Cytocentric Visionary: Budd Tucker, University of Iowa

Part 2: Modularity is Key to Cell Therapy Process Flexibility

Dr. Budd Tucker is the Stephen A. Wynn Associate Professor of Regenerative Ophthalmology at the Stephen A. Wynn Institute for Vision Research, University of Iowa, where his lab is working on developing cGMP-compliant production of patient-specific retinal cell regenerative medicine using Xvivo Systems from BioSpherix. The transcript was edited for length.

See Part 1 of Alicia Henn’s interview with Dr. Tucker “With iPSC and CRISPR, Leave Nobody Behind, Leave Nobody Blind” here

Alicia Henn

So why pursue autologous rather than an allogeneic therapeutic?

Budd Tucker

That’s an interesting subject that a lot of people argue over. An allogeneic approach obviously is perfectly suited to current manufacturing strategies. So if you could have a single cell to treat a large number of people then you could generate that cell and expand that cell with traditional manufacturing approaches. So you could have a cGMP CRO-based manufacturing facility make trillions of cells for you that you could then potentially freeze, ship to sites of therapeutic trials, and deliver them to patients.

The problem with that entire strategy is that we have an immune system.

One of the major advantages of the advent of the iPSC was the ability to do autologous therapies. You can still say “Well it’s going to be difficult, it’s expensive, the cells have to be generated from every patient in need so the manufacturing strategy isn’t going to work. We can no longer do the traditional scale up that people always think about when you’re talking about manufacturing.”

Well that’s just the problem right?

This is biology! We shouldn’t say, “Manufacturing is not well suited to it so we can’t use an autologous approach.” We need to say, “We need an autologous approach because we all have immune systems.”

Until some day that it’s presented to make me believe otherwise, autologous is the way it should be done and what we need to do is change the manufacturing strategy.

Gene therapy is well suited for traditional manufacturing because you can have a bioreactor produce a huge batch of virus to treat all of the patients with that disease-causing gene. That said, the genes we’re most focused on are so rare that even then the treatments are going to have to be fairly expensive. So there is still obviously, for rare diseases, room to be doing this in a BioSpherix unit as a small cGMP facility for small batch products.    

So this is really what drew me to the BioSpherix Xvivo Systems that we have. This is still a scale up, it’s just a different type of scale up; scaling up the process, not scaling up a single batch to treat multiple people. So we are devising new strategies that are well suited for autologous cell transplantation.            

AH

I see and you think the Xvivo System is the way then to be able to get that kind of scale-up or scale-out?

BT

Yes. The reason why I was attracted to the Xvivo System in the first place came to me from the cell reprogramming side.

So when we first started out in the early iPS cell days in 2006/2007, and this was purely a right place, right time, I became a post doc in 2006 and literally months after I became a post doc, Yamanaka published the first iPS cell paper. Then George Daley, came to give a talk at our institution. He essentially jump-started my career. I was definitely in the right place at the right time. 

Human iPS cell generation in the early days was not an easy thing to do. Reprogramming efficiency was so low it was very difficult to do anything with iPS cells unless they were generated from very early skin-derived fibroblasts, meaning from a young patient. Yamanaka published a paper to show that iPS cell efficiency generation could be increased by culturing the cells in low oxygen. At that time we were actually using low oxygen in Mike Young’s lab for expanding a human retinal progenitor cell population.

If you culture cells under physiologic oxygen, meaning three to five percent, then you could much more easily reprogram fibroblasts into iPS cells. So that’s where we started.

The problem with that strategy in a traditional laboratory is that it’s not consistent. Cells come out of a little hypoxia chamber in our incubator and go to our normal hood to have the media changed, obtain images, etc., and then we would put them back into low oxygen. So what we had was this jump from 5% oxygen to 20% oxygen, and then back down to 5% on a daily basis.

When the Xvivo System came along it completely changed the entire strategy, with the Xvivo we can culture under any oxygen tension and feed, image and handle our cultures without large oxygen fluctuations. That was really the big thing that pointed me in the BioSpherix Xvivo direction.

But, the isolation component of the Xvivo System is the biggest advantage for me. From an FDA or a manufacturing standpoint, I think you’re going to be seeing a lot more of these cell isolators. The Xvivo System can be placed in normal facilities that don’t use the same ISO classifications that would be needed if you were doing open air culture.

That is a dual advantage that I wasn’t even aware of when we first started because our first BioSpherix unit was purely purchased because of its oxygen/atmospheric conditioning control and it turns out that that’s just the minor advantage.

AH

So you chose the Xvivo System first for the oxygen and second for the isolation?       

BT

That’s exactly why we did it and the isolation is just key. It’s sort of interesting because the other part of the isolation, which I hadn’t touched on and why I never like to say just “oxygen control”, is that it’s really atmospheric conditions.

All or most of the other isolators on the market, are really tailored for, say, drug production or something of that nature. None of them are maintained at 5% CO2, 37ºC. These aren’t common parameters that most isolators use because most isolators are essentially used to protect the human and the product from each other. But when the product is a drug, it’s not as critical to keep something at 37ºC or at 5% CO2, 5% oxygen as it would be with an iPS cell line. So the environmental control in this isolator is really the key reason why I was drawn to it.

I’ve got to tell you the reason why I think it has stuck with me since the first two Xvivo units that I built into our clean rooms in 2014/2015. The most attractive thing is the modularity.

The other big difference between BioSpherix isolators vs. traditional stainless steel isolators is that I can rearrange these modules however I want. That is a huge advantage when developing a strategy for autologous cell replacement. In particular, it allows me to fit my strategy to an existing space. That’s a very rare ability in the isolation world.

AH

How much do you think that control of the in vitro and cell handling environment can contribute to the reducing the kind of variability that can delay cell production process development?

BT

I think it’s huge. The more control you have, the better. From an FDA or a regulatory standpoint,  your ability to control the conditions that a cell would see and maintain that over the course of production and then have records that you could present to the FDA in an IND or similar application, is very difficult in an open room system.

It’s not only the ability to control; it’s the ability to monitor what you’re controlling, which the BioSpherix units do really well. I can tell you exactly the product’s humidity, temperature, the CO2, the O2, the particles, etc. at any point in time. So from a FDA auditor’s standpoint, it is a dream! Anything they ask me, I can show them what the cell saw.

In an open air cleanroom system you have little control of what goes into or happens in an open laminar flow biosafety cabinet; especially things like temperature, particle counts, VOCs, and some of these compounds that are known to be toxic to cells in clean rooms. We can monitor all that in real time with our BioSpherix cGMP units

AH

And you’ve been able to customize your units to your specific process.

BT

There is no BioSpherix unit on the face of the Earth like the ones we have. The first two BioSpherix units we got we built into the walls of an ISO class 6 clean room. The engineers at BioSpherix worked with us to custom designed flanges for these units that we could use to bolt them to the wall with their backs exposed to a non-clean service chase. They can completely be serviced from the back without breaking sterility. The team at BioSpherix has just been outstanding.

I absolutely see the BioSpherix units being critical for our process from both sides, in both the gene and cell production.

AH

We certainly feel privileged to be a small part of your efforts to bring the power of stem cells, gene augmentation and CRISPR-based genome editing to the patients that need them.

Thank you for your time and your thoughts, Dr. Tucker.

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