The Delaware Chancery Court dismissed Tesaro's anticipatory breach of contract claim against AnaptysBio Inc. (NASDAQ: ANAB), preserving current royalty rates for the cancer drug Jemperli and rejecting Tesaro's request for royalty reduction.

The court ruled that Anaptys had not repudiated its collaboration agreement with Tesaro, a subsidiary of GSK, which governs development and commercialization of Jemperli. The decision confirms that Tesaro's claim was insufficiently pleaded.

Dan Faga, Anaptys president and chief executive officer, said the ruling validates the company's efforts to protect contractual rights to the Jemperli royalty stream for shareholders.

Under the 2014 collaboration agreement, Anaptys receives royalties on Jemperli sales at rates of 8% for net sales below $1 billion, 12% for sales between $1 billion and $1.5 billion, 20% for sales between $1.5 billion and $2.5 billion, and 25% for sales above $2.5 billion.

Anaptys has filed its own complaint alleging Tesaro breached multiple provisions of the collaboration agreement, including exclusivity duties by engaging with competitive therapeutics, diligence duties requiring pursuit of Jemperli's "optimum commercial return," and notice requirements for clinical trial plans.

If Tesaro is found in breach of any provision, Anaptys claims entitlement to reversion of Jemperli rights under the agreement. The trial is scheduled for July 14-17, 2026.

The royalty term extends through patent expiration, which occurs in 2035 in the United States, 2036 in the European Union, and 2037 in Japan, with potential extensions to 2038.