# How Genentech Purifies Therapeutic Antibodies for Cancer Treatment

> A method for refining mixtures of anti-HER2 antibodies to ensure that harmful acidic variants remain below 25 percent of the total composition.

- **Patent:** US 6339142
- **Original title:** Protein purification
- **Owner:** Genentech Inc
- **Granted:** 2002
- **Status:** Public domain (expired)
- **Times cited:** 128
- **Field:** biotech, pharmaceutical

## What it does

This patent describes a process for purifying therapeutic proteins, specifically anti-HER2 antibodies, using ion exchange chromatography. The core mechanism involves adjusting the conductivity and pH levels of buffer solutions to separate the desired antibody from unwanted acidic variants. By carefully controlling these chemical conditions, the process ensures that the final mixture contains less than 25 percent of these acidic byproducts, which is critical for maintaining the safety and efficacy of the drug.

## What it does NOT cover

- Does not cover general protein purification methods that do not specifically target anti-HER2 antibodies.
- Does not cover purification techniques that rely solely on size-exclusion chromatography rather than ion exchange.
- Does not cover compositions where the acidic variant concentration exceeds the 25 percent threshold.

## The clever bit

The innovation lies in using precise conductivity and pH gradients to resolve subtle structural differences between a therapeutic antibody and its acidic variants, which are often nearly identical in size.

## Real-world examples

1. Herceptin (trastuzumab) manufacturing processes
2. Monoclonal antibody production lines
3. Biopharmaceutical quality control protocols

## Why it matters

This patent is foundational for the production of monoclonal antibody therapies like Herceptin. By establishing strict purity standards for these complex biological molecules, it helped define the manufacturing quality control processes now standard in the biopharmaceutical industry.

## Frequently asked questions

### What does How Genentech Purifies Therapeutic Antibodies for Cancer Treatment cover?

A method for refining mixtures of anti-HER2 antibodies to ensure that harmful acidic variants remain below 25 percent of the total composition.

### Who owns patent US 6339142?

Genentech Inc owns this patent, granted in 2002.

### 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 6339142 cited by?

This patent has been cited by 128 later patents that build on its ideas.

### What problem does this patent solve?

This patent is foundational for the production of monoclonal antibody therapies like Herceptin. By establishing strict purity standards for these complex biological molecules, it helped define the manufacturing quality control processes now standard in the biopharmaceutical industry.

### What does this patent NOT cover?

Does not cover general protein purification methods that do not specifically target anti-HER2 antibodies.

**Full plain-English explainer:** https://patentbrief.org/patent/us/6339142/rituxan-rituximab

**Original patent:** https://patents.google.com/patent/US6339142

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


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How Specific Antibody Drugs Are Stabilized for Storage and Use](https://patentbrief.org/patent/us/8372396/tysabri-natalizumab) — Genentech's 2013 patent details a precise recipe for an antibody drug, like Pertuzumab, using a special buffer, sugar, and cleaning agent to keep it stable for patients.
- [How to Redesign Mouse Antibodies for Safe Use in Humans](https://patentbrief.org/patent/us/6054297/rituxan-chop-chemotherapy) — Genentech's 1995 patent on a systematic method for humanizing rodent antibodies by grafting their disease-targeting loops onto a human consensus framework while carefully swapping key structural support residues to maintain binding strength.
- [Making High-Concentration Antibody Medicines Stable for Injection](https://patentbrief.org/patent/us/6267958/rituxan-chop) — Genentech's 2001 patent on a method to create stable, concentrated antibody medicines that can be easily reconstituted for injection, preventing degradation during freezing and storage.
- [How Genentech Created Antibodies to Stop Tumor Growth](https://patentbrief.org/patent/us/6884879/anti-vegf-antibodies) — A 1997 patent describing a specific humanized antibody designed to block VEGF, a protein that helps tumors grow their own blood supply.
- [How Genentech Created Antibodies to Target Prostate Cancer Cells](https://patentbrief.org/patent/us/6824780/avastin-dosing) — A patent describing specific antibodies that latch onto and kill cancer cells expressing the PSCA protein, effectively turning the body's immune-targeting tools into cancer-fighting weapons.