Abstract 1628MO
Background
In 2002, the EORTC STBSG reported reference values for conducting phase II clinical trials (CTs) for STS with Progression-Free Rate as primary endpoint (Van Glabbeke et al. EJC 2002). These have been widely used since then. We aim to provide an update focusing on LMS.
Methods
CTs involving advanced or metastatic LMS were identified by literature review (published 2003-2018, ≥ 10 LMS patients). Endpoints of interest were 3- and 6-month PFS. When estimates could not be derived from the publication, data requests were sent out. Treatments (trt) were classified as recommended (R-T) or non-recommended (NR-T) according to the ESMO 2018 guideline. A random effects model was employed to pool trial-specific estimates and obtain overall PFS at 3 and 6 months for first line (1L) and pre-treated (2L+) patients separately. The ESMO Magnitude of Clinical Benefit Scale (ESMO-MCBS) was used to guide the choice of trt effect to target in future trials.
Results
From 32 studies identified, we obtained information so far on 6 1L and 14 2L+ trials. Overall, for 1L, PFS at 3 and 6 months were 78% (95%CI 74-82) and 64% (95%CI 59-68), respectively. No difference was observed between R-T and NR-T due to considerable trial heterogeneity. For 2L+ patients, overall 3-month PFS was 50% (95%CI 44-56 – differences not significant between R-T and NR-T due to trial heterogeneity), and 37% (95%CI 29-44%) / 24% (95%CI 18-30) at 6 months for R/NR-T. Data collection continues. The ESMO-MCBS recommends a HR of at least 0.65 for PFS. The table below summarizes what this translates to for the null hypothesis (H0) and alternative hypothesis (H1) of a study assuming an exponential PFS curve. Table: 1628MO
3 months | 6 months | |||
Ref (H0) | Min target (H1) | Ref (H0) | Min target (H1) | |
1L | 78% | 85% | 64% | 75% |
2L+ | 50% | 63% | 30% | 45% |
Conclusions
This work provides updated thresholds for designing new studies for advanced or metastatic LMS. For 1L trt, a 6-month PFS of 64% can be considered as reference for H0. For 2L+ patients, a 3-month PFS > 50% or 6-month PFS > 30% would suggest drug activity.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
EORTC-Soft Tissue and Bone Sarcoma Group (STBSG).
Funding
EORTC-Soft Tissue and Bone Sarcoma Group (STBSG).
Disclosure
L. D’Ambrosio: Advisory/Consultancy, Advisory Board: PSI; Advisory/Consultancy, Editorial Activity: Novartis; Travel/Accommodation/Expenses: PharmaMar; Travel/Accommodation/Expenses: Eli Lilly; Travel/Accommodation/Expenses: Celgene. W.T.A. Van Der Graaf: Research grant/Funding (institution): Novartis; Advisory/Consultancy, Advisory Board fee: Bayer. All other authors have declared no conflicts of interest.
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