Gilead's Strategic Move into In Vivo CAR-T Therapies: Evaluating the Long-Term Value of In Vivo Platforms in Redefining the CAR-T Market

The in vivo CAR-T therapy market is poised to redefine the landscape of oncology and immunotherapy, with a projected 32.9% compound annual growth rate (CAGR) from 2025 to 2034. As traditional ex vivo CAR-T therapies face scalability and cost challenges, in vivo platforms—where T cells are engineered directly within the patient's body—are emerging as a transformative solution. Gilead Sciences, through its Kite Pharma subsidiary, has made a bold strategic pivot into this space with the $350 million acquisition of Interius BioTherapeutics in 2025. This move positions Gilead to capitalize on a market that could grow into a multibillion-dollar opportunity while addressing critical unmet needs in cancer treatment.

The In Vivo CAR-T Revolution: A Market in Motion

The in vivo CAR-T market is driven by advancements in delivery systems like lipid nanoparticles (LNPs), which dominated 42% of the market in 2024. These technologies enable the direct modification of T cells in vivo, eliminating the need for complex ex vivo manufacturing. This approach reduces treatment timelines, lowers costs, and improves accessibility—key advantages in a market where ex vivo therapies like Yescarta and Tecartus face declining sales due to high prices and logistical hurdles.

North America, with its 61% market share in 2024, remains the epicenter of innovation, but Asia-Pacific is surging as a growth engine. Countries like China and Japan are accelerating clinical trials and regulatory approvals, with China alone approving six CAR-T therapies for nine indications by 2025. Gilead's acquisition of Interius, a company with a modular in vivo platform and a lead candidate (INT2104) in Phase I trials for B-cell malignancies, aligns with this global shift.

Gilead's Strategic Positioning: A Leap Beyond Ex Vivo

Gilead's Kite division has long dominated the ex vivo CAR-T market, but its recent foray into in vivo therapies reflects a calculated response to industry challenges. By acquiring Interius, Gilead gains access to a platform that uses engineered viruses to deliver genetic instructions directly to immune cells, bypassing the need for preconditioning chemotherapy and complex cell handling. This “off-the-shelf yet personalized” model could democratize access to CAR-T therapies, particularly in resource-limited settings.

Compared to peers like AstraZeneca and AbbVie, Gilead's vertically integrated approach offers a distinct advantage. While AstraZeneca partners with EsoBiotec and AbbVie collaborates with Umoja Biopharma, Gilead has embedded in vivo expertise directly into its R&D infrastructure. This strategy accelerates development timelines and reduces dependency on external partners, a critical factor in a race to secure regulatory approvals and market share.

Navigating Regulatory and Financial Risks

Despite its strategic advantages, Gilead faces significant hurdles. The U.S. FDA has placed clinical holds on some of Gilead's HIV trials, underscoring the agency's cautious stance on novel therapies. For in vivo CAR-T, regulatory approval will hinge on demonstrating safety, particularly around off-target effects and long-term genomic stability. Gilead's experience with ex vivo therapies provides a foundation for addressing these concerns, but the in vivo paradigm introduces new complexities.

Financially, the acquisition is expected to reduce Gilead's 2025 earnings per share by $0.23–$0.25. However, this short-term hit is a calculated trade-off for long-term gains. The in vivo CAR-T market is projected to reach hundreds of millions in revenue by 2034, and Gilead's early mover status could secure a dominant position. Additionally, the company's $28.3–28.7 billion 2025 revenue guidance reflects confidence in its diversified pipeline, including oncology and HIV treatments.

Investment Implications: A High-Stakes Bet on Innovation

For investors, Gilead's in vivo strategy represents a high-risk, high-reward opportunity. The company's ability to scale Interius' platform and generate positive Phase I data for INT2104 will be critical milestones. If successful, Gilead could not only reverse declining sales in its ex vivo portfolio but also establish a new revenue stream in a market with minimal competition.

However, the path to profitability is not without risks. Solid tumor indications, where in vivo CAR-T holds promise, remain a clinical challenge. Gilead's collaboration with Arcellx on anitocel for multiple myeloma highlights its efforts to diversify, but results will need to outperform peers to justify the investment.

Conclusion: A Pioneering Move in a Transformative Era

Gilead's acquisition of Interius is a masterstroke in a rapidly evolving market. By leveraging its R&D infrastructure and manufacturing scale, the company is well-positioned to lead the in vivo CAR-T revolution. While regulatory and financial risks persist, the long-term potential of this platform—coupled with Gilead's track record in oncology—makes it a compelling investment for those willing to bet on innovation. As the in vivo CAR-T market matures, Gilead's strategic foresight could redefine not only its own trajectory but the future of cancer treatment itself.

For investors, the key takeaway is clear: Gilead's in vivo pivot is not just a response to market pressures—it's a visionary leap into the next frontier of biotech. The coming years will determine whether this bold move pays off, but the stakes have never been higher.