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  • Writer's pictureElizabeth Welch

Let’s Talk about Cell and Gene Therapy

Like us, you’ve probably been hearing a lot about cell and gene therapies (CGTs) recently, from hypothetical use cases to FDA approvals. Promising to revolutionize treatment for patients across indications, CGTs have received increasing attention and capital investment over the past years. Wading through the myriad of CGT-related articles and resources, we want to briefly take a high-level look at the current state of CGTs in the US.

Let's Talk about Cell and Gene Therapy

With the shared goal of altering a patient’s biology, cell therapy and gene therapy occupy distinct, but overlapping, fields of medicine. For cell therapy, cells are transplanted into the patient’s body to replace diseased or damaged ones, modulate function of other cells, or eliminate dysfunctional cells (in the case of CAR-T cell therapy, for instance). These disease-targeting cells can either be derived from the patient and edited, or conversely developed from stem cells. While cell therapies can utilize a wide range of cell-modifying mechanisms—from protein expression to gene editing—gene therapy strictly considers therapies that alter a patient’s genome. As such, gene therapies harness gene editing technologies to address the underlying causes of genetic disorders, from turning off damaged genes to inserting beneficial ones. Gene therapies can be in vivo, whereby vectors deliver the gene editing system to the patient’s cells, or ex vivo, whereby patient’s cells are removed from the body, edited, and then transplanted back. Notice anything? Occupying the middle-ground between cell therapy and gene therapy, ex vivo gene therapy has also been referred to as gene-modifying cell therapy or cell-based gene therapy.

A little history: gene editing technologies trace back to the 1980s, if not earlier, with the discovery of Zinc Finger Nucleases (ZFNs). Followed by the development of TALENs in 2011, these two foundational technologies have since been surpassed by the now well-acclaimed CRISPR-Cas9 technology. First characterized for gene editing in 2012, the CRISPR-Cas9 system has since revolutionized gene editing, unsurprisingly accounting for the largest gene editing market share in 2022. Evolving from CRISPR-Cas9, emerging technologies like base and prime editors are further advancing the specificity of these systems, optimizing editing site selection and reducing off-target effects.

In 2017, Kymriah became the first CGT to be FDA-approved. As a CAR-T therapy now indicated for patients with follicular lymphoma, large B-cell lymphoma, and pediatric acute lymphoblastic leukemia, Kymriah is a customized treatment that genetically programs a patient’s T cells ex vivo so that, once infused back into the body, they recognize and destroy cancerous cells. To date, only 32 CGTs have been approved. Despite representing only 7% of novel approvals in 2022, CGTs have steadily been making up a larger proportion of approvals over the past five years. Furthermore, recent news articles have highlighted a recognized impetus by the head of the FDA’s Center for Biologics Evaluation and Research to usher gene therapies, particularly for rare diseases, through the clinic. Evidencing the wave of CGTs to come, there are currently over 1,500 ongoing clinical trials registered with, with 90% only in phase 1 and 2. Among these trials, the majority of CGTs are in oncology (59.8%), followed by cardiovascular (6.2%), immunology, (5.7%), dermatology (4.7%), neurology (4.3%), infections (4.0%), musculoskeletal (3.7%), and others.

While this brief synopsis covers merely the tip of the vast CGT iceberg, we'll be following along as CGTs continue to garner increased attention, especially among FDA regulators.

Are you interested in learning more about ongoing innovation in cell and gene therapy? Brooks Hill Partners is a life sciences consultancy and early-stage health tech venture capital firm that partners with passionate companies across the biopharma and healthcare landscape. Please connect with us to learn more about how we can help you today. For more information, visit and follow us on LinkedIn.  


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