Sonnet BioTherapeutics Successfully Completes First Safety Review of SON-1010 in Combination with Trabectedin in Certain Sarcomas

SON-1010 is being studied as a combination therapy with trabectedin (Yondelis^®), the first FDA-approved treatment for two types of advanced soft tissue sarcoma after failure of standard chemotherapy, due to the potential for immune mechanism synergies and enhancement of progression-free survival (PFS)

The Safety Review Committee found no unexpected toxicities in early dosing of SON-1010 in the first 7 patients at the maximum tolerated dose (MTD), paving the way for full enrollment of up to 18 patients

The annual review showed extended safety of SON-1010 monotherapy at the MTD with clinical benefit in 83% of patients at that dose, including confirmed partial response (PR) in a patient with clear cell sarcoma

Potential to improve upon the $2.1B trabectedin global market opportunity¹ and treatment of sarcomas, an area of significant unmet medical need

Management releases “What This Means” segment discussing the Safety Review Committee findings;

Excerpt from the Press Release:

PRINCETON, N.J., March 26, 2025 (GLOBE NEWSWIRE) — Sonnet BioTherapeutics Holdings, Inc. (NASDAQ:SONN) (the “Company” or “Sonnet”), a clinical-stage company developing targeted immunotherapeutic drugs, today announced positive findings from the first safety review of the expansion cohort in its Phase 1 SB101 clinical trial evaluating SON-1010, the Company’s proprietary version of recombinant human interleukin-12 (rhIL-12) configured using genetic fusion to Sonnet’s Fully Human Albumin Binding (F_HAB^®) platform, in combination with trabectedin (Yondelis^®) in adult patients with advanced leiomyosarcoma (LMS) or liposarcoma (LPS). The expansion cohort builds on the successful completion of monotherapy dose escalation and assignment of the SON-1010 maximum tolerated (MTD) dose of 1200 ng/kg. Additionally, the Company announced the release of a Virtual Investor “What This Means” segment to discuss the first safety review findings, which is now available here.

The SB101 Safety Review Committee (SRC) met to evaluate the initial status of the patients in the expansion cohort, all of whom are receiving the SON-1010/trabectedin combination, as enrollment continues. After an average treatment of slightly over two months, one patient progressed and the other six are tolerating treatment. Adverse events (AEs) considered to be related to either drug have all been mild or moderate, suggesting that the two drugs do not appear to be adversely impacting each other. The annual review including all 30 patients dosed to date showed that common AEs considered related to SON-1010 monotherapy or in combination included fatigue, fever, chills, and myalgia in 15% or more; moderate fatigue was the only related AE in 2 or more of the patients treated with trabectedin to date. Full enrollment of the combination cohort will provide an opportunity to evaluate statistical evidence of benefit in the response using the standard RECIST paradigm, which may also confirm synergy. Meanwhile, five of the six patients in the SON-1010 high-dose monotherapy group (83%) showed stable disease at 4 months and four continue on trial at 6 months with no new safety concerns. The partial response (PR) in one of those patients persists, confirming the potential for benefit of SON-1010 monotherapy at the MTD in this small cohort. Overall, 13 of the 24 patients studied during SON-1010 dose escalation (54%) had evidence of monotherapy clinical benefit.

Click the button below to read the entire Press Release:

Continue Reading The Press Release