Anacor v. Alkem: EUCRISA® Crisaborole Patent Dispute Settled After 699 Days
Anacor Pharmaceuticals and PF Prism IBM C.V. sued Alkem Laboratories in the Delaware District Court over four patents protecting crisaborole ointment 2% (EUCRISA®). The parties reached a settlement and licence agreement after 699 days, with all claims and counterclaims dismissed without prejudice and the court retaining jurisdiction to enforce the agreement.
Four crisaborole patents, one ANDA challenger, and a negotiated exit
On 24 September 2021, Anacor Pharmaceuticals, Inc. and co-plaintiff PF Prism IBM C.V. filed suit against Alkem Laboratories Ltd. in the District of Delaware (Civil Action No. 1:21-cv-01348, consolidated with No. 21-1350). The complaint charged Alkem with infringement of four US patents — US8039451B2, US8168614B2, US8501712B2, and US9682092B2 — each directed to crisaborole ointment 2%, marketed by the plaintiffs as EUCRISA®, a PDE4 inhibitor approved for atopic dermatitis.
The recorded basis of termination is 'Case Settled.' The docket order, entered as a stipulated dismissal, states that all claims and counterclaims between the parties are dismissed without prejudice, that each party bears its own costs and attorneys' fees, and that the parties have entered into a settlement and licence agreement. The order further records that Alkem will not make, have made, use, offer for sale, or sell the accused crisaborole ointment 2% product in the United States except as permitted under that agreement. The court retained jurisdiction to enforce both the stipulation and the settlement and licence agreement.
Resolution after approximately 23 months — before any claim construction or merits ruling — is consistent with a negotiated outcome driven by the commercial value of the EUCRISA® franchise and the complexity of defending four patents simultaneously. The specific financial or royalty terms of the settlement and licence agreement are not disclosed in the available public record.
See Complete Case & Patent Analysis →Filing to Case Settled in 699 days
699 days — nearly two years from filing to settlement in Delaware
US8039451, US8168614, US8501712 & US9682092 — crisaborole ointment 2%
Any company developing a topical crisaborole formulation, a structurally related boron-containing PDE4 inhibitor, or a generic equivalent of EUCRISA® for the US market should conduct a freedom-to-operate analysis against all four patents. The product-restraint clause in the Alkem settlement confirms these patents are actively enforced. R&D teams working on atopic dermatitis therapeutics in the PDE4 inhibitor class should also assess method-of-use claims, which can capture clinical use even where formulation claims are designed around.
Official order — verbatim text
The stipulated order records dismissal of all claims and counterclaims without prejudice, with each party bearing its own costs. Notably, the order simultaneously records a settlement and licence agreement and a product-restraint obligation on Alkem — elements that go beyond a bare dismissal and suggest a substantive negotiated resolution. The specific financial or licensing terms of that agreement are not disclosed in the available public record.
Case settled: what the agreed resolution means for both parties
Settlement and licence agreement ends four-patent dispute
The case closed through a stipulated order of dismissal without prejudice, underpinned by a separately executed settlement and licence agreement between the parties. The court retained jurisdiction to enforce both documents. This structure means the litigation risk is extinguished, but the agreement itself remains a binding instrument — any breach could return the parties to this court.
Court-retained jurisdictionAnacor secures licence terms and product restraint on Alkem
Under the recorded order, Alkem is prohibited from making, using, offering for sale, or selling the accused crisaborole ointment 2% product in the United States except as the settlement and licence agreement expressly permits. For Anacor and PF Prism, this suggests continued control over the EUCRISA® commercial window. The financial or royalty terms of the licence are not disclosed in the available public record.
Product restraint recordedAlkem's US market access governed by licence agreement
Alkem's ability to commercialise its crisaborole ointment 2% in the United States is now governed by the settlement and licence agreement rather than by unrestrained generic competition. All counterclaims Alkem had asserted are also dismissed without prejudice. The specific scope of any licence grant — including timing of any permitted market entry — is not disclosed in the available public record.
Counterclaims dismissedEUCRISA® patent estate reinforced against this ANDA challenger
Settlement with a licence and product-restraint clause, before any merits ruling, suggests the four asserted patents presented a credible enforcement barrier. Other potential ANDA filers for crisaborole ointment 2% should note that US8039451, US8168614, US8501712, and US9682092 remain active enforcement tools. Companies developing PDE4 inhibitor topical formulations in this class should assess FTO exposure across this portfolio.
Portfolio enforcement signalFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Anacor Pharmaceuticals, Inc. | Company | /Search in Eureka ↗ |
| Co-Plaintiff | PF Prism Ibm C.V. | Individual | Search in Eureka ↗ |
| Defendant | Alkem Laboratories, Ltd. | Company | /Search in Eureka ↗ |
| Plaintiff counsel | Amit H. Thakore | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | C. Sebastian Zonte | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Dimitrios T. Drivas | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Elizabeth Chang | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Jack B. Blumenfeld | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | John P. Scheibeler | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Megan Elizabeth Dellinger | Attorney | Counsel for Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Morris, Nichols, Arsht & Tunnell LLP | Law Firm | Representing Anacor Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Kate Harmon | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant counsel | Kevin M. Capuzzi | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant counsel | Louis Constantinou | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant counsel | Manish K. Mehta | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant counsel | Michael S. Weinstein | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant counsel | Samuel J. Ruggio | Attorney | Counsel for Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Defendant law firm | Benesch, Friedlanders, Coplan & Aronoff LLP | Law Firm | Representing Alkem Laboratories, Ltd.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Delaware District CourtSearch in Eureka ↗ |
R&D signals in the crisaborole & topical PDE4 inhibitor space
Forward-looking patent and R&D intelligence derived from Anacor's four-patent crisaborole estate and Alkem's competitive position in topical dermatology.
Anacor's crisaborole patent family depth beyond this case
The four asserted patents represent a slice of Anacor's broader crisaborole prosecution activity. Mapping the full family — including continuation applications, international equivalents, and any post-grant proceedings — reveals the remaining exclusivity runway and the defensive perimeter Pfizer (Anacor's parent) has built around EUCRISA®. Portfolio depth here directly affects the commercial window for any authorised or generic entrant.
Portfolio depth signalFiling trends in topical PDE4 inhibitors for atopic dermatitis
Since crisaborole's FDA approval, filing activity in topical PDE4 inhibitors and JAK inhibitor alternatives for atopic dermatitis has intensified. Tracking recent patent applications in boron-containing anti-inflammatories and next-generation topical immunomodulators reveals where the field is heading and which players are building around the Anacor estate — intelligence critical for R&D investment decisions in this therapeutic area.
Emerging competitor filingsAlkem's patent activity in topical dermatology formulations
As a major generic manufacturer, Alkem's own patent filings in topical formulation technology can signal where it is building proprietary differentiation beyond ANDA strategies. Analysing Alkem's portfolio in dermatological drug delivery — including ointment base technologies and transdermal penetration enhancers — indicates whether it is positioning for branded or formulation-IP-based competition in the atopic dermatitis space.
Generic-to-branded IP shiftAdjacent opportunities around crisaborole's mechanism of action
PDE4 inhibition as a topical mechanism remains under-explored outside atopic dermatitis — psoriasis, seborrheic dermatitis, and contact dermatitis are adjacent indications with limited filed art. R&D teams can use the claim boundaries of the four asserted patents as a whitespace map: formulations, delivery vehicles, or indication-specific claims not covered by US8039451–US9682092 represent potential filing opportunities in a space validated by EUCRISA®'s commercial success.
Adjacent indication white spaceSimilar ANDA patent cases involving topical dermatology formulations
Explore comparable Paragraph IV infringement actions in the Delaware District Court involving topical pharmaceutical formulations and PDE4 inhibitor patents.
What this case signals for the topical dermatology IP landscape
A four-patent settlement with court-retained jurisdiction sends a clear enforcement signal to other crisaborole ANDA filers and PDE4 inhibitor developers.
Four-patent assertion strategy raises the cost of ANDA challenges
Asserting four patents simultaneously across formulation and method-of-use claims increases litigation cost and settlement leverage for originators. Generic filers challenging EUCRISA® face a multi-front invalidity burden. Companies contemplating ANDA filings for crisaborole or structurally similar PDE4 inhibitors should model this litigation cost premium into their go/no-go analysis.
Court-retained jurisdiction extends post-settlement risk for Alkem
The court's retained jurisdiction to enforce both the stipulation and the licence agreement means this matter is not fully closed for Alkem. Any commercialisation outside the licence terms could re-activate Delaware proceedings without a new filing. In-house teams at generic manufacturers should build licence-compliance monitoring into their product launch protocols for the crisaborole segment.
Anacor v Alkem — key questions answered
Anacor Pharmaceuticals and PF Prism IBM C.V. asserted four patents: US8039451B2, US8168614B2, US8501712B2, and US9682092B2. All four cover aspects of crisaborole ointment 2%, marketed as EUCRISA®, a topical PDE4 inhibitor for atopic dermatitis.
The recorded basis of termination is 'Case Settled.' The docket order records a stipulated dismissal of all claims and counterclaims without prejudice, coupled with a settlement and licence agreement. The court retained jurisdiction to enforce both the stipulation and the licence agreement. The specific financial or royalty terms are not disclosed in the available public record.
The recorded order states that Alkem will not make, have made, use, offer for sale, or sell its accused crisaborole ointment 2% product in the United States except as permitted under the settlement and licence agreement. The scope of any licence grant — including any permitted entry date — is not disclosed in the available public record.
The public record does not disclose the parties' reasons for settlement. Resolution after approximately 23 months and before any merits ruling is consistent with, though not confirmed to reflect, commercial considerations around the EUCRISA® franchise, the multi-patent assertion burden, and the costs of continued litigation. No judicial guidance on claim scope was produced in this matter.
The dismissal is without prejudice and no invalidity or unenforceability ruling was issued. The patents are not extinguished by this resolution and remain active enforcement tools against other parties. The product-restraint clause in the Alkem order confirms Anacor continued to assert these patents as valid and infringed at the time of settlement.
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