Japanese company Eisai announced on May 29, 2025 that it has received a favorable judgment in United States District Court in New Jersey against India-based manufacturer Shilpa Medicare (1). According to a press release announcing the court’s decision, Shilpa had submitted an Abbreviated New Drug Application (ANDA) to FDA for a generic version of lenvatinib mesylate, which Eisai markets as Lenvima under US Patent No. 11,186,547 (the ‘547 Patent). Eisai said that the ‘547 Patent is directed to highly pure lenvatinib mesylate as found in Lenvima, an orally available multiple receptor tyrosine kinase inhibitor, and that the decision of the court upheld the validity of the patent.
As a result, Shilpa will not be able to receive FDA approval for its lenvatinib mesylate generic until the ‘547 Patent, and related exclusivity, expires in February 2036 (1).
A decade on the market
Key Takeaways
- Eisai successfully defended its Lenvima patent, preventing Shilpa Medicare from launching a generic until at least February 2036 due to a US District Court ruling.
- This marks Eisai's fourth ANDA-related legal proceeding in the last two years, reinforcing its IP strategy as key generic challengers face delays or confidential settlements.
- Despite legal wins, Eisai faces clinical and regulatory setbacks, including competition in liver cancer treatment and rejection of lecanemab in Australia.
Eisai’s lenvatinib offering was first approved by FDA in February 2015 for the treatment of progressive, differentiated thyroid cancer in patients whose disease had progressed after receiving radioactive iodine therapy (2). In March 2018, Merck, known as MSD outside the United States and Canada, entered into a strategic collaboration with Eisai to jointly develop and commercialize Lenvima globally, both as a monotherapy and in combination with Merck’s anti-cancer biologic, Keytruda (pembrolizumab), for treating multiple cancer types, a deal that was reported at the time to have the potential to reach up to $5.76 billion (3).
The judgment won by Eisai against Shilpa represents the fourth patent infringement lawsuit Eisai has filed since 2024 over ANDA submissions. A prior lawsuit against Sun Pharmaceutical Industries was settled under the terms of which Sun Pharma cannot launch its generic lenvatinib product in the US until July 1, 2030, unless defined contingencies occur before that date; certain terms of that settlement agreement have been kept confidential (1). Dr. Reddy’s Laboratories and Torrent were two other companies against which Eisai commenced patent infringement lawsuits in 2024.
Roadbumps for Eisai
As a tyrosine kinase inhibitor monotherapy, lenvatinib performed unfavorably to the combination of nivolumab plus ipilimumab (brand names Opdivo and Yervoy, respectively) in a global Phase III trial, the results of which led to FDA approving the pairing of those two Bristol Myers Squibb drugs in April 2025 for first-line treatment for unresectable or metastatic hepatocellular carcinoma (4).
Additionally, Eisai experienced a setback in March 2025 when its lecanemab, a humanized anti-soluble aggregated amyloid-beta monoclonal antibody intended for the treatment for early Alzheimer’s disease, had its approval declined by the Therapeutic Goods Administration of Australia, which cited risk factors for amyloid-related imaging abnormalities (5).
In reference to the US District Court’s decision regarding Shilpa, Eisai said the judgment should not have an impact on consolidated financial forecasts for the fiscal year ending March 31, 2026 (1). Sales revenue for Lenvima in the US for the fiscal year ending March 31, 2025 totaled 229.6 billion yen (US$1.6 billion).
References
1. Eisai. Eisai Obtains Favorable Decision in Patent Infringement Litigation Related to Lenvatinib in the US. Press Release. May 29, 2025.
2. Eisai. FDA Approves Eisai’s Lenvima (lenvatinib) for the Treatment of Patients with Locally Recurrent or Metastatic, Progressive, Radioactive Iodine-Refractory Differentiated Thyroid Cancer. Press Release. Feb. 13, 2015.
3. Merck. Eisai Co., Ltd. and Merck Enter Global Strategic Oncology Collaboration for Lenvima (lenvatinib mesylate). Press Release. March 7, 2018.
4. BMS. US Food and Drug Administration Approves Opdivo (nivolumab) plus Yervoy (ipilimumab) as a First-Line Treatment for Unresectable or Metastatic Hepatocellular Carcinoma. Press Release. April 11, 2025.
5. Eisai. Eisai Receives Regulatory Review Outcome for Lecanemab as a Treatment for Early Alzheimer’s Disease in Australia. Press Release. March 3, 2025.
