Inside AbbVie's $2.1 Billion Bet on In Vivo CAR-T

Why AbbVie paid $2.1 billion for a therapy with no published human data

Prepared by Richstorm.co

Key Takeaways

• In vivo CAR-T is designed to reduce the manufacturing and access barriers of conventional CAR-T. Its different pharmacology may also change efficacy, durability, and safety.

• AbbVie acquired an early clinical asset. For accounting purposes, substantially all of the fair value of the acquired gross assets was concentrated in the lead program.

• The central unanswered question is whether a short period of CAR activity without lymphodepletion can produce the kind of durable, drug-free remission observed after conventional CAR-T.

1. The $2.1 billion question

On June 30, 2025, AbbVie announced that it would acquire Capstan Therapeutics. The deal closed on August 19. AbbVie's third quarter 2025 Form 10-Q reports cash consideration of $2.1 billion, or $1.9 billion net of cash acquired. It also reports $187 million of post-closing expense for Capstan employee incentive and compensation awards.

Capstan's lead product, CPTX2309, had just entered a Phase 1 trial in healthy volunteers in Australia. AbbVie announced the acquisition 19 days after Capstan publicly said that dosing had begun.

As of the June 30 acquisition announcement, no human data for CPTX2309 had been made public. Clinical evidence across the wider in vivo CAR-T field was also limited. What, then, was AbbVie paying for?

Public filings do not provide the asset-level revenue forecasts or probability-of-success assumptions needed for a credible valuation. This article therefore focuses on more answerable questions: what AbbVie acquired, how far the evidence has progressed, and which assumptions still carry the most risk.

2. What limits CAR-T today

Conventional autologous CAR-T starts with a patient's own T cells. The cells are collected, engineered to recognize a marker on selected target cells, expanded, tested, and returned to the patient. This approach has produced strong clinical results in several blood cancers.

The process is also difficult to scale. Every autologous dose is made for one patient. Cells must travel to and from a specialized facility, and the patient typically receives lymphodepleting chemotherapy before infusion. A 2026 review in the Journal of Biological Engineering summarizes typical reported costs of €300,000 to €500,000 per treatment in Europe and the United States, with three to six weeks from cell collection to infusion. An expert cited by AJMC estimated that only 10% to 20% of eligible multiple myeloma patients ultimately receive CAR-T, although this was not a systematic survey.

Conventional CAR-T also faces relapse, antigen escape, limited durability in some patients, and serious immune toxicities. In vivo CAR-T most directly addresses manufacturing and access. Whether it improves or worsens the other problems remains unproven and may depend on the delivery platform.

3. What in vivo CAR-T changes

Capstan is a University of Pennsylvania spinout that raised a $175 million Series B in 2024. Its approach moves the T-cell engineering step out of the manufacturing facility and into the patient.

CPTX2309 uses two layers of targeting. First, an antibody on the surface of a lipid nanoparticle directs the particle preferentially to cells that express CD8, especially cytotoxic T cells. The particle delivers mRNA that instructs those T cells to temporarily express an anti-CD19 chimeric antigen receptor. CD19 is found on B cells. The newly generated CAR-T cells can therefore recognize and kill B cells in blood and tissue.

The distinction is important. The nanoparticle targets the T cell that will be reprogrammed. The CAR made by that T cell then targets the B cell that will be removed.

This approach could change the commercial model. It does not require apheresis or individualized cell manufacturing. It also avoids viral vectors and genomic integration, and it is designed to work without lymphodepleting chemotherapy. In principle, it could turn CAR-T from a patient-specific manufacturing service into something closer to a standardized injectable product. Whether it can deliver consistent clinical results at scale remains unknown.

Preclinical work supports the mechanism. In non-human primates, CAR expression reached roughly 85% of CD8-positive T cells. A low dose completely depleted B cells from peripheral blood within hours, and B-cell recovery began within two to three weeks. Most of the returning cells were naïve B cells. The same study also found CAR expression in CD8-positive natural killer cells and monocytes, which means the targeting was preferential rather than exclusive. These results come from a company-sponsored conference abstract, not a full peer-reviewed paper.

The intended result is an immune reset that may allow patients to remain in remission without indefinite immunosuppressive treatment.

4. Why autoimmune disease first

Blood cancer may seem like the obvious starting point because CAR-T is already established there. But Capstan’s temporary mRNA approach may be better matched to the treatment goal in autoimmune disease.

In cancer, CAR-T cells may need to remain active long enough to eliminate residual malignant cells and prevent regrowth. In autoimmune disease, the goal may be different. A temporary treatment could remove the B cells that sustain the abnormal immune response, then stop once that task is complete. If a healthier B-cell population later rebuilds, a short period of CAR activity might be enough to produce an immune reset.

A 2024 New England Journal of Medicine case series provided clinical support for targeting B cells in this way. Fifteen patients with severe autoimmune disease received conventional CD19 CAR-T. During a median follow-up of 15 months, all stopped immunosuppressive treatment, and all eight lupus patients met formal remission criteria.

The study therefore supported the target and the disease strategy. It showed that deep CD19-directed B-cell depletion can be followed by drug-free remission. It did not validate Capstan’s specific treatment design, because the patients received conventional CAR-T after lymphodepleting chemotherapy. Whether a temporary in vivo approach can produce the same result is a separate question.

5. The most important unproven assumption

However, the remission observed in that case series followed a treatment very different from ABBV-619. All 15 patients received fludarabine and cyclophosphamide before CAR-T infusion, and B-cell aplasia lasted a mean of 112 days. The study therefore supported the immune-reset strategy, but not Capstan’s shorter and less intensive method of achieving it.

ABBV-619 generates CAR-T cells inside the patient, removing the need to collect and engineer each patient’s cells in a manufacturing facility. It is also designed to work without lymphodepleting chemotherapy and uses mRNA, so CAR expression is temporary. Avoiding patient-specific manufacturing creates the potential for scale. Temporary CAR expression may improve control and safety, but it also raises questions about how long the treatment effect will last.

Early clinical data from HN2301 show that a similar temporary approach can produce biological activity in humans. HN2301 is not the same product as ABBV-619, but it also uses a CD8-targeted lipid nanoparticle to deliver CD19 CAR mRNA without lymphodepletion. In five patients with refractory lupus, the treatment generated CAR-T cells and reduced disease activity at three months. In the three patients who received the higher dose, circulating B cells were completely depleted for about seven to ten days.

The central unanswered question is whether such a brief period of CAR activity and B-cell depletion can produce lasting, drug-free remission. The 112 days reported with conventional CAR-T and the seven to ten days reported with HN2301 cannot be compared directly because the studies used different products, patients, pretreatments, and measurements. The evidence does not prove that prolonged B-cell depletion is necessary. It shows that the biological exposure is very different. HN2301 has demonstrated short-term activity, but neither HN2301 nor ABBV-619 has yet shown that a temporary in vivo mRNA treatment can reproduce the durable remission observed after conventional CAR-T.

6. Why AbbVie specifically

Three factors may help explain why AbbVie was the buyer.

An established immunology business. Skyrizi and Rinvoq together accounted for roughly 42% of AbbVie's total net revenues in 2025. AbbVie already has autoimmune drug development capabilities, clinical trial networks, and commercial channels. ABBV-619 can enter an existing organization rather than requiring a new one to be built around it.

An asset with a qualified platform story. AbbVie's acquisition announcement covered Capstan's delivery technology and preclinical programs as well as the lead asset. The platform is designed to carry different RNA payloads. However, AbbVie accounted for the transaction as an asset acquisition rather than a business combination because the lead program represented substantially all of the fair value of the gross assets acquired. This limits the claim that the recorded acquisition value was spread broadly across a mature platform. It does not rule out value from future platform applications.

Time in exchange for control. Waiting for patient efficacy data would have reduced scientific uncertainty. It might also have increased competition and price. Buying early gave AbbVie control of the asset while accepting greater development risk. This is an inference from the timing, not a rationale disclosed by AbbVie.

7. What the deal wave tells us

These transactions are not directly comparable. Their structures, delivery technologies, and indications differ. The Johnson & Johnson agreement, for example, is a collaboration, equity investment, and acquisition option rather than a completed acquisition. The table therefore does not establish a valuation trend.

What it does show is that several large pharmaceutical companies were willing to acquire companies or secure broad rights to in vivo cell-engineering technologies while clinical evidence was still limited. This supports the strategic importance of the field, but it does not reduce the product-specific risk facing ABBV-619. The value of AbbVie's acquisition will still depend on whether its particular approach can produce durable benefit at a safety standard appropriate for autoimmune disease.

8. What to watch next

Three signals now matter most: the depth and duration of B-cell depletion in lupus and rheumatoid arthritis, the safety and immunogenicity of repeat dosing, and whether patients remain in remission after stopping treatment.

The strategic logic of the acquisition is clear. AbbVie bought early access to a potentially more scalable form of CAR-T and placed it inside an established immunology business. The scientific question is whether ABBV-619 can turn temporary CAR expression into a durable immune reset.

Whether the acquisition was worth $2.1 billion will remain unanswered until longer-term patient data close that gap.

References

AbbVie. AbbVie to Acquire Capstan Therapeutics, Further Strengthening Commitment to Transforming Patient Care in Immunology. June 30, 2025. https://news.abbvie.com/2025-06-30-AbbVie-to-Acquire-Capstan-Therapeutics,-Further-Strengthening-Commitment-to-Transforming-Patient-Care-in-Immunology

2. AbbVie. AbbVie Completes Acquisition of Capstan Therapeutics. August 19, 2025. https://news.abbvie.com/2025-08-19-AbbVie-Completes-Acquisition-of-Capstan-Therapeutics

3. AbbVie Inc. Form 10-Q for the quarterly period ended September 30, 2025. Note 4, Capstan Therapeutics. https://www.sec.gov/Archives/edgar/data/1551152/000155115225000049/abbv-20250930.htm

4. Capstan Therapeutics. Capstan Therapeutics Announces Initiation of Phase 1 Trial of Lead In Vivo CAR-T Therapy, CPTX2309, for Treating Autoimmune Disease. June 11, 2025. https://www.biospace.com/press-releases/capstan-therapeutics-announces-initiation-of-phase-1-trial-of-lead-in-vivo-car-t-therapy-cptx2309-for-treating-autoimmune-disease

5. Are we there yet? The road to faster and more efficient CAR T cell manufacturing. Journal of Biological Engineering. 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC13126794/

6. AJMC. The Promise of In Vivo CAR T: Expanding Access Through Off-the-Shelf Innovation. 2026. Expert estimate. https://www.ajmc.com/view/the-promise-of-in-vivo-car-t-expanding-access-through-off-the-shelf-innovation

7. BioSpace. Capstan Secures $175M Oversubscribed Series B with Backing from J&J, Bayer and BMS. March 2024. https://www.biospace.com/capstan-secures-175m-oversubscribed-series-b-with-backing-from-j-and-j-bayer-and-bms

8. ACR Convergence 2024. Company-sponsored conference abstract. Profound B Cell Depletion and Repopulation with Predominantly Naïve B Cells in Non-Human Primates Achieved Through a Novel In Vivo CD8-Targeted Lipid Nanoparticle mRNA CAR. https://acrabstracts.org/abstract/profound-b-cell-depletion-and-repopulation-with-predominantly-naive-b-cells-in-non-human-primates-achieved-through-a-novel-in-vivo-cd8-targeted-lipid-nanoparticle-mrna-car/

9. Müller F, Taubmann J, Bucci L, et al. CD19 CAR T-Cell Therapy in Autoimmune Disease: A Case Series with Follow-up. New England Journal of Medicine. 2024;390:687 to 700. https://www.nejm.org/doi/full/10.1056/NEJMoa2308917

10. Wang Q, Xiao ZX, Zheng X, et al. In Vivo CD19 CAR T-Cell Therapy for Refractory Systemic Lupus Erythematosus. New England Journal of Medicine. 2025;393:1542 to 1544. Correspondence reporting five treated patients. https://pubmed.ncbi.nlm.nih.gov/40961420/

11. AbbVie Inc. Form 10-K for the year ended December 31, 2025. Item 1A, Risk Factors. Filed February 20, 2026. https://www.sec.gov/Archives/edgar/data/1551152/000155115226000008/abbv-20251231.htm

12. AstraZeneca. AstraZeneca to acquire EsoBiotec to advance cell therapy ambition. March 17, 2025. https://www.astrazeneca.com/media-centre/press-releases/2025/astrazeneca-to-acquire-esobiotec.html

13. Bristol Myers Squibb. Bristol Myers Squibb Strengthens and Diversifies Cell Therapy Portfolio with Acquisition of Orbital Therapeutics. October 10, 2025. https://news.bms.com/news/corporate-financial/2025/Bristol-Myers-Squibb-Strengthens-and-Diversifies-Cell-Therapy-Portfolio-with-Acquisition-of-Orbital-Therapeutics/default.aspx

14. Eli Lilly and Company. Lilly to acquire Orna Therapeutics to advance cell therapies. February 9, 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-acquire-orna-therapeutics-advance-cell-therapies

15. Eli Lilly and Company. Lilly to acquire Kelonia Therapeutics to advance in vivo CAR-T cell therapies. April 20, 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-acquire-kelonia-therapeutics-advance-vivo-car-t-cell

16. Johnson & Johnson. Johnson & Johnson Announces Collaboration with Sail Biomedicines to Advance In Vivo CAR-T Programs and Transform Autoimmune Disease Through Immune Reset. July 29, 2026. https://www.jnj.com/media-center/press-releases/johnson-johnson-announces-collaboration-with-sail-biomedicines-to-advance-in-vivo-car-t-programs-and-transform-autoimmune-disease-through-immune-reset