Cancer treatments can cause serious side effects which may last a lifetime because chemotherapy, which is a part of the cancer treatment, besides attacking tumors, attacks healthy cells as well. Immunotherapy, which stimulates the immune system to detect and attack cancer cells, is no exception either. Although these treatments help extend the lifespan of many cancer patients, they somehow do not provide a complete cure for the disease. However, these side effects can be mitigated if the therapy is designed to target only the cancer cells. Scientists around the world are working towards finding a safer cure for cancer. Meanwhile, researchers at the University of Chicago, US have discovered an innovative approach, that is to mask the cancer drug until it reaches the tumor.
A cure with a twist
The human body’s innate immune system responds to threats, guided by proteins called cytokines, which activate killer T-cells and can attack cancer cells. Scientists say that cytokines can be a wonderful tool in treating cancer as they can train the immune system to kill tumors. Though discovered 30 years ago, one such cytokine Interleukin (IL) 12, has not been approved by the FDA for cancer treatment as it was found to damage the liver.
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IL-12 indicates the immune cells produce a mass of inflammatory molecules that damage the body, causing severe side effects. Scientists have been researching for a long time whether IL-2 can be re-engineered to fight the cancer cells without damaging the healthy tissue and here is what they have found.
Masking for a safer version
There is a key difference between cancer cells and healthy cells. Cancer cells proliferate very rapidly. They produce certain enzymes that help them penetrate the surrounding healthy cells. This way, they quickly replicate and take over the entire body. Healthy cells, on the other hand, grow at a much slower pace and produce fewer of these enzymes. American scientists have relied on this key discrepancy to develop a safer version of IL-12.
Usually, a component of IL-12 protein binds itself to immune cells and activates them. Scientists have masked this receptor binding site with a cap. The cap gets removed only after it comes close to the tumor cells and detects the relevant enzymes. IL-12 proteins are activated during that phase and stimulate nearby T-cells to attack the tumor.
The masked IL-12 cytokines were experimented with in vitro on tumors and healthy tissues collected from breast cancer patients. It was identified that the tumor cells could remove the mask. When tested in rats, it was found that the masked IL-12 did not cause any damage to the animals’ livers. It was further observed that masked IL-12 proteins can trigger a strong immune response by targeting tumors without invading healthy organs.
Breast cancer models have shown that this treatment can cure up to 90 percent of cases while the commonly used immunotherapy called checkpoint inhibitor cures only 10 percent of cases. Masked IL-2 showed a 100 percent cure rate in colon cancer models. Scientists are gearing up for clinical trials where they study the efficacy of masked IL-2 in cancer patients.
