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CAR T Cells via mRNA Update 7/2021

Date: July 2021
Author: Dr. Steven M. Albelda

Summary of Research in the Thoracic Oncology Laboratories at the University of Pennsylvania

Since 2016, the ROTZ Foundation has provided generous philanthropic support for the Thoracic Oncology Laboratories at Penn, directed by Dr. Steven M. Albelda.

This document is a summary of the past, current, and future status of the lab’s research project(s), highlighting the important contributions of these donations.

The lab has focused on developing novel and improved therapies for lung cancer and mesothelioma using genetically modified white blood cells (leukocytes) known as CAR (chimeric antigen receptor) T Cells. The patient’s own white blood cells are harvested. CAR T Cells are then manufactured from the patient’s white blood cells outside the body by using gene therapy to reeducate the patient’s white blood cells to target specific cancer cells. These CAR T Cells are then expanded in number and returned to the patient intravenously.

CAR T Cells have shown spectacular success in treating a number of blood cancers (leukemia, lymphoma, and myeloma) and are now FDA approved for these diseases. However, to date, they have been unsuccessful in controlling solid tumors such as lung cancer.

One key goal of our lab is to discover ways to use CAR T Cells to treat lung cancer. Thinking "outside the box", we have undertaken the following projects aimed at achieving this goal.

CAR T Cells Targeting Fibroblasts

The first project partially funded by the Rotz Foundation involved the development of CAR T Cells that attack tumors by targeting fibroblasts within the tumors. In lung cancer, fibroblasts form the scaffolding and provide nourishment for lung cancer tumor cells by supplying them with growth factors and by dampening down the body’s anti-tumor immune responses. We created CAR T Cells that attack a key protein on the surface of these tumor fibroblasts called "fibroblast activation protein" or FAP. We published 2 peer reviewed papers on this approach in 2015 and 2016, showing marked reduction in tumor size after treatment with the FAP-CAR T Cells.

Since then, our goal has been to initiate a human clinical trial using the FAP-CAR T Cells. This has been a challenging project because we needed to find just the right antibody that would recognize the high level of FAP on the cancer fibroblasts, but not cause damage to other normal cells that can express FAP at low levels. Funding from the ROTZ Foundation, especially in the early years, was absolutely critical in our ability to move this project forward. ROTZ Foundation support allowed us to generate the preliminary data needed to show the feasibility of this approach. With this data in hand, we were able to obtain significant funding from the National Cancer Institute and investment by the Tmunity Company to be able to take the project to clinical trial.

We are currently “tweaking” our final CAR constructs and are hoping to begin a human clinical trial for squamous cell cancer of the lung, mesothelioma, and for head and neck cancer within the next 18 months.

Developing CAR Cells that Use Natural Killer Cells Instead of T Cells

Our second project partially funded by the Rotz Foundation involved making CAR cells using a different type of white blood cell called a "natural killer" (NK) cell. These cells have an intrinsic ability to kill tumor cells, can support the function of the chimeric antigen receptor, and seem to cause less side effects when infused. We began by studying a NK tumor cell line called NK92 that could easily be grown in the laboratory and allowed us to make multiple genetic changes in the NK cells.

Unfortunately, after a number of years of careful study, we found that these NK cells don’t traffic well into tumors. In addition, since they are tumor cells, we must make sure that they cannot divide (and cause tumors) after being injected. This requires us to first give them high doses radiation therapy prior to injection. While this did prevent them from growing in a host, they only lasted a very short amount of time. Our animal studies showed some anti-tumor efficacy when we gave multiple injections, but we don’t feel they are effective enough to move forward to clinical trials.

Fortunately, this acquired expertise with NK cells is now going to be used in a new project, conducted in collaboration with Dr. Neil Sheppard in Dr. Carl June’s lab, to make CAR cells using freshly isolated NK cells from the patient’s blood. These studies are planned to start in the fall of 2021.

New Project: Developing a Way to Generate CAR T Cells Inside the Body with a Simple Injection of mRNA

The process of making CAR T Cells outside the body is very time consuming, expensive, does not always work, and requires the patients to be pretreated with chemotherapy drugs to reduce their own white blood cells (to “make room” for the infused CAR T Cells). To address this issue, we plan to take advantage of some new technology discovered at Penn to develop ways to make CAR T Cells inside the body, without the need for the complex exterior manufacturing process or for the chemotherapy pretreatment.

To do this, we are partnering with Professor Drew Weissman at Penn. Dr. Weissman was instrumental in developing the technology used in the mRNA COVID vaccine and is an expert in mRNA therapeutics. mRNA (messenger RNA) provides genetic blueprints for cells to make proteins. We plan to create a formulation very much like the COVID mRNA vaccine. We will coat mRNA encoding for the CAR with a shell of fatty material that will then be targeted to the T Cells by antibodies on the surface (see figure). When injected into the blood, the antibody will cause the particles to bind to the T Cells. The particles will then get taken into the cell, the fatty coat will dissolve, and the mRNA will direct the T Cells to make the CAR that will move to the cell surface. Because mRNA is relatively short-lived (unlike what we see with the standard outside-the-body produced CAR T Cells where expression is permanent), the cells will express this CAR for only 3-4 days. We will thus give repeated injections of the lipid nanoparticles/mRNA complexes to maintain activity over the desired period of time. We have done some initial experiments in mice that seem very promising. This is admittedly a high risk-high gain project, but if successful, would change the entire CAR T Cell paradigm, making them much less cumbersome and less expensive to produce, potentially safer, and thus open opportunities to treat many more patients.

Why the ROTZ Foundation Funding has Been so Important

The Thoracic Oncology Laboratory has funding from a number of sources, including government grants and research agreements with pharmaceutical and biotech companies. Traditionally, these funding sources are quite conservative and only want to fund "sure things" with lots of preliminary data. However, that is not how the discovery of cutting edge science works. There is a need to try new, creative, risky, and unproven approaches. Some succeed, but most don’t.

This "novel idea space" is where the Rotz Foundation has been of special importance to the lab by helping to support these more novel “high risk - high gain” projects needed to produce the preliminary data that can then be used to obtain government or industry support. For example, ROTZ Foundation funding was used to help support the FAP CAR T projects, ultimately leading to the NIH grants and industry support that will lead to human clinical trials.

More recently, the funds have supported the NK cell projects, and over the next year will be used to support the new project to generate CAR T Cells inside the body with a simple injection of mRNA. We are hopeful that these projects will also lead to government and industry support and ultimately to clinical trials.

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