United States Patent 6,315,720: Scope, Claims, Expiration, and Thalidomide Patent Landscape

U.S. Patent No. 6,315,720 covered a computer-controlled drug-distribution method that assigned patients to risk groups, collected safety information, determined whether treatment risk was acceptable, and generated a pharmacy approval code. Claims 22-27 narrowed the method to thalidomide, pregnancy testing, fetal-risk controls, and prescriptions limited to approximately 28 days. Claims 28-32 addressed adverse effects caused by drug combinations.

The patent was assigned to Celgene Corporation and expired in 2019. It no longer blocks generic thalidomide distribution or current FDA risk-management programs. Its principal commercial importance was historical: it helped protect the operating model behind Celgene's thalidomide distribution program, commonly associated with the S.T.E.P.S. system.

What does U.S. Patent 6,315,720 cover?

The patent claims a restricted distribution and prescribing workflow, not thalidomide itself, a thalidomide formulation, or a manufacturing process.

The core architecture requires:

A prescriber registered in a computer-readable database.
A pharmacy registered and qualified to dispense the drug.
A patient registered and approved to receive the drug.
Risk groups defined using predetermined drug-specific parameters.
Patient information collected to evaluate adverse-event risk.
Assignment of the patient to one or more risk groups.
A determination that the risk is acceptable.
Generation of an approval code that the pharmacy retrieves before dispensing.

The claims are therefore directed to a controlled drug-delivery system implemented through patient-risk classification and pharmacy authorization.

Claim structure

Claim group	Subject matter	Practical scope
Claims 1-6	Core risk-group, consent, registration, and approval-code method	Broadest general method claims
Claims 7-10	Diagnostic testing, drug concentration testing, and genetic testing	Adds laboratory or genetic information
Claims 11-14	Risk to the patient, fetus, bodily-fluid recipient, or sexual partner	Extends risk analysis beyond the treated patient
Claims 15-19	Periodic monitoring and compliance surveys	Adds recurring data collection, IVR, and pregnancy testing
Claims 20-27	Contraception, teratogenicity, thalidomide, pregnancy testing, 28-day supply	Narrow thalidomide and fetal-risk embodiments
Claims 28-32	Drug-drug interactions and testing for use of another drug	Separate interaction-risk method

How broad is independent claim 1?

Claim 1 is a system-of-method claim with several cumulative limitations. A potential infringement theory would need to show that the accused distribution program performs each required step or an equivalent step.

The most important limitations are:

A pre-existing controlled-distribution environment.
Registration of prescriber, pharmacy, and patient.
Multiple patient risk groups.
A predefined set of risk parameters.
Collection of information probative of adverse-event risk.
Assignment of the patient to a risk group.
A risk-acceptability determination.
Generation of a prescription approval code.
Pharmacy retrieval of that code before dispensing.

The claim does not expressly require the use of a particular database vendor, website, software platform, telephone system, pharmacy network, or coding format. It also does not require that the risk determination be performed by a particular algorithm or by artificial intelligence.

That breadth is limited by the claim's functional requirements. A conventional prescription database would not necessarily infringe. The database must perform risk stratification and generate a dispensing authorization after evaluating whether the relevant risk is acceptable.

What is the importance of the approval-code limitation?

The approval-code requirement is a significant narrowing feature. The pharmacy must retrieve a code before filling the prescription. A program that merely stores patient information or alerts a prescriber may fall outside the literal scope of claim 1 if it does not generate and use a pharmacy approval code.

The claim also requires the approval code to follow the determination that risk is acceptable. A code generated automatically for every registered patient, without a risk-acceptability determination, presents a weaker literal infringement case.

What do claims 2-20 add?

Claims 2-6 address counseling, disclosure, informed consent, verification, and fax-based data entry.

Claim 6 is particularly narrow. It requires transmission by facsimile and interpretation through optical character recognition software. A modern electronic signature, web form, or direct database entry would not literally satisfy that limitation, although it could remain relevant to an infringement analysis under the doctrine of equivalents.

Claims 7-10 cover diagnostic information. The patent identifies:

Testing for onset of the adverse effect.
Testing for drug concentration in patient tissue.
Genetic testing.

Claims 15-19 add periodic monitoring. Claim 17 covers telephone administration through an integrated voice response system. Claim 18 addresses pregnancy testing for a female of childbearing potential, and claim 19 sets the interval at about 28 days.

Claim 20 adds provision of a contraceptive device or formulation. This limitation is narrower than simply requiring counseling about contraception.

What do claims 21-27 protect for thalidomide?

Claims 21-27 are the most commercially significant claims for the thalidomide program.

Claim	Limitation
21	Adverse effect is teratogenicity
22	Drug is thalidomide
23	Teratogenic risk is to a fetus carried by the patient
24	Risk is to a fetus carried by a recipient of the patient's bodily fluid
25	Recipient is a sexual partner
26	Information includes pregnancy-test results
27	Prescription is filled for no more than approximately 28 days

Claim 22 depends from claim 1 and therefore retains all of claim 1's registration, risk-group, approval-code, and database limitations. It does not independently claim every controlled distribution program for thalidomide.

The strongest historical overlap with Celgene's commercial program would have involved a system that:

Registered prescribers, pharmacies, and patients.
Classified patients based on reproductive or fetal risk.
Required pregnancy testing.
Required informed consent and risk counseling.
Authorized dispensing through a code.
Limited the prescription supply to approximately 28 days.

The claims also extend to fetal exposure through a sexual partner's bodily fluid. That limitation reflects the patent's effort to cover reproductive-risk controls beyond direct use by a pregnant patient.

What do claims 28-32 cover?

Claims 28-32 establish a second independent claim framework for adverse effects caused by combining the drug with another drug.

The method must evaluate:

The risk caused by the combination.
The likelihood that the patient will use both drugs.
Evidence of use of the other drug.
Evidence indicating onset of the adverse effect.

Claim 28 repeats most of the claim 1 infrastructure, then adds the drug-combination limitation. Claims 29-32 narrow the information and testing requirements.

This group could have applied to drugs with serious interaction risks, such as anticoagulants, sedatives, immunosuppressants, or drugs with concentration-dependent toxicity. It is not limited to thalidomide.

When did U.S. Patent 6,315,720 expire?

U.S. Patent 6,315,720 expired in 2019, based on the 20-year patent term measured from the relevant nonprovisional filing date. The public patent record identifies a September 1999 nonprovisional filing and a September 15, 1998 priority claim. The effective patent term was approximately 20 years from the nonprovisional filing, subject to any applicable patent-term adjustment. The patent did not receive a commercially relevant extension that preserves enforceability today. (U.S. Patent and Trademark Office, n.d.-a)

Event	Date
Earliest identified priority	September 15, 1998
Nonprovisional filing	September 1999
Patent issued	November 13, 2001
Estimated statutory expiration	September 2019
Current status	Expired

Because the patent has expired, claims 1-32 do not create a current patent barrier to a generic manufacturer, pharmacy network, or software provider.

Historical damages analysis would require identifying accused conduct before expiration, proving each claim element, and addressing patent validity, prosecution history, claim construction, and applicable defenses.

What is the Orange Book status of Patent 6,315,720?

Patent 6,315,720 should not be treated as a current Orange Book patent barrier.

The patent claims a method for controlling access to a drug. It does not claim:

Thalidomide as an active ingredient.
A thalidomide capsule formulation.
A specific dosage strength.
A manufacturing process.
A composition of matter.
A conventional therapeutic method directed to treating a disease.

FDA Orange Book listings generally identify patents claiming the drug substance, drug product, or an approved method of use. A risk-management workflow patent may not qualify for listing merely because it relates to dispensing the drug. The FDA's approved thalidomide labeling and risk-management materials identify controlled-distribution requirements, but FDA approval of a risk-management program does not revive or extend an expired patent. (FDA, 2024a; FDA, 2024b)

Any historical Orange Book listing must be evaluated by the specific NDA patent record and historical listing date. Current generic entry does not depend on this patent because the patent term has ended.

What FDA regulatory program is associated with the patent?

Thalidomide is subject to a controlled distribution program because of its teratogenicity. The FDA-approved program has used prescriber and pharmacy registration, patient enrollment, pregnancy testing, counseling, contraception requirements, and limited dispensing.

The FDA's Risk Evaluation and Mitigation Strategies framework is a regulatory mechanism. It is separate from patent rights. A sponsor can operate an FDA-required or FDA-approved REMS after a related patent expires, and FDA can impose or modify safety controls without granting patent exclusivity. (FDA, 2024c)

The commercial relationship is direct but legally distinct:

Patent concept	FDA risk-management concept
Patient risk groups	Patient enrollment and risk classification
Information collection	Pregnancy tests, counseling, surveys, and attestations
Approval code	Dispensing authorization
Pharmacy registration	Certified pharmacy requirements
28-day supply	Limited prescription quantity
Patent exclusivity	Regulatory safety control

How strong were the claims from an infringement perspective?

The claims had meaningful historical value but presented several proof requirements.

Strengths

The patent used a detailed workflow rather than claiming only a general concept of monitoring patients. It identified specific actors and actions:

Prescriber registration.
Pharmacy registration.
Patient approval.
Risk-group assignment.
Risk evaluation.
Approval-code generation.
Pharmacy retrieval before dispensing.

Claims 22-27 also mapped closely to the operational controls used for thalidomide. That factual overlap could have supported infringement allegations against a substantially similar controlled-distribution system.

Weaknesses

The claims depend heavily on functional language, including:

"Probative of the risk."
"Determining whether the risk ... is acceptable."
"Approved to receive said drug."
"Qualified to prescribe."
"Qualified to fill."

Those terms could create claim-construction disputes. The patent also requires a particular sequence of events. An accused program that performs the same functions in a different order could contest literal infringement.

Claims 1 and 28 also require a "computer readable storage medium" containing or recording the relevant registration and approval information. A purely manual process would not satisfy the claim as written. Conversely, a modern electronic system could satisfy the medium limitation if it performs the claimed functions.

The patent's age created further vulnerability under later patent-eligibility doctrine. Claims directed to computerized data collection, risk classification, and authorization can raise issues under 35 U.S.C. § 101 if they are characterized as organizing human activity or implementing an abstract administrative process on generic computing equipment. Any historical validity analysis would depend on the patent's prosecution record, asserted claims, prior art, and the specific litigation posture. (U.S. Supreme Court, 2014)

Were there Paragraph IV challenges or generic litigation?

A Paragraph IV certification would have been relevant only while the patent was listed for an approved thalidomide product and remained unexpired. After September 2019, the patent could no longer support a forward-looking stay of FDA approval or a prospective injunction based solely on patent expiration.

Public information commonly associated with generic thalidomide competition concerns product patents, therapeutic-use patents, and regulatory certification issues rather than a continuing enforceable monopoly under Patent 6,315,720. Any historical Paragraph IV dispute must be separated from litigation involving other Celgene thalidomide patents.

The patent claim set alone does not establish:

That a particular generic manufacturer filed a Paragraph IV certification to this patent.
That Celgene asserted this patent in a particular ANDA case.
That a settlement licensed a generic entrant before expiration.
That a court entered an injunction involving this patent.

Those conclusions require the relevant complaint, ANDA notice, docket, or settlement document. The patent's present status is unaffected: it is expired.

Did the patent cover formulations or manufacturing methods?

No. Claims 1-32 do not claim a pharmaceutical formulation or manufacturing process.

They do not specify:

Capsule excipients.
Particle size.
Polymorphs.
Dissolution characteristics.
Extended-release technology.
Manufacturing steps.
Purification methods.
Packaging components as such.

Claim 20 mentions a contraceptive device or formulation, but only as an additional step in the patient-delivery method. It does not claim the contraceptive product itself.

A generic thalidomide applicant therefore would need to assess other patents covering the active ingredient, formulation, dosage form, method of treatment, labeling, or manufacturing process. Patent 6,315,720 is only a distribution-system patent within that broader landscape.

What is the biosimilar risk?

There is no biosimilar issue for thalidomide. Thalidomide is a small-molecule drug, not a biologic subject to the abbreviated biosimilar pathway under the Public Health Service Act.

The relevant competition is generic-drug competition under the Federal Food, Drug, and Cosmetic Act. A generic applicant would evaluate:

Abbreviated New Drug Application requirements.
Orange Book patents and certifications.
Labeling differences.
Controlled-substance or safety-program obligations.
Product and formulation patents.
Method-of-use patents.
Manufacturing and supply-chain rights.

Patent 6,315,720 does not create current biosimilar or generic entry risk because it expired in 2019.

How does Patent 6,315,720 compare with the FDA thalidomide program?

The patent and FDA program overlap operationally but have different legal functions.

Issue	Patent 6,315,720	FDA program
Primary purpose	Exclude competitors from practicing claimed method during patent term	Reduce fetal and other safety risks
Legal basis	Patent statute, 35 U.S.C. §§ 101-103, 271	FDA regulatory authority
Duration	Limited patent term	Continues while FDA requires or approves controls
Covered subject	Specific computerized risk-management workflow	Broader safety controls
Enforcement	Patent infringement action	Regulatory compliance and product authorization
Current effect	Expired	Safety controls may remain active

A company can therefore face continuing REMS-related operational requirements without facing infringement exposure under this patent.

What licensing and commercial barriers remain?

No current licensing obligation arises from an expired patent. A company distributing generic thalidomide may still need to address:

FDA approval and labeling.
Participation in any applicable controlled-distribution program.
Pharmacy and prescriber certification.
Patient enrollment and counseling.
Pregnancy testing and contraception controls.
Supply-chain and inventory controls.
Separate unexpired patents in the broader thalidomide portfolio.
Trademark and branding restrictions.

Patent 6,315,720 does not confer a continuing license right to Celgene or its successors. Any surviving commercial restriction would need to arise from another patent, contract, trademark, FDA condition, controlled-substance rule, or product-specific regulatory requirement.

What generic launch scenarios existed?

During the patent term, the principal launch scenarios were:

A generic applicant waited for expiration and launched without challenging the patent.
An applicant filed a Paragraph IV certification and litigated validity or infringement.
The applicant entered under a settlement or license.
The applicant launched with a restricted label or after removing a patented method of use.
The applicant challenged whether the distribution workflow was properly listed or infringed.

After expiration, the patent could no longer prevent launch. A current launch analysis should focus on other listed patents, FDA requirements, product supply, and operational compliance rather than Patent 6,315,720.

Key Takeaways

Patent 6,315,720 covers a computerized controlled-distribution method for drugs with serious adverse-event risks.
Claim 1 requires risk groups, patient information, risk assessment, database registration, and a pharmacy approval code.
Claims 22-27 specifically address thalidomide, teratogenicity, pregnancy testing, fetal exposure, and 28-day prescriptions.
Claims 28-32 address adverse effects caused by combining a drug with another drug.
The patent does not claim thalidomide, a thalidomide formulation, or a manufacturing process.
The patent expired in approximately September 2019.
It is not a current barrier to generic thalidomide entry.
There is no biosimilar pathway issue because thalidomide is a small-molecule drug.
FDA risk-management requirements can continue after patent expiration.
Current commercial risk must be assessed against other thalidomide patents, FDA obligations, product labeling, and controlled-distribution requirements.

FAQs

Does Patent 6,315,720 still protect the S.T.E.P.S. program?

No. The patent's claims may have historically covered aspects of a thalidomide controlled-distribution workflow, but the patent expired in 2019. FDA regulatory requirements can continue independently.

Can a generic company use a different thalidomide approval-code system?

Yes, provided the alternative system satisfies FDA requirements and does not infringe another unexpired patent. Patent 6,315,720 itself no longer creates prospective infringement liability after expiration.

Does claim 22 cover every prescription of thalidomide?

No. Claim 22 depends on claim 1 and requires the full claimed database, registration, risk-group, risk-assessment, and pharmacy approval-code workflow.

Does the patent claim pregnancy testing by itself?

No. Pregnancy testing appears in dependent claims, including claims 18 and 26. Those claims require the broader method limitations from the claims on which they depend.

Can the patent be extended because thalidomide remains subject to FDA controls?

No. FDA safety controls do not extend an expired patent. Patent-term extension requires statutory eligibility and a qualifying regulatory review period, and a REMS or controlled-distribution requirement does not independently revive patent rights.

References

Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024b). Thalomid (thalidomide) prescribing information. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024c). Risk evaluation and mitigation strategies. U.S. Department of Health and Human Services.
U.S. Patent and Trademark Office. (n.d.-a). U.S. Patent No. 6,315,720, Method for delivering a drug to a patient while avoiding adverse side effects. U.S. Department of Commerce.
U.S. Patent and Trademark Office. (n.d.-b). Manual of Patent Examining Procedure: Patent term and patent-term adjustment. U.S. Department of Commerce.
U.S. Supreme Court. (2014). Alice Corp. v. CLS Bank International, 573 U.S. 208.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	1437201	⤷ Start Trial
Australia	2005201675	⤷ Start Trial
Australia	780486	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,315,720

Summary for Patent: 6,315,720