GSK updates investors on AnaptysBio dostarlimab case

GSK plc, through its subsidiary TESARO, reports a procedural update in ongoing litigation with AnaptysBio over rights to the cancer drug dostarlimab (Jemperli).

Rhea-AI Filing Summary

GSK plc, through its subsidiary TESARO, reports a procedural update in ongoing litigation with AnaptysBio over rights to the cancer drug dostarlimab (Jemperli). The Delaware Chancery Court granted a motion by AnaptysBio to dismiss TESARO's claim for anticipatory breach. GSK notes that the ruling does not address the core contractual dispute and does not affect TESARO's remaining claim for declaratory judgment, which it plans to pursue at trial. Jemperli, the brand name for dostarlimab, is approved in over 35 countries for certain endometrial cancers, and GSK reports significant growth driven by label expansions and an ongoing clinical program in additional cancer types.

Key Figures

Jemperli approvals: over 35 countries

1 metrics

Jemperli approvals over 35 countries Approved for certain endometrial cancers

Key Terms

anticipatory breach, declaratory judgment, license agreement, endometrial cancers, +1 more

5 terms

anticipatory breach regulatory

"the motion to dismiss filed by AnaptysBio, Inc. against TESARO's claim for anticipatory breach"

declaratory judgment regulatory

"no impact on TESARO's remaining claim against AnaptysBio for declaratory judgment"

A declaratory judgment is a court ruling that states the legal rights or obligations of parties without ordering any specific action or awarding damages. It’s like a referee announcing which team’s rule applies before the game continues, removing uncertainty about how the law applies. For investors, such a ruling can reduce legal risk and clarify potential liabilities or contract interpretations that affect a company’s future cash flow and valuation.

license agreement financial

"requirements of the license agreement entered in March 2014 between the parties"

A license agreement is a contract where the owner of intellectual property, technology, a brand, or other rights gives another party permission to use those assets under specified conditions, usually for fees, royalties or other payments. For investors it matters because such deals create or limit predictable revenue streams, affect profit margins, transfer legal and commercial risk, and can determine how quickly a company can grow — like renting out a patented tool to earn steady income while keeping ownership.

endometrial cancers medical

"approved in over 35 countries for use in certain endometrial cancers"

forward-looking statements regulatory

"Cautionary statement regarding forward-looking statements GSK cautions investors that any forward-looking statements"

Forward-looking statements are predictions or plans that companies share about what they expect to happen in the future, like estimating sales or profits. They matter because they help investors understand a company's outlook, but since they are based on guesses and assumptions, they can sometimes be wrong.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What litigation update did GSK (GSK) disclose regarding AnaptysBio?

GSK reported that a Delaware Chancery Court granted AnaptysBio’s motion to dismiss TESARO’s anticipatory breach claim. GSK emphasized the ruling does not address the main contractual dispute and does not affect TESARO’s remaining declaratory judgment claim, which it intends to continue pursuing at trial.

Does the court ruling end the GSK–AnaptysBio dispute over dostarlimab?

No, the ruling does not end the dispute. It dismisses TESARO’s anticipatory breach claim but leaves TESARO’s separate declaratory judgment claim intact. GSK and TESARO plan to continue pursuing that remaining claim at trial as part of the broader contract disagreement.

What is the GSK–AnaptysBio dispute about in relation to dostarlimab?

The dispute stems from allegations by AnaptysBio that TESARO failed to meet certain requirements under a March 2014 license agreement and intends to revoke TESARO’s license for dostarlimab. TESARO contests these allegations and initiated litigation to clarify its rights under that license.

How important is Jemperli (dostarlimab) to GSK’s oncology portfolio?

Jemperli is a key oncology product for GSK, approved in over 35 countries for certain endometrial cancers. GSK reports significant growth for Jemperli, driven by label expansions in the US and EU, and is running a broad clinical trial program in additional cancer types.

What ongoing clinical development did GSK highlight for dostarlimab?

GSK highlighted a robust and ambitious clinical trial program evaluating dostarlimab in additional cancers, including rectal, colon, and head and neck cancers. This program builds on existing approvals in certain endometrial cancers and aims to explore broader potential uses for the medicine.

What caution did GSK provide about forward-looking statements in this update?

GSK cautioned that any forward-looking statements, including those about litigation and product development, involve risks and uncertainties. Actual results may differ materially due to factors described in the “Risk Factors” section of GSK’s Annual Report on Form 20-F for 2025 and other disclosures.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 6-K: How Foreign Companies Report to the SEC →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 04/27/2026 - 06:58 AM Learn about SEC filing dates

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of April 2026

Commission File Number 001-15170

GSK plc

(Translation of registrant's name into English)

79 New Oxford Street, London, WC1A 1DG

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F . . . .X. . . . Form 40-F . . . . . . . .

Issued: 27 April 2026, London UK

TESARO, a GSK subsidiary, provides update on AnaptysBio, Inc. litigation

GSK plc (LSE/NYSE: GSK) subsidiary, TESARO, Inc., confirms that the Delaware Chancery Court has granted the motion to dismiss filed by AnaptysBio, Inc. against TESARO's claim for anticipatory breach. The court's ruling does not address the merits of the principal contractual dispute between the parties and has no impact on TESARO's remaining claim against AnaptysBio for declaratory judgment. GSK and TESARO are firmly of the view that these allegations are entirely without merit and remain focused on pursuing that claim at trial.

TESARO initiated this litigation following allegations made by AnaptysBio that TESARO has not fulfilled certain requirements of the license agreement entered in March 2014 between the parties and that AnaptysBio intends to revoke TESARO's licence for dostarlimab.

Jemperli, which is the brand name for dostarlimab, is currently approved in over 35 countries for use in certain endometrial cancers, the most common gynaecologic cancer in the United States. GSK and TESARO have reported significant growth for Jemperli driven by label expansions in endometrial cancer, including in the US and EU. A robust and ambitious clinical trial programme to evaluate the potential use of dostarlimab in additional cancers, including rectal, colon and head and neck, is ongoing.

About GSK

GSK is a global biopharma company with a purpose to unite science, technology, and talent to get ahead of disease together. Find out more at www.gsk.com.

GSK enquiries
Media:	Tim Foley	+44 (0) 20 8047 5502	(London)
	Madison Goring	+44 (0) 20 8047 5502	(London)
	Kathleen Quinn	+1 202 603 5003	(Washington DC)
	Alison Hunt	+1 540 742 3391	(Washington DC)
Investor Relations:	Constantin Fest	+44 (0) 7831 826525	(London)
	James Dodwell	+44 (0) 20 8047 2406	(London)
	Mick Readey	+44 (0) 7990 339653	(London)
	Steph Mountifield	+44 (0) 7796 707505	(London)
	Sam Piper	+44 (0) 7824 525779	(London)
	Jeff McLaughlin	+1 215 751 7002	(Philadelphia)
	Frannie DeFranco	+1 215 751 3126	(Philadelphia)

Cautionary statement regarding forward-looking statements

GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Such factors include, but are not limited to, those described in the "Risk Factors" section in GSK's Annual Report on Form 20-F for 2025.

Registered in England & Wales:

No. 3888792

Registered Office:

79 New Oxford Street

London

WC1A 1DG

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorised.

GSK plc

(Registrant)

Date: April 27, 2026

By:/s/ VICTORIA WHYTE

--------------------------

Victoria Whyte

Authorised Signatory for and on

behalf of GSK plc