The US Court of Appeals for the Federal Circuit concluded that claims directed to “pharmaceutical batches” must be produced in accordance with a particular patent example, upholding a finding of non-infringement as to one patent and reversing a finding of infringement as to another. The Medicines Co. v. Mylan, Inc., Case Nos. 15-1113; -1151; -1181 (Fed. Cir., Apr. 6, 2017) (Dyk, J). 

Medicines has sold ANGIOMAX®, which is used to prevent blood clotting in patients undergoing cardiac catheterization, since 2001—“well before the critical date of the patents in suit.” The original manufacturing process for ANGIOMAX® resulted in “variable and sometimes high levels” of the impurity recited in the claims (Asp9), so Medicines developed an improved production process that employs an “efficient mixing” method to consistently produce batches with less than 0.6 percent Asp9. This improved process is the subject of the patents in suit.  

Medicines asserted that Mylan’s proposed generic would infringe two patents, each of which claimed “pharmaceutical batches” that contained less than 0.6 percent of a particular impurity. One of the asserted patents recited process steps, including “efficient mixing”; the other patent did not. The district court concluded that Mylan’s proposed generic would satisfy the purity limitation but found that the generic was not made using “efficient mixing” as claimed. Accordingly, the district court granted summary judgment of non-infringement as to the claims requiring “efficient mixing” but held that Mylan infringed the remaining claims. 

At the outset, the Federal Circuit explained that the claims could not be broadly construed to cover any pharmaceutical batches with less than 0.6 percent of the Asp9 impurity, because “[s]uch a construction would render the claims . . . invalid in light of Medicines’ numerous pre-critical-date sales of ANGIOMAX® batches having Asp9 levels below 0.6 percent.” Ultimately, the Federal Circuit concluded that the claimed pharmaceutical batches must be made using a particular process—specifically, the efficient mixing process described in Example 5 of the asserted patents. As the Court explained, the term “batches” requires “the use of a process that achieves batch consistency,” and efficient mixing was the only such process the patents disclosed. The Court then construed “efficient mixing” to require the conditions of Example 5, because as “the only embodiment of efficient mixing, Example 5 is ‘highly indicative of the scope of the claims.’” Accordingly, “one of ordinary skill in the art would rely on Example 5 to ascertain the metes and bounds of ‘efficiently mixing.’”

The Federal Circuit acknowledged that Example 5 was described as “non-limiting” in the specification, but explained that because “no other part of the patents’ written description sufficiently teaches the affirmative steps that constitute efficient mixing . . . we think it entirely appropriate to limit the term ‘efficient mixing’ to the sole portion of the specification that adequately discloses ‘efficient mixing’ to the public.” Thus, “incorporat[ing] the efficient mixing conditions of Example 5 is necessary to ‘tether the claims to what the specification[] indicate[s] the inventor actually invented.’”

Medicines argued that the claims did not require use of a specific process, and that, instead, the “batches” limitation was satisfied “whenever an accused infringer consistently produces batches having Asp9 levels below 0.6 percent.” The Federal Circuit characterized Medicines’ construction as “unworkable” because “proof of infringement would necessitate forward-looking assessments of whether an accused infringer’s production of future or ‘potential’ batches would be likely to generate Asp9 levels greater than ‘about 0.6%.’” The Court also rejected Medicines’ construction as impermissible because it “attempts to claim all solutions to the identified ‘impurities’ problem, without describing the entire range of solutions to that problem.” The Court emphasized that “efficient mixing must be defined in terms of the particular process or processes identified in the specification.” Because Mylan’s manufacturing process did not meet the “efficient mixing” requirement, the Court concluded that Mylan did not infringe any of the asserted claims. 

Practice Note: In cases where a known product is claimed based on an improved impurity profile, courts may construe the claims to require the process steps necessary to produce the impurity profile recited in the claims.