This week we profile a recent publication in Molecular Therapy: Methods & Clinical Development from Lisa
Dreolini (pictured) in the laboratory of Dr. Robert Holt at Canada’s Michael Smith Genome Sciences Centre.
Can you provide a brief overview of your lab’s current research focus?
The Holt Lab is located at Canada’s Michael Smith Genome Sciences Centre at BC Cancer (GSC). The group uses cutting edge tools and methodologies to investigate the biology of cancer from several different angles. Focusing on the immune system, the group has used deep sequencing to survey T cell repertoire diversity at the resolution of individual clonotypes and are now using these methodologies to explore the role of T cells in cancer. They are also working to develop cancer immunotherapies using engineered T cells to selectively deliver cytotoxic payloads to bolster the anti-cancer immune response and to enhance tumour cell killing. The group employs their expertise in DNA sequencing and computational analyses to investigate the role of infectious agents in cancer development and were the first to demonstrate a strong link between the pathogen Fusobacterium nucleatum and colorectal cancer. Finally, they apply deep sequencing technologies to identify the spectrum of mutations in various cancer types, with a particular focus on tumour evolution and the identification of antigens for cancer vaccines.
What is the significance of the findings in this publication?
A promising new type of cell-based cancer treatment called CAR T-cell therapy exploits the power of the immune system to fight cancer. A patient’s T cells—key players of our immune systems—are taken from the body, trained to detect and eliminate cancerous cells, allowed to replicate in the laboratory to create an army of cancer-fighting cells, and then injected back into the patient where they carry out their search-and-destroy functions. While there is mounting evidence that these “one-time only” treatments are highly effective, the expense and complexity of production remains a bottleneck.
To grow in a laboratory, T cells require a rich source of nutrients and a warm environment—conditions that are unfortunately ideal for the growth of bacteria. Many precautions are taken during production of cell-based therapies, so contamination is rare. But when it does occur, a particular type of bacteria called Mycoplasma is often the culprit.
Prior methods for screening cell-based therapy products rely on replication of contaminating bacteria so that they can be seen under a microscope—a process that can take up to a month. The method, developed in the Holt lab and published in Molecular Therapy: Methods & Clinical Development, can be done in a day. Rather than looking for the bacterial cells themselves, they treat the samples like a crime scene, looking instead for DNA evidence that the bacteria are present.
Using DNA as an indicator instead of live bacteria is a big advantage. It circumvents the need for growing Mycoplasma bacteria within the laboratory, reducing the amount of time needed to screen the samples while also eliminating a potential source of contamination.
What are the next steps for this research?
Similar DNA-based screening methods have been developed elsewhere, but to be used on patient samples the methods must meet specific criteria as determined by Health Canada. The Holt lab developed a method with the required sensitivity, robustness and specificity for validation, demonstrating they were able to meet the detection limit of 10 bacterial cells per millilitre of sample reproducibly on a variety of different samples.
Sharing their method with the scientific community will enable rapid and cost-effective screening of cell-based cancer therapies across the country, facilitating efficient delivery of these life-saving therapies to patients enrolled in clinical trials.
This work was funded by:
This work was supported by BioCanRx (Biotherapeutics for Cancer Treatment funded by the Networks of Centres of Excellence), Canadian Foundation for Innovation and the BC Cancer Foundation.
To find out more about the Holt lab, visit their website and follow them on Twitter:
@holt_lab
www.bcgsc.ca/holtlab
