United States Patent 10,864,199: Tacrolimus Extended-Release Patent Scope, Envarsus XR Coverage, and Patent Landscape
US Patent No. 10,864,199 protects treatment methods using once-daily, colon-targeted extended-release tacrolimus for kidney-transplant patients. The independent claims are directed to clinical administration, not merely to a tablet composition. The core limitations are evening or unrestricted-time dosing, substantially colonic release, a substantially zero-order release profile, defined dissolution thresholds, and, in certain claims, conversion from immediate-release tacrolimus at a 20% to 34% dose reduction.
The patent is closely aligned with Envarsus XR, the once-daily extended-release tacrolimus product marketed by Veloxis Pharmaceuticals, a Chiesi Group company. The principal commercial risk is an abbreviated new drug application that uses a formulation and dosing regimen meeting the claimed dissolution, release-site, and conversion limitations. Immediate-release tacrolimus products do not automatically practice these claims.
What drug and product does US Patent 10,864,199 cover?
US 10,864,199 covers methods of suppressing kidney rejection with extended-release tacrolimus administered orally once daily. The claims map most directly to Envarsus XR, whose active ingredient is tacrolimus and whose FDA-approved labeling specifies once-daily administration for prophylaxis of organ rejection in kidney transplant recipients.[1]
| Patent element |
Claimed requirement |
Commercial relevance |
| Active ingredient |
Tacrolimus |
Envarsus XR, Prograf, Astagraf XL and generic tacrolimus products |
| Dosage form |
Extended-release pharmaceutical composition |
Excludes ordinary immediate-release tacrolimus unless used in a qualifying combination |
| Administration |
Oral, once daily |
Matches Envarsus XR labeling |
| Timing |
Evening for claim 1; unrestricted time for claim 14 |
Creates separate infringement pathways |
| Release site |
Substantially in the colon |
Narrows the claims to a specific in vivo delivery behavior |
| Release profile |
Substantially zero-order |
Requires relatively controlled release over time |
| Dissolution |
At least 8% by 4 hours; 40% by 10-14 hours; less than 62% by 15 hours |
Provides a measurable formulation-screening limitation |
| Patient population |
Kidney transplant patients |
Does not expressly cover liver, heart or lung transplantation |
| Clinical purpose |
Suppression of kidney rejection |
Method-of-use limitation |
| Conversion |
Immediate-release to extended-release tacrolimus at a 1:0.66-0.80 ratio |
Directly addresses product switching |
The patent therefore covers a combination of product characteristics and treatment conduct. A competing product must be evaluated against the full claim, including the pharmacokinetic and dissolution limitations.
What are the independent claims in US Patent 10,864,199?
Claims 1, 14 and 17 are the principal independent claims.
Claim 1: evening administration
Claim 1 requires:
- A kidney transplant patient;
- Treatment to suppress kidney rejection;
- Oral administration once daily in the evening;
- An extended-release tacrolimus composition;
- Substantially colonic in vivo release;
- A modifying release agent;
- A substantially zero-order release profile; and
- The specified USP II dissolution profile.
This is a narrow method claim. It does not cover every once-daily tacrolimus formulation. It requires both the claimed release behavior and evening administration.
Claims 2 through 13 add narrower limitations involving the ascending, transverse or descending colon; plasma tacrolimus concentrations of approximately 5 to 20 ng/mL for at least 24 hours; administration for at least seven days; dose ranges; fasting administration; de novo kidney transplantation; and hydrophilic vehicles such as poloxamer or polyethylene glycol.
Claim 14: administration without time-of-day restriction
Claim 14 removes the evening requirement but adds two prescribing limitations:
- The drug is administered once daily without restriction as to time of day; and
- The product was prescribed without restriction as to time of day.
This claim is commercially significant because a generic label or physician-directed regimen that permits administration at any time could potentially satisfy the timing element, assuming the formulation and dissolution limitations are also met.
The claim does not require that administration occur in the evening. A product label that states "take once daily at the same time each day" may require careful analysis because the patent claim addresses both the absence of a time-of-day restriction and the prescription instruction.
Claim 17: conversion from immediate-release tacrolimus
Claim 17 covers switching a kidney transplant patient from immediate-release oral tacrolimus to extended-release tacrolimus. The conversion ratio is central:
[
\text{Immediate-release daily dose} : \text{Initial extended-release daily dose} = 1 : 0.66-0.80
]
The practical effect is an initial extended-release dose equal to 66% to 80% of the prior immediate-release daily dose. Claim 18 narrows the ratio to 1:0.80. Claim 19 adds administration without simultaneous food intake.
For example, conversion from 5 mg per day of immediate-release tacrolimus to 4 mg per day of extended-release tacrolimus falls within the 1:0.80 ratio in claim 18. Conversion to 3.5 mg per day falls within the broader 1:0.66-0.80 range in claim 17.
How narrow are the dissolution limitations?
The dissolution limitations are among the most important claim constraints:
| Time point |
Required release |
| Within 4 hours |
At least 8% w/w |
| Within 10 to 14 hours |
At least 40% w/w |
| Within 15 hours |
Less than 62% w/w |
The test uses:
- USP II Paddle apparatus;
- 50 rpm, described in the supplied claim text as 50 ppm;
- 900 mL aqueous dissolution medium;
- pH 4.5; and
- 0.005% hydroxypropylcellulose.
A product that releases 62% or more by 15 hours would fail that express limitation, even if its overall pharmacokinetic performance resembles Envarsus XR. Conversely, a product that meets the dissolution profile but does not release substantially in the colon may avoid literal infringement, subject to infringement under the doctrine of equivalents.
The claim language creates several technical issues:
- "At least 8%" is an open lower boundary.
- "Less than 62%" is a strict upper boundary.
- "40% within 10 to 14 hours" requires analysis of the relevant testing interval.
- The test medium and apparatus are claim limitations, not merely quality-control preferences.
- Batch-to-batch variability can affect infringement analysis.
- A formulation may meet the in vitro profile while failing the in vivo colonic-release limitation, or the reverse.
What formulations are protected by US 10,864,199?
Claims 10 through 13 identify hydrophilic or water-miscible vehicles. Claim 11 lists polymers and excipients including polyethylene glycol, poloxamer, hydroxypropyl methylcellulose, hydroxypropyl cellulose, methylcellulose, sodium carboxymethylcellulose, pectin, cyclodextrin, alginate, carrageenan and xanthan gum.
Claim 12 specifically covers poloxamer. Claim 13 covers a polyethylene glycol and poloxamer mixture.
These claims are dependent method claims. The vehicle limitation does not independently protect a composition containing one of those excipients. The composition must still be used in the claimed kidney-transplant treatment method and must satisfy the parent claim's release and dissolution requirements.
From a design-around perspective, changing the vehicle may not avoid the independent claims. A competitor would need to examine whether the alternative vehicle still produces:
- Substantially colonic release;
- A substantially zero-order profile; and
- The specified dissolution results.
A formulation change that removes poloxamer may avoid claims 12 and 13 but remain within claim 1, claim 14 or claim 17.
When does US Patent 10,864,199 lose exclusivity?
The patent issued on December 15, 2020. Its effective expiration date is tied to the earliest applicable nonprovisional priority date and any patent-term adjustment or patent-term extension reflected in the USPTO record.[2]
The patent belongs to the Envarsus XR patent family associated with earlier Veloxis tacrolimus development work. Public patent-family records identify a priority chain reaching back to the early 2010s. On that basis, the ordinary 20-year patent term is expected to place expiration in the early 2030s, subject to the specific patent-term-adjustment calculation.
FDA marketing exclusivity is separate from patent life. Envarsus XR received FDA approval in 2015 and is not protected by biologic exclusivity. Any generic launch date depends on the full Orange Book patent set, Paragraph IV litigation, settlement terms and the applicant's certification strategy.[1][3]
| Milestone |
Date or status |
| Envarsus XR FDA approval |
July 2015 |
| US 10,864,199 issuance |
December 15, 2020 |
| Patent term basis |
20 years from applicable earliest nonprovisional priority filing |
| Expected patent-life window |
Early 2030s, subject to USPTO term adjustment |
| Regulatory pathway for competitors |
ANDA, not biosimilar |
| Product type |
Small-molecule tacrolimus extended-release tablet |
What is the Orange Book status of US 10,864,199?
The Orange Book must be checked at the product level because a patent can be listed for Envarsus XR without every listed claim covering every possible tacrolimus product.[3]
The relevant inquiry is whether US 10,864,199 is listed against the applicable Envarsus XR strength and whether the listing remains active. If listed, an ANDA applicant seeking approval before the relevant patent expiration generally must provide a Paragraph IV certification or wait for patent expiry, depending on the certification basis and the applicant's strategy.
A listed method-of-use patent can be addressed through a section viii statement if the applicant can carve out the patented use. That strategy is more difficult where the label's central indication, dosing instruction or conversion instruction falls within the patented method.
For this patent, the most important regulatory question is whether the approved generic label would include:
- Once-daily administration of an equivalent extended-release tacrolimus product;
- Kidney-transplant rejection prophylaxis;
- A conversion instruction from immediate-release tacrolimus;
- A dose-reduction range of 0.66 to 0.80; or
- Administration instructions that match the claimed time-of-day limitations.
Which companies are challenging Envarsus XR patents?
Envarsus XR patent challenges would normally arise through ANDA filings by generic drug manufacturers. Publicly reported litigation involving Envarsus XR has included challenges to the broader Veloxis patent estate, rather than necessarily to every patent in the family.
A Paragraph IV challenge is not equivalent to a finding that a patent is invalid or not infringed. The litigation sequence generally includes:
- ANDA filing with a Paragraph IV certification;
- Notice to the patent owner and NDA holder;
- Patent litigation under the Hatch-Waxman Act;
- A 30-month FDA approval stay, where applicable;
- Possible settlement or license; and
- FDA approval subject to the litigation outcome and regulatory status.
The principal commercial holders are Veloxis Pharmaceuticals A/S and Chiesi Farmaceutici S.p.A. Generic manufacturers with immediate-release tacrolimus products are not automatically positioned to launch a generic Envarsus XR product. Extended-release formulation development, bioequivalence and patent certification are separate requirements.
What patent litigation and settlement risks affect the patent?
The highest-risk disputes would concern claim construction and factual testing rather than the identity of tacrolimus itself.
Likely litigation issues
| Issue |
Legal significance |
| "Substantially in the colon" |
Requires interpretation of the in vivo release-location limitation |
| "Substantially zero order" |
Raises questions about the acceptable release-rate deviation |
| Dissolution thresholds |
Can be tested using accused-product batches |
| "Modifying release agent" |
May be construed broadly or narrowly based on the specification |
| Prescribed without restriction as to time of day |
May turn on the generic label and prescribing instructions |
| 1:0.66-0.80 conversion ratio |
Creates a direct label-based infringement theory |
| Method-of-treatment limitation |
Requires proof of intended use, label content or actual use |
A settlement could provide a delayed generic entry date, a license limited to certain strengths, or a carve-out for noninfringing indications or dosing instructions. A settlement that permits an authorized generic or licensed generic may materially change the commercial value of the patent estate even if the patent remains valid.
No biosimilar pathway applies. Tacrolimus is a small molecule, so competitors must use the ANDA or, in some cases, a full NDA pathway.
How strong is the patent estate for Envarsus XR?
The estate has meaningful strength because it combines several protection layers:
- Composition and formulation patents;
- Extended-release and colon-targeting technology;
- Dissolution-profile limitations;
- Kidney-transplant method-of-use claims;
- Dose-conversion claims; and
- FDA-listed patents that can delay or complicate ANDA approval.
Its principal weakness is claim specificity. The asserted product must satisfy multiple limitations simultaneously. A generic applicant may seek to design around the estate by changing the release mechanism, dissolution profile, vehicle, dosing instructions or conversion language.
The estate is strongest where the generic product is intentionally designed to reproduce Envarsus XR's clinical performance and label. It is weaker against a product that achieves extended release through a different mechanism and uses a label that omits the patented conversion regimen.
How does US 10,864,199 compare with immediate-release tacrolimus and Astagraf XL?
| Product |
Release type |
Typical dosing |
Relationship to US 10,864,199 |
| Prograf/generic tacrolimus |
Immediate release |
Usually twice daily |
May be relevant only as the prior treatment in conversion claims |
| Envarsus XR |
Extended release tablet |
Once daily |
Closest commercial product to the claimed methods |
| Astagraf XL |
Extended-release capsule |
Once daily |
May avoid claims if its release site, dissolution profile or formulation does not meet the limitations |
| Generic extended-release tacrolimus |
Product-specific |
Once daily |
Requires product-by-product claim and Orange Book analysis |
The patent does not cover all extended-release tacrolimus products merely because they are once daily. The release location and dissolution profile are critical differentiators.
What generic launch scenarios exist?
Scenario 1: Paragraph IV challenge with litigation
A generic applicant challenges the listed patent and seeks approval before expiration. Launch depends on litigation, settlement and any applicable 30-month stay.
Scenario 2: Section viii carve-out
The applicant removes patented conversion or dosing instructions from the label. This strategy may be difficult if the remaining label still directs once-daily administration for kidney-transplant rejection prophylaxis.
Scenario 3: Noninfringing extended-release formulation
A competitor develops a product with a different dissolution profile or non-colonic release mechanism. It would still need to establish bioequivalence and obtain FDA approval.
Scenario 4: Post-expiration launch
A generic waits until the relevant Orange Book patent protections expire. This avoids Paragraph IV litigation but delays market entry.
Revenue exposure is concentrated in Envarsus XR because the patent is tied to the product's key commercial attributes: once-daily administration, reduced exposure relative to immediate-release conversion, and controlled tacrolimus delivery. The financial impact of generic entry would depend on the number of approved competitors, authorized-generic strategy, payer substitution and the status of other Envarsus XR patents.
Key Takeaways
- US 10,864,199 is a method patent centered on once-daily extended-release tacrolimus for kidney-transplant patients.
- Claim 1 requires evening dosing, while claim 14 permits administration without a time-of-day restriction.
- Claim 17 covers conversion from immediate-release tacrolimus at a 66% to 80% initial extended-release dose.
- The claimed product must release substantially in the colon and meet a detailed USP II dissolution profile.
- Envarsus XR is the closest commercial product to the claimed methods.
- Immediate-release tacrolimus products do not automatically infringe.
- Tacrolimus is a small molecule, so biosimilar analysis is inapplicable.
- The principal competitive risks are Paragraph IV challenges, label carve-outs, alternative extended-release technologies and post-expiration generic entry.
- The patent's expected life extends into the early 2030s, subject to the official USPTO patent-term calculation and the broader Orange Book estate.
FAQs About US Patent 10,864,199
Does US 10,864,199 cover all once-daily tacrolimus products?
No. The claims require specific in vivo release, dissolution and clinical-use limitations. A once-daily product with a different release profile may avoid infringement.
Does switching from Prograf to an extended-release tacrolimus product infringe the patent?
It may, if the switch uses the claimed 1:0.66-0.80 dose ratio and the extended-release product meets the claimed release and dissolution limitations.
Can a generic manufacturer omit the patented conversion language?
Potentially. A section viii label carve-out may be available if the patented method can be removed without retaining instructions that practice the claimed use. The feasibility depends on the FDA-approved reference label and the full Orange Book listing.
Is Astagraf XL automatically covered by US 10,864,199?
No. Astagraf XL requires a separate comparison of its formulation, release site, dissolution results, labeling and prescribed dosing instructions against each claim limitation.
What is the most important technical test for an accused product?
The decisive screening test is the claimed USP II dissolution profile, combined with evidence regarding substantially colonic in vivo release. Meeting only one of those requirements is not enough for literal infringement.
References
- U.S. Food and Drug Administration. (2015). Envarsus XR (tacrolimus extended-release tablets) prescribing information.
- United States Patent and Trademark Office. (2020). U.S. Patent No. 10,864,199, Extended release tacrolimus formulations and methods of use.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book.
