Patenting Stem Cell Therapies in the US: The Role and Risks of Product-by-Process Claims (Restem v Jadi Cell)

Key Takeaways

• Federal Circuit upheld product-by-process claim for MSC therapy
• Isolated cell interpreted as cell population, not single cell
• Prior art lacked same marker profile, so no anticipation
• Infringement requires practicing claimed process steps, not just product
• Decision shapes US stem‑cell patent drafting and enforcement

Summary

The U.S. Federal Circuit affirmed that product‑by‑process claims for stem‑cell therapies are novel when the underlying product itself is novel, rejecting Restem LLC’s challenge to US 9803176 covering an umbilical‑cord‑derived mesenchymal stem cell (MSC) product called JadiCell. The court interpreted the term “isolated cell” to refer to a population of cells, relying on prosecution history rather than the patent’s dictionary definition. It also held that prior‑art processes did not inherently produce the same surface‑marker profile, so the claim was not anticipated. While the ruling eases eligibility concerns, it underscores enforcement difficulties because infringement hinges on practicing the claimed steps.

Pulse Analysis

Product‑by‑process claims have become a tactical response to the post‑Myriad eligibility regime that bars patents on naturally occurring cells. By embedding limited process steps into the claim, applicants aim to demonstrate that the invention is more than a mere discovery, thereby sidestepping 35 U.S.C. § 101 objections. However, this strategy trades one hurdle for another: the claim’s enforceability now depends on proving that an alleged infringer performed the exact steps recited, not merely possessed a similar cell product.

In Restem v. Jadi Cell, the Federal Circuit dissected claim 1 of US 9803176, which described an "isolated cell" produced via a two‑step culture method and defined by a precise marker panel. The court rejected Restem’s argument that the term should be limited to a single cell, emphasizing that the prosecution history consistently treated the term as a cell population. Moreover, the court found that the cited prior‑art processes would have yielded different inter‑cellular interactions and marker expression, meaning the product was not inherently anticipated. This nuanced construction reinforces that product‑by‑process claims are judged on the product’s characteristics, not the mere existence of a similar manufacturing route.

For biotech companies, the ruling offers a double‑edged sword. On one hand, it validates the use of product‑by‑process language to navigate eligibility barriers, encouraging more robust US filings for MSC and other cell‑based therapies. On the other, it warns that enforcement will be more complex, requiring detailed process documentation and possibly limiting the claim’s breadth. Firms may now consider hybrid strategies—pairing product‑by‑process claims with direct product claims where feasible, or adding non‑natural features such as formulation excipients—to bolster both patentability and enforceability. The decision also highlights a divergence from European practice, where product‑per‑se claims are more readily granted, prompting US patentees to align global IP portfolios with jurisdiction‑specific nuances.