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Ira Pastan, M.D.

Ira Pastan, M.D.

  • Center for Cancer Research
  • National Cancer Institute
NIH Distinguished Investigator
Head, Molecular Biology Section

RESEARCH SUMMARY

Dr. Pastan’s contributions to medical research include:

  • The discovery with R. Perlman of a new gene regulatory mechanism whereby many quiescent genes are activated by cyclic AMP and its DNA-binding partner CRP.
  • Receptor studies which provided the first evidence that peptide hormones bind to receptors on the surface cells, and the use of fluorescence methods to visualize the binding and internalization of insulin and other ligands by living cells, to measure their diffusion rates on the membrane before clustering and internalization, and to demonstrate that different ligands, including viruses, enter cells together in the same vesicles.
  • Research on the EGF receptor, which showed that the EGF-R (onco)gene is amplified and over-expressed in many human cancers, the cloning and sequencing of the EGF-R cDNA and with Doug Lowy, the demonstration that over-expression of EGF-R in the presence of EGF can transform normal cells into cancer cells.  These studies provided essential evidence that antibodies able to inactivate the EGF receptor could be useful in treating many cancers.
  • Studies with M. Gottesman on the biochemical basis of multi-drug resistance in cancer therapy, which involved the isolation of the first human multi-drug resistance gene (MDR1) gene and the demonstration that MDR1 encodes a multi-drug transporter that is highly expressed in many human cancers.
  • The development of recombinant immunotoxins for the treatment of cancer.Working with R. Kreitman and D. FitzGerald, I used protein engineering to produce novel chimeric proteins composed of an Fv that targets a protein on the surface of a cancer cell and a portion of a powerful protein toxin.  One of these Lumoxiti has been approved by the FDA for the treatment of leukemia.
  • The discovery of mesothelin (with M.C. Willingham) and the demonstration that it is an excellent target for antibody-based cancer therapies, because of its high expression on many cancers and lack of expression on essential normal organs.

Areas of Expertise

Protein and Antibody Engineering
Immunotoxins
Mesothelin
Immunogenicity

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Research

Mesothelin as a Target for Cancer Therapy by CAR-T cells and Bispecific Antibodies

To improve the therapy of cancer new approaches and drugs with unique mechanisms of action are needed. Mesothelin is a popular target on solid tumors. It was discovered by Ira Pastan and Mark Willingham in LMB, NCI. It is a lineage restricted cell surface protein that is highly expressed by many cancers, and only a few non-essential tissues. The specificity of mesothelin expression makes it a popular target for antibody-based therapies, but shed mesothelin has been found to be a major barrier to these therapies. To overcome the shedding problem, Pastan and collaborators developed Mab 15B6 that binds to a juxta-membrane region of mesothelin and does not bind to shed mesothelin. Mab 15B6 was used to make CAR T cells and bispecific (T cell engagers that have high anti-tumor activity in mice. An improved CAR-T cell variant is being prepared for clinical trials in human with mesothelin expressing cancers.

Image
Pastan Lab, 2023

Publications

Selected Key Publications

Mesothelin Immunotherapy for Cancer: Ready for Prime Time?

Hassan R., Thomas, A., Alewine, C., Le, D.T., Jaffee, E.M., and Pastan, I.
JOURNAL OF CLINICAL ONCOLOGY. 34: 4171, 2016.
Full-Text Article
[ Journal Article ]

Multiple proteases are involved in mesothelin shedding by cancer cells.

Liu, X., Chan, A., Tai, C.H., Andresson, T., Pastan, I.
Commun Biol.. 3(1): 728, 2020.
Full-Text Article
[ Journal Article ]

Highly active CAR T cells that bind to a juxtamembrane region of mesothelin and are not blocked by shed mesothelin

Liu X., Onda M., Watson N., Hassan R., Ho M., Bera T.K., Wei J., Chakraborty A., Beers R., Zhou Q., Shajahan A., Azadi P., Zhan J., Xia D., Pastan I.
PNAS. 119(19): e2202439119, 2022.
Full-Text Article
[ Journal Article ]

Tumor resistance to anti-mesothelin CAR-T cells caused by binding to shed mesothelin is overcome by targeting a juxtamembrane epitope

Liu X., Onda M., Schlomer J., Bassel L., Kozlov S., Tai C.H., Zhou Q., Liu W., Tsao H.-E., Hassan R., Ho M., Pastan I.
Full-Text Article
[ Journal Article ]

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Team

Lab Manager
Emily J. Danoff, Ph.D.
Biologist
Xiu-Fen Liu, Ph.D.
Biologist (Contr)
Qi Zhou
Postbaccalaureate Fellow
Eber Guzman-Cruz

News

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Covers

Oncotarget Cover - May 2016

Oncotarget 24 May 2016 issue cover

Published Date

Structural models of Recombinant Immunotoxins.

A. SS1P consists of the disulfide-stabilized heavy chain Fv (VH) (magenta) and light chain Fv (VL) (Cyan) of the antibody SS1P. The VH is linked to a 38-kDa fragment of PE38 that is divided into domain II (gray), domain III (yellow), and part of domain Ib from native PE38. B. SS1-LO10R. 24-kDa fragment of PE24 with six point mutations in domain III designed to eliminate binding to B-cell receptor. Point mutations are marked with red balls. C. LMB-T20. PE24 with six point mutations in domain III designed to diminish T-cell epitopes. D. LMB-T14. PE24 with 10 point mutations in domain III designed to diminish B and T cell epitopes. All models are hypothetical arrangements based on the structures of native PE and immunoglobulin G; they do not represent actual structure determinations. 

Citation

Dual B- and T-cell de-immunization of recombinant immunotoxin targeting mesothelin with high cytotoxic activity

Ronit Mazor1, Masanori Onda1, Dong Park1,3, Selamawit Addissie1, Laiman Xiang1,*, Jingli Zhang2, Raffit Hassan2 and Ira Pastan1

1 Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

2 Thoracic and GI Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

3 New Business Development Department, Medytox Inc., Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea

Oncotarget, Vol. 7, No. 21