The Challenges of Developing CAR-T and cas9 Therapies

Cell therapies, such as CAR-T treatments, have transformed how we can treat a variety of diseases and conditions, but there are still limitations to its application in solid tumors and other cancers. In this article, Jing Zhao, Chief Business Officer of Refuge Biotechnologies, will discuss how dead cas9 (dCas9) can be leveraged to completely control gene expression without making permanent edits as seen with CRISPR technology, the clinical strategy for advancing this new platform and the potential manufacturing hurdles that need to be overcome. 

Moe Alsumidaie: At Refuge Biotech, you are creating intelligent cell therapies to fight cancer. Could you tell me more about your technology?

Jing Zhao

Jing Zhao: Refuge is a synthetic biology company that incorporates cell therapy and gene engineering to develop therapies that could work in a variety of cancers, including solid tumors. 

We call it synthetic biology because we think of it as having pieces. The idea is we can link together an external stimulus, by use of a cell surface receptor, to a resulting action at the genetic level within the cell. We pair a cell surface receptor with what's known as d-CAS, which cannot cut or edit the genome. This new CRISPR technology is known today as CRISPR interference. We can link the external stimulus or signal directly by the CRISPR interference molecule and signaling pathways into the cell nucleus so that you can bypass the cells’ own signaling and effectively have the cell do precisely what we program it to do.

One area where CRISPR interference differs from CRISPR is that it no longer cuts DNA. Our technology modulates genes rather than edits genes. This may be a safer approach that avoids various toxicity risks and errors that other CRISPR technologies face. 

MA: So, you programmed the T cells to do a specific function and attack a cancer cell?JZ: You can think of it as a circuit-there’s an input, then there's signal transduction, and then there's an output. We use CAR-T to link together the CRISPR interference, so it is more powerful and can then modulate specific genes. For example, PD-1 may be an input, and our cell therapy will then down-regulate PD-1 or direct a kill attack on the tumor itself. 

You can also have the effect of a combo therapy within the same T-cell. Our technology allows us to multiplex many genetic modulations so that you can actually hit multiple genes at multiple locations on the DNA at the same time. You can have a downregulation of the PD-1 gene, as well as the LAG treating the TIM-3 molecule. Therefore, you're actually getting the efficiency of all of these particular targets together with the CAR therapy at the same time. And we are hoping this allows us to be able to overcome many of the challenges that are currently causing cell therapies to be less efficacious in solid tumors than it could be.

MA: What clinical trial challenges are you expecting? JZ: We need to make sure we put our manufacturing ducks in a row. The technology is, from a manufacturing perspective, similar to cell therapies today, but we want to make sure that it is actually a very highly complex process compared to the traditional manufacturing of drugs because it involves so many more parties. The challenge involves creating an efficient manufacturing infrastructure and clinical operational process that will work well with sites and patients.

MA: Since it can be challenging working with many different departments, would you be leveraging the institution's infrastructures to prepare the T-cells, or would Refuge do that and then ship those back to the site?JZ: This very much will depend on the center that we work with and the capabilities that they have there. To code for all of these elements, there will need to be a range of plasmids that can be used to make an antivirus. We will work with commercial manufacturers to make those viruses and plasmids. But when it comes to the cell piece itself, we are talking about patients who will be at medical centers. We have to consider how efficient it will be to have the patient in one place, and then to have the virus and a lab to transfect the cells in another, and then we will need to give the cells back to the patient. Ideally, we would work with clinical centers that have both the hospital and the cell manufacturing capabilities.

MA: How specified or personalized can this approach be?

JZ: It is entirely personalized, but not so personalized that it's only going to work on one particular individual CAR-T. It is an autologous therapy, like current CAR-T therapies today, because there are consistent targets in the pathology of cancer that we can target that aren’t so personalized to one individual. For example, our lead product can recognize the HER2 molecule for all tumors that are expressing or overexpressing HER2. We will then regulate other pathways, for example, PD-1, LAG-3, TIM-3, as well as a multitude of others that we can hit. There comes a question of which ones, and how many do you need? And that's where this concept will then come into how personalized it will become. We are looking at the different tumor types and figuring out which combinations will make the most sense. 

MA: What sorts of regulatory pathways exist for this novel technology, and what is your development approach when it comes to addressing these regulatory challenges?JZ: it’s interesting because the technology could be compelling but it’s new, and some aspects of the structure are very novel, so we first will down-regulate one gene at a time. The FDA can then better understand the backbone of the technology before we add more elements to it and make it more complex. In general, CRISPR technologies and cell therapies are relatively new for the FDA, and they don’t have decades of experience with it, like other cancer therapies.

MA: What are the indications you potentially are looking into besides cancer-perhaps HIV? JZ: In terms of additional areas that we could apply this, we want to look into infectious diseases, rare diseases, possibly some metabolic diseases, and cardiovascular applications. As long as cell therapies are applicable, we're here to be able to combine multiple treatments into a single therapy to make that cell therapy better. We don’t know the limit to this technology just yet. 

Moe Alsumidaie, MBA, MSF, is a thought leader and expert in the application of business analytics toward clinical trials, and Editorial Advisory Board member for and regular contributor to Applied Clinical Trials.