US-based biotechnology company Sonnet BioTherapeutics has reported positive safety outcomes from a Phase Ib/IIa trial of high-dose SON-1010 (IL12-FHAB) in combination with Genentech’s atezolizumab in adults with advanced solid tumours or platinum-resistant ovarian cancer (PROC).
The Safety Review Committee (SRC) has given positive feedback for the two-part SB221 trial, allowing it to progress to the expansion phase to assess the combination’s preliminary effect at the maximum tolerated dose (MTD).
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This will be followed by a Phase IIa randomised comparison of the therapy against the standard of care in PROC subjects.
SB221 was structured to evaluate the combination’s tolerability, pharmacodynamics (PD) safety and pharmacokinetics (PK).
A total of 19 subjects with PROC were treated in the study’s dose escalation phase, with one subject registering a partial response at the highest dose.
All the subjects enrolled in the trial are understood to have advanced solid tumours, while all participants at the higher doses have PROC, including those who enrolled in a final 1200ng/kg dose-escalation cohort.
The SB221 trial employed a ‘desensitising’ first dose (300ng/kg) strategy to mitigate toxicity while enabling higher maintenance doses.
The SRC’s assessment of the trial noted that the most common adverse events were fevers, gastrointestinal symptoms and fatigue, without any dose-limiting toxicity or cytokine release syndrome observed.
Sonnet BioTherapeutics chief medical officer Richard Kenney said: “We are encouraged by the topline safety data and very pleased with the ovarian cancer PR in the Phase Ib portion of the SB221 study.
“Given the history of safety concerns with rhIL-12, it is exciting to see higher doses of SON-1010 demonstrating minimal toxicity when used in combination with atezolizumab.”
SON-1010 is Sonnet BioTherapeutics’ lead programme and is designed to treat solid tumours, ovarian cancer and certain types of sarcoma.
Earlier this year, the company expanded its Phase I SB101 trial of SON-1010 for patients with advanced solid tumours.
