It's no secret that Gilead Sciences (NASDAQ:GILD) wants to be a big player in cancer treatment, or that it's prepared to use its deep pockets to do it. Last year, the company spent $11.9 billion to get its hands on Kite Pharma's Yescarta, a gene therapy for non-Hodgkin lymphoma. As far back as 2014, its cancer interest was evidenced by the launch of Zydelig, its treatment for chronic lymphocytic leukemia. Furthermore, Gilead Sciences revealed on its fourth-quarter conference call last month that it wasn't done bulking up its cancer pipeline and that it was especially interested in gene editing.

This week, the company put its money where its mouth is by inking a collaboration with Sangamo Therapeutics (NASDAQ:SGMO) that's potentially worth billions of dollars. Here's what you should know.

Game-changing treatments

Gene therapy that supercharges the immune system to fight cancer is the latest thing in cancer treatment. However, gene editing may prove to be an even better solution to winning the war against cancer.

Scientists in lab coats collaborating in front of a monitor displaying a double helix.

Image source: Getty Images.

In 2014, the FDA approved the immuno-oncology drug Opdivo for use in solid tumor cancer, and in 2017, it approved two chimeric antigen receptor T-cell therapies -- Yescarta and Novartis' Kymriah -- for use in blood cancer patients.

These immuno-oncology drugs deliver game-changing efficacy and manageable safety, but they're imperfect treatments. Opdivo and other drugs with the same mechanism of action, including Keytruda, don't work for everyone, and some patients develop resistance to them. Yescarta and Opdivo yield six-month response rates of about 40% in non-Hodgkin lymphoma patients, but they carry the risk of life-threatening cytokine release syndrome and neurotoxicity.

The drawbacks associated with these immuno-oncology approaches show there's still plenty of reason to continue innovating so that we can produce even better cancer treatments. Perhaps those better treatments will come courtesy of gene editing.

Technology that's providing us with a greater understanding of the relationship between genetic abnormalities and cancer is revealing DNA targets that, if manipulated, might control cancer.

The concept of rewriting genes sounds like science fiction, but it may be closer to reality than you think. For example, early stage research is under way at CRISPR Therapeutics, Editas Medicine, and Intellia Therapeutics that is based on an approach used by bacteria to cut the DNA of an invading virus to keep it from replicating. This approach -- CRISPR/Cas9 -- could eventually be used to regulate proteins in humans to tackle various diseases, including cancer.

CRISPR/Cas9 has received a lot of attention over the past couple years, but Gilead Sciences' interest isn't in CRSPR/Cas9 (at least, not yet).

Instead, Gilead Sciences is interested in another gene-editing approach that Sangamo Therapeutics is developing called zinc finger nuclease (ZFN) technology. On Thursday, Gilead Sciences signed a collaboration agreement with Sangamo Therapeutics to see if ZFN can be used to create allogeneic CAR-T gene therapies that can be used "off the shelf." In exchange, Gilead Sciences is paying Sangamo Therapeutics $150 million in up-front cash and up to $3 billion in developmental, regulatory, and sales milestones. Sangamo Therapeutics' will work with Gilead Sciences to craft both allogeneic and autologous anticancer cell therapies. 

Currently, CAR-T therapies like Gilead Sciences' Yescarta are autologous, meaning they rely on cells obtained from the patient. Specifically, CAR-Ts require removing a patient's T-cells and then sending them to a facility to be re-engineered so that they spot, bind to, and destroy cancer cells. It can take 20 days for this process to happen. 

ZFN works differently. Sangamo Therapeutics' approach involves attaching a nuclease that can cut DNA to zinc finger DNA binding proteins that recognize and bind to specific DNA sequences. This process allows Sangamo Therapeutics to cut DNA at specific locations to manipulate protein expression in a way that may reduce cancer proliferation. If the approach can be used to craft an off-the-shelf solution, patients could be treated immediately, and perhaps, with fewer risks.

There aren't any FDA-approved ZFN therapies on the market yet, but Sangamo Therapeutics does have ZFN drugs in human trials, and its research has not only won over Gilead Sciences but Pfizer, too. Pfizer licensed rights to work with Sangamo Therapeutics on a ZFN gene editing therapy for hemophilia A last year, and in January, it expanded its relationship to include research into ZFN gene-editing treatments for a type of amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

Will this work?

It's going to be a while before we know if Gilead Sciences and Sangamo Therapeutics' collaboration is successful in cancer, but we should get some insight into ZFN's potential later this year when Sangamo Therapeutics reports data from its most advanced trials in hemophilia A and MPS II, a rare genetic disease that results in the life-threatening buildup of complex sugars in the body.

If its hemophilia A and MPS II data show ZFN is effective -- and importantly, safe -- then it could further validate Gilead Sciences' decision to partner with Sangamo Therapeutics on new cancer treatments that may someday prove revolutionary.


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