MNG Bio LLC v. Moderna Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: mNG BIO, LLC (Texas)
  • Defendant: MODERNA INC., ModernaTX, Inc. (Delaware)
  • Plaintiff’s Counsel: TROUTMAN PEPPER LOCKE LLP
• Case Identification: 1:26-cv-10074, D. Mass., 01/08/2026
• Venue Allegations: Plaintiff alleges venue is proper in the District of Massachusetts because Defendants have regular and established places of business in the district, including their principal places of business, and have committed acts of infringement there.
• Core Dispute: Plaintiff alleges that Defendant’s use of the mNeonGreen fluorescent protein in a research assay during the development and testing of its Spikevax COVID-19 vaccine infringes a patent related to the engineered protein.
• Technical Context: The dispute centers on monomeric fluorescent proteins, which are critical molecular biology tools used as biomarkers or tags to visualize, track, and quantify biological processes in research and drug development.
• Key Procedural History: The complaint notes that Defendants previously initiated litigation in the same district against a third party (Pfizer Inc.) relating to the Spikevax vaccine, which Plaintiff presents as evidence of Defendants purposefully availing themselves of the Massachusetts courts.

Case Timeline

Date	Event
2012-07-24	’221 Patent Priority Date
2014-04-28	’221 Patent assigned by inventors to Allele Biotechnology
2019-03-05	U.S. Patent No. 10,221,221 Issues
2020-03-16	Moderna initiates Phase I clinical trial for its COVID-19 vaccine
2020-05-20	Moderna initiates Phase II clinical trial for its COVID-19 vaccine
2020-07-20	Moderna initiates Phase III clinical trial for its COVID-19 vaccine
2020-12-18	Moderna receives Emergency Use Authorization from the FDA
2022-01-31	FDA approves Moderna's Biologics License Application
2026-01-06	’221 Patent assigned by Allele to mNG BIO, LLC
2026-01-08	Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 10,221,221 - Monomeric yellow-green fluorescent protein from cephalochordate

• Patent Identification: U.S. Patent No. 10,221,221 (“the ’221 Patent”), “Monomeric yellow-green fluorescent protein from cephalochordate,” issued March 5, 2019.

The Invention Explained

• Problem Addressed: The patent addresses limitations of existing fluorescent proteins used in biological imaging (Compl. ¶31; ’221 Patent, col. 1:41-54). A naturally occurring, brightly fluorescent protein derived from the cephalochordate Branchiostoma lanceolatum (lanYFP) exists as a tetramer—a complex of four protein units—which makes it large and often unsuitable for use as a precise biological tag in genetic engineering (Compl. ¶31).
• The Patented Solution: The invention is an engineered, non-naturally occurring version of the lanYFP protein that has been modified to be "monomeric," meaning it functions as a single unit (’221 Patent, Abstract; col. 2:1-3). This modification was achieved through computational modeling and targeted mutations to disrupt the interfaces that cause the natural protein to form tetramers, resulting in a smaller, more versatile tool that retains high brightness for use as a "biomarker and/or protein fusion tag" (’221 Patent, col. 1:31-35, col. 6:1-3).
• Technical Importance: The development of a bright and stable monomeric fluorescent protein provides researchers with a more effective tool for tagging and observing specific proteins or cellular components without the disruption that a larger, multi-unit tag might cause (Compl. ¶31).

Key Claims at a Glance

• The complaint alleges infringement of one or more claims of the ’221 Patent, including claims 1-5 (Compl. ¶33, ¶64). Independent claim 1 is central to the dispute.
• Independent Claim 1:
  • A non-naturally occurring isolated monomeric or dimeric lanYFP fluorescent protein
  • comprising a polypeptide having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 1
  • wherein the protein comprises at least one mutation selected from a specified group of 21 possible mutations.
• The complaint generally alleges infringement of "one or more claims," which may encompass dependent claims (Compl. ¶76).

III. The Accused Instrumentality

Product Identification

• The accused instrumentality is not the Spikevax vaccine itself, but rather Defendants' alleged use of the patented mNeonGreen protein in a "fluorescent 'FRNTmNG' assay" (Compl. ¶5, ¶34). This assay was allegedly used throughout the pre-clinical and clinical development, as well as post-approval testing, of Moderna's COVID-19 vaccine candidates (Compl. ¶6, ¶35).

Functionality and Market Context

• The complaint alleges the FRNTmNG assay is a "key test for neutralizing antibodies against COVID-19 infection" that uses a "SARS-CoV-2-mNG reporter virus" (Compl. ¶5, ¶34). This reporter virus incorporates the mNeonGreen protein, allowing researchers to rapidly measure the effectiveness of vaccine candidates in neutralizing the virus (Compl. ¶58). The complaint alleges this tool was "instrumental" in helping Moderna select its most potent vaccine candidate, complete clinical trials, and secure FDA authorization (Compl. ¶8, ¶35). The complaint includes a visual reference from an exhibit that depicts the generation of the reporter virus, stating "mNeonGreen was incorporated into this cDNA to make a reporter virus" (Compl. ¶58, referencing Ex. D at Fig. 3A).

IV. Analysis of Infringement Allegations

’221 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A non-naturally occurring isolated monomeric or dimeric lanYFP fluorescent protein…	Defendants are alleged to have used "mNeonGreen," which the complaint describes as an engineered, monomeric protein derived from the naturally tetrameric lanYFP.	¶31, ¶64	col. 1:22-30
…comprising a polypeptide having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 1…	The complaint alleges that the mNeonGreen protein in the construct used by Moderna is "identical to SEQ ID NO:1 of the '221 patent," which meets the at least 95% identity threshold.	¶61, ¶63	col. 7:20-28
…wherein the protein comprises at least one mutation selected from the group consisting of: F15I, R25Q, A45D… [and 18 others]	The complaint alleges that the protein used by Moderna has "at least one" of the mutations recited in claim 1. By alleging identity to SEQ ID NO: 1, the complaint implicitly alleges the presence of all 21 mutations.	¶63	col. 6:40-53

• Identified Points of Contention:
  • Scope Questions: A central legal dispute may involve the applicability of the "safe harbor" provision of 35 U.S.C. § 271(e)(1), which exempts certain uses of patented inventions related to developing and submitting information for federal regulatory approval. The complaint appears to preemptively argue against this defense by asserting that the use was not solely for FDA submission and included "Post-Approval Marketing Use" to compete with other vaccines (Compl. ¶37, ¶57, ¶62). This framing raises the question of whether the use of a patented research tool to develop a therapeutic product constitutes infringement or falls under a statutory exemption.
  • Technical Questions: A primary factual question will be the verification of the accused protein's composition. The complaint alleges that the mNeonGreen protein used in the assay is "identical to SEQ ID NO:1 of the '221 patent" (Compl. ¶61). This raises the evidentiary question of what proof will be offered to demonstrate that the protein utilized in the third-party assay employed by Moderna possesses the specific amino acid sequence and monomeric properties required by the asserted claims.

V. Key Claim Terms for Construction

• The Term: "monomeric ... protein"

• Context and Importance: The invention's core purpose was to convert a naturally occurring tetrameric protein into a monomeric one for improved utility as a biological tag. The definition of "monomeric" is therefore critical to determining both the scope of the claim and whether the accused protein infringes.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The patent specification does not provide a precise structural or quantitative definition of "monomeric." Parties may argue for a functional definition, suggesting the term covers any protein that does not self-associate in a way that materially interferes with its function as a fluorescent tag in cellular imaging.
  • Evidence for a Narrower Interpretation: The patent explicitly references experimental results, stating that "size exclusion chromatography revealed that these proteins are tetramers" while the invention, mNeonGreen, is a "monomer" (’221 Patent, col. 2:62-65, Fig. 1). Parties may argue the term should be construed in light of this demonstrated physical behavior, tying its meaning to the specific elution profile shown in Figure 1.

• The Term: "lanYFP fluorescent protein"

• Context and Importance: This term anchors the claimed invention to a specific protein originating from the Branchiostoma lanceolatum species. Its construction defines the universe of proteins to which the claimed mutations and characteristics apply.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: This interpretation would likely cover any fluorescent protein derived from the foundational lanYFP amino acid sequence, as identified in the patent's sequence listing (e.g., SEQ ID NO: 5).
  • Evidence for a Narrower Interpretation: Parties may argue that the term should be limited to proteins that are not only derived from lanYFP but also retain its characteristic yellow-green fluorescence spectrum, as described in the patent (’221 Patent, col. 6:54-57).

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement, stating that Defendants encouraged third parties, such as those involved in clinical studies, to use the infringing mNeonGreen assay (Compl. ¶79). It also pleads contributory infringement, alleging that Defendants' use of mNeonGreen is a material part of the invention that is not a staple article of commerce suitable for substantial noninfringing use (Compl. ¶80).
• Willful Infringement: The complaint alleges that Defendants had knowledge of the patented technology and the patent itself. It bases this on a 2013 scientific publication by the inventors that allegedly disclosed that a patent had been filed for mNeonGreen (Compl. ¶69). It further alleges Defendants had actual knowledge of the issued ’221 Patent and the "obvious risk of infringement" since at least the start of clinical trials in early 2020 (Compl. ¶70).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of statutory scope: does Moderna's use of the patented mNeonGreen protein within a research assay to develop and test its Spikevax vaccine constitute commercial infringement, or does it fall within the 35 U.S.C. § 271(e)(1) "safe harbor" exemption for activities reasonably related to seeking FDA approval? The plaintiff's allegations of "post-approval marketing use" suggest this will be a central point of contention.
• A key evidentiary question will be one of technical identity: can the plaintiff prove that the "mNeonGreen" protein used in the neutralization assay, which was developed by a third party and used by Moderna, is the specific, engineered polypeptide defined by the sequence identity and mutation limitations of claim 1 of the ’221 patent?