Ardelyx, Inc., Et Al . v. Robert F. Kennedy , J R., Secretary of Health and Human Services

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued September 25, 2025 Decided June 26, 2026
No. 24-5290
ARDELYX, I NC., ET AL .,
APPELLANTS
v.
ROBERT F. KENNEDY , J R., SECRETARY OF HEALTH AND
HUMAN SERVICES , ET AL.,
APPELLEES
Appeal from the United States District Court
for the District of Columbia
(No. 1:24-cv-02095)
Michael E. Bern argued the cause for appellants. With him
on the briefs were James E. McCollum, Jr., Amit K. Sharma,
Christine C. Smith, Alexander G. Siemers, Delia Tasky, and
Nicholas L. Schlossman.
Caroline D. Lopez, Attorney, U.S. Department of Justice,
argued the cause for appellees. With her on the brief were
Yaakov M. Roth, Acting Assistant Attorney General, Michael
S. Raab, Attorney, and David L. Hoskins, Deputy Associate
General Counsel for Litigation, U.S. Department of Health and
Human Services. Anna O. Mohan, Attorney, U.S. Department
of Justice, entered an appearance.

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Before: CHILDS and PAN , Circuit Judges, and GINSBURG ,
Senior Circuit Judge.
Opinion for the Court filed by Senior Circuit Judge
GINSBURG.
GINSBURG, Senior Circuit Judge: In 2008 the Congress
directed the Secretary of Health and Human Services to
“implement a payment system” that would provide a “single
payment” for the reimbursement of “renal dialysis services”
under Medicare, a federal health insurance program. See
42 U.S.C. § 1395rr(b)(14)(A)(i). In 2010 the Secretary, acting
through the Centers for Medicare & Medicaid Services,
defined “renal dialysis services” to include drugs with “only an
oral form” — i.e., oral-only drugs — furnished for the treat-
ment of end-stage renal disease. 42 C.F.R. § 413.171(3)
(2011). In 2024 the CMS identified XPHOZAH, an oral-only
drug manufactured by Ardelyx, Inc., as a renal dialysis service
covered by the new payment system starting on January 1,
2025. Before then, XPHOZAH, along with other orally admin-
istered drugs, had been reimbursed separately from the bundled
payment under Medicare Part D.
Ardelyx, together with a healthcare research and advocacy
organization and an organization representing the interests of
kidney patients, challenged the CMS’s definition of “renal
dialysis services” as including oral-only drugs and the identifi-
cation of XPHOZAH as a renal dialysis service. * The district
court dismissed Ardelyx’s complaint for lack of jurisdiction on
the ground that the challenged actions were “identification[s]
of renal dialysis services” within the meaning of 42 U.S.C.
* The Department of Health and Human Services, the Secretary of
Health and Human Services, the CMS, and the Administrator of the
CMS are all defendants and appellees in this lawsuit. For simplicity
we refer to them collectively as the CMS.

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§ 1395rr(b)(14)(G), which bars judicial review of such actions
by the Secretary. Ardelyx, Inc. v. Becerra (Ardelyx I), 757 F.
Supp. 3d 37, 46-47 (D.D.C. 2024). We agree and affirm the
dismissal of Ardelyx’s complaint.
I. Background
End-stage renal disease (ESRD) is a form of chronic
kidney disease in which an individual’s kidneys can no longer
function on their own. Patients with ESRD who do not receive
a kidney transplant will die unless they receive dialysis treat-
ment several times per week. Medicare covers the cost of dial-
ysis for patients suffering from ESRD. See 42 U.S.C. §§ 426-
1, 1395rr(a).
A. Statutes and Regulations
In 1981 the Congress established a prospective payment
system for the reimbursement of renal dialysis services in order
to curb runaway costs. See Omnibus Budget Reconciliation Act
of 1981, Pub. L. No. 97-35, § 2145, 95 Stat. 357, 799-800.
Under this system, renal dialysis facilities and other providers
of renal dialysis services would receive a prospective payment
per treatment at a prescribed rate, regardless of their actual
costs. See 48 Fed. Reg. 21254, 21260/3 (1983). This payment
covered services including “routinely provided drugs, labora-
tory tests, and supplies.” 75 Fed. Reg. 49030, 49032/1 (2010).
A facility could retain any amount of the prospective payment
that exceeded its actual costs. 48 Fed. Reg. at 21261/1. Certain
items, such as erythropoiesis stimulating agents (ESAs), orally
administered drugs, and most injectable drugs were reimbursed
separately under Medicare Parts B or D.
The Congress believed this system would “encourage the
more efficient delivery of dialysis services.” 42 U.S.C.
§ 1395rr(b)(7). The system, however, also gave facilities an

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incentive to use the separately reimbursed items to treat ESRD
because doing so allowed them to increase their total reim-
bursement. By 2010 these separately reimbursed items
accounted for “40 percent of total spending for outpatient
maintenance dialysis.” 75 Fed. Reg. at 49032/2.
In order to bring that spending under control, the Congress
enacted the Medicare Improvements for Patients and Providers
Act of 2008, Pub. L. No. 110-275, § 153, 122 Stat. 2494, 2553.
The MIPPA instructed the Secretary to “implement a payment
system under which a single payment is made under this sub-
chapter to a provider of services or a renal dialysis facility for
renal dialysis services (as defined in subparagraph (B)) in lieu
of any other payment.” 42 U.S.C. § 1395rr(b)(14)(A)(i).
Subparagraph (B), § 1395rr(b)(14)(B), defines “renal dialysis
services” as follows:

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For purposes of this paragraph, the term “renal
dialysis services” includes--
(i) items and services included in the
composite rate for renal dialysis
services as of December 31, 2010;
(ii) erythropoiesis stimulating agents
and any oral form of such agents that
are furnished to individuals for the
treatment of end stage renal disease;
(iii) other drugs and biologicals that are
furnished to individuals for the
treatment of end stage renal disease
and for which payment was (before
the application of this paragraph)
made separately under this
subchapter, and any oral equivalent
form of such drug or biological; and
(iv) diagnostic laboratory tests and other
items and services not described in
clause (i) that are furnished to
individuals for the treatment of end
stage renal disease.†
Subparagraph (B) goes on to exclude vaccines from the defini-
tion of “renal dialysis services.”
The Congress also limited review of the Secretary’s
actions with respect to the services covered by the new pay-
ment system. As relevant here, the Congress provided that
† For consistency with the district court’s opinion, we refer to these
categories as “subparts” of subparagraph (B).

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“[t]here shall be no administrative or judicial review” of the
Secretary’s “identification of renal dialysis services included in
the bundled payment.” Subparagraph (G).
In 2009 the CMS published a notice of proposed rulemak-
ing to implement the new prospective payment system. See
74 Fed. Reg. 49922. The CMS explained that it believed sub-
part (B) (iii) required it to include in the bundled payment “all
drugs and biologicals formerly payable under either Medicare
Part B or Part D used to treat ESRD, regardless of the route of
administration,” one effect of which was to include oral-only
drugs. Id. at 49928/2-3. The CMS acknowledged that one could
read “any oral equivalent form of such drug or biological” at
the end of subpart (B)(iii) as “limit[ing] the scope of the drugs
and biologicals included in the bundle to only oral versions of
injectables (or other non-oral routes of administration).” Id. at
49928/3. Still, the CMS rejected that reading as “unduly
constrained” because it would undermine the Congress’s intent
to include “all renal dialysis services furnished to ESRD
patients in a comprehensive payment bundle.” Id. The CMS
alternatively invoked subpart (B)(iv), which covers “other
items and services not covered in [subpart (B)] (i),” to support
its inclusion of oral-only drugs in the bundled payment. Id.
In 2010 the CMS published the final rule implementing the
bundled payment system. 75 Fed. Reg. 49030. In response to
the “[m]any comments” it had received disagreeing with its
reading of “renal dialysis services” to include oral-only drugs,
see id. at 49038/2, the agency explained its view that the refer-
ence to oral equivalents in subpart (B)(iii) “pertains to the oral
versions of injectable drugs.” Id. at 49039/1. The CMS con-
strued the reference earlier in subpart (B)(iii) to “other drugs
[covered] under this [subchapter]” as including oral-only drugs
in the definition of “renal dialysis services.” Id. (cleaned up).
In case the agency was wrong about the scope of subpart

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(B)(iii), it again invoked subpart (B)(iv) in further support of
its decision, characterizing that subpart as a “residual or catch
all category for drugs which do not fall under the scope of those
specified renal dialysis services identified” in subparts (ii) and
(iii). Id. As a result, the final rule defines “renal dialysis
services” reimbursed under the bundled payment to include:
Other drugs and biologicals that are furnished to
individuals for the treatment of ESRD and for
which payment was (prior to January 1, 2011)
made separately under Title XVIII of the Act
(including drugs and biologicals with only an
oral form).
42 C.F.R. § 413.171(3).
The CMS set an effective date of January 1, 2014 for the
inclusion of oral-only drugs in the bundled payment to allow
facilities, providers, pharmacies, and Medicare Part D plans to
make necessary adjustments. 75 Fed. Reg. at 49044/1. Before
the regulation went into effect, the Congress thrice delayed
implementation of the bundled payment with respect to oral-
only drugs, making the effective date January 1, 2025. See
American Taxpayer Relief Act of 2012, Pub. L. No. 112-240,
§ 632(b), 126 Stat. 2313, 2354 (2013) (delaying implementa-
tion until January 1, 2016); Protecting Access to Medicare Act
of 2014, Pub. L. No. 113-93, § 217(a), 128 Stat. 1040, 1061
(extending the delay until January 1, 2024); Achieving a Better
Life Experience Act of 2014, Pub. L. No. 113-295, § 204, 128
Stat. 4010, 4065 (extending the delay until January 1, 2025).
Along the way, the Congress also imposed other requirements
related to the inclusion of oral-only drugs in the bundled pay-
ment. See § 632(b), 126 Stat. at 2354 (ordering the CMS to
monitor the bone and mineral metabolism in ESRD patients
“[w]ith respect to the implementation of oral-only ESRD-

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related drugs in the ESRD prospective payment system”);
§ 632(d), 126 Stat. at 2354-55 (directing the Government
Accountability Office to report on “the Secretary’s
preparations to implement payment for oral-only ESRD-
related drugs in the bundled prospective payment system”);
§ 217(d)(3), 128 Stat. at 1062-63 (requiring the CMS to
establish performance measures for facilities regarding the
quality of patient care “that are specific to the conditions
treated with oral-only drugs”).
B. The Identification of XPHOZAH
XPHOZAH is an oral-only drug manufactured by Ardelyx
to treat hyperphosphatemia, a condition characterized by an
abnormally high level of phosphate in the blood. Advanced
kidney failure is the leading cause of hyperphosphatemia,
which occurs in 80% of ESRD patients on maintenance dialy-
sis. Patients with ESRD may begin treating hyperphosphatemia
with phosphate binders, which prevent phosphate from enter-
ing the bloodstream by attaching to phosphate in the
gastrointestinal tract. Of those patients with ESRD on mainte-
nance dialysis who have hyperphosphatemia, however, 70%
experience an inadequate response to phosphate binders and
cannot maintain their target phosphate level.
In a declaration filed in support of its motion for a prelim-
inary injunction, Ardelyx describes XPHOZAH as a “novel
treatment option” for those patients. XPHOZAH blocks phos-
phate from entering the bloodstream through a different
mechanism of action than phosphate binders. According to its
FDA-approved label, XPHOZAH is indicated for use only by
“adults with chronic kidney disease . . . on dialysis as add-on
therapy in patients who have an inadequate response to phos-
phate binders or who are intolerant of any dose of phosphate
binder therapy.” The label also tells prescribers to “[i]nstruct

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patients not to take XPHOZAH right before a hemodialysis
session.”
In August 2023 — with the inclusion of oral-only drugs in
the bundle still more than a year away — Ardelyx submitted a
letter to the CMS asking it to continue excluding oral-only
drugs such as XPHOZAH from the definition of “renal dialysis
services” beyond January 1, 2025. Two months later,
XPHOZAH received FDA approval and first became available
to patients. XPHOZAH was initially covered under Medicare
Part D and reimbursed separately from the bundled payment.
On May 13, 2024 the CMS notified Ardelyx that it had
“identified XPHOZAH™ [as] a renal dialysis service under
42 C.F.R. 413.171, because it is furnished to individuals to
treat a condition associated with ESRD and is essential to the
delivery of maintenance dialysis.” The letter informed Ardelyx
that XPHOZAH would be included in the bundled payment for
renal dialysis services beginning January 1, 2025.
C. Procedural History
On July 17, 2024 Ardelyx and the other appellants filed
suit challenging both (1) the CMS’s rule defining “renal
dialysis services” to include oral-only drugs furnished for the
treatment of ESRD, 42 C.F.R. § 413.171(3), and (2) the CMS’s
identification of XPHOZAH as a “renal dialysis service”
included in the bundled payment. Ardelyx alleged these actions
were arbitrary and capricious, an abuse of discretion, not in
accordance with law, violative of statutory right, and in excess
of the CMS’s statutory authority, in violation of the
Administrative Procedure Act, 5 U.S.C. § 706(2)(A), (C). The
CMS moved to dismiss the complaint, arguing that sub-
paragraph (14)(G) deprived the district court of authority to
review the challenged actions. Ardelyx then moved for a

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preliminary injunction or, alternatively, for expedited summary
judgment.
The district court granted the CMS’s motion to dismiss.
Ardelyx I, 757 F. Supp. 3d at 41. The district court first
explained that in order to determine whether the bar to judicial
review in subparagraph (14)(G) precluded it from reviewing
the challenged actions, it had to determine whether the disputed
actions were of the sort subparagraph (14)(B) authorized the
Secretary to take. Id. at 48. The district court concluded they
were.
The court first determined that defining “renal dialysis
services” to include oral-only drugs was an “identification”
within the meaning of the bar to judicial review in subpara-
graph (G), id. at 47, and was consistent with the definition of
“renal dialysis services” in subparagraph (B), id. at 52-56.
Specifically, the district court held that subpart (B)(iii)
“directly incorporates into ‘renal dialysis services’ oral-only
drugs by covering ‘drugs and biologicals,’ other than ESAs,
that were previously reimbursed separately from the bundle.”
Id. at 52. The court also read subparagraph (B), which lists four
types of things included in the definition of “renal dialysis
services,” as providing a non-exhaustive definition of that term.
Id.
The district court next determined the CMS had the
authority to identify XPHOZAH as a “renal dialysis service.”
The district court reasoned that XPHOZAH was furnished “for
the treatment of” ESRD because it treats a condition “caused
by or at least closely associated with kidney disease.” Id. at 58.
Having thus held the CMS had acted within its statutory
authority, the district court did not consider Ardelyx’s other
arguments. Id.

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Ardelyx moved to alter or amend the judgment or, alterna-
tively, for an injunction pending appeal. The district court
denied that motion. Ardelyx, Inc. v. Becerra (Ardelyx II),
No. 24-cv-2095, 2024 WL 5186613 (D.D.C. Dec. 20, 2024).
Ardelyx filed a timely notice of appeal and sought an injunction
pending appeal, which we denied. As a result, the challenged
portion of the rule went into effect on January 1, 2025, and
XPHOZAH was included in the bundled payment.
II. Analysis
We review the district court’s dismissal of Ardelyx’s com-
plaint de novo. See Amgen, Inc. v. Smith, 357 F.3d 103, 108
(D.C. Cir. 2004). On questions of statutory interpretation, this
court “must exercise [its] independent judgment in deciding
whether an agency has acted within its statutory authority.”
Loper Bright Enters. v. Raimondo, 603 U.S. 369, 412 (2024).
A. The Judicial-Review Provision, Subparagraph (14)(G)
Ardelyx challenges the Secretary’s inclusion of oral-only
drugs generally, and XPHOZAH specifically, in the bundled
payment for renal dialysis services. At the outset, we must
determine the scope of our authority to review the challenged
actions. Recall that subparagraph (14)(G) bars judicial review
of “the identification of renal dialysis services included in the
bundled payment.” According to the CMS, we lack the author-
ity to review the challenged actions because they are
“identification[s] of renal dialysis services” within the meaning
of (14)(G). Ardelyx argues that (14)(G) does not cover the
challenged actions because the CMS lacked authority to take
those actions.
“We begin with the strong presumption that Congress
intends judicial review of administrative action.” Bowen v.
Mich. Acad. of Fam. Physicians, 476 U.S. 667, 670 (1986).

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This presumption is “particularly strong” where, as here, a
party claims an agency has acted “in excess of delegated
authority.” Amgen, 357 F.3d at 111. As we have explained, the
Congress “rarely intends to foreclose review of action exceed-
ing agency authority.” Id. at 112. To overcome the
presumption, the party invoking the purported bar to judicial
review must provide “clear and convincing evidence that
Congress intended to preclude the suit.” Id. at 111 (cleaned up);
cf. McLaughlin Chiropractic Assocs., Inc. v. McKesson Corp.,
606 U.S. 146, 159 (2025) (“When Congress wants to bar a
district court in an enforcement proceeding from reviewing an
agency’s interpretation of a statute, Congress can and must say
so”). Most relevant here, the presumption can be overcome by
“specific language” evincing a “congressional intent to
preclude judicial review.” Ascension Borgess Hosp. v. Becerra,
61 F.4th 999, 1003 (D.C. Cir. 2023) (cleaned up).
At first blush, (14)(G) seems to be precisely that. It simply
says there “shall be no administrative or judicial review” of
“the identification of renal dialysis services included in the
bundled payment.” As the district court observed, “[t]his
stripping of judicial review . . . could not be clearer.” Ardelyx
I, 757 F. Supp. 3d at 47.
As the district court also realized, however, the judicial
inquiry does not end there. A “jurisdiction-stripping provision
does not apply if the agency’s action fails to qualify as the kind
of action for which review is barred.” Am. Hosp. Ass’n v. Azar,
964 F.3d 1230, 1238 (D.C. Cir. 2020) (cleaned up).
Consequently, in order “to determine whether the judicial-
review bar applies in this case, we must decide whether the
challenged agency action[s]” are the sort of actions shielded
from review by (14)(G). Id.

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We have previously applied this approach to another bar
to judicial review involving prospective payments under
Medicare. In 42 U.S.C. § 1395l(t)(12)(A), the Congress
provided that “[t]here shall be no administrative or judicial
review” of “the establishment of . . . other adjustments, and
methods described in paragraph 2(F).” In Amgen we consid-
ered whether we had authority to review a challenge to a rule
adjusting certain rates under Medicare Part B. 357 F.3d at 106-
08. The CMS said it made the adjustments under
§ 1395l(t)(2)(E), which authorized it to establish “other
adjustments as determined to be necessary to ensure equitable
payments.” Id. at 107. The CMS argued that subparagraph
(12)(A) barred judicial review of the adjustments. Before
dismissing the complaint, we had first to determine whether the
equitable adjustments authorized by subparagraph (2)(E)
qualified as “other adjustments” for purposes of the bar to
judicial review in (12)(A) and, if so, whether (2)(E) authorized
the Secretary to make the challenged adjustments. Id. at 111.
These determinations were necessary, we explained, because
the bar to judicial review “prevent[ed] review only of those
‘other adjustments’ that the Medicare Act authorizes the
[CMS] to make.” Id. at 112.
Similarly, in American Hospital Association we consid-
ered whether we had authority to review a challenge to a rate
reduction implemented by the Department of Health and
Human Services for a particular outpatient service. 964 F.3d at
1237. The agency had implemented the reduction pursuant to
§ 1395l(t)(2)(F), which authorized it to “develop a method for
controlling unnecessary increases in the volume of covered
[outpatient] services.” Id. at 1235. HHS again invoked the bar
to judicial review in (12)(A), which precludes review of “the
establishment of . . . methods described in paragraph (2)(F).”
Id. at 1237. The agency asked us to “dispose of the case on that
basis at the threshold without examining HHS’s authority to

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implement the rate reduction.” Id. at 1237-38. We declined,
noting that the premise of the plaintiffs’ claim was that the chal-
lenged reduction was “not a ‘method described in paragraph
(2)(F)’ within the meaning of the statute.” Id. at 1238 (cleaned
up). Pursuant to the reasoning in Amgen, we held (12)(A)
barred us from reviewing the reduction only if it “qualified as
a ‘method for controlling unnecessary increases in volume’
under subparagraph (2)(F).” Id. at 1238-39 (cleaned up). We
then proceeded to consider that question. See id. at 1239-45.
The same reasoning applies here. Ardelyx claims the CMS
exceeded its statutory authority by including oral-only drugs,
including XPHOZAH, in the payment bundle. In order to
determine whether we have authority to review Ardelyx’s
claims, we must decide whether the agency’s actions qualify as
an “identification of renal dialysis services” within the mean-
ing of the bar to judicial review in subparagraph (14)(G). This,
in turn, requires us to consider the meaning of “renal dialysis
services” in subparagraph (14)(B).
The CMS insists we need not look past subparagraph
(14)(G) in order to dismiss Ardelyx’s challenge. According to
the CMS, the only question is whether the CMS purported to
identify or to “recognize” a drug as a renal dialysis service,
which it indisputably did in the May 13, 2024 letter to Ardelyx.
Needless to say, the CMS’s authority to include a particular
drug in the bundled payment does not turn upon its say-so.
Indeed, we have previously described this as a “preposterous
position” because a “bald assertion of power by an agency
cannot legitimize it.” COMSAT Corp. v. FCC, 114 F.3d 223,
227 (1997) (cleaned up); see Amgen, 357 F.3d at 113-14
(relying upon COMSAT to determine the scope of the bar to
judicial review); Am. Hosp., 964 F.3d at 1238 (same).
“Otherwise, agencies could characterize reviewable or
unauthorized action as falling within the scope of no-review

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provisions whose application to such action Congress did not
intend.” Amgen, 357 F.3d at 113.
We are also unpersuaded by the CMS’s attempt to distin-
guish the reasoning of Amgen and American Hospital
Association. The CMS claims the bar to judicial review in those
cases expressly cross-referenced another provision, and
reasons that we needed to consider the cross-referenced provi-
sions only to determine the scope of the bar. Because (14)(G)
does not cross-reference any other provision, the agency says,
we need not look elsewhere.
As an initial matter, the CMS’s description of the bar to
judicial review we encountered in Amgen and in American
Hospital Association is not entirely accurate. Although that
provision included a specific cross-reference for “methods,” it
did not include one for “other adjustments” — the term at issue
in Amgen. Even without an applicable cross-reference, we
observed the use of “other adjustments” in the bar to judicial
review “matches the language . . . in § 1395l(t)(2)(E),
implying that Congress intended to reference adjustments
made pursuant to that subsection.” 357 F.3d at 113.
In this case, the CMS’s argument fails for a simpler reason:
The Congress expressly tied the bar to judicial review in
(14)(G) to the definition of “renal dialysis services” in (14)(B)
by defining that term “[f]or purposes of this paragraph” — i.e.,
paragraph (14). As the district court observed, this “obviate[s]
a need for an additional express link in” (14)(G) because that
provision also refers to “renal dialysis services.” Ardelyx I,
757 F.3d at 50. The term “renal dialysis services” has the same
meaning in both provisions, so we must look to the definition
in (14)(B) to determine the scope of (14)(G).
To be sure, this approach may “merge consideration of the
legality of the [agency]’s action with consideration of this

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court’s jurisdiction.” COMSAT, 114 F.3d at 227 (cleaned up).
Here, for example, the question whether the CMS exceeded its
authority by including oral-only drugs and XPHOZAH in the
bundled payment coincides with the question whether each of
those actions qualifies as an “identification of renal dialysis
services.” This inquiry does not, however, render the judicial-
review bar irrelevant. That bar “still forecloses inquiry into
whether the challenged agency decision is arbitrary, capricious,
or procedurally defective.” Am. Hosp., 964 F.3d at 1239
(cleaned up). If the CMS acted within its authority by including
oral-only drugs and XPHOZAH in the bundled payment, then
we lack authority to review whether those actions were
“reasonable and reasonably explained,” as required by the
APA. FCC v. Prometheus Radio Proj., 592 U.S. 414, 423
(2021). We review the merits of Ardelyx’s challenge, there-
fore, only “to the extent necessary to determine whether the
challenged agency actions fall within the scope of the preclu-
sion of judicial review.” Amgen, 357 F.3d at 113 (cleaned up).
B. Ardelyx’s Challenge to the Regulation, 42 C.F.R.
§ 413.171(3)
In this section we consider whether the CMS’s inclusion
of oral-only drugs in the bundled payment constitutes an
“identification of renal dialysis services.” Subparagraph
(14)(G).‡ Recall that the CMS has defined “renal dialysis
services” to include drugs furnished for the treatment of ESRD
that have “only an oral form.” 42 C.F.R. § 413.171(3). Ardelyx
‡ The CMS erroneously implies that Ardelyx’s complaint did not
challenge the regulation defining “renal dialysis services” to include
oral-only drugs. Ardelyx’s complaint plainly challenges
§ 413.171(3). See Compl. ¶¶ 212-15 (arguing the CMS’s
promulgation of § 413.171(3) was “arbitrary, capricious, an abuse of
discretion, not in accordance with law, in excess of statutory
jurisdiction and authority, and short of statutory right”).

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offers two reasons the bar to judicial review does not preclude
its challenge to this aspect of the rule. First, Ardelyx argues the
CMS’s promulgation of the rule was not an “identification” for
purposes of subparagraph (14)(G). Second, Ardelyx claims the
definition of “renal dialysis services” does not include oral-
only drugs, so the CMS lacks authority to include such drugs
in the bundled payment.
1. “Identification”
Ardelyx asserts that an “identification” within the bar to
review in (14)(G) means the selection of a particular drug
rather than a category of drugs. Because 42 C.F.R.
§ 413.171(3) speaks of a category, Ardelyx argues (14)(G)
does not preclude us from reviewing its challenge to the
regulation.
The statute does not define “identification,” so we give
that term its ordinary meaning. Taniguchi v. Kan Pacific
Saipan, Ltd., 566 U.S. 560, 566 (2012). The parties offer sev-
eral definitions of “identify.” The CMS refers us to the Oxford
English Dictionary, which defines to “identify” as to
“recognize as belonging to a particular category or kind.”
Ardelyx points to the Merriam-Webster Dictionary, where to
“identify” means to “state the identity of . . . something,” and
to the Federal Circuit, which has defined to “identify” as to
“recognize or establish an object as being a particular thing,”
Apple Inc. v. Omni MedSci, Inc., No. 2023-1034, 2024 WL
3084509, at *5 (June 21, 2024); see also Ardelyx I, 757 F.
Supp. 3d at 47 (defining to “identify” as to “recognize
something and say or prove what that thing is” (cleaned up)).
Each of these definitions is broad enough to cover the
CMS’s determination that oral-only drugs furnished for the
treatment of ESRD qualify as renal dialysis services. The CMS
has recognized something (oral-only drugs furnished for the

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treatment of ESRD) as being a particular thing or as belonging
to a particular category, namely, renal dialysis services. The
CMS’s promulgation of the regulation thus fits comfortably
within the meaning of “identification” in (14)(G). Nothing in
the statute or in the definitions offered by Ardelyx supports its
narrower reading, which would preclude the CMS from mak-
ing categorical determinations about which drugs to include in
the bundle.
A contrary conclusion would too easily allow a plaintiff to
circumvent subparagraph (G) and challenge the inclusion of a
particular drug in the bundle. As the CMS notes, Ardelyx does
not challenge the regulation “in a vacuum”; it also challenges
the inclusion of XPHOZAH in the bundle “consistent with this
regulation.” Ardelyx does not argue that the May 13, 2024
letter selecting XPHOZAH for the bundle was not an
“identification.” Under Ardelyx’s reading of “identification,”
however, “almost any challenge to an [identification of a
particular drug] could be recast as a challenge to [the]
underlying [regulation],” DCH Reg. Med. Ctr. v. Azar,
925 F.3d 503, 506 (D.C. Cir. 2019), an artful dodge we cannot
allow. Accord Palisades Gen. Hosp. Inc. v. Leavitt, 426 F.3d
400, 405 (D.C. Cir. 2005) (“[W]hen a procedure is challenged
solely in order to reverse an individual . . . decision” covered
by a bar to judicial review, “judicial review is not permitted”).
For this reason, the CMS argues we lack jurisdiction to
consider Ardelyx’s challenge to the regulation because that
challenge is “inextricably intertwined” with the challenge to
the identification of XPHOZAH. Yet Ardelyx raises distinct
arguments as to why each action does not qualify as an
“identification of renal dialysis services.” For example, as just
discussed, Ardelyx argues the CMS’s promulgation of
§ 413.171(3) was not an “identification” for purposes of the bar
to judicial review; it does not raise that argument with respect

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19
to XPHOZAH. Moreover, even if we viewed Ardelyx’s chal-
lenge to the regulation as “inextricably intertwined” with its
challenge to XPHOZAH, we would still have to consider
whether the CMS had authority to include XPHOZAH in the
bundle for the reasons discussed. We therefore consider both
of Ardelyx’s challenges below.
2. “Renal dialysis services”
Ardelyx’s principal challenge to 42 C.F.R. § 413.171(3) is
that the definition of “renal dialysis services” in (14)(B)
excludes oral-only drugs. That subparagraph lists four catego-
ries that the Congress “include[d]” in the definition of “renal
dialysis services.” Ardelyx maintains those categories provide
an exhaustive definition of “renal dialysis services,” and none
of them includes oral-only drugs that are not provided by dial-
ysis facilities during dialysis. The CMS justifies its inclusion
of oral-only drugs in the bundle in three ways. First, it argues
oral-only drugs fit within the definition of “renal dialysis
services” in the third enumerated category, subpart (B)(iii).
Second, it interprets the fourth enumerated category, subpart
(B)(iv), as a catchall provision covering “newly developed
items and services that are not otherwise covered by the prior
[subparts].” Third, it claims it has discretion to include in the
bundle drugs that are not expressly covered by the four catego-
ries in subparagraph (14)(B) because that subparagraph is a
non-exhaustive definition of renal dialysis services. Because
we agree with the agency’s first point, we do not reach its other
arguments.
Subpart (iii) defines “renal dialysis services” to include:
[(1a)] other drugs and biologicals that are
furnished to individuals for the treatment of end
stage renal disease and [(1b)] for which
payment was (before the application of this

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20
paragraph) made separately under this
subchapter, and [(2)] any oral equivalent form
of such drug or biological.
Based upon the plain text of this subpart, we hold the CMS
has the authority to include oral-only drugs in the bundled pay-
ment. The first clause in the subpart establishes two criteria for
inclusion in the definition of a renal dialysis service. The first,
which we have denominated [1a], includes in the definition
“other drugs and biologicals” furnished for the treatment of
ESRD, of which the CMS claims XPHOZAH is one (a matter
we take up later); it does not exclude drugs based upon their
form of administration. Oral-only drugs also satisfy the second
criterion in the first clause [1b] if they were paid for “separately
under this subchapter” and “before the application of this
paragraph.” Id. As the district court said, “‘this subchapter’
refers to Subchapter XVIII, which includes Medicare Parts A,
B, C, and D,” and thus “‘separately under this subchapter’
includes all drugs paid [for] separately under any reimburse-
ment system.” Ardelyx II, 2024 WL 5186613, at *10. Ardelyx
does not challenge that conclusion on appeal. Ardelyx also
acknowledged in its complaint that under the prior payment
system, “orally administered ESRD drugs were generally cov-
ered separately under Medicare Part D.” Compl. ¶ 65.
Therefore, payment for certain oral-only drugs was “made
separately under this subchapter” and “before the application
of” the new bundled payment system. It follows, as the district
court said, that subpart (iii) “directly incorporates” oral-only
drugs in the definition of “renal dialysis services.” Ardelyx I,
757 F. Supp. 3d at 52.
Resisting this conclusion, Ardelyx focuses on the second
clause [2] of subpart (iii), which includes in the definition “any
oral equivalent form of such drug or biological” covered by the
first clause. Ardelyx argues that the express inclusion of oral

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21
drugs in this clause implies the Congress intended to exclude
oral drugs from the first clause.
The CMS rejected this interpretation of the statute as
“unduly constrained.” 74 Fed. Reg. at 49928/3. We agree. The
Congress spoke clearly when it wanted to address drugs admin-
istered in a certain form and when it wanted to omit particular
items from the definition of “renal dialysis services.” It did so
by referring to oral drugs in both subparts (B)(ii) and (B)(iii),
and by expressly excluding vaccines from subparagraph (B).
The Congress did not exclude oral-only drugs from the first
clause of subpart (iii), and we may not read that limitation into
the statute. See Lomax v. Ortiz-Marquez, 140 S. Ct. 1721, 1725
(2020) (“Court[s] may not narrow a provision’s reach by
inserting words Congress chose to omit”); Centro de
Trabajadores Unidos v. Bessent, 167 F.4th 1218, 1231 (D.C.
Cir. 2026) (declining to read “address” to mean “current
address” in a statute authorizing the disclosure of taxpayer
information because the statute did “not specify what address
must be included”).
For similar reasons, we are unpersuaded by Ardelyx’s con-
tention that “renal dialysis services” include only drugs
“provided by dialysis facilities during dialysis.” That limitation
appears nowhere in the subpart (B)(iii) definition of “renal
dialysis services,” which instead refers broadly to drugs
furnished “for the treatment of” ESRD without regard to where
or when they are furnished. In the medical context, “treatment”
means “medical application of remedies so as to effect a cure,”
W EBSTER’ S II DICTIONARY (3rd ed. 2005), and “management
and care to prevent, cure, ameliorate, or slow progression of a
medical condition,” M ERRIAM-W EBSTER DICTIONARY ONLINE .
That definition easily encompasses a drug furnished to treat
ESRD even if it is administered outside of a dialysis treatment.

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22
This reading also accords with the Congress’s intent to bring
more services into the bundled payment.
Ardelyx erroneously contends this reading renders the sec-
ond clause of subpart (iii) superfluous because the first clause
would cover all oral drugs and because there cannot be an “oral
equivalent form” of an oral-only drug. In fact, however, the
first clause covers only drugs furnished to treat
ESRD — regardless the form of administration — that were
separately reimbursed “before the application of” paragraph
(14). The second clause thus brings in any oral equivalent form
of a drug covered by the first clause that became or becomes
available after the application of paragraph (14). If an injecta-
ble drug is covered by the first clause, then the second clause
would cover a subsequently developed oral-equivalent form of
that drug. In those instances, the second clause is not superflu-
ous. That some drugs covered by the first clause will not have
an oral equivalent does not, as Ardelyx suggests, compel a
different reading of the statute. “Language in a statute is not
rendered superfluous merely because in some contexts that
language may not be pertinent.” United States v. Turkette,
452 U.S. 576, 583 n.5 (1981).
In a last gasp, Ardelyx notes that if the Congress had
intended subpart (B)(iii) to include oral-only drugs, then it
could have done so “using far fewer and simpler words.” Per-
haps so, but providing for the inclusion of “other drugs and
biologicals” is one clear and reasonably succinct way of includ-
ing certain drugs regardless of their form of administration.
“[T]he mere possibility of clearer phrasing cannot defeat the
most natural reading of a statute.” Caraco Pharm. Lab’ys, Ltd.
v. Novo Nordisk A/S, 566 U.S. 399, 416 (2012).
We believe subpart (B)(iii) on its face defeats Ardelyx’s
challenge to the regulation. Seeking help elsewhere, Ardelyx

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cites one failed bill introduced in the House of Representatives
that would have expressly added oral-only drugs to subpart
(B)(iii), as though they were not already included in that
subpart. See America’s Affordable Health Choices Act of
2009, H.R. 3200, 111th Cong. § 1232(b)(1). Because the bill
did not pass, Ardelyx believes this shows the Congress did not
intend for subpart (B)(iii) to cover oral-only drugs. “Failed
legislative proposals,” however, “are a particularly dangerous
ground on which to rest an interpretation of a prior statute”
because “several equally tenable inferences may be drawn from
such inaction, including the inference that the existing
legislation already incorporated the offered change.” United
States v. Craft, 535 U.S. 274, 287 (2002) (cleaned up); see also
Knapp Med. Ctr. v. Hargan, 875 F.3d 1125, 1130 (D.C. Cir.
2017) (“We can infer nothing from the Congress’s
consideration and rejection of a differently worded provision
in a separate piece of legislation”).
Subsequent congressional enactments, on the other hand,
have the force of law and reflect the Congress’s understanding
of the pre-existing state of the law. Consequently, these actions
may inform our analysis because “the meaning of one statute
may be affected by other Acts, particularly where Congress has
spoken subsequently and more specifically to the topic at
hand.” FDA v. Brown & Williamson Tobacco Corp., 529 U.S.
120, 133 (2000). Indeed, “it is well established that a court can,
and should, interpret the text of one statute in the light of text
of surrounding statutes, even those subsequently enacted.” Vt.
Agency of Nat. Res. v. United States ex rel. Stevens, 529 U.S.
765, 786 n.17 (2000).
The relevant post-enactment history demonstrates that the
Congress was aware of the CMS’s position regarding oral-only
drugs and subpart (B)(iii) and repeatedly acted in a manner
consistent with that position rather than undermining or

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correcting it. See Brown & Williamson, 529 U.S. at 155-56. As
we have seen in its notice of proposed rulemaking and in the
final rule, issued in 2009 and 2010 respectively, the CMS
interpreted subpart (B)(iii) as including all drugs furnished for
the treatment of ESRD “regardless of the route of
administration.” 74 Fed. Reg. at 49928/3; see 75 Fed. Reg. at
49039/1. Consequently, the final regulation defined “renal
dialysis services” to include “drugs and biologicals with only
an oral form.” 42 C.F.R. § 413.171(3).
Against this backdrop, the Congress passed legislation that
reflected its awareness of the CMS’s position. “When Congress
revisits a statute giving rise to a longstanding administrative
interpretation without pertinent change, the congressional fail-
ure to revise or repeal the agency’s interpretation is persuasive
evidence that the interpretation is the one intended by
Congress.” CFTC v. Schor, 478 U.S. 833, 846 (1986) (cleaned
up).
On three occasions in 2013 and 2014 the Congress
expressly acknowledged the CMS’s inclusion of oral-only
drugs in the bundle without disapproving or amending subpar-
agraph (B). See § 632(b)(1), 126 Stat. at 2354 (2013) (delaying
the implementation of the bundled payment system to oral-only
drugs until January 1, 2016); § 217(a)(1), 128 Stat. at 1061
(2014) (extending the delay until January 1, 2024); and § 204,
128 Stat. at 4065 (2014) (extending the delay until January 1,
2025); see also § 632(a), 126 Stat. at 2354 (amending para-
graph (14) by adding subparagraph (I), which refers to “oral-
only ESRD-related drugs, as such term is used in the final rule
promulgated by the Secretary” (citing 75 Fed. Reg. 49030)). At
the same time, the Congress ordered additional agency action
to collect data on and assess the effect of oral-only drugs and
their treatment of ESRD. See § 632(b)(2), 126 Stat. at 2354
(ordering the CMS to monitor the bone and mineral metabo-

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25
lism in ESRD patients “[w]ith respect to the implementation of
oral-only ESRD-related drugs in the ESRD prospective pay-
ment system”); § 632(d), 126 Stat. at 2354-55 (ordering the
GAO to report on the Secretary’s preparations for adding oral-
only drugs to the bundled payment); § 217(c)(1), 128 Stat. at
1062 (ordering the CMS to “establish a process
for . . . determining when a product is no longer an oral-only
drug” as “part of the promulgation of [the] annual rule for the
Medicare [ESRD] prospective payment system under
[paragraph (14)] for calendar year 2016”); and § 217(d)(3), 128
Stat. at 1062-63 (directing the CMS to establish performance
measures for facilities regarding the quality of patient care
“specific to the conditions treated with oral-only drugs”).
These congressional enactments not only left the CMS’s
definition of “renal dialysis services” unchanged; as the CMS
notes, they would make no sense if the Congress had excluded
oral-only drugs from the definition of “renal dialysis services.”
The only logical conclusion is that the Congress agreed with,
and acted upon the basis of, the CMS’s interpretation of the
statute.
3. “Before the application of this paragraph”
Here we address briefly one remaining dispute regarding
the scope of subpart (B)(iii). The first clause in that subpart
covers a drug only if payment for that drug was made sepa-
rately “before the application of this paragraph.” The district
court concluded that “before the application of this paragraph”
in that provision means before January 1, 2025 for oral-only
drugs such as XPHOZAH because the Congress delayed the
implementation of 42 C.F.R. § 413.171(3) until then. Ardelyx
I, 757 F. Supp. 3d at 53. The CMS seemed to agree with the
district court in its brief in this court, whereas Ardelyx’s brief
argues that approach would create a “nonsensical patchwork”

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26
in which “before the application of this paragraph” takes on a
different meaning based upon a drug’s form of administration:
before January 1, 2011 for non-oral drugs, and before January
1, 2025 for oral-only drugs. Ardelyx also asserts this reading of
the statute would exclude from the bundle several injectable
drugs approved after 2011 that the CMS has included and
would preclude adding to the bundle any oral-only drugs
launched after January 1, 2025. Ardelyx instead suggests
“before the application of this paragraph” means before
January 1, 2011 for all drugs.§
We need not decide the meaning of the disputed phrase.
Despite the differing interpretations before us, we fail to see
how its meaning affects the outcome of this appeal. Recall that
the regulation applies to oral-only drugs “for which payment
was (prior to January 1, 2011) made separately.” § 413.171(3).
If we accept Ardelyx’s position that “before application of this
paragraph” means before January 1, 2011, then the regulation
uses the same date as the statute. If we adopt the district court’s
conclusion that “before the application of this paragraph”
means before January 1, 2025 for oral-only drugs, then the reg-
ulation still works with the statute. As that court observed,
“Any oral-only drug for which payment was made separately
prior to January 2011, per § 413.171(3), is necessarily one for
which payment was made separately . . . before January 1,
2025.” Ardelyx I, 757 F. Supp. 3d at 54. Either way, the CMS
acted within its delegated authority by promulgating the regu-
lation.
§ In a post-argument letter, the CMS offered an alternative interpre-
tation: “at the time that the paragraph is actually applied to any newly
developed drug, ‘payment was . . . made separately under this
subchapter’ for that drug.” We do not address the CMS’s belated
position below.

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If Ardelyx had argued the CMS lacked authority to include
XPHOZAH in the bundle because it was not available before
January 2011, then we would need to resolve the meaning of
“before the application of this paragraph” as applied to oral-
only drugs, including XPHOZAH. Ardelyx did raise that argu-
ment in its motion asking the district court to alter the judg-
ment, but it did not pursue the argument on appeal. Indeed, the
only argument Ardelyx makes with respect to the identification
of XPHOZAH is that the CMS exceeded its authority because
XPHOZAH is not “furnished . . . for the treatment of” ESRD
but rather “to treat hyperphosphatemia,” to the merits of which
we turn below. That argument does not depend on our resolu-
tion of Ardelyx’s objections to the final rule or on the meaning
of “before the application of this paragraph” in subpart (B)(iii).
We therefore have no need to address the precise meaning
of “before the application of this paragraph.” Insofar as the
meaning of this phrase may matter for the identification of any
other drugs as “renal dialysis services,” those drugs are not
before the court.
In sum, we conclude that subpart (B)(iii) defines “renal
dialysis services” to include oral-only drugs furnished for the
treatment of ESRD and for which payment was made sepa-
rately “before the application of [that] paragraph.” Because the
regulation, 42 C.F.R. § 413.171(3), accords with the statutory
definition, subparagraph (14)(G) precludes us from reviewing
the regulation any further.
C. Ardelyx’s Challenge to the Identification of
XPHOZAH
Finally, as just mentioned, Ardelyx challenges the CMS’s
identification of XPHOZAH as a renal dialysis service covered
by the bundled payment. Even if the CMS can include some
oral-only drugs in the bundle, Ardelyx argues, the CMS cannot

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28
include XPHOZAH because it is not furnished for the treat-
ment of ESRD. Again, “XPHOZAH is furnished to treat
hyperphosphatemia, not ESRD.”
Ardelyx relies upon an unduly narrow reading of the
phrase “for the treatment of [ESRD]” in subpart (B)(iii). Con-
sider subpart (B)(ii), which defines “renal dialysis services” to
include “erythropoiesis stimulating agents and any oral form of
such agents that are furnished to individuals for the treatment
of [ESRD].” ESAs treat anemia, a condition often caused by
renal disease. Subpart (B)(ii) thus indicates the Congress
intended the phrase “furnished . . . for the treatment of
[ESRD]” to cover drugs that treat a condition commonly
caused by ESRD. To read that phrase differently in a
neighboring provision would run afoul of the “presumption that
a given term is used to mean the same thing throughout a
statute.” Brown v. Gardner, 513 U.S. 115, 118 (1994).
Also, as we have seen, above at 21, “treatment” as used in
the definition of “renal dialysis services” in (B)(iii) includes the
management and care of a medical condition. That definition
includes not only drugs that treat ESRD specifically but also
drugs such as XPHOZAH that treat conditions closely associ-
ated with ESRD.
Hyperphosphatemia, which is most commonly caused by
ESRD, occurs in 80% of ESRD patients on maintenance dialy-
sis. Of those patients, 70% cannot maintain their target phos-
phate levels with phosphate binders. This is where XPHOZAH
comes in.
As the CMS emphasizes, XPHOZAH’s only approved use
is to treat hyperphosphatemia “in adults with chronic kidney
disease (CKD) on dialysis as add-on therapy in patients who
have an inadequate response to phosphate binders or who are
intolerant of any dose of phosphate binder therapy.” Indeed,

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Ardelyx itself said in a declaration supporting its motion for a
preliminary injunction that XPHOZAH is “approved as an add-
on therapy for patients with ESRD on maintenance dialysis.” It
is therefore unsurprising that even Ardelyx describes
XPHOZAH, in that same declaration, as a “treatment option”
for patients with ESRD on dialysis who experience an inade-
quate response to phosphate binders.
Finally, Ardelyx claims the CMS’s identification of
XPHOZAH “is at odds” with its exclusion of other drugs that
treat conditions commonly associated with or caused by ESRD.
This argument goes to the quality of the CMS’s reasoning
rather than the scope of its authority. Per subparagraph (14)(G),
therefore, we lack jurisdiction to consider it.
III. Conclusion
For the foregoing reasons, the district court order
dismissing Ardelyx’s complaint is
Affirmed.

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