Partner
Mark Feldstein, Ph.D., focuses on U.S. district court litigation, primarily concerning the enforcement of U.S. patent rights and trade secret issues, and post-grant trial proceedings at the U.S. Patent and Trademark Office (USPTO), including inter partes review (IPR) and post grant review (PGR). He has particular experience with litigations arising from Abbreviated New Drug Applications (ANDAs) under the Hatch-Waxman Act.
Mark also maintains an active patent prosecution practice, preparing and prosecuting U.S. patent applications on behalf of domestic and foreign clients. In addition, he provides opinions and strategic guidance to clients on infringement, validity, enforceability, and clearance matters. In Acritas Stars, clients have praised his extensive knowledge of patent law; depth of technical and legal expertise, and the quality of advice; and determination to get things done. LMG Life Sciences has nominated Mark as the Post-Grant Proceedings Attorney of the Year and has also noted his contributions to the fields of "General Patent Litigation" and "Hatch-Waxman Patent Litigation."
Mark's practice encompasses a range of technologies, including pharmaceuticals, chemicals, biochemistry, polymers, small molecule chemistry, nanotechnology, optics, and medical and analytic devices. His proficiency in these areas is supported by extensive research experience. Prior to his legal career, Mark conducted research in ultrafast laser spectroscopy and scanning probe microscopy analysis applied to metallic, nano-structured, and conducting polymeric systems. As a National Research Council post-doctoral associate, Mark also designed and developed optically transduced biosensors and related signal processing software for the U.S. Naval Research Laboratory.
Mark is an adjunct professor of law at Georgetown University Law Center, teaching courses in patent prosecution practice and IP management. He regularly speaks to national and international audiences of both attorneys and scientists on issues of patent strategy, prosecution, and litigation. Mark is also an associate editor for texts published by the American Bar Association Section of Intellectual Property Law on ANDA litigation law and strategy, and by AIPLA/Bloomberg BNA on evidence in patent litigations.
Mark's pro bono activities include military veteran representation before the U.S. Court of Appeals for Veterans Claims.
Lead counsel representing Merck in Hatch-Waxman litigations involving the HIV drugs ISENTRESS®and ISENTRESS®HD.
2:23-cv-00094, 2:23-cv-02364, D.N.J., Judges Cecchi, Padin, Wettre
Lead counsel for Incyte in Federal Circuit appeal of IPR against a patent claiming deuterated versions of the active ingredient in Incyte’s FDA approved Jakafi® product (ruxolitinib); secured a unanimous affirmance of the PTAB’s obviousness determination.
19-2011, Fed. Cir., Judges Hughes, Linn, Stark
IPR2017-01256, PTAB, Judges Franklin, Hulse, Smith
Successfully represented Eli Lilly in defensive patent litigation and served as lead counsel in offensive inter partes reviews (IPRs) regarding products related to the treatment of migraines.
IPR2022-00738, -00739, -00796, PTAB, Judges Cotta, Wisz, Worth
1:21-cv-10954, D. Mass., Judge Burroughs
Successfully represented Alzheon, Inc. in inter partes reviews (IPRs) defending patents related to tramiprosate, a treatment for Alzheimer’s Disease. Continuing representation at the Federal Circuit.
IPR2022-01200, PGR2022-00051, PTAB, Judges Newman, Snedden, Wisz
22-2232, Fed. Cir.
Representing Eli Lilly as lead counsel in Hatch-Waxman action against several defendants relating to Cialis®.
1:16-cv-01119, E.D. Va., Judges Nachmanoff, Trenga
Successfully represented petitioner Equistar as lead counsel in an inter partes review (IPR), resulting in a ruling of unpatentability for all claims of a patent directed to an apparatus and process of manufacturing polyethylene in a high-pressure tubular reactor.
IPR2017-01534, PTAB, Judges Abraham, Roesel, Tornquist
Successfully defended Incyte Corp. against a PGR petition related to deuterated versions of the active ingredient in Incyte’s FDA approved Jakafi® product (ruxolitinib), achieving a non-institution decision from the PTAB.
PGR2017-00034, PTAB, Judges Paulraj, Sawert, Snedden
IPR2014-00693, -00752, PTAB, Judges Green, Prats, Snedden
16-1547, Fed. Cir., Judges Bryson, Moore, Newman
16-1155, -1259, Fed. Cir., Judges Moore, Reyna, Taranto
1:12-cv-03846, N.D. Ill., Judge Pallmeyer
IPR2015-00561, -00562, PTAB, Judges Mitchell, Snedden, Yang
IPR2016-00235, -00564, PTAB, Judges Chagnon, McKelvey, Medley, Snedden
1:15-cv-01000, D. Del., Judge Andrews
1:05-cv-00737, D. Del., Judges Farnan, Stark
14-1431, -1462, Fed. Cir., Judges Dyk, Prost, Wallach
5:11-cv-00017, W.D.N.C., Judges Keesler, Voorhees
1:10-md-02200, D. Del., Judge Sleet
1:06-cv-01017, S.D. Ind., Judges Barker, Magnus-Stinson
09-1071; 10-1005, -1033, Fed. Cir., Judges Linn, Michel, Prost, Rader
1:04-cv-00305, D. Del., Judge Robinson
06-1472, Fed. Cir., Judges Gajarsa, O'Malley, Rader
1:04-cv-01278, D. Del., Judge Jordan
Incyte Corporation et al. v. Sun Pharmaceutical Industries Limited et al.
Lead counsel for Incyte in patent litigation related to Sun Pharmaceuticals’ deuterated Janus kinase (JAK) inhibitor, LEQSELVI™.
2:24-cv-06944, D.N.J., Judge Padin
Merck Sharp & Dohme LLC v. Hetero USA Inc., Lupin Limited et al.
Lead counsel representing Merck in Hatch-Waxman litigations involving the HIV drugs ISENTRESS®and ISENTRESS®HD.
2:23-cv-00094, 2:23-cv-02364, D.N.J., Judges Cecchi, Padin, Wettre
Incyte Corp. v. Concert Pharmaceuticals, Inc.
Lead counsel for Incyte in Federal Circuit appeal of IPR against a patent claiming deuterated versions of the active ingredient in Incyte’s FDA approved Jakafi® product (ruxolitinib); secured a unanimous affirmance of the PTAB’s obviousness determination.
IPR2017-01256, PTAB, Judges Fitzpatrick, Hulse, Yang, Smith, Franklin
19-2011, Fed. Cir., Judges Hughs, Linn, Stark
Teva Pharmaceuticals International GmbH v. Eli Lilly and Company
Successfully represented Eli Lilly in defensive patent litigation and served as lead counsel in offensive inter partes reviews (IPRs) regarding products related to the treatment of migraines.
IPR2022-00738, -00739, -00796, PTAB, Judges Cotta, Wisz, Worth
1:21-cv-10954, D. Mass., Judge Burroughs
Risen (Suzhou) Pharma Tech Co., Ltd. v. Alzheon, Inc.
Successfully represented Alzheon, Inc. in inter partes reviews (IPRs) defending patents related to tramiprosate, a treatment for Alzheimer’s Disease. Continuing representation at the Federal Circuit.
IPR2022-01200, PGR2022-00051, PTAB, Judges Newman, Snedden, Wisz
22-2232, Fed. Cir.
Eli Lilly and Company v. Actavis Labs. UT Inc.
Representing Eli Lilly as lead counsel in Hatch-Waxman action against several defendants relating to Cialis®.
1:16-cv-01119, E.D. Va., Judges Nachmanoff, Trenga
Webinar
Litigating Chemical Cases at the ITC: Procedural Considerations and Claiming Strategies Litigating Chemical Cases at the ITC: Procedural Considerations and Claiming Strategies
January 29, 2025
Webinar
At the PTAB Blog
Trends in PTAB Trials Involving Drug and Biologic Patents Trends in PTAB Trials Involving Drug and Biologic Patents
June 26, 2024
Books
Biosimilars Litigation and Client Counseling Biosimilars Litigation and Client Counseling
June 17, 2024
American Bar AssociationWebinar
Biologics and Biosimilars: FDA Initiatives and Guidance, Approvals and Exclusivity, Patent Prosecution, Litigation Biologics and Biosimilars: FDA Initiatives and Guidance, Approvals and Exclusivity, Patent Prosecution, Litigation
February 15, 2024
Webinar
“He’s brilliant. He’s a patent litigator, he has excellent technical skills, and he’s an excellent attorney…”
Acritas Stars™
“He’s brilliant. He’s a patent litigator, he has excellent technical skills, and he’s an excellent attorney…”
Acritas Stars™
Press Release
Finnegan Recognized as a Leading Firm in the 2025 LMG Life Sciences Americas Rankings Finnegan Recognized as a Leading Firm in the 2025 LMG Life Sciences Americas Rankings
October 1, 2025
LMG Life SciencesMedia Mention
NJ Judge Blocks Sun Pharma from Launching Hair Loss Drug NJ Judge Blocks Sun Pharma from Launching Hair Loss Drug
November 4, 2024
Law360Award/Ranking
Finnegan Remains a Tier 1 Firm in the 2024 LMG Life Sciences Rankings Finnegan Remains a Tier 1 Firm in the 2024 LMG Life Sciences Rankings
October 4, 2024
LMG Life SciencesAward/Ranking
Finnegan Shortlisted for 14 LMG Life Sciences 2024 Americas Awards Finnegan Shortlisted for 14 LMG Life Sciences 2024 Americas Awards
July 18, 2024
LMG Life SciencesCommentary
Fed. Circ. OKs Boston Drug Developer's Patent Win Fed. Circ. OKs Boston Drug Developer's Patent Win
March 11, 2024
Law360Commentary
Too Many Cooks: Inventorship an Increasing Problem for Patent Counsel Too Many Cooks: Inventorship an Increasing Problem for Patent Counsel
November 21, 2023
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