Here is the claim limitation that matters, and it is not the one most coverage names. Lilly's grant US12295987B2, "Method of using a GIP/GLP1 co-agonist for diabetes" (issued May 13, 2025), and its companion US12453758B2 (issued October 28, 2025) are method-of-use patents. They do not simply claim a chemical structure sitting in a vial; they claim administering a peptide that agonizes both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor to treat a metabolic condition. The dual-agonism recital is the spine of the claim.
Why does method-versus-composition scope decide so much? Because the two claim types fail and survive differently. A composition claim on a peptide sequence is narrow and crisp — change the sequence enough and you are outside it. A method-of-use claim reaches anyone practicing the claimed treatment with a qualifying molecule, which can be broader in effect but invites a different attack: that the method was obvious over prior single-receptor agonists. Reading these grants, the inventors (Alsina-Fernandez, Cabrera, Coskun) are claiming the therapeutic application of co-agonism, not merely a structure.
The genus-versus-species question lurks here. GLP-1 mono-agonism was well-trodden prior art; the inventive step Lilly is asserting is the combination of GIP plus GLP-1 activity in one agent for a defined indication. That narrows the genus to dual-receptor agonists and stakes the claim on the clinical consequence of adding the GIP arm. A challenger's natural move is to argue the GIP component was an obvious addition — which is exactly why the prosecution history and the specification's enablement of the dual mechanism carry the weight.
Note also the related landscape. US12215133B2, a 2025 grant to BrightGene Bio-Medical for a "GIP and GLP-1 dual receptor agonist, pharmaceutical composition, and use" (CPC C07K 14/605), shows that the dual-agonist concept is being claimed by more than one assignee and at the composition level as well as the method level. That coexistence is a signal: the white space is not in whether to co-agonize but in the specific sequences and the specific claimed uses.
Account for the term before anyone calls this a moat. A method-of-use grant is only as durable as its earliest priority date and any patent-term adjustment or extension stacked on top; the family's value depends on how long the claimed method stays protected against compounded and generic dual-agonists. The grant pages tell you what is claimed today. They do not, on their own, tell you the expiry math — and that math, not the claim language alone, is what an exclusivity analysis turns on.
The practitioner's takeaway: do not describe Lilly's tirzepatide IP as "a patent on tirzepatide." Describe it as a family of method-of-use claims built on a dual-receptor limitation, sitting alongside composition claims held by others. The independent claims recite a treatment, and the defensibility of the franchise lives or dies on how that recited method holds up against an obviousness challenge grounded in the long history of single-receptor GLP-1 agonism.