Gilead's Strategic Move into In Vivo CAR-T: A Game-Changer in Cell Therapy?

In the ever-evolving landscape of biopharmaceutical innovation, Gilead Sciences' $350 million acquisition of Interius BioTherapeutics in August 2025 has ignited a firestorm of speculation about the future of cell therapy. This move, which brings Interius's proprietary in vivo CAR-T platform under Kite Pharma's umbrella, marks Gilead's most aggressive foray yet into a sector poised for explosive growth. But is this acquisition a transformative leap forward—or a high-stakes gamble?

The In Vivo Revolution: A Paradigm Shift in CAR-T

Traditional CAR-T therapies, such as Kite's Yescarta and Tecartus, rely on ex vivo processes: harvesting a patient's T cells, engineering them to target cancer, and reinfusing them. This approach, while groundbreaking, is plagued by high costs, logistical complexity, and limited scalability. In contrast, in vivo CAR-T bypasses these hurdles by delivering genetic material directly into the patient's body via vectors like lipid nanoparticles (LNPs) or viral vectors. This eliminates the need for cell harvesting and reinfusion, reducing treatment timelines from weeks to days and slashing costs.

Interius's platform, now integrated into Kite's R&D infrastructure, exemplifies this shift. Its lead candidate, INT2104, is already in Phase I trials for B-cell malignancies, demonstrating the feasibility of in vivo approaches. The modular design of Interius's technology allows rapid adaptation to different disease targets, positioning Gilead to expand into hematological cancers, solid tumors, and even autoimmune disorders.

Market Dynamics: A $32.9% CAGR Opportunity

The in vivo CAR-T market is projected to grow at a compound annual growth rate (CAGR) of 32.9% from 2025 to 2034, driven by advancements in delivery systems and unmet medical needs. Key enablers include:
- Lipid Nanoparticles (LNPs): Accounting for 42% of the in vivo CAR-T market in 2024, LNPs offer stability, scalability, and reduced manufacturing complexity.
- Viral Vectors: Lentiviral and adeno-associated viral (AAV) vectors remain dominant for their high transfection efficiency and regulatory familiarity.
- Global Demand: Hematological cancers, particularly B-cell malignancies, represent the fastest-growing segment, fueled by the success of early-stage therapies and rising incidence rates.

North America, with its robust R&D infrastructure and favorable regulatory environment, leads the market. However, China's aggressive investment in cell therapy—evidenced by 508 clinical trials registered on ClinicalTrials.gov as of July 2025—signals a rapidly closing gap.

Competitive Landscape: Gilead's Position in a Crowded Field

Gilead is not alone in its pursuit of in vivo CAR-T dominance. Major players like AbbVie (acquiring Capstan Therapeutics for $2.1 billion) and AstraZeneca (via its EsoBiotec acquisition) are also staking claims. Yet Gilead's strategy stands out: by vertically integrating Interius's platform, it avoids the pitfalls of external partnerships and leverages Kite's global manufacturing network to accelerate development.

The acquisition also aligns with broader industry trends. For instance, the rise of mRNA-encoded CARs—now dominating 48% of the market in 2024—highlights the sector's shift toward safer, more scalable payloads. Gilead's investment in LNPs and modular platforms positions it to capitalize on these trends while mitigating risks associated with single-technology bets.

Financial Implications: Short-Term Pain for Long-Term Gain

While the Interius acquisition is expected to reduce Gilead's 2025 GAAP and non-GAAP EPS by $0.23–$0.25, this is a calculated trade-off. The in vivo CAR-T market's projected $32.9% CAGR suggests that early movers like Gilead could see outsized returns by 2034. Moreover, the acquisition complements Gilead's existing cell therapy portfolio, creating a dual-track strategy that balances near-term revenue from ex vivo therapies with long-term growth from in vivo innovations.

Risks and Realities: Navigating the Hurdles

Despite the optimism, challenges remain. In vivo CAR-T therapies must overcome safety concerns, including off-target effects and long-term genomic stability. Clinical trial data for INT2104 and other candidates will be critical in proving efficacy and securing regulatory approvals. Additionally, reimbursement models for in vivo therapies are still evolving, with payers likely to demand robust cost-benefit evidence.

Investment Thesis: A High-Conviction Play

For investors, Gilead's acquisition of Interius represents a high-conviction opportunity in a high-growth sector. The company's vertical integration, combined with its track record in cell therapy (e.g., Yescarta's commercial success), provides a strong foundation for scaling in vivo technologies. However, patience is key: the path to profitability will depend on clinical milestones and regulatory approvals over the next 3–5 years.

Recommendations for Investors:
1. Long-Term Holders: Position in Gilead for its dual-track strategy, balancing near-term ex vivo revenue with in vivo growth.
2. Sector Diversification: Consider complementary plays like AbbVie or AstraZeneca, which are also investing heavily in in vivo platforms.
3. Risk Mitigation: Monitor clinical trial updates for INT2104 and other in vivo candidates, as data will drive valuation multiples.

In conclusion, Gilead's foray into in vivo CAR-T is not just a strategic move—it's a bold bet on the future of medicine. While the road ahead is fraught with challenges, the potential rewards for early adopters are immense. As the sector matures, those who recognize the transformative power of in vivo technologies today may reap the benefits for decades to come.