On June 16, 2026, the U.S. Patent and Trademark Office issued U.S. Patent No. 12,655,225, titled “Formulations of anti-CD38 antibodies for subcutaneous administration,” to Sanofi-Aventis U.S. LLC. CD38 is a glycoprotein heavily expressed on malignant plasma cells, which makes it one of the most commercially important targets in multiple myeloma. Sanofi’s anti-CD38 antibody isatuximab is named expressly in the patent’s specification as an embodiment of the claimed invention, anchoring this grant squarely to the company’s myeloma franchise rather than to an abstract chemistry exercise.
The important thing to understand at the outset is what kind of patent this is. It is not a composition-of-matter patent on a new antibody. The molecule — isatuximab — already exists and is already protected by earlier filings. This grant instead covers the formulation: the precise mixture of antibody plus excipients that lets a high-dose biologic be delivered as a small subcutaneous injection rather than a lengthy intravenous infusion. According to the abstract, the formulations combine a high concentration of antibody with a defined excipient set and hold the solution within tight physical-chemistry boundaries. The named inventors — Sylvain Huille, Thomas Ballet, Kiran Bangari, Ravi Chari, Bernardo Perez-Ramirez, and Filipe Vasco — are a formulation and process team, not a discovery team, which tells you exactly where the inventive contribution sits.
"The formulations include a high concentration of antibody, a viscosity lowering agent, a stabilizing agent, a buffering agent and a surfactant."— U.S. Patent No. 12,655,225, source
What the claims actually recite
The claim limitations that matter here are physical-chemistry boundaries, not sequence identities. The abstract sets two numerical guardrails: the viscosity of the solution is at most 25 mPa·s, and the pH of the solution is 5.9 to 7.0. Those numbers are the heart of the invention. Subcutaneous delivery of a monoclonal antibody is hard precisely because you must push a large protein dose into a small injection volume, and concentrated antibody solutions become viscous — viscous enough to be painful to inject and difficult to drive through a fine-gauge needle. A formulation that keeps a high-concentration anti-CD38 antibody below roughly 25 mPa·s while remaining stable is doing real work; that viscosity ceiling is the limitation a competitor would most need to design around. The excipient architecture is recited as a class-based set rather than a single named compound: a viscosity-lowering agent, a stabilizing agent, a buffering agent, and a surfactant. Drafting in functional classes broadens nominal scope, but it also invites the central question for any formulation patent — how much of that class space the specification actually enables and how the prosecution history narrowed it.
The classification confirms the read. The patent is assigned CPC symbols C07K 16/2896, C07K 2317/565, and C07K 2317/94 — the C07K neighborhood for immunoglobulins against specific targets, with the sub-symbols pointing at humanized constructs and stability characteristics. There is no C12N or A61K formulation-device symbol layered on top, which signals that the examiner treated this as an antibody-formulation case scoped by the protein and its solution properties rather than as a delivery-device or combination-therapy filing.
Why a formulation patent is a franchise tool
For an IP-literate reader, the strategic logic is familiar. A blockbuster biologic typically enters the market protected by a composition-of-matter patent on the antibody itself. As that primary patent ages, the originator builds a surrounding estate — formulation patents, method-of-treatment patents, dosing-regimen patents — each of which can carry its own term and each of which a biosimilar challenger must clear. A subcutaneous, low-viscosity formulation is one of the most valuable bricks in that wall, because it is not merely defensive: it changes the product. Shifting patients from an infusion chair to a self-administered or short in-office injection improves convenience, frees infusion capacity, and gives the originator a differentiated presentation that a future biosimilar of the intravenous product cannot automatically copy. The intended use is explicit — the formulations are described as finding use in treating CD38-positive hematological malignancies, including multiple myeloma, as well as autoimmune and inflammatory diseases.
That breadth of indication matters. By reciting CD38-positive malignancies broadly and naming multiple myeloma as the lead use — while also reaching toward autoimmune and inflammatory disease — the patent positions the formulation to follow the antibody wherever Sanofi takes it clinically. If isatuximab expands beyond its current oncology footprint, the subcutaneous formulation estate travels with it.
What to watch on scope and term
A formulation patent’s value lives almost entirely in its claim breadth and its expiry math, and three caveats apply. First, the abstract states embodiments — “in certain embodiments” the viscosity is at most 25 mPa·s and the pH is 5.9 to 7.0, and “in certain embodiments” the antibody is isatuximab. Embodiment language in an abstract is a guide to the disclosure, not a substitute for the issued independent claims; the enforceable scope is whatever those claims recite after prosecution. Second, functional excipient classes are only as strong as the specification’s enablement and the prior art — viscosity-lowering agents and standard antibody-stabilizing buffers are a crowded field, and a determined challenger would mine that art and the file history for narrowing arguments. Third, on timing: as a 2026-issued patent in a B2 grant, its term runs from the earliest non-provisional priority date in its chain, so the operative exclusivity window depends on how far back that priority reaches — a calculation that should account for any patent-term adjustment but that this grant document alone does not resolve.
The bottom line for the IP desk: this is a textbook lifecycle-management formulation grant. It does not re-monopolize the isatuximab molecule, but it does hand Sanofi a fresh, separately enforceable claim set over the high-concentration, low-viscosity subcutaneous presentation that biosimilar entrants would most want to replicate — and it does so with the convenience-and-differentiation upside that makes formulation IP worth far more than its modest technical footprint suggests. The claim limitations to watch are the viscosity ceiling and the pH window; the rest of the fight will be about how much of the excipient-class space the specification truly enabled.