In the heart of San Diego’s thriving biotech community, a high-stakes legal battle is playing out between AnaptysBio and Tesaro, a subsidiary of pharma giant GSK. At issue is whether Anaptys properly adhered to a Collaboration and Exclusive License Agreement that governs royalties on sales of Jemperli, the cancer immunotherapy co-developed by the two companies. As litigation heats up in Delaware Chancery Court, Anaptys has filed a motion to dismiss Tesaro’s claim of anticipatory breach, arguing that its conduct has been fully in line with the contract’s terms.
Tesaro surprised many observers when, on November 20, 2025, it filed its own lawsuit accusing Anaptys of repudiating the license agreement. That complaint, lodged without prior notice while settlement talks were ongoing, seeks a declaration that Tesaro has not breached and that Anaptys forfeited its rights by allegedly threatening not to honor the pact. In effect, Tesaro claims Anaptys scoped out an exit strategy before raising concerns about royalty payments and development milestones.
Rather than back down, Anaptys flipped the script by filing its own complaint in Delaware Chancery Court. There, it accused Tesaro of materially breaching the collaboration terms and charged GSK with tortious interference. This strategic counterattack set the stage for December 30, 2025, when Anaptys formally moved to dismiss Tesaro’s anticipatory breach claim. The crux of its argument is simple: asserting your contractual rights cannot legally amount to refusing to perform on the contract.
One particularly intriguing aspect of Anaptys’s motion is its reliance on Delaware’s anti-SLAPP statute, designed to shield parties from meritless lawsuits intended to stifle lawful speech or legal action. By framing Tesaro’s suit as a naked attempt to intimidate Anaptys into silence over royalty disputes, the biotech hopes to have the anticipatory breach claim thrown out swiftly and at Tesaro’s expense.
Behind the courtroom theatrics lies a tightly held prize—royalty revenue from Jemperli sales as the therapy gains market traction. With a trial set for July 14–17, 2026, both sides stand to gain or lose millions, not only in immediate payments but in the perceived value of collaboration agreements across the industry. A win for Anaptys could embolden smaller biotech firms negotiating with big pharma, while a Tesaro victory would warn partners that early legal action remains an available bargaining tool.
From a strategic standpoint, this clash highlights the complex dance between innovation and corporate power. Anaptys’s motion to dismiss underscores how modern biotech companies can use sophisticated legal defenses—like anti-SLAPP—to protect their interests. At the same time, Tesaro’s preemptive lawsuit illustrates the lengths to which a deep-pocketed parent like GSK might go to control the narrative and preclude challenges down the road.
As we await the court’s ruling on the motion and the subsequent summer trial, the Anaptys–Tesaro dispute serves as a reminder that in today’s biotech landscape, scientific breakthroughs and shareholder returns frequently intersect in the courtroom. Beyond the fate of Jemperli royalties, this case may set important precedents for how collaboration agreements are enforced, how disputes are resolved, and how smaller innovators guard their breakthroughs against corporate heavyweights. In the end, both sides will learn whether their legal maneuvers shine as brightly as the next generation of immunotherapies they hope to bring to patients.
