US Patent 10,548,846: Scope, Claims, Expiration, and Biktarvy Patent Landscape

US Patent 10,548,846 protects a specific multilayer tablet containing bictegravir, tenofovir alafenamide, and emtricitabine, corresponding to the active pharmaceutical combination in Biktarvy. Its strongest protection is directed to the formulation architecture: a bictegravir-containing first layer, an emtricitabine/tenofovir alafenamide second layer, defined salt forms, narrow dose amounts, and a tablet weight below specified thresholds. The patent does not broadly claim bictegravir, tenofovir alafenamide, emtricitabine, or the treatment of HIV as standalone inventions.

The patent issued on February 25, 2020, from an application claiming priority to a 2016 filing. Its ordinary 20-year patent term is expected to run into 2036, subject to any patent-term adjustment, terminal disclaimer, or other USPTO term determination. The principal commercial product implicated by the claims is Biktarvy, marketed by Gilead Sciences.

What drug and formulation does US Patent 10,548,846 protect?

The patent protects a fixed-dose combination tablet containing:

Component	Claimed amount	Commercial relevance
Bictegravir or a pharmaceutically acceptable salt	50 mg active-equivalent amount	Integrase strand transfer inhibitor
Tenofovir alafenamide or a pharmaceutically acceptable salt	25 mg active-equivalent amount	Nucleotide reverse transcriptase inhibitor
Emtricitabine or a pharmaceutically acceptable salt	200 mg	Nucleoside reverse transcriptase inhibitor
Tablet structure	Multilayer tablet	Separates formulation components
Tablet weight	Less than about 1,000 mg in claim 1	Controls dosage-form size

The compound identified as Formula I is bictegravir. Formula II is the bictegravir salt used in the more specific formulation claims, principally bictegravir sodium. The commercial Biktarvy tablet contains bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate, with labeled strengths of 50 mg, 200 mg, and 25 mg, respectively. The patent claims the pharmaceutical salt quantities corresponding to those active amounts. (Gilead Sciences, Inc., 2020; U.S. Food and Drug Administration [FDA], 2024)

How broad is claim 1 of US Patent 10,548,846?

Claim 1 is the principal broad composition claim. It requires all of the following:

A multilayer tablet.
50 mg of bictegravir or a pharmaceutically acceptable salt.
25 mg of tenofovir alafenamide or a pharmaceutically acceptable salt.
200 mg of emtricitabine or a pharmaceutically acceptable salt.
A total tablet weight below about 1,000 mg.

The claim is formulation-specific rather than molecule-specific. A product containing the same three active ingredients in a capsule, monolithic tablet, powder, suspension, or tablet exceeding the specified weight would not literally satisfy every limitation of claim 1.

The claim does not require:

A specific excipient system.
A particular coating.
A specific manufacturing process.
A particular dissolution profile.
A stated HIV treatment indication.
A specific ratio of excipients.
A specific layer weight.
Bictegravir sodium or tenofovir alafenamide hemifumarate, unless a narrower claim is asserted.

The phrase “about 1,000 mg” introduces a claim-construction issue. The legally relevant boundary would depend on the intrinsic patent record, prosecution history, technical context, and evidence concerning manufacturing and measurement variability.

What do claims 2 through 8 add?

Claims 2 through 8 progressively narrow the formulation.

Claim	Additional limitation	Practical effect
2	Salt forms for bictegravir and tenofovir alafenamide; emtricitabine remains specified	Narrows chemical form
3	52 mg bictegravir sodium and 28 mg tenofovir alafenamide hemifumarate	Targets pharmaceutical salt weights corresponding to labeled active doses
4	Total weight below about 800 mg	Narrows dosage-form size
5	Total weight below about 730 mg	More closely tracks the disclosed commercial-style tablet
6	Bictegravir component below about 15% of tablet weight	Adds a concentration limitation
7	Bictegravir component below about 11% of tablet weight	More restrictive concentration limitation
8	Coated tablet	Excludes uncoated tablets from the dependent claim

Claims 4 and 5 are commercially important because they target a compact tablet. Claim 9 discloses a formulation with a calculated uncoated core weight of 700.2 mg:

First layer: 52.5 mg bictegravir sodium-related compound + 246.3 mg microcrystalline cellulose + 19.4 mg croscarmellose sodium + 4.9 mg magnesium stearate = 323.1 mg.
Second layer: 200 mg emtricitabine + 28 mg tenofovir alafenamide hemifumarate + 113.2 mg microcrystalline cellulose + 30.2 mg croscarmellose sodium + 5.7 mg magnesium stearate = 377.1 mg.
Total core: 700.2 mg, before film coating.

That formulation falls below the approximately 730 mg limitation in claim 5 if the relevant calculation includes the core and the coating does not move the finished tablet above the applicable threshold.

What formulation is protected by claim 9?

Claim 9 is a highly detailed formulation claim. It requires:

First layer

52.5 mg of the Formula II compound.
246.3 mg microcrystalline cellulose.
19.4 mg croscarmellose sodium.
4.9 mg magnesium stearate.

Second layer

200 mg emtricitabine.
28 mg tenofovir alafenamide hemifumarate.
113.2 mg microcrystalline cellulose.
30.2 mg croscarmellose sodium.
5.7 mg magnesium stearate.

Additional requirement

A film coating.

Unlike claim 1, claim 9 is not merely a dose-and-weight claim. It requires the stated ingredients in the stated layers and approximately the stated quantities. The claim creates potential design-around opportunities through changes to:

The excipient quantities.
The excipient identity.
The layer allocation.
The salt form.
The coating system.
The amount of one or more active ingredients.

The scope of such changes would depend on claim construction, including the meaning of “comprising,” numerical tolerance, and whether a modified formulation remains within the claimed ranges or is equivalent to the claimed composition.

What does claim 10 add to the formulation protection?

Claim 10 requires physical segregation of the active ingredients:

The first layer contains bictegravir sodium-related material and is substantially free of tenofovir alafenamide.
The second layer contains tenofovir alafenamide hemifumarate and emtricitabine and is substantially free of bictegravir.
The claim depends on the 52 mg bictegravir-salt and 28 mg tenofovir-alafenamide-salt formulation.

This limitation is directed to a bilayer architecture in which bictegravir is separated from the tenofovir alafenamide/emtricitabine layer. The “substantially free” language may create factual disputes over trace levels, cross-contamination, manufacturing carryover, and the amount needed to affect formulation performance.

Claim 10 is narrower than claim 1 but may be more commercially relevant because it maps onto the physical organization of a Biktarvy-type tablet.

When does US Patent 10,548,846 lose exclusivity?

The patent issued from a priority chain beginning in 2016. Based on a standard 20-year term measured from the earliest effective nonprovisional filing, the expected nominal expiration is in 2036. The precise expiration date must be taken from the USPTO patent-term calculation because patent-term adjustment can extend the term and a terminal disclaimer can limit it. (U.S. Patent and Trademark Office [USPTO], 2024)

FDA regulatory exclusivity is separate from patent protection. Biktarvy was approved in 2018 under NDA 210251. Small-molecule new chemical entity exclusivity generally lasts five years, subject to the statutory rules governing paragraph IV filings and other exclusivity periods. That regulatory period does not extend the patent term. (FDA, 2024; 21 U.S.C. § 355)

The relevant commercial sequence is therefore:

Event	Date or period
Biktarvy FDA approval	2018
Five-year NCE exclusivity period	Generally through 2023, subject to statutory calculations
US Patent 10,548,846 issuance	February 25, 2020
Expected ordinary patent-term endpoint	2036, subject to USPTO adjustment
Potential generic entry	Controlled by Orange Book patents, litigation, settlements, and court outcomes

What is the Orange Book status of US Patent 10,548,846?

Patent 10,548,846 is associated with the Biktarvy fixed-dose combination and is relevant to FDA-listed patent protection for the product. The Orange Book analysis should distinguish between:

Patents listed for the approved drug.
Patent claims covering the active ingredient.
Formulation patents.
Method-of-use patents.
The use codes and expiration dates submitted by the NDA holder.
Any delisting, expiry, or correction entered by FDA.

A generic applicant filing an ANDA for a product that references Biktarvy would evaluate each listed patent. A paragraph IV certification could allege that the patent is invalid, unenforceable, or not infringed. The filing of a paragraph IV notice can trigger patent litigation and, if suit is filed within the statutory period, a 30-month stay of final FDA approval under the Hatch-Waxman framework. (FDA, 2023; 21 U.S.C. § 355(j)(5)(B)(iii))

Patent 10,548,846 is most relevant to a generic that uses:

The same three active ingredients.
The same bilayer or multilayer structure.
The same or materially similar salt forms.
A tablet weight below 1,000 mg, 800 mg, or 730 mg.
A bictegravir-containing first layer.
A tenofovir alafenamide/emtricitabine second layer.

What paragraph IV challenges could target this patent?

A paragraph IV challenge could attack the patent on several grounds.

Anticipation

A challenger would need to identify a single prior-art reference disclosing every required element of the asserted claim, including:

The three active ingredients.
The claimed doses.
The multilayer tablet.
The tablet-weight limitation.
The relevant salt forms or formulation details.

Claims 9 and 10 are harder to anticipate because they require exact or highly specific layer compositions.

Obviousness

Obviousness is the more likely technical challenge. A challenger could argue that a skilled formulator would have combined known bictegravir, emtricitabine, and tenofovir alafenamide products into a compact multilayer tablet. The patent holder would likely rely on formulation constraints, stability, compatibility, manufacturability, tablet size, and the claimed separation of ingredients to support nonobviousness.

Written description and enablement

The challenger could question whether the specification adequately supports the full breadth of claim 1 across all pharmaceutically acceptable salts, excipients, coatings, and tablet constructions below 1,000 mg. The detailed examples strengthen claims 9 and 10 but may not necessarily support every embodiment covered by broader claim 1.

Indefiniteness

Potential claim-construction issues include:

“About 1,000 mg.”
“About 800 mg.”
“About 730 mg.”
“Less than about 15%.”
“Less than about 11%.”
“Substantially free.”

These terms are common in pharmaceutical patent claims, but their enforceability depends on whether the specification and prosecution history provide objective boundaries.

What patent landscape surrounds Biktarvy and bictegravir?

Patent 10,548,846 is one part of a broader Biktarvy estate. The commercial risk analysis should separate four categories:

Patent category	Subject matter	Relevance
Bictegravir compound patents	Chemical compound and salts	May block manufacture or use of bictegravir itself
Combination patents	Bictegravir with emtricitabine and tenofovir alafenamide	Protect the fixed-dose combination
Formulation patents	Bilayer structure, excipients, salt forms, tablet weight	Directly relevant to a Biktarvy-style generic
Method-of-use patents	HIV treatment and dosing regimens	May affect labeling and skinny-label strategy

The ’846 patent is principally a formulation and combination patent. It does not replace any broader patent protection covering bictegravir as a chemical entity. A generic applicant therefore would need to assess the entire Orange Book-listed estate, not only this patent.

Does biosimilar risk apply to Biktarvy?

No. Biktarvy is a small-molecule drug product, not a biologic. The relevant competitive pathway is an ANDA under Hatch-Waxman, not a 351(k) biosimilar application. The key entry mechanisms are paragraph III certifications, paragraph IV certifications, patent expiration, litigation settlements, and potential authorized-generic strategies.

What generic launch scenarios exist?

Three scenarios are commercially relevant:

A delayed launch after patent expiry. The generic enters after the applicable patent barriers expire or are otherwise removed.
An at-risk launch after a paragraph IV challenge. The applicant launches before final resolution and accepts potential damages or injunctive risk.
A settlement-based launch. The generic receives a negotiated entry date, potentially with terms governing launch timing, manufacturing, or authorized supply.

The ’846 patent creates the highest infringement exposure for a generic that copies the Biktarvy bilayer structure and uses the claimed salt and weight parameters. A materially different formulation may reduce literal infringement risk but can still encounter other patents in the bictegravir and Biktarvy estate.

How strong is the patent estate for US Patent 10,548,846?

The estate has mixed strength by claim category.

Claim group	Relative scope	Commercial strength
Claim 1	Broad combination and multilayer tablet claim	Strongest breadth, greater obviousness exposure
Claims 2-8	Salt, weight, concentration, coating limitations	Narrower but more product-specific
Claim 9	Exact excipient and layer formulation	Strong product mapping, limited design-around reach
Claim 10	Layer segregation and “substantially free” limitations	Strong structural relevance, possible construction disputes

The patent is most valuable against a copycat tablet that reproduces the Biktarvy dosage strengths, bilayer organization, compact tablet size, and salt forms. Its value is lower against a generic using a different dosage form, a different layer arrangement, substantially different excipients, or a different tablet weight.

Key Takeaways

US Patent 10,548,846 is directed to a bictegravir/emtricitabine/tenofovir alafenamide multilayer tablet.
The claims correspond closely to the Biktarvy fixed-dose combination.
Claim 1 requires the three active ingredients, a multilayer tablet, and a total weight below about 1,000 mg.
Claims 3 through 10 progressively target bictegravir sodium, tenofovir alafenamide hemifumarate, compact tablet weights, coatings, exact excipient quantities, and layer segregation.
Claim 9 specifies a 700.2 mg uncoated core formulation before film coating.
Claim 10 requires bictegravir and the emtricitabine/tenofovir alafenamide combination to occupy separate layers.
The expected nominal patent term runs into 2036, subject to the USPTO’s final term calculation.
The patent is relevant to ANDA paragraph IV analysis, not biosimilar litigation.
The main validity risks are obviousness, written description, enablement, and construction of “about” and “substantially free.”
A generic may reduce exposure by changing the layer structure, excipients, salt forms, tablet weight, or dosage form, but it must evaluate the full Biktarvy patent estate.

FAQs about US Patent 10,548,846

Does US Patent 10,548,846 claim Biktarvy by name?

No. The patent claims the active ingredients, salt forms, doses, tablet structure, weight, and formulation characteristics that correspond to Biktarvy. It does not need to use the Biktarvy trademark to cover a product meeting the claim limitations.

Is claim 9 limited to the exact listed excipient quantities?

Yes, claim 9 is materially narrower than claim 1 and recites specified amounts of microcrystalline cellulose, croscarmellose sodium, and magnesium stearate in defined layers. The legal effect of numerical deviations depends on claim construction and potential equivalents analysis.

Can a generic avoid claim 10 by mixing all three drugs in one layer?

That may avoid the literal requirement that the active ingredients be segregated into separate layers, but it would not resolve exposure under other patents or claims. The full product and patent estate must be analyzed.

Is tenofovir alafenamide hemifumarate the same as tenofovir alafenamide?

No. Tenofovir alafenamide is the active moiety. The hemifumarate is a pharmaceutical salt form used to deliver the claimed active amount. Claims 3, 9, and 10 distinguish the salt quantity from the labeled active-equivalent dose.

Does patent expiration automatically permit immediate generic launch?

No. Launch timing also depends on other unexpired patents, FDA approval, statutory exclusivity, litigation outcomes, settlements, regulatory requirements, and any applicable court order.

References

Gilead Sciences, Inc. (2020). Pharmaceutical compositions comprising bictegravir, emtricitabine, and tenofovir alafenamide, U.S. Patent No. 10,548,846. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2024). Biktarvy prescribing information. U.S. Department of Health and Human Services.
U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation guidance. U.S. Department of Commerce.
Hatch-Waxman Amendments, 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Gilead Sciences Inc	BIKTARVY	bictegravir sodium; emtricitabine; tenofovir alafenamide fumarate	TABLET;ORAL	210251-001	Feb 7, 2018		RX	Yes	Yes	10,548,846	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	106645	⤷ Start Trial
Australia	2016354007	⤷ Start Trial
Australia	2020200995	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,548,846

Which drugs does patent 10,548,846 protect, and when does it expire?

Summary for Patent: 10,548,846