‘Masked’ Cancer Drug Sneaks Through Body

Many cancer treatments are notoriously savage on the body; they attack healthy cells at the same time as tumor cells, causing a plethora of side effects. Now, researchers at the University of Chicago’s Pritzker School of Molecular Engineering (PME) have designed a method to keep one promising cancer drug from wreaking such havoc. The team has engineered a new “masked” version of the immunotherapy drug interleukin-12 that is activated only when it reaches a tumor.

Researchers have long suspected that interleukin-12 could be a powerful cancer treatment, but it caused dangerous side effects. Now, Pritzker Molecular Engineering researchers have developed a version of the molecule not activated until it reaches a tumor, where it eradicates cancer cells.

Our research shows that this masked version of IL-12 is much safer for the body, but it possesses the same anti-tumor efficacy as the original,” said Aslan Mansurov, a postdoctoral research fellow and first author of the new paper. He carried out the IL-12 engineering work with Jeffrey Hubbell, the Eugene Bell Professor in Tissue Engineering, who co-leads PME’s Immunoengineering research theme with professor Melody Swartz.

Researchers know that IL-12 potently activates lymphocytes, immune cells with the potential to destroy tumor cells. But, in the 1990s, early clinical trials of IL-12 were halted because of severe, toxic side effects in patients. The same immune activation that started a cascade of events killing cancer cells also led to severe inflammation throughout the body. IL-12, at least in its natural form, was shelved.
The research on the molecule, also known as IL-12, is described in the journal Nature Biomedical Engineering.

But Mansurov, Hubbell, Swartz, and colleagues had an idea to reinvigorate the possibility of IL-12. What if the drug could slip through the body without activating the immune system? They designed a “masked molecule with a cap covering the section of IL-12 which normally binds immune cells. The cap can be removed only by tumor-associated proteases, a set of molecular scissors found in the vicinity of tumors to help them degrade surrounding healthy tissue. When the proteases chop off the cap, the IL-12 becomes active, able to spur an immune response against the tumor.

The masked IL-12 is largely inactive everywhere in the body except at the site of the tumor, where these proteases can cleave off the mask,” explained Mansurov.

Source: https://pme.uchicago.edu/