Broader Trends in Cell and Gene Therapy

This is the second part of an interview with Roger Hajjar, MD. For the first part, click here.

Although gene therapy modalities, especially adeno-associated virus (AAV) vector-based gene therapy, and cell therapy modalities, especially chimeric antigen receptor T-cell (CAR-T) therapy, have become well-established in the world of medicine, innovation in the field continues to be an important trend. At the American Society of Gene & Cell Therapy (ASGCT) 28th Annual Meeting, held May 13 to 17, 2025, in New Orleans, CGTLive® spoke with Roger Hajjar, MD, the director of Mass General Brigham established its Gene and Cell Therapy Institute, about his thoughts on current trends in cell and gene therapy research.

With regard to gene therapy, Hajjar highlighted the importance of research into more specific tropic vectors and novel vector systems. With regard to CAR-T, he brought attention to the potential of in vivo CAR-T therapies. He also touched on innovations in in vivo gene editing.

CGTLive: Taking a broader view, are there any trends in the field of gene therapy right now that particularly excite you?

Roger Hajjar, MD: Gene and cell therapies have always been found to be too expensive, too complicated to actually produce as GMP grade material, and overall the field has been focusing on better vectors so that you don't need as much to deliver, lowering eventually the cost of goods; safer vectors, so that by being very targeted at a smaller amount, you need less of them, and then you have less side effects; and in general, process development that's going to be more effective at producing vectors or cells at much higher quality and much higher scale. Scaling up has become quite important.

So we see at ASGCT this year, different areas where these are being addressed. For vectors, we see more and more specific tropic vectors that are targeting organs with smaller amounts and less safety issues and, of course, lower cost of goods. What also has been emerging is the fact that we now have not just the usual vector systems, but novel vector systems that are coming on the stage. I think it's exciting to hear about the progress in these anelloviruses as a novel vector system (anellovectors), the bocaviruses, and others that are now increasing the vector systems that can be used for delivery.

What about cell therapy?

In terms of cell therapy, CAR-T clearly has been a major focus across
different disease areas. Obviously it started with liquid cancers and now has expanded to solid tumors and other inflammatory diseases, and we're seeing more and more sophisticated types of cargos for the T-cells that are becoming more and more effective. So I think there's clearly more progress that we will see in the CAR-T world, especially from the types of cargo that they're carrying to the different diseases that they are addressing. One area that's been pervasive within CAR-T is whether you can deliver in vivo material that will directly infect T-cells and not have to go through an ex vivo CAR-T treatment. We've heard a lot of progress being made in that area so that's clearly exciting for the field.

Another area that's been important is in vivo gene editing, and we've seen some some great progress being done in that area with good safety measures. So gene editing in the in vivo setting is clearly becoming the next frontier that investigators are taking on and I think we're seeing some early results that are quite encouraging, and importantly, safe.

This transcript has been edited for clarity.

Click here to view more coverage of the 2025 ASGCT Annual Meeting.