Metabolic Conditioning Improves Potency and Accelerates Cell Therapy

Metabolic conditioning is emerging as a powerful strategy to enhance the potency, persistence, and manufacturability of next-generation cell therapies, providing new hope for hard to treat cancers.

By Yelena Bronevetsky, PhD

Immuno-oncology cell therapies have significantly improved outcomes for patients with hematological malignancies, but this success has yet to be widely replicated in solid tumors, which account for the vast majority of cancer diagnoses. Globally, researchers are working to enhance the effectiveness of these therapies and expand their benefits to more patients. 

However, even in blood cancers, the most effective CAR T cell therapies currently benefit only a small proportion of those treated (1). Between increasing that proportion and addressing the critical need of patients with solid tumors, many teams are turning to genetic engineering techniques to develop the next generation of cell therapies. Major research efforts are focused on designing constructs that more precisely target tumors or modulate signaling pathways linked to T cell exhaustion.

But there is another approach that could be simpler, more reproducible, and more amenable to rapid manufacturing: metabolic conditioning. Increasing evidence shows that growing cell therapies under conditions that better reflect those in the tumor microenvironment (TME) leads to greater persistence and potency. The TME has a unique gradient of lower pH, lower dissolved oxygen, and higher pressure that is not reflected in standard manufacturing approaches, but that is absolutely critical to optimizing metabolic fitness.

Metabolic conditioning

This approach can be thought of as the “elite athlete” model. Athletes at the top of their game train for the conditions they expect to face in competition, whether that’s a tennis player mastering a grass court ahead of Wimbledon or a marathoner running on steep hills before a race in San Francisco. In much the same way, autologous cell therapies receive their training in incubation platforms prior to infusion into the patient. If the conditions in these incubators are a poor substitute for the harsh, hypoxic, high-pressure TME, then it’s no wonder that cell therapies fail to work effectively in vivo.

For example, researchers have found that CAR T cells designed to target the Receptor Tyrosine Kinase-like Orphan Receptor 1 (ROR1) protein and cultured under standard incubator conditions appear to have strong tumor-killing potential when measured with in vitro assays at non-physiological, ambient conditions (2). However, when the cells are transferred into tumor-bearing animals, these CAR T cells successfully reach the site of the tumor but fail to elicit the expected anti-tumor response. Instead, in vivo analyses show that these cells have poor potency and persistence, and their use is quickly followed by disease progression, indicating that the CAR T cells had become dysfunctional when facing the TME. 

True metabolic conditioning can be performed with advanced incubation technology that offers more customizable settings than standard devices, such as the ability to precisely reduce oxygen levels. By creating more physiologically relevant conditions in vitro, researchers can better prepare cells for the suppressive forces they will encounter when they reach the TME. 

This approach flies in the face of conventional wisdom, which generally tells scientists to expand cell therapies under conditions known to make cells grow and divide quickly. But plenty of data supports the idea that coddling cells during their time ex vivo does not produce cell therapies with the same levels of persistence and potency that are seen with cells that have adapted to a hostile environment. For example, expanding cells in low-oxygen conditions while T cell activation is taking place has been shown to increase cytotoxic function when the cells are returned to the body (3). 

In separate work, restricting glucose availability during cell culture has been shown to enhance anti-tumor activity, while other modifications, such as adjusting amino acid composition in the media, have been linked to improved efficacy against solid tumors (4-6). Metabolic conditioning also extends to the cytokine composition of cell culture media. While the widely accepted IL-2 regimen produces maximal growth in vitro, the use of alternative cytokines, including IL-7, IL-15, and IL-21, triggers higher potency and persistence rates in vivo, despite reduced expansion in culture.

Although the immuno-oncology community’s understanding of metabolic conditioning is far from complete, all of these studies indicate that the approach could be very promising for the development of higher-performing CAR T therapies. This would be a boon for many patients with cancer, including those with solid tumors.

Rapid manufacturing

The benefits of metabolic conditioning may also extend to another major goal in the cell therapy community: shortening manufacturing timelines. With higher-potency cells, clinical doses could require fewer cells, perhaps reducing the billions of cells needed for current cell therapies to millions. This could reduce the cost of each therapy by tens of thousands of dollars, accelerate clinical trials, and make it possible to get therapies into patients faster, before they become too ill to benefit from them.

In academia, researchers are already pioneering rapid manufacturing approaches that accelerate the standard production timeline by a week or more. Major pharmaceutical companies are also working to reduce manufacturing times, often evaluating manual processing workflows that may not be compatible with downstream clinical manufacturing requirements. For use with FDA-approved therapies, an automated approach for metabolic conditioning and manufacturing will almost certainly be necessary.

Looking ahead

The limitations seen with the current generation of cell therapies may be better addressed through metabolic conditioning programs than through extensive rounds of genetic engineering. By creating culture conditions that better represent in vivo conditions, particularly the harsh environment surrounding tumors, cell therapies can be given a greater ability to thrive when introduced to patients. This includes reducing oxygen, increasing pressure, and adjusting the cytokine composition of culture media to acclimate cell therapies to the TME, making them more potent and persistent cancer fighters. 

These benefits could also enable rapid manufacturing processes that could reduce costs, shorten time to treatment, and allow therapeutic developers to scale dose production to reach more patients in need. Overall, it is possible that an approach based on metabolic conditioning could empower developers to overcome some of the biggest hurdles currently facing cell therapies for immuno-oncology.

This article was contributed by Yelena Bronevetsky, Director of Product Management at Xcell Biosciences. 

See the original publication in Drug Discovery News

References 

1. Cappell, K.M. & Kochenderfer, J.N. Long-term outcomes following CAR T cell therapy: what we know so far. Nat Rev Clin Oncol 20, 359–371 (2023).

2. Srivastava, S. et al. Immunogenic Chemotherapy Enhances Recruitment of CAR-T Cells to Lung Tumors and Improves Antitumor Efficacy when Combined with Checkpoint Blockade. Cancer Cell 39, 193-208.e10 (2021).

3. Cunha, P. P. et al. Oxygen levels at the time of activation determine T cell persistence and immunotherapeutic efficacy. eLife 12, e84280 (2023).

4. Klein Geltink, R.I. et al. Metabolic conditioning of CD8⁺ effector T cells for adoptive cell therapy. Nat Metab 2, 703–716 (2020).

5. Zhang, Y. et al. Enhancing CD8⁺ T Cell Fatty Acid Catabolism within a Metabolically Challenging Tumor Microenvironment Increases the Efficacy of Melanoma Immunotherapy. Cancer Cell 32, 377-391.e9 (2017).

6. Geiger, R. et al. L-Arginine Modulates T Cell Metabolism and Enhances Survival and Anti-tumor Activity. Cell 167, 829-842.e13 (2016).