Could A Common Bacteria Treat Cancer?

Researchers are studying an innovative type of immunotherapy that uses a common bacteria to treat cancer. The treatment, called LIME, short for Live Immune Modulating Engagers uses a safe form of E. coli to help the immune system better recognize and attack cancer.

In early research studies, LIME showed strong anti-tumor activity while limiting whole-body side effects. Here’s what that could mean for patients.

What is LIME immunotherapy?

LIME stands for Live Immune Modulating Engagers. It is a first-in-class type of cancer treatment being studied in clinical trials. This means it is the first of its kind.  It uses modified, non-harmful E. coli bacteria to activate immune cells directly inside tumors. 

Many current immune “engager” therapies circulate throughout the body. While they can be effective, they sometimes cause side effects like cytokine release syndrome (CRS), a strong inflammatory reaction. 

Regular immunotherapies may have a hard time entering the tumor microenvironment (TME). The TME is the protective environment around cancer cells that can weaken immune responses.

Researchers developed LIME to solve these challenges by delivering immune-activating signals directly inside the tumor.

How does LIME therapy work?

Researchers engineered a non-harmful, laboratory strain of E. coli. They made it  display special proteins on their surface called single-chain variable fragments (scFvs) .

These scFvs act like bridges. One side binds to cancer cells, and the other side binds to immune cells, such as:

• T cells, which are a key immune cell that kills infected or cancerous cells. T-LIME, was specially made for these cells, it activates them through CD3.
• Natural killer (NK) cells, which are immune cells that quickly attack abnormal cells. N-LIME was the target created for these cells which activates NK cells through NKG2D.

Which cancers were studied?

 LIME has been tested in laboratory and animal studies. The main focus was on cancers expressing certain proteins, including:

• CD19, commonly found in B-cell lymphomas
• Mesothelin (MSLN), often seen in pancreatic cancer and other solid tumors

The results in early studies showed tumor shrinkage and long-term survival

In mice with lymphoma, two intravenous (IV) doses of LIME combined with anti–PD-1 therapy (a type of immune checkpoint inhibitor) led to dramatic tumor shrinkage. Between 80% to 100% of mice survived long term, compared to poor outcomes in control groups.

LIME alone also showed activity, but worked especially well when combined with anti–PD-1 therapy. PD-1 inhibitors help “release the brakes” on immune cells, while LIME helps bring immune cells directly to the tumor and activate them.

And notably, the engineered bacteria concentrated up to 10 million times more inside tumors than in healthy organs. This suggests strong tumor targeting and limited exposure to the rest of the body.

Can LIME potentially reduce the risk of side effects?

One major concern with immune therapies is cytokine release syndrome (CRS), which can cause fever, low blood pressure, and inflammation.

In these studies, LIME triggered strong immune activity inside the tumor but caused only minimal increases in inflammatory cytokines in the bloodstream. This suggests that although LIME activates the immune system, it may not cause systemic toxicity.

However, it’s important to remember that these results are from early preclinical research. Human clinical trials are still needed.

Why is a precise tumor targeting so important?

To effectively eliminate cancer cells, the immune cells must physically reach cancer cells. This is why as a mechanism of self-preservation, cancer cells often hide inside a protective tumor microenvironment (TME). This environment can block immune cells from entering or weaken their activity. 

LIME appears to overcome this challenge in two ways:

1. The bacteria naturally accumulate in tumors.
2. They increase infiltration of T cells and NK cells into tumor tissue .

Imaging studies showed more immune cells entering tumors treated with LIME. 

What does this mean for patients with blood cancer?

For patients with B-cell lymphomas and other cancers, LIME represents a new direction in immunotherapy research. Instead of giving therapies that activate the immune system in general, this strategy delivers immune stimulation directly into the tumor.

That could mean:

• More precise targeting
• Better immune cell infiltration
• Fewer systemic side effects
• Stronger responses when combined with checkpoint inhibitors

While LIME is still in early-stage development, it highlights how cancer treatment continues to evolve. 

Next steps for LIME: making sure it is completely safe for human use

Before LIME can be used in patients, clinical trials are needed to confirm safety and effectiveness in humans. Researchers are continuing to refine the platform and explore additional cancer targets.

Stay tuned for more groundbreaking news on cancer therapies, approvals, clinical trials and become a part of our community, built by patients for patients.

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Source: LIME: A first-in-class of live bacterial immune engagers for cancer immunotherapy