Presented Saturday, June 2, 2018 .
Authors:Roberta Sanfilippo, Elena Fumagalli, Paola Collini, Giovanni Fucà, Salvatore Lorenzo Renne, Marta Barisella, Rossella Bertulli, Salvatore Provenzano, Carlo Morosi, Alessandro Gronchi, Angelo Paolo Dei Tos, Paolo Giovanni Casali; Medical Oncology Unit 2, Medical Oncology Department, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Department of Pathology, Fondazione IRCCS... View More
Abstract Disclosures
Background:
Recently, we showed that the FNCLCC grading system can prognosticate the outcome of retroperitoneal LPS. We aimed to explore the impact of pathological stratification using the FNCLCC grading system on the response to Trabectedin (T) of advanced/metastatic WD/DD LPS.
Methods:
We analyzed patients (pts) with advanced WD/DD LPS and treated with T at our Institution for whom formalin-fixed paraffin-embedded (FFPE) tumor samples were available. Histologically, samples were categorized according to the 2013 WHO classification, complemented by Evans’ refinements. The “cellular subvariant” (CS) was diagnosed in the presence of a non-lipogenic area with a mitotic count < 5/10HPF. In cases in which the mitotic count was ≥5/10 HPF, the diagnosis was DDLPS and graded as 2 or 3 according to the FNCLCC grading system. Patients were divided into two subgroups: WDLPS/CS and G2/G3 DDLPS. Response rate (RR) and progression-free survival (PFS) were compared using the Fisher’s exact test and the log-rank test, respectively.
Results:
We included a total of 39 pts with advanced WD/DD LPS treated with T from April 2003 up to present. In 21 pts the sample analyzed was the primitive tumor prior to starting any systemic treatment. In 18 pts we analyzed the sample obtained at the closest date to T initiation. Four patients had a WDLPS, 7 a CS, 21 a G2 DDLPS and 7 a G3 DDLPS. In the subgroup of 11 WDLPS/CS, 5 partial responses, two minor responses and two stable diseases were observed, while in the subgroup of 28 G2/G3 DDLPS we observed one PR and 13 SD. RR was 45% for WDLPS/CS versus 4% for G2/G3 DDLPS (p = 0.0165). Median PFS was 14 months for WDLPS/CS and 3 months for G2/G3 DDLPS (HR 0.28; 95% CI 0.14-0.59; p = 0.0006).
Conclusions:
In this series, sensitivity to T was higher in WDLPS/CS. If what suggested by this limited retrospective case series analysis were confirmed on larger series, WD/CS vs G2/G3 DD histologies could serve as predictive factors for T in advanced WD/DD LPS.