Actelion Pharmaceuticals Ltd v. Mylan Pharmaceuticals Inc.

United States Court of Appeals
for the Federal Circuit
______________________
ACTELION PHARMACEUTICALS LTD,
Plaintiff-Appellee
v.
MYLAN PHARMACEUTICALS INC.,
Defendant-Appellant
______________________
2022-1889
______________________
Appeal from the United States District Court for the
Northern District of West Virginia in No. 1:20-cv-00110-
JPB, Judge John Preston Bailey.
______________________
Decided: November 6, 2023
______________________
STEPHEN BLAKE K INNAIRD, Paul Hastings LLP, Wash-
ington, DC, argued for plaintiff-appellee. Also represented
by I GOR VICTOR T IMOFEYEV; CHRISTOPHER P. HILL , AARON
SELIKSON, SARAH SPENCER , MARK RUSSELL SPERLING,
BRUCE M. WEXLER , New York, NY.
ERIC T HOMAS WERLINGER , Katten Muchin Rosenman
LLP, Washington, DC, argued for defendant-appellant.
Also represented by T IMOTHY H. G RAY ; J ITENDRA MALIK,
Charlotte, NC; D EEPRO MUKERJEE , L ANCE SODERSTROM ,
New York, NY; J ILLIAN SCHURR, Chicago, IL.
______________________
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Before REYNA, STOLL , and STARK, Circuit Judges.
STOLL , Circuit Judge.
The issue on appeal in this patent case is the meaning
of “a pH of 13 or higher.” More specifically, the issue in-
volves understanding what the significant digits are for “a
pH of 13.” The district court did not address extrinsic evi-
dence, including textbooks, explaining how a person of or-
dinary skill in the art would view the significant digits for
a pH value. Because this is a case where the district court
must address the extrinsic evidence to understand how a
person of ordinary skill in the art would understand the
claim language, we vacate the district court’s claim con-
struction order with respect to the term “a pH of 13 or
higher” and the judgment of infringement, and remand for
the district court to consider the extrinsic evidence and its
impact on claim construction.
BACKGROUND
The drug at issue in this Abbreviated New Drug Appli-
cation (ANDA) litigation is epoprostenol, a naturally occur-
ring substance that is useful for treating cardiovascular
diseases. Epoprostenol was discovered in the early 1980s
and was first brought to market under the brand name Flo-
lan® in 1995. epoprostenol is unstable in water, it was pre-
pared as a freeze-dried, or lyophilized, powder for use in
the Flolan composition.
Actelion Pharmaceuticals LTD owns two patents—
U.S. Patent Nos. 8,318,802 and 8,598,227—both directed
to improved epoprostenol formulations.1 According to the
patent specification, there was a “need for epoprostenol
1 The patents are from the same family and have ma-
terially similar specifications. For ease, and consistent
with the parties’ briefing on appeal, we primarily cite the
’802 patent.
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formulations that can be reconstituted with commercially
available IV fluids and do not require refrigeration after
reconstitution until use.” ’802 patent col. 4 ll. 1–4. The in-
ventor “unexpectedly found that epoprostenol solution in
the presence of an alkalinizing agent, and high pH (>11) is
very stable compared to Flolan.” Id. at col. 4 ll. 8–10.
Claim 11 of the ’802 patent is representative of the as-
serted claims:
11. A lyophilisate formed from a bulk solution com-
prising:
(a) epoprostenol or a salt thereof;
(b) arginine;
(c) sodium hydroxide; and
(d) water,
wherein the bulk solution has a pH of 13 or higher,
and wherein said lyophilisate is capable of being
reconstituted for intravenous administration with
an intravenous fluid.
Id. at col. 19 ll. 13–20 (emphasis on disputed term). The
term “a pH of 13 or higher” appears in independent claims
1 and 11 of the ’802 patent, and independent claims 16, 22,
32, and 40 of the ’227 patent.
Actelion sells its epoprostenol product, an epoprostenol
sodium for injection, under the brand name Veletri ®. The
’802 and ’227 patents are listed in the FDA’s publication
“Approved Drug Products with Therapeutic Equivalence
Evaluations,” commonly known as the Orange Book, as
covering Veletri.
Mylan Pharmaceuticals Inc. sought approval to manu-
facture and sell a generic epoprostenol sodium for injection
by filing an ANDA with the FDA. Its ANDA contained a
certification that the ’802 and ’227 patents’ claims were in-
valid or would not be infringed by the ANDA product. See
21 U.S.C. § 355(j)(2)(A)(vii)(IV). After receiving notice of
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that certification, Actelion sued Mylan for infringement of
claims 1, 6, 8, 10, 11, 16, 18, 20, and 22 of the ’802 patent
and claims 1–3, 8, 10, 12, 14, 16, 18–22, and 24–42 of the
’227 patent. See 35 U.S.C. § 271(e)(2).
Relevant here, the parties dispute the meaning of the
claim term “a pH of 13 or higher.” Both parties proposed
the plain and ordinary meaning of the term but disagreed
on what that means. J.A. 85.
Actelion argued that “a pH of 13” in the context of the
asserted claims is “a value of acidity that is given as an
order of magnitude that is subject to rounding.” Actelion
Pharms. LTD v. Mylan Pharms. Inc., No. 1:20-CV-110,
Actelion’s Redacted Opening Claim Constr. Br. 15–16, ECF
No. 76 (Opening Claim Constr. Br.). More specifically,
Actelion’s proposal would allow a pH of 12.5, which rounds
to 13, to read on the claim limitation of “a pH of 13 or
higher.” By contrast, Mylan argued that the proper con-
struction cannot cover any pH values less than 13. Actelion
Pharms. LTD v. Mylan Pharms. Inc., No. 1:20-CV-110,
Mylan Pharm. Inc.’s Responsive Claim Constr. Br. 1, ECF
No. 75 (Responsive Claim Constr. Br.).
Actelion attacked Mylan’s construction as, among
other things, “chang[ing] the number of significant digits”
and conflicting with the plain language of the claim. Open-
ing Claim Constr. Br. 15. It explained that “[t]o describe a
specific pH value, and not an order of magnitude, there
would need to be a significant figure to the right of the dec-
imal point or clear context to the contrary.” Id. at 11. For
support, Actelion cited three textbooks: Hans van Kessel
et al., CHEMISTRY 12, Chapter 8.1 (2003) (“Kessel”), Frank
Mustoe et al., CHEMISTRY 11, Chapter 10 (2001) (“Mustoe”),
and Martin S. Silberberg, CHEMISTRY : THE MOLECULAR
N ATURE OF MATTER AND CHANGE, Chapter 18 (4th ed. 2006)
(“Silberberg”). Id. at 11–12.
Mylan disagreed with Actelion’s “ordinary rounding
rules” and account of “significant figures.” Responsive
Claim Constr. Br. 1. But it explained that if the district
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court were inclined to include measurement errors for a pH
of 13, Actelion’s three chemical textbooks support a nar-
rower range of 12.995–13.004. Id. at 18–22 (citing J.A. 308
(Kessel); J.A. 343 (Mustoe); J.A. 402 (Silberberg)).
The textbooks explain how to calculate pH and identify
significant figures for pH values. Silberberg explains that:
As with any measurement, the number of signifi-
cant figures in a pH value reflects the precision
with which the concentration is known. However,
it is a logarithm, so the number of significant fig-
ures in the concentration equals the number of dig-
its to the right of the decimal point in the
logarithm[.]
J.A. 400 (emphasis in original). Mustoe states: “How do
you determine the number of significant digits in a pH?
You count only the digits to the right of the decimal point.”
J.A. 339. Kessel echoes the same concept. See J.A. 304–05
(describing the formula for calculating pH, pH = –
log ([H+(aq)]), and explaining that “the number of digits fol-
lowing the decimal point in the pH value is equal to the
number of significant digits in the hydrogen ion concentra-
tion,” the hydrogen ion concentration being [H+(aq)]).
The district court did not address this extrinsic evi-
dence. Instead, it adopted Actelion’s proposed construction
based on the intrinsic record alone. See Actelion Pharms.
Ltd. v. Mylan Pharms. Inc., No. 1:20-CV-110, 2022 WL
446788, at *9 (N.D.W. Va. Feb. 14, 2022) (Decision). The
court explained that the claims “consistently expressed ‘a
pH of 13’ with two significant figures” and that the “claim
language provides no basis for inferring any higher level of
precision.” Id. at *5. It reasoned that, “under its conven-
tional significant figure meaning, the term a ‘pH of 13’
would ordinarily encompass those values that round up or
down to 13, 12.5 to 13.4.” Id. (citing Viskase Corp. v. Am.
Nat’l Can Co., 261 F.3d 1316, 1320 (Fed. Cir. 2007)).
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Turning to the specification, the court concluded that
“there is nothing to indicate that Actelion intended to im-
port any higher degree of precision to ‘a pH of 13’ as it is
articulated in the claims at issue.” Id. at *7. Similarly, the
court was “unpersuaded that the prosecution history re-
quires it to read an increased degree of precision into the
claim language.” Id.
Lastly, the court engaged with AstraZeneca AB
v. Mylan Pharmaceuticals Inc., 19 F.4th 1325 (Fed. Cir.
2021). Decision, 2022 WL 446788, at *8–9. The district
court distinguished AstraZeneca, reasoning that in this
case, unlike AstraZeneca, “neither the specification nor
prosecution history demonstrates that the inventor in-
tended to employ a more precise level of exactness” for the
claimed term. Id. at *8.
Following claim construction, the parties stipulated to
final judgment of infringement in favor of Actelion. The
district court entered the judgment on June 6, 2022.
Mylan appeals. We have jurisdiction under 28 U.S.C.
§ 1295(a)(1).
D ISCUSSION
When a district court reviews only intrinsic evidence
(i.e., the patent claims, specification, and prosecution his-
tory), its claim construction will amount solely to a ruling
of law and will therefore be subject to de novo review. See
MasterMine Software, Inc. v. Microsoft Corp., 874 F.3d
1307, 1310 (Fed. Cir. 2017). In cases where the district
court reviews extrinsic evidence to resolve factual disputes,
such as the background science or the meaning of a term to
a skilled artisan, however, those determinations must be
reviewed under the clear error standard. Id. But the
court’s ultimate interpretation of the claim in light of the
facts as found remains a conclusion of law subject to de
novo review on appeal. Id.
The sole and narrow question before us involves the
meaning of “a pH of 13 or higher,” in the context of the ’802
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and ’227 patents. Mylan argues that the claim term cre-
ates a floor at 13, beneath which the pH cannot fall. Ap-
pellant’s Br. 3. In the alternative, Mylan argues that if a
margin of error for a pH of 13 is needed, a pH of 13 would
involve rounding to the hundredths place, encompassing
12.995–13.004. Reply Br. 12. In contrast, Actelion argues
that the district court correctly construed the claim term
as including rounding to the ones place, noting that “a nu-
merical value includes rounding based on the inventor’s se-
lection of significant figures in the claims where the
intrinsic record does not indicate otherwise.” Appellee’s
Br. 26. As previewed, the intrinsic evidence is rather
equivocal. At the same time, the extrinsic evidence relied
on by the parties—but unconsidered by the district court—
appears highly relevant to how a person of ordinary skill
would understand the language “a pH of 13.”
We start with the claim language. See Sunovion
Pharms., Inc. v. Teva Pharms. USA, Inc., 731 F.3d 1271,
1276 (Fed. Cir. 2013) (explaining that we first, and primar-
ily, rely on intrinsic evidence like the claims themselves
when construing claim terms). The claim language, “a pH
of 13 or higher,” is a range with a specified lower limit.
Based on this, Mylan argues that the lower end of the
claimed range is not subject to the rules of rounding and
that this court “has held that there is no need to ‘read in an
implicit range’ because an ‘open-ended range’ like ‘X and
up’ already expressly represents uncertainty at the top
end.” Reply Br. 10–11 (first citing Quantum Corp.
v. Rodime, PLC, 65 F.3d 1577, 1581 (Fed. Cir. 1995); and
then Adams Respiratory Therapeutics, Inc. v. Perrigo Co.,
616 F.3d 1283, 1292 (Fed. Cir. 2010)). We disagree with
Mylan. That other cases have found precision in ranges
specific to the claims at issue there, is not of great signifi-
cance to our analysis here. In other words, there is no blan-
ket rule that ranges, or specifically open-ended ranges,
must foreclose rounding. This is especially true in this case
where, though not expressly specified, there is in fact an
upper limit in the claim because, as a matter of science, pH
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values are often said to range from 0 to 14. See, e.g.,
J.A. 340, 400.
Unlike other claim terms, the disputed claim term
lacks approximation language like “about.” See, e.g.,
’802 patent col. 18 ll. 66–67 (“the bulking agent is present
at about 1-10%” (emphasis added)); ’227 patent col. 18
ll. 44–45 (“about –30 degrees C. at the rate of approxi-
mately 0.5 to 0.7 C./min.” (emphases added)).
Based on this, Mylan argues that the absence of ap-
proximation language must mean that “a pH of 13” is ex-
actly 13. Appellant’s Br. 36–38. Otherwise, Mylan argues,
“13” and “about 13” would both imply rounding, making the
approximation language superfluous. Appellant’s Br. 38
(citing PPC Broadband, Inc. v. Corning Optical Commc’ns
RF, LLC, 815 F.3d 747, 752–53 (Fed. Cir. 2016) (applying
the canon of construction that different terms have differ-
ent meanings)). Indeed, we have held that a claim con-
struction giving meaning to all terms in a claim is
preferrable over one that does not. See, e.g., Merck & Co.
v. Teva Pharms. USA, Inc., 395 F.3d 1364, 1371–72
(Fed. Cir. 2005).
On the other hand, Actelion argues that rounding is re-
quired because approximation language like “about” sig-
nals different variations than those of rounding. See
Appellee’s Br. 34–35. Actelion also argues that “it is not
practically possible to measure exact pH values” because to
get an “exact” measurement “one would have to count every
hydrogen ion in solution, which is not scientifically possi-
ble.” Appellee’s Br. 30 & n.8.
Ultimately, we do not find the absence of approxima-
tion language dispositive here. We reject any invitation to
create a bright-line rule—either that language like “pre-
cisely” or “exactly” is always needed to avoid rounding or
that the lack of approximation language, even when it may
be found elsewhere in the claims, dictates a precise value.
In other words, we find both views equally plausible here;
that the absence of approximation language might suggest
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no approximation, but that the nature of measuring a pH
value might nonetheless reasonably require a margin of er-
ror.2
Finally, the claims do not recite just any measurement
of 13 or higher; rather they are directed to a pH of 13 or
higher. Thus, the district court should consider whether a
pH of 13 carries any meaning to a person of ordinary skill
in the art as regards precision of measurement, significant
digits, or rounding. The parties submitted extrinsic evi-
dence appearing to address this issue, but the district court
did not discuss it.
We thus turn to the specification, which is “always
highly relevant to the claim construction analysis,” and
“the single best guide to the meaning of a disputed term.”
Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir.
2005) (quoting Vitronics Corp. v. Conceptronic, Inc.,
90 F.3d 1576, 1582 (Fed. Cir. 1996)). Here, the specifica-
tion reveals that the inventor inconsistently described the
level of specificity for a pH of 13.
The specification explains that “[t]he pH of the bulk so-
lution is preferably adjusted to about 12.5-13.5, most pref-
erably 13.” ’802 patent col. 5 ll. 41–43. Mylan argues that
this shows that the inventor (1) knew how to use approxi-
mation language when it wanted (“about 12.5-13.5”) and
chose not to for a pH of 13; (2) distinguished a pH value of
“12.5” from that of “13”; and (3) distinguished a range
(“12.5-13.5”) from a definite value (“13”). Appellant’s
Br. 43–44. In other words, Mylan argues that “13” in “a pH
of 13 or higher” cannot be an approximation or range of
values, especially a range that encompasses 12.5. Id.
Actelion counters, among other things, that “13” should al-
low rounding or else a preferred embodiment of the
2 Whether a pH value can be measured precisely—
and to what degree—is a question of fact which we leave
for the district court to determine in the first instance.
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invention, meaning a pH of about 12.5 to 13.5, would be
excluded from the claim scope. Appellee’s Br. 42–43.
There is more. The specification seems to equate a pH
of “13.0” to that of “13.” Example 4 describes screening sev-
eral “formulations with the pH of bulk solution . . . adjusted
between 10.5 and 13.0.” ’802 patent col. 10 ll. 63–64. Ta-
bles 8 and 9 show the resulting stability data and display
a bulk solution pH as “13” with no decimal point. Mylan
argues that this shows that the inventor equated a pH of
“13” with “13.0.” Appellant’s Br. 44–45. This may be so.
But the specification uses both “13” and “13.0”—and vari-
ous degrees of precision for pH values generally—through-
out. See, e.g., ’802 patent col. 7 ll. 16–17 (“The pH of the
bulk solution is adjusted to 13.0 with the base.”), col. 11
l. 59 (“the pH of bulk solution adjusted to 13”), Tbl. 19 (“pH
11.58”). Said otherwise, the specification supplies the
same clarity as to the desired level of precision as muddied
water.
This specification stands in sharp contrast to that in
AstraZeneca, which helped guide the claim construction at
issue there. The issue in AstraZeneca was whether the con-
centration of PVP as “0.001%” meant 0.001% within one
significant figure—encompassing a concentration of
0.0005% to 0.0014%—or a narrower meaning of precisely
0.001% with even more minor variations. 19 F.4th at 1329.
The specification explained that stability was one of the
most important factors when determining whether a com-
pound could develop into a therapeutically useful pharma-
ceutical product. Id. at 1330. It made clear that a
formulation comprising 0.001% w/w PVP is more stable
than, and different from, a formulation with 0.0005% w/w
PVP. Id. at 1332. Indeed, Figure 5 of the patent-at-issue
showed that 0.0005% w/w PVP was one of the least stable
formulations tested. Id. at 1331–32. Thus, the specifica-
tion supported a claim construction that would exclude
0.0005% and focus on smaller variations. The data in the
specification showed how slight differences in the
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concentration of PVP, down to four decimal places, mat-
tered for stability in the context of that invention. Id.
at 1332.
To be sure, the issue here is also stability. But while
the specification may state that “the stability of epo-
prostenol is better at pH 13 compared to lower pH sam-
ples,” the specification does not evaluate the stability of
epoprostenol at pH values between 12 and 13. ’802 patent
col. 11 ll. 54–56, Tbl. 8. So the specification does not show
whether slight differences in the pH, at least between a pH
of 12 and 13, matter for stability in the context of this in-
vention. In sum, the scope of the claim term remains un-
clear even after consulting the specification.
We next turn to the prosecution history for guidance.
The prosecution history “can often inform the meaning of
the claim language by demonstrating how the inventor un-
derstood the invention and whether the inventor limited
the invention in the course of prosecution, making the
claim scope narrower than it would otherwise be.” Phillips,
415 F.3d at 1317 (citing Vitronics, 90 F.3d at 1582–83).
Here, the prosecution history does not provide clarity.
The inventor amended the claim language at issue sev-
eral times, including: “a pH of greater than 11,” J.A. 116;
“a pH of greater than 12,” J.A. 126; and “a pH of at least
12,” J.A. 144. The Examiner rejected the earlier claim lan-
guage because they found that the prior art “teaches that
their composition has a pH of at least 9 and the solutions
are capable of being reconstituted to a pH of greater than
12, which encompasses pH of 13 and 14.” J.A. 152. In the
final rejection, the Examiner explained that the inventor
had “not demonstrated that compositions with a pH of
greater than 12 are superior to those of [a sample with a
pH of 10.5], [but] they have demonstrated that for a pH of
13 there is a significant difference.” J.A. 661. The inventor
thereafter amended its claim from “a pH of greater than
12” to “a pH of 13 or higher.” J.A. 177. The Examiner’s
reasons for allowance explained that the inventor “has
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demonstrated unexpected results with respect to composi-
tions made with solutions of pH 13 or higher as shown in
tables 8 and 9 of the specification.” J.A. 108. Specifically,
“stability of the composition is greatly increased when re-
constituted versus compositions with a pH of 12 or lower.”
Id. And that this “is an unexpected result as the prior art
does not teach pH of 13 as having advantages over pH 11
or 12.” Id.
In short, the prosecution history shows that the Exam-
iner drew a distinction between the stability of a composi-
tion with a pH of 13 and that of 12. Such distinction,
however, does not illuminate the narrower issue of whether
a pH of 13 could encompass values that round to 13, in par-
ticular 12.5. Tables 8 and 9 simply do not compare compo-
sitions with pH values of 13 to those with a pH between 12
and 13.3
We find that this case is one where the proper claim
construction cannot be reached without the aid of extrinsic
evidence, and that the district court should have consid-
ered, at minimum, the textbook excerpts offered and ad-
dressed by the parties. The Supreme Court has made clear
that there are cases where the district court must “look be-
yond the patent’s intrinsic evidence and . . . consult extrin-
sic evidence in order to understand, for example, the
background science or the meaning of a term in the
3 Mylan also flags that the inventor conceded that
the term “a pH of 13 or higher” was “duplicative” of “a pH
of at least 13 or higher.” Appellant’s Br. 51; Reply Br. 10
(citing J.A. 97, 181). It argues that if the district court is
correct that the phrase “greater than 13” draws a line for-
feiting values below 13, then so too must the phrase “at
least 13” and, thus, the inventor knew it claimed a floor of
13. Appellant’s Br. 66 (citing Decision, 2022 WL 446788,
at *7). We disagree. The term “greater than X” does not
encompass “at least X.” At minimum, the former excludes
the value X while the latter includes it.
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relevant art during the relevant time period.” Teva
Pharms. USA, Inc. v. Sandoz, Inc., 574 U.S. 318, 331
(2015). And we have previously stated that “[o]nly if a dis-
puted claim term remains ambiguous after analysis of the
intrinsic evidence should the court rely on extrinsic evi-
dence.” Pickholtz v. Rainbow Techs., Inc., 284 F.3d 1365,
1372–73 (Fed. Cir. 2002) (citing Vitronics, 90 F.3d at 1583).
In such cases, the district court must “make subsidiary fac-
tual findings about that extrinsic evidence,” and such find-
ings are the evidentiary underpinnings of claim
construction. Teva, 574 U.S. at 332. It is not for this court
to make those findings in the first instance. We decline to
decide, for example, how many significant figures “a pH of
13” has or what it would mean for a number—either for a
pH value or for the concentration of hydrogen ions—to have
zero significant figures. Instead, we leave those and other
relevant factual questions that might arise based on the
extrinsic evidence, including the three textbooks, for the
district court to address in the first instance.
We have considered the parties’ remaining arguments
on appeal and find them unpersuasive.
CONCLUSION
For the reasons above, we vacate the district court’s
judgment of infringement, and remand for the district
court to consider the extrinsic evidence and its impact on
claim construction.
VACATED AND REMANDED
COSTS
No costs.
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