Sonnet BioTherapeutics expands clinical evaluation of SON-1010 dose escalation

Sonnet BioTherapeutics (SONN) announced the expansion of its clinical study of patients with platinum-resistant ovarian cancer, PROC, SB221. SB221 is a Phase 1b/2a dose-escalation and proof-of-concept study of the combination of SON-1010, IL12-FHAB, with atezolizumab, which is provided by Genentech, a member of the Roche Group (RHHBY). Enrollment of the expansion group using the highest maintenance dose from the monotherapy study has been completed, providing an opportunity to study the safety of the combination in a larger population and get a preliminary efficacy readout later this year. A second partial response based on GCIG criteria was recently observed at the 2-month timepoint and confirmed by RECIST criteria 2 months later in a patient with PROC at that dose. Thus, 2 of the 3 patients at the E6 dose of SON-1010 had a significant tumor response. Given the strong safety profile at the top dose, the Safety Review Committee recommended adding an E7 cohort using a maintenance dose of 1500 ng/kg to study its safety and effectiveness before proceeding to the randomized Phase 2a portion, which will evaluate patients with PROC at one of the two highest doses compared to the standard of care.