# Using Radioactive Antibodies to Treat B-Cell Lymphoma

> A method for treating B-cell lymphoma by using radioactive antibodies to target cancer cells without destroying the patient's bone marrow.

- **Patent:** US 5595721
- **Original title:** Radioimmunotherapy of lymphoma using anti-CD20
- **Owner:** Coulter Pharmaceutical Inc
- **Granted:** 1997
- **Status:** Public domain (expired)
- **Times cited:** 232
- **Field:** biotech, pharmaceutical

## What it does

This patent describes a three-step process to treat B-cell lymphoma using antibodies that target the CD20 protein on cancer cells. First, a small amount of radioactive antibody is injected to image the patient and see where the drug goes. Second, a dose of unlabeled antibody is given to block non-tumor binding sites, ensuring the radioactive dose hits the cancer rather than healthy tissue. Finally, a therapeutic dose of radioactive antibody is administered at a level high enough to kill cancer cells but low enough to avoid damaging the bone marrow, which eliminates the need for a stem cell transplant.

## What it does NOT cover

- Does not cover treatments that require hematopoietic stem cell replacement.
- Does not cover antibodies that do not target the CD20 antigen.
- Does not cover non-radioactive immunotherapy methods.
- Does not cover the manufacturing process of the antibodies themselves.

## The clever bit

The innovation is the pre-treatment step using unlabeled antibodies to saturate non-specific binding sites, which allows for a more precise and safer delivery of the radioactive payload to the tumor.

## Real-world examples

1. Bexxar (tositumomab and iodine I-131 tositumomab)

## Why it matters

This patent provided the foundation for Bexxar, a landmark radioimmunotherapy drug. By allowing for effective treatment without the harsh side effects of bone marrow destruction, it changed how doctors approached non-Hodgkin's lymphoma, moving toward more targeted, less toxic therapies.

## Frequently asked questions

### What does Using Radioactive Antibodies to Treat B-Cell Lymphoma cover?

A method for treating B-cell lymphoma by using radioactive antibodies to target cancer cells without destroying the patient's bone marrow.

### Who owns patent US 5595721?

Coulter Pharmaceutical Inc owns this patent, granted in 1997.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 5595721 cited by?

This patent has been cited by 232 later patents that build on its ideas.

### What problem does this patent solve?

This patent provided the foundation for Bexxar, a landmark radioimmunotherapy drug. By allowing for effective treatment without the harsh side effects of bone marrow destruction, it changed how doctors approached non-Hodgkin's lymphoma, moving toward more targeted, less toxic therapies.

### What does this patent NOT cover?

Does not cover treatments that require hematopoietic stem cell replacement.

**Full plain-English explainer:** https://patentbrief.org/patent/us/5595721/pcr-thermal-cycler

**Original patent:** https://patents.google.com/patent/US5595721

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._