Choi Vs. Recist Assessment of Tumor Response in a Retrospective Analysis of Patients (Pts) Receiving Trabectedin (T) for Advanced Soft Tissue Sarcomas (Asts)

Abstract

ABSTRACT Aim: Post-hoc analyses conducted in pts receiving T (Yondelis®) in clinical trials suggested that tumor assessment based on both size and density at portal time of contrast-enhancement sequences (Choi assessment) provides more valuable information than size measurement only (RECIST). We carried out a retrospective analysis in a real-life cohort of pts, treated in 6 French centers to explore the added value of Choi to RECIST assessment. Methods: All baseline and 1st assessment CT-scans have been centrally reviewed by an experienced radiologist. Eligible criteria included ASTS pts (age ≥18) treated between 01/2007-12/2011, with at least 2 T cycles after failure or intolerance to doxorubicin/ifosfamide. Results: The cohort consists of 134 (61 men; 133 eligible) pts treated with T according to the marketing authorization. Pts had median age of 56 years. Most pts had primary sites in limbs/trunk (61, 45%) and uterus (26, 19%) and histologies of leiomyosarcoma (52, 38%), liposarcoma (24, 18%) and synovial sarcoma (21, 15%). Metastases were present in 113 cases (84%), mainly in lung (85, 63%) and liver (25, 18%). Most pts had previously received doxorubicin (133, 99%) and ifosfamide (99, 74%). Median number of T cycles was 5 (2-33) and the main cause of discontinuation was progressive disease (PD) (105, 78%). RECIST assessment was feasible in 128 cases (96%), whereas Choi assessment in 92 (69%), mainly due to inadequate sequences or exclusive lung met. Concordance between both methods was low (Kappa=0.290). We identified five false-PD (PD according to RECIST but stable disease [SD]/partial response [PR] as per Choi). Univariate analysis did not identify predictive factors for false PD. Median OS of pts with false-PD was better than pts with PD according to both RECIST and Choi (14 vs. 8 months; p=0.052). (n) RECIST in column Choi in row PR SD PD PR 3 30 3 SD 1 15 2 PD 0 11 27 Conclusions: Choi assessment was feasible in 69% of cases; this method could identify pts with false-PD that having better outcome, suggesting that T may slow down the tumor course among pts experiencing PD according to RECIST and that response to treatment should also include Choi assessment. Disclosure: A. Cassar: Employee by Pharmamar; D. Nommay: Employee by Pharmamar N. Penel: Research Grant from Pharmamar No Drug Supply. All other authors have declared no conflicts of interest.