Sonnet BioTherapeutics Expands Phase 1 SB101 Trial: Combining SON-1010 and Trabectedin for Certain Sarcomas

Sonnet BioTherapeutics Holdings, Inc. (NASDAQ:SONN), a clinical-stage company specializing in targeted immunotherapeutic drugs, has announced an expansion of its Phase 1 SB101 clinical study. The expansion aims to evaluate the combination of SON-1010 (IL12-FHAB) with trabectedin (Yondelis®) in adult patients with advanced solid tumors, specifically focusing on certain sarcomas. This strategic move follows the successful completion of monotherapy dose escalation and seeks to explore the immune-oncology impact of SON-1010 at its maximum tolerated dose (MTD) of 1200 ng/kg in combination with trabectedin.



The expansion of the SB101 trial represents a significant advancement in the treatment of soft-tissue sarcomas (STS), targeting an identified market opportunity. Trabectedin, an approved chemotherapeutic drug for certain advanced STS, has shown promise in combination with SON-1010, a proprietary version of recombinant human interleukin-12 (rhIL-12) configured using Sonnet's Fully Human Albumin Binding (FHAB®) platform. This combination has the potential to enhance the therapeutic window of trabectedin, potentially improving progression-free survival (PFS) in some of the largest cohorts of patients with STS.



The SB101 trial will enroll up to 18 patients with unresectable, metastatic liposarcoma or leiomyosarcoma in an open-label, single-arm expansion cohort. Patients will be treated with SON-1010 in combination with the standard 21-day trabectedin cycles, alternating the dosing of the two drugs. This number of subjects may be needed to see a statistical benefit in the response using the standard RECIST paradigm. The primary outcome measures for the Phase 1 SB101 trial are the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of SON-1010, with the MTD established at 1200 ng/kg.

The combination of SON-1010 and trabectedin has the potential to enhance progression-free survival (PFS) in patients with STS by optimizing the synergistic effects of the two mechanisms of action. The alternating dosing schedule allows for an enhanced local immune response in the tumor microenvironment (TME), potentially leading to better tumor control and delayed disease progression. This strategic positioning of Sonnet BioTherapeutics in the STS space, along with the potential for a larger Phase 2 study, could significantly impact the company's valuation and investment potential.



In conclusion, Sonnet BioTherapeutics' expansion of the Phase 1 SB101 trial to evaluate the combination of SON-1010 and trabectedin in certain sarcomas represents a strategic advancement in the treatment of soft-tissue sarcomas. This combination has the potential to enhance the therapeutic window of trabectedin, potentially improving progression-free survival (PFS) in patients with STS. The strategic positioning of Sonnet BioTherapeutics in the STS space, along with the potential for a larger Phase 2 study, could significantly impact the company's valuation and investment potential.