# IMPROVED CANCER IMAGING BY SECOND ANTIBODY

> **NIH NIH R01** · CTR FOR MOLECULAR MEDICINE/IMMUNOLOGY · 1989 · $253,741

## Abstract

We have shown that tumor imaging with a radiolabeled antibody (PA)
against carcinoembryonic antigen (CEA) can be improved by rapidly
removing excess PA from the blood with a second antibody (SA; 1,2).
Although useful for imaging, this anti-antibody method may have greater
utility for therapeutic applications.  Thus, the principal aim of this
project is to determine the efficacy of using a second antibody (SA) to
improve radioimmunotherapy (RAIT) of cancer.  Removal of nontumor
targeted, blood-pool radioantibody reduces the toxicity of RAIT
treatment by removing harmful amounts of radioactivity from the blood
and nontumor tissues, while maintaining a high retention of
radioantibody in the tumor.  We will examine the extent of RAIT
improvement using this SA method in nude mice bearing tumors
subcutaneously or in visceral organs (liver and lungs), or
intraperitoneally, to determine how tumors located in these various
sites are influenced by radioantibody treatment.  Comparisons will be
made to single and multiple injection of the radioantibody alone with or
without SA, with SA as intact IgG or F(ab') 2 fragments, and to F(ab') 2
fragments of radiolabeled PA.  Both I-131-and Y-90-Labeled PA will be
tested to compare the utility of the SA to reduce toxicity and improve
tumoricidal effects with PA labeled with iodine or a metal.  Additional
studies will assess the ability of the SA to reduce the immune response
against the PA by rapidly removing it from the blood.  In this case
mouse anti-goat IgG will be given to BALB/C mice at various times after
their injection with goat IgG.  Mouse anti-goat IgG will be used to
provide a SA that is not immunogenic.  Finally, we will evaluate the
efficacy and possible toxic-side effects of the SA method in rabbits
with a mouse monoclonal anti-CEA antibody and a baboon SA that could be
used in future clinical trials.  These studies will determine what role
the SA may have in improving RAIT in man.

## Key facts

- **NIH application ID:** 3175829
- **Project number:** 2R01CA037895-04
- **Recipient organization:** CTR FOR MOLECULAR MEDICINE/IMMUNOLOGY
- **Principal Investigator:** Robert M Sharkey
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1989
- **Award amount:** $253,741
- **Award type:** 2
- **Project period:** 1986-07-15 → 1993-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3175829

## Citation

> US National Institutes of Health, RePORTER application 3175829, IMPROVED CANCER IMAGING BY SECOND ANTIBODY (2R01CA037895-04). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3175829. Licensed CC0.

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