INTERVIEW QUESTIONS

1. In vivo CAR-T is emerging as one of the most promising advancements in cell and gene therapy. What is driving this momentum, and how does it differ from the traditional ex vivo CAR-T approach?

One of the biggest drivers is the potential to make CAR-T therapy more accessible. Traditional ex vivo CAR-T has produced remarkable clinical results, but it’s also an individualized process. Cells are collected from each patient, engineered outside the body, tested, and then returned to the patient. It’s complex, time intensive, and requires highly coordinated manufacturing.

In vivo CAR-T takes a different approach. Rather than modifying cells outside the body, the viral vector is delivered directly to the patient, where it engineers the target cells in vivo. If developers can do that safely and consistently, it has the potential to simplify manufacturing, reduce treatment timelines, and expand patient access.

The shift to in vivo also changes where much of the scientific focus lies. Instead of concentrating primarily on the engineered cells, developers need to fully understand the viral vector itself, how it performs, how it’s characterized, and how its quality and safety is demonstrated before it’s delivered to the patient.

2. How are the differences between in vivo and ex vivo CAR-T therapies reshaping analytical testing requirements throughout product development?

The biggest change is what you are actually testing. With ex vivo CAR-T, much of the analytical work focuses on the engineered cell product. With in vivo CAR-T, the viral vector becomes the therapeutic product, so your analytical strategy shifts accordingly. You’re putting much greater emphasis on understanding the vector’s identity, potency, purity, safety, infectious titer, and overall performance.

We’ve supported lentiviral vector testing for many years at Minaris Advanced Testing, through ex vivo CAR-T and other gene therapy programs, so many of the scientific principles remain familiar. We’ve also supported testing for in vivo LVV CAR-T and what’s different is the level of understanding required before that vector is administered directly to a patient.

That means developers need analytical strategies that are tailored to their specific product rather than relying on generic testing approaches. It’s not simply a matter of checking regulatory boxes. The testing has to generate data that accurately reflects how that product is expected to perform.

3. What unique analytical and safety challenges does the direct delivery of lentiviral vectors present in in vivo CAR-T therapies compared to conventional gene therapy products?

Direct delivery raises the bar for understanding the vector because the vector itself is responsible for finding the right target cells and driving the intended biological response inside the patient.

From an analytical perspective, that places even greater importance on demonstrating safety, consistency, and functionality. Assays such as infectious titer and replication-competent lentivirus testing become especially important, but they do not tell the whole story. You also need robust identity testing, potency assays, impurity testing, and product characterization to understand whether you’re consistently producing the product you intended to make.

The challenge is that these vectors are not all designed the same way. Differences in construct design, targeting strategy, and mechanism of action often mean that analytical methods need to be customized. That’s why a thoughtful, product-specific testing strategy is so important from the earliest stages of development.

4. What critical quality attributes should developers prioritize when designing analytical testing strategies for in vivo lentiviral CAR-T products?

Honestly, there is not one attribute that’s more important than the others because each one answers a different question about the product. Identity confirms you’ve made the correct vector. Potency demonstrates biological activity. Purity evaluates process-related impurities, while sterility, mycoplasma, endotoxin, and replication-competent lentivirus testing help establish microbiological safety. Stability studies demonstrate that the product maintains those characteristics over time.

What regulators ultimately want to see is a complete picture of product quality. No single assay can provide that on its own. That’s why we encourage developers to think about these assays as an integrated testing strategy rather than a collection of individual tests. When all of those data come together, they provide confidence that the product is safe, consistent, and suitable for clinical use.

5. Replication-Competent Lentivirus (RCL) and infectious titer testing are considered essential for in vivo CAR-T products. Why are these assays so critical, and why do they often require product-specific customization?

These assays are foundational because they address two of the most important questions developers need to answer before releasing a product. Replication-competent lentivirus testing helps demonstrate that the vector cannot replicate in a way that could create an unintended safety risk. Infectious titer measures the functional concentration of the vector, which directly influences dose selection and product consistency. Both are critical from both a patient safety and regulatory perspective.

Where it becomes more challenging is that lentiviral vectors aren’t interchangeable. Different vector designs, transgenes, and targeting strategies can influence how an assay performs. We’ve found that a standardized approach often isn’t enough for these programs.

Developing assays that are fit for the specific product produces more meaningful data and helps sponsors make better decisions as programs move through clinical development and toward commercialization.

6. Potency assays for in vivo CAR-T therapies frequently need to be tailored to individual products. What factors drive this customization, and what should an effective potency assay demonstrate?

Potency is one of the most challenging aspects of analytical development because it isn’t a one-size-fits-all measurement. The right assay depends on how a particular therapy is designed to work.

With in vivo CAR-T, you’re evaluating a viral vector that’s expected to deliver its genetic payload, generate CAR expression, and ultimately trigger the intended biological response inside the patient. Different vectors use different constructs, promoters, and targeting strategies, so a generic potency assay often won’t tell the full story.

An effective potency assay should reflect the product’s mechanism of action as closely as possible. Whether that’s measuring transduction efficiency, CAR expression, downstream signaling, or a functional cell-based response, the goal is to generate data that’s scientifically meaningful and supports both product development and regulatory expectations.

7. How do identity, potency, purity, sterility, mycoplasma, endotoxin, and product characterization testing collectively contribute to ensuring product quality, patient safety, and regulatory compliance?

I like to view these assays as pieces of a puzzle. Each one answers a different question, but none of them are sufficient on their own.

Identity confirms you’re releasing the correct product. Potency tells you whether it’s performing as intended. Purity evaluates residual process-related materials, while sterility, mycoplasma, and endotoxin testing address microbiological safety. Product characterization helps demonstrate that the vector consistently meets its expected quality attributes.

When you put all of that information together, you build a comprehensive understanding of the product. That’s what gives developers confidence in each lot, and it’s ultimately what regulators are looking for as therapies progress through clinical development and into commercialization.

8. What are the key differences in analytical testing requirements between drug substance and drug product, and why is it important to establish robust lot release strategies for both?

Drug substance and drug product represent different points in the manufacturing process, so the objectives of testing are different.

Drug substance testing is focused on confirming that the vector has been manufactured correctly before formulation. You’re looking closely at attributes like identity, potency, purity, safety, and infectious titer to understand the quality of the material being produced.

Drug product testing confirms that those same critical quality attributes have been maintained after formulation and filling. It also introduces additional considerations such as container integrity, appearance, fill volume, and stability.

One mistake we sometimes see is treating lot release as something to figure out later. In reality, establishing that strategy early makes the entire development process more efficient. It helps ensure analytical methods evolve alongside the product instead of becoming a bottleneck as programs move toward clinical studies or commercialization.

9. The importance of analytical planning early in development is increasingly being emphasized. Why should sponsors establish their analytical strategy and lot release testing plan as early as possible?

Analytical development tends to become much more difficult when it’s reactive. If you are building your testing strategy early, you have the opportunity to develop assays that truly fit the product and generate data that will remain useful as the program matures. If you wait until later, you’re often trying to retrofit methods to support regulatory submissions or commercial manufacturing, and that’s usually more time consuming and more expensive.

We’ve found that early planning also creates better alignment between manufacturing, analytical development, and quality. This includes evaluating the volumes required for all tests, to ensure that sufficient material is available for both testing and treating patients. Everyone is working toward the same quality goals from the beginning, which reduces surprises later and creates a smoother path through clinical development and commercialization.

10. As regulatory expectations continue to evolve for in vivo CAR-T therapies, what should developers consider when developing, qualifying, and validating analytical methods to support global submissions?

The first consideration is making sure the methods are appropriate for where the program is today while keeping an eye on where it’s going next.

Early-stage methods don’t necessarily need to look exactly like commercial release methods, but they should be built with a clear path toward qualification and validation. That makes it much easier to transition through clinical development without having to redesign your analytical strategy along the way.

It’s also important to recognize that regulatory expectations continue to evolve as new therapies emerge. Developers should focus on building methods that are scientifically sound, reproducible, and capable of generating meaningful data that supports product quality. When those fundamentals are in place, you’re in a much stronger position to support submissions across multiple regulatory agencies and avoid unnecessary delays later in development.

11. How does stability testing contribute to demonstrating the quality and shelf life of in vivo lentiviral CAR-T products, and what challenges do developers commonly face in this area?

Stability testing is often thought of as simply determining an expiration date, but it plays a much bigger role than that. It tells you whether the product continues to maintain the characteristics that matter most over time, including potency, safety, and overall quality.

For lentiviral vectors, that can be particularly challenging because these are complex biological products. Factors like storage conditions, formulation, and handling can all influence product performance. You need stability data that reflects how the product will actually be stored, transported, and used throughout its lifecycle.

The earlier developers begin building a thoughtful stability strategy, the easier it is to generate the data needed to support clinical development and commercialization.

12. Given the complexity of these therapies, how important is product-specific assay development in generating reliable data and meeting regulatory expectations across different stages of development?

It is becoming increasingly important because these products simply are not interchangeable. Each lentiviral vector has its own design, mechanism of action, and biological characteristics, so the analytical approach needs to reflect those differences.

A customized assay is more likely to generate data that’s truly representative of how the product performs, rather than forcing the product to fit an existing method that wasn’t designed for it.

That doesn’t mean every assay has to be built from scratch, but developers should be prepared to adapt and optimize methods where appropriate. In our experience, investing that effort early leads to stronger data, smoother regulatory interactions, and fewer surprises as programs advance.

13. How can integrated analytical services spanning method development, qualification, validation, and GMP-compliant lot release testing help accelerate the development and commercialization of in vivo CAR-T therapies?

One advantage of an integrated approach is continuity. When the same scientific team supports analytical development through GMP lot release, there’s a much deeper understanding of the product and the rationale behind each method. That reduces knowledge transfer challenges and helps maintain consistency as programs move from one stage of development to the next.

For sponsors, it also simplifies project management. Instead of coordinating multiple testing providers, they have one team that understands the product, the analytical strategy, and the regulatory expectations from beginning to end.

Ultimately, the goal isn’t just to complete individual assays. It’s to generate a consistent body of data that supports development, regulatory submissions, and commercial manufacturing without creating unnecessary complexity along the way.

14. How has Minaris Advanced Testing’s experience supporting lentiviral vector and ex vivo CAR-T programs prepared the organization to support the next generation of in vivo CAR-T therapies?

In vivo CAR-T introduces new scientific questions, but it also builds on many of the lessons the industry has learned from lentiviral vector and ex vivo CAR-T development over the past several years.

We’ve supported lentiviral vector testing and commercial-stage cell and gene therapy programs across multiple stages of development, so we’ve seen firsthand how analytical requirements evolve as products move closer to patients. That experience provides a strong foundation for supporting in vivo approaches, even though the analytical strategies continue to evolve.

What’s changing is not our commitment to rigorous science. It’s how we apply that experience to new therapeutic approaches. As in vivo CAR-T continues to mature, we’re building on decades of analytical and biosafety expertise while expanding our capabilities to address the unique challenges these products present.

15. Looking ahead, what advances in lentiviral vector testing do you believe will have the greatest impact on enabling the safe and successful commercialization of in vivo CAR-T therapies?

I think we will continue to see testing become more precise and more closely aligned with how these products actually work. That includes more sophisticated potency assays, broader product characterization, and analytical methods that provide deeper insight into vector performance rather than simply confirming that a specification has been met. We’ll also continue to see advances in technologies that improve sensitivity, reproducibility, and the ability to detect potential safety concerns earlier.

More broadly, I think the industry is recognizing that analytical testing isn’t just a regulatory requirement. It’s a critical part of product development. The better we become at understanding these therapies through robust analytical science, the better positioned we’ll be to bring safe, effective treatments to more patients.

As exciting as the science is, success will ultimately depend on consistency. The therapies have to be manufactured reliably, tested rigorously, and supported by data that gives developers, regulators, clinicians, and patients confidence. That’s where analytical science has an opportunity to make a real difference.