Every day, there seems to be a biotech breakthrough on Australian soil, and while many of the promising results come from small companies with still more work to do, the nature of the results often give hope that cures to certain injuries, diseases and ailments are just around the corner.
Today, QBiotics Group Ltd announced final efficacy and safety results from Stage 1 of its Phase IIa clinical trial of tigilanol tiglate, reporting a strong Objective Response Rate (ORR) of 80% in patients with advanced Soft Tissue Sarcoma (STS).
The trial (QB46C-H07), conducted at Memorial Sloan Kettering Cancer Center in New York, found that 8 out of 10 evaluable patients achieved either complete tumour ablation (100% reduction in volume) or partial ablation (≥30% reduction), suggesting a high rate of clinical activity. Of the 27 tumours injected, 22 (81%) demonstrated complete or partial response, with 14 tumours completely ablated. None of these 14 tumours had recurred at the six-month follow-up, indicating the treatment’s potential for long-term disease control.
Tigilanol tiglate, a small molecule therapeutic administered via intratumoural injection, was well tolerated across the study cohort, with most adverse events (AEs) related to localised drug activity, such as pain, swelling, and necrosis. The results provide the foundation for advancing to Stage 2 of the trial, which will further explore the compound’s therapeutic utility in a broader patient group.
8 out of 10 evaluable patients achieved either complete tumour ablation (100% reduction in volume) or partial ablation (≥30% reduction).
"We are delighted with the outcomes from Stage 1 of our Phase IIa Soft Tissue Sarcoma trial. Tigilanol tiglate met both its primary and secondary endpoints and delivered patients an impressive 80% Objective Response Rate in injected tumours. Importantly, none of the 14 fully ablated (destroyed) tumours had recurred by the 6-month follow-up period, suggesting tigilanol tiglate may provide long-term benefit for patients. Given soft tissue sarcoma is a challenging cancer to treat, achieving this level of clinical activity is highly encouraging,” QBiotics CEO and managing director Stephen Doyle said.
“Our thanks to every trial patient, and also to the trial investigators, Dr Edmund Bartlett and his team at Memorial Sloan Kettering Cancer Center in New York. Given the positive results from Stage 1 of the trial – and compelling investigator reports that tigilanol tiglate may improve responses to systemic therapies in metastatic STS – we have moved ahead with the expansion arm of the study, announced late last year.”
About STS and tigilanol tiglate
Soft Tissue Sarcoma is a rare form of cancer that can arise in any of the body's soft tissues, including muscles, fat, nerves and blood vessels. Approximately 128,000 new cases were reported globally in 2023, with the incidence rate growing modestly at 0.54% per annum.
Tigilanol tiglate is a novel small molecule compound that promotes rapid destruction of solid tumours via local injection. Developed by QBiotics, it has demonstrated therapeutic activity in both veterinary and human oncology settings and continues to progress through clinical trials targeting difficult-to-treat malignancies such as STS.
Trial overview and design
The QB46C-H07 study (NCT05755113) is a two-stage, open-label, Phase IIa clinical trial designed to assess the preliminary efficacy and safety of tigilanol tiglate in advanced or metastatic STS. Stage 1 enrolled 11 patients, all of whom received intratumoural administration of tigilanol tiglate at a dose of 0.5 milligrams per cubic centimetre of tumour volume. Ten of these patients formed the evaluable population for response analysis, having undergone both baseline and post-treatment tumour assessments.
Each patient received up to five doses of tigilanol tiglate to one or more tumours. The primary endpoint was ORR, determined by the proportion of patients achieving complete or partial ablation of injected tumours or tumour segments, with ‘partial ablation’ defined as a reduction of tumour volume by at least 30%. Secondary endpoints included safety and tolerability, while exploratory objectives examined local recurrence rates and changes in tumour biomarkers.
Efficacy outcomes
Tigilanol tiglate achieved an ORR of 80% among evaluable patients based on the best observed response (BOR) at any time during the study. A total of 27 tumours were treated across the cohort, of which 14 (52%) demonstrated complete ablation and 8 (30%) partial ablation, resulting in 81% of tumours responding to treatment. The median number of treatments per patient was two (range: 1–5).
Importantly, none of the 14 completely ablated tumours recurred within the six-month follow-up period, suggesting durable response to treatment. These results build on preclinical and earlier clinical data that have demonstrated tigilanol tiglate’s tumour-destroying potential across a range of solid tumours.
Dr Edmund Bartlett, Principal Trial Investigator at Memorial Sloan Kettering Cancer Center said, “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.”
Safety profile
All 11 patients were included in the safety analysis. Tigilanol tiglate was generally well tolerated, with most adverse events aligned with its mechanism of action.
These included localised effects such as inflammation, pain, and necrosis at the injection site. No unexpected systemic toxicities were reported, supporting the compound’s potential for broader clinical application.
Next steps: Stage 2 expansion
Given the strong response data from Stage 1 and encouraging investigator observations, QBiotics has moved forward with Stage 2 of the trial. This expansion phase will further explore the clinical benefit of tigilanol tiglate and assess its role alongside systemic therapies.
Notably, three patients demonstrated better-than-expected responses to systemic therapy following treatment with tigilanol tiglate, a finding presented at the Connective Tissue Oncology Society (CTOS) Annual Meeting in November 2024.
Stage 2 of the QB46C-H07 study is set to open shortly at Memorial Sloan Kettering Cancer Center, with an expanded patient cohort to assess broader efficacy, safety, and integration into current treatment paradigms for STS.