A Stable Recipe for a Cancer-Fighting Antibody Drug

This patent describes a specific, stable recipe for a cancer-fighting antibody-drug conjugate (ADC) that targets CD33, using cyclodextrin and a lyoprotectant to keep it effective and reduce impurities.

What it covers

The patent describes a specific pharmaceutical mixture, or "formulation," for a type of cancer drug called a benzodiazepine antibody-drug conjugate (ADC). This formulation aims to keep the ADC stable and minimize unwanted byproducts. It includes a specific monoclonal antibody, h2H16ec, designed to target human CD33, with an average of two drug molecules attached to engineered cysteine residues (Claim 1(a)). The formulation strictly limits a benzodiazepine-related impurity to no more than 0.1 μM (Claim 1(b)). To achieve stability, it uses 6% w/v hydroxypropyl-β-cyclodextrin (Claim 1(c)), 6% w/v sucrose as a lyoprotectant (Claim 1(d)), and a 20 mM KPhos buffer at pH 7.3 as a diluent (Claim 1(e)). For example, this precise mixture could be prepared and then freeze-dried for storage, ensuring the drug remains potent until it's ready for patient use.

What it doesn't cover

• —Does not cover ADC formulations that do not include a cyclodextrin, such as hydroxypropyl-β-cyclodextrin.
• —Does not cover formulations where the specific benzodiazepine-related impurity exceeds 0.1 μM.
• —Does not cover ADCs where the antibody does not specifically target human CD33, or is not h2H16ec with engineered cysteine residues.
• —Does not cover formulations using different lyoprotectants or diluents outside of 6% w/v sucrose and 20 mM KPhos buffer at pH 7.3.
• —Does not cover methods of making the ADC itself, only its final formulation.

The clever bit

The novelty lies in identifying a very specific combination of excipients—hydroxypropyl-β-cyclodextrin, sucrose, and KPhos buffer—that together stabilize a particular benzodiazepine ADC and keep a specific impurity below a critical threshold. This precise "recipe" solves the challenge of maintaining the drug's integrity and potency.

Why it matters

Antibody-drug conjugates are powerful cancer treatments, but they are complex molecules that can be unstable or degrade over time. This patent addresses a critical challenge in drug development: creating a stable, pharmaceutically acceptable formulation for a specific ADC. Ensuring stability and purity is essential for drug safety, efficacy, and shelf-life, which directly impacts patient access and treatment reliability. Seattle Genetics (now Seagen) is a leader in ADC technology, and this patent contributes to the practical application and commercial viability of such therapies.

Real-world examples

• 1.ADC therapies for cancer treatment
• 2.Lyophilized (freeze-dried) pharmaceutical products
• 3.Formulations for biologics
• 4.Seattle Genetics (Seagen) ADC pipeline