Exelixis v. MSN Laboratories — Federal Circuit Cross-Appeal Dismissed (Case 25-1241)
Exelixis, Inc. filed a cross-appeal at the Federal Circuit asserting three patents covering its CABOMETYX cabozantinib franchise against generic challenger MSN Laboratories. The appeal was dismissed by agreement under Fed. R. App. P. 42(b) after 189 days, with each side bearing its own costs — leaving the underlying patent landscape unresolved on the merits.
Exelixis cabozantinib cross-appeal ends without a Federal Circuit merits ruling
Exelixis, Inc., the oncology company behind the CABOMETYX (cabozantinib) franchise, filed cross-appeal No. 25-1241 at the U.S. Court of Appeals for the Federal Circuit on 3 December 2024. The appeal concerned three U.S. patents — US11091440B2, US11098015B2, and US11091439B2 — directed to cabozantinib, a tyrosine kinase inhibitor approved for renal cell carcinoma and other cancers. The defendant and opposing party was MSN Laboratories Private, Ltd., an Indian generic pharmaceutical manufacturer, in the context of an infringement action consistent with ANDA-related litigation.
The Federal Circuit dismissed the cross-appeal on 10 June 2025 pursuant to Fed. R. App. P. 42(b), which permits voluntary dismissal of an appeal by agreement of the parties. The court ordered that each side bear its own costs. Because the dismissal was stipulated and procedural, no appellate merits decision was rendered — meaning the Federal Circuit issued no ruling on claim construction, validity, or infringement with respect to the three asserted cabozantinib patents.
The 189-day lifespan of this cross-appeal is notably brief for Federal Circuit proceedings, suggesting the parties reached a resolution — or a strategic agreement to end this appellate track — relatively quickly after filing. The absence of a merits ruling means the enforceability and validity of the three patents remain formally unresolved in this proceeding. What drove the agreement, including any underlying settlement or license terms in the broader district court litigation, is not reflected in the public appellate record.
Filing to Appeal Dismissed in 189 days
189 days — resolved in under 6 months at the Federal Circuit, faster than most merits appeals
Appeal dismissed by agreement: what the procedural end means for both parties
Fed. R. App. P. 42(b) dismissal — no merits adjudication
Rule 42(b) allows parties to voluntarily dismiss a federal appeal by stipulation. The Federal Circuit’s order here reflects mutual agreement to end the cross-appeal without the court ruling on validity, infringement, or claim construction. This is a procedural close — not a substantive win or loss on the patent questions raised. It leaves the three cabozantinib patents in the same formal legal posture they held before the appeal was filed.
Voluntary appellate dismissalExelixis exits appeal without a Federal Circuit endorsement or rebuke
As cross-appellant, Exelixis was seeking appellate review of an adverse or incomplete district court outcome. The voluntary dismissal means Exelixis does not obtain a Federal Circuit ruling in its favour, but also avoids a potential adverse precedent on the asserted patents. The three cabozantinib patents remain enforceable unless and until challenged in another proceeding. The public record does not disclose whether any licensing arrangement underpins the dismissal.
No merits ruling for patent holderMSN avoids appellate loss — but patent threat persists
MSN Laboratories benefits from the dismissal insofar as no Federal Circuit precedent now affirms Exelixis’s patents against it. However, the underlying patents — US11091440B2, US11098015B2, and US11091439B2 — remain in force and could be asserted again in fresh proceedings. Generic market entry for cabozantinib remains contingent on the broader patent landscape, including any district court outcomes or IPR proceedings not resolved by this dismissal.
No clear path to generic entryCabozantinib generic competition timeline remains uncertain
CABOMETYX generated substantial annual revenues for Exelixis. The unresolved status of three key cabozantinib patents following this appeal dismissal means generic manufacturers — including MSN — face continued uncertainty about market entry timing. Competitors and investors monitoring the cabozantinib generic landscape should note that this Federal Circuit dismissal resolves no substantive question, and parallel proceedings or future ANDA litigation remain the operative risk vectors.
Generic entry timeline unresolvedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Exelixis, Inc. | Company | Oncology innovator and holder of US11091440B2, US11098015B2, and US11091439B2 covering cabozantinibSearch in Eureka ↗ |
| Defendant | MSN Laboratories Private, Ltd. | Company | MSN Laboratories Private, Ltd. — Indian generic pharmaceutical manufacturer and ANDA applicantSearch in Eureka ↗ |
| Plaintiff counsel | Anthony D. Raucci | Attorney | Counsel for Exelixis, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Morris, Nichols, Arsht & Tunnell LLP | Law Firm | Representing Exelixis, Inc.Search in Eureka ↗ |
| Defendant counsel | Bryce Cooper | Attorney | Counsel for MSN Laboratories Private, Ltd.Search in Eureka ↗ |
| Defendant counsel | Kurt A. Mathas | Attorney | Counsel for MSN Laboratories Private, Ltd.Search in Eureka ↗ |
| Defendant law firm | Winston & Strawn, LLP | Law Firm | Representing MSN Laboratories Private, Ltd.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The Federal Circuit’s order is narrow and purely procedural: the cross-appeal is dismissed by mutual stipulation under Fed. R. App. P. 42(b), with a symmetrical costs ruling. The court issues no opinion on the merits — no claim construction, no validity assessment, and no infringement determination with respect to the three cabozantinib patents. For practitioners, the significance lies in what the order does not say: the appellate record is silent on the strength of Exelixis’s patent positions, meaning neither party can cite this order as precedent in future proceedings.
US11091440B2, US11098015B2 & US11091439B2 — cabozantinib compound and formulation patents
The three patents at issue — US11091440B2, US11098015B2, and US11091439B2 — are U.S. utility patents held by Exelixis covering aspects of cabozantinib, a multi-targeted tyrosine kinase inhibitor that blocks MET, VEGFR, and other receptor kinases implicated in tumour progression. Cabozantinib is the active pharmaceutical ingredient in CABOMETYX, approved by the FDA for renal cell carcinoma, hepatocellular carcinoma, and differentiated thyroid cancer. The patents originate from application numbers US17/149365, US17/171752, and US17/070514 respectively, suggesting a filing cluster consistent with continuation or divisional prosecution strategy to broaden patent protection around the cabozantinib molecule.
For the pharmaceutical sector, a portfolio of three closely related patents covering the same active ingredient represents a layered exclusivity strategy — each patent potentially covering distinct claims around the compound, its salt forms, formulations, or methods of use. This layering complicates generic ANDA filings because challengers must address each patent independently. With none of the three patents adjudicated on the merits in this proceeding, competitors face an unresolved enforcement risk. The fact that MSN Laboratories, a generic manufacturer, was the opposing party is consistent with Paragraph IV ANDA certification litigation, a high-stakes context in which patent holders and generic entrants routinely litigate at the Federal Circuit.
Should you run an FTO analysis against US11091440B2, US11098015B2, and US11091439B2?
Any company developing, manufacturing, or seeking to commercialise a generic or biosimilar cabozantinib product — or any tyrosine kinase inhibitor with overlapping structural or formulation claims — should treat these three Exelixis patents as active FTO risks. The Federal Circuit’s dismissal of Case 25-1241 without a merits ruling means there is no judicial determination of invalidity or non-infringement to rely on. R&D teams working in the oncology small-molecule space, particularly MET/VEGFR inhibitors, should also assess whether their compound or formulation work falls within the claim scope of the ‘440, ‘015, or ‘439 patents.
PatSnap Eureka’s FTO Search Agent can map the claim landscapes of US11091440B2, US11098015B2, and US11091439B2 against your compound or formulation pipeline, identify prior art relevant to potential IPR filings, and surface related continuation and divisional applications in the Exelixis portfolio that may extend protection beyond these three patents. Given the absence of any Federal Circuit claim construction in this case, Eureka’s claim analysis tools provide a critical independent read on the scope and enforceability risk your team faces.
Run a freedom-to-operate analysis on US11091440B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit ANDA patent appeals in the oncology small-molecule sector
Explore comparable Federal Circuit appeals involving oncology kinase inhibitor patents and ANDA-related infringement actions dismissed or resolved without merits rulings.
What this case signals for the oncology generics IP landscape
A stipulated Federal Circuit dismissal in ANDA-adjacent litigation often signals more than it reveals — here is what IP teams should track.
Stipulated dismissals at the Federal Circuit typically signal a negotiated resolution
When parties jointly dismiss a Federal Circuit appeal under Rule 42(b), it commonly reflects a settlement, license, or agreed entry date in the underlying pharmaceutical dispute. IP counsel monitoring cabozantinib generic competition should treat this dismissal as a potential indicator of a private arrangement rather than a clean patent victory for either side.
Three cabozantinib patents remain formally in force after this dismissal
US11091440B2, US11098015B2, and US11091439B2 were not invalidated or held unenforceable in this proceeding. Any generic manufacturer considering ANDA filings for cabozantinib products must independently assess the enforceability and claim scope of these patents, as no appellate court has adjudicated their validity.
Exelixis v MSN — key questions answered
The Federal Circuit dismissed Exelixis’s cross-appeal by stipulation under Rule 42(b), which allows parties to voluntarily end an appeal without a merits ruling. No determination was made on the validity or infringement of the three cabozantinib patents. The three patents — US11091440B2, US11098015B2, and US11091439B2 — remain formally in force.
Exelixis asserted three U.S. patents: US11091440B2 (application US17/149365), US11098015B2 (application US17/171752), and US11091439B2 (application US17/070514). All three relate to cabozantinib, the active ingredient in CABOMETYX, and were the subject of an infringement action against MSN Laboratories as a generic pharmaceutical manufacturer.
CABOMETYX is Exelixis’s branded cabozantinib product, a tyrosine kinase inhibitor approved for renal cell carcinoma, hepatocellular carcinoma, and differentiated thyroid cancer. MSN Laboratories, as a generic manufacturer, is consistent with having filed an ANDA seeking approval for a generic cabozantinib product, triggering Paragraph IV patent infringement litigation that ultimately reached the Federal Circuit.
Neither party won or lost on the merits. The Federal Circuit dismissed the cross-appeal by mutual agreement under Rule 42(b) with each side bearing its own costs. This procedural resolution means no appellate judgment was entered on the patent claims, and the public record does not disclose any underlying settlement or licensing terms.
Because the Federal Circuit issued no merits ruling, there is no judicial determination of invalidity or non-infringement that generic manufacturers can rely on. US11091440B2, US11098015B2, and US11091439B2 remain enforceable patents. Companies pursuing generic cabozantinib products must independently assess FTO against these patents, including potential IPR challenges, before commercialisation.
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