Tesaro, Inc. v. Anaptysbio, Inc.

IN THE COURT OF CHANCERY OF THE STATE OF DELAWARE

TESARO, INC., and )
TESARO DEVELOPMENT, )
LTD., )
)
Plaintiffs, )
)
v. ) C.A. No. 2025-1357-KSJM
)
ANAPTYSBIO, INC.,
)
Defendant. )

MEMORANDUM OPINION

Date Submitted: March 4, 2026
Date Decided: April 24, 2026

David E. Ross, Eric D. Selden, ROSS ARONSTAM & MORITZ LLP, Wilmington, DE;
Stephen J. Kastenberg, William B. Igoe, Elizabeth P. Weissert, Paul K. Ort,
BALLARD SPAHR LLP, Philadelphia, PA; Paul Spagnoletti, Brett M. McMahon,
Ryan W. Cooke, Marie Killmond, DAVIS POLK & WARDWELL LLP, New York, NY;
Counsel for Plaintiffs Tesaro, Inc. and TESARO Development, Ltd.

Ryan D. Stottmann, Brian P. Egan, Alec F. Hoeschel, Andrew Schoen, MORRIS,
NICHOLS, ARSHT & TUNNELL LLP, Wilmington, DE; Robert Counihan, Vanessa
Park-Thompson, Nicholas Klenow, FENWICK & WEST LLP, New York, NY;
Counsel for Defendant AnaptysBio, Inc.

McCORMICK, C.
The parties dispute their rights and obligations under a collaboration

agreement. The collaboration agreement contains a dispute resolution provision. On

October 7, 2025, the defendant sent notice to the plaintiffs teeing up the dispute as

required by the dispute resolution provision. The parties then agreed to a standstill

period to negotiate a resolution. Negotiations failed. On the day that the standstill

period expired, the parties filed mirror-image claims under the collaboration

agreement. The plaintiffs in this action also alleged that the defendant’s October 7

letter evidenced repudiation and asserted a claim of anticipatory breach.

The defendant has moved to dismiss the claim of anticipatory breach on two

grounds. First, the defendant argues that the complaint fails to state a claim.

Second, the defendant argues that the claim of anticipatory breach should be

dismissed under Delaware’s recently amended anti-SLAPP statute. This decision

grants the defendant’s motion to dismiss on the first ground—the plaintiffs failed to

allege that the defendant conveyed repudiation with unequivocal, positive, and

unconditional words or conduct, as required under Delaware law. This decision

rejects the defendant’s argument under the anti-SLAPP statute. To have a claim

struck under the anti-SLAPP statute, a movant must establish a nexus between the

cause of action and the protected activity. Here, the defendant has not established

the relevant nexus because the claim of anticipatory breach arises from the act of

repudiation, not the October 7 letter allegedly evidencing the repudiation.
I. FACTUAL BACKGROUND

The facts are drawn from the Complaint,1 the documents it incorporates by

reference, and facts subject to judicial notice.2

AnaptysBio, Inc. owns proprietary technology to discover antibodies used to

treat diseases. Tesaro, Inc. (together with its wholly owned subsidiary Tesaro

Development, Ltd., “Tesaro”) develops and commercializes transformational

medicines that improve, sustain, and extend the lives of cancer patients. Tesaro is a

wholly owned subsidiary of GlaxoSmithKline LLC (together with its non-Tesaro

affiliates, “GSK”). On March 10, 2014, AnaptysBio and Tesaro entered into a

Collaboration and Exclusive License Agreement (the “Collaboration Agreement”).3

The parties made at least three amendments to the Collaboration Agreement.4

The Collaboration Agreement governs the parties’ rights and obligations to a

cancer therapy called dostarlimab, which is marketed under the brand name

Jemperli. In July 2025, Tesaro and GSK told AnaptysBio that they had designed and

approved a Phase 3 clinical trial that would allow physicians to combine one of GSK’s

antibody drug conjugates with either dostarlimab or Keytruda.5 Keytruda is a

dostarlimab competitor. Because the clinical trial could enrich a dostarlimab

1 C.A. No. 2025-1357-KSJM, Docket (“Dkt.”) 1 (Compl.).

2 The court takes judicial notice of the stipulated status quo. Dkt. 6; see also In re
Gen. Motors (Hughes) S’holder Litig., 897 A.2d 162, 169 (Del. 2006) (“The trial court
may . . . take judicial notice of matters that are not subject to reasonable dispute.”).
3 Compl., Ex. 1 (Collaboration Agreement).

4 See Compl., Ex. 2 (Amendment No. 3).

5 Compl. ¶¶ 62–63. Keytruda is the brand name for pembrolizumab. Id. ¶ 2.

2
competitor or the drug it combines with, AnaptysBio viewed its launch as a breach of

Tesaro’s duty to seek dostarlimab’s “optimum commercial return” under the

Collaboration Agreement.6

Section 4.6(c) of the Collaboration Agreement contains a dispute resolution

provision, requiring that in the event that the parties dispute whether Tesaro was in

breach, the matter would be escalated to AnaptysBio’s and Tesaro’s senior

management. If those officers could not resolve the dispute within 30 days of

escalation, the parties could serve a notice of termination under Section 14.2 of the

agreement or file a lawsuit.7 Consistent with that provision, AnaptysBio sent a letter

to Tesaro and GSK on October 7, 2025. The letter states:

This letter provides notice of Tesaro’s material breaches
under Section 4.6(c) of the Collaboration Agreement and
initiates the 30-day dispute resolution process set forth
therein. Tesaro has breached the Collaboration Agreement
in at least three material ways. First, by knowingly
participating in past, ongoing, and imminent prohibited
clinical trials of [competitors]. Second, by failing to use
commercially reasonable efforts to obtain the optimum
commercial return for dostarlimab. And third, by
concealing development activities related to dostarlimab
from AnaptysBio. Tesaro’s conduct breaches at least
Sections 3.2(b), 4.6(b), 5.3(b), 5.3(e), and 8.1.8

6 Compl. Ex. 4 (“October 7 Letter”) at 7–8.

7 Amendment No. 3 § 4.6(c).

8 October 7 Letter at 2 (emphasis in original).

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AnaptysBio told Tesaro that it “expect[ed] the parties to work toward a

resolution of [Tesaro’s] material breaches by November 6, 2025,” which tracks the

Collaboration Agreement’s 30-day negotiation period.9

AnaptysBio further stated that “[i]f no resolution is reached within 30 days of

this notice, AnaptysBio will provide Tesaro its notice of termination under Section

14.2 and exercise its reversion rights under Section 8.2.”10 Section 8.2 of the

Collaboration Agreement governs the “reversion rights.” It provides that if Tesaro

fails to seek the “optimum commercial return” for dostarlimab, all licenses and rights

granted to Tesaro for dostarlimab IP terminate and Tesaro automatically grants

AnaptysBio an irrevocable, non-exclusive, worldwide license to patents and know-

how for producing and selling dostarlimab.11 Under Section 14.2, if a party sends a

notice of termination asserting breach, the allegedly breaching party has 60 days to

cure the breach.12

Tesaro responded on October 31, 2025 stating that if AnaptysBio pursued its

claims and tried to enforce its rights, Tesaro would reduce royalty payments it owes

AnaptysBio under the Collaboration Agreement and convert its licenses to

AnaptysBio’s IP into perpetual ones:

Please be advised that TESARO will not tolerate
AnaptysBio’s efforts to leverage its false claims into a
windfall. While TESARO is willing to discuss these
matters in good faith in accordance with the Collaboration

9 Id.; Amendment No. 3 § 4.6(c).

10 October 7 Letter at 2.

11 Collaboration Agreement §§ 8.1, 8.2, 14.4.

12 Id. § 14.2.

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Agreement’s dispute-resolution provision, TESARO also
reserves all rights under the Collaboration Agreement.
That includes TESARO’s explicit rights under Section
14.4(f) to convert its licenses into irrevocable, perpetual
licenses and to reduce royalty and milestone payments by
50% as a result of AnaptysBio’s threat to wrongfully
terminate the Collaboration Agreement and the licenses
granted to TESARO.13

Tesaro concluded its letter with a document retention demand.

AnaptysBio replied on November 3, 2025:

[Y]our clients’ threat to invoke Section 14.4(f) to convert
Tesaro’s licenses into irrevocable ones and reduce royalties
lacks credibility and is an improper attempt to scare
AnaptysBio from exercising its lawful rights. . . . Instead,
the apparent “breach” is no more than AnaptysBio
pursuing its rights under the Collaboration Agreement, so
the threat to invoke Section 14.4(f) seems designed only to
quell AnaptysBio from petitioning the courts to enforce its
rights. Such threats run afoul of clear Delaware law,
including its anti-SLAPP statute[.]14

In the cover email to AnaptysBio’s letter, AnaptysBio proposed extending the

30-day negotiation period before it expired.15 The parties agreed to extend the

negotiation period until November 20, 2025 at 5:59pm ET by way of a Standstill

13 Compl., Ex. 5 (“October 31 Response”) at 2.

14 Compl., Ex. 6 (“November 3 Letter”) at 2–3.

15 Dkt. 38 (“AnaptysBio Opening Br.”), Ex. 6 (“November 3 Email”). AnaptysBio
attached the November 3 Letter as an exhibit to the Complaint. See Compl. ¶ 87.
The November 3 Letter was attached to a cover email dated November 3. The court
can consider the November 3 Email along with the November 3 Letter because they
are part of the same communication, and considering both documents is necessary to
understand the complete context of the communication. See General Motors, 897 A.2d
at 169.

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Agreement.16 The Standstill Agreement’s purpose was “facilitate . . . good-faith

attempts to resolve the Disputes.”17

The parties filed mirror-image claims when the standstill period ended on

November 20, 2025.18 In this action, Tesaro asserts two Counts. In Count I, Tesaro

seeks a declaratory judgment and an injunction concerning the parties’ rights and

obligations under the Collaboration Agreement. In Count II, Tesaro claims that

AnaptysBio repudiated the Collaboration Agreement and committed anticipatory

breach through the October 7 Letter. Tesaro also filed a motion to expedite

proceedings and a motion for a temporary restraining order enjoining AnaptysBio

from terminating the Collaboration Agreement.19

Five days after the parties commenced their respective actions, the parties

signed and filed a stipulation to preserve the status quo through final judgment.20

Under the stipulation, AnaptysBio will neither send Tesaro a termination notice nor

attempt to exercise reversion rights.21 Similarly, Tesaro agreed to neither seek to

terminate the Collaboration Agreement nor attempt to reduce any amounts owed to

16 Compl. ¶¶ 12, 19, 88; AnaptysBio Opening Br., Ex. 8 (Standstill Agreement).

17 Standstill Agreement at 1.

18 See Compl.; C.A. No. 2025-1355-KSJM, Dkt. 1.

19 C.A. No. 2025-1357-KSJM, Dkt. 1.

20 Dkt. 6.

21 Id. ¶ 1(a).

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AnaptysBio or obtain perpetual licenses to its IP.22 The court granted the stipulation

the same day, preserving the status quo through final decision.23

AnaptysBio filed a partial motion to dismiss Count II for anticipatory breach

on December 30, 2025.24 AnaptysBio filed its motion under Court of Chancery Rule

12(b)(6) and 10 Del. C. §§ 6001–14, Delaware’s Uniform Public Expression Protection

Act (“UPEPA” or the “Act”). Section 6003 of UPEPA requires that any motion filed

under the Act be resolved within sixty days.25 The court thus expedited consideration

of the partial motion to dismiss. The parties briefed the motion and the court heard

oral arguments on March 4, 2026.26

II. LEGAL ANALYSIS

AnaptysBio has moved to dismiss Tesaro’s claim of anticipatory repudiation

under Rule 12(b)(6) and Section 6003 of UPEPA.

A. Rule 12(b)(6)

“[T]he governing pleading standard in Delaware to survive a motion to dismiss

is reasonable ‘conceivability.’”27 When considering a Rule 12(b)(6) motion, the court

22 Id. ¶ 1(b).

23 Id.

24 Dkt. 37.

25 10 Del. C. § 6008.

26 AnaptysBio Opening Br.; Dkt. 47 (“Tesaro Answering Br.”); Dkt. 52 (“AnaptysBio

Reply Br.”); Dkt. 74. Tesaro argued that AnaptysBio’s anti-SLAPP argument
automatically stayed discovery in all proceedings, including the related action filed
by AnaptysBio. The court rejected that argument in a bench ruling on March 6, 2026.
Dkt. 95.
27 Cent. Mortg. Co. v. Morgan Stanley Mortg. Cap. Hldgs. LLC, 27 A.3d 531, 536 (Del.

2011).

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must “accept all well-pleaded factual allegations in the [c]omplaint as true . . . , draw

all reasonable inferences in favor of the plaintiff, and deny the motion unless the

plaintiff could not recover under any reasonably conceivable set of circumstances

susceptible of proof.”28 The court, however, need not “accept conclusory allegations

unsupported by specific facts or . . . draw unreasonable inferences in favor of the non-

moving party.”29

“[R]epudiation [of a contract] is an outright refusal by a party to perform a

contract or its conditions[.]”30 Repudiation occurs when a party “takes an action that

constitutes a ‘significant and substantial alteration of both the present and

reasonably anticipated future relations created by the agreement.’”31 “Repudiation

may be accomplished through words or conduct.” 32 A promisor can repudiate by

communicating an outright refusal.33 A promisor can also repudiate by

communicating an “intent not to perform unless terms different from the original

28 Id. at 536 (citing Savor, Inc. v. FMR Corp., 812 A.2d 894, 896–97 (Del. 2002)).

29 Price v. E.I. du Pont de Nemours & Co., 26 A.3d 162, 166 (Del. 2011) (citing Clinton

v. Enter. Rent-A-Car Co., 977 A.2d 892, 895 (Del. 2009), overruled on other
grounds by Ramsey v. Ga. S. Univ. Advanced Dev. Ctr., 189 A.3d 1255 (Del. 2018)).
30 Clark v. State Farm Mut. Auto. Ins. Co., 131 A.3d 806, 811 (Del. 2016); CitiSteel

USA, Inc. v. Connell Ltd. P’ship, 758 A.2d 928, 931 (Del. 2000).
31 PAMI-LEMB I Inc. v. EMB-NHC, L.L.C., 857 A.2d 998, 1014 (Del. Ch. 2004)
(“PAMI”) (quoting Bali v. Christiana Care Health Servs., 1998 WL 685380, at *1 (Del.
Ch. Sep. 22, 1998)).
32 W. Willow-Bay Ct., L.L.C. v. Robino-Bay Ct. Plaza, LLC, 2009 WL 458779, at *5

(Del. Ch. Feb. 23, 2009).
33 Veloric v. J.G. Wentworth, Inc., 2014 WL 4639217, at *15 (Del. Ch. Sep. 18, 2014).

8
contract are met[.]”34 To survive dismissal, a complaint must allege that the

promisor conveyed repudiation with “unequivocal . . . positive, and unconditional”

words or conduct.35

AnaptysBio argues that the Complaint fails to state a claim for repudiation to

the extent Tesaro relies on AnaptysBio’s October 7 communication as a basis for the

claim. In the October 7 letter, AnaptysBio wrote to Tesaro to “provide[] notice of

Tesaro’s material breaches under Section 4.6(c) of the Collaboration Agreement” and

“initiate[] the 30-day dispute resolution process[.]”36 Although the letter expresses

an intent to send a “notice of termination,” AnaptysBio conditioned termination on

the parties failing to resolve their disagreement under the Collaboration Agreement’s

dispute resolution provision.37 This letter did not convey an unconditional intent to

never perform. Rather, the notice of termination was expressly conditioned on the

contract dispute process. Because it was expressly conditioned on a process designed

to eliminate the need for termination, the October 7 letter did not evidence

repudiation.

Tacitly conceding this point, Tesaro argues that a promisor can also repudiate

by communicating an “intent not to perform unless terms different from the original

34 PAMI-LEMB I, 857 A.2d at 1014; see also 13 Williston on Contracts § 39.40 (4th ed.

2025) (explaining that to constitute a repudiation, a “demand must be accompanied
by a clear expression of intent not to perform under any other interpretation”).
35 Veloric, 2014 WL 4639217, at *15 (internal quotations omitted).

36 October 7 Letter at 2.

37 Id. at 2, 9 (“Tesaro has 30 days under Section 4.6(c) to work toward a resolution of

these breaches with AnaptysBio.”).

9
contract are met.”38 According to Tesaro, the October 7 letter implied a demand that

Tesaro accept AnaptysBio’s terms or proposed concessions. Those concessions, in

Tesaro’s view, changed the terms of three aspects of the Collaboration Agreement—

the exclusivity provisions, the efforts provision, and the notice provision. 39

But a careful read of the letter reveals AnaptysBio’s good-faith disagreement

on the requirements of the Collaboration Agreement, not a unilateral demand to alter

those terms. The October 7 letter states that AnaptysBio sought to use the 30-day

dispute resolution period to resolve Tesaro’s breaches. And AnaptysBio describes, in

several factually laden pages, how Tesaro’s actions breached existing requirements

under the Collaboration Agreement.40 As to each issue raised in the letter,

AnaptysBio attempts to apply the terms of the Collaboration Agreement to Tesaro’s

conduct. At no point in the letter does AnaptysBio demand new terms or suggest that

it seeks to add additional obligations to those described in the Collaboration

Agreement. AnaptysBio did not express, in unequivocal, positive, and unconditional

words or conduct, that it would not perform unless Tesaro agreed to new terms and

conditions.

38 Tesaro Answering Br. at 18 (quoting PAMI-LEMB I, 857 A.2d at 1014).

39 Id. at 19–27.

40 October 7 Letter at 5–8.

10
Tesaro relies on two decisions of this court—PAMI-LEMB Inc. v. EMB-NHC,

L.L.C.41 and Darby Emerging Markets Fund, L.P. v. Ryan.42 Each case is

distinguishable.

PAMI-LEMB I does not support Tesaro’s position. That case concerned a

dispute between partners “over the interpretation and enforcement of identical

buy/sell provisions . . . governing distribution of partnership proceeds in a series of

partnership agreements.”43 The counterclaim-plaintiff invoked buy/sell provisions

constituting an offer to sell its interests to the counterclaim-defendant, Lehman

Brothers. The counterclaim-plaintiff argued that the sale price was $5.7 million.

Applying a different accounting measure, Lehman Brothers viewed the sale price as

$1.5 million. Lehman further stated that if the counterclaim-plaintiff refused to

accept the $1.5 million figure, Lehman would “litigate and assert that [counterclaim-

plaintiff] was entitled to nothing.”44 The court found repudiation there because the

repudiating party demanded that it pay less than what the contract expressly

required or, absent agreement to a reduced payment, it pay nothing at all. Here,

AnaptysBio invoked its right to start the contract’s dispute resolution process and

laid out the basis for its claims of breach. Tesaro cannot claim repudiation merely

because Tesaro disagrees with AnaptysBio’s contractual position.

41 857 A.2d 998 (Del. Ch. 2004).

42 2013 WL 6401131 (Del. Ch. Nov. 27, 2013).

43 PAMI-LEMB I, 857 A.2d at 1001.

44 Id. at 1013.

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Darby is similarly inapposite. That case concerned a put right under a

shareholder agreement that could be exercised in the event of a fundamental dispute

concerning the management of the business.45 After a dispute arose, and in the

course of “dispute resolution” negotiations, the defendants insisted that the plaintiff-

shareholder waive its put right as part of any resolution. 46 Upon conclusion of the

dispute-resolution period, the plaintiff-shareholder sued for anticipatory breach of

the shareholder agreement.47 This court held that the allegation that the defendants

would not perform “on the terms and conditions set forth” in the shareholder

agreement “support[s] a reasonable inference that Defendants have positively and

unconditionally repudiated their obligations to honor” the put right.48 Here,

AnaptysBio neither asked Tesaro to waive any rights nor said it would not comply

with its own duties. Rather, it invoked the contract dispute resolution process.49

Because the October 7 letter alone does not support a claim for repudiation,

Tesaro points to the November 3 Letter. Tesaro did not identify the November 3

45 Darby, 2013 WL 6401131, at *2.

46 Id. at *4.

47 See id. at *4, *12.

48 Id. at *11.

49 Tesaro cites to two other decisions that are similarly inapposite. See Tesaro
Answering Br. at 20, 30 (citing UbiquiTel Inc. v. Sprint Corp., 2005 WL 3533697 (Del.
Ch. Dec. 14, 2005) and EMSI Acquisition, Inc. v. Contrarian Funds, LLC, 2017 WL
1732369 (Del. Ch. May 3, 2017)). In UbiquiTel, the plaintiff alleged that the
repudiating party acknowledged that its conduct would violate duties to the plaintiff.
UbiquiTel, 2005 WL 3533697, at *7. And EMSI Acquisition did not address breach
of contract or repudiation at all. See generally EMSI Acquisition, 2017 WL 1732369.

12
Letter as a basis for its claim in the Complaint. 50 The letter does not evidence

repudiation in any event. There, AnaptysBio stated that “[n]othing in [Tesaro’s

response] changes [AnaptysBio’s] view” or will “dissuade AnaptysBio from exercising

its right to dostarlimab’s reversion.”51 A threat to exercise contractual rights in the

event of breach is not repudiation, even if that contractual right is reversion. Quite

the opposite—exercising contractual rights under an agreement requires affirming

that agreement.

Even assuming that AnaptysBio’s October 7 and November 3 supported a

claim for repudiation, the Collaboration Agreement provides a 60-day cure period.52

That period ran at least until December 6, 2025. Delaware law allows a party to

retract a repudiation, “nullifying” it and “placing the matter in its original position.” 53

A party may do so if the time for performance has not lapsed and the non-repudiating

party “treats the contract as still in force.”54 A request for specific performance

demonstrates “that the promisee treats the mutual obligations as being still in

force.”55 And continued performance by the alleged repudiator, including through

negotiations pursuant to a contract, constitutes revocation.56

50 See Compl. ¶¶ 106–12.

51 November 3 Letter at 1.

52 Collaboration Agreement § 14.2.

53 Carteret Bancorp, Inc. v. Home Gp., Inc., 1988 WL 3010, at *6 (Del. Ch. Jan. 13,

1988).
54 Id.

55 Id.

56 West Willow-Bay Ct., 2009 WL 458779, at *6 (holding that defendant “retracted”

repudiation by “resum[ing] negotiations”).

13
AnaptysBio continued to perform under the contract after the events Tesaro

claims constitute repudiation. Tesaro confirmed the Collaboration Agreement was

effective on November 20, 2025 by filing a motion to enjoin AnaptysBio from sending

a termination notice. Tesaro’s motion confirms that Tesaro treated the parties’

“mutual obligations as being still in force.”57 Tesaro stated that “Tesaro seeks . . . a

TRO enjoining AnaptysBio from terminating the Collaboration Agreement[.]”58 And

the parties reaffirmed that the contract remained effective when stipulating to

preserve the status quo.59 Under the stipulation, no party will “issue any notice of

termination” until a final judgment.60 Any repudiation stemming from AnaptysBio’s

October 7 or November 3 letters was effectively cured or revoked before the 60-day

cure period lapsed and before Tesaro treated the contract as terminated.

For these reasons, Count II of the Complaint fails to state a claim for

repudiation. AnaptysBio’s motion to dismiss under Rule 12(b)(6) is granted.

B. Anti-SLAPP Motion

On September 15, 2025, Delaware adopted UPEPA.61 The Uniform Law

Commission created that model act to enhance protections from strategic lawsuits

57 Carteret Bancorp, Inc., 1988 WL 3010, at *6.

58 Dkt. 1 (“Tesaro TRO Br.”) at 5.

59 Dkts. 4, 6.

60 Dkt. 6 ¶ 1(a)–(b).

61 See 10 Del. C. §§ 6001–14. The Delaware UPEPA is essentially a carbon copy of
the model act. Sections 6001–14 of UPEPA correspond with §§ 1–14 of the model act.

14
against public participation (“SLAPPs”).62 SLAPPs are meritless lawsuits brought to

“ensnare their targets in costly litigation that chills society from engaging in

constitutionally protected activity.”63

UPEPA provides procedural relief to those opposing a SLAPP claim. Section

6003 of UPEPA authorizes a “special motion” to dismiss a SLAPP claim.64 Motions

brought under Section 6003 are statutorily expedited.65 Because UPEPA entitles a

successful movant to costs, attorneys’ fees, and expenses, granting the Rule 12(b)(6)

does not obviate the need to resolve AnaptysBio’s anti-SLAPP motion.66

Section 6007(a) establishes the elements of a special motion under Section

6003. A special motion proceeds in three parts. First, the moving party must

“establish[] under § 6002(b) or (d) of this title that this chapter applies.”67 Second,

the responding party must fail to demonstrate that the challenged conduct is among

the carve-outs listed in Section 6002(c).68 Third, the moving party must show that its

anti-SLAPP argument has merit because the responding party failed to establish a

62 Unif. Pub. Expression Prot. Act, prefatory n. at 3 (Unif. L. Comm’n, Draft Oct. 2,

2020).
63 Id. at 1.

64 10 Del. C. § 6003.

65 Id. § 6005, 6008.

66 Id. § 6010(a)(1).

67 Id. § 6007(a)(1).

68 Id. § 6007(a)(2) (“The responding party fails to establish under § 6002(c) of this title

that this chapter does not apply[.]”).

15
prima facie case or state a claim, or the movant demonstrated based on the

undisputed facts that it would be entitled to summary judgment as a matter of law.69

The second and third parts of Section 6007(a) are not in play here. Tesaro does

not advance arguments regarding carve-outs under § 6002(c). And AnaptysBio has

demonstrated that Tesaro fails to state a claim for anticipatory repudiation. The

analysis thus hinges on the first part of Section 6007(a).

Courts have interpreted the first part of Section 6007(a) as imposing two

requirements. A movant must demonstrate that it engaged in a protected activity

under § 6002(b) or (d). The movant must also establish a nexus between the cause of

action and the protected activity—that is, that “the responding party’s suit arises

from the movant’s constitutionally protected activity.”70

69 Id. § 6007(a)(3) (“Either: the responding party fails to establish a prima facie case

as to each essential element of the cause of action; or the moving party establishes
that (1) the responding party failed to state a cause of action upon which relief can be
granted; or (2) there is no genuine issue as to any material fact and the moving party
is entitled to judgment as a matter of law on the cause of action or part of the cause
of action.” (cleaned up)).
70 Unif. Pub. Expression Prot. Act § 7 cmt. 2 (citing Thomas R. Burke, Anti-SLAPP

Litigation § 3.2 (2019)); see also id. (“[T]he mere fact that an action was filed after
protected activity took place does not mean the action arose from that activity for the
purposes of the anti-SLAPP statute. Moreover, that a cause of action arguably may
have been ‘triggered’ by protected activity does not entail it as one arising from such.”
(quoting Navellier v. Sletten, 52 P.3d 695, 708–09 (Cal. 2002))). As it did when
denying Tesaro’s request to stay proceedings, see Dkt. 95, the court relies on the
Uniform Law Commission’s official comments to the model act in interpreting
UPEPA. See Gibson v. Keith, 492 A.2d 241, 247–48 (Del. 1985) (finding official
commentary from drafters of a model act persuasive in interpreting the act as enacted
in the Delaware Code); Cannon v. Romeo Sys., Inc., 2025 WL 2848069, at *20 n.164
(Del. Ch. Oct. 7, 2025) (explaining that Delaware courts refer to the official comments
to the UCC in interpreting its counterparts codified in Delaware statutes).

16
The conduct at issue concerns AnaptysBio’s prelitigation communications—the

October 7 and November 3 letters. AnaptysBio argues that those communications

constituted protected activity under Section 6002(b)(2) and that the claim of

anticipatory breach arises from those communications. Even if the prelitigation

communications constitute protected activity,71 AnaptysBio fails to demonstrate the

requisite “arises from” nexus.

A cause of action “arises from” protected activity if the “conduct underlying the

[] cause of action” was “itself an act in furtherance of the right of petition or free

speech.”72 Put differently, “a claim may be struck only if the speech or petitioning

activity itself is the wrong complained of, and not just evidence of liability or a step

71 The court assumes this for the sake of argument without resolving the issue, which

is complicated. Section 6002(b)(2) of UPEPA makes any “[c]ommunication on an
issue under consideration or review in a legislative, executive, judicial,
administrative, or other governmental proceeding” protected activity. 10 Del. C. §
6002(b)(2). Courts have construed this provision to include prelitigation
communications. See Nirschl v. Schiller, 308 Cal. Rptr. 3d 338, 348 (Cal. Ct. App.
2023); Trinity Risk Mgmt., LLC v. Simplified Lab. Staffing Sols., Inc., 273 Cal. Rptr.
3d 831, 838–39 (Cal. Ct. App. 2021); see also Sheehan v. Assured P’rs, Inc., 2020 WL
2838575, at *16 (Del. Ch. May 29, 2020) (discussing the absolute litigation privilege).
But prelitigation communications “do not qualify as a protected activity if future
litigation is not anticipated, and is therefore only a ‘possibility’—and this is true even
if the communication is a necessary prerequisite to any future litigation.” Mission
Beverage Co. v. Pabst Brewing Co., LLC, 223 Cal. Rptr. 3d 547, 559 (Cal. Ct. App.
2017). Thus, not every communication sent in anticipation of litigation constitutes
protected activity. See Nirschl, 308 Cal. Rptr. 3d at 348.
72 Burke, supra, § 3.3 (emphasis in original) (internal quotation marks omitted) (first

quoting City of Cotati v. Cashman, 52 P.3d 695, 701 (Cal. 2002); then citing Equilon
Enters. v. Consumer Cause, Inc., 52 P.3d 685, 693 (Cal. 2002)); see also Park v. Board
of Trustees of California State Univ., 393 P.3d 905, 908 (Cal. 2017) (stating that a
movant satisfies the nexus requirement “when th[e] activity underlies or forms the
basis for the claim” (emphasis added)); Hastings Coll. Conservation Comm. v.
Faigman, 309 Cal. Rptr. 3d 451, 457–59 (Cal. Ct. App. 2023).

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leading to some different act for which liability is asserted.”73 The protected activity

must be the “injury-producing conduct.”74 Defamation claims present the

quintessential example. There, the protected activity is the act of speech, which

“itself is the wrong complained of” in the claim of defamation.75

There is a distinction between “speech that provides the basis for liability and

speech that provides evidence of liability.”76 A communication that serves merely as

evidence of a complained-of wrong is not itself the injury-producing conduct.

Mission Beverage Co. v. Pabst Brewing Co., LLC is instructive.77 There, a

brewing company sent a letter to one of its distributors terminating their distributor

agreement and commencing a statutory negotiation procedure to determine the fair

market value of the affected distribution rights.78 The distributor sued the brewing

company, alleging that the brewing company breached the contract by “attempting”

to terminate the agreement and seeking a declaratory judgment that there was no

valid termination of the agreement.79 The brewing company filed a motion to strike

the complaint under California’s anti-SLAPP statute.

73 Park, 393 P.3d at 907 (emphasis in original).

74 Laker v. Bd. of Trs. of Cal. State Univ., 244 Cal. Rptr. 3d 238, 266 (Cal. Ct. App.

2019) (citation modified).
75 See, e.g., Abir Cohen Treyzon Salo, LLP v. Lahiji, 254 Cal. Rptr. 3d 1, 4–6 (Cal. Ct.

App. 2019); Hecimovich v. Encinal Sch. Parent Tchr. Org., 137 Cal. Rptr. 3d 455, 467–
66 (Cal. Ct. App. 2012); see also Scott v. Metabolife Int’l, Inc., 9 Cal. Rptr. 3d 242, 253
(Cal. Ct. App. 2004) (“[D]efamation suits are a prime target of SLAPP motions.”).
76 Park, 393 P.3d at 909.

77 223 Cal. Rptr. 3d 547 (Cal. Ct. App. 2017).

78 Id. at 552.

79 Id. at 553.

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A California appellate court affirmed the trial court’s denial of the motion. The

appellate court held that the distributor’s claims challenged the brewing company’s

attempt to terminate the distributor agreement, but the brewing company’s letter

“merely communicated [the] decision to terminate, [and] that communication does

not convert [the distributor’s] suit into one arising from such speech.”80 The court

stated: “[The distributor’s] claims attack [the brewing company’s] decision to

repudiate the Agreement; as noted above, the fact that the repudiation was

communicated through a letter does not alter the basis of those claims.”81

So too here. The wrong complained of in Tesaro’s claim of anticipatory breach

is AnaptysBio’s supposed repudiation. The protected activities—the prelitigation

communications—are not the alleged wrong, they are at most evidence of it.

AnaptysBio attempts to distinguish Mission Beverage because there the

defendant “‘attack[ed] [defendant’s] decision to repudiate the agreement,’—not the

defendant’s protected communications.”82 By contrast, here, Tesaro claims to rely on

the October 7 and November 3 the communications to show that “AnaptysBio’s

unequivocal and protected statements caused the purported repudiation.”83 But this

is the precise argument that the Mission Beverage court rejected. The nexus

requirement of Section 6003 motions requires that the protected activity be the cause

of the injury. How a party communicates repudiation does not render the

80 Id. at 557 (citation modified).

81 Id. at 558.

82 AnaptysBio Reply Br. at 27 (quoting Mission Beverage, 223 Cal. Rptr. 3d at 702).

83 Id. (emphasis in original).

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communication the injury-producing action. Put differently, no matter how the

decision to repudiate was conveyed, the injury in a claim for anticipatory breach is

the act of repudiation—not the way it was communicated.

III. CONCLUSION

AnaptysBio’s Rule 12(b)(6) motion is granted. AnaptysBio’s Section 6003

motion is denied. Tesaro argues that it is entitled to fees and costs it incurred in

responding to AnaptysBio’s anti-SLAPP motion.84 UPEPA permits a successful

nonmoving party to recover fees and costs if the motion was “frivolous or filed solely

with intent to delay the proceeding.”85 That was not the case here. This is a case of

first impression in Delaware courts, and the motion was filed and argued in good

faith. Each party must bear its own fees and costs.

84 Tesaro Answering Br. at 55–56.

85 10 Del. C. § 6010(a)(2).

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