Because of its high efficiency and accuracy, the CRISPR genome editing technique has recently emerged as a potentially powerful tool in the arsenal of cancer therapy.
What is Cancer?
When the cell becomes immortal and divides uncontrollably, such a condition is known as Cancer. In cancer, the cells divide even after the cessation of stimuli. Moreover, some cancerous cells break off from the primary site and began to grow cancerous cells in another part of the body – the phenomenon term is a metastasis. Cancer at this stage signifies that a large amount of damage is down and death is now inevitable.
Cancer arises either because of mutation in the tumor suppressor gene or it may in proto-oncogenes.
Available Treatment for Cancer
Currently, several methods and strategies available to cure cancer including surgical removal of cancerous cells or tumors, radiotherapy, and chemotherapy. These are used in different stages of cancer, but these therapies are not the final cure for cancer. Moreover, they are associated with drawbacks because they not only destroy cancerous cells but also healthy ones. Such treatments result body gets further weakened over time and there are reports of deaths occurring due to these therapies.
Cancer has several unique abilities like the ability to grow again from a single surviving cell. Moreover, tumors also become resistant to therapies. Furthermore, sometimes due to the location of tumors, surgical removal of tumors is not applicable. These are some of the discrepancies in current strategies related to cancer.
To overcome the current hurdles in cancer treatment, there is a need for an alternative and novel strategy. Moreover, as cancer occurs when there is a mutation in some specific genes i.e. tumor suppressor genes or proto-oncogenes. This makes CRISPR best candidate to target these mutated genes and treat cancer.
What is CRISPR?
CRISPR is a novel gene editing technique that has the potential to edit or eliminate more precisely than ever before the genome of almost any organism.
CRISPR primarily evolved as the bacterial immune system where it cut and later store foreign particle (usually viruses). Scientist hijacked this cut and paste property of CRISPR and later used as a gene-editing tool.
Explore more about CRISPR: What is CRISPR Cas9?
Can CRISPR Cure Cancer? Current Researches
Researchers at the Sichuan University, China, were the first to use CRISPR on cancer patients. The reports showed good results and these experiments are now into clinical trials for aggressive advanced non-small cell lung cancer.
However, a study published in Nature showed that a tumor suppressor gene so-called P53 prevents the action of CRISPR.
This changed researchers target from cancerous cells to immune cells. The aim is to make immune cells stronger, to able to recognize and kill cancerous cells. This is known is cancer immunotherapy.
Another study published in nature in 2018, where two research groups from the University of California, SA, and LA have successfully made chimeric antigen receptor T-cells or CAR-T cells. They did so by inserting CRISPR machinery and gene of interest into lab-grown human T-cells (the type of immune cells). They inserted these components via electroporation.
By this method, CRISPR corrected mutations in T-cells of patients with autoimmune diseases as well as modified and reprogrammed T cells to recognize and bind cancer cells more effectively. The CAR-T cells successfully recognized and targeted human melanoma cancer cells in mice models. This study paved new ways in cancer treatment where CAR-T therapy will completely replace chemotherapy, radiotherapy and other conventional ways in treating cancer.
In 2000, a famous and most cited paper by Douglas Hanahan and Robert Weinberg entitled “the hallmarks of cancer” discussed six main features of cancer cells. Now a research group from Australia showed that CRISPR is active in all the hallmarks of cancer and is trying to tackle cancer, by targeting different features of cancer cells.
Currently, the CRISPR clinical trials are carried out in Hangzhou Cancer Hospital, China, where researchers use CRISPR technology to knock out the PD-1 receptors gene from the tumor cells in esophagus cancer. These genetically altered tumor cells are then reinfused into patient bloodstream. Hence, to enhance the T cells anti-tumor activity.
PD-1 protein expressed on the surface of both lung and esophageal tumor cells. It instructs the body’s natural immune system (T-cells) not to attack.
By using CRISPR to knocking out, PD-1 is an ideal way to treat other cancer types too. Edward Stadtmauer leads the first CRISPR clinical trial in the US at the University of Pennsylvania. They are using this same approach to treat multiple myeloma, melanoma, synovial sarcoma and myxoid/round cell liposarcoma.
CRISPR-Based Companies involved in Cancer Treatment
There are several CRISPR based companies involved in CRISPR immunotherapies, like Editas medicine, Intellia Therapeutics, CRISPR Therapeutics. CRISPR Therapeutics has CRISPR based immunotherapy called CTX10, which is used for sickle cell anemia and beta-thalassemia. These companies are also moving forwards towards treating cancer via CRISPR.
Ethical and Safety Concerns
The main concerns using CRISPR for cancer, is what if things go wrong? like the case of Jesse Gelsinger, who was the first patient to die from adverse reactions towards gene therapy clinical trial for x-linked rare genetic liver disease. Similarly, the death of another patient, who was a part of gene therapy clinical trials for arthritis.
A study published from the laboratory of Allan Bradley at Wellcome Sanger Institute in England showed that CRISPR gene editing may be doing more damage than scientists thought.
Moreover, a Chinese scientist named He Jiankui, claims of creating a genetically edited baby via CRISPR. The claim has made the scientific community began to question CRISPR more.
Also, CRISPR is progressing too fast which is another concern that in one way or another soon CRISPR based immunotherapies may be used to develop deadly bacterial and viral strains.
Hopefully, CRISPR will be soon used as a novel cancer treatment that will overcome the current discrepancies. Moreover, it will also be able to negate the harmful effects of chemotherapy, radiotherapy and other conventional cancer treatments.
Explore More: 11 Diseases CRISPR Technology Could Cure!