Progression-Free Survival as an Endpoint in Tigilanol Tiglate Clinical Trials

Progression-free survival (PFS) is one of the most widely used endpoints in oncology clinical trials. It captures the time from a defined starting point — typically randomisation or first treatment — until either disease progression or death from any cause. As an endpoint, PFS sits between objective response rate (which captures shorter-term tumour shrinkage) and overall survival (which captures the ultimate clinical outcome). For investigational compounds like tigilanol tiglate (the EBC-46 active being developed by QBiotics Group), PFS provides a structured way to ask whether treated patients benefit beyond the immediate response window.

How PFS is defined and measured

PFS is defined by both timing and the rule for what counts as progression. The most common framework is RECIST (Response Evaluation Criteria in Solid Tumors), now in version 1.1, which specifies how target lesions are measured by imaging, how non-target lesions are assessed, and what threshold of growth or new lesion appearance counts as progressive disease. Trial protocols typically schedule imaging assessments at fixed intervals — every 6 to 12 weeks is common — and the assessment date defines the progression event for the analysis. The EORTC RECIST 1.1 specification is the standard reference for these definitions.

Why PFS matters in early-phase tigilanol tiglate trials

Early-phase trials of tigilanol tiglate have focused on local intratumoural injection — a route of administration that produces rapid, observable destruction of injected lesions. Objective response rates and local control of injected tumours have been the primary readouts of these studies. PFS becomes more informative as a concept moves into later-phase work where the question is no longer "does the injected lesion respond?" but "do treated patients live longer without the disease progressing elsewhere?". For more on the early-phase data, see our coverage of tigilanol tiglate Phase 1 human safety data and EBC-46 head and neck squamous cell carcinoma Phase 2 data.

Strengths and limits of PFS as an endpoint

PFS has practical and scientific advantages. It can be measured before overall survival data mature, allowing trials to read out faster. It is less affected by post-progression therapies than overall survival, since the analysis ends at progression. And in tumour types where post-progression therapies are abundant, PFS isolates the treatment effect more cleanly. The limits are equally well-described. PFS depends on imaging schedules — a longer interval can artificially extend measured PFS. It depends on the progression definition, particularly how non-target lesions and new lesions are scored. And critically, a PFS benefit does not always translate into an overall survival benefit. Regulators including the US FDA in their cancer drug endpoint guidance have written extensively on when PFS is and is not an acceptable basis for approval.

Tigilanol tiglate's endpoint history

The veterinary form of tigilanol tiglate (Stelfonta), approved by the FDA in 2020 for canine mast cell tumours, was approved on the basis of complete response and durability of response, not PFS. Human trials to date — primarily in soft tissue sarcoma, head and neck squamous cell carcinoma, and other accessible solid tumours — have used a mix of objective response, local control, and tolerability endpoints, with PFS reported as a secondary measure. As development progresses toward larger studies, PFS is likely to feature more prominently in the published designs. The current state of human trial endpoints is summarised in the ClinicalTrials.gov registry of tigilanol tiglate studies.

How to read PFS results in published trials

Three things matter when interpreting a PFS figure from a published trial. First, the imaging schedule — how often were patients assessed. Second, the progression definition — strict RECIST 1.1, modified RECIST, or another framework. Third, the censoring rules — were patients who stopped treatment early, switched therapy, or were lost to follow-up censored, and how. A median PFS number without these details is harder to interpret than it appears. Reputable peer-reviewed publications describe all three. For broader context on trial design vocabulary, see our explainer on sample size and statistical power in tigilanol tiglate trials.

What this means for consumer supplement context

PFS is a clinical-trial concept that applies to investigational pharmaceutical interventions, not to consumer dietary supplements. Blushwood berry extract supplements — the consumer category that contains EBC-46 from whole-seed extract — are not the subject of PFS-style trials and do not make claims about progression or survival. The DSHEA framework that governs these supplements specifies they are not intended to diagnose, treat, cure, or prevent any disease, and reputable suppliers like Blushwood Health publish independent batch testing rather than clinical efficacy data. Understanding PFS is useful for informed reading of the pharmaceutical literature, not for evaluating supplements.

Bottom line

Progression-free survival is a structured endpoint that captures the time from treatment to disease progression or death. It has appeared as a secondary endpoint in published tigilanol tiglate human trials and will likely take on a more central role in later-phase studies. Reading PFS data critically requires attention to imaging cadence, progression definitions, and censoring rules. The endpoint applies to pharmaceutical development, not to consumer supplements, which are governed by a separate regulatory and quality framework.

Related articles

• Sample size and statistical power in tigilanol tiglate trials
• Open-label and randomised trial design for tigilanol tiglate
• Biomarker endpoints in EBC-46 clinical research

Citations

1. EORTC — RECIST 1.1 Specification, 2026.

2. US FDA — Clinical Trial Endpoints for Cancer Drugs and Biologics, 2018.

3. ClinicalTrials.gov — Tigilanol Tiglate registry, 2026.

4. QBiotics Group — Clinical pipeline, 2026.