London, Jan 11, 2026, 08:35 GMT — The market has closed.
- GSK shares slipped 0.3% on Friday as a U.S. royalty dispute over the cancer drug Jemperli resurfaced.
- With the JPM healthcare conference on the horizon, investors are closely monitoring for any hints of deal discussions or updates on the pipeline
- GSK is due to release its full-year results on Feb. 4
Shares of GSK plc face fresh legal uncertainty on Monday after AnaptysBio moved to dismiss part of a contract claim related to royalties for the cancer drug Jemperli. On Friday, GSK slipped 0.26% to 1,886 pence, just shy of its 52-week peak at 1,909.5. Technical traders are eyeing the 1,830 pence level, close to the 200-day moving average, as a key support zone.
Why it matters now: the royalty dispute comes at a critical moment, with healthcare investors bracing for a busy news week in San Francisco and GSK’s reporting schedule getting squeezed. GSK confirmed that its chief scientific officer Tony Wood will be at the J.P. Morgan Healthcare Conference on Jan. 13, followed by the release of its full-year and fourth-quarter results on Feb. 4.
The deal backdrop is noisy too. At the same conference, bankers have been pitching a 2026 rebound in big-ticket healthcare mergers, and Reuters reported investors will be looking to GSK’s new CEO for any hint of how aggressive he wants to be. “That has made people dust off the playbook on the art of the possible,” Jeremy Meilman, JPMorgan’s global co-head of healthcare investment banking, said. 1
In the Jemperli case, AnaptysBio filed a partial motion to dismiss a claim brought by GSK’s oncology division, Tesaro, which alleges the biotech violated a 2014 agreement related to the drug’s development and sales. The trial is scheduled for July 14–17, 2026. The court is expected to rule on the dismissal motion by early March, according to Reuters. 2
In November, Tesaro filed a lawsuit against AnaptysBio in Delaware, claiming the right to terminate the deal and stop royalty and milestone payments. AnaptysBio hit back with a countersuit, alleging Tesaro violated exclusivity terms by participating in trials for competing PD-1 drugs, including Merck’s Keytruda, Reuters reported.
A PD-1 inhibitor is an immunotherapy that blocks a “checkpoint” some tumours exploit to dodge the immune system. The market’s crowded, so even small shifts in incentives can alter how aggressively companies pursue new indications for these drugs.
GSK this week reported positive late-stage results for its experimental chronic hepatitis B drug bepirovirsen. But analysts remain cautious, saying they need the full dataset before assessing its market potential. Jefferies’ Michael Leuchten called the phase-three data “encouraging,” noting the consistency could point to blockbuster status. 3
That combination — legal uncertainty in oncology and investors demanding more clarity on pipeline implications — makes the stock prone to sudden moves on minor updates. Even if GSK offers scant details, traders are set to parse conference remarks for clues.
One risk: the Jemperli litigation might drag on, leaving the market stuck with uncertainty over the final royalty rate for years. On another front, if upcoming bepirovirsen data disappoints compared to expectations, what once seemed like a “promising” headline could shrink into a modest commercial gain.
