September 29, 2021 PAO-09-21-CL-13
Ashish Patel (AP): For about 10 years, our lab has been developing a novel cell therapy for cardiovascular disease, in particular, for patients with peripheral vascular disease. We focus on engineering subsets of tissue-remodeling monocytes/macrophage using mesenchymal stem cells.
When the COVID-19 pandemic first emerged, it became clear that a significant percentage of patients recovering from severe SARS-CoV-2 infections — 10–20% — developed fibrotic interstitial lung disease, which is essentially a result of lung scarring that leads to restriction of lung function. This issue is not unprecedented; literature reports suggest that approximately 30% of patients that were infected with other coronaviruses (SARS, MERS) suffered from lung problems up to one year after recovering.
Previously, we obtained promising preclinical data for our new cell therapy in ischemic legs. When reviewing these data, we realized that our new treatment appeared to exhibit antifibrotic function in vivo. We thus saw the potential for these cells to benefit recovered COVID-19 patients suffering from interstitial lung disease and began work to evaluate that potential.
Our first step was to conduct laboratory tests to confirm the antifibrotic effect that we had observed with our cell therapy. On the basis of those positive results, we decided to put our original program on hold and repurpose our therapy as a treatment for previously healthy patients who survive COVID-19 but go on to develop fibrotic interstitial lung disease following recovery, which appeared to be the more pressing and acute need.
AP: There are actually around 250 different types of interstitial lung diseases, but just two commonly used approved treatments for, usually, idiopathic pulmonary fibrosis. Their primary aim is to stop the progression of lung fibrosis. Numerous biologics are in clinical trials as well and have been tested worldwide. While these drugs are available, they are limited with respect to their ability to treat other types of lung fibrosis. Our therapy is the first to apply cell therapy to fibrotic disease following COVID-19.
AP: Monocytes are highly plastic cells that account for a relatively small proportion of the immune cell content in humans. Their function is to act on the immune system and combat infection, and they do so by becoming macrophages when they enter tissue. Macrophages eat cell debris and dying material when in the right state.
Monocytes do not exhibit anti-fibrotic activity when circulating, but they can become anti-fibrotic when they enter certain tissues in a certain state. Therefore, by controlling the conditions that monocytes are exposed to, it is possible to switch them into being anti-fibrotic, pro-angiogenic, pro-arteriogenic, and so on.
Controlling this switch has been the focus of my research group for many years. We use the inherent ability of mesenchymal stem cells (MSCs) to modulate other cells. Specifically, the MSCs modulate the monocytes into what we call tissue-remodeling monocytes, which are angiogenic and arteriogenic. In animals, they have been found to have an ability to reverse post-ischemic and post-inflammatory fibrosis. This type of monocyte is rare in normally circulating blood (~2%), which isn’t practical for generating a therapy.
We overcome this issue by manufacturing monocytes primed to exhibit anti-fibrotic activity outside of the patient and then reintroducing them into the bloodstream intravenously, where they produce proteins that break down scar tissue, then eat up their debris.
AP: By 2019, we had completed our initial pre-clinical work for ischemia and received funding from the Rosetrees Trust to perform engineering runs and scale up the cell therapy targeting peripheral artery disease. We identified RoosterBio as our company of choice to provide the MSCs needed for the key step of modulating the monocytes toward this tissue remodeling phenotype and function. We were about to start work in our Good Manufacturing Practice (GMP) unit at Guy’s Hospital, which is part of the National Institute for Health Research (NIHR) Guy’s and St Thomas’ Biomedical Research Centre (BRC). In March 2020, essentially all non-COVID-19–related research was paused to divert resources to the pandemic response .
Once we demonstrated that our candidate cell therapy did indeed have anti-fibrotic activity, we were fortunate to receive funding from the NIHR Guy’s & St. Thomas’ BRC and King’s College London to instigate a phase I study in recovered COVID-19 patients who the develop fibrotic interstitial lung disease. However, it was imperative that we could show the ability to reliably and reproducibly engineer these cells at the required scale and obtain the necessary regulatory approvals. The goal was to do that in 12 months, which was much shorter than the two to three years originally planned for the study for peripheral arterial disease.
Within the Advanced Therapy Unit at King’s College, our team of production scientists and quality control experts put their heads together and directed a lot of resources into the manufacturing and engineering work. One of the big hurdles when scaling production for this therapy is the use of MSCs. Our original plan required development of a working cell bank of the right MSCs that could modulate patient monocytes. This would probably have taken around 12–18 months or maybe longer.
With RoosterBio’s “off-the-shelf” MSCs, we believed that our goal could be reached, since they enabled a dramatic reduction in the development timeline. RoosterBio’s well-phenotyped cells are produced with a well-defined process using a highly qualified cell line that has been approved by the U.S. FDA. Using their cells and robust processing, it was possible to very quickly generate a working cell bank.
With the cell bank in hand, we had the ability to start manufacturing these monocytes from blood in a scalable process. In fact, we had our working cell bank generated within six weeks from moving the process into our GMP unit. The next step was to seek regulatory approval for a phase I trial. The entire process took just eight months.
AP: One of the primary challenges was to ensure that all the Chemistry, Manufacturing, and Controls (CMC) requirements for Investigational Medicinal Product (IMP) filing were met. The MSCs from RoosterBio come with all of the necessary documentation and historical certification. This significantly reduced the volume of qualification work we needed to do.
A second major challenge was scaling the manufacturing process, which can be difficult when using adherent cell culture. RoosterBio had a set process wherein everything was comprehensively established and consistent. They can predict how many cells you will have at a certain timepoint, so we knew in advance what to expect. This gave us a lot of encouragement, as well as faith in the process.
Our process development team benefited greatly from using an established process, because adherent cell culture was not an area of expertise for our team at the time. The RoosterBio cells also come with the media and a recipe needed to take one vial and generate 50, so our team were able to rapidly train themselves up on scaling the adherent process.
AP: Absolutely. Our unit didn’t have much experience working with huge volumes of media and then needing to reduce them. Scaleready’s Lovo technology enables the reduction of cell cultures, and the company offered us full support. With their help, it was possible to very quickly learn to volume reduce our cell cultures.
Miltenti Biotec have previously provided expertise on process development and scale-up from the lab to the GMP setting for our other products. They helped us in developing the process for isolating the engineered monocytes.
One of the most important contributors to the project was the team in our GMP unit. They had to be tremendously agile and learn new processes that they had no previous experience performing. And they did learn very quickly to adapt to new technologies and effectively leverage them for the project, which has been essential to our success.
AP: We are still in the early days of this project, with five patients recruited for our phase I safety study. They have all received autologous ex vivo cultured monocytes, and we are at the three-month follow up point for all five. Time will tell whether it’s effective and whether or not their lung function improves.
The treatment seems to be safe in the short term, and now we need to confirm that it is safe in the medium and long term. If we can do that and get indications of efficacy, then I would like to conduct a randomized, controlled trial that incorporates a dose escalation study to identify the optimal dose to deliver to patients who have post-COVID-19 interstitial lung fibrosis.
Monocytes cannot be delivered allogeneically. There are researchers working to develop inducible pluripotent stem cells that could be used to generate monocytes with their memories “stripped”. So it may be possible someday to generate off-the-shelf monocytes. MSC therapies certainly can be allogeneic, although we are currently using these to educate autologous cells. We are very interested in the direct delivery of allogeneic MSCs and have some interesting preclinical data with these cells.
AP: The inclusion criteria for this trial were people with no previously diagnosed lung disease that, after recovering from COVID-19 were diagnosed — by a respiratory multidisciplinary team — with interstitial fibrotic lung disease. We are collaborating with Dr. Alex West, who leads our excellent Interstitial Lung Disease service at King’s Health Partners. Five of his patients were recruited for the phase I study, which is primarily to evaluate the safety of the cell therapy. Follow-up investigations are being conducted for each patient at three months, six months and 12 months.
We began recruiting at the end of April 2021 and completed all five treatments in June 2021. That is quite rapid, which can partially be attributed to the desire of these incredible patients (who have already been through so much) to participate in the study. They were all otherwise healthy people who now really struggle with the usual activities of daily living.
AP: Yes. For this trial, patients undergo lung function tests at three months, six months, and one year. They are also completing six-minute walk tests and quality-of-life questionnaires. At six months and one year, they will each also have a CT scan of their lungs.
These are the typical endpoints in clinical trials for other types of lung fibrosis, so we are following that model. A later-phase trial would be very similar in the sense that we would have very early follow-up with a clinical test for lung function, which is the main test to show efficacy, as well as high-resolution CT scans.
AP: I’ve been working closely with my colleague Professor Bijan Modarai on tissue-remodeling monocytes/macrophages for years, particularly for the ischemic leg. There are also other stakeholders within Guy’s & St Thomas’, including the National Institute for Health Research (NIHR) Biomedical Research Centre, the Rosetrees Trust, and the British Heart Foundation Centre for Research Excellence at King’s College London.
One thing that is really special about this trial is that it has really been homegrown. The clinical trial materials are produced within our NIHR Guy’s and St. Thomas’ BRC and supported by our facilities and staff. Our Advanced Therapy Accelerator, which was launched on June 11, 2021, provides this type of environment and facilitates the development and manufacture of advanced therapies.
AP: The difference with COVID-19 patients is that we know the fixed point in time when the initial lung injury occurred, so the fibrotic process is in its early stages. With other lung conditions, there isn’t always a way to know how long the patient has had that condition. So, for the moment, we are focused on the phase I trial to evaluate safety. If we determine it to be safe, we would like to continue the respiratory work with a larger phase IB/IIA trial to evaluate its efficacy.
If we can show that the new cell therapy is effective at treating interstitial lung disease in recovered COVID-19 patients, then it would be really exciting to consider studies in patients who have other types of interstitial lung disease. It would be interesting to evaluate the therapy in these more chronic conditions versus a condition where there’s an acute lung injury. In our preclinical models, we focused on the acute inflammatory response that occurs after an injury to tissue, which involves a defined point of neutrophil and monocyte infiltration. For the lung conditions with a different pathological process that have longer onset, we will need further preclinical data to know whether this type of therapy might be effective.
We have had an incredible response from the public about the potential for this new cell therapy to treat other lung conditions, and my colleagues are very interested in developing similar trials for other types of interstitial lung disease. We are working closely together to develop the funding and to explore running other trials for different types of untreatable lung conditions, or at least lung conditions where the treatment has not been that effective in reversing the condition.
Of course, since our original aim for the therapy was for tissue remodeling in ischemic tissue, my long-term aim is to return to that initially planned clinical trial for the patients I look after who have peripheral artery disease. There is a lot of work to do in that area. We are pushing forward on that front and aim to explore using these cells in this patient cohort in the very near future.
Further work is needed to see whether this type of anti-fibrotic treatment can be applied to other organs, including the liver, kidney, and heart. If we could show that these cells not only stop progression but actually reverse some of the fibrosis by removing the scarring, then the potential to treat other fibrotic conditions could be very exciting.
For lung fibrosis, I have really enjoyed collaborating with some really talented respiratory academics and physicians –– something that may never have happed if it wasn’t for the re-purposing of this therapy. For the future peripheral artery disease study, we will work closely with other cardiovascular and vascular surgeons and scientists. I am always keen to collaborate with other researchers working in their respective fields and I’d be delighted to work closely with anyone who wants to make that happen.
Ashish Patel is a Clinical Senior Lecturer in the School of Cardiovascular Medicine & Sciences at King’s College London and Consultant Vascular and Endovascular Surgeon at Guy’s and St Thomas’ NHS Foundation Trust, London, UK. His British Heart Foundation-funded Ph.D., focusing on monocyte/macrophage biology in tissue remodelling, was awarded in 2013. He completed his Higher Surgical Training in General & Vascular Surgery as a Clinical Academic Lecturer at King’s College London & Guy’s & St Thomas’ NHS Foundation Trust. During this time, he received an Academy of Medical Sciences Grant and the Circulation Foundation’s George Davies Visionary Award. Dr Patel’s research interests are focused on the bench-to-bedside development and translation of novel cardiovascular advanced therapies, particularly for the treatment of peripheral arterial disease. He is an investigator within the BHF Centres of Regenerative Medicine and a Phase I accredited Principal Investigator at Guy’s & St Thomas’ NHS Foundation Trust. His research is funded by the Royal College of Surgeons, Rosetrees Trust, Advanced Therapies Network and the Frances and Augustus Newman Foundation.