Advanced Therapies Week 2025: In Vivo Therapeutics

At Advanced Therapies Week 2025, the video transcript covers an in-depth panel discussion and presentations focused on the future of CAR-T cell immunotherapy (CTI), particularly emphasizing the evolution from autologous ex vivo manufacturing toward in vivo CAR-T generation. The experts, Ulf Grawunder, Cécile Bauché, and Bruce L. Levine, explore current challenges, emerging technologies, and prospective solutions in the CTI field. The discussion begins by outlining the tremendous clinical successes of autologous CAR-T therapies but highlights their limited patient reach due to complex, costly, and centralized manufacturing processes involving lentiviral and retroviral vectors. The speakers emphasize the urgent need to overcome these bottlenecks to treat the expanding patient population, including those with solid tumors, autoimmune diseases, and genetic disorders.

The conversation transitions into the promise of in vivo CAR-T cell generation, where vectors or nanoparticles are directly administered to patients to induce CAR-T cells inside the body, thereby bypassing complex ex vivo manufacturing steps. The panelists detail different delivery systems, including lentiviral vectors, adeno-associated viruses (AAV), mRNA lipid nanoparticles (LNPs), and polymer-coated lentiviral vectors, discussing their advantages and potential safety concerns such as off-target effects, immunogenicity, and vector biodistribution.

Cécile Bauché presents an innovative hybrid polymer-coated lentiviral vector system designed to enhance targeting specificity, reduce liver uptake, and preserve T cell phenotypes to improve persistence and efficacy. This system offers flexibility for both in vivo and ex vivo or translational applications, with promising preclinical data in immunocompetent animal models showing CAR expression, tumor killing, and low toxicity without lymphodepletion.

Bruce L. Levine presents pioneering work using targeted mRNA LNPs for transient CAR expression, particularly in autoimmune and fibrotic diseases. He highlights advances in improving nanoparticle biodistribution, reducing liver toxicity, and enabling repeat dosing to reset pathogenic immune responses. Data from non-human primate studies demonstrate efficient T cell targeting, B cell depletion, and rapid on-target effects.

Throughout the discussion, the experts address major safety challenges, such as the risk of CAR expression on tumor cells themselves potentially leading to “super leukemia,” immunogenicity limiting repeat dosing, and the need for safety switches. They advocate for a stepwise evolution including decentralized point-of-care manufacturing and extracorporeal transduction approaches as intermediate steps toward fully in vivo therapies. The panel concludes that while in vivo CAR-T therapies are still nascent, they hold transformative potential to make cell therapies more accessible, affordable, and scalable within the next decade. Multiple platforms and manufacturing strategies are expected to coexist, with therapy choices personalized to patient needs and disease indications.

Highlights

• Autologous CAR-T therapies have remarkable efficacy but treat less than 10% of eligible patients due to manufacturing bottlenecks.
• In vivo CAR-T generation promises to eliminate complex ex vivo manufacturing by directly delivering vectors or nanoparticles to patients.
• Hybrid polymer-coated lentiviral vectors can target T cells specifically, avoid liver uptake, and enable durable CAR expression with low toxicity.
• mRNA lipid nanoparticles enable transient CAR expression, are safer for repeat dosing, and show promise in autoimmune and fibrotic disease models.
• Major safety concerns include off-target effects, immunogenicity, and the risk of CAR signaling in malignant cells, requiring safety switches and rigorous testing.
• Decentralized point-of-care and extracorporeal manufacturing may serve as transitional solutions bridging ex vivo and in vivo approaches.
• The future of CAR-T therapies will feature multiple coexisting technologies tailored to diverse indications, with a goal to expand global patient access and reduce costs.

Key Insights

• Efficacy vs. Accessibility Tradeoff in Autologous CAR-T: Although autologous CAR-T therapies have demonstrated near-complete response rates in hematologic malignancies, their high cost (about $400,000 per treatment) and centralized manufacturing limit patient access to fewer than 10% of eligible patients globally. The complexity of GMP-grade vector production, cleanroom facilities, and specialized personnel creates logistical bottlenecks and supply shortages, especially in viral vector availability. This insight underscores the pressing need for alternative manufacturing paradigms to scale treatment to millions of patients, including those with solid tumors and autoimmune diseases.
• In Vivo CAR-T Generation as a Paradigm Shift: Direct in vivo generation of CAR-T cells via systemic administration of viral or nonviral vectors eliminates the need for leukapheresis, ex vivo cell manipulation, and lengthy manufacturing. This approach could democratize access by reducing costs, simplifying supply chains, and enabling rapid treatment cycles without lymphodepletion. However, translating this concept from murine and non-human primate models to humans poses challenges related to delivery efficiency, immune system variability, and safety. This insight highlights the transformative potential of in vivo approaches while acknowledging the technical hurdles ahead.
• Safety Challenges in In Vivo CAR-T Approaches: Precise targeting of T cells is critical to avoid off-target transduction of hepatocytes or other non-immune cells, which can cause toxicity and reduce therapeutic efficacy. Furthermore, inadvertent transduction of malignant B cells may create hyperactive tumor cells, increasing relapse or secondary malignancy risk. Immunogenicity against vector components limits repeat dosing, necessitating the development of biodegradable carriers, immune-silent delivery systems, and safety switches to mitigate these risks. The safety profile remains a paramount consideration guiding clinical translation.
• Innovative Hybrid Polymer-Coated Lentiviral Vectors: The technology presented by Cécile Bauché integrates lentiviral vectors with a polymer coating that restores transduction ability, shields vectors from liver uptake, and allows modular attachment of targeting ligands. This design preserves desirable T cell phenotypes, potentially enhancing persistence and antitumor activity. Preclinical studies demonstrate robust CAR expression, tumor killing, and excellent safety in immunocompetent models without lymphodepletion. This platform’s flexibility for both in vivo and ex vivo use offers a practical path toward clinical translation.
• Targeted mRNA Lipid Nanoparticles for Transient CAR Expression: Bruce L. Levine’s work leverages mRNA LNPs targeted to T cells to induce transient CAR expression, which is advantageous for diseases where permanent CAR-T cells are undesirable, such as fibrosis or autoimmunity. Improved LNP formulations reduce liver targeting and toxicity, enabling multiple repeat doses and fine-tuned immune modulation. Data from non-human primates show effective T cell targeting and B cell depletion, supporting clinical exploration.
• Point-of-Care and Extracorporeal Manufacturing as Transitional Strategies: The panelists emphasize that a direct leap from centralized ex vivo manufacturing to fully in vivo approaches may be premature due to safety concerns and regulatory hurdles. Intermediate solutions, like bedside manufacturing or extracorporeal transduction devices, offer the benefits of decentralization and control while reducing complexity and cost. These strategies can bridge current technology gaps and gradually introduce patients to more accessible therapies.
• Future Landscape: Coexistence and Personalization: The experts anticipate that no single technology will dominate soon. Multiple platforms, autologous, allogeneic, point-of-care, in vivo, viral, and nonviral, will coexist, with selection based on indication, patient characteristics, safety profiles, and cost. Advances in manufacturing, vector engineering, and immunology will enable increasingly personalized therapies, optimized for efficacy and safety.

Extended Analysis
The discussion at Advanced Therapies Week 2025 elucidates constraints of current CAR-T treatments, where centralized, ex vivo manufacturing throttles capacity, inflates costs, and restricts access. In vivo CAR-T cell generation emerges as a disruptive paradigm by turning the patient’s body into a bioreactor. The panel describes two main vector modalities, viral vectors such as lentivirus and AAV, and nonviral systems such as mRNA LNPs and polymeric nanoparticles, each with distinct advantages and challenges.

A notable innovation is the hybrid polymer-coated lentiviral vector technology, which combines the integrating power of lentivirus with targeting flexibility of polymeric nanoparticles. By limiting nonspecific liver tropism and enabling T cell targeting, this platform addresses obstacles of off-target transduction while preserving naïve and memory T cell phenotypes crucial for persistence.

Bruce L. Levine’s work with targeted mRNA LNPs shows how transient CAR expression can be harnessed for indications beyond oncology. Refined formulations minimize liver uptake and toxicity, enabling safe repeat dosing, a step forward for chronic indications.

Safety remains the overarching concern. Risks such as inadvertent CAR expression on tumor cells, immunogenicity to delivery components, and biodistribution uncertainties require engineered safety switches and careful preclinical validation. The experts advocate a gradual transition in manufacturing philosophy, from centralized production to point-of-care and extracorporeal systems, culminating in fully in vivo therapies as evidence and safeguards mature.

Finally, the panel agrees that the future of CAR-T and cell therapies will be pluralistic. As costs decline and technologies mature, cell therapies are poised to become more accessible worldwide, moving from niche, high-cost interventions to broadly available medicines.

Conclusion
This Advanced Therapies Week 2025 session charts the pathway from today’s ex vivo CAR-T manufacturing to tomorrow’s in vivo therapeutics. With advances in delivery science, safety engineering, and point-of-care platforms, the field is moving toward scalable, repeatable treatments that broaden global access while maintaining efficacy and safety.