Lutathera® (lutetium Lu 177 dotatate)
Case Name: Advanced Accelerator Applications, USA, Inc. v. Lantheus Medical Imaging, Inc., C.A. No. 24-95 (MN), C.A. No. 24-1161 (MN), 2026 WL 1747047 (D. Del. June 17, 2026) (Noreika, J.)
Drug Product and Patent(s)-in-Suit: Lutathera® (lutetium Lu 177 dotatate); U.S. Patent Nos. 10,596,276 (“the ’276 patent”), 12,151,003 (“the ’003 patent”), 12,161,732 (“the ’732 patent”), and 12,168,063 (“the ’063 patent”)
Nature of the Case and Issue(s) Presented: Lutathera is indicated for the treatment of somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (“GEP-NETs”). The asserted patents claim manufacturing processes and pharmaceutical compositions designed to stabilize Lutetium Lu 177 dotatate against radiolytic degradation, thereby extending shelf life and enabling centralized commercial manufacture and distribution.
Advanced Accelerator Applications (“ADACAP”) sued Lantheus under the Hatch-Waxman Act based on Lantheus’s ANDA seeking approval to market a generic version of Lutathera and separately sued Curium based on its § 505(b)(2) NDA for a competing Lutetium Lu 177 dotatate product. ADACAP asserted multiple claims across four patents directed to manufacturing processes and stabilized pharmaceutical formulations. Lantheus disputed infringement of one asserted process claim but stipulated that its product met the limitations of two asserted composition claims. Curium disputed infringement entirely. Both defendants asserted multiple invalidity defenses, including that all asserted claims were barred under the pre-AIA on-sale bar because ADACAP had commercially sold the claimed invention in Europe more than one year before the priority date. Following a five-day bench trial, the court held that although Lantheus infringed two composition claims, and that all asserted claims were invalid under the on-sale bar.
Why Defendants Prevailed: The court first addressed infringement issues before turning to validity. ADACAP argued that both defendants’ products satisfied the ’276 patent limitation requiring “at least one stabilizer against radiolytic degradation that is different from the first stabilizer” because DTPA functioned as a second stabilizer. The court rejected that argument. Although ADACAP’s experts testified that DTPA could theoretically scavenge free radicals, they performed no testing demonstrating that DTPA actually functioned as a stabilizer in either accused formulation. Instead, the intrinsic evidence consistently characterized DTPA as a chelating or sequestering agent rather than a radiolytic stabilizer, including the patents themselves, ADACAP’s own FDA submissions, and defendants’ regulatory filings. Thus, ADACAP failed to prove infringement of the asserted ’276 patent claims.
The court also held that prosecution history estoppel barred ADACAP from relying on the doctrine of equivalents to satisfy the patents’ stabilizer concentration limitations. During prosecution, ADACAP narrowed the claimed stabilizer concentration ranges to overcome prior art references teaching higher stabilizer concentrations. Because Curium’s product fell within the territory surrendered during prosecution, ADACAP could not recapture that subject matter through the doctrine of equivalents.
The court ultimately resolved the case on invalidity grounds based on the on-sale bar. Applying the Supreme Court’s two-part test from Pfaff, the court concluded that ADACAP commercially sold the claimed invention before the critical date and that the invention was ready for patenting at the time of those sales. Beginning years before the priority date, ADACAP sold thousands of Lutathera doses throughout Europe under compassionate use and named-patient programs, generating millions of dollars in revenue. The court rejected ADACAP’s argument that these programs were primarily experimental, finding that the company lacked evidence of structured experimentation, continued collecting the same manufacturing data after regulatory approval, and derived substantial commercial benefits from the sales, including significant profit margins, physician familiarity, and expanded market presence.
The court further found that the invention was ready for patenting well before the critical date. ADACAP’s NDA, filed more than one year before the critical date, provided a complete enabling disclosure of the claimed manufacturing processes and formulations. In addition, the court concluded that the invention had been reduced to practice no later than completion of the NETTER-1 Phase III clinical trial, which established that Lutathera successfully achieved its intended purpose. Because ADACAP commercially exploited the patented invention before filing its patent applications, the court held that every asserted claim was invalid under § 102(a).
