QBiotics Group Limited has announced promising results from Stage 1 of its Phase IIa clinical trial evaluating tigilanol tiglate in patients with advanced soft tissue sarcoma (STS), achieving an 80% objective response rate in injected tumors. The trial, conducted at Memorial Sloan Kettering Cancer Center, demonstrated significant clinical activity in this challenging-to-treat cancer.
Strong Efficacy Signals in Rare Cancer
The QB46C-H07 trial enrolled 11 patients with advanced or metastatic STS, with 10 patients forming the evaluable population for response analysis. Eight out of 10 evaluable patients achieved either complete ablation (100% reduction in volume) or partial ablation (≥30% reduction in volume) of treated tumors, meeting the primary endpoint.
At the tumor level, 22 of 27 (81%) injected tumors across all patients showed complete or partial ablation. Notably, 14 tumors (52%) demonstrated complete ablation, while 8 tumors (30%) showed partial ablation. Patients received a median of 2 treatments of tigilanol tiglate per patient, with a range of 1 to 5 treatments.
"We are delighted with the outcomes from Stage 1 of our Phase IIa Soft Tissue Sarcoma trial," said Stephen Doyle, QBiotics' CEO and Managing Director. "Tigilanol tiglate met both its primary and secondary endpoints and delivered patients an impressive 80% Objective Response Rate in injected tumours."
Durable Responses Without Recurrence
A particularly encouraging finding was the durability of complete responses. None of the 14 completely ablated tumors recurred at the 6-month follow-up period, indicating tigilanol tiglate may provide long-term benefit for patients with this rare cancer.
Dr. Edmund Bartlett, Principal Trial Investigator at Memorial Sloan Kettering Cancer Center, commented: "The clinical activity of tigilanol tiglate, which we observed in multiple types of soft tissue sarcoma, was encouraging. I look forward to expanding our experience with this treatment and determining how to integrate it into the care of patients with soft tissue sarcoma."
Favorable Safety Profile
The small molecule therapeutic was administered via intratumoral injection at a dose of 0.5 mg tigilanol tiglate per cm³ of tumor volume. All 11 patients were included in the safety evaluation, and tigilanol tiglate was well tolerated. Most adverse events were expected and related to the local action of the drug, including local pain, swelling, and necrosis at injection sites.
Addressing Unmet Medical Need
Soft tissue sarcoma represents a significant unmet medical need, with approximately 128,000 new cases reported globally in 2023 and an incidence growing at 0.54% per year. STS is a rare type of cancer that generally forms as a painless lump in any of the soft tissues in the body, making effective treatments particularly valuable for patients.
Potential Synergy with Systemic Therapies
Beyond the direct tumor ablation effects, investigators observed that three patients exhibited better than expected responses to subsequent systemic therapy following tigilanol tiglate treatment. These findings, presented at the Connective Tissue Oncology Society (CTOS) Annual Meeting in November 2024, suggest the drug may enhance responses to standard systemic therapies in metastatic STS.
Advancing to Stage 2 Expansion
Based on these positive results, QBiotics has moved forward with Stage 2 of the trial, which aims to further investigate the clinical utility and therapeutic potential of tigilanol tiglate in patients with STS. The expansion phase is set to open shortly at Memorial Sloan Kettering Cancer Center with a broader patient cohort.
The QB46C-H07 study is a Phase IIa, open-label clinical trial (NCT05755113) designed as a two-stage evaluation of preliminary efficacy and safety of intratumoral tigilanol tiglate in patients with advanced and/or metastatic STS. Secondary endpoints include safety and tolerability assessments and pharmacokinetics, while exploratory endpoints examine local recurrence rates and changes in tumor biomarkers.
Tigilanol tiglate, QBiotics' lead small molecule compound, was granted Orphan Drug Designation by the US FDA for the treatment of STS in February 2024. The drug is currently in Phase II clinical trials for both soft tissue sarcoma and head and neck cancer, with a veterinary formulation already approved for canine mast cell tumors in major global markets.
