Turbocharging the Killing Power of Immune Cells Against Cancer

Red blood cells floating through a vein.

The vaccines used by Pfizer and Moderna use small lipid nanoparticles to send a strand of genetic material into the cells and that is known as messenger RNA (mRNA). (Image: via Pixabay)

Creating “super soldiers” of specific immune cells to boost an anti-tumor response against cancer has been shown in a series of elegant experiments by researchers at Princess Margaret Cancer Centre.

Research led by Ph.D. candidate Helen Loo Yau, Post-doctoral Fellow Dr. Emma Bell, and Senior Scientist Dr. Daniel D. De Carvalho describes a DNA modifying epigenetic therapy that can transform immune killer T-cells into “super soldiers” by boosting their ability to kill cancer cells. Their findings could potentially enhance immunotherapy, a new paradigm in cancer treatment currently effective for a minority of cancer patients.

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Some patients respond well to immunotherapy, with their tumors drastically shrinking in size, but others respond only partially or not at all. Clinicians and scientists around the world are working to understand why immunotherapy only helps some patients. The research was published in Molecular Cell, on Feb. 19. Dr. De Carvalho, Associate Professor, Department of Medical Biophysics, University of Toronto, said:

“Our goal for the future is to use this strategy combined with other immunotherapies to enhance anti-tumor immunity. We imagine a future clinical trial where we collect T-cells from the patient for treatment with epigenetic therapy in the lab. This could expand the army of cancer killing cells effectively creating an ‘army of super soldiers.’These cells can then be re-infused into the patient, to potentially enhance their built-in immune response to the tumour.”

Dr. De Carvalho’s lab first observed an increase in T-cell infiltration in mouse tumors treated with epigenetic therapy. When they removed the T-cells, the therapy stopped working, suggesting that the T-cells were contributing to the treatment’s success. Intrigued by this finding, the researchers set out to apply this epigenetic DNA modifying therapy directly to T-cells in the laboratory.

The researchers discovered two specific genes that were activated by epigenetic therapy and were responsible for the T-cell immune cells becoming better at killing the cancer cells.
The researchers discovered two specific genes that were activated by epigenetic therapy and were responsible for the T-cells becoming better at killing the cancer cells. (Image: via Pixabay)

They isolated T-cells from healthy human donors, as well as from patients with melanoma, breast, ovarian, and colorectal cancer. Their results proved that epigenetic therapy enhanced these immune cells’ cancer-killing ability. Epigenetics works through the addition or removal of chemical “tags” to DNA. Much like detachable post-it notes, these tags help to specify which genes can be turned on or off. Simply, you can change the function of a cell using drugs that change these epigenetic tags.

In essence, the researchers found that an available chemotherapy drug removed specific epigenetic tags that were keeping genes off in a subset of key genes in T-cells. Removing these tags turned these genes back on, and acted to “turbocharge” the T-cells to become more effective killing machines. The researchers discovered two specific genes that were activated by the epigenetic therapy and which were responsible for the T-cells to become better at killing the cancer cells.

High-dimensional, single-cell mass cytometry analyses — a next-generation technology that profiles single cells and drug response — revealed an increase in the numbers of granzyme and perforin proteins, which T-cells use to carry out their killing function. When unleashed, like a lethal swat team, perforins are able to punch holes in a cell’s membrane to allow granzymes to enter into an infected or cancerous cell to finish the job of killing it. Dr. De Carvalho said the paper describes in detail the molecular mechanism of how the process occurs, adding:

“The T-cells became sort of ‘super soldiers’, with highly activated molecules — with bigger and better weapons — to destroy the cancer cells.”

Scientists looking at how our immune cells respond to cancer cells

A key novelty in the paper is using epigenetic therapy to influence the behavior of genes in the T-cell. Most research on epigenetic therapies focuses on their effect on cancer cells. However, this paper looks at how our immune cells respond, giving insight into how we can boost the anti-tumor activity of our immune systems. The emerging field of epigenetic therapy seeks to influence genetic activity without actually modifying the sequence of DNA — making this an exciting therapeutic avenue of cancer research. Dr. De Carvalho said:

“Genetic manipulation of immune cells for treatment is not trivial experimentally. It’s even more complicated and expensive in clinical implementation. Our work sets the stage for clinical investigations combining epigenetics with other immunotherapy strategies.”

This research was supported by the Canadian Institutes of Health Research (CIHR), the Princess Margaret Cancer Foundation, the Terry Fox Research Institute, the Ontario Institute for Cancer Research, the Canadian Cancer Society Innovation Award, and the Scotiabank Research Chair.

Competing Interests

Dr. Daniel De Carvalho received research funds from Pfizer and Nektar therapeutics. Dr. De Carvalho is co-founder and shareholder of DNAMx, Inc. Christian Klein is employed and owns stocks, patents, and royalties at Roche. John Stagg is a permanent Scientific Advisory Board member and owns stocks of Surface Oncology.

Provided by: University Health Network [Note: Materials may be edited for content and length.]

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