Health care stocks were mixed premarket Thursday, with the State Street Health Care Select Sector SPDR ETF (XLV) up 0.3% and the iShares Biotechnology ETF (IBB) 0.2% lower.

Rezolute (RZLT) shares were down more than 88% after the company said its phase 3 sunRIZE study evaluating ersodetug in patients with congenital hyperinsulinism did not meet its primary and key secondary endpoints.

Sarepta Therapeutics (SRPT) stock was down nearly 7% after the company said it has negotiated exchange agreements with a limited number of holders of its 1.25% convertible senior notes due 2027.

IDEAYA Biosciences (IDYA) shares were up nearly 3% after the company said it has completed its targeted full enrollment of 435 patients in the phase 2/3 trial evaluating darovasertib in combination with Pfizer's (PFE) crizotinib for the treatment of metastatic uveal melanoma, a form of ocular cancer.