Medical Center, 2023-current
Resident, Internal Medicine, Brigham and Women's Hospital, 2020-2023
Clinical Fellow in Medicine, Harvard Medical School, 2020-2023

Education

MD, Weill Cornell/Rockefeller/Sloan-Kettering MD/PhD Program, 2020
PhD, Weill Cornell/Rockefeller/Sloan-Kettering MD/PhD Program, 2018
B.A., Columbia University, 2010

I use in silico, in vitro and in vivo approaches to ask fundamental questions about cancer biology. My doctoral work was motivated by trying to understand how self/non-self discrimination occurs in the context of a tumor. I developed a novel approach to link MHC-I neoantigen expression to cellular barcodes called “PresentER” (Gejman eLife 2018; Gejman, Ca. Imm. Res. 2020). “PresentER” allows the creation of libraries of tens of thousands of precisely defined neoantigens to study TCR-reactivity and immunogenicity. Using PresentER libraries, we discovered that clonally expressed neoantigens could elicit strong immune responses in immunocompetent mice that eliminated tumors, while neoantigens with low clonality or in competition with other neoantigens could not. This may explain the clinically important inverse relationship between degree of intratumoral heterogeneity and response to immunotherapy in patients with cancer. We have also used this system to study the target-specificity of T cell receptor-based therapeutics and unexpectedly revealed extensive off-targets for some therapeutic agent classes. The tools I developed are now being used by dozens of laboratories. All PresentER vectors are available on AddGene.

Selected Publications

Heather F Jones, Zita EH Aretz, Ron S. Gejman, Tara Cicic, David A Scheinberg. "CD8 co-receptor modulates the specificity profile of the 1G4 TCR against NY-ESO-1." Molecular Therapy 2025. [Link]
Zachary H Walsh, Chris J Frangieh, Neeharika Kothapalli, Jay Levy, Clarissa K Heck, Johannes C Melms, Ron S. Gejman, Parin Shah, Jared M Pollard, Akul Naik, Sarah L Grauman, Lei Haley Huang, Ashley Lee, Dusan Bogunovic, Joshua D Milner, Benjamin Izar. "Scalable generation and functional classification of genetic variants in inborn errors of immunity to accelerate clinical diagnosis and treatment." Cell 2025. [Link]
Boaz Elad, Wojciech Rzechorzek, Kelly Axsom, Justin Fried, Farhana Latif, Adil Yunis, Carolyn Hennecken, Rubin Salazar, Kyung T Oh, David L Diuguid, Andrew H Lipsky, Ron S. Gejman, Gabriel Sayer, Nir Uriel, Dor Lotan. "Case Report: A Unique Case of Hemophagocytic Lymphohistiocytosis in Heart Transplant." Transplantation Proceedings 2025. 57(3):481-484. [Link]
Ron S. Gejman, Benjamin Izar. "Polyguanine microsatellites are robust replication clocks in cancer." Nature Genetics (News & Views) 2025. [Link]
Martin G.Klatt, Zita E.H.Aretz, Michael Curcio, Ron S. Gejman, Heather F. Jones, David A.Scheinberg. "An input-controlled model system for identification of MHC bound peptides enabling laboratory comparisons of immunopeptidome experiments." Journal of Proteomics 2020. DOI: 10.1016/j.jprot.2020.103921 [Link]
Ron S Gejman, Heather F Jones, Martin G Klatt, Aaron Y Chang, Claire Y Oh, Smita S. Chandran, Tatyana Korontsvit, Viktoriya Zakahleva, Tao Dao, Christopher A. Klebanoff and David A Scheinberg "Identification of the targets of T cell receptor therapeutic agents and cells by use of a high throughput genetic platform." Cancer Immunology Research 2020. DOI: 10.1158/2326-6066.CIR-19-0745 [Link]
Ron S. Gejman*, Aaron Y. Chang*, Heather F. Jones, Krysta DiKun, A. Ari Hakimi, Andrea Schietinger, David A. Scheinberg. "Rejection of immunogenic tumor clones is limited by clonal fraction." eLife 2018. DOI: 10.7554/eLife.41090 [Link] [eLife Insight]
Aaron Y. Chang, Tao Dao, Ron S. Gejman, Casey A. Jarvis, Andrew Scott, Leonid Dubrovsky, Melissa D. Mathias, Tatyana Korontsvit, Victoriya Zakhaleva, Michael Curcio, Ronald C. Hendrickson, Cheng Liu, and David A. Scheinberg. "A therapeutic T cell receptor mimic antibody targets tumor-associated PRAME peptide/HLA-I antigens." JCI. DOI: 10.1172/JCI92335 [Link]
Yasin Şenbabaoğlu*, Ron S. Gejman*, Andrew G. Winer, Ming Liu, Eliezer M. Van Allen, Guillermo de Velasco, Diana Miao, Irina Ostrovnaya, Esther Drill, Augustin Luna, Nils Weinhold, William Lee, Brandon J. Manley, Danny N. Khalil, Samuel D. Kaffenberger, Yingbei Chen, Ludmila Danilova, Martin H. Voss, Jonathan A. Coleman, Paul Russo, Victor E. Reuter, Timothy A. Chan, Emily H. Cheng, David A. Scheinberg, Ming O. Li, Toni K. Choueiri, James J. Hsieh, Chris Sander and A. Ari Hakimi. "Tumor immune microenvironment characterization in clear cell renal cell carcinoma identifies prognostic and immunotherapeutically relevant messenger RNA signatures." Genome Biology 2016. DOI: 10.1186/s13059-016-1092-z [Link]
Elliott J Brea, Claire Y Oh, Eusebio Manchado, Sadna Budhu, Ron S Gejman, George Mo, Patrizia Mondello, James E Han, Casey A Jarvis, David Ulmert, Qing Xiang, Aaron Y Chang, Ralph J Garippa, Taha Merghoub, Jedd D Wolchok, Neal Rosen, Scott W. Lowe and David A Scheinberg. "Kinase regulation of Human MHC Class I Molecule Expression on Cancer Cells.". Cancer Immunol Res 2016. DOI: 10.1158/2326-6066.CIR-16-0177 [Link].

Complete Publication List

Reviews

Aaron Y Chang, Ron S Gejman, Elliott J Brea, Claire Y Oh, Melissa Mathias, Dmitry Pankov, Emily Casey, Tao Dao & David A Scheinberg "Opportunities and challenges for TCR mimic antibodies in cancer therapy." Expert Opinion on Biological Therapy 2016. [Link]
Leonid Dubrovsky, Tao Dao, Ron S Gejman, Elliott Brea, Aaron Chang, Claire Oh, Emily Casey, Dmitry Pankov & David A. Scheinberg. "T cell receptor mimic antibodies for cancer therapy." Oncoimmunology 2015. [Link]

Invited Talks

The Ability of T Cell Antigens to Cause Tumor Cell Rejection Is Dependent on Tumor Cell Subclone Frequency. Keystone Precision Medicine in Cancer. Stockholm, Sweden. 2018.
Identification of Cross-reactive Targets of TCR-Based Therapeutic Agents Within the Human Proteome. Vincent du Vigneaud Memorial Research Symposium. New York, NY. 2018.

Awards and Recognition